K2O助剂对合成碳酸二甲酯用Cu/Ni/ZrO2-SiO2催化剂的吸附和催化性能的影响

 用等体积浸渍法制备了ZrO2－SiO2（ZrSiO）表面复合氧化物负载的Cu－Ni催化剂，并用IR，TPR，TPD及微反技术考察了K2O助剂对CO2和CH3OH在Cu－Ni／ZrSiO催化剂表面上的吸附及合成碳酸二甲酯（DMC）反应性能的影响．结果表明：加入K2O助剂使CO2在催化剂表面上的吸附增强，当n（K）／n（Cu＋Ni）＝15％时，CO2在催化剂表面上吸附后生成K2CO3；CH3OH在催化剂表面上的解离吸附态（CH3O－和H＋）的吸附减弱；CO2和CH3OH在Cu－Ni／ZrSiO催化剂表面上反应的主要产物为DMC，H2O，CO和CH2O；随着K2O助剂的加入，反应转化率及DMC选择性提高，副产物（CO和CH2O）的选择性下降．根据实验结果，探讨了K2O对催化剂表面活性中心电荷分布的影响．

Effect of K2O on Adsorption and Reaction of CO2 and CH3OH over Cu-Ni/ZrO2-SiO2 Catalyst for Synthesis of Dimethyl Carbonate

ZrO 2-SiO 2(ZrSiO) supported Cu-Ni-K 2O catalyst for synthesis of dimethyl carbonate (DMC) was prepared by using isovolumetric impregnation. Based on IR, TPR, TPD and micro-reactor techniques, the effect of K 2O on adsorption and reaction of CO 2 and CH 3OH over the catalyst was studied. The results showed that the addition of K 2O has obvious influence on the charge distribution of active sites on Cu-Ni/ZrSiO catalyst, and increases the intensity of CO 2 horizontal adsorption state, while descends the intensity of dissociation state of methanol. When the K 2O content n(K)/n(Cu+Ni) is above 15%, K 2CO 3 is formed on the catalyst. Moreover, the main reaction products of CO 2 and CH 3OH on Cu-Ni-K 2O/ZrSiO catalyst are still DMC, H 2O, CO and CH 2O, and with the addition of K 2O, the conversion of reactants and the selectivity for DMC increase, but the selectivity for by-products decreases.