Hydrogenolysis of glycerol to 1,2-propanediol without external H2 addition in alkaline medium using Ni-Cu catalysts supported on Y zeolite

Ni, Cu and Ni-Cu catalysts supported on NaY-zeolite (NaY) were prepared with 20 wt% of each metal by using wet impregnation method. They were characterized by X-ray fluorescence, X-ray diffraction, N2 adsorption-desorption, temperature-programmed reduction, temperature-programmed desorption of ammonia and temperature-programmed oxidation. The catalytic tests of glycerol hydrogenolysis were performed in alkaline medium (NaOH/glycerol molar ratios of 0, 0.25 and 0.5) employing continuous flow reaction system using a space velocity of 2 h−1 at 260 °C, and pressure of 46 bar for 30 h. The catalytic tests showed that the concomitant use of Ni and Cu proved to be more effective for the process of glycerol hydrogenolysis to 1,2-propanediol without the external H2 addition, since each metal plays a distinct role. The catalytic tests showed a significant increase in the yield to 1,2-propanediol with the addition of NaOH to the reaction medium; the highest conversion of glycerol (96.4%) and yield to 1,2-propanediol (31.8%) were obtained employing NaOH/glycerol molar ratio = 0.5 and Ni-Cu catalyst. No catalytic deactivation was observed for 30 h, showing that the catalysts exhibit good catalytic stability and good resistance to coke deposition.