Investigation of HPW/TiO 2 -SnO 2 -ZrO 2 catalytic performance for epoxidation of soybean oil under hydrodynamic cavitation

Investigation of HPW/TiO 2 -SnO 2 -ZrO 2 catalytic performance for epoxidation of soybean oil under hydrodynamic cavitation | 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 Investigation of HPW/TiO 2 -SnO 2 -ZrO 2 catalytic performance for epoxidation of soybean oil under hydrodynamic cavitation Simin Mo, Qianwei Cheng, Xiaoli Wei, Tong Chen, Luli Meng, Gao Ming, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-2651546/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 05 May, 2023 Read the published version in Journal of Porous Materials → Version 1 posted 7 You are reading this latest preprint version Abstract BACKGROUND Epoxidized vegetable oils are widely used as plasticizers, lubricants and reaction intermediates. In this work, a new solid acid catalyst was developed to obtain epoxidized soybean oil in high yield and combined with hydrodynamic cavitation technology to improve the efficiency of epoxidation. The structure and morphology characteristics of the catalyst were studied by XRD, FT-IR, Py-FTIR, NH 3 -TPD, SEM, N 2 -adsorption and desorption analysis and TG techniques. It was applied to the epoxidation of soybean oil, and the influence of various parameters including catalyst dosage, formic acid dosage, hydrogen peroxide dosage and reaction temperature on the relative conversion rate of oxirane of soybean oil, as well as the recyclability of catalyst was studied. RESULTS The catalyst has both Lewis and Brönsted acid sites and is stable at high temperatures. Under the optimum reaction conditions, the relative conversion rate of oxirane was 85.08% at 2h. The catalytic activity did not decrease significantly after 5 cycles of the reaction. CONCLUSION The results show that the catalyst is easy to prepare, has good catalytic activity in catalyzing the epoxidation reaction of soybean oil, and is easy to recover and highly reusable. soybean oil epoxidation solid acid catalyst hydrodynamic cavitation 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 Figure 13 Figure 14 Figure 15 1. Introduction Traditionally, the industry mainly used phthalate products as plasticizers. The substances were easy to enter the human body to produce toxic, and in the manufacturing and burning process will produce carcinogenic substances. Therefore, the development of green plasticizers has become a hot spot for research in the chemical field.The epoxy plasticizer prepared by using renewable resources such as animal and vegetable oils can meet the above requirements well, and it has the advantages of good heat and light resistance, low volatility and non-toxicity, etc. [ 1 , 2 ] In addition, epoxidized vegetable oils could be widely used as plasticizers, stabilizers, lubricants and intermediates for polyurethanes. Therefore, it is necessary to develop effective technologies to improve the efficiency of epoxidation . [ 3 ] In epoxidation reaction, liquid acid catalyst, solid acid catalyst and enzyme catalyst are usually used to catalyze the reaction. [ 4 ] In recent years, solid acids have received much attention because they have fewer side reactions, less corrosion of reaction equipment and environmental pollution, and are easily separated and recovered from the products, solving the problem of catalyst regeneration. [ 5 , 6 ] Phosphotungstic acid (HPW) is used in a range of acid-catalyzed reactions such as ester exchange, oxidation, acylation, alkylation, polymerization, and dehydration reactions because of its acidity and environmental friendliness. [ 7 ] However, the problem of HPW being easily lost in the reaction system and not favorable for recycling limits its application. To solve this problem, researchers have loaded phosphotungstic acid onto molecular sieves or metal oxides with high specific surface area. [ 8 , 9 ] Due to the large specific surface area and acid site of honeycomb SnO 2 , Xie et al. [ 10 ] prepared multiphase CaO-SnO 2 catalyst by impregnation method, which was used to catalyze the transesterification reaction of soybean oil and methanol, and achieved a high conversion rate. ZrO 2 is commonly used as a catalyst carrier because it has both acidic and basic sites, [ 11 ] and its high specific surface area property can improve the dispersion of the loaded active substance, which in turn improves the catalyst activity and stability. [ 12 ] It has been reported that the addition of TiO 2 in the preparation of catalysts can not only increase the acidic sites of catalysts, but TiO 2 is also considered as a good catalyst carrier, which can have strong interactions with the active components. [ 13 ] In addition, studies have pointed out that the catalytic performance of a single oxide can be improved through mixing. For example, the strong interaction between TiO 2 and ZrO 2 can improve the strong acid-base performance, high thermal stability and strong mechanical strength of TiO 2 -ZrO 2 . [ 14 , 15 ] When explored the hydrolysis/dehydration of lignocellulosic biomass in hot-pressed water, Chareonlimkun and colleagues [ 16 ] found that TiO 2 -ZrO 2 binary oxide achieved a higher catalytic effect compared to a single oxide, due to a synergistic effect between the alkaline site of ZrO 2 and the acidic site of TiO 2 . Rong et al. [ 17 ] efficiently degraded glucose to 5-hydroxymethylfurfural using an excellent solid acid HPA/TiO 2 -ZrO 2 with high catalytic activity after five cycles. However, solid acid catalysis is susceptible to mass transfer limitations and gradual deactivation of the catalyst surface by the accumulation of products and their by-products, which may be responsible for limiting solid acid catalysis in practical large-scale applications. To solve this problem, many researchers have been trying to introduce cavitation into the reaction system to improve the catalytic efficiency. [ 18 – 20 ] Cavitation is the formation, growth and violent implosion of vapor bubbles in a liquid medium. [ 21 ] As the fluid passes through constricted sections such as orifice plates and venturi tubes, it causes a local drop in fluid pressure, and when the static pressure of the fluid drops below the saturated vapor pressure, the fluid vaporizes and the vaporized molecules form cavitation bubbles that subsequently burst when the downstream pressure recovers. [ 22 ] The bubble rupture during cavitation releases a large amount of energy, which can lead to water cleavage to produce free radicals, and can also generate high speed microjets and strong shock waves, which may be responsible for cleaning the catalyst surface and allowing the reaction system to be well mixed. [ 23 ] As far as we know, there are few studies on applyed hydrodynamic cavitation technology to epoxidation reaction. In this study, several metal oxides were combined to prepare a novel HPW/TiO 2 -SnO 2 -ZrO 2 solid acid catalyst, which would be easy to recycle, reduce the corrosion of device and have little pollution to the environment. It was applied to the catalytic soybean oil epoxidation reaction in combination with hydrocavitation technology to study the effects of different catalyst dosages, formic acid dosages, H 2 O 2 dosages and reaction temperatures on the relative conversion of epoxy values under the conditions of the new hydrocavitation technology, and recycling tests were conducted to explore the reusability of solid acid catalysts to make the reaction more environmentally friendly and economical. 2. Experimental 2.1. Materials Soybean oil purchased from Yihai Kerry Food Sales Company. Zirconium oxychloride (ZrOCl 2 ·8H 2 O) was purchased from Shanghai Maclin Biochemical Technology Co., Ltd. Phosphotungstic acid (H 3 PW 12 O 40 ) was purchased from Sinopril Chemical Reagent Co., Ltd. Titanium dioxide (TiO 2 ) was purchased from Tianjin Kermeo Chemical Reagent Co., Ltd. Tin tetrachloride (SnCl 4 ·5H 2 O), ammonium hydroxide(NH 3 ·H 2 O)(28wt%), hydrogen peroxide (H 2 O 2 )(30wt%), formic acid (HCOOH) (88wt%), hydrochloric acid and acetone were all purchased from Xilong Scientific Co.,Ltd. 2.2. Experimental equipments The hydraulic cavitation device is shown in Fig. 1 , which is a circulation system composed of oil-free air compressor (WP1100-2/65, Zhejiang Weipu Mechanical & Electrical Technology Co., Ltd.), pneumatic double diaphragm pump (JBB150/0.3, Shanghai Gaojin Fluid Technology Co., Ltd.), throttle valve, three-port flask, venturi tube and water bath kettle. Venturi tube is the main cavitation device, the inlet and outlet diameter is 20 mm, the throat length is 4 mm, the throat diameter is 5 mm, the inlet cone Angle is 40°, the outlet cone Angle is 30°. 14 mm plastic pipe is used to connect all pipes. The throttle valve is installed in the pipeline of oil-free air compressor to regulate the circulation flow of the pipeline. 2.3. Catalyst preparation The catalyst was prepared by coprecipitation-impregnation method. [ 24 ] The preparation process was as follows: Firstly, 1 gram of SnCl 4 ·5H 2 O and 7.2 grams of ZrOCl 2 ·8H 2 O were respectively dissolved in 20mL water, and 28wt% ammonium hydroxide were slowly added to adjust pH = 9. The two solutions were mixed, stirred at a rate of 300 r/min for 1h, and then aged for 12 h. The filter cake was repeatedly washed with distilled water (until all Cl − was washed away), dried at 110℃ for 8 h, and then ground and calcined at 550℃ for 2 h in muffle furnace to obtain SnO 2 -ZrO 2 precursor. 1.25g HPW was dissolved in 30mL distilled water and fully stirred to dissolve. Then 1.25g TiO 2 and 5g SnO 2 -ZrO 2 were added to the solution and stirred for 2h at a rate of 300 r/min at room temperature. After dryed the mixture at 110℃ for 8h, it was calcined at 600℃ for 5 h in muffle furnace to obtained HPW/TiO 2 -SnO 2 -ZrO 2 solid acid catalyst. For comparison, HPW/ SnO 2 -ZrO 2 was also prepared by the same method, and only the step of added TiO 2 was removed during the preparation process. 2.4. Catalyst characterization The crystal structure of the sample was characterized by Bruker D8A A25 X-ray diffraction instrument. The XRD working conditions were as follows: generator power 9KW, scanning step size 0.02°, scanning speed 0.01°/s, scanning range 2θ = 5 ~ 80°. KBr tablet method was used to test the samples (surface groups in qualitative catalyst) with Frontier infrared spectrometer. The wave number ranged from 4000 to 400 cm − 1 . Zeiss Merlin scanning electron microscope (SEM) was used to detect the micromorphology of the sample particles. The Py-FTIR spectra of the samples were recorded by nicolet 380 Fourier transform infrared spectrometer, and the types of acid sites on the solid acid surface were analyzed. XPS tests were performed using Thermo Fisher Scientific K-Alpha. Among them, the vacuum of the analysis room is 5xL0-10Pa, the excitation source is Al Ka ray (HV = 1486.68 eV), the working voltage is 15kV, the filament current is 10mA, and the signal is accumulated for 5–10 cycles. The Passing Energy was 50eV and the step length was 0.05 eV, and the charge correction was carried out according to the Energy standard of C1s = 284.80 eV. ASAP2020M + C automatic microporous physicochemical adsorption apparatus was used to measure the surface area and pore size distribution of the catalyst. The samples were pretreated at 300℃ for 4 h prior to nitrogen adsorption-desorption determination. Surface area and pore size were calculated by using Brunauer-Emmett -Teller (BET) equations and the Barrett-Joyner-Halenda (BJH) equations, respectively. TG-DTG measurements were conducted with a STA449F5 synchronous thermal analyzer instrument in an atmosphere of flowing dry air. The samples were heated from room temperature to 1073K at the heating rate of 10K/min. The acid strength of the catalyst was determined by ammonia temperature-programmed desorption in TP-5080-B instrument. 