Optimization of Operational Parameters for Improved Light Olefin Production in Gasoil Cracking over HZSM-5 Catalyst: Temperature and Catalyst Loading Weight as Key Parameters

Optimization of Operational Parameters for Improved Light Olefin Production in Gasoil Cracking over HZSM-5 Catalyst: Temperature and Catalyst Loading Weight as Key Parameters | 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 Optimization of Operational Parameters for Improved Light Olefin Production in Gasoil Cracking over HZSM-5 Catalyst: Temperature and Catalyst Loading Weight as Key Parameters Naemeh Yasrebi, Jafarsadegh Moghaddas This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7402064/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This study investigates the catalytic cracking of gasoil over HZSM-5 zeolite with an emphasis on gasoil conversion and light olefin selectivity as a function of reaction conditions. For this purpose, the NaZSM-5 zeolite was ion-exchanged to make its protonated form. Then the resulting catalyst was used to evaluate the conversion, selectivity, and propylene/ethylene ratio in reactions carried out at 500, 550, and 600 °C temperatures with catalyst loading weights of 0.1, 0.3, and 0.5 gr. Both propylene and ethylene selectivity were enhanced by temperature across all catalyst weights, with the propylene enhancement being somewhat milder and a decreasing trend observed in the propylene-to-ethylene ratio. Catalyst weight dominated selectivity, with 0.3 gr producing the highest light olefins (53.57-58.78%), while 0.5 gr at 500 °C provided the lowest (30.55%), increasing secondary reactions. Conversion was maximum at 0.3 gr (87.47% at 600 °C), corresponding to light olefins formation. Catalytic cracking MFI zeolite ZSM-5 Light olefins Gasoil Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 1. INTRODUCTION The chemical industry depends considerably on light olefins- especially propylene and ethylene- as the necessary building blocks for the manufacturing of various chemicals and polyolefins [1–3] . Among them, ethylene appears to be the most in-demand light olefin on the global market, with an annual production of 155 million tons [4] . However, the ongoing increase in propylene products worldwide could potentially exceed ethylene in the market in the future [5] . The substantial rise in propylene consumption is primarily driven by the increasing demand for its main downstream product, polypropylene [6] . Currently, both ethylene and propylene are primarily produced as major by-products of naphtha steam cracking, a process that accounts for over 80% of total light olefins production. Light hydrocarbons, such as ethane, or light oils, such as naphtha and light cycle oil, are used as feedstock in this process. However, because of the increasing demand worldwide, there is a shortage of light oil supplies. Therefore, it is better to use heavier feedstock when making light olefins [7] . The type of feedstock used and the operating parameters have a significant effect on the product yield of steam cracking. Steam cracking, the most energy-intensive process in the petrochemical sector, produces much CO 2 and can reach reaction temperatures of up to 800°C [ 8 – 10 ]. Including a catalyst during hydrocarbon cracking reduces the temperature as well as decreasing CO 2 emission [ 11 ]. On the other hand, catalytic cracking provides significant flexibility and high propylene selectivity at around 500°C [ 12 ]. Fluid Catalytic Cracking (FCC) remains vital in today’s market due to its capability to produce valuable light olefins (ethylene, propylene, butenes) and aromatics from hydrocarbons [ 13 ]. In order to increase the production yield of particular products or prevent undesired side reactions, shape-selective catalysts such as zeolites is essential in catalytic cracking [ 14 , 15 ]. Among zeolites, ZSM-5 stands out due to its exceptional activity, hydrothermal stability, and resistance to carbon deposition [ 16 – 20 ]. The effect of ZSM-5 additives on the selectivity of FCC products has been the subject of numerous investigations [ 21 – 23 ]. In most cases it is reported that the ZSM-5 can improve the light olefins yields when used in FCC operation [ 24 – 26 ]. Because of its porous nature, ZSM-5 exhibits remarkable shape-selective catalytic activity [ 14 , 27 , 28 ]. Aside from its catalytic role, ZSM-5 can act as an effective sorbent because of its high surface area and microporous structure gives the ability to selectively adsorb and separate hydrocarbon species [ 29 – 31 ]. Additionally, its active Bronsted acid sites are identified as the active catalytic sites that account for the promotion of the cracking reaction [ 32 ]. The feed characteristics, operating environment, and catalysts all have a significant effect on the amount of FCC propylene. Operating parameters, particularly temperature, significantly influence the distribution of products [ 33 ]. Optimization of a process involves altering the process to maximize an identified number of parameters while maintaining a particular set of constraints. It is frequently employed to increase the production cost-efficiency, productivity and throughput [ 34 ]. Various studies have surveyed the conversion of naphtha [ 35 ], gasoil cracking, or other feedstock over ZSM-5 in order to increase the yield of light olefins by adjusting these factors [ 36 ]. Apart from assessing various feedstocks, scientists have also evaluated how important operational parameters—like reaction temperature, residence time, and weight hourly space velocity (WHSV)—affect product distribution. These parameters are essential in order to maximize the production of valuable light olefins like ethylene and propylene and optimize reaction pathways. Feng et al. studied how reaction temperature affects the catalytic cracking of naphtha over F/HZSM-5 reporting the yield of ethylene and propylene by temperature [ 37 ]. Lu et al.'s work on CrHZSM-5 zeolites highlights the importance of reaction temperature in enhancing light olefin yield in isobutane cracking [ 38 ]. Zhao et al. also found that temperature was a major variable determining light olefins selectivity in the catalytic cracking of gasoil [ 39 ]. Despite the fact that ZSM-5 has been thoroughly investigated in FCC and naphtha cracking, performance in gasoil cracking at different temperatures and catalyst loadings- particularly as a pure zeolite without combination with Y zeolite or metal loading- has not been explored. To fill this gap, the present work attempts to investigate the effects of reactor temperature and catalyst loading weight on feed conversion and light olefin selectivity during catalytic gasoil cracking over HZSM-5 catalyst. 2. EXPERIMENTAL 2.1. Catalyst preparation In this study, a commercial sample of Na-ZSM-5 zeolite having a SiO₂/Al₂O₃ molar ratio of 36 was used as the parent catalyst material. The catalyst was then ion-exchanged to get the proton form according to ref. [ 40 ]. For this purpose, 5 g of Na-ZSM-5 was added to 150 ml of 1 M ammonium nitrate solution and stirred for three hours on the heater at 80°C under the reflux. Then, the solution was filtered and washed with a specific volume of 80°C deionized water. The sample was subsequently dried at 110°C, and this procedure was repeated two more times. Finally, it was calcined for four hours at 550°C in static air to transform the NH 4 -ZSM-5 catalyst into HZSM-5. The resulting catalyst was shaped into cylindrical pellets (3 mm in diameter and 5 mm in height) using 3% bentonite as binder, followed by drying at 110°C for 12 hours. 2.2. Characterization XRD patterns were recorded on a PW1730 PHILIPS diffractometer with Cu Ka radiation at 40 kV and 30 mA, and a scanning rate of 1 sec. Textural properties of the samples were determined by nitrogen adsorption-desorption isotherms using the Belsorp mini II instrument (Japan). Before conducting the adsorption measurements, samples were degassed for two hours at 120°C. The specific surface areas of the samples were calculated based on the BET isothermal equation. Pore size distribution was calculated by using Barrett–Joyner–Halenda (BJH) method while micropore surface area, micropore volume and external surface area were evaluated using the t-plot method. The morphology of the samples was characterized using a MIRA/TESCAN scanning electron microscope. The silicon and aluminum contents in ZSM-5 were determined using X-ray fluorescence (XRF) analysis. Thermogravimetric analysis (TGA) was conducted on the spent catalysts using a STA6000 analyzer, with the temperature programmed from 40°C to 950°C under a nitrogen atmosphere at a constant heating rate of 10°C per minute. The gaseous products were analyzed using a gas chromatography (Agilent Technologies 7890A GC) equipped with HP-Plot/Q (30 m, 0.53 mm, 40 µm) capillary column and FID detector. 2.3. Experimental setup Gasoil from the Tabriz Oil Refinery was injected into a Pyrex round-bottom vessel at a regulated flow rate of 2.74 mL/h using a syringe pump (702 SM Titrino, Metrohm). The atmospheric gasoil used in this investigation had a density of 0.832 g/cm³ and a boiling range of 170°C to 361°C. Its detailed properties are listed in Table 1 . Nitrogen was employed as the carrier gas and introduced into the Pyrex round-bottom vessel at a controlled flow rate, regulated by a flowmeter. The tubular reactor (10 mm inner diameter) was heated using a programmable furnace. Under constant nitrogen flow, the furnace was ramped up to the target temperature for each experiment at a rate of 10°C/min, and it was maintained there for the predetermined time. An electric mantle was used to heat the Pyrex round-bottom vessel once the reactor temperature had stabilized. Gasoil was then injected upon the temperature had reached the desired level. The vessel was maintained within a temperature range of 360–362°C. The generated vapors flowed into the reactor and contacted the catalyst bed. To minimize heat loss, the vessel and associated connections were insulated with rock wool. The effluent from the reactor was quenched by one water-cooled condenser, followed by a decanter placed in an ice bath. After separating the products, the liquid products were collected, and the gas mixture was analyzed using the gas chromatography equipment. Figure 1 displays the schematic diagram of the experimental setup. Each experiment was carried out for two hours to measure conversion and selectivity at different temperatures and catalyst loading weights. Based on gas chromatography (GC) data, the molar selectivity was calculated as the ratio of the moles of a particular product formed to the total moles of all products. Each component's molar selectivity (mol%) was multiplied by its corresponding molecular weight to determine the weight percentage selectivity (wt.