Enhanced coke resistance in methanol to olefins reaction via surplus mesoporosity of fibrous silica-wrapped SAPO-34

Enhanced coke resistance in methanol to olefins reaction via surplus mesoporosity of fibrous silica-wrapped SAPO-34 | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Enhanced coke resistance in methanol to olefins reaction via surplus mesoporosity of fibrous silica-wrapped SAPO-34 Muhammad Hafizuddin Mohd Sofi, Muhamed Yusuf Shahul Hamid, Aishah Abdul Jalil, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4631428/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 21 May, 2025 Read the published version in Environmental Chemistry Letters → Version 1 posted 4 You are reading this latest preprint version Abstract Growing concerns regarding the depletion of petroleum reserves and energy demand necessitate the exploration of alternative methods, such as methanol-to-olefin (MTO), to generate light olefins from non-crude oil sources. However, the industrial application of this method is limited due to the rapid deactivation of the catalyst, which is caused by the microporosity of the commercial catalyst. Here, we synthesized the fibrous silica-wrapped silico-alumino-phosphate (FSAPO-34) using a microemulsion technique with a seed-assisted synthesis method and applied it for the first time in the MTO reaction. The physicochemical properties of the fresh and spent catalysts were characterized by X-ray diffractometer, Fourier transform infrared spectroscopy-potassium bromide, N 2 physisorption, field emission scanning electron microscopy, transmission electron microscopy, NH 3 temperature-programmed desorption, thermal gravimetric analysis, O 2 temperature-programmed oxidation, and Raman spectroscopy. The findings indicated that the formation of fibrous silica on the surface of SAPO-34 exhibited a unique spherical morphology with dendrimeric silica fiber, significantly enhancing the mesoporosity from 0.098 to 1.749 cm³/g compared to commercial microporous SAPO-34. FSAPO-34 demonstrates a significant improvement in catalytic lifetime, with a 54% increase, from 19.2 hours to 29.5 hours, compared to commercial SAPO-34. This enhanced stability is attributed to the introduction of mesoporosity in FSAPO-34, which, in turn, provides high accessibility and reduced diffusion resistance of products and ultimately retarded the formation of coke. Methanol-to-olefins Fibrous Silica Zeolite catalyst SAPO-34 Olefin production Porous materials Figures Figure 1 Figure 2 Figure 3 Figure 4 1. Introduction Light olefins, specifically ethylene and propylene, play a crucial role in the chemical industry as they are widely utilized commodities with diverse applications (Mohammadrezaei et al. 2012 ; Hsu and Robinson 2019 ; Zapater et al. 2021 ). Conventionally, light olefins are primarily generated through the thermal cracking of crude oil and naphtha as a feedstock (Chen et al., 2023 ). This thermal cracking process typically involves high operating temperatures, necessitating a substantial amount of energy, leading to significant emissions of CO 2 and CO (Ren et al. 2006 ; Sadrameli 2016 ; Lal et al. 2021 ). In addition, the depleting availability of reserves and the increasing costs of crude oil reduce the viability of this process (Liu et al. 2017 ; Sun et al. 2020 ; Lal et al. 2021 ). The significant increase in global energy demand, along with environmental concerns, has propelled researchers to explore alternative methods for light olefin production as a replacement for the current fossil fuel-based process (Hafeez et al. 2020 ; Deka et al. 2022 ). In response to the shift towards a more sustainable future, the methanol-to‐olefin (MTO) reaction has proven to be a successful non‐petroleum pathway to generate light olefins and become important to worldwide catalytic technologies that rely on abundant resources such as CO 2, coal, natural gas, and biomass with methanol serving as the intermediate compound (Lais et al. 2018 ; Sun et al. 2018 ; Valecillos et al. 2020 ; Minova et al. 2021 ). Zeolite has been widely used as the most important solid heterogeneous catalysts in several industrial processes, including methanol conversion to light olefins, due to their excellent shape selectivity and exceptional characteristics of their active sites (Guisnet et al. 2009 ; Zhang et al. 2016 ; García-Ruiz et al. 2020 ). Among the different types of zeolites, silico-alumino-phosphate (SAPO) zeolite SAPO-34 is considered as the epitome catalyst for MTO reaction due to its capability to yield high selectivity of ethylene and propylene (Bakhtiar et al. 2018 ). This is attributed to the inherent characteristics of SAPO-34, which features an appropriate acidity with CHA (Chabazite) supercages consisting of small 8-membered ring pore aperture (3.8 Å × 3.8 Å) (Liu et al. 2008 , 2017 ). However, despite the impressive catalytic performance exhibited by SAPO-34 in MTO reactions, it comes with a significant drawback, which is rapid deactivation. The narrow pore aperture of SAPO-34 hinders the mass transport and diffusion of bulky molecules as intermediate products. This obstruction leads to the blockage of the microporous channels of the catalyst and coverage of the acidic active sites due to coke deposition, resulting in the deactivation of the catalyst (Jin et al. 2018 ; Soltanali and Darian 2019 ). Consequently, SAPO-34 catalysts have short catalytic lifetimes and require continuous regeneration (Zhou et al. 2018 ; Zapater et al. 2021 ). Hence, the challenge lies in effectively controlling and mitigating coking formation while simultaneously preserving or improving its catalytic performance in developing SAPO-34 catalysts. In the past few years, various strategies have been taken into action to overcome the inherent diffusion limitation to reduce the coke deposition and consequently increase catalyst lifetime, such as reducing the crystal size and creating a hierarchical structure. For instance, Wang et al. prepared a range of SAPO-34 catalysts with different crystal sizes (160–1100 nm) by a two-step hydrothermal crystallization which shows that SAPO-34 with smaller crystal sizes exhibits superior catalytic activity and stability (Wang et al. 2013 ). Commonly, hierarchical pore structures are achieved by either pre-synthesis using multiple structure directing agents or post-synthesis treatment using different types of acid (Sun et al. 2014 ; Ren et al. 2017 ; Han et al. 2021b ; Zheng et al. 2022 ). Both approaches successfully introduce mesopores and macropores into microporous SAPO-34, which led to excellent MTO catalytic performance with a suppressed coke deposition and a longer catalytic lifetime. Although there has been a notable development in modifying pure microporous zeolite using the aforementioned method, the creation of secondary porosities always contributes to the destruction of some micropore structures, resulting in structural defects (Wang et al. 2023 ). In recent times, introducing a hierarchical structure in microporous zeolites through the formation of a core and shell catalyst has gained significant interest among researchers in this field. For example, Chen et al. report a novel method to synthesize ZSM-5 as a core with SAPO-34 layer on the surface by introducing ZSM-5 into the synthesis gel of SAPO-34 under hydrothermal conditions (Chen et al. 2020 ). Wang et al. took a different approach by coating the SAPO-34 core with an MCM-41 shell, which was then transformed into a ZSM-5 shell through in situ solid-solid transformation (Wang et al. 2023 ). The combined benefits of a hierarchical pore system and distinct zeolite phases have resulted in the core-shell composite catalyst exhibiting exceptional catalytic performance and lifetime. Besides the selective shell, an inert shell such as KAUST Catalysis Center-1 (KCC-1, also known as fibrous silica) has been utilized to construct core-shell zeolite. Polshettiwar et al. were the first to introduce this novel morphology with distinct properties which is considered a promising alternative for creating a new zeolite structure (Polshettiwar et al. 2010 ). This fact was supported by excellent performances of fibrous silica mesoporous zeolite due to high surface area and mesopore volume, resulting in high accessibility and low diffusion limitations, as shown in various catalytic reactions such as cumene hydrocracking (Firmansyah et al. 2016 ), toluene methylation (Ghani et al. 2019 ), cyclic and noncyclic alkane isomerization (Izan et al. 2020 ), and CO 2 methanation (Hussain et al. 2020c ). Inspired by this discovery, we synthesized fibrous silica-wrapped SAPO-34 (FSAPO-34) for the first time and investigated its physicochemical properties along with its catalytic performance in the MTO reaction. 2. Experimental 2.1 Chemicals and Materials The commercial SAPO-34 was purchased from ZR Catalyst Co., Ltd, while cetyltrimethylammonium bromide (CTAB, (C 16 H 33 )N(CH 3 ) 3 Br, > 98%), urea (CH 4 N 2 O, > 99.5%), toluene (C 7 H 8 , 98%), 1-butanol (C 4 H 10 O, 98%), tetraethyl orthosilicate (TEOS, Si(OC 2 H 5 ) 4 , > 98%) and methanol (CH 3 OH, 99.5%) were purchased from Merck. The hydrogen (H 2 , 99.5%), nitrogen (N 2 , 99.5%), and compressed air (> 90%) cylindrical gas tanks were purchased from Mega Mount Industrial Gases. All compounds and chemicals were utilized as purchased without undergoing any additional purifying processes. 2.2 Catalyst preparation Fibrous silica-wrapped SAPO-34 was synthesized using the microemulsion method in combination with the zeolite seed-assisted method using commercial SAPO-34. The fibrous silica-wrapped SAPO-34 was prepared with initial molar ratio parameters of urea : CTAB : toluene : 1-butanol : H 2 O : seed : TEOS = 0.98 : 0.27 : 27.58 : 1.6 : 152.52 : 0.38. Initially, the CTAB that acts as a structure-directing agent and urea were dissolved in distilled water, followed by adding toluene and 1-butanol while maintaining stirrer condition at room temperature. After obtaining a homogeneous solution, the commercial SAPO-34 seed was introduced to the mixture before being stirred vigorously for another hour while maintaining the same temperature. Then, TEOS was dropwise introduced to the mixture and stirred for four hours. Subsequently, the obtained mixture was exposed to intermittent microwave radiation (400 W) for eight hours. The solid product was collected through centrifugation at a speed of 4000 rpm and thoroughly rinsed with distilled water several times. Finally, the resulting product was dried at 120°C overnight and calcined at 550°C for six hours to eliminate the structure-directing agent. 2.3 Catalyst characterization 2.3.1 Characterization of fresh catalyst The fresh catalysts under study were analyzed using various characterization methods. The analysis of catalyst crystalline structure was carried out using an X-ray diffractometer (XRD) (Bruker Advanced D8 X-ray) equipped with Cu Kα radiation (λ = 1.5406 Å), 2θ scan range of 5°-40°, scanning rate of 45 kV and step size of 40 mA. To identify the functional groups on the catalysts, the Fourier transform infrared spectroscopy with potassium bromide (FTIR-KBr) method was employed using an Agilent Cary 640 spectrometer, with 5 sample scans conducted at a resolution of 5 cm − 1 . N 2 physisorption studies on the catalysts were performed using a Beckman Coulter SA 3100 instrument. The surface area and pore volume were computed using the Brunauer–Emmett–Teller (BET) method, while the pore size distribution was determined using non-local density functional theory (NLDFT). In addition, the acidity of the catalysts was examined through the ammonia temperature-programmed desorption (NH 3 -TPD) technique utilizing Micromeritics Chemisorb 2720 Pulse Chemisorption equipment. The chemical compositions of samples were analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES) (PerkinElmer, Inc., Shelton, CT, USA). The morphological properties of the catalyst were analyzed using field emission scanning electron microscopy (FESEM) (JEOL JSM- 6701F, Japan) and transmission electron microscopy (TEM) (Philips EM420, USA). 2.3.2 Characterization of spent catalyst. The spent catalysts undergo several characterization techniques. The amount of carbon deposited on the spent catalyst was assessed using thermal gravimetric analysis (TGA) conducted with a Mettler Toledo (SDTA-851) instrument in the air stream. The nature of carbon deposits on the spent catalyst was examined using the Renishaw Raman spectroscopy instrument. To characterize the carbon deposited on the spent catalyst, the oxygen temperature-programmed oxidation (O 2 -TPO) of catalysts was performed using the Micromeritics Chemisorb 2720 equipment. Transmission electron microscopy was utilized to study the morphology of the spent catalyst using the same equipment as fresh catalyst characterization. 2.4 Catalytic testing The catalytic performance was performed using a micro-catalytic reactor. Prior to catalytic testing, 0.25 g of sieved catalyst was placed in an 8 mm quartz tube. The catalyst was treated by exposed to a compressed air stream (120 mL/min) at 450°C for 60 minutes. For catalytic performance, 0.03 ml methanol was injected into the treated catalyst with N 2 as the carrier gas at a 70 mL/min flow rate. Meanwhile, methanol was continuously introduced to the catalyst for evaluating catalytic lifetime using an automatic syringe pump at a weight hourly space velocity of 6.9 h − 1 , maintaining the same N 2 flow rate. The resulting products were examined using an Agilent Gas Chromatography 7820A FID fitted with an HP-5 capillary column. The catalytic performance was evaluated at different temperature ranges of 300 to 500°C, and the stability of the catalyst was assessed at a constant temperature of 500°C over time on stream of 30 hours. The methanol conversion, selectivity, and yield were calculated by equations (1), (2), and (3), respectively (Hadi et al. 2018 ). $$Methanol conversion \left(\%\right)= \frac{{N}_{MeOH in}- {N}_{MeOH out}}{{N}_{MeOH in}}\times 100 \left(1\right)$$ $$Hydrocarbon selectivity \left(\%\right)= \frac{{N}_{Ci}}{{N}_{MeOH in}- {N}_{MeOH out}}\times 100 \left(2\right)$$ $$Yield \left(\%\right)= \frac{methanol conversion \times hydrocarbon selectivity}{100} \left(3\right)$$ where N is the number of moles. The subscripts MeOH in and MeOH out represent the methanol inlet and outlet of the reactor, respectively. The term N MeOH in – N MeOH out refers to the reacted moles of methanol. Subscript Ci indicates the individual hydrocarbon produced in the MTO reaction. 