2.5. Catalyst-activity test The catalytic performance of the catalyst in the epoxidation of soybean oil (SBO) was evaluated. First, 300 g soybean oil, 0.5wt% solid acid (measured by the mass of soybean oil) and formic acid were put into a three-port round-bottom flask and stirred evenly. Then, the hydrodynamic cavitation device was started to start the cycle reaction and hydrogen peroxide was added drop by drop (the addition of hydrogen peroxide was controlled within 10 min), where n (double bond): n (hydrogen peroxide): n (formic acid) = 1:2.4:1.2. Start the timer when the hydrogen peroxide drops are added finished. The reaction temperature was controlled at 55 ± 1℃. Epoxidized soybean oil was sampled and separated by centrifugation after each sampled. The obtained catalysts were washed with methanol and distilled water in turn for recovery and utilization. The obtained solution was washed with 3% sodium hydroxide solution and warm distilled water to neutral. And then the liquid was further distilled under reduced pressure to obtain epoxidized soybean oil (ESBO). Finally, the relative conversion of the samples to oxirane was analysed. All experiments were carried out in triplicate and the results are presented as average values. The oxygen content of ethylene oxide was determined with hydrochloric acid-acetone solution. [ 25 ] The relative conversion rate of oxirane (%RCO) was calculated according to the following equation: Where OOex (g/100g sample) is the experimentally determined content of oxirane oxygen, OOth is the theoretical maximum oxirane oxygen content in 100 g oil, which was 7.24% from the following equation : where A i (126.9) and A 0 (16.0) are the atomic weights of iodine and oxygen respectively, and IV 0 is the original iodine value of the oil sample. 3. Results And Discussion 3.1. Characterization of catalyst 3.1.1. X-ray diffraction The wide-angle XRD spectra of HPW/SnO 2 -ZrO 2 and HPW/TiO 2 -SnO 2 -ZrO 2 are shown in Fig. 2 . From the XRD diagram of HPW/SnO 2 -ZrO 2 , it could be observed that there are two structural stable phases of zirconia: monocline phase and tetragonal phase. The 2θ peaks at 24.1, 28.2, 31.4 and 34.1 belong to m-ZrO 2 (monoclinic phase), and the 2θ peaks at 35.2, 50.6 and 60.3 belong to t-ZrO 2 (tetragonal phase) . [ 26 , 27 ] However, no obvious SnO 2 diffraction peaks appeared in the spectrograph curve, indicated that SnO 2 exists in an amorphous state. Combined with the SEM figure (Fig. 6 ), it could be seen that SnO 2 has been evenly dispersed on the surface of ZrO 2 [ 28 ] . The diffraction peaks of HPW were not observed in the HPW/ SnO 2 -ZrO 2 spectrograph, indicated that HPW is well dispersed on the surface of SnO 2 -ZrO 2 . [ 29 ] The diffraction peaks of HPW/TiO 2 -SnO 2 -ZrO 2 spectra appeared at about 2θ = 25.6°, 37.9°, 48.3°, 53.8°, 55.0°, 62.7° and 75.0°, these diffraction peaks were attributed to anatase TiO 2 . It has been proved that anatase titanium dioxide show high catalytic activity. [ 16 ] In addition, HPW/TiO 2 -SnO 2 -ZrO 2 spectrum line showed that the typical characteristic peak of HPW/SnO 2 -ZrO 2 does not disappear, indicated that the main crystal structure of catalyst is complete before and after TiO 2 loaded. 3.1.2. FT-IR The FT-IR spectra of HPW/SnO 2 -ZrO 2 and HPW/TiO 2 -SnO 2 -ZrO 2 catalysts are shown in Fig. 3 a. As shown in the figure, for HPW/SnO 2 -ZrO 2 , bending vibration and stretching vibration peaks belonging to the H-O-H band adsorbed by water could be observed near 1635cm − 1 and between 3320-3500cm − 1 . [ 30 , 31 ] 1404.8 cm − 1 showed a band related to -OH groups, which is characteristic of metal oxides. [ 16 ] The characteristic peaks in the vicinity of 1086cm − 1 and 983.5cm − 1 can correspond to the absorption peaks of P-O a and W = O d of phosphotungstic acid, which are consistent with the literature, [ 32 , 33 ] indicated that phosphotungstic acid has been successfully loaded on SnO 2 -ZrO 2 . The absorption band of Zr-O-C stretching vibration was observed at 1030 cm − 1 , and two characteristic peaks were observed at 505 and 580 cm-1, both of which belong to Zr-O stretching vibration. [ 34 ] The observed peak at 670cm − 1 can be attributed to the Sn-O band . [ 34 ] The peak of Ti-O stretching vibration appears between 450 and 800cm − 1 . [ 35 ] For HPW/TiO 2 -SnO 2 -ZrO 2 , the peak strengthening at 500-800cm − 1 can be observed in the figure, which may be due to the superposition of Ti-O and Zr-O. It indicated that TiO 2 has been successfully doped to HPW/SnO 2 -ZrO 2 . In Fig. 3 b, the characteristic peaks at 3012, 1650 and 723 cm − 1 found in the SBO line are attributed to the stretching vibration of the double bond: C = CH, C = C, cis-CH = CH. After epoxidation, double bonds associated with 3012 cm − 1 and 1650 cm − 1 bands almost disappeared. This observation is consistent with the research results of Jianghao Wu et al., that the peak strength corresponding to C = CH tensile disappeared after epoxidation. [ 36 ] The peak intensity of ESBO unsaturated bond signal decreased at 723cm − 1 . In addition, the appearance of a new peak at 837 cm − 1 in the FT-IR spectrum of ESBO was attributed to the epoxy group (C-O-C), which confirmed the successful epoxidation of SBO [ 37 ] . 3.1.3. NH 3 -TPD The main desorption peaks of NH 3 in the temperature range of 100–300℃, 300–500℃ and 500–700℃ are related to the weak acid site, moderate acid site and strong acid site respectively. [ 38 ] Fig. 4 showed the NH 3 -TPD analysis results of HPW/SnO 2 -ZrO 2 and HPW/TiO 2 -SnO 2 -ZrO 2 catalysts. It could be clearly seen that, with the temperature rose from 50℃ to 800℃, HPW/SnO 2 -ZrO 2 curve has three peaks near 149.5℃, 405℃ and 606.7℃, corresponding to the desorption of NH 3 molecule at weak acid site, moderate acid site and strong acid site, respectively. Among them, desorption peaks at 149.5℃ and 606.7℃ could be attributed to HPW. [ 39 ] For HPW/TiO 2 -SnO 2 -ZrO 2 curves, there is also a weak acid site near 149.5℃, and a wide peak between 400–530℃, which corresponds to the moderate acid site, but the strong acid site decreased significantly. The number of acid sites on the surface was calculated by combining the desorption peak area of NH 3 -TPD. HPW/TiO 2 -SnO 2 -ZrO 2 (0.75 mmol/g) was higher than HPW/SnO 2 -ZrO 2 (0.60 mmol/g), indicated that the addition of TiO 2 could increase the total acid site of solid acid, but was not conducive to the strong acid site. 3.1.4. Py-FTIR Pyridine-FTIR studies were performed to distinguish the properties of acid sites in catalysts. These peaks are due to the interaction of pyridine with Brønsted(B) and Lewis(L) acid sites present on the catalyst surface. Liu et al. [ 29 ] found that the parent ZrO 2 was mainly Lewis acid site and the total acid content was low by compared the Py-FTIR of HPW loaded with 0–15% ZrO 2 . With the increase of HPW loaded, the total acidity of the catalyst increased, especially the Brønsted acid. It could be observed from Fig. 5 that absorption peaks appeared near 1610 cm − 1 and 1445 cm − 1 with high intensity, and these two peaks are typical characteristic peaks of Lewis acid sites. Among them, 1445 cm − 1 is the characteristic peak of Lewis acid site from Zr 4+ center. [ 14 ] A peak of weak Lewis acid sites appeared near 1577 cm − 1 , [ 40 ] which could be attributed to the skeletal Sn 4+ site. [ 41 ] Absorption peaks near 1537–1550 cm − 1 and 1640cm − 1 belong to Brønsted acid sites [ 42 ] , of which 1537–1550 cm − 1 is the characteristic peak of Brønsted acid sites from HPW. [ 14 ] The presence of 1640 cm − 1 Brønsted acid peak in the catalyst could be attributed to the Sn-OH group. [ 41 ] The absorption peak near 1490 cm − 1 could be attributed to the mixed characteristic peak of Lewis acid site and Brønsted acid site. [ 43 ] These results indicated that HPW/TiO 2 -SnO 2 -ZrO 2 catalyst contains both B and L acid sites . 3.1.5. SEM Figure 6 showed the SEM images of HPW/SnO 2 -ZrO 2 and HPW/TiO 2 -SnO 2 -ZrO 2 respectively. The image of HPW/SnO 2 -ZrO 2 (Fig. 6 a and b) reflected the catalyst is an irregular block with rough edges. There were small block SnO 2 and fine powder particles HPW evenly dispersed on the surface, and there are pores of different sizes between the particles. The image of HPW/TiO 2 -SnO 2 -ZrO 2 (Fig. 6 c and d) displayed that many new near-spherical particles were added on the irregular block surface of HPW/SnO 2 -ZrO 2 . These near-spherical particles are TiO 2 , indicated that TiO 2 has been successfully and uniformly loaded on HPW/SnO 2 -ZrO 2 . EDS results (Fig. 6 e) showed that the elements Sn, W and Ti were evenly distributed in the catalyst. This result supported the assumption from XRD results that HPW and SnO 2 are uniformly dispersed on the surface of the catalyst. 3.1.6. Nitrogen-adsorption-desorption Figure 7 showed the nitrogen adsorption isotherms of HPW/SnO 2 -ZrO 2 and HPW/TiO 2 -SnO 2 -ZrO 2 . As can be seen from the figure, both samples exhibited Ⅳ-type adsorption isotherm, which are typical characteristics of mesoporous materials according to IUPAC classification. The isotherms of HPW/SnO 2 -ZrO 2 show an H2-type hysteresis loop, indicated a uniform pore size distribution for this sample. With the addition of TiO 2 , its isotherm showed an H3-type hysteresis loop, indicated that the pore structure of this catalyst became irregular after the addition of TiO 2 .The pore size distributions image of the HPW/SnO 2 -ZrO 2 and HPW/TiO 2 -SnO 2 -ZrO 2 catalyst were calculated showed in Fig. 7 based on the desorption branch of the isotherms using the BJH method. The image showed that all samples had pore size distribution within the mesopore range approximately 9 nm to 16 nm. This also verified the pore structure seen in SEM images. The specific surface area of HPW/TiO 2 -SnO 2 -ZrO 2 was slightly higher than that of HPW/SnO 2 -ZrO 2 (63.1007m 2 /g vs 46.02142m 2 /g), indicated that the addition of TiO 2 was beneficial to increase the specific surface area of solid acid. 3.1.7. XPS The XPS diagrams of HPW/TiO 2 -SnO 2 -ZrO 2 are showed in Fig. 8 , and the full XPS spectrum of the catalyst indicated the presence of C, W, Ti, Sn and Zr elements(Fig. 8 a). Signal peaks at 284.9 eV in the C 1s XPS diagram(Fig. 8 b) was attributed to C-C bonds. W 4f XPS diagram in Fig. 8 c exhibited double peaks at 34.1 eV and 35.9 eV of the W 4f 7/2 and W 4f 5/2 assigned to intact HPW. This indicated that the phosphotungstic acid was successfully introduced to the HPW/TiO 2 -SnO 2 -ZrO 2 sample. [ 44 ] Ti 2p XPS diagram in Fig. 8 d exhibited double peaks located at 459.3 eV and 464.9 eV, related to Ti 2p3/2 and Ti 2p1/2 signals of Ti (IV) species, respectively. [ 43 ] The peak of 487.5 eV in Sn 3d XPS(Fig. 8 e) was devied from the SnO 2 . [ 45 , 46 ] Zr 3d XPS diagram in Fig. 8 f exhibited double peaks at 183.1 eV and 185.5 eV, which were attributed to Zr 3d3/2 and Zr 3d5/2, respectively. [ 14 ] XPS spectra showed that HPW, TiO 2 , SnO 2 and ZrO 2 exist in the catalyst. 3.1.8. TG The percentage weight loss of the catalyst is shown in Fig. 9 . Thermal degradation of solid acid catalyst was observed with increasing temperature, that is, the sample weight decreased slowly with increasing temperature. The first mass loss is below 100℃, and a sharp endothermic peak could be observed from the DTG curve near 25–100℃, indicated that the mass of catalyst droped rapidly at this position, and the weight loss in this part is mainly due to the removal of adsorptive water and air. [ 47 ] The gradual weight loss of the catalyst at 100–800℃ could be attributed to the gradual decomposition of HPW/TiO 2 -SnO 2 -ZrO 2 . Among them, mass loss after 400℃ is related to the decomposition of Keggin structure of phosphotungstic acid. [ 48 ] In conclusion, the total mass loss of the sample is only 5.28% in the range of 25–800℃, indicated that HPW/ TiO 2 -SnO 2 -ZrO 2 catalyst has good thermal stability at higher temperature. In this study, all reaction temperatures were below 100℃, so the catalyst met the temperature requirements for the epoxidation. 3.2. Catalytic activity 3.2.1. Effect of catalyst dosage The function of the catalyst is to catalyze H 2 O 2 and formic acid to form peroxyformic acid, and then peroxyformic acid as an epoxidation reagent to form epoxy bonds in soybean oil. Soybean oil was used as raw material, HPW/TiO 2 -SnO 2 -ZrO 2 was used as catalyst, under the conditions of n (double bond) : n (hydrogen peroxide) : n (formic acid) = 1 : 2.4 : 1.2 and reaction temperature of 55℃, the influence of catalyst dosage (measured by soybean oil quality) on the epoxidation reaction was investigated, as shown in Fig. 10 . At the initial stage of the reaction, the reaction speed was fast, and the conversion rate showed an increasing trend. The relative conversion rate of oxirane increased with the increase of the dosage of catalyst. When the dosage of catalyst was 1wt%, the RCO reached 83.15% at 3h. It indicated that increased the amount of catalyst could increased the concentration of active ingredients and speeded up the reaction. [ 49 ] Although the conversion rate was basically the same at 2.5h and 3h when the amount of catalyst was 0.5wt% and 1wt%, the conversion rate was higher in the first 2h when the amount of catalyst was 1wt%, indicated that the dosage of 1wt% could achieve better epoxidation effect in a relatively short time. In addition, further increased of catalyst dosage could easily pile up in the reaction system and reduced the contact between the active site and the reactants, led to the reduction of conversion rate. [ 49 ] Therefore, considered the catalytic effect and economic benefit, 1wt% catalyst dosage is the most appropriate. 