Влияние кислотны х характеристик цеолитов на активность и селективность NiMo-катализаторов гидрокрекинга к дизельной фракции

Abstract

In the present study, we investigated the influence of acid properties of NiMo hydrocracking catalysts on activity and selectivity to the diesel fraction. NiMo catalysts were prepared with using following acid components: ultrastable zeolite Y (UZ-Y), recrystallized zeolite Y (RMZ-Y) and nanocrystalline zeolite BEA (NCZ-BEA). Hydrocracking catalysts were tested in a down-flow, fixed bed reactor. Concentration and strength of Bronsted (BAS) and Lewis (LAS) acid sites of the zeolites were determined by infrared spectroscopy of adsorbed CO. Supports containing γ-Al2O3 and 20, 30 or 40 wt. % of UC-Y zeolite were prepared. It was shown that the higher zeolite content the higher activity and the lower selectivity to diesel fraction of the catalysts are. Testing of the catalysts prepared from different zeolites in hydrocracking showed that selectivity to diesel fraction is greatly influenced by the ratio of BAS concentration on outer surface of zeolite crystals to concentration strongest BAS on internal surface.