3. Results and discussion 3.1. Characterization of fresh catalysts 3.1.1. Crystallinity, functional group, and textural analysis Figure 1 a shows the wide-angle X-ray diffractograms of both the commercial SAPO-34 and the synthesized FSAPO-34 catalysts. Several distinct peaks are detected at 2θ = 9.6°, 13°, 16.3°, 17.9°, 20.9°, 25.1°, and 31°, which correspond to the (101), (110), (021), (003), (12–1), (220) and (401) crystallographic planes, respectively, that ascribed to a typical diffraction peak of SAPO-34 (CHA-type zeolite). Both samples exhibit a rhombohedral SAPO-34 structure with the most substantial XRD diffraction peak at 2θ = 9.6 (JCPDS file No. 01-087-1527) (Soheili et al. 2021 ). However, the intensity of the XRD pattern of FSAPO-34 was reduced compared to that of commercial SAPO-34, which indicates a substantial loss of crystallinity during the modification process. This could be due to the growth of silica species during the formation of dendrimeric silica fiber. This phenomenon was consistent with previous studies for other fibrous silica zeolite such as fibrous silica Beta (Hussain et al. 2020a ), fibrous silica ZSM-5 (Teh et al. 2016 ), and fibrous silica MOR (Hussain et al. 2020c ). Besides, a broad diffraction peak centered 2θ = 23° is observed for FSAPO-34 due to the amorphous feature of the silica shell (Qureshi and Jaseer 2020 ). This broad peak was not detected in other fibrous silica zeolite material, possibly due to the different mechanisms for the formation of dendrimeric silica fiber on the SAPO-34 surface, as depicted in Fig. S1 . The FTIR method is frequently utillized to determine the stretching and bending vibrations of various types of bonds present in the structure of catalysts. Figure 1 b illustrates the FTIR-KBr spectrum of commercial SAPO-34 and FSAPO-34 in a 400–1400 cm − 1 frequency range. Clearly, all the examined catalysts exhibited five almost identical IR bands spanning from 400 to 1400 cm − 1 . The absorption peaks observed at wavenumbers of 1092 cm − 1 , 972 cm − 1 , 802 cm − 1 , and 467 cm − 1 correspond to the vibration of asymmetric Si-O-Si stretching, external Si-OH, symmetric Si-O-Si stretching, and Si-O-Si bending vibration, respectively (Azami et al. 2021 ; Bahari et al. 2022 ). While the band at 635 cm − 1 is a result of the structurally sensitive double 6-membered ring vibrations, which are distinctive features of the CHA framework (Liu et al. 2008 ; Soltanali and Darian 2019 ). The synthesized FSAPO-34 shows a higher intensity, which is dominated by a strong band at 1092 cm − 1 , 802 cm − 1 , and 467 cm − 1 , confirming the presence of silica fibers surrounding the SAPO-34 seed, consistent with XRD results. An additional peak was noticed at 960 cm –1 only for the FSAPO-34, which was ascribed to bending vibrations of Si-OH. This occurrence could be attributed to the increased abundance of terminal silanol groups formed during the synthesis of silica fibers. The textural characteristics of the catalysts were investigated via N 2 physisorption isotherms, with pore size distributions determined using non-local density functional theory (NLDFT) for clearer analysis. The commercial SAPO-34 exhibited a distinct type I isotherm, affirming the catalyst's microporous structure in accordance with IUPAC classification and aligning with findings in the literature (Chen et al. 2016 ; De Araujo et al. 2022 ). Conversely, FSAPO-34 catalysts displayed a type IV isotherm with an H3 hysteresis loop, which verifies a distinctive adsorption profile for mesoporous catalysts with slit-shaped pores (Fig. 1 c) (Numpilai et al. 2021 ). Both catalysts demonstrate nearly identical N 2 adsorption at lower relative pressure, indicating the presence of microporosity in the catalysts. However, FSAPO-34 shows a greater N 2 adsorption at higher relative pressures, suggesting the existence of mesopores (Hussain et al. 2020b ). In addition, the N 2 uptake at relative pressures of 0.3 and 0.9 are assigned to intra- and interparticle pores, respectively (Hamid et al. 2017 ). A notable increase in N 2 uptake at a relative pressure of 0.9 was observed for FSAPO-34 compared to SAPO-34. This finding indicates that the fibrous silica form on the surface of SAPO-34 significantly contributed to the abundance of interparticle pores. The hysteresis loops observed in the case of FSAPO-34 substantiate the effective formation of mesopores. This observation aligns with the pore distributions derived from the NLDFT method illustrated in Fig. 1 d, which shows that a peak within the less than 2 nm range signifies the existence of micropores, whereas a peak within the greater than 2 nm range indicates the presence of mesopores. Although FSAPO-34 displayed a similar pore size distribution to SAPO-34 at a lower range (< 2 nm), the emergence of a broader peak in the 3–6 nm range indicates the formation of larger mesopores which is undoubtedly due to fibrous dendrimeric morphology. This improvement in mesoporous characteristics could potentially improve the mass transfer properties and negate the diffusion limitations associated with the commercial SAPO-34 catalyst. Detailed information regarding the physical characteristics of SAPO-34 and FSAPO-34 are tabulated in Table S1 . 3.1.2. Morphological studies Figure 2 reveals the FESEM and TEM images of SAPO-34 and FSAPO-34. From Fig. 2 a, it can be seen that the unmodified SAPO-34 presents the common cubic morphology, characterized by a smooth and compact surface, which is identical to the conventional SAPO-34 (Bakhtiar et al. 2018 ). After undergoing synthesis using the microemulsion method, the FESEM image of FSAPO-34 reveals the development of spherical silica with well-ordered dendrimeric morphology, characterized by a uniform size of 150–200 nm (Fig. 2 b-d ) . This distinctive spherical morphology covers the surface of the cubic particles of SAPO-34, as shown in Fig. 2 c. Notably, a TEM image of FSAPO-34 (Fig. 2 e-f) shows an accumulation growth of fibrous silica on one side of the cubic SAPO-34 surface. Clearly, the EDX mapping of FSAPO-34 shows a high intensity of silica surrounding the outer surface of the core SAPO-34 (Fig. 2 h ) , indicating a good dispersion of fibrous silica. This result may claim the formation of a core and shell structure of FSAPO-34. In addition, a TEM image of a single fibrous silica (Fig. 2 g) further confirms the particle's spherical form, enriched with dendrimeric fibers on its external surface. These spherical morphological characteristics closely resemble those of KAUST Catalysis Center-1, as described by Polshettiwar (Polshettiwar et al. 2010 ). It should be noted that this result differs from other fibrous zeolite materials, where the center of the sphere consists of an aluminosilicate framework of zeolite, while the dendrimer was fully composed of silica (Teh et al. 2016 ; Abdul Jalil et al. 2019 ). This observation further clarifies the distinctive broad diffraction peak revealed in XRD results (Fig. 1 a) exclusively in the case of FSAPO-34. 3.2. Catalytic performance and lifetime of catalysts The MTO reaction was carried out in a micro-catalytic reactor over the commercial SAPO-34 and synthesized FSAPO-34. The conversion of methanol, selectivity of products, and light olefins yield were displayed in Fig. 3 (a-c) and computed in Table S2 . At lower temperatures (300–350°C), the parent catalyst shows a better conversion compared to FSAPO34. However, the conversion at higher temperatures (> 400°C) shows little disparity between both catalysts, which achieved above 95% methanol conversion. The reduced methanol conversion of FSAPO-34 can be associated with the decrease in weak acid sites, as shown in Fig. S2 ( a-b ), since these sites are involved in facilitating the conversion of methanol to DME as well as alkylation and methylation reactions prior to the formation of olefin products (Wu et al. 2011 ; Yang et al. 2012 ). It is worth mentioning that as the reaction temperature increases for both catalysts, the selectivity towards light olefins increases, where ethylene is the major product compared to propylene, accompanied by the gradual decrease of the concentration of other hydrocarbons appear among the effluents, which is similar to a pattern observed in previous work involving SAPO-34 (Castellanos-Beltran et al. 2018 ). The high light olefin yield was obtained over SAPO-34 at 500°C, which is 90.1% with a total light olefin selectivity of 93.1%, while for FSAPO-34, there was a slight 1.4% and 1.1% reduction in light olefin yield and selectivity, respectively, at the same temperature. At the lower reaction temperature (300°C), commercial SAPO-34 demonstrates the capability to produce a higher amount of ethylene and propylene (49.2%) compared to FSAPO-34 (15.2%). At this temperature, FSAPO-34 tends to produce more DME compared to SAPO-34, which highlights the deficiency of strong acid sites, as the olefin formation is only feasible on strong acid sites (Ghavipour et al. 2023 ). It is well known that the appropriate strength and amount of strong-acid sites on the surface of SAPO-34 is crucial to achieving high selectivity of light olefin, as demonstrated in the previous report (Wang et al. 2013 ; Hasnain Bakhtiar et al. 2024 ). The inactivity of silica fiber employed in FSAPO-34 resulted in the dilution of a strong acid site in SAPO-34 and thus led to a lower selectivity of ethylene and propylene. The catalytic lifetime of the SAPO-34 and FSAPO-34 catalysts for continuous MTO reaction was examined, and the conversion of methanol was plotted as a function of the time on stream, as illustrated in Fig. 3d . The catalyst lifetime was defined as the duration of continuous reaction maintaining the catalyst activity until the methanol conversion lower than 50% (Wu and Hensen 2014 ). During the catalytic stability test, FSAPO-34 demonstrated an extended catalytic lifetime of 29.5 hours, sustaining a methanol conversion above 50% in contrast to commercial SAPO-34, which has a shorter catalytic lifetime of 19.2 hours. Although the strong acid sites of commercial SAPO-34 led to better light olefin selectivity, it also can expedite the formation of carbon-carbon bonds, leading to the generation of aromatics, which are side reactions that can cause a buildup of carbon deposits within the zeolite's pore structure (Zhang et al. 2018 , 2019 ). On the other hand, the microporous nature of commercial SAPO-34, as shown in N 2 physisorption results (Fig. 1 c), often introduces diffusion limitations for the aromatics and branched hydrocarbons formed within the pores (Wang et al. 2013 ; Han et al. 2021a ). All of these factors ultimately led to the rapid deactivation of commercial SAPO-34. Thus, introducing mesopores into the synthesized FSAPO-34 structure can enhance the diffusion of products out of the pores, effectively reducing diffusion resistance, which impedes blockage of the pores caused by coke deposition (Sun et al. 2015 ). Hence, the extended stability duration observed in FSAPO-34 signifies a remarkable resistance to deactivation. 3.3. Analysis of spent catalysts Catalytic processes using zeolite-type catalysts frequently involve side reactions resulting in the development of carbonaceous material known as coke, which is the primary factor responsible for the deactivation of catalyst in the MTO reaction (Guisnet et al. 2009 ). The TGA and DTG analysis was used to measure the amount of coke deposits over spent SAPO-34 and FSAPO-34 catalysts at the temperature range of 30 to 900°C, and the results are shown in Fig. 4 (a-b). The initial weight loss at temperatures below 200°C is attributed to the removal of water and decomposition of volatile materials from the catalyst (Dai et al. 2013 ; Varzaneh et al. 2014 ). The second weight loss occurring between 200 to 800°C primarily results from the combustion of coke deposits on the catalyst (Varzaneh et al. 2016 ; Aghamohammadi and Haghighi 2019 ). These carbonaceous deposits can be categorized into three distinct types based on temperature ranges: 200–400°C, 400–600°C, and above 600°C. The initial range is identified as the soft coke category, characterized by a higher H/C ratio with higher combustion reactivity and a lower activation energy value. The second weight loss classifies as hard coke region with a lower H/C ratio relative to soft coke. The third category of weight loss, which occurs at temperatures exceeding 600°C, is referred to as laid coke. Laid coke is particularly hard to decompose in the de-coking process (Ahmed et al. 2011 ; Aghamohammadi and Haghighi 2019 ; Díaz et al. 2021 ). It can be seen that both SAPO-34 and FSAPO-34 showed a decrease in weight as the temperature increased ( Fig. 4 a ) . However, the synthesized FSAPO-34 showed a weight loss of 24%, significantly lower than the 35% weight loss observed for SAPO-34, which indicates that less amount of carbon deposits formed on FSAPO-34 during MTO catalytic reaction. In addition, according to DTG curves presented in Fig. 4 b, the spent FSAPO-34 mostly shows a formation of hard coke within the temperature range of 400 to 600°C while SAPO-34 shows an additional peak at temperatures above 600°C implying the generation of laid coke. The O 2 -TPO analysis was carried out to further confirm the amount and characteristics of carbon deposition of spent SAPO-34 and FSAPO-34. Figure 4 c shows the O 2 -TPO profiles over the 100– 850°C oxidation temperature range. Similar to TGA analysis, the coke species were classified by different oxidation temperatures into three types, including C A decomposed at low temperature (350–450°C), C B decomposed at moderate temperature (450–600°C), and C C decomposed at high temperature (600–750°C) (Fakeeha et al. 2013 ; Díaz et al. 2021 ). These sections correspond to amorphous, filaments, and graphite carbon, respectively (Hussain et al. 2020c ). As expected, comparing the area of the coke-burning peak of both samples, it is evident that the area of the coke-burning peak of the SAPO-34 is substantially greater than that of the FSAPO-34 with 10.2 mmol/g Cat and 2.6 mmol/g Cat consumption of O 2 , respectively. Furthermore, the maximum temperature of the coke-burning over the SAPO-34 shifted to the C C region which resulted in a more substantial peak area in the C C region compared to the FSAPO-34. The C C species is characterized by its thermal stability, making it challenging to decompose at high temperatures. Consequently, there is a possibility that this species could obstruct active sites and pores of the catalyst, leading to a reduction in the surface reaction during the MTO process (Yaripour et al. 2015 ; Liu et al. 2017 ). These observations are in agreement with the N 2 physisorption ( Fig. S3 ), which shows a smaller reduction in surface area and pore volume for FSAPO-34 compared to SAPO-34 after 30 hours of continuous catalytic reaction, which indicates less carbon deposition within the surface and pores of the spent FSAPO-34. To differentiate the various carbon species present in SAPO-34 and FSAPO-34 catalysts after 30 hours of reaction, Raman spectroscopy was utilized, and the corresponding results are illustrated in Fig. 4 d. The existence of two separate bands at 1350 cm − 1 can be ascribed to the disorder-induced band (D-band) resulting from carbon atoms bonded through sp2 hybridization and the graphite carbon band (G-band) resulting from by C-C stretching at 1590 cm − 1 , respectively. In this context, the coexistence of D and G bands indicates that both SAPO-34 and FSAPO-34 exhibited the presence of amorphous and graphite carbon during the MTO reaction. However, compared with the SAPO-34, the G band and D band spectra of the FSAPO-34 exhibit lower intensities, and this intensity of the bands reflects the quantity of carbon deposited during the reaction (Hussain et al. 2019 ; Owgi et al. 2023 ; Hatta et al. 2023 ). Furthermore, the degree of carbon deposit graphitization is often measured by the ratio of these two bands, known as I G /I D . A higher I G /I D ratio indicates a higher rate of graphitic carbon formation, which is a stable form of carbon deposits compared to very unstable and amorphous carbon. This led to the rapid deactivation of the catalyst and a tougher regeneration process (Rahman et al. 2022 ). The calculated value of the I G /I D ratio for FSAPO-34 and SAPO-34 was found to be 0.68 and 0.82, respectively, which confirmed that the synthesized FSAPO-34 contained less graphitic carbon than SAPO-34 owing to its distinctive fibrous structure. These observations were in accordance with the fact that FSAPO-34 displayed better stability relative to SAPO-34 during the stability test ( Fig. 3d ). TEM analysis was carried out to examine the morphological characteristics of spent FSAPO-34, as depicted in Fig. 4 ( e-f ). As depicted in Fig. 4 e, a portion of the fibrous silica shell