Mesoporous silica FSM-16 catalysts modified with various oxides for the vapor-phase Beckmann rearrangement of cyclohexanone oxime Original Research Article

Mesoporous silica FSM-16 catalysts modified with various oxides have been prepared, subjected to measurement of acid–base properties, and applied as a catalyst to the vapor-phase Beckmann rearrangement of cyclohexanone oxime. Acid–base properties of the catalysts were measured by the basic indicator adsorption method and the temperature-programmed desorption (TPD) of ethylamine. The ϵ-caprolactam selectivity of FSM-16 is improved by supporting Al2O3, ZnO and CdO. It was found that acid sites with the heat of adsorption of ethylamine around 135 kJ mol−1 are effective to increase ϵ-caprolactam selectivity. On the other hand, deactivation of the catalysts proceeds more rapidly with increase in the amount of strong basic sites. It is concluded that modification of FSM-16 by oxides is an effective method of improving the catalytic properties of FSM-16 for the vapor-phase Beckmann rearrangement of cyclohexanone oxime.