%). The gas and liquid yields were computed using the following formulas: Y liquid = (weight of liquid) / (weight of feed) * 100% Y gas = (weight of feed- weight of liquid) / (weight of feed) * 100% Table 1 properties of gasoil as feedstock Properties Value Density (gr/cm 3 ) 0.832 Viscosity (cSt) Total sulfur (ppm) Refractive Index (nD) Initial Boiling Point (°C) 05% 10% 20% 30% 40% 50% 60% 70% 80% 90% 95% Final Boiling Point (°C) 6.34 1 1.4555 170 182 189 201 217 235 250 273 286 306 330 349 361 3. RESULTS AND DISCUSSION 3.1. Catalyst characterization Figure 2 shows the XRD patterns of the ion-exchanged ZSM-5 (HZSM-5) zeolite samples, which feature sharp peaks at 2θ = 7–9° and 22–25°, characteristic of the MFI-type framework. These high crystallinity and phase purity peaks highlight no impurity peaks, so proving that the zeolite structure was maintained after the ion-exchange process [ 41 – 43 ]. Both samples display the distinctive hexagonal shape of ZSM-5 zeolite with particle sizes ranging from 1 to 3 µm (Fig. 3 ). The overall crystal morphology is essentially unchanged following ion exchange, suggesting that the zeolite's structural integrity was maintained. The surfaces of the HZSM-5 crystals stay smooth and show no signs of collapse or cracking, and they seem somewhat more compact. There is no discernible agglomeration or sintering, indicating that the particle morphology and crystallinity were not negatively impacted by the ion-exchange treatment. The nitrogen adsorption–desorption isotherm of HZSM-5 (Fig. 4 ) is in accordance with the IUPAC Type IV classification, which is generally connected to mesoporous materials. The sample has a wide range of pores with different sizes. The sample contains pores with varying sizes across a broad spectrum. A summary of the physicochemical properties of the HZSM-5 catalyst, including its textural and structural properties that influence its catalytic performance in gasoil cracking, is given in Table 2 . XRF analysis revealed a slight decrease in the SiO 2 /Al 2 O 3 ratio compared to the purchased commercial Na- ZSM-5, following the ion exchange process, suggesting that limited silicon was removed from the zeolite framework. It also indicates an intermediate acidic level, which maintains the acid density needed in cracking reactions and suppresses unwanted coke formation. Table 2 Textural properties of HZSM-5 catalyst catalyst SiO 2 /Al 2 O 3 molar ratio BET surface area (m 2 /gr) Total pore volume (cm 3 /gr) Average pore diameter (nm) HZSM-5 33 45.60 0.052 4.56 Thermogravimetric analysis was employed to compare the extent of coke formation on three spent catalysts that were operated at different temperatures with the catalyst loading weight of 0.3 gr: 500°C, 550°C, and 600°C. The weight loss (Fig. 5 ) from coke burning, calculated based on the initial and residual weights, was 8.87%, 9.72%, and 9.25% for the 500°C, 550°C, and 600°C treated catalyst, respectively. Normalized to the initial sample weights of 21.869 mg, 24.284 mg, and 18.220 mg, the real amounts of coke were determined to be approximately 1.94 mg, 2.36 mg, and 1.69 mg, respectively. The maximum coke deposition at 550 ° C indicates that this temperature can favor secondary reactions toward the formation of additional coke. However, at 600°C, the coke content is the lowest, which could be explained by increased gas-phase cracking and coke gasification processes that suppress coke accumulation. This interpretation suggests that the reaction temperature strongly influences the degree of catalyst deactivation through coke formation. 3.2. Catalytic results 3.2.1. Impact of process variables Initial identification of critical process parameters is necessary for effective optimization. Based on the prior experiences, we took into account the following process variables with catalytic cracking: (i) reactor temperature; (ii) catalyst loading weight. These parameters were varied between 500 and 600°C (a typical operating range for gasoil cracking over zeolite catalysts), and 0.1 and 0.5 g, respectively and the experiments were repeated twice [ 3 ]. The effect of the mentioned variables on gasoil conversion, ethylene selectivity, propylene selectivity, and total selectivity of ethylene and propylene were investigated. Table 2 displays the obtained experimental values where the results are the average values from the two independent measurements conducted under identical conditions. Table 3 data for catalytic cracking of gasoil over HZSM-5 catalyst at different temperatures and catalyst loading weights Test order Temperature (°C) Catalyst loading weight (gr) Ethylene selectivity (wt. %) Propylene selectivity (wt. %) Ethylene + Propyelen selectivity (wt %) Propylene/Ethylene Conv (1hr) 1 500 0.1 10.06 33.39 43.45 3.32 81.01 2 550 0.1 13.39 36.61 50.00 2.73 77.76 3 600 0.1 15.27 39.10 54.37 2.56 81.29 4 500 0.3 11.11 32.33 53.57 2.91 87.40 5 550 0.3 14.48 36.13 58. 78 2.70 84.00 6 600 0.3 18.03 37.88 58.34 2.10 87.47 7 500 0.5 9.31 31.87 30.55 3.42 81.0 8 550 0.5 15.13 38.89 40.25 2.57 81.31 9 600 0.5 19.50 41.16 45.22 2.11 87.34 Figure 6 (a) represents the relationship of gasoil conversion (wt.%) versus reaction temperature under varying catalyst loading weights. Catalytic cracking of gasoil within a temperature range of 500 to 600°C displays distinctive patterns of conversion depending on the catalyst loading weights. For the smallest catalyst loading weight (0.1 gr), conversion is a U-shaped function of temperature with a steep fall at 550°C. This decrease is probably the result of deficiency in active sites and the start of coke formation, which is common in cracking of gasoil over zeolites which partially deactivates the catalyst. For an intermediate catalyst loading weight of 0.3 gr, the minimum conversion occurs at 550°C because there is maximum coke formation. This result is consistent with the literature that coke formation at medium temperatures is likely to cause the pore blockage in the catalyst and hence coverage of active sites, thereby reduced catalytic activity. Coke, formed from polyaromatic intermediates, can deposit on the external surface or within the mesopores of the cylindrical pellets, blocking access to active sites. The HZSM-5 used in this study, with a mesoporous structure (~ 4.6 nm), will be expected to minimize the severe pore blockage compared to traditional microporous ZSM-5 (~ 0.5–0.6 nm). At 600°C, there is a moderate loss in coke content correlated with conversion recovery, presumably due to partial coke gasification or enhanced coke resistance at elevated temperatures, both of which enhance active site availability. Alternatively, the highest loading of the catalyst (0.5 g) shows a smooth increase in conversion with temperature. This agrees with previous studies confirming that higher C/O ratios can help reduce coke- related catalyst deactivation by the presence of surplus active sites and coke dispersion or burn-off. As shown in Fig. 6 (b), the amount of catalyst affects the conversion at different reaction temperatures. The highest conversion occurs at 0.3 g for both 500°C and 550°C. Despite the observed conversion trends across the temperature range, statistical analysis verified that temperature did not have a significant effect on conversion between 500°C and 600°C but the catalyst loading weight exerted a more dominant influence on conversion under the conditions studied. To obtain a better understanding of the product distribution, the impact of temperature and catalyst loading weight on product selectivity were examined. Figure 7 (a) shows the selectivity of ethylene versus temperature. The selectivity graph of ethylene illustrates a monotonic increase with temperature, indicating that thermal cracking predominates as the primary mechanism for ethylene formation [ 37 , 38 ]. Furthermore, the 0.5 gr catalyst exhibits the most pronounced rate of temperature-induced increase in ethylene selectivity, suggesting that temperature and catalyst loading weight synergistically promote the formation of ethylene. Under the thermal cracking process and findings from the literature, higher catalyst-to-oil ratios result in higher light olefin yields because they have more active sites and better control over secondary reactions. Temperature and catalyst loading weight also increase ethylene selectivity. In line with these conclusions, Zhao et al. discovered that an increase in ZSM-5 leads to a linear increase in ethylene production in addition to a notable increase in propylene and butene yields [ 39 ]. Figure 8 shows the propylene selectivity graph. Since propylene is an intermediate species, moderate reaction conditions yield the highest yield. Propylene selectivity increased steadily with temperature across all catalyst loading weights, reaching a maximum of 600°C. According to reports in the literature, propylene formation typically peaks between 550°C and 600°C, which is consistent with this pattern. Since propylene is an intermediate species, its maximum yield occurs under mild reaction conditions. After that, selectivity may decline due to increased secondary cracking and hydrogen transfer reactions that convert light olefins into lighter gases or saturated hydrocarbons [ 44 , 45 ]. Even though higher temperatures were not examined in this work, the observed maximum at 600°C suggests that this temperature may be close to the optimal conditions for maximizing propylene yield under the given circumstances. According to the data, ethylene selectivity rises as catalyst