Study On Carbon Supported Copper-based Catalysts For Carbonate Synthesis By Oxidative Carbonylation

Dialkyl carbonates (e.g. dimethyl carbonate and diethyl carbonate), as a kindof “green chemicals”, have many applications, such as reaction intermediates (e.g.alkylating and carbonylating agents), fuel additives and solvents. Syntheticprocess that uses oxidative carbonylation to produce dialkyl carbonates is in linewith the principles of green chemistry and thus attracts more attentions. Thisdissertation focuses on the structure-activity relationship of the carbon materialsupported copper-based catalysts used in this catalytic reaction system. Theeffect of structure and surface chemical property of carbon carrier on thecatalytic performance was determined. The role of carbon carrier and activecentre in Cu2O/AC catalyst were revealed. The effect of active componentvalence state on the catalytic performance of CuOx/AC catalysts was proposed.Ordered mesoporous carbons (OMCs) were prepared and applied forWacker-type catalyst preparation. The structure property and dispersion of OMCssupported catalysts were characterized, and their catalytic activities wereevaluated. It was found out that the orderd mesopore structure of carbon carrierwas favorable for the dispersion of active component, further improving thecatalytic property. Moreover, the effect of surface property of carbon carrier onthe catalytic performance was determined through modifying the carbon carrier.It turned out that the surface oxygen containing groups (OCGs) played animportant role in anchoring the active species, and to gain a certain amount ofOCGs could increase the stability of the catalysts.Many methods for preparing chlorine-free carbon material supportedcatalysts were studied. Through characterization and catalytic activity evaluation,ethylene glycol reduction method was determined as a highly dispersion andstable Cu2O/AC catalyst preparation method. And the catalyst reduced at383Khad the best dispersion of Cu2O particles and showed the best catalyticperformance.The performance of the supported-Cu2O catalyst was strongly affected bythe type of support (MCM-41, graphene and AC). It was indicated that the carboncarrier, especially the surface OCGs, played a key role in the oxidative carbonylation. The optimal Cu loading as well as catalytic activity increasedlinearly with the amount of OCGs. The carbon carrier was found to have played asynergistic catalytic role in the reaction. The active center of the Cu2O/ACcatalyst was the Cu2O nanoparticles which coordinated to the OCGs on thecarbon surface.Three CuOx/AC catalysts with single valance state of copper (i.e. Cu0/AC,Cu2O/AC and CuO/AC) were synthesized and studied for catalytic oxidativecarbonylation. AC supported copper oxide catalysts (Cu2O/AC and CuO/AC)have shown the best catalytic performance. The interactions between copperoxides and the carbon carrier were stronger than the interaction between Cu0andthe support, which made the catalysts (Cu2O/AC and CuO/AC) a higher andmore stable catalytic property. The oxygen partial pressure in the reaction systemhas played an important effect on the catalyst catalytic performance. And thecatalytic activity of the catalysts could be improved effectively throughincreasing the oxygen partial pressure appropriately.