Synthesis Of Hierarchical Titanium Silicalite-1and Catalytic Performances In Cyclohexanone Ammoximation Reaction

Titanium silicalite-1(TS-1) shows great catalytic activities in many reactions,such as the hydroxylation of phenols, epoxidation of alkenes, and ammoximation ofketones. The system of TS-1and H2O2exhibits excellent catalytic oxidationperformances in mild reaction conditions and has been paid more attentions by theresearchers in both domestic and aboard. However, the small pores of TS-1zeoliteslimits its catalytic activity and imposes mass transport limitation.In this paper, we introduced mesopores and macropores into the TS-1zeolitecrystals by using nanosized carbon black powders as hard templates and performingthe TPAOH post treatment. Then several methods were used to characterize thehierarchical TS-1zeolites, such as FT-IR, UV-vis, XRD, BET, SEM and TEM. Thecatalytic activity of these hierarchical TS-1zeolites were also evaluated and comparedin the reaction of cyclohexanone ammoximation.Firstly, several details in the hydrothermal synthesis of TS-1were studied. Theexperiments in this part studied the influences of H2O/SiO2, crystallizationtemperature and adding amount of Ti sources. The catalytic activities of microporousTS-1zeolites were evaluated in the reaction of cyclohexanone ammoximation.In the second part, mesoporous TS-1zeolites were synthesized by adding carbonblack particles during the hydrothermal synthesis process. The influences of theadding of carbon black on relative crystallinity, feature of pore structure, Ti content inthe framework of TS-1and their catalytic performances in cyclohexanoneammoximation were also studied.In the third part, we deployed the TPAOH post treatment process on themesoporous TS-1as synthesized above. Several hierarchical TS-1zeolite weresynthesized, which possessed marcopores and micropores in the crystal. The catalyticperformances of these hierarchical TS-1zeolites were evaluated and compared in thereaction of cyclohexanone ammoximation.