Catalyst deactivation of high silica metallosilicates in Beckmann rearrangement of cyclohexanone oxime

The vapor phase Beckmann rearrangement was carried out over high silica ZSM-5 type metallosilicates to elucidate the effect of acid strength on epsilon-caprolactam selectivity and catalyst deactivation rate. It was found that the indiosilicate which had the lowest acid strength was the best catalyst among the metallosilicates. When carbon dioxide and methanol were used as diluent gas and diluent solvent of cyclohexanone oxime, respectively,the deactivation rate decreased over indiosilicate. Furthermore, when the indiosilicate was modified with a precious metal, the catalyst deactivation significantly decreased. It was considered that the oxidation of coke on the surface was accelerated by the precious metal.