铜锌比对CuO-ZnO-ZrO_2催化剂CO_2加氢合成甲醇性能的影响

Effect of Cu/Zn ratio on properties of CuO-ZnO-ZrO_2 for methanol synthesis from CO_2 hydrogenation

采用并流共沉淀法制备了一系列不同铜锌原子比的CuO-ZnO-ZrO2催化剂,通过X射线衍射、N2物理吸附、H2程序升温还原和CO2吸附-脱附等对催化剂结构进行了表征,并在固定床微催化反应器上评价了催化剂的CO2加H2合成甲醇活性。研究表明,适宜的Cu/Zn有利于提高活性组分分散度,同时形成Cu-Zn协同活性位,提高表面强碱性位强度及数量,从而提高催化剂转化率以及甲醇选择性。当n(Cu)/n(Zn)=1时,催化剂的CO2转化率、甲醇选择性达到较好值,分别为22.0%和28.8%。

A series of CuO-ZnO-ZrO2 catalysts with various Cu/Zn atomic ratios were prepared by co-precipitation. The catalysts were characterized by XRD, N2 adsorption-desorption, H2-TPR and CO2-TPD, and their catalytic properties in hydrogenation of CO2 to methanol were investigated in a fixed-bed microreactor. The results showed that the reducibility and dispersion of the catalysts and the basic sites on the catalyst surface strongly depended on their Cu/Zn atomic ratios. Appropriate Cu/Zn atomic ratio could greatly improve the dispersion of CuO, promote the formation of Cu-Zn synergistic active sites and enhance the intensity and number of the surface strong basic sites of catalysts, which resulted in the increase of CO2 conversion and methanol selectivity. The catalyst with a Cu/Zn atomic ratio of 1/1 showed better CO2 conversion and methanol selectivity, which were 22.0%and 28.8%, respectively.