A novel titanosilicate with MWW structure: Highly effective liquid-phase ammoximation of cyclohexanone

The liquid-phase ammoximation of cyclohexanone with ammonia and hydrogen peroxide was conducted over Ti-MWW. Ti-MWW is capable of giving both cyclohexanone conversion and oxime selectivity >99% under optimum reaction conditions. It is a highly active, selective, and reusable catalyst for the synthesis of cyclohexanone oxime in the presence of water. In comparison to other titanosilicates, Ti-MWW shows much higher catalytic activity, even superior to that of TS-1. The catalytic performance of Ti-MWW depends greatly on the operating conditions of the reaction, especially the method of adding substrates. The reason why the method of adding substrates plays such an important role in the ammoximation of ketones or aldehydes over Ti-MWW was investigated after a detailed evaluation of the reaction mechanism.