has been relocated from the core SAPO-34 after 30 hours of MTO reaction. This relocation could be attributed to the aggregation of fibrous silica since it is not fully intact with the core SAPO-34, as observed in the TEM image of the fresh FSAPO-34 sample (Fig. 2 e-f). However, it is clear that the fibrous silica structure underwent no morphological change and retained its fibrous nature after the stability test, proving the strong integrity of the fibrous silica structure (Fig. 4 f). In addition, the filamentous carbon species (whisker carbon) with similar morphology from the literature (Helveg et al. 2011 ; Simakov et al. 2015 ) were visible and extensively formed on the spent FSAPO-34, as evidenced by the TGA, O 2 -TPO, and Raman data. This type of carbon is expected to be produced from the MTO reaction since the light olefins produced from the reaction could further react to form higher olefins, paraffins, aromatics, and naphthenes through hydrogen transfer reaction or aromatization (Stö 1999 ; Olsbye et al. 2012 ). These hydrocarbons finally condense to form carbon deposition, which is usually seen as filamentous carbon deposition (Dong et al. 2022 ). On the basis of the above results, it is concluded that the synthesized FSAPO-34 displays a high resistance toward coke deposition, which leads to high catalytic stability in the MTO reaction due to the formation of fibrous silica on SAPO-34. Conclusion and Future Prospects In conclusion, fibrous silica-wrapped SAPO-34 (FSAPO-34) with well-ordered dendrimeric morphology was successfully synthesized through microemulsion coupled with a seed-assisted synthesis method. Unlike other fibrous silica zeolite materials, fibrous silica tends to disperse on the surface of SAPO-34, as shown in morphological studies and proposed formation mechanism due to the micro-sized seed of the SAPO-34 and the inherent resistance SAPO-34 structure toward basic media. Nevertheless, the prepared FSAPO-34 introduces a unique structural feature that comes with high surface area, mesopores volume, and reduced weak and strong acidity. Commercial SAPO-34 has superior catalytic performance in terms of methanol conversion and light olefins selectivity compared to FSAPO-34 at lower temperatures temperature due to reduced weak acid sites and deficiency strong acid sites in FSAPO-34, respectively. Nevertheless, when exposed to high temperatures, the FSAPO-34 can preserve its catalytic activity, showing little disparities in conversion and light olefin selectivity compared to SAPO-34, with differences of 0.3% and 1.1%, respectively. The high mesopore volume of FSAPO-34 contributes to its remarkable catalytic stability due to high accessibility and low diffusion limitations of hydrocarbon products, resulting in a 54% improvement (from 19.2 hours to 29.5 hours) compared to commercial SAPO-34. Based on the thermal gravimetric analysis, O 2 temperature-programmed oxidation, Raman, and transmission electron microscopy results of spent catalysts, FSAPO-34 exhibits more resistance towards coke formation compared to commercial SAPO-34. Overall, these findings position FSAPO-34 as a promising catalyst for the MTO process and provide new insight into the designing and fabricating highly efficient catalysts for light olefin production. Declarations Acknowledgments As authors, we are gratefully acknowledging the Universiti Teknologi Malaysia for the Fundamental Research Grant (No. 5F575). References Abdul Jalil A, Zolkifli AS, Triwahyono S, et al (2019) Altering Dendrimer Structure of Fibrous-Silica-HZSM5 for Enhanced Product Selectivity of Benzene Methylation. Ind Eng Chem Res 58:553–562. https://doi.org/10.1021/acs.iecr.8b03147 Aghamohammadi S, Haghighi M (2019) Spray-dried zeotype/clay nanocatalyst for methanol to light olefins in fluidized bed reactor: Comparison of active and non-active filler. Appl Clay Sci 170:70–85. https://doi.org/10.1016/j.clay.2019.01.006 Ahmed R, Sinnathambi CM, Subbarao D (2011) Kinetics of De-coking of Spent Reforming Catalyst. Journal of Applied Sciences 11:1225–1230. https://doi.org/10.3923/jas.2011.1225.1230 Azami MS, Jalil AA, Hassan NS, et al (2021) Green carbonaceous material‒fibrous silica-titania composite photocatalysts for enhanced degradation of toxic 2-chlorophenol. J Hazard Mater 414:. https://doi.org/10.1016/j.jhazmat.2021.125524 Bahari MB, Mamat CR, Jalil AA, et al (2022) Enriching the methanol generation via CO2 photoconversion over the cockscomb-like fibrous silica copper. Fuel 328:. https://doi.org/10.1016/j.fuel.2022.125257 Bakhtiar SUH, Wang X, Ali S, et al (2018) CTAB-assisted size controlled synthesis of SAPO-34 and its contribution toward MTO performance. Dalton Transactions 47:9861–9870. https://doi.org/10.1039/C8DT01811A Castellanos-Beltran IJ, Assima GP, Lavoie JM (2018) Effect of temperature in the conversion of methanol to olefins (MTO) using an extruded SAPO-34 catalyst. Front Chem Sci Eng 12:226–238. https://doi.org/10.1007/s11705-018-1709-8 Chen J, Cai R, Huang H, et al (2023) Collaborative removal of fine catalysts particles and insoluble organics from methanol-to-olefins reaction wastewater using horizontal swirl regeneration micro-channel separation (HSRMS). Process Safety and Environmental Protection 177:340–354. https://doi.org/10.1016/j.psep.2023.05.059 Chen X, Jiang R, Hou H, et al (2020) Synthesis of ZSM-5/SAPO-34 zeolite composites from LAPONITE® and their catalytic properties in the MTO reaction. CrystEngComm 22:6182–6188. https://doi.org/10.1039/d0ce01002b Chen X, Vicente A, Qin Z, et al (2016) The preparation of hierarchical SAPO-34 crystals via post-synthesis fluoride etching. Chemical Communications 52:3512–3515. https://doi.org/10.1039/c5cc09498d Dai W, Wu G, Li L, et al (2013) Mechanisms of the deactivation of SAPO-34 materials with different crystal sizes applied as MTO catalysts. ACS Catal 3:588–596. https://doi.org/10.1021/cs400007v De Araujo BRS, Onrubia-Calvo JA, Stambouli I, et al (2022) Towards the development of advanced hierarchical chabazite materials: Novel micro-mesoporous silicoaluminophosphate SAPO-34 zeolites. Mater Today Commun 31:. https://doi.org/10.1016/j.mtcomm.2022.103580 Deka TJ, Osman AI, Baruah DC, Rooney DW (2022) Methanol fuel production, utilization, and techno-economy: a review. Environ Chem Lett 20:3525–3554 Díaz M, Epelde E, Valecillos J, et al (2021) Coke deactivation and regeneration of HZSM-5 zeolite catalysts in the oligomerization of 1-butene. Appl Catal B 291:. https://doi.org/10.1016/j.apcatb.2021.120076 Dong P, Shao T, Zhao Y, et al (2022) Progress of Methylation of C6-8~Arene with Methanol: Mechanism, Catalysts, Kinetic/Thermodynamics and Perspectives. Processes 10:. https://doi.org/10.3390/pr10050881 Fakeeha AH, Khan WU, Al-Fatesh AS, Abasaeed AE (2013) Stabilities of zeolite-supported Ni catalysts for dry reforming of methane. Cuihua Xuebao/Chinese Journal of Catalysis 34:764–768. https://doi.org/10.1016/s1872-2067(12)60554-3 Firmansyah ML, Jalil AA, Triwahyono S, et al (2016) Synthesis and characterization of fibrous silica ZSM-5 for cumene hydrocracking. Catal Sci Technol 6:5178–5182. https://doi.org/10.1039/c6cy00106h García-Ruiz M, Solís-Casados DA, Aguilar-Pliego J, et al (2020) Synthesis of 10 and 12 Ring Zeolites (MCM-22, TNU-9 and MCM-68) Modified with Zn and Its Potential Application in the Reaction of Methanol to Light Aromatics and Olefins. Top Catal 63:451–467. https://doi.org/10.1007/s11244-020-01242-x Ghani NNM, Jalil AA, Triwahyono S, et al (2019) Tailored mesoporosity and acidity of shape-selective fibrous silica beta zeolite for enhanced toluene co-reaction with methanol. Chem Eng Sci 193:217–229. https://doi.org/10.1016/j.ces.2018.09.009 Ghavipour M, Goncalves TJ, Al Hussami R, et al (2023) Uncovering the role of Lewis and Brønsted acid sites in perforated SAPO-34 with an enhanced lifetime in methanol conversion to light olefins. New Journal of Chemistry 47:15907–15921. https://doi.org/10.1039/d3nj02514d Guisnet M, Costa L, Ribeiro FR (2009) Prevention of zeolite deactivation by coking. J Mol Catal A Chem 305:69–83. https://doi.org/10.1016/j.molcata.2008.11.012 Hadi N, Niaei A, Alizadeh R, Raeisipour J (2018) Durable and highly selective tungsten-substituted MFI metallosilicate catalysts for the methanol-to-propylene process by designing a novel feed-supply technique. Comptes Rendus Chimie 21:523–540. https://doi.org/10.1016/j.crci.2018.01.001 Hafeez S, Al-Salem SM, Manos G, Constantinou A (2020) Fuel production using membrane reactors: a review. Environ Chem Lett 18:1477–1490 Hamid MYS, Firmansyah ML, Triwahyono S, et al (2017) Oxygen vacancy-rich mesoporous silica KCC-1 for CO2 methanation. Appl Catal A Gen 532:86–94. https://doi.org/10.1016/j.apcata.2016.12.023 Han J, Yang G, Ding H, Chen X (2021a) Revealing inherent factors of SAPO-34 zeolites etching towards the fabrication of hierarchical structure. Microporous and Mesoporous Materials 319:. https://doi.org/10.1016/j.micromeso.2021.111067 Han L, Guo L, Xue S, et al (2021b) Polyacrylamide-assisted synthesis of hierarchical porous SAPO-34 zeolites with excellent MTO catalytic performance. Microporous and Mesoporous Materials 311:. https://doi.org/10.1016/j.micromeso.2020.110676 Hasnain Bakhtiar S, Ismail A, Ali S, et al (2024) Tuning the acidity of SAPO-34 zeolite through niobium incorporation for enhanced catalytic performance during MTO reaction. Inorg Chem Commun 159:. https://doi.org/10.1016/j.inoche.2023.111835 Hatta AH, Jalil AA, Hamid MYS, et al (2023) The interparticle oxygen vacancies enrichment in the matrix of fibrous silica ceria supported nickel for CO methanation. Fuel 333:. https://doi.org/10.1016/j.fuel.2022.126539 Helveg S, Sehested J, Rostrup-Nielsen JR (2011) Whisker carbon in perspective. Catal Today 178:42–46. https://doi.org/10.1016/j.cattod.2011.06.023 Hsu CS, Robinson PR (2019) Petrochemicals. In: Petroleum Science and Technology. Springer International Publishing, Cham, pp 345–383 Hussain I, Jalil AA, Fatah NAA, et al (2020a) Cockscomb-like fibrous silica beta zeolite (FSBEA) as a new engineered catalyst for enhanced CO methanation. In: IOP Conference Series: Materials Science and Engineering. Institute of Physics Publishing Hussain I, Jalil AA, Fatah NAA, et al (2020b) Cockscomb-like fibrous silica beta zeolite (FSBEA) as a new engineered catalyst for enhanced CO methanation. In: IOP Conference Series: Materials Science and Engineering. Institute of Physics Publishing Hussain I, Jalil AA, Hassan NS, et al (2020c) Fabrication and characterization of highly active fibrous silica-mordenite (FS@SiO2-MOR) cockscomb shaped catalyst for enhanced CO2 methanation. Chem Eng Sci 228:. https://doi.org/10.1016/j.ces.2020.115978 Hussain I, Jalil AA, Mamat CR, et al (2019) New insights on the effect of the H2/CO ratio for enhancement of CO methanation over metal-free fibrous silica ZSM-5: Thermodynamic and mechanistic studies. Energy Convers Manag 199:. https://doi.org/10.1016/j.enconman.2019.112056 Izan SM, Jalil AA, Hitam CKNLCK, Nabgan W (2020) Influence of Nitrate and Phosphate on Silica Fibrous Beta Zeolite Framework for Enhanced Cyclic and Noncyclic Alkane Isomerization. Inorg Chem 59:1723–1735. https://doi.org/10.1021/acs.inorgchem.9b02914 Jin W, Wang B, Tuo P, et al (2018) Selective Desilication, Mesopores Formation, and MTO Reaction Enhancement via Citric Acid Treatment of Zeolite SAPO-34. Ind Eng Chem Res 57:4231–4236. https://doi.org/10.1021/acs.iecr.8b00632 Lais A, Gondal MA, Dastageer MA (2018) Semiconducting oxide photocatalysts for reduction of CO2 to methanol. Environ Chem Lett 16:183–210 Lal B, Pal DB, Rathoure AK, Singh A (2021) Studies on acidity and activity of kaolin-supported Ag-doped HZSM–5 in methanol to olefins process. Biomass Convers Biorefin. https://doi.org/10.1007/s13399-021-01666-9 Liu F, Wang X, Xu F, et al (2017) Fabrication and characterization of composites comprising (CHA)SAPO-34 with (MFI)ZSM-5 topologies and their catalytic performances on MTO reaction. Microporous and Mesoporous Materials 252:197–206. https://doi.org/10.1016/j.micromeso.2016.02.024 Liu G, Tian P, Li J, et al (2008) Synthesis, characterization and catalytic properties of SAPO-34 synthesized using diethylamine as a template. Microporous and Mesoporous Materials 111:143–149. https://doi.org/10.1016/j.micromeso.2007.07.023 Minova IB, Barrow NS, Sauerwein AC, et al (2021) Silicon redistribution, acid site loss and the formation of a core–shell texture upon steaming SAPO-34 and their impact on catalytic performance in the Methanol-to-Olefins (MTO) reaction. J Catal 395:425–444. https://doi.org/10.1016/j.jcat.2021.01.012 Mohammadrezaei A, Papari S, Asadi M, et al (2012) Methanol to propylene: The effect of iridium and iron incorporation on the HZSM-5 catalyst. Front Chem Sci Eng 6:253–258. https://doi.org/10.1007/s11705-012-0902-4 Numpilai T, Kahadit S, Witoon T, et al (2021) CO2 Hydrogenation to Light Olefins Over In2O3/SAPO-34 and Fe-Co/K-Al2O3 Composite Catalyst. Top Catal 64:316–327. https://doi.org/10.1007/s11244-021-01412-5 Olsbye U, Svelle S, Bjrgen M, et al (2012) Conversion of methanol to hydrocarbons: How zeolite cavity and pore size controls product selectivity. Angewandte Chemie - International Edition 51:5810–5831 Owgi AHK, Jalil AA, Aziz MAA, et al (2023) Methane dry reforming on fibrous silica-alumina employing nanocrystals of nickel and cobalt to recognize the most efficient metal. Int J Hydrogen Energy. https://doi.org/10.1016/j.ijhydene.2023.05.004 Polshettiwar V, Cha D, Zhang X, Basset JM (2010) High-surface-area silica nanospheres (KCC-1) with a fibrous morphology. Angewandte Chemie - International Edition 49:9652–9656. https://doi.org/10.1002/anie.201003451 Qureshi ZS, Jaseer EA (2020) Effective and selective direct aminoformylation of nitroarenes utilizing palladium nanoparticles assisted by fibrous-structured silica nanospheres. Research on Chemical Intermediates 46:4279–4295. https://doi.org/10.1007/s11164-020-04206-8 Rahman AFA, Jalil AA, Hamid MYS, et al (2022) Improved ethylbenzene suppression and coke-resistance on benzene methylation over metals doped fibrous silica-HZSM-5 zeolite. Molecular Catalysis 526:. https://doi.org/10.1016/j.mcat.2022.112370 Ren S, Liu G, Wu X, et al (2017) Enhanced MTO performance over acid treated hierarchical SAPO-34. Cuihua Xuebao/Chinese Journal of Catalysis 38:123–130. https://doi.org/10.1016/S1872-2067(16)62557-3 Ren T, Patel M, Blok K (2006) Olefins from conventional and heavy feedstocks: Energy use in steam cracking and alternative processes. Energy 31:425–451. https://doi.org/10.1016/j.energy.2005.04.001 Sadrameli SM (2016) Thermal/catalytic cracking of liquid hydrocarbons for the production of olefins: A state-of-the-art review II: Catalytic cracking review. Fuel 173:285–297 Simakov DSA, Wright MM, Ahmed S, et al (2015) Solar thermal catalytic reforming of natural gas: A review on chemistry, catalysis and system design. Catal Sci Technol 5:1991–2016. https://doi.org/10.1039/c4cy01333f Soheili S, Nakhaei Pour A, Mohammadi A (2021) SAPO-34 synthesis by combinations of structure-directing agents: Experimental and Monte Carlo simulations studies. Microporous and Mesoporous Materials 317:. https://doi.org/10.1016/j.micromeso.2021.111003 Soltanali S, Darian JT (2019) Synthesis of mesoporous SAPO-34 catalysts in the presence of MWCNT, CNF, and GO as hard templates in MTO process. Powder Technol 355:127–134. https://doi.org/10.1016/j.powtec.2019.07.008 Stö M (1999) Methanol-to-hydrocarbons: catalytic materials and their behavior1 Sun C, Wang Y, Zhao A, et al (2020) Synthesis of nano-sized SAPO-34 with morpholine-treated micrometer-seeds and their catalytic performance in methanol-to-olefin reactions. Appl Catal A Gen 