Study On Preparation And Catalytic Properties Of TS-1Monolithic Catalyst

Titanium silicalite-1(TS-1) molecular sieve, as one kind of environmentally friendly catalysts, has excellent catalytic-oxidation performance in H2O2/TS-1system with mild reaction conditions in many organic reactions and can overcome the inevitable disadvantages in traditional processes, such as serious pollution, harsh reaction conditions and complicated operation et al. This application, however, has been hindered by quick inactivity of TS-1catalyst and difficulty in separation because of too fine TS-1zeolite particles on industrial projects.This paper investigated the preparation of TS-1films on monolithic honeycomb cordierite supports using dip-coating and hydrothermal crystallization growth. The factors of preparation of TS-1monolithic, such as pre-treatment of cordierite supports, thickness of TS-1film coated, number of dip-coating or crystallization growth, were analyzed by experiment. And the stability and catalytic ammoximation reaction activity of TS-1film immobilized by dip-coating and hydrothermal crystallization were investigated by experiment. TS-1film immobilized on cordierite support were characterized by FT-IR, Uv-vis, SEM and TEM, while mechanism of hydrothermal crystallization TS-1film on cordierite support were researched.The experimental results indicate that the stability of TS-1film immobilized on cordierite support had been relevant to pre-treatment of support and thickness of TS-1film. The results showed that TS-1film immobilized by dip-coating on the cordierite support treated with1N HNO3had more stability than with silicon sol or sodium silicate, and TS-1film immobilized by hydrothermal crystallization controlling the growth of TS-1crystal had most stability. And the stability of TS-1film immobilized on cordierite support had negative correlation with thickness of TS-1film.Cyclohexanone ammoximation was taken as a model reaction to evaluate the catalysis of TS-1catalyst powder crystallized by hydrothermal synthesis in batch reactor and TS-1monolithic catalysts prepared by dip-coating (TS-1powder provided by Baling SINOPEC) or hydrothermal synthesis crystallization in the homemade external loop reactor system. The relationship of the morphology and size of TS-1catalyst with catalytic activity in cyclohexanone ammoximation and the effect of space velocity based catalyst weight hourly space velocity (WHSV) and thickness of TS-1film immobilized on codierite support were investigated in detail by exeperiment.When the morphology of homemade TS-1was like blackberry and the size of TS-1particle was less than300nm, the excellent catalystic activity was showed in cyclohexanone ammoximation reaction. The results of continuous ammoximation reaction on TS-1 monolithic catalyst prepared by hydrothermal synthesis crystallization in an external looped monolithic reactor at343K, with external circulation260ml/min, displayed that more than90%in conversion of cyclohexanone and over99%in yield and selectivity of cyclohexanone oxime, respectively. TS-1monolithic catalyst began deactivation after120hours. At the same operation conditions, the TS-1monolithic catalyst prepared by dip-coating (TS-1powder provided by Baling SINOPEC) showed more excellent catalytic activities than that by hydrothermal synthesis crystallization.The conversion of cyclohexanone, selectivity of cyclohexanone oxime and the life of TS-1monolithic during cyclohexanone ammoximation reaction decreased with space velocity. The more thickness of TS-1film may increase resistance of internal mass transfer, product more carbon deposits, and shorten the life of TS-1catalyst, and decrease the catalytic activity. That could be decribed by ratio of carbon deposition η, which can provide valuable insight into the elucidation of optimum reaction.