Solvent assisted to prepare shell structured Cu/γ-Al2O3 catalyst with low Cu content for oil efficient hydrodeoxygenation to high-quality biofuel

Abstract

Using biomass “green carbon” can effectively alleviate the energy crisis and environmental protection problems. To achieve efficient removal of oxygen atoms, retain complete carbon chain structures, and maximize the economy of carbon atoms for the inedible or waste bio-oils, a novel and unique shell-style Cu/γ-Al2O3 catalyst with low Cu content was developed to solve the current problems including easy sintering and poor hydrodeoxygenation (HDO) activity of the studied catalysts. The shell Cu/γ-Al2O3 catalyst (Cu-CPA) with the Cu content of 3 wt% prepared by acetone as solvent has excellent cycle-stable HDO performances, the methyl laurate hydrogen conversion and C12 alkanes selectivity were 87.2 and 80.0 % at 400 °C, respectively, which were equivalent to the activities of the ordinary 10 wt% Cu/γ-Al2O3 catalyst prepared by wet impregnation using water as a solvent. The polarity of the impregnating solution modulates the shell layer thickness of the Cu-based catalysts to improve the surface chemical composition and pore structure of the catalysts, which in turn affects the lipids HDO performances of the corresponding catalyst. Active heterogeneous shell Cu-CPA catalyst showed high activity, selectivity, and stability in HDO, which can be attributed to the unique structure with suitable active shell thickness and high utilization rate of the metal Cu active components. This study provides feasible ideas for the preparation of shell-type catalysts, the design of anti-sintering Cu-based catalysts, and the production of renewable biofuels.