Selective Hydrogenation of Diethyl Malonate to 1,3-Propanediol Over Ga-Promoted Cu/SiO₂ Catalysts With Enhanced...

Cu catalysts with different compositions and different Cu and promoter contents were prepared by precipitation-gel method and studied for the selective hydrogenation of syngas or biomass-based diethyl malonate (DEM) to valuable 1,3-propanediol (1,3-PDO). The Ga-promoted 70Cu6Ga/SiO₂ catalyst was found to exhibit the highest catalytic performance, achieving 100 % DEM conversion and 76.6 % 1,3-PDO selectivity under reaction conditions of 160 °C and 8 MPa H₂. The 70Cu6Ga/SiO₂ bimetallic catalyst also presented obviously better stability than that of the monometallic 70Cu/SiO₂ catalyst in a continuous flow reactor over 180 h time-on stream. Characterization results showed that the incorporation of Ga increased the interaction between Cu and Ga species, hindered the full reduction of Cu²⁺ species, and thus increased the proportion of Cu⁺ and the number of Lewis acidic sites on the catalyst surface. The synergistic effect between Cu⁰ and Cu⁺ enhanced the adsorption and activation of ester carbonyl groups and their subsequent hydrogenation, eventually contributed to the outstanding performances of the CuGa/SiO₂ bimetallic catalysts.