ACID-CATALYZED HYDROGENATION DURING KEROSENE HYDRODEWAXING OVER H ZSM-5/

Hydrogen addition to the products derived from cracking kerosene over- H/ZSM-5 was observed at hydrogen pressures between 4.1-8.7 MPa and at 373-390 degrees C. At low pressures, kerosene cracking over H/ZSM-5 yi elded typical cracked products: aromatics, as well as low molecular we ight saturates and olefins. Endothermic reactor temperature profiles w ere also observed, indicative of cracking reactions. At high hydrogen partial pressures product selectivity was altered in that kerosene cra cking gave high yields of low molecular weight paraffins and low yield s of olefins and aromatics. Reactor temperature profiles were exotherm ic, indicative of hydrocracking reactions. A mechanism for acid cataly zed hydrogenation is suggested. Although hydrogenation was not observe d at lower hydrogen pressures, hydrogen proved beneficial in maintaini ng catalyst activity at a stable level. Lost catalyst activity was res tored by maintaining the catalyst under static hydrogen at 1.4 MPa and 370 degrees C for 16 h. (C) 1996 Academic Press, Inc.