Catalytic hydrodeoxygenation of biomass-derived oxygenates to bio-fuels over Co-based bimetallic catalysts

Abstract

The rapid consumption of conventional fossil fuels has caused a sharp decline in their reserves and led to climate change. Exploitation of renewable energy sources especially bio-fuels such as 2,5-dimethylfuran (DMF), methylfuran (MF), γ-valerolactone (GVL), etc. has both environmental and economic benefits. In the present work, diverse Co-based bimetallic catalysts were prepared and used for catalyzing hydrodeoxygenation (HDO) of biomass-derived oxygenates. Co₅Zn₁O_x, obtained by the incorporation of Zn species into the Co metal catalyst especially with a Co/Zn molar ratio of 5, could enhance the catalytic performances obviously compared to the sole Co catalyst. For example, the DMF, MF, and GVL yields reached up to 94, 98, and 77% during the catalysis by Co₅Zn₁O_x, which were much greater than 74, 0, and 23% for the Co catalyst, respectively. The enhanced performances of Co₅Zn₁O_x stem from the strong interaction between the Co and Zn species. Specifically, the presence of ZnO could stabilize Co²⁺ species, by offering electrons to Co species and creating oxygen vacancies, resulting in Co₅Zn₁O_x showing the highest adsorption amounts of furfural and furfuryl alcohol compared to Co₁Zn₁O_x and Co₇Zn₁O_x catalysts. Moreover, the catalyst showed good universality and reusability, and the HDO of 5-HMF to DMF proceeded in a true heterogeneous manner. The present work is believed to extend the application of bimetallic catalysts to the synthesis of bio-fuels and utilization of biomass materials.