3.2.2. Effect of formic acid dosage In the preparation reaction of ESBO, formic acid acts as an oxygen carrier, reacts with H 2 O 2 to generate peroxyformic acid, and then reacts with unsaturated groups in SBO molecular structure to generate ESBO. [ 50 ] Under the conditions of n (double bond) : n (H 2 O 2 ) = 1 : 2.4, catalyst dosage 1wt% and reaction temperature 55℃. The influence of formic acid dosage on RCO was investigated, and the results are shown in Fig. 11 . When the dosage of formic acid was increased from n (double bond): n (formic acid) = 1 : 0.9 to 1 : 1.8, the RCO increased rapidly from 68.65–82.46% at 2 h, while when the dosage of formic acid was further increased to 1: 2.1, the conversion rate of ESBO decreased to 80.39%. It indicated that appropriately increased the dosage of formic acid could increased the concentration of intermediate peroxyformic acid and promoted the generation of ethylene oxide group, thus improved RCO. [ 51 ] However, formic acid itself has certain acidity and strong reactivity. Therefore, excessive increased in the dosage of formic acid will lead to the instability of oxirane ring and accelerated the ring-opening side reaction between ESBO epoxy group and water, thus reducing the RCO value. [ 52 ] 3.2.3. Effect of fydrogen peroxide dosage As can be seen from Fig. 11 , with the increased of n (double bond): n (H 2 O 2 ) mole ratio, the conversion rate first increased and then decreased. The optimal n (double bond):n (H 2 O 2 ) mole ratio was 1: 3.2, which made the soybean oil conversion rate the highest, reached 85.08%. The reason may be that the increased in the dosage of hydrogen peroxide promoted the production of performic acid, which in turn promoted the formation of oxirane rings. [ 53 ] Too little or too much H 2 O 2 will affect the effect of epoxidation. Because too little H 2 O 2 will generate less peroxyformic acid, resulted in incomplete epoxidation reaction. However, excessive H 2 O 2 is also not conducive to the generation of epoxy products. Although the reaction speed of epoxidation is accelerated, it will also accelerated the side reaction in the epoxidation reaction process, led to the ring-opening of epoxy bonds. [ 54 ] Moreover, the increase of H 2 O 2 will reduced the acid activity in the water phase, thus reduced the overall activity of the catalyst, led to the reduction of the epoxidation efficiency. [ 55 ] 3.2.4. Effect of reaction temperatrue As can be seen from Fig. 13 that the RCO is low when the reaction is carried out at 45℃. With the increase of reaction temperature, the reaction speed became faster. When the reaction temperature rose to 55℃, the conversion rate increased significantly, reached 85.08% at 2h, because higher epoxidation reaction temperature is conducive to the formation of peroxyformic acid, which leaded to a faster epoxidation rate. [ 11 ] However, as the reaction temperature continued to rise and the epoxidation speed increased, side reactions such as ring-opening were prone to occur, resulted in a trend of RCO value decline. This may be due to the decomposition of the resulted epoxides at higher reaction temperatures, thus formed more by-products, that is, the epoxide products in acidic systems are unstable at high reaction temperatures. [ 56 ] So Under the conditions of n (double bond) : n (H 2 O 2 ) : n (HCOOH) = 1 : 3.2 : 1.8 and catalyst dosage of 1wt%, the reaction temperature of 55℃ is suitable, the reaction speed is fast, and the conversion rate is the highest, which is 85.08%. 3.3. Comparison of hydrodynamic cavitation (HC) and mechanical stirring (MS) Under the conditions of n(C = C): n (H 2 O 2 ): n(HCOOH) = 1:3.2:1.8, the dosage of catalyst is 1wt%, and the temperature is 55℃, the advantages of solid acid catalysis are studied compared with without catalyst. As shown in Fig. 14 , used the conventional mechanical stirring method at 300 r/min, the rate of epoxidation was slow and the RCO value did not reach 70% at 3h of reaction. It may be due to the fact that the mechanical stirring method is mainly based on the cutting force provided by the blade rotation to achieve the two-phase mixing, which is less effective in mass transfer between reactants and can cause dead zones on the stirred tank walls. [ 57 ] The collapse of the cavitation-generated vacuoles could impact the two-phase interface, increase the contact opportunities between the reacting substances, accelerate the renewal of the phase surface and enhance the effect of mass transfer. In the study, the conversion rate could reach 79.97% at 3h when only hydrodynamic cavitation was used without the addition of catalyst, which also proved that hydrodynamic cavitation could accelerate the rate of epoxidation reaction and increased the epoxy value of the product. The relative conversion of oxirane of soybean oil could reach 85.08% in 2h when solid acid catalyzed epoxidation was enhanced by hydrodynamic cavitation technology, which shortened the reaction time and improved the epoxidation efficiency at the same time, due to the fact that hydrodynamic cavitation technology not only promoted the mixing between reactants, but also continuously refreshed the catalyst surface by generated micro-jets and shock waves, and prevented the catalyst particles from aggregating, thus increasing the effective surface area of the catalyst to improve the overall reaction efficiency. [ 58 ] 3.4. Reusability of HPW/TiO 2 -SnO 2 -ZrO 2 The reusability of the catalyst is a critical factor catalysts in the epoxidation. Used soybean oil as raw material, HPW/TiO 2 -SnO 2 -ZrO 2 as catalyst, n (C = C) : n (H 2 O 2 ) : n(HCOOH) = 1:2.4:1.2, and the reaction temperature was 55℃, the reusability of the catalyst was investigated. At the end of each experiment, the catalyst was cleaned with methanol and distilled water to remove the adsorbed reactants on the surface of the catalyst. After dryed at 105℃ for 5h, the catalyst was transferred to muffle furnace for calcined at 500℃ for 3 h, and then applied to the next experiment. The experimental results are shown in Fig. 15 . The RCO of soybean oil at 3h of epoxidation reaction decreased slightly from 83.15–80.52% after five consecutive cycles, and only decreased by 2.59%. Therefore, the catalyst showed excellent stability and good repeatability. In addition, FT-IR images (Fig. 15 b) of catalysts before and after use were compared, and the infrared images of the catalysts after calcined at 500℃ for 3h were basically the same as those before use, indicated that wash and calcination can remove the adsorbed organic part in the reaction process, [ 59 ] which indicated that the structure of catalysts was stable. According to the SEM figure (Fig. 15 c and d), the morphological structure and porous characteristics of the solid acid catalyst remain unchanged, which is an important reason why the catalyst still maintains good activity after 5 cycles. 4. Conclusion This work highlights the enhanced epoxidation of soybean oil catalyzed by HPW/TiO 2 -SnO 2 -ZrO 2 used hydrodynamic cavitation and optimizes the effects of various process parameters. The optimized parameters were as follows: catalyst dosage is 1wt%, n(C = C): n(HCOOH) = 1:1.8, n(C = C):n(H 2 O 2 ) = 1:3.2, temperature 55 ℃. Under these optimized conditions, the highest relative conversion of oxirane of 85.08% was found for 2h of reaction under hydrocavitation-enhanced solid acid catalysis. In contrast, the epoxidation reaction without the addition of catalyst or used the conventional mechanical stirring method could not achieve an RCO value of 80% even after 3 h of reaction. In addition, it was observed that the catalyst was heterogeneous and stable, and the epoxidation effect did not decrease significantly after repeated used for 5 times. The results indicated that the catalyst can be used to catalyze the epoxidation of soybean oil and improve the epoxidation efficiency effectively. Declarations CRediT authorship contribution statement Simin Mo: Data curation, Formal analysis, Methodology, Visualization, Writing-original draft. Qianwei Cheng: Supervision, Resources, Funding acquisition, Project administration. Xiaoli Wei: Conceptualization, Formal analysis. Tong Chen: Supervision, Formal analysis. Luli Meng: Conceptualization, Formal analysis, Visualization. Gao Ming: Formal analysis,Visualization. Kena Yu: Visualization. Acknowledgement This work was supported by the Guangxi Natural Science Foundation Project [2020GXNSFAA159101]. Conflicts of interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Data availability All data used in this study are available upon request from the corresponding author. 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Supplementary Files Graphicalabstract.png Graphical abstract HPW/TiO 2 -SnO 2 -ZrO 2 catalyst was synthesized, which has high efficiency and good reusability, and can be used for the epoxidation of soybean oil. Cite Share Download PDF Status: Published Journal Publication published 05 May, 2023 Read the published version in Journal of Porous Materials → Version 1 posted Editorial decision: Major revision 02 Apr, 2023 Reviews received at journal 15 Mar, 2023 Reviewers agreed at journal 10 Mar, 2023 Reviewers invited by journal 10 Mar, 2023 Editor assigned by journal 06 Mar, 2023 Submission checks completed at journal 06 Mar, 2023 First submitted to journal 03 Mar, 2023 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. 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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-2651546","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":181159843,"identity":"7f177ad4-fb53-4f99-ba39-a0bb46ca09b3","order_by":0,"name":"Simin Mo","email":"","orcid":"","institution":"Guangxi University of Science and Technology","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Simin","middleName":"","lastName":"Mo","suffix":""},{"id":181159844,"identity":"ee4fd51f-8aff-4fae-addb-8262e6f87214","order_by":1,"name":"Qianwei Cheng","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABE0lEQVRIie2QMUvDQBSAXziIy9mudxzmNxwEouCfsQTsYnELHWIICJnEOaD4G5wypxxcltJbMzhYhM46WDKoeAm2LtfQUfA+jjd8vI8HB2Cx/EVQN0n3AKYb7e6dzDeqL9nSJk62RzKo0OoFT09geHctl+8PV6NHpUp4jYQ2qTGhwj328ZwAeZJj/6iofF6H4OQLoU1pTLiAgE0yApxcBIwW0uM1AnSYCW3OdiQHazb5apPLNaP3EnMlAH32JlhfSbsrLn1LY4+XISCnJ6ECR+xDEkzq84CBLH1ah3x2sxhrY04GqipoHifeMA9XtImT0a2aLZ+b6FQbcwI/v4LbgTCIrcTm/d+kw2kg2blosVgs/5dvZYVZF5rXfiMAAAAASUVORK5CYII=","orcid":"","institution":"Guangxi University of Science and Technology","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Qianwei","middleName":"","lastName":"Cheng","suffix":""},{"id":181159845,"identity":"171209ed-70e5-4d0b-914e-d4e6a84aa292","order_by":2,"name":"Xiaoli Wei","email":"","orcid":"","institution":"Liuzhou institute of technology","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Xiaoli","middleName":"","lastName":"Wei","suffix":""},{"id":181159847,"identity":"894dd418-eab9-4855-a917-9dbcb195c4ff","order_by":3,"name":"Tong Chen","email":"","orcid":"","institution":"Guangxi University of Science and Technology","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Tong","middleName":"","lastName":"Chen","suffix":""},{"id":181159850,"identity":"1c8850fc-faec-412b-b696-eb6ed6c4292f","order_by":4,"name":"Luli Meng","email":"","orcid":"","institution":"Guangxi University of Science and Technology","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Luli","middleName":"","lastName":"Meng","suffix":""},{"id":181159852,"identity":"fad15f3b-475d-4d25-b6c7-36d0706e1b58","order_by":5,"name":"Gao Ming","email":"","orcid":"","institution":"Guangxi University of Science and Technology","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Gao","middleName":"","lastName":"Ming","suffix":""},{"id":181159853,"identity":"8ac824e6-c8ae-4323-8034-eb94738646fb","order_by":6,"name":"Kena Yu","email":"","orcid":"","institution":"Guangxi University of Science and Technology","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Kena","middleName":"","lastName":"Yu","suffix":""}],"badges":[],"createdAt":"2023-03-03 