Synthesis Of Zn-modified TS-1 Zeolite Catalyst And Its Catalytic Epoxidation Of Soybean Oil

This research is based on the good catalytic oxidation performance of titanium silicon（TS-1）zeolite,with the strategy of surface metal modification and catalyst structure adjustment,by modifying the solid TS-1 catalyst with supported metals,a series of high-performance metals have been prepared.The supported heterogeneous catalyst is used in the epoxidation reaction of SO to study the catalyst performance and reaction kinetics.First,using various advanced characterization techniques for performing detailed and systematic characterization and correct analysis of the microstructure of the catalyst（surface morphology,composition,structure and surface properties,etc.）;secondly,the characterization results of the catalyst were correlated with the activity test data to study the influence law of SO epoxidation over TS-1 based catalysts,and the mechanism of the epoxidation reaction is further clarified and revealed;finally,the reaction conditions of SO epoxidation to produce ESO were optimized through single factor experiment,and the better production technology of ESO was obtained.The specific research contents were as follows:（1）Based on the preliminary research of this research group on TS-1 catalyzed SO epoxidation reaction,TS-1 zeolite was positively modified to improve its catalytic performance.A series of TS-1 supported Zn（xZn/TS-1）catalysts were synthesized by using an equal volume impregnation method to load metallic zinc（Zn）on TS-1 zeolite with using TS-1 as a carrier,and test its performance on the reaction of SO epoxidation to produce ESO.The results show that Zn/TS-1 has higher catalytic activity than TS-1 with combining with various characterization information of the catalyst,and the morphology and framework structure of TS-1 were not changed after TS-1 was loaded with zinc,but the coordination environment of the framework titanium has changed significantly,which was attributed to the weakening of the bonding effect of the introduced Zn species on the Ti-O bond.With the single factor method,the optimal process conditions for obtaining xZn/TS-1 catalyzed SO epoxidation:xZn/TS-1 loaded with 2%Zn,the reaction time was12 h,H₂O₂:C=C（SO）=2.4:1（molar ratio）,the amount of catalyst was 0.1 g,the reaction temperature was 80°C and the stirring speed was 550 rpm.However,the stability（reusability）of the catalyst was poor.After the catalyst was recycled 4 times,the SO conversion was reduced from 38.33%to 24.4%.This was due to the weak polarity of the catalyst surface and the strong adsorption of small-polar SO molecules during the reaction process,which maked it difficult for SO molecules to desorb on the surface,and large-size SO molecules easily blocked the microporous channels of the TS-1 catalyst.（2）Study on the intrinsic kinetic behavior of xZn/TS-1 catalyzed SO epoxidation reaction.Firstly,the influence of various reaction factors（metal Zn loading,reaction temperature,stirring speed,H₂O₂ to C=C（SO）molar ratio,reaction time）on the reaction performance were investigate;then the kinetic model of xZn/TS-1 and TS-1 catalyzed SO epoxidation reaction was established,respectively.By calculating and fitting the experimental data obtained in the reaction,the activation energies of the reaction catalyzed by corresponding catalyst were about 97.02 k J mol^-1 and 101.47 k J mol^-1,respectively.And the related data such as the kinetic equation was obtained,so as to obtain a guide for the design of industrial reactors for SO epoxidation.Meanwhile,the related information also laid a good foundation for the industrialization of xZn/TS-1 catalyzed SO epoxidation reaction.（3）On the basis of the Zn/TS-1 catalyst,in order to develop a higher performance TS-1 based catalyst,the equal volume impregnation method was adopted to load the metallic Zinc（Zn）and cadmium（Cd）on the TS-1 zeolite.The xCd-y Zn/TS-1 catalyst was synthesized and tested for its performance in catalyzing the epoxidation of SO to produce ESO.Combined with the characterization data of XRD,FT-IR,UV-vis,SEM,TEM,Mapping,ICP and XPS,the results showed that the catalytic performance of the bimetallic catalyst was further improved compared to the Zn/TS-1 catalyst.Similarly,TS-1 loaded with zinc and cadmium still did not change the morphology and framework structure of TS-1,but the coordination environment of the framework titanium of the catalyst changed significantly,which was attributed to the weakening of the bonding effect of the introduced Zn and Cd species on the Ti-O bond.Finally,the single factor method was used to obtain the optimal process conditions for xCd-y Zn/TS-1 catalyzed SO epoxidation:xCd-y Zn/TS-1loaded with 0.5%Cd-2%Zn,reaction time was 12 h,H₂O₂:C=C（SO）=2.4:1（molar ratio）,the amount of catalyst was 2 wt%,the reaction temperature was 80°C and the stirring speed was 550 rpm.