loading weight does. This trend differs in the case of propylene, where the selectivity remains relatively constant, showing only minor fluctuations. This implies that propylene formation is less sensitive to the number of acid sites. Propylene always had the highest selectivity among the gas-phase products at all temperatures [ 33 ], resulting in propylene-to-ethylene (P/E) ratios above two under all experimental conditions. Higher selectivity toward propylene suggests that the HZSM-5 catalyst's structural and acidic properties favored the formation of C 3 olefins over C 2 . However, as the temperature increased, the P/E ratio showed a declining trend, indicating that high thermal energy favors the formation of ethylene over propylene. Similar findings were reported by Kubo et al. [ 43 ], who discovered that while the propylene-to-ethylene ratio decreased from 3 at 723 K to 1.4 at 923 K, higher ethylene and propylene selectivity was correlated with higher reaction temperatures. The variation of catalyst loading also had an impact on the P/E ratio; when the catalyst amount was raised from 0.1 to 0.3 gr, the P/E ratio dramatically dropped, indicating the improvement in ethylene yield generated by more active sites and increased cracking activity. Remarkably, a continued increase to 0.5 gr overturned this at the lower temperatures, perhaps due to diffusion limitation or coke deposition affecting ethylene selectivity. These results highlight the delicate balance between catalyst properties and reaction conditions in controlling product distribution in gasoil cracking. The sum of the individual selectivities of ethylene and propylene was used to determine their total selectivity. There is a noticeable correlation between reactor temperature and catalyst loading weight and the selectivity of total light olefins. The total light olefins graph (Fig. 9 ) shows that raising the temperature from 500°C to 600°C improves light olefin selectivity for all catalyst loading weights [ 18 , 42 ]. The highest overall selectivity is consistently achieved by 0.3 gr, peaking at about 59 wt.% at 550°C. A favorable thermal activation range for the synthesis of olefins is reflected in this behavior. The increase in the ratio of monomolecular cracking as opposed to traditional bimolecular cracking may be the primary cause of the selectivity shift with reaction temperature. Selectivity is somewhat reduced compared to 0.3 gr at higher catalyst loading weights (e.g., 0.5 gr), indicating that excessive catalyst loading may result in secondary reactions that lower olefin yield. The graphs for each product support these trends. Across all catalyst loading weights, ethylene selectivity increases steadily with temperature, peaking at roughly 20 wt. % at 600°C with 0.5 gr. This suggests that higher temperatures promote cracking pathways that favor the formation of ethylene. However, with selectivity values ranging from about 32 wt.% to about 42 wt.% propylene, dominates the light olefin distribution. Optimizing process conditions primarily increases propylene formation, while ethylene production plays a secondary but supportive role in the total olefin selectivities. It is reasonable to raise the reaction temperature in order to improve light olefin selectivity because the cracking reaction increases entropy [ 1 ]. At all temperatures, methane selectivity (Fig. 10 ) declines as catalyst weight increases; the maximum selectivity was observed at 500°C and 0.1 g. Increased catalyst weight reduces the selectivity of methane by increasing contact time and active surface area, which promotes further conversion of methane into other products like CO or CO₂. The objectives of the optimization study for gasoil catalytic cracking are to simultaneously maximize light olefins production and gasoil conversion along with the minimum coke formation [ 3 ]. Considering the results of temperature and catalyst loading weight variations, optimal conditions for subsequent experiments were established. We concluded that 500°C and 0.3 gr are the appropriate conditions due to their practical applications in industry. By operating the process at this particular temperature and catalyst quantity, coke formation is reduced, energy is saved, and a high conversion rate of 87% is achieved, ensuring stable reactor operation. According to the literature, the reactor temperature of 500°C is at the lower end of the typical range (500–550°C) for the production of light olefins over HZSM-5 [ 46 ]. In operations where stability or wider product distributions are more important, 500°C is sometimes used, even though 525–550°C is typically more characteristic of optimizing light olefin yield. As reported in the literature, the accumulation of coke on the catalyst's active sites contributes to a reduction in mass conversion [ 47 ]. With regard to this deactivation mechanism, it is crucial to investigate how catalyst performance changes over time under fixed operating conditions. Accordingly, the light olefins selectivity, i.e., ethylene and propylene, and the feed conversion have been studied at the operation time between 0 and 360 min at a constant temperature of 500°C and catalyst weight of 0.3 gr. Figure 11 illustrates how the selectivity of ethylene and propylene is comparatively constant over the course of the 6-hour reaction, with only slight variations noted between 10 and 12%. This suggests that these lighter olefins are consistently produced under the specified conditions. The minor changes in ethylene and propylene selectivity also indicate that the catalyst was relatively stable during the whole period of time, as there have been no major deactivations nor changes in product distribution. In times where the selectivity is higher than that during the first hour, it may just be the result of temperature variations and heating vessel variable operations. The stability of ethylene and propylene selectivity over time is very similar to results in the literature of catalytic cracking of gasoil using HZSM-5 catalyst. The ZSM-5 zeolite has highly acidic, strongly shape selective, and thermally stable properties, which are incredibly beneficial for the continuous production of light olefins in the reaction condition. Numerous studies demonstrate that propylene selectivity remains high and stable over long reaction times when ZSM-5 is utilized as the main cracking catalyst or as an additive. For instance, a study by Corma et al. demonstrated that even when operational severity varies, the addition of ZSM-5 to fluid catalytic cracking (FCC) systems maintains propylene selectivity while increasing light olefin yields. Furthermore, hierarchical or nanoscale ZSM-5 structures have been shown to optimize ethylene formation while decreasing deactivation due to diffusion limitations and coke deposition [ 3 ]. The gas oil conversion pattern (Fig. 12 ) over the ZSM-5 catalyst at 500°C and 0.3 gr catalyst loading weight showed an abrupt fall with time, from 70% at 60 minutes to 35% at 360 minutes. This suggests that the catalyst has been deactivated by coke deposited on the active acid sites. The initial sharp drop is typical of rapid coke formation followed by a less rapid deactivation stage as pore plugging and site poisoning still goes on. Similar phenomena have been documented in the literature. One article on the usage of HZSM-5 catalysts for the cracking of n-hexane mentioned coke deactivation after long-term operations, thus revealing the impact of coke on catalyst performance. 4. CONCLUSION This experiment has researched the impact of reaction temperature and catalyst loading weight on gasoil conversion and light olefins production during catalytic cracking. The reaction temperature was found to be a significant factor. The conversion of gasoil reached a minimum at 550°C for catalyst weights of 0.1 and 0.3 gr, stated by experimental results. This was supported by the conception of the coke and the lack of acid sites that were not sufficient to continue the cracking reaction. A 0.5 g catalyst weight, on the other hand, showed a typical increasing conversion trend with temperature, most likely as a result of improved resistance to deactivation and increased active site availability. For all catalyst weights, the selectivity of light olefins, particularly ethylene and propylene, increased steadily with temperature, suggesting that higher temperatures favor the production of light olefins. Also, the conversion of gasoil was influenced by catalyst weight; the highest conversion was obtained with a catalyst loading weight of 0.3 gr. This is the indication of the ideal ratio of the combination of the acid sites that are present and the coke that is diminished. The total selectivity for light olefins also increased when the catalyst weight was raised, indicating that the active sites facilitate the formation of the targeted light olefins. The temperature of 500°C and a catalyst weight of 0.3 gr were selected as the best working conditions for further experiments. This option guarantees stable and efficient performance of the reactor by reducing coke formation, saving energy, and attaining a high conversion rate of 87%. 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Harding, The dependence of ZSM-5 additive performance on the hydrogen-transfer activity of the REUSY base catalyst in fluid catalytic cracking. Appl. Catal. A: General. 214(2001) 11-29. https://doi.org/10.1016/S0926-860X(01)00482-3 Arandes, J.M., et al., HZSM-5 zeolite as catalyst additive for residue cracking under FCC conditions. Energy Fuels. 23(2009) 4215-4223. https://doi.org/10.1021/ef9002632 Buchanan, J., D. Olson, and S. Schramm, Gasoline selective ZSM-5 FCC additives: effects of crystal size, SiO 2 /Al 2 O 3 , steaming, and other treatments on ZSM-5 diffusivity and selectivity in cracking of hexene/octene feed. Appl. Catal. A: General,. 220 (2001) 223-234. https://doi.org/10.1016/S0926-860X(01)00712-8 Corma, A., et al., Different process schemes for converting light straight run and fluid catalytic cracking naphthas in a FCC unit for maximum propylene production. Appl. Catal. A: General,. 