589:. https://doi.org/10.1016/j.apcata.2019.117314 Sun Q, Wang N, Guo G, et al (2015) Synthesis of tri-level hierarchical SAPO-34 zeolite with intracrystalline micro-meso-macroporosity showing superior MTO performance. J Mater Chem A Mater 3:19783–19789. https://doi.org/10.1039/c5ta04642d Sun Q, Wang N, Xi D, et al (2014) Organosilane surfactant-directed synthesis of hierarchical porous SAPO-34 catalysts with excellent MTO performance. Chemical Communications 50:6502–6505. https://doi.org/10.1039/c4cc02050b Sun Q, Xie Z, Yu J (2018) The state-of-the-art synthetic strategies for SAPO-34 zeolite catalysts in methanol-to-olefin conversion. Natl Sci Rev 5:542–558 Teh LP, Triwahyono S, Jalil AA, et al (2016) Fibrous silica mesoporous ZSM-5 for carbon monoxide methanation. Appl Catal A Gen 523:200–208. https://doi.org/10.1016/j.apcata.2016.05.031 Valecillos J, Epelde E, Albo J, et al (2020) Slowing down the deactivation of H-ZSM-5 zeolite catalyst in the methanol-to-olefin (MTO) reaction by P or Zn modifications. Catal Today 348:243–256. https://doi.org/10.1016/j.cattod.2019.07.059 Varzaneh AZ, Towfighi J, Mohamadalizadeh A (2014) Comparative study of naphtha cracking over SAPO-34 and HZSM-5: Effects of cerium and zirconium on the catalytic performance. J Anal Appl Pyrolysis 107:165–173. https://doi.org/10.1016/j.jaap.2014.02.017 Varzaneh AZ, Towfighi J, Sahebdelfar S (2016) Carbon nanotube templated synthesis of metal containing hierarchical SAPO-34 catalysts: Impact of the preparation method and metal avidities in the MTO reaction. Microporous and Mesoporous Materials 236:1–12. https://doi.org/10.1016/j.micromeso.2016.08.027 Wang P, Yang D, Hu J, et al (2013) Synthesis of SAPO-34 with small and tunable crystallite size by two-step hydrothermal crystallization and its catalytic performance for MTO reaction. In: Catalysis Today Wang Q, Wang X, Dai W, et al (2023) Core-shell SAPO-34@ZSM-5 composite via in situ solid-solid transformation of pre-coating MCM-41 shell and its application in methanol-to-olefins. Microporous and Mesoporous Materials 353:. https://doi.org/10.1016/j.micromeso.2023.112498 Wu L, Hensen EJM (2014) Comparison of mesoporous SSZ-13 and SAPO-34 zeolite catalysts for the methanol-to-olefins reaction. Catal Today 235:160–168. https://doi.org/10.1016/j.cattod.2014.02.057 Wu W, Guo W, Xiao W, Luo M (2011) Dominant reaction pathway for methanol conversion to propene over high silicon H-ZSM-5. Chem Eng Sci 66:4722–4732. https://doi.org/10.1016/j.ces.2011.06.036 Yang Y, Sun C, Du J, et al (2012) The synthesis of endurable B-Al-ZSM-5 catalysts with tunable acidity for methanol to propylene reaction. Catal Commun 24:44–47. https://doi.org/10.1016/j.catcom.2012.03.013 Yaripour F, Shariatinia Z, Sahebdelfar S, Irandoukht A (2015) Effect of boron incorporation on the structure, products selectivities and lifetime of H-ZSM-5 nanocatalyst designed for application in methanol-to-olefins (MTO) reaction. Microporous and Mesoporous Materials 203:41–53. https://doi.org/10.1016/j.micromeso.2014.10.024 Zapater D, Lasobras J, Soler J, et al (2021) MTO with SAPO-34 in a Fixed-Bed Reactor: Deactivation Profiles. Ind Eng Chem Res 60:16162–16170. https://doi.org/10.1021/acs.iecr.1c02718 Zhang J, Xu L, Zhang Y, et al (2018) Hydrogen transfer versus olefins methylation: On the formation trend of propene in the methanol-to-hydrocarbons reaction over Beta zeolites. J Catal 368:248–260. https://doi.org/10.1016/j.jcat.2018.10.015 Zhang L, Wang H, Liu G, et al (2016) Methanol-to-olefin conversion over H-MCM-22 catalyst. J Mol Catal A Chem 411:311–316. https://doi.org/10.1016/j.molcata.2015.11.013 Zhang W, Fan S, Zhang J, et al (2019) Transformation of LPG on HZSM-5 catalyst: Effects of tuned pores and acidity on product distribution. Fuel 254:. https://doi.org/10.1016/j.fuel.2019.06.023 Zheng T, Liu H, He P, et al (2022) Post synthesis of hierarchical SAPO-34 via citric acid etching: Mechanism of selective desilication. Microporous and Mesoporous Materials 335:. https://doi.org/10.1016/j.micromeso.2022.111798 Zhou J, Zhang J, Zhi Y, et al (2018) Partial Regeneration of the Spent SAPO-34 Catalyst in the Methanol-to-Olefins Process via Steam Gasification. Ind Eng Chem Res 57:17338–17347. https://doi.org/10.1021/acs.iecr.8b04181 Supplementary Files Supplementarymaterial.docx Cite Share Download PDF Status: Published Journal Publication published 21 May, 2025 Read the published version in Environmental Chemistry Letters → Version 1 posted Reviewers agreed at journal 12 Jul, 2024 Reviewers invited by journal 08 Jul, 2024 Editor assigned by journal 25 Jun, 2024 First submitted to journal 24 Jun, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4631428","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":324239434,"identity":"36ad9b01-10a8-4c6c-8911-d94b03001388","order_by":0,"name":"Muhammad Hafizuddin Mohd Sofi","email":"","orcid":"","institution":"Universiti Teknologi Malaysia","correspondingAuthor":false,"prefix":"","firstName":"Muhammad","middleName":"Hafizuddin Mohd","lastName":"Sofi","suffix":""},{"id":324239435,"identity":"517c6244-7730-4c51-97d9-580f4d47f5d7","order_by":1,"name":"Muhamed Yusuf Shahul Hamid","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAlElEQVRIiWNgGAWjYPACOTmStRgbM7CRqiWxgWgtug08ZpI/2wzSN9zvTmC62UaEFrMDPGbSvG0GuRuO8W5gziVaC2PbHxK1gB1mQJIWCaDDEkjQcpit2JrnnIHhzGO5Gw7nnCNGy/HmjTd/lBnI8x0+u/FxThkRWhiYOQzg7AOMxEUO+wMkzh+itIyCUTAKRsEIAwAoKDMhz4fxYQAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0003-4770-1392","institution":"Universiti Teknologi Malaysia - Main Campus Skudai: Universiti Teknologi Malaysia","correspondingAuthor":true,"prefix":"","firstName":"Muhamed","middleName":"Yusuf Shahul","lastName":"Hamid","suffix":""},{"id":324239436,"identity":"ec724aba-d5ef-40a4-802f-d854bf10fdbe","order_by":2,"name":"Aishah Abdul Jalil","email":"","orcid":"","institution":"Universiti Teknologi Malaysia","correspondingAuthor":false,"prefix":"","firstName":"Aishah","middleName":"Abdul","lastName":"Jalil","suffix":""},{"id":324239437,"identity":"baaee405-be94-4c8f-8c87-752e7fb5f444","order_by":3,"name":"Tuan Amran Tuan Abdullah","email":"","orcid":"","institution":"Universiti Teknologi Malaysia","correspondingAuthor":false,"prefix":"","firstName":"Tuan","middleName":"Amran Tuan","lastName":"Abdullah","suffix":""},{"id":324239438,"identity":"7104f755-ca7e-421c-9fae-d8dcb3df6c3c","order_by":4,"name":"Mohamed Yusuf Mohamud","email":"","orcid":"","institution":"Universiti Teknologi Malaysia","correspondingAuthor":false,"prefix":"","firstName":"Mohamed","middleName":"Yusuf","lastName":"Mohamud","suffix":""},{"id":324239439,"identity":"a72eca7d-d8d9-4374-906c-814c0f5cbbb7","order_by":5,"name":"Mahadi Bahari","email":"","orcid":"","institution":"Universiti Teknologi Malaysia","correspondingAuthor":false,"prefix":"","firstName":"Mahadi","middleName":"","lastName":"Bahari","suffix":""},{"id":324239440,"identity":"4998d479-fe68-4843-88f1-0b80fe2db7f0","order_by":6,"name":"Nurul Sahida Hassan","email":"","orcid":"","institution":"Universiti Teknologi Malaysia","correspondingAuthor":false,"prefix":"","firstName":"Nurul","middleName":"Sahida","lastName":"Hassan","suffix":""},{"id":324239441,"identity":"260a9be1-c7ec-49cd-83e6-ecf445ddfffd","order_by":7,"name":"Dai-Viet N. Vo","email":"","orcid":"","institution":"Nguyen Tat Thanh University","correspondingAuthor":false,"prefix":"","firstName":"Dai-Viet","middleName":"N.","lastName":"Vo","suffix":""}],"badges":[],"createdAt":"2024-06-24 16:13:55","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4631428/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4631428/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10311-025-01845-4","type":"published","date":"2025-05-21T15:58:05+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":62139959,"identity":"34a5b03e-7cbc-41f0-945f-2b33cc43af52","added_by":"auto","created_at":"2024-08-09 16:57:19","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":54640,"visible":true,"origin":"","legend":"\u003cp\u003e(\u003cstrong\u003ea\u003c/strong\u003e) X-ray diffraction (XRD) pattern, (\u003cstrong\u003eb\u003c/strong\u003e)\u0026nbsp;Fourier transform infrared spectroscopy-potassium bromide (FTIR-KBr) spectra, (\u003cstrong\u003ec\u003c/strong\u003e) N\u003csub\u003e2\u003c/sub\u003e physisorption, and (\u003cstrong\u003ed\u003c/strong\u003e) non-local density functional theory (NLDFT) pore size distribution of commercial SAPO-34 and fibrous silica-wrapped SAPO-34 (FSAPO-34). Observe that the fibrous silica-wrapped SAPO-34 (FSAPO-34) exhibits significant N\u003csub\u003e2\u003c/sub\u003e uptake at higher relative pressures, along with a pronounced peak at a pore width of 5 nm, suggesting the formation of larger mesopores attributed to its fibrous dendrimeric structure.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4631428/v1/8d729950982233e473a056f8.png"},{"id":62139960,"identity":"7521dd0d-4f75-42c2-9393-f56cc368d2c9","added_by":"auto","created_at":"2024-08-09 16:57:20","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":292432,"visible":true,"origin":"","legend":"\u003cp\u003eField emission scanning electron microscopy (FESEM) images of (\u003cstrong\u003ea\u003c/strong\u003e) commercial SAPO-34 and (\u003cstrong\u003eb-d\u003c/strong\u003e) fibrous silica-wrapped SAPO-34 (FSAPO-34) and (\u003cstrong\u003ee-g\u003c/strong\u003e) transmission electron microscopy (TEM) images coupled with (\u003cstrong\u003eh\u003c/strong\u003e) energy dispersive X-ray (EDX) mapping for FSAPO-34. Note that the successful development of fibrous silica on the SAPO-34 surface was achieved by using the microemulsion technique and the zeolite seed-assisted method.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4631428/v1/729ee57d38e06e8bd345147b.png"},{"id":62139962,"identity":"9a4737ef-d9ec-4ffe-97e9-e6239e8e5763","added_by":"auto","created_at":"2024-08-09 16:57:20","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":84808,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4631428/v1/09ecb70fc636d01bf87fe082.png"},{"id":62139961,"identity":"54a43318-8bfe-40b7-99d8-5a12ed4fe3c5","added_by":"auto","created_at":"2024-08-09 16:57:20","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":164637,"visible":true,"origin":"","legend":"\u003cp\u003e(\u003cstrong\u003ea\u003c/strong\u003e) Thermal gravimetric analysis (TGA), (\u003cstrong\u003eb\u003c/strong\u003e) derivative thermogravimetry (DTG) curve, (\u003cstrong\u003ec\u003c/strong\u003e) oxygen temperature-programmed oxidation (O\u003csub\u003e2\u003c/sub\u003e-TPO) profiles, (\u003cstrong\u003ed\u003c/strong\u003e) Raman spectra\u0026nbsp;of spent SAPO-34 and fibrous silica-wrapped SAPO-34 (FSAPO-34) catalysts, and (\u003cstrong\u003ee-f\u003c/strong\u003e) transmission electron microscopy (TEM) images of spent FSAPO-34. Note that the spent fibrous silica-wrapped SAPO-34 (FSAPO-34) shows less formation of coke due to its unique mesoporous fibrous structure compared to the spent SAPO-34 while also maintaining its morphology and preserving its fibrous nature after 30 hours of stability test.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4631428/v1/098605216d2d760fed2f09f0.png"},{"id":83460198,"identity":"06f42ef0-f625-4cd6-b00a-ea47db318027","added_by":"auto","created_at":"2025-05-26 16:11:54","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1408312,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4631428/v1/6b917292-13f7-453a-9626-ff46da406403.pdf"},{"id":62139963,"identity":"bf74e32e-b6d5-4d72-bb01-2ec2d3fd93c3","added_by":"auto","created_at":"2024-08-09 16:57:20","extension":"docx","order_by":6,"title":"","display":"","copyAsset":false,"role":"supplement","size":1359614,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementarymaterial.docx","url":"https://assets-eu.researchsquare.com/files/rs-4631428/v1/af9ac09f9e212ef1c493735f.docx"}],"financialInterests":"","formattedTitle":"Enhanced coke resistance in methanol to olefins reaction via surplus mesoporosity of fibrous silica-wrapped SAPO-34","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eLight olefins, specifically ethylene and propylene, play a crucial role in the chemical industry as they are widely utilized commodities with diverse applications (Mohammadrezaei et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Hsu and Robinson \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Zapater et al. \u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Conventionally, light olefins are primarily generated through the thermal cracking of crude oil and naphtha as a feedstock (Chen et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). This thermal cracking process typically involves high operating temperatures, necessitating a substantial amount of energy, leading to significant emissions of CO\u003csub\u003e2\u003c/sub\u003e and CO (Ren et al. \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Sadrameli \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Lal et al. \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). In addition, the depleting availability of reserves and the increasing costs of crude oil reduce the viability of this process (Liu et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Sun et al. \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Lal et al. \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe significant increase in global energy demand, along with environmental concerns, has propelled researchers to explore alternative methods for light olefin production as a replacement for the current fossil fuel-based process (Hafeez et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Deka et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). In response to the shift towards a more sustainable future, the methanol-to‐olefin (MTO) reaction has proven to be a successful non‐petroleum pathway to generate light olefins and become important to worldwide catalytic technologies that rely on abundant resources such as CO\u003csub\u003e2,\u003c/sub\u003e coal, natural gas, and biomass with methanol serving as the intermediate compound (Lais et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Sun et al. \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Valecillos et al. \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Minova et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eZeolite has been widely used as the most important solid heterogeneous catalysts in several industrial processes, including methanol conversion to light olefins, due to their excellent shape selectivity and exceptional characteristics of their active sites (Guisnet et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Zhang et al. \u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Garc\u0026iacute;a-Ruiz et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Among the different types of zeolites, silico-alumino-phosphate (SAPO) zeolite SAPO-34 is considered as the epitome catalyst for MTO reaction due to its capability to yield high selectivity of ethylene and propylene (Bakhtiar et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). This is attributed to the inherent characteristics of SAPO-34, which features an appropriate acidity with CHA (Chabazite) supercages consisting of small 8-membered ring pore aperture (3.8 \u0026Aring; \u0026times; 3.8 \u0026Aring;) (Liu et al. \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2008\u003c/span\u003e, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eHowever, despite the impressive catalytic performance exhibited by SAPO-34 in MTO reactions, it comes with a significant drawback, which is rapid deactivation. The narrow pore aperture of SAPO-34 hinders the mass transport and diffusion of bulky molecules as intermediate products. This obstruction leads to the blockage of the microporous channels of the catalyst and coverage of the acidic active sites due to coke deposition, resulting in the deactivation of the catalyst (Jin et al. \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Soltanali and Darian \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Consequently, SAPO-34 catalysts have short catalytic lifetimes and require continuous regeneration (Zhou et al. \u003cspan citationid=\"CR75\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Zapater et al. \u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Hence, the challenge lies in effectively controlling and mitigating coking formation while simultaneously preserving or improving its catalytic performance in developing SAPO-34 catalysts.