Improving the performance of TS-1 catalysts for continuous cyclohexanone ammoximation through controlment of active species distribution

Abstract

The active species distribution of zeolites significantly influences the catalytic performance. In this paper, titanium silicalite-1 (TS-1) was synthesized from silica sol, TiCl₃ and NH₃ with tetrapropyl ammonium bromide (TPAB) as the template agent. Modification with ethanolamine altered the distribution of Ti species in TS-1 particles. Some large voids as 50 × 70 nm and 70 × 110 nm existed in the inner part of modified TS-1 crystals and were responsible for improved diffusion properties and accessibility to active sites. The modified TS-1 was examined in continuous cyclohexanone ammoximation. A high conversion of cyclohexanone (98%) and oxime selectivity (100%) was still maintained after the test reaction had been carried out up to 410 h. The modified TS-1 is able to serve as a stable catalyst for continuous cyclohexanone ammoximation.