An investigation into cyclohexanone ammoximation over Ti-MWW in a continuous slurry reactor

In the present study, the liquid-phase ammoximation of cyclohexanone with ammonia and hydrogen peroxide was studied using a MWW-type titanosilicate (Ti-MWW) catalyst in a continuous slurry reactor to develop a clean process for producing cyclohexanone oxime. The reaction parameters, which governed the cyclohexanone conversion, oxime selectivity and catalyst deactivation, were investigated by simulating the operating conditions of an industrial process. Under optimized reaction conditions, Ti-MWW produced a cyclohexanone conversion and oxime selectivity over 96% and 99%, respectively. Moreover, Ti-MWW was extremely robust and showed a longer lifetime than the conventional titanium silicalite-1 catalyst. The causes of deactivation were elucidated to be the coke deposition and partial dissolution of the zeolite framework of Ti-MWW during ammoximation. The deactivated Ti-MWW catalyst was regenerated effectively by a combination of acid treatment and cyclic amine-assisted structural rearrangement.