Preparation Of Au Based Catalysts And Catalytic Oxidation Of Sucrose To Gluconic Acid

The depletion of fossil resources has promoted the exploration and development of renewable raw materials to replace fossil resources.Biomass has great potential as fuel,chemical intermediates and raw materials.The oxidation of alcohols to carboxylic acids has been widely concerned.As a multifunctional platform chemical for biomass,gluconic acid is used to manufacture many useful products,such as nylon,plastics and food additives.In this paper,the preparation of Au based catalysts and their catalytic oxidation of sucrose to gluconic acid were studied.The effects of metal components and supports on the oxidation performance of the catalysts were investigated.A series of Au Cu/Ti O₂ catalysts were prepared and characterized by XPS,TEM and UV-Vis.The activity of the catalysts with different Au/Cu mass ratio,metal valence and metal particle size was compared,and the best catalyst was selected,The effects of reaction conditions on the oxidation of sucrose to gluconic acid were systematically studied.The results show that weak acid and medium strong acid are beneficial to the conversion of sucrose,and the best carrier for sucrose oxidation is Ti O₂.Au Cu/Ti O₂ catalyst has stronger synergistic effect,and the optimal Au/Cu mass ratio is 1/1.The rich Cu O on the surface of the catalyst is beneficial to the oxidation of sucrose.The bimetallic catalyst calcined at 400℃formed Au-Cu O composite structure and showed the best activity.Au₁Cu₁/Ti O₂-O catalyst has particle size sensitivity,and the optimal particle size is 6.4 nm.Compared with the catalyst reduced in H₂,the catalyst calcined in O₂ showed higher activity.Au₁Cu₁/Ti O₂-O bimetallic catalyst can selectively oxidize sucrose to gluconic acid under mild conditions.The optimal reaction temperature is 105℃,reaction pressure is 1 MPa and reaction time is 5 h.