VAPOR-PHASE REACTION OF CYCLOHEXANONE OXIME OVER BORIA MODIFIED HSZM-5 ZEOLITES

The vapor phase Beckmann rearrangement of cyclohexanone oxime has been carried out over zeolites and boria modified HZSM-5 zeolites to elucidate the effects of acidity and acid strength distribution on the conversion and epsilon-caprolactam selectivity. Although epsilon-caprolactam selectivity was increased with the SiO2/Al2O3 ratio in a HZSM-5 zeolite, the highest selectivity in the study was accomplished over a boria modified HZSM-5. The selectivity was dependent on the ratio of weak acid sites to strong acid sites. The boria played an important role in controlling the acid strength distribution of the zeolites. It was found that the production of a polymer over strong acid sites caused a decrease in epsilon-caprolactam selectivity during the reaction.