Hydrogenolysis of Glycerol to Propanediols over Ni supported on MgO Catalyst

A Ni/MgO catalyst was used to undergo hydrogenolysis of glycerol, a byproduct of biodiesel synthesis, in the aqueous phase at different nickel loadings (10–40% by weight). The wet impregnation-prepared catalysts were characterized by XRD, SEM, TPR, and BET methods and showed strong metal-support interaction, good Ni dispersion, and high surface area, respectively. The catalytic activity in a batch reactor was measured at 220°C, 3 MPa hydrogen pressure, and 20 hours of reaction time. Glycerol conversion exhibited an increasing trend with Ni loading in the following sequence: 10%Ni/MgO < 20%Ni/MgO < 30%Ni/MgO < 40%Ni/MgO. The 20%Ni/MgO catalyst yielded the highest 1,2-propanediol (1,2-PDO) production, with a subsequent decrease observed at higher Ni loadings. In particular, the 20%Ni/MgO catalyst produced a 74% total glycerol conversion and a 76% selectivity toward 1,2-PDO. The optimal reaction conditions were then ascertained by examining the effects of temperature (200–240°C), glycerol content (5%–30% by weight), hydrogen pressure (3–5 MPa), and reaction time (6–25 hours) on the activity of the 20%Ni/MgO catalyst.