265(2004) 195-206. https://doi.org/10.1016/j.apcata.2004.01.020 Bortnovsky, O., P. Sazama, and B. Wichterlova, Cracking of pentenes to C 2 –C 4 light olefins over zeolites and zeotypes: Role of topology and acid site strength and concentration. Appl. Catal. A: General, 2005. 287(2): p. 203-213.https://doi.org/10.1016/j.apcata.2005.03.037 Jung, J.S., J.W. Park, and G. Seo, Catalytic cracking of n-octane over alkali-treated MFI zeolites. Appl. Catal. A: General,. 288(2005) 149-157. https://doi.org/10.1016/j.apcata.2005.03.037 Liu, H., et al., Hierarchical ZSM-5 nanosheets for production of light olefins and aromatics by catalytic cracking of oleic acid. Sustainable Energy & Fuels,. 9(2025) 152-171. 10.1039/D4SE01167H Abedpour, H., J. Moghaddas, and R. Alizadeh, Adsorption of lead from aqueous solution using nanostructured silica aerogel/zeolite ZSM-5 composite. Iranian Chemical Engineering Journal, 2023. 22: p. 7-32. Abedpour, H., et al., Experimental study and machine learning simulation of Pb (II) separation from aqueous solutions via a nanocomposite adsorbent. J. Taiwan Inst. Chem. Eng, 2023. 147: p. 104923. https://doi.org/10.1016/j.jtice.2023.104923 Zhao, W., et al., The design of core–shell ZSM-5@ NiAl-LDH composites for efficient adsorption of VOCs under high humidity. Sep. Purif. Technol., 2025. 355: p. 129729. https://doi.org/10.1016/j.seppur.2024.129729 Schallmoser, S., et al., Impact of the local environment of Brønsted acid sites in ZSM-5 on the catalytic activity in n-pentane cracking. J. Catal. 316 (2014) 93-102. https://doi.org/10.1016/j.jcat.2014.05.004 Tarighi, S. and A. Afshar Ebrahimi, Physical mixture of MCM-41/ZSM-5 as an active catalyst component for maximization of propylene in Catalytic cracking of VGO. Pet. Sci. Technol., 35(2017): p. 2158-2163. https://doi.org/10.1080/10916466.2017.1389959 Zakria, M.H., et al., Propylene Yield Assessment utilizing Response Surface Methodology for Naphtha Pyrolysis Cracking. (2023) Momayez, F., J.T. Darian, and S.M.T. Sendesi, Synthesis of zirconium and cerium over HZSM-5 catalysts for light olefins production from naphtha. J. Anal. Appl. Pyrolysis. 112 (2015) 135-140. https://doi.org/10.1016/j.jaap.2015.02.006 Shao, Q., et al., Study of the application of structural catalyst in naphtha cracking process for propylene production. Catal. Today. 147 (2009) S347-S351. https://doi.org/10.1016/j.cattod.2009.07.056 Feng, X., et al., Highly effective F-modified HZSM-5 catalysts for the cracking of naphtha to produce light olefins. Energy Fuels, 24(2010) 4111-4115. https://doi.org/10.1021/ef100392d Lu, J., et al., CrHZSM-5 zeolites–Highly efficient catalysts for catalytic cracking of isobutane to produce light olefins. Catal Lett ,. 109 (2006) 65-70. https://doi.org/10.1007/s10562-006-0058-2 Zhao, X. and T.G. Roberie, ZSM-5 additive in fluid catalytic cracking. 1. Effect of additive level and temperature on light olefins and gasoline olefins. Ind. Eng. Chem. Res. 38(1999) 3847-3853. https://doi.org/10.1021/ie990179q Safari, S., M. Ebrahimynejad, and R. Karimzadeh, Vacuum residue upgrading by pyrolysis-catalysis procedure over mesoporous ZSM-5 zeolite. Journal of Oil, Gas and Petrochemical Technology, 6(2019) 51-62. 10.22034/JOGPT.2019.101419 Li, X., B. Shen, and C. Xu, Interaction of titanium and iron oxide with ZSM-5 to tune the catalytic cracking of hydrocarbons. Appl. Catal. A: General,. 375(2010) 222-229. https://doi.org/10.1016/j.apcata.2009.12.033 Hou, X., et al., Promotion on light olefins production through modulating the reaction pathways for n-pentane catalytic cracking over ZSM-5 based catalysts. Appl. Catal. A: General, 543 (2017) 51-60. https://doi.org/10.1016/j.apcata.2017.06.013 Kubo, K., et al., Selective formation of light olefin by n-heptane cracking over HZSM-5 at high temperatures. Microporous Mesoporous Mater., 149(2012) 126-133. https://doi.org/10.1016/j.micromeso.2011.08.021 Jiang, G., et al., Highly effective P-modified HZSM-5 catalyst for the cracking of C4 alkanes to produce light olefins. Appl. Catal. A: General, 340(2008) 176-182. https://doi.org/10.1016/j.apcata.2008.02.011 Song, Z., et al., Production of propylene from ethanol over ZSM-5 zeolites. Catal Lett,. 131 (2009) 364-369. https://doi.org/10.1007/s10562-009-0071-3 Al-Khattaf, S., et al., Diffusion and catalytic cracking of 1, 3, 5 tri-iso-propyl-benzene in FCC catalysts. Chem. Eng. Sci., 57(2002) 4909-4920. https://doi.org/10.1016/S0009-2509(02)00277-4 Liu, Q., et al., The performance of catalytic conversion of ZSM-5 comodified with gold and lanthanum for increasing propylene production. Ind. Eng. Chem. Res., 58(2019) 14695-14704. https://doi.org/10.1021/acs.iecr.9b02612 Cite Share Download PDF Status: Posted Version 1 posted 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-7402064","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":503827889,"identity":"4b9b15c0-c854-4d05-bba2-43e42dfc7520","order_by":0,"name":"Naemeh Yasrebi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA00lEQVRIiWNgGAWjYBCDBDb2BiiTmWgtPAcYGA6QpIVBIgGqhRAwZ+Ax/Phzj00en+TzZ9IfGOzkGdh5H+DVYtnAYyzN8yytmE06x0ziAEOyYQMzuwFeLQYHeAykGQ4cTmyTzmEDamFOYGBmw+8woBbjnz8O/E9skzz+DKilnigtZhI8Bw4ktkkwgBx2mBgtbGXWPAeSi9l4cowtzhgcN2wjrIV5880fB+zy5NuPP7xRUVEtz89/DL8WBvkXyOEDZBOwAwTYHxBWMwpGwSgYBSMbAACJADq2cFyy1wAAAABJRU5ErkJggg==","orcid":"","institution":"Tabriz University of Technology: Sahand University of Technology","correspondingAuthor":true,"prefix":"","firstName":"Naemeh","middleName":"","lastName":"Yasrebi","suffix":""},{"id":503827890,"identity":"33f413be-d3ce-448d-8fe7-1f89b8fed6c8","order_by":1,"name":"Jafarsadegh Moghaddas","email":"","orcid":"","institution":"Tabriz University of Technology: Sahand University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Jafarsadegh","middleName":"","lastName":"Moghaddas","suffix":""}],"badges":[],"createdAt":"2025-08-18 17:49:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7402064/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7402064/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":90308988,"identity":"3154d0e0-02a9-4c49-9d99-b4d6650224cf","added_by":"auto","created_at":"2025-09-01 09:38:23","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":80780,"visible":true,"origin":"","legend":"\u003cp\u003eschematic diagram for continuous setup of catalytic cracking of gas oil\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7402064/v1/72f28dcd0d5cc0d47ec0f2b2.png"},{"id":90308968,"identity":"d2d0fed6-019f-47ee-a8b2-bc7ec6895b15","added_by":"auto","created_at":"2025-09-01 09:38:21","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":9064,"visible":true,"origin":"","legend":"\u003cp\u003eXRD pattern of HZSM-5 catalyst\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7402064/v1/704aa45d4a6b2dc8a15f3abb.png"},{"id":90308986,"identity":"a69ee12f-9b3d-4da1-8ff4-974d6958de78","added_by":"auto","created_at":"2025-09-01 09:38:22","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":163679,"visible":true,"origin":"","legend":"\u003cp\u003eFE-SEM image of the (a) NaZSM-5 and (b) HZSM-5\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7402064/v1/fab3c1586855e47dd0e90c79.png"},{"id":90308991,"identity":"246f5b91-caa5-46db-82ac-f7fa300f23df","added_by":"auto","created_at":"2025-09-01 09:38:23","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":7385,"visible":true,"origin":"","legend":"\u003cp\u003eN\u003csub\u003e2\u003c/sub\u003e adsorption–desorption isotherm of HZSM-5\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7402064/v1/3ef14c9edcb0dff1aad28471.png"},{"id":90309013,"identity":"1aeb0432-2ffa-4e76-a628-488ee62449d2","added_by":"auto","created_at":"2025-09-01 09:38:25","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":19250,"visible":true,"origin":"","legend":"\u003cp\u003eTGA analysis results of spent catalysts at catalytic cracking of gasoil with catalyst loading weight of 0.3 gr\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7402064/v1/4bf3ee26811c0fad5cfa4409.png"},{"id":90308990,"identity":"a381de72-884d-410d-9d10-ca3226bbaba3","added_by":"auto","created_at":"2025-09-01 09:38:23","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":28797,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of (a) reaction temperature and (b) catalyst loading weight (%) on conversion of gasoil\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7402064/v1/f45e143d49d9d3155e1ae462.png"},{"id":90308980,"identity":"3a322dab-c81c-450e-9ea0-0a259c2220b7","added_by":"auto","created_at":"2025-09-01 09:38:22","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":24939,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of (a) reactor temperature and (b) catalyst loading weight on ethylene selectivity (wt.%)\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-7402064/v1/5916b8307c10928cd17dabce.png"},{"id":90308993,"identity":"41ad4fbe-5e39-4dc6-8cdb-d93ad610a733","added_by":"auto","created_at":"2025-09-01 09:38:23","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":23978,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of (a) reactor temperature and (b) catalyst loading weight on ethylene selectivity (wt.%)\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-7402064/v1/aeb75c49d8646b264bf3bce4.png"},{"id":90308970,"identity":"072040cb-162a-4b85-a87a-acdd92b2b129","added_by":"auto","created_at":"2025-09-01 09:38:21","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":28030,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of (a) reactor temperature and (b) catalyst loading weight on selectivity of light olefins (wt.%)\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-7402064/v1/8a297ce3278480a4d4ae059e.png"},{"id":90308975,"identity":"203e2ef8-05e3-4b8b-a50c-3ebb2ce231fd","added_by":"auto","created_at":"2025-09-01 09:38:22","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":14956,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of reactor temperature and catalyst loading weight on Methane selectivity (wt.