Selective Cellulose Hydrogenolysis to Ethanol Using Ni@C Combined with Phosphoric Acid Catalysts

Ethanol is an important bulk chemical with diverse applications. Biomass-derived ethanol is traditionally produced by fermentation. Direct cellulose conversion to ethanol by chemocatalysis is particularly promising but remains a great challenge. Herein, a one-pot hydrogenolysis of cellulose into ethanol was developed by using graphene-layers-encapsulated nickel (Ni@C) catalysts with the aid of H3PO4 in water. The cellulose was hydrolyzed into glucose, which was activated by forming cyclic di-ester bonds between the OH groups of H3PO4 and glucose, promoting ethanol formation under the synergistic hydrogenation of Ni@C. A 69.1 % yield of ethanol (carbon mole basis) was obtained, which is comparable to the theoretical value achieved by glucose fermentation. An ethanol concentration of up to 8.9 wt % was obtained at an increased cellulose concentration. This work demonstrates a chemocatalytic approach for the high-yield production of ethanol from renewable cellulosic biomass at high concentration.