Effect on the introduction of hollow structure on Au/TS-1 to improve the stability for propylene epoxidation

Abstract

In the direct gas-phase epoxidation of propylene, the channels of TS-1 are easily blocked by the carbon deposition which leads to poor stability and even deactivation of the catalyst. In this paper, H-TS-1 molecular sieve with hollow structure was successfully synthesized by the post-treatment of TS-1 molecular sieve with tetrapropylammonium hydroxide (TPAOH) solution. The experimental results show that the Au/H-TS-1 catalyst exhibits good stability compared with Au/TS-1. TG results show that the weight of carbon deposition is only ∼3.56 wt% in Au/H-TS-1 at the reaction time of 50 h compared with Au/TS-1 catalyst (∼8.55 wt%). The introduction of hollow structure improves the mass transfer ability of the catalyst which could reduce the formation of carbon deposition and improve the stability of Au/H-TS-1 in propylene epoxidation. The PO formation rate of Au/H-TS-1 only decreased by ∼10.3 % after 100 h, while that of Au/TS-1 decreased by ∼28.3 %.