%)\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-7402064/v1/9d01af59b039553f3fa8e993.png"},{"id":90309012,"identity":"e03575f9-183d-421a-818d-bc7a4779623f","added_by":"auto","created_at":"2025-09-01 09:38:25","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":16183,"visible":true,"origin":"","legend":"\u003cp\u003estability graph of catalytic cracking of gasoil over HZSM-5 at T=500 °C and catalyst loading weight=0.3 gr\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-7402064/v1/737452558d28ad036f4f0774.png"},{"id":90310853,"identity":"897e9131-2e32-4e15-9bfc-bbe7c10caff5","added_by":"auto","created_at":"2025-09-01 09:46:23","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":9212,"visible":true,"origin":"","legend":"\u003cp\u003econversion of gasoil over HZSM-5 at T=500°C and catalyst loading weight=o.3 gr\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-7402064/v1/fee71c07785ece47508c5bac.png"},{"id":92268077,"identity":"fbd559b4-55db-47e8-adaf-299d3b6260d3","added_by":"auto","created_at":"2025-09-26 13:55:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1015449,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7402064/v1/f294db3b-6b5e-4143-b91f-0895309737c3.pdf"}],"financialInterests":"","formattedTitle":"Optimization of Operational Parameters for Improved Light Olefin Production in Gasoil Cracking over HZSM-5 Catalyst: Temperature and Catalyst Loading Weight as Key Parameters","fulltext":[{"header":"1. INTRODUCTION","content":"\u003cp\u003eThe chemical industry depends considerably on light olefins- especially propylene and ethylene- as the necessary building blocks for the manufacturing of various chemicals and polyolefins \u003csup\u003e[1\u0026ndash;3]\u003c/sup\u003e. Among them, ethylene appears to be the most in-demand light olefin on the global market, with an annual production of 155\u0026nbsp;million tons \u003csup\u003e[4]\u003c/sup\u003e. However, the ongoing increase in propylene products worldwide could potentially exceed ethylene in the market in the future \u003csup\u003e[5]\u003c/sup\u003e. The substantial rise in propylene consumption is primarily driven by the increasing demand for its main downstream product, polypropylene \u003csup\u003e[6]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eCurrently, both ethylene and propylene are primarily produced as major by-products of naphtha steam cracking, a process that accounts for over 80% of total light olefins production. Light hydrocarbons, such as ethane, or light oils, such as naphtha and light cycle oil, are used as feedstock in this process. However, because of the increasing demand worldwide, there is a shortage of light oil supplies. Therefore, it is better to use heavier feedstock when making light olefins \u003csup\u003e[7]\u003c/sup\u003e. The type of feedstock used and the operating parameters have a significant effect on the product yield of steam cracking. Steam cracking, the most energy-intensive process in the petrochemical sector, produces much CO\u003csub\u003e2\u003c/sub\u003e and can reach reaction temperatures of up to 800\u0026deg;C [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Including a catalyst during hydrocarbon cracking reduces the temperature as well as decreasing CO\u003csub\u003e2\u003c/sub\u003e emission [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. On the other hand, catalytic cracking provides significant flexibility and high propylene selectivity at around 500\u0026deg;C [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Fluid Catalytic Cracking (FCC) remains vital in today\u0026rsquo;s market due to its capability to produce valuable light olefins (ethylene, propylene, butenes) and aromatics from hydrocarbons [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. In order to increase the production yield of particular products or prevent undesired side reactions, shape-selective catalysts such as zeolites is essential in catalytic cracking [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Among zeolites, ZSM-5 stands out due to its exceptional activity, hydrothermal stability, and resistance to carbon deposition [\u003cspan additionalcitationids=\"CR17 CR18 CR19\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. The effect of ZSM-5 additives on the selectivity of FCC products has been the subject of numerous investigations [\u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. In most cases it is reported that the ZSM-5 can improve the light olefins yields when used in FCC operation [\u003cspan additionalcitationids=\"CR25\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Because of its porous nature, ZSM-5 exhibits remarkable shape-selective catalytic activity [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Aside from its catalytic role, ZSM-5 can act as an effective sorbent because of its high surface area and microporous structure gives the ability to selectively adsorb and separate hydrocarbon species [\u003cspan additionalcitationids=\"CR30\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Additionally, its active Bronsted acid sites are identified as the active catalytic sites that account for the promotion of the cracking reaction [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. The feed characteristics, operating environment, and catalysts all have a significant effect on the amount of FCC propylene. Operating parameters, particularly temperature, significantly influence the distribution of products [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eOptimization of a process involves altering the process to maximize an identified number of parameters while maintaining a particular set of constraints. It is frequently employed to increase the production cost-efficiency, productivity and throughput [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Various studies have surveyed the conversion of naphtha [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], gasoil cracking, or other feedstock over ZSM-5 in order to increase the yield of light olefins by adjusting these factors [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Apart from assessing various feedstocks, scientists have also evaluated how important operational parameters\u0026mdash;like reaction temperature, residence time, and weight hourly space velocity (WHSV)\u0026mdash;affect product distribution. These parameters are essential in order to maximize the production of valuable light olefins like ethylene and propylene and optimize reaction pathways. Feng et al. studied how reaction temperature affects the catalytic cracking of naphtha over F/HZSM-5 reporting the yield of ethylene and propylene by temperature [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. Lu et al.'s work on CrHZSM-5 zeolites highlights the importance of reaction temperature in enhancing light olefin yield in isobutane cracking [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. Zhao et al. also found that temperature was a major variable determining light olefins selectivity in the catalytic cracking of gasoil [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. Despite the fact that ZSM-5 has been thoroughly investigated in FCC and naphtha cracking, performance in gasoil cracking at different temperatures and catalyst loadings- particularly as a pure zeolite without combination with Y zeolite or metal loading- has not been explored. To fill this gap, the present work attempts to investigate the effects of reactor temperature and catalyst loading weight on feed conversion and light olefin selectivity during catalytic gasoil cracking over HZSM-5 catalyst.\u003c/p\u003e"},{"header":"2. EXPERIMENTAL","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1. Catalyst preparation\u003c/h2\u003e\u003cp\u003eIn this study, a commercial sample of Na-ZSM-5 zeolite having a SiO₂/Al₂O₃ molar ratio of 36 was used as the parent catalyst material. The catalyst was then ion-exchanged to get the proton form according to ref. [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. For this purpose, 5 g of Na-ZSM-5 was added to 150 ml of 1 M ammonium nitrate solution and stirred for three hours on the heater at 80\u0026deg;C under the reflux. Then, the solution was filtered and washed with a specific volume of 80\u0026deg;C deionized water. The sample was subsequently dried at 110\u0026deg;C, and this procedure was repeated two more times. Finally, it was calcined for four hours at 550\u0026deg;C in static air to transform the NH\u003csub\u003e4\u003c/sub\u003e-ZSM-5 catalyst into HZSM-5. The resulting catalyst was shaped into cylindrical pellets (3 mm in diameter and 5 mm in height) using 3% bentonite as binder, followed by drying at 110\u0026deg;C for 12 hours.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2. Characterization\u003c/h2\u003e\u003cp\u003eXRD patterns were recorded on a PW1730 PHILIPS diffractometer with Cu Ka radiation at 40 kV and 30 mA, and a scanning rate of 1 sec. Textural properties of the samples were determined by nitrogen adsorption-desorption isotherms using the Belsorp mini II instrument (Japan). Before conducting the adsorption measurements, samples were degassed for two hours at 120\u0026deg;C. The specific surface areas of the samples were calculated based on the BET isothermal equation. Pore size distribution was calculated by using Barrett\u0026ndash;Joyner\u0026ndash;Halenda (BJH) method while micropore surface area, micropore volume and external surface area were evaluated using the t-plot method. The morphology of the samples was characterized using a MIRA/TESCAN scanning electron microscope. The silicon and aluminum contents in ZSM-5 were determined using X-ray fluorescence (XRF) analysis.\u003c/p\u003e\u003cp\u003eThermogravimetric analysis (TGA) was conducted on the spent catalysts using a STA6000 analyzer, with the temperature programmed from 40\u0026deg;C to 950\u0026deg;C under a nitrogen atmosphere at a constant heating rate of 10\u0026deg;C per minute. The gaseous products were analyzed using a gas chromatography (Agilent Technologies 7890A GC) equipped with HP-Plot/Q (30 m, 0.53 mm, 40 \u0026micro;m) capillary column and FID detector.