Supported Copper Catalysts for D-Glucose Hydrogenation to D-Sorbitol under Mild Conditions

Abstract

In this study, bulk copper catalysts and copper catalysts supported on α- and γ-Al₂O₃ were synthesized. A copper–ammonia–carbonate solution (CACS) was used as a copper precursor. The structure and textural properties of the synthesized catalytic systems were investigated, including their specific surface area, pore volume, and coherent scattering region size. The optimal catalyst reduction temperature in a hydrogen flow, which ensures maximum activity in the D-glucose hydrogenation process, was experimentally determined. It was established that γ-Al₂O₃ inhibits the thermal decomposition of basic copper carbonate. The catalyst activity in in liquid-phase reduction of D-glucose was estimated by the average reaction rate, as the reaction orders were close to zero. The optimal supported copper content was estimated to be 5.5–5.8 wt %, at which a maximum sorbitol synthesis rate is achieved. The resulting catalytic systems are not inferior in activity to similar catalysts, including those based on other transition metals, enabling the process under mild conditions (303 K, atmospheric hydrogen pressure). The attained catalytic activity was 11.9 ± 1.3 \({\text{cm}}_{{{{{\text{H}}}_{{\text{2}}}}}}^{{\text{3}}}\) s^–1 \({\text{kg}}_{{{\text{Cu}}}}^{{ - 1}}\), while the conversion reached 5% in 2 h; for conventional nickel based catalysts, these parameters are close to zero under mild conditions and typically achieved only at high temperatures and increased pressures (up to 5 MPa).