\u003c/p\u003e \u003cp\u003eIn the past few years, various strategies have been taken into action to overcome the inherent diffusion limitation to reduce the coke deposition and consequently increase catalyst lifetime, such as reducing the crystal size and creating a hierarchical structure. For instance, Wang et al. prepared a range of SAPO-34 catalysts with different crystal sizes (160\u0026ndash;1100 nm) by a two-step hydrothermal crystallization which shows that SAPO-34 with smaller crystal sizes exhibits superior catalytic activity and stability (Wang et al. \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eCommonly, hierarchical pore structures are achieved by either pre-synthesis using multiple structure directing agents or post-synthesis treatment using different types of acid (Sun et al. \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Ren et al. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Han et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2021b\u003c/span\u003e; Zheng et al. \u003cspan citationid=\"CR74\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Both approaches successfully introduce mesopores and macropores into microporous SAPO-34, which led to excellent MTO catalytic performance with a suppressed coke deposition and a longer catalytic lifetime.\u003c/p\u003e \u003cp\u003eAlthough there has been a notable development in modifying pure microporous zeolite using the aforementioned method, the creation of secondary porosities always contributes to the destruction of some micropore structures, resulting in structural defects (Wang et al. \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). In recent times, introducing a hierarchical structure in microporous zeolites through the formation of a core and shell catalyst has gained significant interest among researchers in this field. For example, Chen et al. report a novel method to synthesize ZSM-5 as a core with SAPO-34 layer on the surface by introducing ZSM-5 into the synthesis gel of SAPO-34 under hydrothermal conditions (Chen et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Wang et al. took a different approach by coating the SAPO-34 core with an MCM-41 shell, which was then transformed into a ZSM-5 shell through in situ solid-solid transformation (Wang et al. \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The combined benefits of a hierarchical pore system and distinct zeolite phases have resulted in the core-shell composite catalyst exhibiting exceptional catalytic performance and lifetime.\u003c/p\u003e \u003cp\u003eBesides the selective shell, an inert shell such as KAUST Catalysis Center-1 (KCC-1, also known as fibrous silica) has been utilized to construct core-shell zeolite. Polshettiwar et al. were the first to introduce this novel morphology with distinct properties which is considered a promising alternative for creating a new zeolite structure (Polshettiwar et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). This fact was supported by excellent performances of fibrous silica mesoporous zeolite due to high surface area and mesopore volume, resulting in high accessibility and low diffusion limitations, as shown in various catalytic reactions such as cumene hydrocracking (Firmansyah et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), toluene methylation (Ghani et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), cyclic and noncyclic alkane isomerization (Izan et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), and CO\u003csub\u003e2\u003c/sub\u003e methanation (Hussain et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2020c\u003c/span\u003e). Inspired by this discovery, we synthesized fibrous silica-wrapped SAPO-34 (FSAPO-34) for the first time and investigated its physicochemical properties along with its catalytic performance in the MTO reaction.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Chemicals and Materials\u003c/h2\u003e \u003cp\u003eThe commercial SAPO-34 was purchased from ZR Catalyst Co., Ltd, while cetyltrimethylammonium bromide (CTAB, (C\u003csub\u003e16\u003c/sub\u003eH\u003csub\u003e33\u003c/sub\u003e)N(CH\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003eBr, \u0026gt;\u0026thinsp;98%), urea (CH\u003csub\u003e4\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eO, \u0026gt;\u0026thinsp;99.5%), toluene (C\u003csub\u003e7\u003c/sub\u003eH\u003csub\u003e8\u003c/sub\u003e, 98%), 1-butanol (C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e10\u003c/sub\u003eO, 98%), tetraethyl orthosilicate (TEOS, Si(OC\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e, \u0026gt;\u0026thinsp;98%) and methanol (CH\u003csub\u003e3\u003c/sub\u003eOH, 99.5%) were purchased from Merck. The hydrogen (H\u003csub\u003e2\u003c/sub\u003e, 99.5%), nitrogen (N\u003csub\u003e2\u003c/sub\u003e, 99.5%), and compressed air (\u0026gt;\u0026thinsp;90%) cylindrical gas tanks were purchased from Mega Mount Industrial Gases. All compounds and chemicals were utilized as purchased without undergoing any additional purifying processes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Catalyst preparation\u003c/h2\u003e \u003cp\u003eFibrous silica-wrapped SAPO-34 was synthesized using the microemulsion method in combination with the zeolite seed-assisted method using commercial SAPO-34. The fibrous silica-wrapped SAPO-34 was prepared with initial molar ratio parameters of urea : CTAB : toluene : 1-butanol : H\u003csub\u003e2\u003c/sub\u003eO : seed : TEOS\u0026thinsp;=\u0026thinsp;0.98 : 0.27 : 27.58 : 1.6 : 152.52 : 0.38. Initially, the CTAB that acts as a structure-directing agent and urea were dissolved in distilled water, followed by adding toluene and 1-butanol while maintaining stirrer condition at room temperature. After obtaining a homogeneous solution, the commercial SAPO-34 seed was introduced to the mixture before being stirred vigorously for another hour while maintaining the same temperature. Then, TEOS was dropwise introduced to the mixture and stirred for four hours. Subsequently, the obtained mixture was exposed to intermittent microwave radiation (400 W) for eight hours. The solid product was collected through centrifugation at a speed of 4000 rpm and thoroughly rinsed with distilled water several times. Finally, the resulting product was dried at 120\u0026deg;C overnight and calcined at 550\u0026deg;C for six hours to eliminate the structure-directing agent.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Catalyst characterization\u003c/h2\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.3.1 Characterization of fresh catalyst\u003c/h2\u003e \u003cp\u003eThe fresh catalysts under study were analyzed using various characterization methods. The analysis of catalyst crystalline structure was carried out using an X-ray diffractometer (XRD) (Bruker Advanced D8 X-ray) equipped with Cu Kα radiation (λ\u0026thinsp;=\u0026thinsp;1.5406 \u0026Aring;), 2θ scan range of 5\u0026deg;-40\u0026deg;, scanning rate of 45 kV and step size of 40 mA. To identify the functional groups on the catalysts, the Fourier transform infrared spectroscopy with potassium bromide (FTIR-KBr) method was employed using an Agilent Cary 640 spectrometer, with 5 sample scans conducted at a resolution of 5 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. N\u003csub\u003e2\u003c/sub\u003e physisorption studies on the catalysts were performed using a Beckman Coulter SA 3100 instrument. The surface area and pore volume were computed using the Brunauer\u0026ndash;Emmett\u0026ndash;Teller (BET) method, while the pore size distribution was determined using non-local density functional theory (NLDFT). In addition, the acidity of the catalysts was examined through the ammonia temperature-programmed desorption (NH\u003csub\u003e3\u003c/sub\u003e-TPD) technique utilizing Micromeritics Chemisorb 2720 Pulse Chemisorption equipment. The chemical compositions of samples were analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES) (PerkinElmer, Inc., Shelton, CT, USA). The morphological properties of the catalyst were analyzed using field emission scanning electron microscopy (FESEM) (JEOL JSM- 6701F, Japan) and transmission electron microscopy (TEM) (Philips EM420, USA).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.3.2 Characterization of spent catalyst.\u003c/h2\u003e \u003cp\u003eThe spent catalysts undergo several characterization techniques. The amount of carbon deposited on the spent catalyst was assessed using thermal gravimetric analysis (TGA) conducted with a Mettler Toledo (SDTA-851) instrument in the air stream. The nature of carbon deposits on the spent catalyst was examined using the Renishaw Raman spectroscopy instrument. To characterize the carbon deposited on the spent catalyst, the oxygen temperature-programmed oxidation (O\u003csub\u003e2\u003c/sub\u003e-TPO) of catalysts was performed using the Micromeritics Chemisorb 2720 equipment. Transmission electron microscopy was utilized to study the morphology of the spent catalyst using the same equipment as fresh catalyst characterization.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Catalytic testing\u003c/h2\u003e \u003cp\u003eThe catalytic performance was performed using a micro-catalytic reactor. Prior to catalytic testing, 0.25 g of sieved catalyst was placed in an 8 mm quartz tube. The catalyst was treated by exposed to a compressed air stream (120 mL/min) at 450\u0026deg;C for 60 minutes. For catalytic performance, 0.03 ml methanol was injected into the treated catalyst with N\u003csub\u003e2\u003c/sub\u003e as the carrier gas at a 70 mL/min flow rate. Meanwhile, methanol was continuously introduced to the catalyst for evaluating catalytic lifetime using an automatic syringe pump at a weight hourly space velocity of 6.9 h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, maintaining the same N\u003csub\u003e2\u003c/sub\u003e flow rate. The resulting products were examined using an Agilent Gas Chromatography 7820A FID fitted with an HP-5 capillary column. The catalytic performance was evaluated at different temperature ranges of 300 to 500\u0026deg;C, and the stability of the catalyst was assessed at a constant temperature of 500\u0026deg;C over time on stream of 30 hours. The methanol conversion, selectivity, and yield were calculated by equations (1), (2), and (3), respectively (Hadi et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$Methanol conversion \\left(\\%\\right)= \\frac{{N}_{MeOH in}- {N}_{MeOH out}}{{N}_{MeOH in}}\\times 100 \\left(1\\right)$$\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$Hydrocarbon selectivity \\left(\\%\\right)= \\frac{{N}_{Ci}}{{N}_{MeOH in}- {N}_{MeOH out}}\\times 100 \\left(2\\right)$$\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equc\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equc\" name=\"EquationSource\"\u003e\n$$Yield \\left(\\%\\right)= \\frac{methanol conversion \\times hydrocarbon selectivity}{100} \\left(3\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere N is the number of moles. The subscripts \u003csub\u003eMeOH in\u003c/sub\u003e and \u003csub\u003eMeOH out\u003c/sub\u003e represent the methanol inlet and outlet of the reactor, respectively. The term N\u003csub\u003eMeOH in\u003c/sub\u003e \u0026ndash; N\u003csub\u003eMeOH out\u003c/sub\u003e refers to the reacted moles of methanol. Subscript \u003csub\u003eCi\u003c/sub\u003e indicates the individual hydrocarbon produced in the MTO reaction.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e\u003cb\u003e3.1. Characterization of fresh catalysts\u003c/b\u003e\u003c/h2\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e3.1.1. Crystallinity, functional group, and textural analysis\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003ea shows the wide-angle X-ray diffractograms of both the commercial SAPO-34 and the synthesized FSAPO-34 catalysts. Several distinct peaks are detected at 2θ\u0026thinsp;=\u0026thinsp;9.6\u0026deg;, 13\u0026deg;, 16.3\u0026deg;, 17.9\u0026deg;, 20.9\u0026deg;, 25.1\u0026deg;, and 31\u0026deg;, which correspond to the (101), (110), (021), (003), (12\u0026ndash;1), (220) and (401) crystallographic planes, respectively, that ascribed to a typical diffraction peak of SAPO-34 (CHA-type zeolite). Both samples exhibit a rhombohedral SAPO-34 structure with the most substantial XRD diffraction peak at 2θ\u0026thinsp;=\u0026thinsp;9.6 (JCPDS file No. 01-087-1527) (Soheili et al. \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). However, the intensity of the XRD pattern of FSAPO-34 was reduced compared to that of commercial SAPO-34, which indicates a substantial loss of crystallinity during the modification process. This could be due to the growth of silica species during the formation of dendrimeric silica fiber. This phenomenon was consistent with previous studies for other fibrous silica zeolite such as fibrous silica Beta (Hussain et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e), fibrous silica ZSM-5 (Teh et al. \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), and fibrous silica MOR (Hussain et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2020c\u003c/span\u003e). Besides, a broad diffraction peak centered 2θ\u0026thinsp;=\u0026thinsp;23\u0026deg; is observed for FSAPO-34 due to the amorphous feature of the silica shell (Qureshi and Jaseer \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). This broad peak was not detected in other fibrous silica zeolite material, possibly due to the different mechanisms for the formation of dendrimeric silica fiber on the SAPO-34 surface, as depicted in \u003cb\u003eFig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e\u003c/b\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe FTIR method is frequently utillized to determine the stretching and bending vibrations of various types of bonds present in the structure of catalysts. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003eb illustrates the FTIR-KBr spectrum of commercial SAPO-34 and FSAPO-34 in a 400\u0026ndash;1400 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e frequency range. Clearly, all the examined catalysts exhibited five almost identical IR bands spanning from 400 to 1400 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The absorption peaks observed at wavenumbers of 1092 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 972 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 802 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and 467 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e correspond to the vibration of asymmetric Si-O-Si stretching, external Si-OH, symmetric Si-O-Si stretching, and Si-O-Si bending vibration, respectively (Azami et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Bahari et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). While the band at 635 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is a result of the structurally sensitive double 6-membered ring vibrations, which are distinctive features of the CHA framework (Liu et al. \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Soltanali and Darian \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). The synthesized FSAPO-34 shows a higher intensity, which is dominated by a strong band at 1092 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 802 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and 467 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, confirming the presence of silica fibers surrounding the SAPO-34 seed, consistent with XRD results. An additional peak was noticed at 960 cm\u003csup\u003e\u0026ndash;1\u003c/sup\u003e only for the FSAPO-34, which was ascribed to bending vibrations of Si-OH. This occurrence could be attributed to the increased abundance of terminal silanol groups formed during the synthesis of silica fibers.