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3. Experimental setup\u003c/h2\u003e\u003cp\u003eGasoil from the Tabriz Oil Refinery was injected into a Pyrex round-bottom vessel at a regulated flow rate of 2.74 mL/h using a syringe pump (702 SM Titrino, Metrohm). The atmospheric gasoil used in this investigation had a density of 0.832 g/cm\u0026sup3; and a boiling range of 170\u0026deg;C to 361\u0026deg;C. Its detailed properties are listed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Nitrogen was employed as the carrier gas and introduced into the Pyrex round-bottom vessel at a controlled flow rate, regulated by a flowmeter. The tubular reactor (10 mm inner diameter) was heated using a programmable furnace. Under constant nitrogen flow, the furnace was ramped up to the target temperature for each experiment at a rate of 10\u0026deg;C/min, and it was maintained there for the predetermined time. An electric mantle was used to heat the Pyrex round-bottom vessel once the reactor temperature had stabilized. Gasoil was then injected upon the temperature had reached the desired level. The vessel was maintained within a temperature range of 360\u0026ndash;362\u0026deg;C. The generated vapors flowed into the reactor and contacted the catalyst bed. To minimize heat loss, the vessel and associated connections were insulated with rock wool. The effluent from the reactor was quenched by one water-cooled condenser, followed by a decanter placed in an ice bath. After separating the products, the liquid products were collected, and the gas mixture was analyzed using the gas chromatography equipment. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e displays the schematic diagram of the experimental setup.\u003c/p\u003e\u003cp\u003eEach experiment was carried out for two hours to measure conversion and selectivity at different temperatures and catalyst loading weights. Based on gas chromatography (GC) data, the molar selectivity was calculated as the ratio of the moles of a particular product formed to the total moles of all products. Each component's molar selectivity (mol%) was multiplied by its corresponding molecular weight to determine the weight percentage selectivity (wt.%). The gas and liquid yields were computed using the following formulas:\u003c/p\u003e\u003cp\u003eY\u003csub\u003eliquid\u003c/sub\u003e = (weight of liquid) / (weight of feed) * 100%\u003c/p\u003e\u003cp\u003eY\u003csub\u003egas\u003c/sub\u003e = (weight of feed- weight of liquid) / (weight of feed) * 100%\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eproperties of gasoil as feedstock\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eProperties\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eValue\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDensity (gr/cm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.832\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eViscosity (cSt)\u003c/p\u003e\u003cp\u003eTotal sulfur (ppm)\u003c/p\u003e\u003cp\u003eRefractive Index (nD)\u003c/p\u003e\u003cp\u003eInitial Boiling Point (\u0026deg;C)\u003c/p\u003e\u003cp\u003e05%\u003c/p\u003e\u003cp\u003e10%\u003c/p\u003e\u003cp\u003e20%\u003c/p\u003e\u003cp\u003e30%\u003c/p\u003e\u003cp\u003e40%\u003c/p\u003e\u003cp\u003e50%\u003c/p\u003e\u003cp\u003e60%\u003c/p\u003e\u003cp\u003e70%\u003c/p\u003e\u003cp\u003e80%\u003c/p\u003e\u003cp\u003e90%\u003c/p\u003e\u003cp\u003e95%\u003c/p\u003e\u003cp\u003eFinal Boiling Point (\u0026deg;C)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e6.34\u003c/p\u003e\u003cp\u003e1\u003c/p\u003e\u003cp\u003e1.4555\u003c/p\u003e\u003cp\u003e170\u003c/p\u003e\u003cp\u003e182\u003c/p\u003e\u003cp\u003e189\u003c/p\u003e\u003cp\u003e201\u003c/p\u003e\u003cp\u003e217\u003c/p\u003e\u003cp\u003e235\u003c/p\u003e\u003cp\u003e250\u003c/p\u003e\u003cp\u003e273\u003c/p\u003e\u003cp\u003e286\u003c/p\u003e\u003cp\u003e306\u003c/p\u003e\u003cp\u003e330\u003c/p\u003e\u003cp\u003e349\u003c/p\u003e\u003cp\u003e361\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"3. RESULTS AND DISCUSSION","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e3.1. Catalyst characterization\u003c/h2\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the XRD patterns of the ion-exchanged ZSM-5 (HZSM-5) zeolite samples, which feature sharp peaks at 2θ\u0026thinsp;=\u0026thinsp;7\u0026ndash;9\u0026deg; and 22\u0026ndash;25\u0026deg;, characteristic of the MFI-type framework. These high crystallinity and phase purity peaks highlight no impurity peaks, so proving that the zeolite structure was maintained after the ion-exchange process [\u003cspan additionalcitationids=\"CR42\" citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eBoth samples display the distinctive hexagonal shape of ZSM-5 zeolite with particle sizes ranging from 1 to 3 \u0026micro;m (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The overall crystal morphology is essentially unchanged following ion exchange, suggesting that the zeolite's structural integrity was maintained. The surfaces of the HZSM-5 crystals stay smooth and show no signs of collapse or cracking, and they seem somewhat more compact. There is no discernible agglomeration or sintering, indicating that the particle morphology and crystallinity were not negatively impacted by the ion-exchange treatment.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe nitrogen adsorption\u0026ndash;desorption isotherm of HZSM-5 (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) is in accordance with the IUPAC Type IV classification, which is generally connected to mesoporous materials. The sample has a wide range of pores with different sizes. The sample contains pores with varying sizes across a broad spectrum. A summary of the physicochemical properties of the HZSM-5 catalyst, including its textural and structural properties that influence its catalytic performance in gasoil cracking, is given in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. XRF analysis revealed a slight decrease in the SiO\u003csub\u003e2\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ratio compared to the purchased commercial Na- ZSM-5, following the ion exchange process, suggesting that limited silicon was removed from the zeolite framework. It also indicates an intermediate acidic level, which maintains the acid density needed in cracking reactions and suppresses unwanted coke formation.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eTextural properties of HZSM-5 catalyst\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003ecatalyst\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSiO\u003csub\u003e2\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e molar ratio\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eBET surface area (m\u003csup\u003e2\u003c/sup\u003e/gr)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eTotal pore volume (cm\u003csup\u003e3\u003c/sup\u003e/gr)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAverage pore diameter (nm)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHZSM-5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e45.60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.052\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e4.56\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThermogravimetric analysis was employed to compare the extent of coke formation on three spent catalysts that were operated at different temperatures with the catalyst loading weight of 0.3 gr: 500\u0026deg;C, 550\u0026deg;C, and 600\u0026deg;C. The weight loss (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e) from coke burning, calculated based on the initial and residual weights, was 8.87%, 9.72%, and 9.25% for the 500\u0026deg;C, 550\u0026deg;C, and 600\u0026deg;C treated catalyst, respectively. Normalized to the initial sample weights of 21.869 mg, 24.284 mg, and 18.220 mg, the real amounts of coke were determined to be approximately 1.94 mg, 2.36 mg, and 1.69 mg, respectively. The maximum coke deposition at 550 \u0026deg; C indicates that this temperature can favor secondary reactions toward the formation of additional coke. However, at 600\u0026deg;C, the coke content is the lowest, which could be explained by increased gas-phase cracking and coke gasification processes that suppress coke accumulation. This interpretation suggests that the reaction temperature strongly influences the degree of catalyst deactivation through coke formation.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e3.2. Catalytic results\u003c/h2\u003e\u003cdiv id=\"Sec9\" class=\"Section3\"\u003e\u003ch2\u003e3.2.1. Impact of process variables\u003c/h2\u003e\u003cp\u003eInitial identification of critical process parameters is necessary for effective optimization. Based on the prior experiences, we took into account the following process variables with catalytic cracking: (i) reactor temperature; (ii) catalyst loading weight. These parameters were varied between 500 and 600\u0026deg;C (a typical operating range for gasoil cracking over zeolite catalysts), and 0.1 and 0.5 g, respectively and the experiments were repeated twice [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The effect of the mentioned variables on gasoil conversion, ethylene selectivity, propylene selectivity, and total selectivity of ethylene and propylene were investigated. Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e displays the obtained experimental values where the results are the average values from the two independent measurements conducted under identical conditions.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003edata for catalytic cracking of gasoil over HZSM-5 catalyst at different temperatures and catalyst loading weights\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTest order\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTemperature (\u0026deg;C)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCatalyst loading weight (gr)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eEthylene selectivity (wt. %)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003ePropylene selectivity (wt. %)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eEthylene\u0026thinsp;+\u0026thinsp;Propyelen selectivity (wt %)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003ePropylene/Ethylene\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eConv (1hr)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e500\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e10.