Synthesis Of ZSM-5 Zeolite Catalysts From Leached Illite Clay

ZSM-5 is one kind of zeolite with unique microporous structure.One is a straight channel with an aperture of 0.53×0.56 nm,and the other is a "zigzag" channel with an aperture of 0.51×0.55 nm.These intersections are perpendicular to each other,creating a three-dimensional framework.Compared with other zeolites,ZSM-5 has the advantages of high activity and low deactivation,so it is widely used in industrial production.In the second chapter,the ZSM-5 zeolite was synthesized hydrothermally by seed-assited method with silica sol as the silicon source and with the aid of glycerin,amino sugar,glucose,chitosan,starch and other natural organic molecules.The synthesis of zeolites by seed-assited method requires a certain amount of Na+cations.Na+ can play a guiding role in structure,but can promote the formation of quartz impurities in the zeolite.The addition of glycerin can inhibit the formation of quartz impurities,and can improve the crystallinity of the zeolite,control the grain size and increase the acid sites.Meanwhile,the synthesized ZSM-5 zeolite exhibited high catalytic activity in toluene disproportionation.The results showed that the addition of amino sugar and chitosan promoted the growth of the ZSM-5 zeolite,while the addition of glucose inhibited the growth of the ZSM-5 zeolite,and the addition of starch maximized the catalytic activity of the ZSM-5 zeolite.In the third chapter,a seed induced rapid synthesis of submicron ZSM-5 zeolites from leached illite clay has been achieved through solid-like state conversion.The optimum synthesis conditions and crystallization mechanism were also studied.The results demonstrated that well-dispersed submicron-sized ZSM-5 zeolites were synthesized in a relatively short time(6 h).In the solid-like state conversion synthesis system induced by the seed crystal,the sample gradually transformed from amorphous to well-dispersed submicron ZSM-5 zeolite as the crystallization time increased.At the same time,the aluminum in the zeolite framework can provide an acidic site.The catalytic results of synthetic ZSM-5 zeolite in toluene disproportionation reaction under optimal formulation were as follows:toluene conversion and p-xylene selectivity were 30.5%and 21.5%,respectively.The toluene conversion rate was higher than that of the industrial ZSM-5 zeolite,while the conversion rate of 1,2,4-trimethylbenzene and the selectivity of p-xylene are close to that of the industrial ZSM-5 zeolite.In the fourth chapter,acid-leached illite silica residues was used as silicon source(no quartz impurity peak),TPAOH was used as the organic template,ZSM-5 zeolite was synthesized by SAC method at low temperature,and low temperature synthesis of zeolite zeolite reduced energy and avoided the dangers of high temperature synthesis.The effects of various synthetic factors were investigated and the following conclusions were reached:the minimum temperature required for the synthesis of ZSM-5 zeolite was 70?.At different temperatures,the zeolites synthesized by different SiO2/Al2O3 ratios were spherical.As the SiO2/Al2O3 ratio increased,the grain size of the zeolites decreased first and then increased,and the dispersion decreased.In the toluene disproportionation reaction,the toluene conversion rate of the synthesized sample was 5 points lower than that of the seed.The selectivity of the synthetic sample is similar to that of industrial zeolites.