\u003c/p\u003e \u003cp\u003eThe textural characteristics of the catalysts were investigated via N\u003csub\u003e2\u003c/sub\u003e physisorption isotherms, with pore size distributions determined using non-local density functional theory (NLDFT) for clearer analysis. The commercial SAPO-34 exhibited a distinct type I isotherm, affirming the catalyst's microporous structure in accordance with IUPAC classification and aligning with findings in the literature (Chen et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; De Araujo et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Conversely, FSAPO-34 catalysts displayed a type IV isotherm with an H3 hysteresis loop, which verifies a distinctive adsorption profile for mesoporous catalysts with slit-shaped pores (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003ec) (Numpilai et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eBoth catalysts demonstrate nearly identical N\u003csub\u003e2\u003c/sub\u003e adsorption at lower relative pressure, indicating the presence of microporosity in the catalysts. However, FSAPO-34 shows a greater N\u003csub\u003e2\u003c/sub\u003e adsorption at higher relative pressures, suggesting the existence of mesopores (Hussain et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2020b\u003c/span\u003e). In addition, the N\u003csub\u003e2\u003c/sub\u003e uptake at relative pressures of 0.3 and 0.9 are assigned to intra- and interparticle pores, respectively (Hamid et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). A notable increase in N\u003csub\u003e2\u003c/sub\u003e uptake at a relative pressure of 0.9 was observed for FSAPO-34 compared to SAPO-34. This finding indicates that the fibrous silica form on the surface of SAPO-34 significantly contributed to the abundance of interparticle pores.\u003c/p\u003e \u003cp\u003eThe hysteresis loops observed in the case of FSAPO-34 substantiate the effective formation of mesopores. This observation aligns with the pore distributions derived from the NLDFT method illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003ed, which shows that a peak within the less than 2 nm range signifies the existence of micropores, whereas a peak within the greater than 2 nm range indicates the presence of mesopores. Although FSAPO-34 displayed a similar pore size distribution to SAPO-34 at a lower range (\u0026lt;\u0026thinsp;2 nm), the emergence of a broader peak in the 3\u0026ndash;6 nm range indicates the formation of larger mesopores which is undoubtedly due to fibrous dendrimeric morphology. This improvement in mesoporous characteristics could potentially improve the mass transfer properties and negate the diffusion limitations associated with the commercial SAPO-34 catalyst. Detailed information regarding the physical characteristics of SAPO-34 and FSAPO-34 are tabulated in \u003cb\u003eTable \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e\u003c/b\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003e3.1.2. Morphological studies\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003e reveals the FESEM and TEM images of SAPO-34 and FSAPO-34. From Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, it can be seen that the unmodified SAPO-34 presents the common cubic morphology, characterized by a smooth and compact surface, which is identical to the conventional SAPO-34 (Bakhtiar et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). After undergoing synthesis using the microemulsion method, the FESEM image of FSAPO-34 reveals the development of spherical silica with well-ordered dendrimeric morphology, characterized by a uniform size of 150\u0026ndash;200 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003eb-d\u003cb\u003e)\u003c/b\u003e. This distinctive spherical morphology covers the surface of the cubic particles of SAPO-34, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003ec.\u003c/p\u003e \u003cp\u003eNotably, a TEM image of FSAPO-34 (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003ee-f) shows an accumulation growth of fibrous silica on one side of the cubic SAPO-34 surface. Clearly, the EDX mapping of FSAPO-34 shows a high intensity of silica surrounding the outer surface of the core SAPO-34 (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003eh\u003cb\u003e)\u003c/b\u003e, indicating a good dispersion of fibrous silica. This result may claim the formation of a core and shell structure of FSAPO-34. In addition, a TEM image of a single fibrous silica (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003eg) further confirms the particle's spherical form, enriched with dendrimeric fibers on its external surface. These spherical morphological characteristics closely resemble those of KAUST Catalysis Center-1, as described by Polshettiwar (Polshettiwar et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). It should be noted that this result differs from other fibrous zeolite materials, where the center of the sphere consists of an aluminosilicate framework of zeolite, while the dendrimer was fully composed of silica (Teh et al. \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Abdul Jalil et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). This observation further clarifies the distinctive broad diffraction peak revealed in XRD results (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003ea) exclusively in the case of FSAPO-34.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Catalytic performance and lifetime of catalysts\u003c/h2\u003e \u003cp\u003eThe MTO reaction was carried out in a micro-catalytic reactor over the commercial SAPO-34 and synthesized FSAPO-34. The conversion of methanol, selectivity of products, and light olefins yield were displayed in \u003cb\u003eFig.\u0026nbsp;3 (a-c)\u003c/b\u003e and computed in \u003cb\u003eTable S2\u003c/b\u003e. At lower temperatures (300\u0026ndash;350\u0026deg;C), the parent catalyst shows a better conversion compared to FSAPO34. However, the conversion at higher temperatures (\u0026gt;\u0026thinsp;400\u0026deg;C) shows little disparity between both catalysts, which achieved above 95% methanol conversion. The reduced methanol conversion of FSAPO-34 can be associated with the decrease in weak acid sites, as shown in \u003cb\u003eFig. S2\u003c/b\u003e (\u003cb\u003ea-b\u003c/b\u003e), since these sites are involved in facilitating the conversion of methanol to DME as well as alkylation and methylation reactions prior to the formation of olefin products (Wu et al. \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Yang et al. \u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIt is worth mentioning that as the reaction temperature increases for both catalysts, the selectivity towards light olefins increases, where ethylene is the major product compared to propylene, accompanied by the gradual decrease of the concentration of other hydrocarbons appear among the effluents, which is similar to a pattern observed in previous work involving SAPO-34 (Castellanos-Beltran et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). The high light olefin yield was obtained over SAPO-34 at 500\u0026deg;C, which is 90.1% with a total light olefin selectivity of 93.1%, while for FSAPO-34, there was a slight 1.4% and 1.1% reduction in light olefin yield and selectivity, respectively, at the same temperature. At the lower reaction temperature (300\u0026deg;C), commercial SAPO-34 demonstrates the capability to produce a higher amount of ethylene and propylene (49.2%) compared to FSAPO-34 (15.2%). At this temperature, FSAPO-34 tends to produce more DME compared to SAPO-34, which highlights the deficiency of strong acid sites, as the olefin formation is only feasible on strong acid sites (Ghavipour et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). It is well known that the appropriate strength and amount of strong-acid sites on the surface of SAPO-34 is crucial to achieving high selectivity of light olefin, as demonstrated in the previous report (Wang et al. \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Hasnain Bakhtiar et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). The inactivity of silica fiber employed in FSAPO-34 resulted in the dilution of a strong acid site in SAPO-34 and thus led to a lower selectivity of ethylene and propylene.\u003c/p\u003e \u003cp\u003eThe catalytic lifetime of the SAPO-34 and FSAPO-34 catalysts for continuous MTO reaction was examined, and the conversion of methanol was plotted as a function of the time on stream, as illustrated in \u003cb\u003eFig.\u0026nbsp;3d\u003c/b\u003e. The catalyst lifetime was defined as the duration of continuous reaction maintaining the catalyst activity until the methanol conversion lower than 50% (Wu and Hensen \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). During the catalytic stability test, FSAPO-34 demonstrated an extended catalytic lifetime of 29.5 hours, sustaining a methanol conversion above 50% in contrast to commercial SAPO-34, which has a shorter catalytic lifetime of 19.2 hours. Although the strong acid sites of commercial SAPO-34 led to better light olefin selectivity, it also can expedite the formation of carbon-carbon bonds, leading to the generation of aromatics, which are side reactions that can cause a buildup of carbon deposits within the zeolite's pore structure (Zhang et al. \u003cspan citationid=\"CR71\" class=\"CitationRef\"\u003e2018\u003c/span\u003e, \u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). On the other hand, the microporous nature of commercial SAPO-34, as shown in N\u003csub\u003e2\u003c/sub\u003e physisorption results (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003ec), often introduces diffusion limitations for the aromatics and branched hydrocarbons formed within the pores (Wang et al. \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Han et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2021a\u003c/span\u003e). All of these factors ultimately led to the rapid deactivation of commercial SAPO-34. Thus, introducing mesopores into the synthesized FSAPO-34 structure can enhance the diffusion of products out of the pores, effectively reducing diffusion resistance, which impedes blockage of the pores caused by coke deposition (Sun et al. \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Hence, the extended stability duration observed in FSAPO-34 signifies a remarkable resistance to deactivation.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e\u003cb\u003e3.3. Analysis of spent catalysts\u003c/b\u003e\u003c/h2\u003e \u003cp\u003eCatalytic processes using zeolite-type catalysts frequently involve side reactions resulting in the development of carbonaceous material known as coke, which is the primary factor responsible for the deactivation of catalyst in the MTO reaction (Guisnet et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). The TGA and DTG analysis was used to measure the amount of coke deposits over spent SAPO-34 and FSAPO-34 catalysts at the temperature range of 30 to 900\u0026deg;C, and the results are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003e \u003cb\u003e(a-b).\u003c/b\u003e The initial weight loss at temperatures below 200\u0026deg;C is attributed to the removal of water and decomposition of volatile materials from the catalyst (Dai et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Varzaneh et al. \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The second weight loss occurring between 200 to 800\u0026deg;C primarily results from the combustion of coke deposits on the catalyst (Varzaneh et al. \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Aghamohammadi and Haghighi \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). These carbonaceous deposits can be categorized into three distinct types based on temperature ranges: 200\u0026ndash;400\u0026deg;C, 400\u0026ndash;600\u0026deg;C, and above 600\u0026deg;C. The initial range is identified as the soft coke category, characterized by a higher H/C ratio with higher combustion reactivity and a lower activation energy value. The second weight loss classifies as hard coke region with a lower H/C ratio relative to soft coke. The third category of weight loss, which occurs at temperatures exceeding 600\u0026deg;C, is referred to as laid coke. Laid coke is particularly hard to decompose in the de-coking process (Ahmed et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Aghamohammadi and Haghighi \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; D\u0026iacute;az et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIt can be seen that both SAPO-34 and FSAPO-34 showed a decrease in weight as the temperature increased \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003ea\u003cb\u003e)\u003c/b\u003e. However, the synthesized FSAPO-34 showed a weight loss of 24%, significantly lower than the 35% weight loss observed for SAPO-34, which indicates that less amount of carbon deposits formed on FSAPO-34 during MTO catalytic reaction. In addition, according to DTG curves presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003eb, the spent FSAPO-34 mostly shows a formation of hard coke within the temperature range of 400 to 600\u0026deg;C while SAPO-34 shows an additional peak at temperatures above 600\u0026deg;C implying the generation of laid coke.\u003c/p\u003e \u003cp\u003eThe O\u003csub\u003e2\u003c/sub\u003e-TPO analysis was carried out to further confirm the amount and characteristics of carbon deposition of spent SAPO-34 and FSAPO-34. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003ec shows the O\u003csub\u003e2\u003c/sub\u003e-TPO profiles over the 100\u0026ndash; 850\u0026deg;C oxidation temperature range. Similar to TGA analysis, the coke species were classified by different oxidation temperatures into three types, including C\u003csub\u003eA\u003c/sub\u003e decomposed at low temperature (350\u0026ndash;450\u0026deg;C), C\u003csub\u003eB\u003c/sub\u003e decomposed at moderate temperature (450\u0026ndash;600\u0026deg;C), and C\u003csub\u003eC\u003c/sub\u003e decomposed at high temperature (600\u0026ndash;750\u0026deg;C) (Fakeeha et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; D\u0026iacute;az et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). These sections correspond to amorphous, filaments, and graphite carbon, respectively (Hussain et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2020c\u003c/span\u003e). As expected, comparing the area of the coke-burning peak of both samples, it is evident that the area of the coke-burning peak of the SAPO-34 is substantially greater than that of the FSAPO-34 with 10.2 mmol/g\u003csub\u003eCat\u003c/sub\u003e and 2.6 mmol/g\u003csub\u003eCat\u003c/sub\u003e consumption of O\u003csub\u003e2\u003c/sub\u003e, respectively.