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e33.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e43.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e3.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e81.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e550\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e13.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e36.61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e50.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e77.76\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e600\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e15.27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e39.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e54.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e81.29\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e500\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e11.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e32.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e53.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.91\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e87.40\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e550\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e14.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e36.13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e58. 78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e84.00\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e600\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e18.03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e37.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e58.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e87.47\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e500\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e9.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e31.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e30.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e3.42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e81.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e550\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e15.13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e38.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e40.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e81.31\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e600\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e19.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e41.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e45.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e87.34\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e(a) represents the relationship of gasoil conversion (wt.%) versus reaction temperature under varying catalyst loading weights. Catalytic cracking of gasoil within a temperature range of 500 to 600\u0026deg;C displays distinctive patterns of conversion depending on the catalyst loading weights. For the smallest catalyst loading weight (0.1 gr), conversion is a U-shaped function of temperature with a steep fall at 550\u0026deg;C. This decrease is probably the result of deficiency in active sites and the start of coke formation, which is common in cracking of gasoil over zeolites which partially deactivates the catalyst. For an intermediate catalyst loading weight of 0.3 gr, the minimum conversion occurs at 550\u0026deg;C because there is maximum coke formation. This result is consistent with the literature that coke formation at medium temperatures is likely to cause the pore blockage in the catalyst and hence coverage of active sites, thereby reduced catalytic activity. Coke, formed from polyaromatic intermediates, can deposit on the external surface or within the mesopores of the cylindrical pellets, blocking access to active sites. The HZSM-5 used in this study, with a mesoporous structure (~\u0026thinsp;4.6 nm), will be expected to minimize the severe pore blockage compared to traditional microporous ZSM-5 (~\u0026thinsp;0.5\u0026ndash;0.6 nm). At 600\u0026deg;C, there is a moderate loss in coke content correlated with conversion recovery, presumably due to partial coke gasification or enhanced coke resistance at elevated temperatures, both of which enhance active site availability. Alternatively, the highest loading of the catalyst (0.5 g) shows a smooth increase in conversion with temperature. This agrees with previous studies confirming that higher C/O ratios can help reduce coke- related catalyst deactivation by the presence of surplus active sites and coke dispersion or burn-off. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e(b), the amount of catalyst affects the conversion at different reaction temperatures. The highest conversion occurs at 0.3 g for both 500\u0026deg;C and 550\u0026deg;C. Despite the observed conversion trends across the temperature range, statistical analysis verified that temperature did not have a significant effect on conversion between 500\u0026deg;C and 600\u0026deg;C but the catalyst loading weight exerted a more dominant influence on conversion under the conditions studied.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eTo obtain a better understanding of the product distribution, the impact of temperature and catalyst loading weight on product selectivity were examined. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(a) shows the selectivity of ethylene versus temperature. The selectivity graph of ethylene illustrates a monotonic increase with temperature, indicating that thermal cracking predominates as the primary mechanism for ethylene formation [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. Furthermore, the 0.5 gr catalyst exhibits the most pronounced rate of temperature-induced increase in ethylene selectivity, suggesting that temperature and catalyst loading weight synergistically promote the formation of ethylene. Under the thermal cracking process and findings from the literature, higher catalyst-to-oil ratios result in higher light olefin yields because they have more active sites and better control over secondary reactions. Temperature and catalyst loading weight also increase ethylene selectivity. In line with these conclusions, Zhao et al. discovered that an increase in ZSM-5 leads to a linear increase in ethylene production in addition to a notable increase in propylene and butene yields [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e shows the propylene selectivity graph. Since propylene is an intermediate species, moderate reaction conditions yield the highest yield. Propylene selectivity increased steadily with temperature across all catalyst loading weights, reaching a maximum of 600\u0026deg;C. According to reports in the literature, propylene formation typically peaks between 550\u0026deg;C and 600\u0026deg;C, which is consistent with this pattern. Since propylene is an intermediate species, its maximum yield occurs under mild reaction conditions. After that, selectivity may decline due to increased secondary cracking and hydrogen transfer reactions that convert light olefins into lighter gases or saturated hydrocarbons [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. Even though higher temperatures were not examined in this work, the observed maximum at 600\u0026deg;C suggests that this temperature may be close to the optimal conditions for maximizing propylene yield under the given circumstances. According to the data, ethylene selectivity rises as catalyst loading weight does. This trend differs in the case of propylene, where the selectivity remains relatively constant, showing only minor fluctuations. This implies that propylene formation is less sensitive to the number of acid sites. Propylene always had the highest selectivity among the gas-phase products at all temperatures [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e], resulting in propylene-to-ethylene (P/E) ratios above two under all experimental conditions. Higher selectivity toward propylene suggests that the HZSM-5 catalyst's structural and acidic properties favored the formation of C\u003csub\u003e3\u003c/sub\u003e olefins over C\u003csub\u003e2\u003c/sub\u003e. However, as the temperature increased, the P/E ratio showed a declining trend, indicating that high thermal energy favors the formation of ethylene over propylene. Similar findings were reported by Kubo et al. [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e], who discovered that while the propylene-to-ethylene ratio decreased from 3 at 723 K to 1.4 at 923 K, higher ethylene and propylene selectivity was correlated with higher reaction temperatures. The variation of catalyst loading also had an impact on the P/E ratio; when the catalyst amount was raised from 0.1 to 0.3 gr, the P/E ratio dramatically dropped, indicating the improvement in ethylene yield generated by more active sites and increased cracking activity. Remarkably, a continued increase to 0.5 gr overturned this at the lower temperatures, perhaps due to diffusion limitation or coke deposition affecting ethylene selectivity. These results highlight the delicate balance between catalyst properties and reaction conditions in controlling product distribution in gasoil cracking.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe sum of the individual selectivities of ethylene and propylene was used to determine their total selectivity. There is a noticeable correlation between reactor temperature and catalyst loading weight and the selectivity of total light olefins. The total light olefins graph (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e) shows that raising the temperature from 500\u0026deg;C to 600\u0026deg;C improves light olefin selectivity for all catalyst loading weights [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. The highest overall selectivity is consistently achieved by 0.3 gr, peaking at about 59 wt.