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

Abstract

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.