12:44:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-2651546/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-2651546/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10934-023-01466-8","type":"published","date":"2023-05-05T20:42:12+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":34193132,"identity":"ca477878-541f-4951-98ea-4bc50ed6e6a6","added_by":"auto","created_at":"2023-03-13 22:42:15","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":74733,"visible":true,"origin":"","legend":"\u003cp\u003eWork principles sketch map of the hydrodynamic cavitation experiment device\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/ae9335b272820ba8969a3172.png"},{"id":34193136,"identity":"8f811141-7c3b-4231-b300-69ef621243bf","added_by":"auto","created_at":"2023-03-13 22:42:15","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":90803,"visible":true,"origin":"","legend":"\u003cp\u003eLow angle X-ray diffraction (XRD) patterns for samples: HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e; HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/a65705cc83be6ef4fe34cf34.png"},{"id":34194870,"identity":"ebad8a84-388d-4e64-8341-d411f2ec6681","added_by":"auto","created_at":"2023-03-13 22:58:15","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":100905,"visible":true,"origin":"","legend":"\u003cp\u003eFT-IR spectra of (a) the prepared catalysts; (b) soybean oil (SBO) and epoxidized soybean oil (ESBO)\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/5fb182d3cc961eae64baf663.png"},{"id":34194869,"identity":"a2441186-8ec2-4650-944c-f97d1bdbc620","added_by":"auto","created_at":"2023-03-13 22:58:15","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":67053,"visible":true,"origin":"","legend":"\u003cp\u003eNH\u003csub\u003e3\u003c/sub\u003e-TPD profile of the prepared catalysts\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/25d3bbf69246f69b710cb79b.png"},{"id":34193853,"identity":"88ac5b3a-c560-4c5b-b61e-920aa0c5e353","added_by":"auto","created_at":"2023-03-13 22:50:15","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":87040,"visible":true,"origin":"","legend":"\u003cp\u003ePy-FTIR profile of HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2 \u003c/sub\u003ecatalyst. Pyridine adsorbed on Brønsted (B), Lewis (L), strong Lewis (SL), and weak Lewis (WL) acid sites are indicated\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/ca2e007d72924f13d43e1a23.png"},{"id":34193141,"identity":"3ccdbfbd-5e3d-4a6f-838e-f78473e46504","added_by":"auto","created_at":"2023-03-13 22:42:15","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":751450,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of (a-b) HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e; (c-d) HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e; and(e) elemental mapping pictures of HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/7798f902deb485727b085420.png"},{"id":34196086,"identity":"011bf514-14d8-4d2a-987f-3faa25553483","added_by":"auto","created_at":"2023-03-13 23:06:15","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":102269,"visible":true,"origin":"","legend":"\u003cp\u003eNitrogen adsorption isotherms and pore size distribution profiles of (a)HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u0026nbsp; \u003c/sub\u003eand (b) HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/cbb40fde261a9156deaad5fc.png"},{"id":34193860,"identity":"381ba014-dcf6-489b-ad95-a47fc2152400","added_by":"auto","created_at":"2023-03-13 22:50:15","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":160623,"visible":true,"origin":"","legend":"\u003cp\u003eXPS diagrams of HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e:(a) Full spectrum, (b) C 1s, (c)W 4f,\u003c/p\u003e\n\u003cp\u003e(d)Ti 2p, (e) Sn 3d, (f)Zr 3d.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/f75c4633cedcbac4a4db727f.png"},{"id":34193138,"identity":"2cd9695e-2814-4403-b633-ac2d1d9748c7","added_by":"auto","created_at":"2023-03-13 22:42:15","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":73397,"visible":true,"origin":"","legend":"\u003cp\u003eTG images of HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e catalyst\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/0679e70223c3e98338d2514e.png"},{"id":34193857,"identity":"d4378003-7c28-4f73-a3a6-9f0f5b169f73","added_by":"auto","created_at":"2023-03-13 22:50:15","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":78190,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of catalyst dosage on the conversion for epoxidation\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/af085072d841961ea96771a9.png"},{"id":34193143,"identity":"9181f7ea-975f-44d9-a09f-d1eb8ab22f1f","added_by":"auto","created_at":"2023-03-13 22:42:15","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":76179,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of formic acid dosage on the conversion for epoxidation\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/a923689fb8009ed5d179e027.png"},{"id":34193145,"identity":"d37f1de3-5270-458a-b7ea-9e21d9c4a703","added_by":"auto","created_at":"2023-03-13 22:42:15","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":73050,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of fydrogen peroxide dosage on the conversion for epoxidation\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/a9dc7bb8c45af1d7493643e6.png"},{"id":34196087,"identity":"2f3ba600-04c6-46cd-b4fa-3a2f288725f7","added_by":"auto","created_at":"2023-03-13 23:06:15","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":74383,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of reaction temperatrue on the conversion for epoxidation\u003c/p\u003e","description":"","filename":"13.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/e16d2b4775b0c96441dc1faa.png"},{"id":34193147,"identity":"12d0669c-a9ef-48cf-a05f-c7e129ab634c","added_by":"auto","created_at":"2023-03-13 22:42:15","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":125805,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of HC with MS under optimum operating condition\u003c/p\u003e","description":"","filename":"14.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/68635e939f04a169ec3b8abd.png"},{"id":34193858,"identity":"b17640af-bb01-4f52-866c-43df5c52f876","added_by":"auto","created_at":"2023-03-13 22:50:15","extension":"png","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":285211,"visible":true,"origin":"","legend":"\u003cp\u003e(a) The reused results of HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e, (b) FT-IR spectra of recovered HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e, (c-d) SEM spectra of recovered HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e","description":"","filename":"15.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/59a11a7a1f163ac18d3839f6.png"},{"id":44728238,"identity":"14b904fe-cdc9-4ee2-89fa-cbc616f0e38c","added_by":"auto","created_at":"2023-10-16 21:02:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2442813,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/3f1b43af-837b-49f9-a6b2-9e63cbd16bad.pdf"},{"id":34193133,"identity":"38e33168-8774-4685-884c-a07e5ea5b905","added_by":"auto","created_at":"2023-03-13 22:42:15","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":52691,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGraphical abstract\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eHPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e catalyst was synthesized, which has high efficiency and good reusability, and can be used for the epoxidation of soybean oil.\u003c/p\u003e","description":"","filename":"Graphicalabstract.png","url":"https://assets-eu.researchsquare.com/files/rs-2651546/v1/097fb674043077d2380e0d62.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"Investigation of HPW/TiO 2 -SnO 2 -ZrO 2 catalytic performance for epoxidation of soybean oil under hydrodynamic cavitation","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eTraditionally, the industry mainly used phthalate products as plasticizers. The substances were easy to enter the human body to produce toxic, and in the manufacturing and burning process will produce carcinogenic substances. Therefore, the development of green plasticizers has become a hot spot for research in the chemical field.The epoxy plasticizer prepared by using renewable resources such as animal and vegetable oils can meet the above requirements well, and it has the advantages of good heat and light resistance, low volatility and non-toxicity, etc.\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003eIn addition, epoxidized vegetable oils could be widely used as plasticizers, stabilizers, lubricants and intermediates for polyurethanes. Therefore, it is necessary to develop effective technologies to improve the efficiency of epoxidation .\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eIn epoxidation reaction, liquid acid catalyst, solid acid catalyst and enzyme catalyst are usually used to catalyze the reaction.\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e In recent years, solid acids have received much attention because they have fewer side reactions, less corrosion of reaction equipment and environmental pollution, and are easily separated and recovered from the products, solving the problem of catalyst regeneration.\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e Phosphotungstic acid (HPW) is used in a range of acid-catalyzed reactions such as ester exchange, oxidation, acylation, alkylation, polymerization, and dehydration reactions because of its acidity and environmental friendliness.\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e However, the problem of HPW being easily lost in the reaction system and not favorable for recycling limits its application. To solve this problem, researchers have loaded phosphotungstic acid onto molecular sieves or metal oxides with high specific surface area. \u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e Due to the large specific surface area and acid site of honeycomb SnO\u003csub\u003e2\u003c/sub\u003e, Xie et al. \u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e prepared multiphase CaO-SnO\u003csub\u003e2\u003c/sub\u003e catalyst by impregnation method, which was used to catalyze the transesterification reaction of soybean oil and methanol, and achieved a high conversion rate. ZrO\u003csub\u003e2\u003c/sub\u003e is commonly used as a catalyst carrier because it has both acidic and basic sites, \u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e and its high specific surface area property can improve the dispersion of the loaded active substance, which in turn improves the catalyst activity and stability. \u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e It has been reported that the addition of TiO\u003csub\u003e2\u003c/sub\u003e in the preparation of catalysts can not only increase the acidic sites of catalysts, but TiO\u003csub\u003e2\u003c/sub\u003e is also considered as a good catalyst carrier, which can have strong interactions with the active components.\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e In addition, studies have pointed out that the catalytic performance of a single oxide can be improved through mixing. For example, the strong interaction between TiO\u003csub\u003e2\u003c/sub\u003e and ZrO\u003csub\u003e2\u003c/sub\u003e can improve the strong acid-base performance, high thermal stability and strong mechanical strength of TiO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e.\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e When explored the hydrolysis/dehydration of lignocellulosic biomass in hot-pressed water, Chareonlimkun and colleagues \u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e found that TiO\u003csub\u003e2\u003c/sub\u003e -ZrO\u003csub\u003e2\u003c/sub\u003e binary oxide achieved a higher catalytic effect compared to a single oxide, due to a synergistic effect between the alkaline site of ZrO\u003csub\u003e2\u003c/sub\u003e and the acidic site of TiO\u003csub\u003e2\u003c/sub\u003e. Rong et al. \u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e efficiently degraded glucose to 5-hydroxymethylfurfural using an excellent solid acid HPA/TiO\u003csub\u003e2\u003c/sub\u003e -ZrO\u003csub\u003e2\u003c/sub\u003e with high catalytic activity after five cycles. However, solid acid catalysis is susceptible to mass transfer limitations and gradual deactivation of the catalyst surface by the accumulation of products and their by-products, which may be responsible for limiting solid acid catalysis in practical large-scale applications.