Efficient Catalytic Hydrogenation of Glucose to Sorbitol over Metallic Nickel-Rich Nickel Borides under Mild Reaction Conditions

Catalytic hydrogenation of carbohydrates over the Raney Ni catalyst is an important industrial process to produce valuable polyols. However, this process generally encounters challenges such as harsh reaction conditions, low catalytic activity, and catalyst deactivation. In this contribution, metallic nickel-rich nickel borides (NiBO-nKH2PO4) were successfully constructed via a simple chemical reduction method with potassium dihydrogen phosphate (KH2PO4) as the buffering agent and sodium borohydride (NaBH4) as the reducing reagent. Especially, the obtained NiBO-10KH2PO4 afforded quantitative sorbitol yield from the catalytic hydrogenation of glucose under mild reaction conditions within 1 h (80 °C and 1 MPa H2). Compared with the reported literature for the production of sorbitol from glucose, the developed NiBO-10KH2PO4 catalyst circumvents the use of a high hydrogen pressure and reaction temperature while delivering excellent catalytic performance and stability. Moreover, the experimental analysis demonstrated that the obtained nickel borides, with the assistance of KH2PO4, possessed abundant metallic nickel species, which favored the adsorption and activation of hydrogen molecules and thus largely promoted the hydrogenation of glucose. This work provides new insights into the rational design of practical nickel-based catalysts for the efficient catalytic hydrogenation of carbohydrates.