Catalytic Performance Of Alkene Epoxidation Over Monolithic TS-1

TS-1 nanoparticles were synthesized by hydrothermal method with tetrapropyl ammonium hydroxide?TPAOH?as the template.Various monolithic catalysts were prepared by extrusion molding and secondary coating methods.The catalyst was used in the epoxidation of olefin in a fixed bed reactor.The preparation method and the effect of catalyst properties on the catalytic performance were studied.The main results obtained are as follows:From the point of view of catalyst filling and separation,the extruded monolithic TS-1catalyst with special morphology was prepared by special extrusion molding.The stability of the catalyst is similar to that of the conventional extruded catalyst,but the initial conversion of H₂O₂ is relatively low,which may be due to the large pore size of the catalyst,leading to the insufficient contact between the reactant and the catalyst.From the point of view of enhancing the heat transfer performance of the catalyst itself,the monolithic TS-1 catalyst was prepared by loading TS-1 on the monolithic stainless steel support by the secondary coating method.Compared with conventional extruded TS-1 catalysts,the monolithic catalysts prepared on stainless steel have little difference in the performance of propylene epoxidation,but show better catalytic performance in 1-butene epoxidation.This is mainly attributed to the higher heat transfer rate of the latter,which can inhibit the occurrence of the ring-opening side reactions of epoxy-butane and improve the stability of the catalyst.Moreover,the monolithic TS-1 catalyst has excellent reusable performance.The catalytic performance of stainless steel monolithic TS-1 catalyst with different pore sizes shows obvious difference.The catalytic performance of TS-1/MSS-1 with 20 mesh size is the best,the catalytic performance of TS-1/MSS with 40 mesh size is relatively poor,and the conversion rate of H₂O₂ of TS-1/MSS-1 with 10 mesh size is relatively low because of the existence of macroporous channel.Using nickel based foam metal as the carrier to prepare the monolithic TS-1 catalyst by the secondary coating method,the active component of TS-1 was seriously lost during the epoxidation of propylene,and the foam metal skeleton was partially dissolved.