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以尿素为燃烧剂,先采用燃烧法制备CuO-ZnO催化剂,接着采用研磨法将其与HZSM-5分子筛均匀混合形成CuO-ZnO/HZSM-5双功能催化剂.采用固定床反应器,在反应温度260℃、压力3.0 MPa、空速1 500 h-1条件下,考察了不同Cu/Zn(摩尔比)催化剂在CO_2加氢合成二甲醚反应中的催化性能.通过XRD、N_2等温吸附脱附、H2-TPR、NH3-TPD对催化剂进行表征,研究了不同Cu/Zn对催化剂结构及表面酸性的影响.结果表明:当Cu∶Z n=6∶4时,催化剂对CO_2催化加氢直接合成二甲醚反应的催化活性和选择性最佳,CO_2的转化率、DME的选择性分别为11.95%和28.74%,且在催化剂上具有更多的低温还原Cu和较强的酸中心,从而提高了CO_2加氢活性和二甲醚的选择性.
Using urea as the combustion agent, the CuO-ZnO catalyst was firstly prepared by the combustion method and then uniformly mixed with the HZSM-5 molecular sieve to form a CuO-ZnO / HZSM-5 bifunctional catalyst by using a grinding method. The catalytic performance of different Cu / Zn catalysts in the dimethyl ether reaction of hydrogenation of CO_2 was investigated at 260 ℃, pressure of 3.0 MPa and space velocity of 1 500 h-1. The isothermal adsorption and desorption , H2-TPR and NH3-TPD were used to characterize the catalysts. The effects of Cu / Zn on the structure and surface acidity of the catalysts were investigated. The results showed that when Cu:Z n = 6: 4, the catalysts were directly synthesized by catalytic hydrogenation of CO 2 Dimethyl ether reaction has the best catalytic activity and selectivity. The conversion of CO 2 and the selectivity of DME are 11.95% and 28.74%, respectively, and more Cu and stronger acid sites are reduced on the catalyst to increase the CO_2 hydrogenation activity and dimethyl ether selectivity.