焙烧温度对MgO修饰Cu/ZnO催化剂结构及催化草酸二甲酯加氢反应研究

采用共沉淀法制备了系列掺杂Mg2+离子的Cu-Mg/ZnOn(Cu)∶n(Zn)=5∶4]催化剂,并用N2吸附-脱附、XRD和H2-TPR等对催化剂进行表征,考察焙烧温度对催化剂结构及其催化草酸二甲酯加氢反应性能的影响。结果表明,经350℃焙烧所得Cu-Mg/ZnO-c350催化剂具有较大的比表面积,发达的介孔结构,较高的Cu物种分散性和较多的表面Cu0活性位;而较高的焙烧温度导致催化剂中纳米粒子聚集烧结,降低催化剂比表面积、孔径尺度和表面Cu0活性物种数量。适宜反应条件,Cu-Mg/ZnO-c350催化剂催化草酸二甲酯气相加氢反应转化率为100%,乙二醇收率为95%。此外,较强的金属-载体作用力抑制铜活性物种的抗烧结能力,赋予其优异的稳定性。

Effect of calcination temperatures on the structure and performance of MgO modified Cu/ZnO catalysts for dimethyl oxalate hydrogenation

A series of Mg²⁺ modified Cu/ZnO n(Cu):n(Zn)=5:4] nanocomposites catalyst were prepared by co-precipitation method and characterized by XRD,N₂ adsorption-desorption and H₂-TPR.The influence of calcination temperatures on the structure and performance of the catalysts for dimethyl oxalate(DMO) hydrogenation was investigated.The results showed that Cu-Mg/ZnO-c350 catalyst calcined at 350 ℃ possessed larger BET surface area,well developed meso-pore structure,higher Cu dispersion and more active surface Cu⁰ sites exposed.Higher calcination temperature led to sintering nano-particles in catalyst,decrease of surface area,pore diameter and amount of active surface Cu⁰ sites exposed.In DMO hydrogenation process over Cu-Mg/ZnO-c350 catalyst,DMO conversion of 100% and the selectivity to ethylene glycol of 95% were attained under the optimum reaction condition.Additionally,the strengthened metal-support interaction force inhibited anti-sintering ability of copper active species and benefited the superior stability.