Bifunctional catalyst with high efficiency for converting hydrocarbons: The enhanced diffusion between micro and meso-pores

The influences of the distance between the hydrogenation center and cracking center and diffusivities of catalysts on hydrocracking behaviors were investigated. It was initially found that, compared with the catalysts with only micromeso-Y zeolite or meso-Al2O3, the diffusivities of combined catalysts with both Y zeolite and Al2O3 could be significantly improved. The NiW/Y-A catalyst presents the best diffusivity due to the introduction of pure meso-Al2O3. The property of active metals and acidity play an important role on the adsorption ability of catalyst. The n-dodecane hydrocracking results showed that the NiW/Y-A catalyst with the lowest dispersion degree of metals, acidity and proportion of active WS2 phase presented the highest activity due to its superior diffusivity. The results also revealed that a closer distance between the hydrogenation and cracking centers leads to a higher selectivity of iso-cracking, liquid yield and better stability of catalysts. The above findings provide a potential novel method for designing catalysts with high activities and selectivities.