Origin of Hydrocracking Functionality in β-Zeolite-Supported Tungsten Catalysts

H-β-zeolite-supported tungsten sulfide catalysts with W loading varying between 10 and 25 wt % were prepared and characterized by BET surface area, pore size distribution in micro- and mesopore regions, in situ microcalorimetric ammonia adsorption, and oxygen chemisorption at low temperatures on sulfided catalysts. The thiophene HDS, cyclohexene hydrogenation (HYD), and cumene hydrocracking (HCK) reactions were carried out on sulfided catalysts. The differential heat curves and acid strength distributions indicated that sulfiding and WS2 content have a profound influence on the acidic properties of these catalysts. It was concluded that zeolite and WS2 both contribute to the acidic properties of the catalysts. There exists a correlation between strong acid sites and HCK activity. The relation between initial heat of adsorption and HCK activity suggested that acid sites ≥100 kJ/mol are involved in cumene hydrocracking on these catalysts.