Unexpected Catalytic Performance of Cu-Ni Bimetallic Catalysts in Hydrogen-Free In-Situ Glycerol Hydrogenolysis: A Failed Attempt Toward 1,2-Propenediol Production

Abstract

This work reports an unsuccessful attempt to develop Cu–Ni bimetallic catalysts for hydrogen-free in-situ glycerol hydrogenolysis to 1,2-propanediol (1,2-PDO). Based on the known strengths of monometallic Cu (high 1,2-PDO selectivity under external H2) and monometallic Ni (in-situ hydrogen production via glycerol reforming), a series of Cu–Ni/Al2O3 catalysts with varying Cu/Ni mass ratios and Ni-based catalysts modified with different promoters (Y, La, Ce, Cu) were evaluated under identical hydrogen-free conditions.were prepared and evaluated under identical hydrogen-free conditions. Contrary to the expected synergistic effect, the bimetallic catalysts delivered inferior performance compared to monometallic Ni/Al2O3: glycerol conversion decreased significantly with increasing Cu content, and 1,2-PDO selectivity was suppressed in all bimetallic formulations. Instead, the reaction shifted toward undesired C–C cleavage and formation of acetol and light oxygenates.