Catalytic ability of plasma heat-treated metal oxides on vapor-phase Beckmann rearrangement

The vapor-phase Beckmann rearrangement of cyclohexanone oxime for epsilon-c aprolactam catalyzed by various metal oxide powders was studied by using a flow reactor system. It was shown that there is a correlation between the e psilon-caprolactam selectivity and electronegativity of the catalysts. The most effective catalyst for this reaction was niobium oxide, which was prep ared by the microwave cold plasma heating method. This means that the surfa ce characteristics of metal oxides prepared by the plasma heating are diffe rent from those prepared by the electric furnace heating method. (C) 1999 E lsevier Science S.A. All rights reserved.