% at 550\u0026deg;C. A favorable thermal activation range for the synthesis of olefins is reflected in this behavior. The increase in the ratio of monomolecular cracking as opposed to traditional bimolecular cracking may be the primary cause of the selectivity shift with reaction temperature. Selectivity is somewhat reduced compared to 0.3 gr at higher catalyst loading weights (e.g., 0.5 gr), indicating that excessive catalyst loading may result in secondary reactions that lower olefin yield. The graphs for each product support these trends. Across all catalyst loading weights, ethylene selectivity increases steadily with temperature, peaking at roughly 20 wt. % at 600\u0026deg;C with 0.5 gr. This suggests that higher temperatures promote cracking pathways that favor the formation of ethylene. However, with selectivity values ranging from about 32 wt.% to about 42 wt.% propylene, dominates the light olefin distribution. Optimizing process conditions primarily increases propylene formation, while ethylene production plays a secondary but supportive role in the total olefin selectivities. It is reasonable to raise the reaction temperature in order to improve light olefin selectivity because the cracking reaction increases entropy [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAt all temperatures, methane selectivity (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e) declines as catalyst weight increases; the maximum selectivity was observed at 500\u0026deg;C and 0.1 g. Increased catalyst weight reduces the selectivity of methane by increasing contact time and active surface area, which promotes further conversion of methane into other products like CO or CO₂.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe objectives of the optimization study for gasoil catalytic cracking are to simultaneously maximize light olefins production and gasoil conversion along with the minimum coke formation [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eConsidering the results of temperature and catalyst loading weight variations, optimal conditions for subsequent experiments were established. We concluded that 500\u0026deg;C and 0.3 gr are the appropriate conditions due to their practical applications in industry. By operating the process at this particular temperature and catalyst quantity, coke formation is reduced, energy is saved, and a high conversion rate of 87% is achieved, ensuring stable reactor operation. According to the literature, the reactor temperature of 500\u0026deg;C is at the lower end of the typical range (500\u0026ndash;550\u0026deg;C) for the production of light olefins over HZSM-5 [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]. In operations where stability or wider product distributions are more important, 500\u0026deg;C is sometimes used, even though 525\u0026ndash;550\u0026deg;C is typically more characteristic of optimizing light olefin yield.\u003c/p\u003e\u003cp\u003eAs reported in the literature, the accumulation of coke on the catalyst's active sites contributes to a reduction in mass conversion [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e]. With regard to this deactivation mechanism, it is crucial to investigate how catalyst performance changes over time under fixed operating conditions. Accordingly, the light olefins selectivity, i.e., ethylene and propylene, and the feed conversion have been studied at the operation time between 0 and 360 min at a constant temperature of 500\u0026deg;C and catalyst weight of 0.3 gr. Figure\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e illustrates how the selectivity of ethylene and propylene is comparatively constant over the course of the 6-hour reaction, with only slight variations noted between 10 and 12%. This suggests that these lighter olefins are consistently produced under the specified conditions. The minor changes in ethylene and propylene selectivity also indicate that the catalyst was relatively stable during the whole period of time, as there have been no major deactivations nor changes in product distribution. In times where the selectivity is higher than that during the first hour, it may just be the result of temperature variations and heating vessel variable operations. The stability of ethylene and propylene selectivity over time is very similar to results in the literature of catalytic cracking of gasoil using HZSM-5 catalyst. The ZSM-5 zeolite has highly acidic, strongly shape selective, and thermally stable properties, which are incredibly beneficial for the continuous production of light olefins in the reaction condition. Numerous studies demonstrate that propylene selectivity remains high and stable over long reaction times when ZSM-5 is utilized as the main cracking catalyst or as an additive. For instance, a study by Corma et al. demonstrated that even when operational severity varies, the addition of ZSM-5 to fluid catalytic cracking (FCC) systems maintains propylene selectivity while increasing light olefin yields. Furthermore, hierarchical or nanoscale ZSM-5 structures have been shown to optimize ethylene formation while decreasing deactivation due to diffusion limitations and coke deposition [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe gas oil conversion pattern (Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e) over the ZSM-5 catalyst at 500\u0026deg;C and 0.3 gr catalyst loading weight showed an abrupt fall with time, from 70% at 60 minutes to 35% at 360 minutes. This suggests that the catalyst has been deactivated by coke deposited on the active acid sites. The initial sharp drop is typical of rapid coke formation followed by a less rapid deactivation stage as pore plugging and site poisoning still goes on. Similar phenomena have been documented in the literature. One article on the usage of HZSM-5 catalysts for the cracking of n-hexane mentioned coke deactivation after long-term operations, thus revealing the impact of coke on catalyst performance.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"4. CONCLUSION","content":"\u003cp\u003eThis experiment has researched the impact of reaction temperature and catalyst loading weight on gasoil conversion and light olefins production during catalytic cracking. The reaction temperature was found to be a significant factor. The conversion of gasoil reached a minimum at 550\u0026deg;C for catalyst weights of 0.1 and 0.3 gr, stated by experimental results. This was supported by the conception of the coke and the lack of acid sites that were not sufficient to continue the cracking reaction. A 0.5 g catalyst weight, on the other hand, showed a typical increasing conversion trend with temperature, most likely as a result of improved resistance to deactivation and increased active site availability. For all catalyst weights, the selectivity of light olefins, particularly ethylene and propylene, increased steadily with temperature, suggesting that higher temperatures favor the production of light olefins. Also, the conversion of gasoil was influenced by catalyst weight; the highest conversion was obtained with a catalyst loading weight of 0.3 gr. This is the indication of the ideal ratio of the combination of the acid sites that are present and the coke that is diminished. The total selectivity for light olefins also increased when the catalyst weight was raised, indicating that the active sites facilitate the formation of the targeted light olefins. The temperature of 500\u0026deg;C and a catalyst weight of 0.3 gr were selected as the best working conditions for further experiments. This option guarantees stable and efficient performance of the reactor by reducing coke formation, saving energy, and attaining a high conversion rate of 87%. In these conditions, the selectivity stayed constant during the 6-hour reaction time, but the conversion displayed a declining trend.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eConflict of interest statement\u003c/h2\u003e\u003cp\u003eOn behalf of all authors, the corresponding author states that there is no conflict of interest.\u003c/p\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eJung, J.S., T.J. Kim, and G. Seo, Catalytic cracking of n-octane over zeolites with different pore structures and acidities. Korean J. Chem. 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Res., 58(2019) 14695-14704. https://doi.org/10.1021/acs.iecr.9b02612\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Catalytic cracking, MFI zeolite, ZSM-5, Light olefins, Gasoil ","lastPublishedDoi":"10.21203/rs.3.rs-7402064/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7402064/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study investigates the catalytic cracking of gasoil over HZSM-5 zeolite with an emphasis on gasoil conversion and light olefin selectivity as a function of reaction conditions. For this purpose, the NaZSM-5 zeolite was ion-exchanged to make its protonated form. Then the resulting catalyst was used to evaluate the conversion, selectivity, and propylene/ethylene ratio in reactions carried out at 500, 550, and 600 °C temperatures with catalyst loading weights of 0.1, 0.3, and 0.5 gr. Both propylene and ethylene selectivity were enhanced by temperature across all catalyst weights, with the propylene enhancement being somewhat milder and a decreasing trend observed in the propylene-to-ethylene ratio. Catalyst weight dominated selectivity, with 0.3 gr producing the highest light olefins (53.57-58.78%), while 0.5 gr at 500 °C provided the lowest (30.55%), increasing secondary reactions. Conversion was maximum at 0.3 gr (87.47% at 600 °C), corresponding to light olefins formation.\u003c/p\u003e","manuscriptTitle":"Optimization of Operational Parameters for Improved Light Olefin Production in Gasoil Cracking over HZSM-5 Catalyst: Temperature and Catalyst Loading Weight as Key Parameters","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-01 09:38:11","doi":"10.21203/rs.3.rs-7402064/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9e1c8fb0-2ea6-4a5c-9e05-9536e23352ec","owner":[],"postedDate":"September 1st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-09-26T13:47:33+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-01 09:38:11","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7402064","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7402064","identity":"rs-7402064","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}