\u003c/p\u003e \u003cp\u003eTo solve this problem, many researchers have been trying to introduce cavitation into the reaction system to improve the catalytic efficiency.\u003csup\u003e[\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e Cavitation is the formation, growth and violent implosion of vapor bubbles in a liquid medium.\u003csup\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e As the fluid passes through constricted sections such as orifice plates and venturi tubes, it causes a local drop in fluid pressure, and when the static pressure of the fluid drops below the saturated vapor pressure, the fluid vaporizes and the vaporized molecules form cavitation bubbles that subsequently burst when the downstream pressure recovers.\u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e The bubble rupture during cavitation releases a large amount of energy, which can lead to water cleavage to produce free radicals, and can also generate high speed microjets and strong shock waves, which may be responsible for cleaning the catalyst surface and allowing the reaction system to be well mixed.\u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e As far as we know, there are few studies on applyed hydrodynamic cavitation technology to epoxidation reaction.\u003c/p\u003e \u003cp\u003eIn this study, several metal oxides were combined to prepare a novel HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e solid acid catalyst, which would be easy to recycle, reduce the corrosion of device and have little pollution to the environment. It was applied to the catalytic soybean oil epoxidation reaction in combination with hydrocavitation technology to study the effects of different catalyst dosages, formic acid dosages, H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e dosages and reaction temperatures on the relative conversion of epoxy values under the conditions of the new hydrocavitation technology, and recycling tests were conducted to explore the reusability of solid acid catalysts to make the reaction more environmentally friendly and economical.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Materials\u003c/h2\u003e \u003cp\u003eSoybean oil purchased from Yihai Kerry Food Sales Company. Zirconium oxychloride (ZrOCl\u003csub\u003e2\u003c/sub\u003e\u0026middot;8H\u003csub\u003e2\u003c/sub\u003eO) was purchased from Shanghai Maclin Biochemical Technology Co., Ltd. Phosphotungstic acid (H\u003csub\u003e3\u003c/sub\u003ePW\u003csub\u003e12\u003c/sub\u003eO\u003csub\u003e40\u003c/sub\u003e) was purchased from Sinopril Chemical Reagent Co., Ltd. Titanium dioxide (TiO\u003csub\u003e2\u003c/sub\u003e) was purchased from Tianjin Kermeo Chemical Reagent Co., Ltd. Tin tetrachloride (SnCl\u003csub\u003e4\u003c/sub\u003e\u0026middot;5H\u003csub\u003e2\u003c/sub\u003eO), ammonium hydroxide(NH\u003csub\u003e3\u003c/sub\u003e\u0026middot;H\u003csub\u003e2\u003c/sub\u003eO)(28wt%), hydrogen peroxide (H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e)(30wt%), formic acid (HCOOH) (88wt%), hydrochloric acid and acetone were all purchased from Xilong Scientific Co.,Ltd.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Experimental equipments\u003c/h2\u003e \u003cp\u003eThe hydraulic cavitation device is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, which is a circulation system composed of oil-free air compressor (WP1100-2/65, Zhejiang Weipu Mechanical \u0026amp; Electrical Technology Co., Ltd.), pneumatic double diaphragm pump (JBB150/0.3, Shanghai Gaojin Fluid Technology Co., Ltd.), throttle valve, three-port flask, venturi tube and water bath kettle. Venturi tube is the main cavitation device, the inlet and outlet diameter is 20 mm, the throat length is 4 mm, the throat diameter is 5 mm, the inlet cone Angle is 40\u0026deg;, the outlet cone Angle is 30\u0026deg;. 14 mm plastic pipe is used to connect all pipes. The throttle valve is installed in the pipeline of oil-free air compressor to regulate the circulation flow of the pipeline.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Catalyst preparation\u003c/h2\u003e \u003cp\u003eThe catalyst was prepared by coprecipitation-impregnation method.\u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e The preparation process was as follows: Firstly, 1 gram of SnCl\u003csub\u003e4\u003c/sub\u003e\u0026middot;5H\u003csub\u003e2\u003c/sub\u003eO and 7.2 grams of ZrOCl\u003csub\u003e2\u003c/sub\u003e\u0026middot;8H\u003csub\u003e2\u003c/sub\u003eO were respectively dissolved in 20mL water, and 28wt% ammonium hydroxide were slowly added to adjust pH\u0026thinsp;=\u0026thinsp;9. The two solutions were mixed, stirred at a rate of 300 r/min for 1h, and then aged for 12 h. The filter cake was repeatedly washed with distilled water (until all Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e was washed away), dried at 110℃ for 8 h, and then ground and calcined at 550℃ for 2 h in muffle furnace to obtain SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e precursor.\u003c/p\u003e \u003cp\u003e1.25g HPW was dissolved in 30mL distilled water and fully stirred to dissolve. Then 1.25g TiO\u003csub\u003e2\u003c/sub\u003e and 5g SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e were added to the solution and stirred for 2h at a rate of 300 r/min at room temperature. After dryed the mixture at 110℃ for 8h, it was calcined at 600℃ for 5 h in muffle furnace to obtained HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e solid acid catalyst. For comparison, HPW/ SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e was also prepared by the same method, and only the step of added TiO\u003csub\u003e2\u003c/sub\u003e was removed during the preparation process.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Catalyst characterization\u003c/h2\u003e \u003cp\u003eThe crystal structure of the sample was characterized by Bruker D8A A25 X-ray diffraction instrument. The XRD working conditions were as follows: generator power 9KW, scanning step size 0.02\u0026deg;, scanning speed 0.01\u0026deg;/s, scanning range 2θ\u0026thinsp;=\u0026thinsp;5\u0026thinsp;~\u0026thinsp;80\u0026deg;. KBr tablet method was used to test the samples (surface groups in qualitative catalyst) with Frontier infrared spectrometer. The wave number ranged from 4000 to 400 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Zeiss Merlin scanning electron microscope (SEM) was used to detect the micromorphology of the sample particles. The Py-FTIR spectra of the samples were recorded by nicolet 380 Fourier transform infrared spectrometer, and the types of acid sites on the solid acid surface were analyzed. XPS tests were performed using Thermo Fisher Scientific K-Alpha. Among them, the vacuum of the analysis room is 5xL0-10Pa, the excitation source is Al Ka ray (HV\u0026thinsp;=\u0026thinsp;1486.68 eV), the working voltage is 15kV, the filament current is 10mA, and the signal is accumulated for 5\u0026ndash;10 cycles. The Passing Energy was 50eV and the step length was 0.05 eV, and the charge correction was carried out according to the Energy standard of C1s\u0026thinsp;=\u0026thinsp;284.80 eV. ASAP2020M\u0026thinsp;+\u0026thinsp;C automatic microporous physicochemical adsorption apparatus was used to measure the surface area and pore size distribution of the catalyst. The samples were pretreated at 300℃ for 4 h prior to nitrogen adsorption-desorption determination. Surface area and pore size were calculated by using Brunauer-Emmett -Teller (BET) equations and the Barrett-Joyner-Halenda (BJH) equations, respectively. TG-DTG measurements were conducted with a STA449F5 synchronous thermal analyzer instrument in an atmosphere of flowing dry air. The samples were heated from room temperature to 1073K at the heating rate of 10K/min. The acid strength of the catalyst was determined by ammonia temperature-programmed desorption in TP-5080-B instrument.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5. Catalyst-activity test\u003c/h2\u003e \u003cp\u003eThe catalytic performance of the catalyst in the epoxidation of soybean oil (SBO) was evaluated. First, 300 g soybean oil, 0.5wt% solid acid (measured by the mass of soybean oil) and formic acid were put into a three-port round-bottom flask and stirred evenly. Then, the hydrodynamic cavitation device was started to start the cycle reaction and hydrogen peroxide was added drop by drop (the addition of hydrogen peroxide was controlled within 10 min), where n (double bond): n (hydrogen peroxide): n (formic acid)\u0026thinsp;=\u0026thinsp;1:2.4:1.2. Start the timer when the hydrogen peroxide drops are added finished. The reaction temperature was controlled at 55\u0026thinsp;\u0026plusmn;\u0026thinsp;1℃. Epoxidized soybean oil was sampled and separated by centrifugation after each sampled. The obtained catalysts were washed with methanol and distilled water in turn for recovery and utilization. The obtained solution was washed with 3% sodium hydroxide solution and warm distilled water to neutral. And then the liquid was further distilled under reduced pressure to obtain epoxidized soybean oil (ESBO). Finally, the relative conversion of the samples to oxirane was analysed. All experiments were carried out in triplicate and the results are presented as average values.\u003c/p\u003e \u003cp\u003eThe oxygen content of ethylene oxide was determined with hydrochloric acid-acetone solution.\u003csup\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e The relative conversion rate of oxirane (%RCO) was calculated according to the following equation:\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\" width=\"477\" height=\"56\"\u003e\u003cbr\u003e\u003c/p\u003e\u003cp\u003eWhere OOex (g/100g sample) is the experimentally determined content of oxirane oxygen, OOth is the theoretical maximum oxirane oxygen content in 100 g oil, which was 7.24% from the following equation :\u003c/p\u003e\u003cp\u003e\u003cimg src=\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAaYAAAA5CAYAAAB9No8hAAALnElEQVR4nO2dPW/bSBeFj168vyMIYsqFoHoLKttsFcmNKiGdtyJhN3IRp3LpxquGbAKInZpsoIqNyd0tttjY+gWCCnESpNq/MVtQH/z+kGmLts4DsDA55Axticd35t7DhpRSghBCCKkJ/9v3AAghhJAgFCZCCCG1gsJECCGkVlCYCCGE1AoKEyGEkFpBYSKEEFIrKEyEEEJqBYWJEEJIraAwEUIIqRUUJkIIIbWCwkQIIaRWUJieBS70hg43uEdvoNHYbh3ThdkJ79NXJwizE2gnyveuh/vejineV2GECT02lvh9EkIOEEnqjaNJQJNOwiHPUCWgSsMLNlcT2nvSUCE1x5PlcaSmRXv3pKFu+/DHARlrlsp6PEmHDKlG7okQclgwYqo1LvQe4MgxuglHvcUM0K4wVLb7mi0AWj/c3h1hMfAw7ioojWsD/Ujv7i0w2Y5JGU5gqIBlF4t1XP0UF7OUg8oQ994A0yYjJ0IOFQpTjXH1HubGZaIoAS5sC9AiouEtIk98YUK3+xgPdxAlJOsSukOEL6fguF30gjqW/QFUqGg1U9ooQ0yMOXql5wcJIS8BClNtcWFbKgYnKYIilpjHHu4CyzmgbnYKmKMF+uMUadPz1p1c2OinCGO836hIxpuZ0JeXGGKBGdo4Dt2agKmbWI9EORlAtWxGTYQcIBSmuuLasGIP7y3idoqZOkBYtzwsZkB7dZIwT4HL5GlAuDp6cCClxNXiFInalBguJQ4GUxi4zGwqYN4eZ0RuCobjITZHlWO0YaHg7CAh5AVBYaopYjnPOorb6Qzq4AThoCMQRbk6RpggTQfEcr6JcLr9Nqa3cWUqqkvuaIrBZIisyUJXb+Lioudn8fUsQG1hG+wJP6MwYepuviyfRUgIed5QmJ4j4hbTWcI0n7eeInOh2y1cZqwrxdaiYhSbxhNmB3b/PlUA/UvpsPsSUvqbo0UbKDgZaPlTgYSQg4DCVFOUjGyC5Gm8VZSlAkvdRn+cHcE0W2r2AMQSrTyhcHWcYoLNEpYwYUaDntW6UmyZq30cGJ/A7TQ5OmunzWUSQl4sFKa60u1DwxyxmSzhYnSRMI2HVRQ0s7Dop6wrBVCO25v0bteex6IvcQscZ13E1dHoWZhdNLdFvc1F6Bzh6uiMEIncXNi+foY6m7Yj0ZlYYg6t0FQiIeSFUXlllOdJR1OlCkgAElDTCzvLtJVSSulIrVQh5y74xZ9Yj0k15L5qPR0NUg1Umq4LWTdb5BcRbV/k+kDSOZ40tPT7jo0jNh7/77Tev7m+o4Xbr3+3jiZVzZDBP71nqLH7e0pC9/iYnwHPkFrl1cSrz3DKuIP3lvQrzjtOyGNTrTA5mlQBqRrO5gvhrR5GsQ94mbb+CZuH3ZMIUy2+kY7UDtIFwZFaitvFU+MZ6iMKU4YDxs4E/ilIGnfISSThH72844Q8AdUJ00pokiIeR4t8SQq3jXxxPWN1XmWjTqBOwiQP0KKnXg/DxxQm3z7qce41edwJQuho6d+32HFCttzc3Mjff/9dSinl0dHRJsr++vWrlFLKr1+/yrOzs52uXdEakwu9Z2GmOem2N7MFvNJt/bqcg0YZ4l5eYXEQFj0u9IaNvpTxZInaIGB2Ev4WwkSnjFNFEQeMqvtcZXOG+mu2oM6muBUFjhOy4vz8HD9+/MD79+9xfn6Ov/76C1JK3Nzc4OeffwYAvH37Fq9fv8a7d+9KX78SYRLmNSyoMLIrLEu2daE3erAAWL0GGiHXabF10j4I25ouxil+eS+L53CfCob3fdhBoRAmOqfApKiaZjhgJLtxVNAnECgnCF76GG3MsPAKHCcEwN3dHb5//45Pnz4BAD59+oQ3b94AAD5+/AgA+P79++bnN2/e4MuXL6X6qECY/GJPJKQv+/iebr6xaJm2XYw9AyoAzZGQgQeW1TsFJhLS0QDrOtm1IHjVyCsiYttBiBupji7Gk5VQuCb0ETC5z07P35LhgJHpxvGQPgmpjuvra/z666+ZbdZCBQAfPnzA1dVVqT4eLkziFr7WxNOXAaysdVY+amXaZqA5q4LOZgs51TgAgO54W9yZuNV33ojUFaWL8aSF694UrcviApHlgJHrxrFjn5mIJbI8RnKPk4Pjzz//xE8//ZR47O7uDjc3N6F9a5FaR1FFeOQ6JgHz2gLUPB+1sm2DPM00Q2bExe1FbYUQLvTTBa6cARajrflsJjkOGLluHLv0GaTZgppUG7de58o7Tg6etbgEI6Ignz9/3kznRfn3338L9/NwYVKO0QYwS1AHYZ7iYqbCWPuolWlbIVVM5WVGXNxe1FbgEwX91Eb/foxud4jxJXDayRGKAg4Y2W4cO/QZRTnBQA3/IxdyEck7TkgG7969w4cPH6q5mKyA9ZtUt+nf3ioVVo2lwpZpG0sPz/u5EmqWLk72SjztOvz23kBDqaZ8ZrxVAXE45dqRmorwOY62+dw5WrBEoHyfsRKNYB+b/Sl1TFnHycEDQH779i207+zsbJMmvv45yNHRUeyczD4eNsQtnqGFHBxUzclwDijaNuLCEDjHcIzQNaqr86EwkS0Pq2Mq6YAhs9w4dusz6btB5wfyEM7Ozjb1S1KGa5jWW1Ckvn37Jo+Ojkr10ZCy0NzFASFgdpq4aDtMiiAQZgfN6QAeM+AIAeAnOFxfX+OPP/4o1P63337Dq1ev8P79+8J90MSVEEJIYd6+fYtffvkF5+fnuW2/fPmCv//+u5QoARSmdKxVSm9sgXlV3Juy8CzMziapIimnIu/4w3ChN+IOAdHkj47pbguUI2MJjq+TVyAW6yfNncKFntBXIYQJPTaO5Pt82DWjTfzfQ/Pi0K1HCInz8eNHvH79OrNw9u7uDv/880/hyCpERdOOB0KNDTJD146zTjoJrjf4SSfRc9Z+aWXXOBypJd5MeOF+vX5R7L4zTE539hB8DONUQkiVUJh24GkNMlMyskLku3E7WjyhI/HVEo6222sYHC35Ye8YEfEonlySa3LqGVIt6UL+mMaphJBq4FReVezRINPVe5gblxkec77VU9RRI1bQKUzodj/ZLidvDHbyG2jRHUZeu64g4+W8gQsWMDlVhpgYc/SKzg2WMk4lhOwLClNV7M0g04VtqbE30IYQS8xjD2OB5RxQNzsFzNEC/ZRMxGRz0cAY0C9ovur3m2k7lWFyCgiY+nZ9TzkZQLXs/PWm0saphJB9QWF67rg2rNjDO0xy9b7/SpH26kRhngKXKc7emeaiyAiXEgeDKbJspzJMTgEACobjQOq2cow2LNiZyrSrcSohZB9QmB6THQ0yw1l0TVzMLPRSLJTEMs9i03d0jxnnBqMoV8cIE6RpQZ65aBldckdTDDJsp7JMTjcZkQlTd/O4wVuha+YapxJCnhwKU1VUaJAZdkP3YKganKCfW5nC39XaVmyqbzO16EK3W7jMWFfKNhctPo0nzA7s/n2qAOaZnAIKTgZarvt8mWvmGqcSQp4cClNV7MkgU8nJJEjrQyzngAosdRv9cbarQaa5qFiiVUQoXB2nmGxNTIUJMxj4FDA59aO/5OisnTSX+WDjVELIPqAw7UDyf9kKhlcarOv1wryL0cUM2tX6oZ93fEe6fWiJkRgA4feR9P4rbzEDZhYW/fw3xirHbVirRRzXnoeiL3ELHOe+jFhHo2dhdtHcTkc2F5vzhKujM0IkanNh+9oZuJ9bTNuR6EwsMYcWE6ui18y6N0LInthXnvrzZB8Gmfl1TI4WN/0M9gPE64aSzski2VzUk0bMNTsy+ug4QuMpaXK6cukO1v7Ga7H2YZxKCKkSmri+CFzojWu0vIz1mxeJC71hoy/zoz5CyPPh//seAKmCLsbeEp1mBzgYcXKhN3qAIylKhLwwGDG9KA4lgjiU+yTkMKEwEUIIqRXMyiOEEFIrKEyEEEJqBYWJEEJIraAwEUIIqRUUJkIIIbWCwkQIIaRWUJgIIYTUiv8ARJwLeQnhg6YAAAAASUVORK5CYII=\" width=\"422\" height=\"57\"\u003e\u003cbr\u003e\u003c/p\u003e \u003cp\u003ewhere A\u003csub\u003ei\u003c/sub\u003e (126.9) and A\u003csub\u003e0\u003c/sub\u003e (16.0) are the atomic weights of iodine and oxygen respectively, and IV\u003csub\u003e0\u003c/sub\u003e is the original iodine value of the oil sample.