Cellulose hydrogenolysis to alcohol and ketone products using Co@C catalysts in the phosphoric acid aqueous solution

Cellulose hydrolysis and further conversion to diketones and alcohols was performed with graphene layer encapsulated cobalt catalysts (Co@C) in phosphoric acid aqueous solution. A total of 60.5% yield of the products mainly including ethanol, 2,5-hexanedione (2,5-HD) and diols could be achieved in 0.06 M H3PO4 solution. A series of characterization methods such as XRD, XPS, TEM, TG-MS, BET, ICP, H2-TPD, NH3-TPD, and Raman were carried out to explore the catalyst formation mechanism and reaction activity. The results of the analysis indicated that the calcination temperature had a deep influence on the structure formation of the Co@C catalysts, thus leading to differences in the reaction activity. While the calcination temperature was determined at 700 °C, the Co@C catalyst meets with the requirements of optimal reaction activity, appropriate particle size, suitable surface area, and pore size. Besides, it was found that H3PO4 is not only favorable in cellulose hydrolysis but also cooperates with the Co@C catalyst in the hydrogenolysis of C–O bond and C–C bonds for the formation of products. This work provides a possible way for renewable cellulose conversion to diketone and alcohols over encapsulated non-noble metal catalyst combined with phosphoric acid aqueous solution.