\u003c/p\u003e \u003cp\u003eFurthermore, the maximum temperature of the coke-burning over the SAPO-34 shifted to the C\u003csub\u003eC\u003c/sub\u003e region which resulted in a more substantial peak area in the C\u003csub\u003eC\u003c/sub\u003e region compared to the FSAPO-34. The C\u003csub\u003eC\u003c/sub\u003e species is characterized by its thermal stability, making it challenging to decompose at high temperatures. Consequently, there is a possibility that this species could obstruct active sites and pores of the catalyst, leading to a reduction in the surface reaction during the MTO process (Yaripour et al. \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Liu et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). These observations are in agreement with the N\u003csub\u003e2\u003c/sub\u003e physisorption (\u003cb\u003eFig. S3\u003c/b\u003e), which shows a smaller reduction in surface area and pore volume for FSAPO-34 compared to SAPO-34 after 30 hours of continuous catalytic reaction, which indicates less carbon deposition within the surface and pores of the spent FSAPO-34.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo differentiate the various carbon species present in SAPO-34 and FSAPO-34 catalysts after 30 hours of reaction, Raman spectroscopy was utilized, and the corresponding results are illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003ed. The existence of two separate bands at 1350 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e can be ascribed to the disorder-induced band (D-band) resulting from carbon atoms bonded through sp2 hybridization and the graphite carbon band (G-band) resulting from by C-C stretching at 1590 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively. In this context, the coexistence of D and G bands indicates that both SAPO-34 and FSAPO-34 exhibited the presence of amorphous and graphite carbon during the MTO reaction. However, compared with the SAPO-34, the G band and D band spectra of the FSAPO-34 exhibit lower intensities, and this intensity of the bands reflects the quantity of carbon deposited during the reaction (Hussain et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Owgi et al. \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Hatta et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFurthermore, the degree of carbon deposit graphitization is often measured by the ratio of these two bands, known as I\u003csub\u003eG\u003c/sub\u003e/I\u003csub\u003eD\u003c/sub\u003e. A higher I\u003csub\u003eG\u003c/sub\u003e/I\u003csub\u003eD\u003c/sub\u003e ratio indicates a higher rate of graphitic carbon formation, which is a stable form of carbon deposits compared to very unstable and amorphous carbon. This led to the rapid deactivation of the catalyst and a tougher regeneration process (Rahman et al. \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The calculated value of the I\u003csub\u003eG\u003c/sub\u003e/I\u003csub\u003eD\u003c/sub\u003e ratio for FSAPO-34 and SAPO-34 was found to be 0.68 and 0.82, respectively, which confirmed that the synthesized FSAPO-34 contained less graphitic carbon than SAPO-34 owing to its distinctive fibrous structure. These observations were in accordance with the fact that FSAPO-34 displayed better stability relative to SAPO-34 during the stability test (\u003cb\u003eFig.\u0026nbsp;3d\u003c/b\u003e).\u003c/p\u003e \u003cp\u003eTEM analysis was carried out to examine the morphological characteristics of spent FSAPO-34, as depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003e (\u003cb\u003ee-f\u003c/b\u003e). As depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003ee, a portion of the fibrous silica shell has been relocated from the core SAPO-34 after 30 hours of MTO reaction. This relocation could be attributed to the aggregation of fibrous silica since it is not fully intact with the core SAPO-34, as observed in the TEM image of the fresh FSAPO-34 sample (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003ee-f).\u003c/p\u003e \u003cp\u003eHowever, it is clear that the fibrous silica structure underwent no morphological change and retained its fibrous nature after the stability test, proving the strong integrity of the fibrous silica structure (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003ef). In addition, the filamentous carbon species (whisker carbon) with similar morphology from the literature (Helveg et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Simakov et al. \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) were visible and extensively formed on the spent FSAPO-34, as evidenced by the TGA, O\u003csub\u003e2\u003c/sub\u003e-TPO, and Raman data. This type of carbon is expected to be produced from the MTO reaction since the light olefins produced from the reaction could further react to form higher olefins, paraffins, aromatics, and naphthenes through hydrogen transfer reaction or aromatization (St\u0026ouml; \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Olsbye et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). These hydrocarbons finally condense to form carbon deposition, which is usually seen as filamentous carbon deposition (Dong et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). On the basis of the above results, it is concluded that the synthesized FSAPO-34 displays a high resistance toward coke deposition, which leads to high catalytic stability in the MTO reaction due to the formation of fibrous silica on SAPO-34.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion and Future Prospects","content":"\u003cp\u003eIn conclusion, fibrous silica-wrapped SAPO-34 (FSAPO-34) with well-ordered dendrimeric morphology was successfully synthesized through microemulsion coupled with a seed-assisted synthesis method. Unlike other fibrous silica zeolite materials, fibrous silica tends to disperse on the surface of SAPO-34, as shown in morphological studies and proposed formation mechanism due to the micro-sized seed of the SAPO-34 and the inherent resistance SAPO-34 structure toward basic media. Nevertheless, the prepared FSAPO-34 introduces a unique structural feature that comes with high surface area, mesopores volume, and reduced weak and strong acidity.\u003c/p\u003e \u003cp\u003eCommercial SAPO-34 has superior catalytic performance in terms of methanol conversion and light olefins selectivity compared to FSAPO-34 at lower temperatures temperature due to reduced weak acid sites and deficiency strong acid sites in FSAPO-34, respectively. Nevertheless, when exposed to high temperatures, the FSAPO-34 can preserve its catalytic activity, showing little disparities in conversion and light olefin selectivity compared to SAPO-34, with differences of 0.3% and 1.1%, respectively.\u003c/p\u003e \u003cp\u003eThe high mesopore volume of FSAPO-34 contributes to its remarkable catalytic stability due to high accessibility and low diffusion limitations of hydrocarbon products, resulting in a 54% improvement (from 19.2 hours to 29.5 hours) compared to commercial SAPO-34. Based on the thermal gravimetric analysis, O\u003csub\u003e2\u003c/sub\u003e temperature-programmed oxidation, Raman, and transmission electron microscopy results of spent catalysts, FSAPO-34 exhibits more resistance towards coke formation compared to commercial SAPO-34. Overall, these findings position FSAPO-34 as a promising catalyst for the MTO process and provide new insight into the designing and fabricating highly efficient catalysts for light olefin production.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAcknowledgments\u003c/h2\u003e \u003cp\u003eAs authors, we are gratefully acknowledging the Universiti Teknologi Malaysia for the Fundamental Research Grant (No. 5F575).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbdul Jalil A, Zolkifli AS, Triwahyono S, et al (2019) Altering Dendrimer Structure of Fibrous-Silica-HZSM5 for Enhanced Product Selectivity of Benzene Methylation. Ind Eng Chem Res 58:553\u0026ndash;562. https://doi.org/10.1021/acs.iecr.8b03147\u003c/li\u003e\n\u003cli\u003eAghamohammadi S, Haghighi M (2019) Spray-dried zeotype/clay nanocatalyst for methanol to light olefins in fluidized bed reactor: Comparison of active and non-active filler. Appl Clay Sci 170:70\u0026ndash;85. https://doi.org/10.1016/j.clay.2019.01.006\u003c/li\u003e\n\u003cli\u003eAhmed R, Sinnathambi CM, Subbarao D (2011) Kinetics of De-coking of Spent Reforming Catalyst. Journal of Applied Sciences 11:1225\u0026ndash;1230. https://doi.org/10.3923/jas.2011.1225.1230\u003c/li\u003e\n\u003cli\u003eAzami MS, Jalil AA, Hassan NS, et al (2021) Green carbonaceous material‒fibrous silica-titania composite photocatalysts for enhanced degradation of toxic 2-chlorophenol. J Hazard Mater 414:. https://doi.org/10.1016/j.jhazmat.2021.125524\u003c/li\u003e\n\u003cli\u003eBahari MB, Mamat CR, Jalil AA, et al (2022) Enriching the methanol generation via CO2 photoconversion over the cockscomb-like fibrous silica copper. Fuel 328:. https://doi.org/10.1016/j.fuel.2022.125257\u003c/li\u003e\n\u003cli\u003eBakhtiar SUH, Wang X, Ali S, et al (2018) CTAB-assisted size controlled synthesis of SAPO-34 and its contribution toward MTO performance. Dalton Transactions 47:9861\u0026ndash;9870. https://doi.org/10.1039/C8DT01811A\u003c/li\u003e\n\u003cli\u003eCastellanos-Beltran IJ, Assima GP, Lavoie JM (2018) Effect of temperature in the conversion of methanol to olefins (MTO) using an extruded SAPO-34 catalyst. Front Chem Sci Eng 12:226\u0026ndash;238. https://doi.org/10.1007/s11705-018-1709-8\u003c/li\u003e\n\u003cli\u003eChen J, Cai R, Huang H, et al (2023) Collaborative removal of fine catalysts particles and insoluble organics from methanol-to-olefins reaction wastewater using horizontal swirl regeneration micro-channel separation (HSRMS). Process Safety and Environmental Protection 177:340\u0026ndash;354. https://doi.org/10.1016/j.psep.2023.05.059\u003c/li\u003e\n\u003cli\u003eChen X, Jiang R, Hou H, et al (2020) Synthesis of ZSM-5/SAPO-34 zeolite composites from LAPONITE\u0026reg; and their catalytic properties in the MTO reaction. CrystEngComm 22:6182\u0026ndash;6188. https://doi.org/10.1039/d0ce01002b\u003c/li\u003e\n\u003cli\u003eChen X, Vicente A, Qin Z, et al (2016) The preparation of hierarchical SAPO-34 crystals via post-synthesis fluoride etching. Chemical Communications 52:3512\u0026ndash;3515. https://doi.org/10.1039/c5cc09498d\u003c/li\u003e\n\u003cli\u003eDai W, Wu G, Li L, et al (2013) Mechanisms of the deactivation of SAPO-34 materials with different crystal sizes applied as MTO catalysts. ACS Catal 3:588\u0026ndash;596. https://doi.org/10.1021/cs400007v\u003c/li\u003e\n\u003cli\u003eDe Araujo BRS, Onrubia-Calvo JA, Stambouli I, et al (2022) Towards the development of advanced hierarchical chabazite materials: Novel micro-mesoporous silicoaluminophosphate SAPO-34 zeolites. Mater Today Commun 31:. https://doi.org/10.1016/j.mtcomm.2022.103580\u003c/li\u003e\n\u003cli\u003eDeka TJ, Osman AI, Baruah DC, Rooney DW (2022) Methanol fuel production, utilization, and techno-economy: a review. Environ Chem Lett 20:3525\u0026ndash;3554\u003c/li\u003e\n\u003cli\u003eD\u0026iacute;az M, Epelde E, Valecillos J, et al (2021) Coke deactivation and regeneration of HZSM-5 zeolite catalysts in the oligomerization of 1-butene. Appl Catal B 291:. https://doi.org/10.1016/j.apcatb.2021.120076\u003c/li\u003e\n\u003cli\u003eDong P, Shao T, Zhao Y, et al (2022) Progress of Methylation of C6-8~Arene with Methanol: Mechanism, Catalysts, Kinetic/Thermodynamics and Perspectives. Processes 10:. https://doi.org/10.3390/pr10050881\u003c/li\u003e\n\u003cli\u003eFakeeha AH, Khan WU, Al-Fatesh AS, Abasaeed AE (2013) Stabilities of zeolite-supported Ni catalysts for dry reforming of methane. Cuihua Xuebao/Chinese Journal of Catalysis 34:764\u0026ndash;768. https://doi.org/10.1016/s1872-2067(12)60554-3\u003c/li\u003e\n\u003cli\u003eFirmansyah ML, Jalil AA, Triwahyono S, et al (2016) Synthesis and characterization of fibrous silica ZSM-5 for cumene hydrocracking. Catal Sci Technol 6:5178\u0026ndash;5182. https://doi.org/10.1039/c6cy00106h\u003c/li\u003e\n\u003cli\u003eGarc\u0026iacute;a-Ruiz M, Sol\u0026iacute;s-Casados DA, Aguilar-Pliego J, et al (2020) Synthesis of 10 and 12 Ring Zeolites (MCM-22, TNU-9 and MCM-68) Modified with Zn and Its Potential Application in the Reaction of Methanol to Light Aromatics and Olefins. Top Catal 63:451\u0026ndash;467. https://doi.org/10.1007/s11244-020-01242-x\u003c/li\u003e\n\u003cli\u003eGhani NNM, Jalil AA, Triwahyono S, et al (2019) Tailored mesoporosity and acidity of shape-selective fibrous silica beta zeolite for enhanced toluene co-reaction with methanol. Chem Eng Sci 193:217\u0026ndash;229. https://doi.org/10.1016/j.ces.2018.09.009\u003c/li\u003e\n\u003cli\u003eGhavipour M, Goncalves TJ, Al Hussami R, et al (2023) Uncovering the role of Lewis and Br\u0026oslash;nsted acid sites in perforated SAPO-34 with an enhanced lifetime in methanol conversion to light olefins. New Journal of Chemistry 47:15907\u0026ndash;15921. https://doi.org/10.1039/d3nj02514d\u003c/li\u003e\n\u003cli\u003eGuisnet M, Costa L, Ribeiro FR (2009) Prevention of zeolite deactivation by coking. J Mol Catal A Chem 305:69\u0026ndash;83. https://doi.org/10.1016/j.molcata.2008.11.012\u003c/li\u003e\n\u003cli\u003eHadi N, Niaei A, Alizadeh R, Raeisipour J (2018) Durable and highly selective tungsten-substituted MFI metallosilicate catalysts for the methanol-to-propylene process by designing a novel feed-supply technique. Comptes Rendus Chimie 21:523\u0026ndash;540. https://doi.org/10.1016/j.crci.2018.01.001\u003c/li\u003e\n\u003cli\u003eHafeez S, Al-Salem SM, Manos G, Constantinou A (2020) Fuel production using membrane reactors: a review. Environ Chem Lett 18:1477\u0026ndash;1490\u003c/li\u003e\n\u003cli\u003eHamid MYS, Firmansyah ML, Triwahyono S, et al (2017) Oxygen vacancy-rich mesoporous silica KCC-1 for CO2 methanation. Appl Catal A Gen 532:86\u0026ndash;94. https://doi.org/10.1016/j.apcata.2016.12.023\u003c/li\u003e\n\u003cli\u003eHan J, Yang G, Ding H, Chen X (2021a) Revealing inherent factors of SAPO-34 zeolites etching towards the fabrication of hierarchical structure. Microporous and Mesoporous Materials 319:. https://doi.org/10.1016/j.micromeso.2021.111067\u003c/li\u003e\n\u003cli\u003eHan L, Guo L, Xue S, et al (2021b) Polyacrylamide-assisted synthesis of hierarchical porous SAPO-34 zeolites with excellent MTO catalytic performance. Microporous and Mesoporous Materials 311:. https://doi.org/10.1016/j.micromeso.2020.110676\u003c/li\u003e\n\u003cli\u003eHasnain Bakhtiar S, Ismail A, Ali S, et al (2024) Tuning the acidity of SAPO-34 zeolite through niobium incorporation for enhanced catalytic performance during MTO reaction. Inorg Chem Commun 159:. https://doi.org/10.1016/j.inoche.2023.111835\u003c/li\u003e\n\u003cli\u003eHatta AH, Jalil AA, Hamid MYS, et al (2023) The interparticle oxygen vacancies enrichment in the matrix of fibrous silica ceria supported nickel for CO methanation. Fuel 333:. https://doi.org/10.1016/j.fuel.2022.126539\u003c/li\u003e\n\u003cli\u003eHelveg S, Sehested J, Rostrup-Nielsen JR (2011) Whisker carbon in perspective. Catal Today 178:42\u0026ndash;46. https://doi.org/10.1016/j.cattod.2011.06.023\u003c/li\u003e\n\u003cli\u003eHsu CS, Robinson PR (2019) Petrochemicals. In: Petroleum Science and Technology. Springer International Publishing, Cham, pp 345\u0026ndash;383\u003c/li\u003e\n\u003cli\u003eHussain I, Jalil AA, Fatah NAA, et al (2020a) Cockscomb-like fibrous silica beta zeolite (FSBEA) as a new engineered catalyst for enhanced CO methanation. In: IOP Conference Series: Materials Science and Engineering. Institute of Physics