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results And Discussion","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Characterization of catalyst\u003c/h2\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e3.1.1. X-ray diffraction\u003c/h2\u003e \u003cp\u003eThe wide-angle XRD spectra of HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e and HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. From the XRD diagram of HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e, it could be observed that there are two structural stable phases of zirconia: monocline phase and tetragonal phase. The 2θ peaks at 24.1, 28.2, 31.4 and 34.1 belong to m-ZrO\u003csub\u003e2\u003c/sub\u003e (monoclinic phase), and the 2θ peaks at 35.2, 50.6 and 60.3 belong to t-ZrO\u003csub\u003e2\u003c/sub\u003e (tetragonal phase) .\u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/sup\u003e However, no obvious SnO\u003csub\u003e2\u003c/sub\u003e diffraction peaks appeared in the spectrograph curve, indicated that SnO\u003csub\u003e2\u003c/sub\u003e exists in an amorphous state. Combined with the SEM figure (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e), it could be seen that SnO\u003csub\u003e2\u003c/sub\u003e has been evenly dispersed on the surface of ZrO\u003csub\u003e2\u003c/sub\u003e \u003csup\u003e[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/sup\u003e. The diffraction peaks of HPW were not observed in the HPW/ SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e spectrograph, indicated that HPW is well dispersed on the surface of SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e .\u003csup\u003e[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/sup\u003e The diffraction peaks of HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e spectra appeared at about 2θ\u0026thinsp;=\u0026thinsp;25.6\u0026deg;, 37.9\u0026deg;, 48.3\u0026deg;, 53.8\u0026deg;, 55.0\u0026deg;, 62.7\u0026deg; and 75.0\u0026deg;, these diffraction peaks were attributed to anatase TiO\u003csub\u003e2\u003c/sub\u003e. It has been proved that anatase titanium dioxide show high catalytic activity.\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e In addition, HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e spectrum line showed that the typical characteristic peak of HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e does not disappear, indicated that the main crystal structure of catalyst is complete before and after TiO\u003csub\u003e2\u003c/sub\u003e loaded.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e3.1.2. FT-IR\u003c/h2\u003e \u003cp\u003eThe FT-IR spectra of HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e and HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e catalysts are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea. As shown in the figure, for HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e, bending vibration and stretching vibration peaks belonging to the H-O-H band adsorbed by water could be observed near 1635cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and between 3320-3500cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e .\u003csup\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/sup\u003e 1404.8 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e showed a band related to -OH groups, which is characteristic of metal oxides.\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e The characteristic peaks in the vicinity of 1086cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 983.5cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e can correspond to the absorption peaks of P-O\u003csub\u003ea\u003c/sub\u003e and W\u0026thinsp;=\u0026thinsp;O\u003csub\u003ed\u003c/sub\u003e of phosphotungstic acid, which are consistent with the literature, \u003csup\u003e[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]\u003c/sup\u003e indicated that phosphotungstic acid has been successfully loaded on SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e. The absorption band of Zr-O-C stretching vibration was observed at 1030 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and two characteristic peaks were observed at 505 and 580 cm-1, both of which belong to Zr-O stretching vibration.\u003csup\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/sup\u003e The observed peak at 670cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e can be attributed to the Sn-O band .\u003csup\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/sup\u003e The peak of Ti-O stretching vibration appears between 450 and 800cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. \u003csup\u003e[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/sup\u003e For HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e, the peak strengthening at 500-800cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e can be observed in the figure, which may be due to the superposition of Ti-O and Zr-O. It indicated that TiO\u003csub\u003e2\u003c/sub\u003e has been successfully doped to HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e \u003cp\u003eIn Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb, the characteristic peaks at 3012, 1650 and 723 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e found in the SBO line are attributed to the stretching vibration of the double bond: C\u0026thinsp;=\u0026thinsp;CH, C\u0026thinsp;=\u0026thinsp;C, cis-CH\u0026thinsp;=\u0026thinsp;CH. After epoxidation, double bonds associated with 3012 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1650 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e bands almost disappeared. This observation is consistent with the research results of Jianghao Wu et al., that the peak strength corresponding to C\u0026thinsp;=\u0026thinsp;CH tensile disappeared after epoxidation.\u003csup\u003e[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]\u003c/sup\u003e The peak intensity of ESBO unsaturated bond signal decreased at 723cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. In addition, the appearance of a new peak at 837 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in the FT-IR spectrum of ESBO was attributed to the epoxy group (C-O-C), which confirmed the successful epoxidation of SBO \u003csup\u003e[\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003e3.1.3. NH\u003csub\u003e3\u003c/sub\u003e-TPD\u003c/h2\u003e \u003cp\u003eThe main desorption peaks of NH\u003csub\u003e3\u003c/sub\u003e in the temperature range of 100\u0026ndash;300℃, 300\u0026ndash;500℃ and 500\u0026ndash;700℃ are related to the weak acid site, moderate acid site and strong acid site respectively. \u003csup\u003e[\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]\u003c/sup\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e showed the NH\u003csub\u003e3\u003c/sub\u003e-TPD analysis results of HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e and HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e catalysts. It could be clearly seen that, with the temperature rose from 50℃ to 800℃, HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e curve has three peaks near 149.5℃, 405℃ and 606.7℃, corresponding to the desorption of NH\u003csub\u003e3\u003c/sub\u003e molecule at weak acid site, moderate acid site and strong acid site, respectively. Among them, desorption peaks at 149.5℃ and 606.7℃ could be attributed to HPW. \u003csup\u003e[\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]\u003c/sup\u003e For HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e curves, there is also a weak acid site near 149.5℃, and a wide peak between 400\u0026ndash;530℃, which corresponds to the moderate acid site, but the strong acid site decreased significantly. The number of acid sites on the surface was calculated by combining the desorption peak area of NH\u003csub\u003e3\u003c/sub\u003e-TPD. HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e (0.75 mmol/g) was higher than HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e (0.60 mmol/g), indicated that the addition of TiO\u003csub\u003e2\u003c/sub\u003e could increase the total acid site of solid acid, but was not conducive to the strong acid site.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003e3.1.4. Py-FTIR\u003c/h2\u003e \u003cp\u003ePyridine-FTIR studies were performed to distinguish the properties of acid sites in catalysts. These peaks are due to the interaction of pyridine with Br\u0026oslash;nsted(B) and Lewis(L) acid sites present on the catalyst surface. Liu et al. \u003csup\u003e[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/sup\u003e found that the parent ZrO\u003csub\u003e2\u003c/sub\u003e was mainly Lewis acid site and the total acid content was low by compared the Py-FTIR of HPW loaded with 0\u0026ndash;15% ZrO\u003csub\u003e2\u003c/sub\u003e. With the increase of HPW loaded, the total acidity of the catalyst increased, especially the Br\u0026oslash;nsted acid.\u003c/p\u003e \u003cp\u003eIt could be observed from Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e that absorption peaks appeared near 1610 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1445 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e with high intensity, and these two peaks are typical characteristic peaks of Lewis acid sites. Among them, 1445 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the characteristic peak of Lewis acid site from Zr \u003csup\u003e4+\u003c/sup\u003e center.\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e A peak of weak Lewis acid sites appeared near 1577 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e,\u003csup\u003e[\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]\u003c/sup\u003e which could be attributed to the skeletal Sn\u003csup\u003e4+\u003c/sup\u003e site. \u003csup\u003e[\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]\u003c/sup\u003e Absorption peaks near 1537\u0026ndash;1550 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1640cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e belong to Br\u0026oslash;nsted acid sites\u003csup\u003e[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]\u003c/sup\u003e, of which 1537\u0026ndash;1550 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the characteristic peak of Br\u0026oslash;nsted acid sites from HPW.\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e The presence of 1640 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e Br\u0026oslash;nsted acid peak in the catalyst could be attributed to the Sn-OH group.\u003csup\u003e[\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]\u003c/sup\u003e The absorption peak near 1490 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e could be attributed to the mixed characteristic peak of Lewis acid site and Br\u0026oslash;nsted acid site.