Oriented hydrocracking of naphthalene into high-value light aromatics over difunctional catalysts: the effect of hydrogen spillover and utilization of hydro-reaction characteristics for different active metals

Abstract

Serial difunctional catalysts supported on γ-Al2O3 and HY zeolite were synthesized and characterized systemically. The characterization results disclosed that hydrogen spillover existed in the NiMo and CoMo catalysts, and decreasing Ni/Mo and Co/Mo ratios could reduce hydrogen spillover. Meanwhile, the naphthalene hydrocracking behaviors over different catalysts were investigated and compared. The higher yield of cyclane for CoMo/AY catalysts demonstrated that hydrogen spillover could deeply hydrogenate naphthalene into cyclane. The combined catalysts of Ni/Y@CoMo/A, Ni/Y@NiMo/A and Ni/Y@Mo/A showed relatively lower conversions of naphthalene but higher yields of valued <C10 aromatics. The combined catalyst Ni/Y@CoMo/A presented the highest yield of light aromatics due to the appropriate reduction of hydrogen spillover and rational utilization of hydro-reaction characteristics for different active metals. Moreover, the stability of CoMo catalyst was higher than NiMo catalyst. The catalysts containing Co and Mo active metals presented low content of carbon deposition.