HYDROCRACKING OF DIPHENYLMETHANE AND TETRALIN OVER BIFUNCTIONAL NIW SULFIDE CATALYSTS SUPPORTED ON 3 KINDS OF ZEOLITES

Hydrocracking reactions of diphenylmethane and tetralin were carried o ut over three kinds of zeolites with or without NiW sulfide to discuss the roles of catalytic bifunctionality in two types of hydrocracking reactions. It was found that strong acid sites were not needed for the hydrocracking of diphenylmethane, while the conversion of tetralin re quired relatively strong acid sites. Ultra-stable Y zeolite with stron g acidity exhibited high hydrocracking activity for both reactions. In contrast, mordenite catalysts did not show high activity for either h ydrocracking, though, isomerization of tetralin and excess hydrocracki ng to gaseous products proceeded. The superior performances of ultra-s table Y zeolite in the tetralin hydrocracking were suggested to be rel ated to the hydrogen transfer ability. In most cases, the loading of N iW sulfide enhanced catalytic activity. In the diphenylmethane hydrocr acking, the role of NiW sulfide was found to supply active hydrogen to the hydrocracking active sites on zeolite and to prevent polymerizati on of benzyl cations. In the tetralin hydrocracking, the dehydrogenate d products from tetralin were rehydrogenated over NiW sulfide. (C) 199 8 Elsevier Science B.V. All rights reserved.