\u003csup\u003e[\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]\u003c/sup\u003e These results indicated that HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e catalyst contains both B and L acid sites .\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section3\"\u003e \u003ch2\u003e3.1.5. SEM\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e showed the SEM images of HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e and HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e respectively. The image of HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea and b) reflected the catalyst is an irregular block with rough edges. There were small block SnO\u003csub\u003e2\u003c/sub\u003e and fine powder particles HPW evenly dispersed on the surface, and there are pores of different sizes between the particles. The image of HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ec and d) displayed that many new near-spherical particles were added on the irregular block surface of HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e. These near-spherical particles are TiO\u003csub\u003e2\u003c/sub\u003e, indicated that TiO\u003csub\u003e2\u003c/sub\u003e has been successfully and uniformly loaded on HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e. EDS results (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ee) showed that the elements Sn, W and Ti were evenly distributed in the catalyst. This result supported the assumption from XRD results that HPW and SnO\u003csub\u003e2\u003c/sub\u003e are uniformly dispersed on the surface of the catalyst.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003e3.1.6. Nitrogen-adsorption-desorption\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e showed the nitrogen adsorption isotherms of HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e and HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e. As can be seen from the figure, both samples exhibited Ⅳ-type adsorption isotherm, which are typical characteristics of mesoporous materials according to IUPAC classification. The isotherms of HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e show an H2-type hysteresis loop, indicated a uniform pore size distribution for this sample. With the addition of TiO\u003csub\u003e2\u003c/sub\u003e, its isotherm showed an H3-type hysteresis loop, indicated that the pore structure of this catalyst became irregular after the addition of TiO\u003csub\u003e2\u003c/sub\u003e.The pore size distributions image of the HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e and HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e catalyst were calculated showed in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e based on the desorption branch of the isotherms using the BJH method. The image showed that all samples had pore size distribution within the mesopore range approximately 9 nm to 16 nm. This also verified the pore structure seen in SEM images. The specific surface area of HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e was slightly higher than that of HPW/SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e (63.1007m\u003csup\u003e2\u003c/sup\u003e/g vs 46.02142m\u003csup\u003e2\u003c/sup\u003e/g), indicated that the addition of TiO\u003csub\u003e2\u003c/sub\u003e was beneficial to increase the specific surface area of solid acid.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section3\"\u003e \u003ch2\u003e3.1.7. XPS\u003c/h2\u003e \u003cp\u003eThe XPS diagrams of HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e are showed in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, and the full XPS spectrum of the catalyst indicated the presence of C, W, Ti, Sn and Zr elements(Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea). Signal peaks at 284.9 eV in the C 1s XPS diagram(Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eb) was attributed to C-C bonds. W 4f XPS diagram in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ec exhibited double peaks at 34.1 eV and 35.9 eV of the W 4f 7/2 and W 4f 5/2 assigned to intact HPW. This indicated that the phosphotungstic acid was successfully introduced to the HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e sample.\u003csup\u003e[\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]\u003c/sup\u003e Ti 2p XPS diagram in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ed exhibited double peaks located at 459.3 eV and 464.9 eV, related to Ti 2p3/2 and Ti 2p1/2 signals of Ti (IV) species, respectively.\u003csup\u003e[\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]\u003c/sup\u003e The peak of 487.5 eV in Sn 3d XPS(Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ee) was devied from the SnO\u003csub\u003e2\u003c/sub\u003e.\u003csup\u003e[\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]\u003c/sup\u003e Zr 3d XPS diagram in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ef exhibited double peaks at 183.1 eV and 185.5 eV, which were attributed to Zr 3d3/2 and Zr 3d5/2, respectively.\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e XPS spectra showed that HPW, TiO\u003csub\u003e2\u003c/sub\u003e, SnO\u003csub\u003e2\u003c/sub\u003e and ZrO\u003csub\u003e2\u003c/sub\u003e exist in the catalyst.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section3\"\u003e \u003ch2\u003e3.1.8. TG\u003c/h2\u003e \u003cp\u003eThe percentage weight loss of the catalyst is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e. Thermal degradation of solid acid catalyst was observed with increasing temperature, that is, the sample weight decreased slowly with increasing temperature. The first mass loss is below 100℃, and a sharp endothermic peak could be observed from the DTG curve near 25\u0026ndash;100℃, indicated that the mass of catalyst droped rapidly at this position, and the weight loss in this part is mainly due to the removal of adsorptive water and air.\u003csup\u003e[\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e]\u003c/sup\u003e The gradual weight loss of the catalyst at 100\u0026ndash;800℃ could be attributed to the gradual decomposition of HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e. Among them, mass loss after 400℃ is related to the decomposition of Keggin structure of phosphotungstic acid. \u003csup\u003e[\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]\u003c/sup\u003e In conclusion, the total mass loss of the sample is only 5.28% in the range of 25\u0026ndash;800℃, indicated that HPW/ TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e catalyst has good thermal stability at higher temperature. In this study, all reaction temperatures were below 100℃, so the catalyst met the temperature requirements for the epoxidation.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Catalytic activity\u003c/h2\u003e \u003cdiv id=\"Sec19\" class=\"Section3\"\u003e \u003ch2\u003e3.2.1. Effect of catalyst dosage\u003c/h2\u003e \u003cp\u003eThe function of the catalyst is to catalyze H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e and formic acid to form peroxyformic acid, and then peroxyformic acid as an epoxidation reagent to form epoxy bonds in soybean oil. Soybean oil was used as raw material, HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e was used as catalyst, under the conditions of n (double bond) : n (hydrogen peroxide) : n (formic acid)\u0026thinsp;=\u0026thinsp;1 : 2.4 : 1.2 and reaction temperature of 55℃, the influence of catalyst dosage (measured by soybean oil quality) on the epoxidation reaction was investigated, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e. At the initial stage of the reaction, the reaction speed was fast, and the conversion rate showed an increasing trend. The relative conversion rate of oxirane increased with the increase of the dosage of catalyst. When the dosage of catalyst was 1wt%, the RCO reached 83.15% at 3h. It indicated that increased the amount of catalyst could increased the concentration of active ingredients and speeded up the reaction. \u003csup\u003e[\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e]\u003c/sup\u003e Although the conversion rate was basically the same at 2.5h and 3h when the amount of catalyst was 0.5wt% and 1wt%, the conversion rate was higher in the first 2h when the amount of catalyst was 1wt%, indicated that the dosage of 1wt% could achieve better epoxidation effect in a relatively short time. In addition, further increased of catalyst dosage could easily pile up in the reaction system and reduced the contact between the active site and the reactants, led to the reduction of conversion rate.\u003csup\u003e[\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e]\u003c/sup\u003e Therefore, considered the catalytic effect and economic benefit, 1wt% catalyst dosage is the most appropriate.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section3\"\u003e \u003ch2\u003e3.2.2. Effect of formic acid dosage\u003c/h2\u003e \u003cp\u003eIn the preparation reaction of ESBO, formic acid acts as an oxygen carrier, reacts with H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e to generate peroxyformic acid, and then reacts with unsaturated groups in SBO molecular structure to generate ESBO.\u003csup\u003e[\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e]\u003c/sup\u003e Under the conditions of n (double bond) : n (H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e)\u0026thinsp;=\u0026thinsp;1 : 2.4, catalyst dosage 1wt% and reaction temperature 55℃. The influence of formic acid dosage on RCO was investigated, and the results are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e. When the dosage of formic acid was increased from n (double bond): n (formic acid)\u0026thinsp;=\u0026thinsp;1 : 0.9 to 1 : 1.8, the RCO increased rapidly from 68.65\u0026ndash;82.46% at 2 h, while when the dosage of formic acid was further increased to 1: 2.1, the conversion rate of ESBO decreased to 80.39%. It indicated that appropriately increased the dosage of formic acid could increased the concentration of intermediate peroxyformic acid and promoted the generation of ethylene oxide group, thus improved RCO.\u003csup\u003e[\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e]\u003c/sup\u003e However, formic acid itself has certain acidity and strong reactivity. Therefore, excessive increased in the dosage of formic acid will lead to the instability of oxirane ring and accelerated the ring-opening side reaction between ESBO epoxy group and water, thus reducing the RCO value. \u003csup\u003e[\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section3\"\u003e \u003ch2\u003e3.2.3. Effect of fydrogen peroxide dosage\u003c/h2\u003e \u003cp\u003eAs can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e, with the increased of n (double bond): n (H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e) mole ratio, the conversion rate first increased and then decreased. The optimal n (double bond):n (H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e) mole ratio was 1: 3.2, which made the soybean oil conversion rate the highest, reached 85.08%. The reason may be that the increased in the dosage of hydrogen peroxide promoted the production of performic acid, which in turn promoted the formation of oxirane rings. \u003csup\u003e[\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e]\u003c/sup\u003e Too little or too much H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e will affect the effect of epoxidation. Because too little H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e will generate less peroxyformic acid, resulted in incomplete epoxidation reaction. However, excessive H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e is also not conducive to the generation of epoxy products. Although the reaction speed of epoxidation is accelerated, it will also accelerated the side reaction in the epoxidation reaction process, led to the ring-opening of epoxy bonds.\u003csup\u003e[\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e]\u003c/sup\u003e Moreover, the increase of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e will reduced the acid activity in the water phase, thus reduced the overall activity of the catalyst, led to the reduction of the epoxidation efficiency. \u003csup\u003e[\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section3\"\u003e \u003ch2\u003e3.2.4. Effect of reaction temperatrue\u003c/h2\u003e \u003cp\u003eAs can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e that the RCO is low when the reaction is carried out at 45℃. With the increase of reaction temperature, the reaction speed became faster. When the reaction temperature rose to 55℃, the conversion rate increased significantly, reached 85.08% at 2h, because higher epoxidation reaction temperature is conducive to the formation of peroxyformic acid, which leaded to a faster epoxidation rate.