Copper carbide composite catalyst for hydrogenolysis of glycerol to 1,2-propanediol

The hydrogenolysis of renewable glycerol towards 1,2-propanediol (abbreviate as 1,2-PDO) has been a promising approach. In this work, high-performance catalysts containing copper carbide (CuxC) were prepared by the following procedure: (1) synthesis of Cu(OH)2-Zn(OH)2 mixture via a microchannel reaction system, (2) thermal treatment at 100 °C in 0.50 vol% C2H2/Ar gas, and (3) reduction at 300 °C under H2 atmosphere. The continuous synthesis of Cu(OH)2-Zn(OH)2 mixture in a microchannel reaction system yielded highly dispersed precursors, and the addition of ZnO led to improved dispersion of copper species with enhanced acidity. The new crystal phase, copper carbide (CuxC), was generated through reacting Cu(OH)2 particles with C2H2/Ar and subsequent hydrogen reduction. CuxC exhibited significantly higher hydrogenation activity than Cu metal, and contributed to enhanced catalytic activity for continuous glycerol hydrogenolysis in the fixed-bed reactor. Copper carbide composite catalyst (Cu/Zn = 8) afforded 100 % glycerol conversion and high selectivity (92.3 %) towards 1,2-PDO at 240 °C, 2.0 MPa and WHSV 3 h−1.