Publishing\u003c/li\u003e\n\u003cli\u003eHussain I, Jalil AA, Fatah NAA, et al (2020b) Cockscomb-like fibrous silica beta zeolite (FSBEA) as a new engineered catalyst for enhanced CO methanation. In: IOP Conference Series: Materials Science and Engineering. Institute of Physics Publishing\u003c/li\u003e\n\u003cli\u003eHussain I, Jalil AA, Hassan NS, et al (2020c) Fabrication and characterization of highly active fibrous silica-mordenite (FS@SiO2-MOR) cockscomb shaped catalyst for enhanced CO2 methanation. Chem Eng Sci 228:. https://doi.org/10.1016/j.ces.2020.115978\u003c/li\u003e\n\u003cli\u003eHussain I, Jalil AA, Mamat CR, et al (2019) New insights on the effect of the H2/CO ratio for enhancement of CO methanation over metal-free fibrous silica ZSM-5: Thermodynamic and mechanistic studies. Energy Convers Manag 199:. https://doi.org/10.1016/j.enconman.2019.112056\u003c/li\u003e\n\u003cli\u003eIzan SM, Jalil AA, Hitam CKNLCK, Nabgan W (2020) Influence of Nitrate and Phosphate on Silica Fibrous Beta Zeolite Framework for Enhanced Cyclic and Noncyclic Alkane Isomerization. Inorg Chem 59:1723\u0026ndash;1735. https://doi.org/10.1021/acs.inorgchem.9b02914\u003c/li\u003e\n\u003cli\u003eJin W, Wang B, Tuo P, et al (2018) Selective Desilication, Mesopores Formation, and MTO Reaction Enhancement via Citric Acid Treatment of Zeolite SAPO-34. Ind Eng Chem Res 57:4231\u0026ndash;4236. https://doi.org/10.1021/acs.iecr.8b00632\u003c/li\u003e\n\u003cli\u003eLais A, Gondal MA, Dastageer MA (2018) Semiconducting oxide photocatalysts for reduction of CO2 to methanol. Environ Chem Lett 16:183\u0026ndash;210\u003c/li\u003e\n\u003cli\u003eLal B, Pal DB, Rathoure AK, Singh A (2021) Studies on acidity and activity of kaolin-supported Ag-doped HZSM\u0026ndash;5 in methanol to olefins process. Biomass Convers Biorefin. https://doi.org/10.1007/s13399-021-01666-9\u003c/li\u003e\n\u003cli\u003eLiu F, Wang X, Xu F, et al (2017) Fabrication and characterization of composites comprising (CHA)SAPO-34 with (MFI)ZSM-5 topologies and their catalytic performances on MTO reaction. Microporous and Mesoporous Materials 252:197\u0026ndash;206. https://doi.org/10.1016/j.micromeso.2016.02.024\u003c/li\u003e\n\u003cli\u003eLiu G, Tian P, Li J, et al (2008) Synthesis, characterization and catalytic properties of SAPO-34 synthesized using diethylamine as a template. Microporous and Mesoporous Materials 111:143\u0026ndash;149. https://doi.org/10.1016/j.micromeso.2007.07.023\u003c/li\u003e\n\u003cli\u003eMinova IB, Barrow NS, Sauerwein AC, et al (2021) Silicon redistribution, acid site loss and the formation of a core\u0026ndash;shell texture upon steaming SAPO-34 and their impact on catalytic performance in the Methanol-to-Olefins (MTO) reaction. J Catal 395:425\u0026ndash;444. https://doi.org/10.1016/j.jcat.2021.01.012\u003c/li\u003e\n\u003cli\u003eMohammadrezaei A, Papari S, Asadi M, et al (2012) Methanol to propylene: The effect of iridium and iron incorporation on the HZSM-5 catalyst. Front Chem Sci Eng 6:253\u0026ndash;258. https://doi.org/10.1007/s11705-012-0902-4\u003c/li\u003e\n\u003cli\u003eNumpilai T, Kahadit S, Witoon T, et al (2021) CO2 Hydrogenation to Light Olefins Over In2O3/SAPO-34 and Fe-Co/K-Al2O3 Composite Catalyst. Top Catal 64:316\u0026ndash;327. https://doi.org/10.1007/s11244-021-01412-5\u003c/li\u003e\n\u003cli\u003eOlsbye U, Svelle S, Bjrgen M, et al (2012) Conversion of methanol to hydrocarbons: How zeolite cavity and pore size controls product selectivity. Angewandte Chemie - International Edition 51:5810\u0026ndash;5831\u003c/li\u003e\n\u003cli\u003eOwgi AHK, Jalil AA, Aziz MAA, et al (2023) Methane dry reforming on fibrous silica-alumina employing nanocrystals of nickel and cobalt to recognize the most efficient metal. Int J Hydrogen Energy. https://doi.org/10.1016/j.ijhydene.2023.05.004\u003c/li\u003e\n\u003cli\u003ePolshettiwar V, Cha D, Zhang X, Basset JM (2010) High-surface-area silica nanospheres (KCC-1) with a fibrous morphology. Angewandte Chemie - International Edition 49:9652\u0026ndash;9656. https://doi.org/10.1002/anie.201003451\u003c/li\u003e\n\u003cli\u003eQureshi ZS, Jaseer EA (2020) Effective and selective direct aminoformylation of nitroarenes utilizing palladium nanoparticles assisted by fibrous-structured silica nanospheres. Research on Chemical Intermediates 46:4279\u0026ndash;4295. https://doi.org/10.1007/s11164-020-04206-8\u003c/li\u003e\n\u003cli\u003eRahman AFA, Jalil AA, Hamid MYS, et al (2022) Improved ethylbenzene suppression and coke-resistance on benzene methylation over metals doped fibrous silica-HZSM-5 zeolite. Molecular Catalysis 526:. https://doi.org/10.1016/j.mcat.2022.112370\u003c/li\u003e\n\u003cli\u003eRen S, Liu G, Wu X, et al (2017) Enhanced MTO performance over acid treated hierarchical SAPO-34. Cuihua Xuebao/Chinese Journal of Catalysis 38:123\u0026ndash;130. https://doi.org/10.1016/S1872-2067(16)62557-3\u003c/li\u003e\n\u003cli\u003eRen T, Patel M, Blok K (2006) Olefins from conventional and heavy feedstocks: Energy use in steam cracking and alternative processes. Energy 31:425\u0026ndash;451. https://doi.org/10.1016/j.energy.2005.04.001\u003c/li\u003e\n\u003cli\u003eSadrameli SM (2016) Thermal/catalytic cracking of liquid hydrocarbons for the production of olefins: A state-of-the-art review II: Catalytic cracking review. Fuel 173:285\u0026ndash;297\u003c/li\u003e\n\u003cli\u003eSimakov DSA, Wright MM, Ahmed S, et al (2015) Solar thermal catalytic reforming of natural gas: A review on chemistry, catalysis and system design. Catal Sci Technol 5:1991\u0026ndash;2016. https://doi.org/10.1039/c4cy01333f\u003c/li\u003e\n\u003cli\u003eSoheili S, Nakhaei Pour A, Mohammadi A (2021) SAPO-34 synthesis by combinations of structure-directing agents: Experimental and Monte Carlo simulations studies. Microporous and Mesoporous Materials 317:. https://doi.org/10.1016/j.micromeso.2021.111003\u003c/li\u003e\n\u003cli\u003eSoltanali S, Darian JT (2019) Synthesis of mesoporous SAPO-34 catalysts in the presence of MWCNT, CNF, and GO as hard templates in MTO process. Powder Technol 355:127\u0026ndash;134. https://doi.org/10.1016/j.powtec.2019.07.008\u003c/li\u003e\n\u003cli\u003eSt\u0026ouml; M (1999) Methanol-to-hydrocarbons: catalytic materials and their behavior1\u003c/li\u003e\n\u003cli\u003eSun C, Wang Y, Zhao A, et al (2020) Synthesis of nano-sized SAPO-34 with morpholine-treated micrometer-seeds and their catalytic performance in methanol-to-olefin reactions. Appl Catal A Gen 589:. https://doi.org/10.1016/j.apcata.2019.117314\u003c/li\u003e\n\u003cli\u003eSun Q, Wang N, Guo G, et al (2015) Synthesis of tri-level hierarchical SAPO-34 zeolite with intracrystalline micro-meso-macroporosity showing superior MTO performance. J Mater Chem A Mater 3:19783\u0026ndash;19789. https://doi.org/10.1039/c5ta04642d\u003c/li\u003e\n\u003cli\u003eSun Q, Wang N, Xi D, et al (2014) Organosilane surfactant-directed synthesis of hierarchical porous SAPO-34 catalysts with excellent MTO performance. Chemical Communications 50:6502\u0026ndash;6505. https://doi.org/10.1039/c4cc02050b\u003c/li\u003e\n\u003cli\u003eSun Q, Xie Z, Yu J (2018) The state-of-the-art synthetic strategies for SAPO-34 zeolite catalysts in methanol-to-olefin conversion. Natl Sci Rev 5:542\u0026ndash;558\u003c/li\u003e\n\u003cli\u003eTeh LP, Triwahyono S, Jalil AA, et al (2016) Fibrous silica mesoporous ZSM-5 for carbon monoxide methanation. Appl Catal A Gen 523:200\u0026ndash;208. https://doi.org/10.1016/j.apcata.2016.05.031\u003c/li\u003e\n\u003cli\u003eValecillos J, Epelde E, Albo J, et al (2020) Slowing down the deactivation of H-ZSM-5 zeolite catalyst in the methanol-to-olefin (MTO) reaction by P or Zn modifications. Catal Today 348:243\u0026ndash;256. https://doi.org/10.1016/j.cattod.2019.07.059\u003c/li\u003e\n\u003cli\u003eVarzaneh AZ, Towfighi J, Mohamadalizadeh A (2014) Comparative study of naphtha cracking over SAPO-34 and HZSM-5: Effects of cerium and zirconium on the catalytic performance. J Anal Appl Pyrolysis 107:165\u0026ndash;173. https://doi.org/10.1016/j.jaap.2014.02.017\u003c/li\u003e\n\u003cli\u003eVarzaneh AZ, Towfighi J, Sahebdelfar S (2016) Carbon nanotube templated synthesis of metal containing hierarchical SAPO-34 catalysts: Impact of the preparation method and metal avidities in the MTO reaction. Microporous and Mesoporous Materials 236:1\u0026ndash;12. https://doi.org/10.1016/j.micromeso.2016.08.027\u003c/li\u003e\n\u003cli\u003eWang P, Yang D, Hu J, et al (2013) Synthesis of SAPO-34 with small and tunable crystallite size by two-step hydrothermal crystallization and its catalytic performance for MTO reaction. In: Catalysis Today\u003c/li\u003e\n\u003cli\u003eWang Q, Wang X, Dai W, et al (2023) Core-shell SAPO-34@ZSM-5 composite via in situ solid-solid transformation of pre-coating MCM-41 shell and its application in methanol-to-olefins. Microporous and Mesoporous Materials 353:. https://doi.org/10.1016/j.micromeso.2023.112498\u003c/li\u003e\n\u003cli\u003eWu L, Hensen EJM (2014) Comparison of mesoporous SSZ-13 and SAPO-34 zeolite catalysts for the methanol-to-olefins reaction. Catal Today 235:160\u0026ndash;168. https://doi.org/10.1016/j.cattod.2014.02.057\u003c/li\u003e\n\u003cli\u003eWu W, Guo W, Xiao W, Luo M (2011) Dominant reaction pathway for methanol conversion to propene over high silicon H-ZSM-5. Chem Eng Sci 66:4722\u0026ndash;4732. https://doi.org/10.1016/j.ces.2011.06.036\u003c/li\u003e\n\u003cli\u003eYang Y, Sun C, Du J, et al (2012) The synthesis of endurable B-Al-ZSM-5 catalysts with tunable acidity for methanol to propylene reaction. Catal Commun 24:44\u0026ndash;47. https://doi.org/10.1016/j.catcom.2012.03.013\u003c/li\u003e\n\u003cli\u003eYaripour F, Shariatinia Z, Sahebdelfar S, Irandoukht A (2015) Effect of boron incorporation on the structure, products selectivities and lifetime of H-ZSM-5 nanocatalyst designed for application in methanol-to-olefins (MTO) reaction. Microporous and Mesoporous Materials 203:41\u0026ndash;53. https://doi.org/10.1016/j.micromeso.2014.10.024\u003c/li\u003e\n\u003cli\u003eZapater D, Lasobras J, Soler J, et al (2021) MTO with SAPO-34 in a Fixed-Bed Reactor: Deactivation Profiles. Ind Eng Chem Res 60:16162\u0026ndash;16170. https://doi.org/10.1021/acs.iecr.1c02718\u003c/li\u003e\n\u003cli\u003eZhang J, Xu L, Zhang Y, et al (2018) Hydrogen transfer versus olefins methylation: On the formation trend of propene in the methanol-to-hydrocarbons reaction over Beta zeolites. J Catal 368:248\u0026ndash;260. https://doi.org/10.1016/j.jcat.2018.10.015\u003c/li\u003e\n\u003cli\u003eZhang L, Wang H, Liu G, et al (2016) Methanol-to-olefin conversion over H-MCM-22 catalyst. J Mol Catal A Chem 411:311\u0026ndash;316. https://doi.org/10.1016/j.molcata.2015.11.013\u003c/li\u003e\n\u003cli\u003eZhang W, Fan S, Zhang J, et al (2019) Transformation of LPG on HZSM-5 catalyst: Effects of tuned pores and acidity on product distribution. Fuel 254:. https://doi.org/10.1016/j.fuel.2019.06.023\u003c/li\u003e\n\u003cli\u003eZheng T, Liu H, He P, et al (2022) Post synthesis of hierarchical SAPO-34 via citric acid etching: Mechanism of selective desilication. Microporous and Mesoporous Materials 335:. https://doi.org/10.1016/j.micromeso.2022.111798\u003c/li\u003e\n\u003cli\u003eZhou J, Zhang J, Zhi Y, et al (2018) Partial Regeneration of the Spent SAPO-34 Catalyst in the Methanol-to-Olefins Process via Steam Gasification. Ind Eng Chem Res 57:17338\u0026ndash;17347. https://doi.org/10.1021/acs.iecr.8b04181\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"environmental-chemistry-letters","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ecle","sideBox":"Learn more about [Environmental Chemistry Letters](https://www.springer.com/journal/10311)","snPcode":"10311","submissionUrl":"https://submission.nature.com/new-submission/10311/3","title":"Environmental Chemistry Letters","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Methanol-to-olefins, Fibrous Silica, Zeolite catalyst, SAPO-34, Olefin production, Porous materials","lastPublishedDoi":"10.21203/rs.3.rs-4631428/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4631428/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eGrowing concerns regarding the depletion of petroleum reserves and energy demand necessitate the exploration of alternative methods, such as methanol-to-olefin (MTO), to generate light olefins from non-crude oil sources. However, the industrial application of this method is limited due to the rapid deactivation of the catalyst, which is caused by the microporosity of the commercial catalyst. Here, we synthesized the fibrous silica-wrapped silico-alumino-phosphate (FSAPO-34) using a microemulsion technique with a seed-assisted synthesis method and applied it for the first time in the MTO reaction. The physicochemical properties of the fresh and spent catalysts were characterized by X-ray diffractometer, Fourier transform infrared spectroscopy-potassium bromide, N\u003csub\u003e2\u003c/sub\u003e physisorption, field emission scanning electron microscopy, transmission electron microscopy, NH\u003csub\u003e3\u003c/sub\u003e temperature-programmed desorption, thermal gravimetric analysis, O\u003csub\u003e2\u003c/sub\u003e temperature-programmed oxidation, and Raman spectroscopy. The findings indicated that the formation of fibrous silica on the surface of SAPO-34 exhibited a unique spherical morphology with dendrimeric silica fiber, significantly enhancing the mesoporosity from 0.098 to 1.749 cm\u0026sup3;/g compared to commercial microporous SAPO-34. FSAPO-34 demonstrates a significant improvement in catalytic lifetime, with a 54% increase, from 19.2 hours to 29.5 hours, compared to commercial SAPO-34. This enhanced stability is attributed to the introduction of mesoporosity in FSAPO-34, which, in turn, provides high accessibility and reduced diffusion resistance of products and ultimately retarded the formation of coke.\u003c/p\u003e","manuscriptTitle":"Enhanced coke resistance in methanol to olefins reaction via surplus mesoporosity of fibrous silica-wrapped SAPO-34","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-09 16:57:15","doi":"10.21203/rs.3.rs-4631428/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2024-07-12T10:58:13+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-08T14:26:44+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-06-25T14:18:58+00:00","index":"","fulltext":""},{"type":"submitted","content":"Environmental Chemistry Letters","date":"2024-06-24T12:13:39+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"environmental-chemistry-letters","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ecle","sideBox":"Learn more about [Environmental Chemistry Letters](https://www.springer.com/journal/10311)","snPcode":"10311","submissionUrl":"https://submission.nature.com/new-submission/10311/3","title":"Environmental Chemistry Letters","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"46c38e4c-5778-4cc9-bf88-a6227c5b090c","owner":[],"postedDate":"August 9th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-05-26T16:07:05+00:00","versionOfRecord":{"articleIdentity":"rs-4631428","link":"https://doi.org/10.1007/s10311-025-01845-4","journal":{"identity":"environmental-chemistry-letters","isVorOnly":false,"title":"Environmental Chemistry Letters"},"publishedOn":"2025-05-21 15:58:05","publishedOnDateReadable":"May 21st, 2025"},"versionCreatedAt":"2024-08-09 16:57:15","video":"","vorDoi":"10.1007/s10311-025-01845-4","vorDoiUrl":"https://doi.org/10.1007/s10311-025-01845-4","workflowStages":[]},"version":"v1","identity":"rs-4631428","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4631428","identity":"rs-4631428","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}