Aqueous phase hydrogenolysis of glycerol with in-situ hydrogen generation over Ni catalysts supported on activated carbon: Effects of nickel loading and base addition

The present work studied the influences of nickel loading and KOH addition on the aqueous phase hydrogenolysis of glycerol over nickel supported on activated carbon (Ni/AC) catalysts prepared by the incipient wetness impregnation method and without external hydrogen addition in a continuous operation. It has been observed that the calcination stage of the catalytic precursor reduces nickel oxide to dispersed nickel metal crystallites, making catalyst activation with hydrogen unnecessary. This process predominantly yields liquid products, with low gas production under the studied conditions. Among the produced liquids, acetol and 1,2-propanediol are the major components. Furthermore, the addition of a base (KOH) is beneficial both in terms of significantly increasing glycerol conversion and the yield to liquids and also to improve selectivity towards 1,2propanediol due to the participation of the basic route. The best catalytic activity was achieved using the catalyst with 10 wt% of Ni and added base with the highest glycerol conversion close to 40 % and selectivity to 1,2-propanediol greater than 70 %.