\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e However, as the reaction temperature continued to rise and the epoxidation speed increased, side reactions such as ring-opening were prone to occur, resulted in a trend of RCO value decline. This may be due to the decomposition of the resulted epoxides at higher reaction temperatures, thus formed more by-products, that is, the epoxide products in acidic systems are unstable at high reaction temperatures. \u003csup\u003e[\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]\u003c/sup\u003e So Under the conditions of n (double bond) : n (H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e) : n (HCOOH)\u0026thinsp;=\u0026thinsp;1 : 3.2 : 1.8 and catalyst dosage of 1wt%, the reaction temperature of 55℃ is suitable, the reaction speed is fast, and the conversion rate is the highest, which is 85.08%.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section2\"\u003e \u003ch2\u003e3.3. Comparison of hydrodynamic cavitation (HC) and mechanical stirring (MS)\u003c/h2\u003e \u003cp\u003eUnder the conditions of n(C\u0026thinsp;=\u0026thinsp;C): n (H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e): n(HCOOH)\u0026thinsp;=\u0026thinsp;1:3.2:1.8, the dosage of catalyst is 1wt%, and the temperature is 55℃, the advantages of solid acid catalysis are studied compared with without catalyst. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003e, used the conventional mechanical stirring method at 300 r/min, the rate of epoxidation was slow and the RCO value did not reach 70% at 3h of reaction. It may be due to the fact that the mechanical stirring method is mainly based on the cutting force provided by the blade rotation to achieve the two-phase mixing, which is less effective in mass transfer between reactants and can cause dead zones on the stirred tank walls.\u003csup\u003e[\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e]\u003c/sup\u003e The collapse of the cavitation-generated vacuoles could impact the two-phase interface, increase the contact opportunities between the reacting substances, accelerate the renewal of the phase surface and enhance the effect of mass transfer. In the study, the conversion rate could reach 79.97% at 3h when only hydrodynamic cavitation was used without the addition of catalyst, which also proved that hydrodynamic cavitation could accelerate the rate of epoxidation reaction and increased the epoxy value of the product. The relative conversion of oxirane of soybean oil could reach 85.08% in 2h when solid acid catalyzed epoxidation was enhanced by hydrodynamic cavitation technology, which shortened the reaction time and improved the epoxidation efficiency at the same time, due to the fact that hydrodynamic cavitation technology not only promoted the mixing between reactants, but also continuously refreshed the catalyst surface by generated micro-jets and shock waves, and prevented the catalyst particles from aggregating, thus increasing the effective surface area of the catalyst to improve the overall reaction efficiency.\u003csup\u003e[\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec24\" class=\"Section2\"\u003e \u003ch2\u003e3.4. Reusability of HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e\u003c/h2\u003e \u003cp\u003eThe reusability of the catalyst is a critical factor catalysts in the epoxidation. Used soybean oil as raw material, HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e as catalyst, n (C\u0026thinsp;=\u0026thinsp;C) : n (H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e) : n(HCOOH)\u0026thinsp;=\u0026thinsp;1:2.4:1.2, and the reaction temperature was 55℃, the reusability of the catalyst was investigated. At the end of each experiment, the catalyst was cleaned with methanol and distilled water to remove the adsorbed reactants on the surface of the catalyst. After dryed at 105℃ for 5h, the catalyst was transferred to muffle furnace for calcined at 500℃ for 3 h, and then applied to the next experiment. The experimental results are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003e. The RCO of soybean oil at 3h of epoxidation reaction decreased slightly from 83.15\u0026ndash;80.52% after five consecutive cycles, and only decreased by 2.59%. Therefore, the catalyst showed excellent stability and good repeatability. In addition, FT-IR images (Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003eb) of catalysts before and after use were compared, and the infrared images of the catalysts after calcined at 500℃ for 3h were basically the same as those before use, indicated that wash and calcination can remove the adsorbed organic part in the reaction process,\u003csup\u003e[\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e]\u003c/sup\u003e which indicated that the structure of catalysts was stable. According to the SEM figure (Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003ec and d), the morphological structure and porous characteristics of the solid acid catalyst remain unchanged, which is an important reason why the catalyst still maintains good activity after 5 cycles.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThis work highlights the enhanced epoxidation of soybean oil catalyzed by HPW/TiO\u003csub\u003e2\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e-ZrO\u003csub\u003e2\u003c/sub\u003e used hydrodynamic cavitation and optimizes the effects of various process parameters. The optimized parameters were as follows: catalyst dosage is 1wt%, n(C\u0026thinsp;=\u0026thinsp;C): n(HCOOH)\u0026thinsp;=\u0026thinsp;1:1.8, n(C\u0026thinsp;=\u0026thinsp;C):n(H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e)\u0026thinsp;=\u0026thinsp;1:3.2, temperature 55 ℃. Under these optimized conditions, the highest relative conversion of oxirane of 85.08% was found for 2h of reaction under hydrocavitation-enhanced solid acid catalysis. In contrast, the epoxidation reaction without the addition of catalyst or used the conventional mechanical stirring method could not achieve an RCO value of 80% even after 3 h of reaction. In addition, it was observed that the catalyst was heterogeneous and stable, and the epoxidation effect did not decrease significantly after repeated used for 5 times. The results indicated that the catalyst can be used to catalyze the epoxidation of soybean oil and improve the epoxidation efficiency effectively.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCRediT authorship contribution statement\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSimin Mo:\u003c/strong\u003e Data curation, Formal analysis, Methodology, Visualization, Writing-original draft. \u003cstrong\u003eQianwei Cheng:\u003c/strong\u003e Supervision, Resources, Funding acquisition, Project administration. \u003cstrong\u003eXiaoli Wei:\u0026nbsp;\u003c/strong\u003eConceptualization, Formal analysis. \u003cstrong\u003eTong Chen:\u0026nbsp;\u003c/strong\u003eSupervision, Formal analysis.\u003cstrong\u003e\u0026nbsp;Luli Meng:\u003c/strong\u003e Conceptualization, Formal analysis, Visualization. \u003cstrong\u003eGao Ming:\u0026nbsp;\u003c/strong\u003eFormal analysis,Visualization. \u003cstrong\u003eKena Yu:\u003c/strong\u003eVisualization.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;This work was supported by\u0026nbsp;the Guangxi Natural Science Foundation Project\u0026nbsp;[2020GXNSFAA159101].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data used in this study are available upon request from the corresponding author.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eMJ Jalil, IS Azmi, A Hadi, AFM Yamin, Journal of Polymer Research 29, 2022). http://dx.doi.org/10.1007/s10965-022-02944-4\u003c/li\u003e\n\u003cli\u003ePT Wai, PP 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http://dx.doi.org/10.1016/j.cej.2017.01.011\u003c/li\u003e\n\u003cli\u003eD Zhao, T Su, D Rodr\u0026iacute;guez-Padr\u0026oacute;n, H L\u0026uuml;, C Len, R Luque, Z Yang, Materials Today Chemistry 24, 100745(2022). http://dx.doi.org/10.1016/j.mtchem.2021.100745\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-porous-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jopo","sideBox":"Learn more about [Journal of Porous Materials](http://link.springer.com/journal/10934)","snPcode":"10934","submissionUrl":"https://submission.nature.com/new-submission/10934/3","title":"Journal of Porous Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"soybean oil, epoxidation, solid acid catalyst, hydrodynamic cavitation","lastPublishedDoi":"10.21203/rs.3.rs-2651546/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-2651546/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBACKGROUND\u003c/h2\u003e\n\u003cp\u003eEpoxidized vegetable oils are widely used as plasticizers, lubricants and reaction intermediates. In this work, a new solid acid catalyst was developed to obtain epoxidized soybean oil in high yield and combined with hydrodynamic cavitation technology to improve the efficiency of epoxidation. The structure and morphology characteristics of the catalyst were studied by XRD, FT-IR, Py-FTIR, NH\u003csub\u003e3\u003c/sub\u003e-TPD, SEM, N\u003csub\u003e2\u003c/sub\u003e-adsorption and desorption analysis and TG techniques. It was applied to the epoxidation of soybean oil, and the influence of various parameters including catalyst dosage, formic acid dosage, hydrogen peroxide dosage and reaction temperature on the relative conversion rate of oxirane of soybean oil, as well as the recyclability of catalyst was studied.\u003c/p\u003e\n\u003ch2\u003eRESULTS\u003c/h2\u003e\n\u003cp\u003eThe catalyst has both Lewis and Brönsted acid sites and is stable at high temperatures. Under the optimum reaction conditions, the relative conversion rate of oxirane was 85.08% at 2h. The catalytic activity did not decrease significantly after 5 cycles of the reaction.\u003c/p\u003e\n\u003ch2\u003eCONCLUSION\u003c/h2\u003e\n\u003cp\u003eThe results show that the catalyst is easy to prepare, has good catalytic activity in catalyzing the epoxidation reaction of soybean oil, and is easy to recover and highly reusable.\u003c/p\u003e","manuscriptTitle":"Investigation of HPW/TiO 2 -SnO 2 -ZrO 2 catalytic performance for epoxidation of soybean oil under hydrodynamic cavitation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-03-13 22:42:10","doi":"10.21203/rs.3.rs-2651546/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major revision","date":"2023-04-02T15:35:40+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2023-03-16T02:25:26+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"c65855f6-d2a6-408c-b1bc-321080a46f17","date":"2023-03-10T22:53:23+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2023-03-10T21:18:25+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2023-03-06T12:03:56+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2023-03-06T12:03:56+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Porous Materials","date":"2023-03-03T12:41:13+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-porous-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jopo","sideBox":"Learn more about [Journal of Porous Materials](http://link.springer.com/journal/10934)","snPcode":"10934","submissionUrl":"https://submission.nature.com/new-submission/10934/3","title":"Journal of Porous Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"e9b295d3-dac5-40be-a638-0a2188414e1f","owner":[],"postedDate":"March 13th, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2023-10-16T20:51:40+00:00","versionOfRecord":{"articleIdentity":"rs-2651546","link":"https://doi.org/10.1007/s10934-023-01466-8","journal":{"identity":"journal-of-porous-materials","isVorOnly":false,"title":"Journal of Porous Materials"},"publishedOn":"2023-05-05 20:42:12","publishedOnDateReadable":"May 5th, 2023"},"versionCreatedAt":"2023-03-13 22:42:10","video":"","vorDoi":"10.1007/s10934-023-01466-8","vorDoiUrl":"https://doi.org/10.1007/s10934-023-01466-8","workflowStages":[]},"version":"v1","identity":"rs-2651546","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-2651546","identity":"rs-2651546","version":["v1"]},"buildId":"cBFmMYwuxLRRLfASyISRj","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}