沉淀剂对悬浮共沉淀法制备二甲醚催化剂的影响

以无水乙醇为溶剂,将Cu、Zn和Al的硝酸盐并流共沉淀在HZSM-5分子筛的悬浮溶液中,一步合成CuO-ZnO-Al2O3/HZSM-5双功能催化剂.研究了沉淀剂的种类、加入顺序和加入量对催化剂活性的影响.结果表明,以适量的草酸作沉淀剂,采用悬浮液并流共沉淀法制备的双功能催化剂,对CO2加氢直接合成二甲醚有较高的催化性能:在固定床反应器中,温度为270℃,压力为3.0 MPa,空速为4 800 h-1的反应条件下,CO2的单程转化率达到28.7%,二甲醚的选择性达到53.2%.BET、XRD、TPR、TPD和N2O滴定等对催化剂结构表征结果表明,双功能复合催化剂CuO-ZnO-Al2O3/HZSM-5的结构影响CO2加氢合成二甲醚的催化性能.

Influence of Precipitators on Catalysts for Synthesis of Dimethyl Ether Prepared by Suspended Coprecipitation Method

Bifunctional catalysts of CuO-ZnO-Al2O3/HZSM-5 for dimethyl ether synthesis from hydrogenation of CO2 were directly prepared by parallel-flow-coprecipitation method, using anhydrous ethanol as solvent. The influence of the kinds of precipitators, additive sequence and the amount of precipitators on the activity of the catalysts were investigated. The experiments results demonstrated that the as-prepared bifunctional catalysts showed higher catalytic activity for dimethyl ether synthesis. At 270℃, 3.0 MPa, space velocity 4800 h-1, the one way conversion of CO2 was 28.71%, the yield of dimethyl ether could reach 53.20 %. BET, XRD, TPR, TPD and N2O decomposition were employed to investigate the structure and surface performance of the catalysts. The results indicated the catalytic performance was determined by the structure of the catalysts.an interaction existed between the metal oxides, which exhibits with the composite effect of HZSM-5。