VAPOR-PHASE BECKMANN REARRANGEMENT OF CYCLOHEXANONE OXIME OVER AN HY ZEOLITE CATALYST CALCINED AT HIGH-TEMPERATURE

The vapor-phase Beckmann rearrangement of cyclohexanone oxime over an HY zeolite calcined at high temperatures was investigated. Cyclohexanone oxime was rearranged into epsilon-caprolactam with high conversion at 573 K over an HY zeolite calcined at 873 K. The activity decay was slight, while oxime conversion over an HY zeolite calcined at 773 K steeply decreased during the initial stage of the reaction. The catalytic activity for the rearrangement was not correlated with the physical properties of a fresh catalyst, but with those of a used one, especially regarding their porosity and acidity. It was also found that the produced epsilon-caprolactam was tightly adsorbed on strong aicd sites, filling the micropores of the zeolite during the initial stages of the reaction, and that a large portion of the catalytic reaction proceeded mainly on weak acid sites located in a region near to the external surface of the zeolite.