焙烧温度对CO2加氢合成二甲醚催化剂的影响

Effects of Calcination Temperature on the Performance of CuO-ZnO-Al_2O_3/HZSM-5 Catalyst for the Synthesis of Dimethyl Ether by Hydrogenation of Carbon Dioxide

考察了焙烧温度对二氧化碳加氢合成二甲醚催化剂CuO-ZnO-A l2O3/HZSM-5的影响,研究结果表明,焙烧温度为673 K时,催化剂中CuO和ZnO的相互分散程度较好,催化剂中氧化铜物种比较容易还原,复合催化剂表面具有较强的酸性中心,对于二氧化碳加氢直接合成二甲醚的催化活性最为理想。焙烧温度过高,会导致催化剂中CuO和ZnO粒子发生聚集、长大甚至烧结,催化剂的比表面积急剧下降,催化剂的还原变得困难,催化剂对氢的吸附量减小,催化剂的表面酸量减少,较强的表面酸中心消失,催化活性显著降低。

Effects of calcination temperature on the performance of CuO-ZnO-Al2O3/HZSM-5 catalyst for the synthesis of dimethyl ether by hydrogenation of carbon dioxide were investigated. It was found that the catalyst calcined under the temperature of 673 K showed better catalytic activity for dimethyl ether synthesis. The CuO and ZnO in the calcined catalyst sample were of better dispersion, so the CuO species in the catalyst was reduced more easily, and there were more and stronger acidic sites on the surface of the composite catalyst, which might contribute to the better catalytic activity. Too much higher calcination temperature could lead to conglomeration and sinter among CuO and ZnO particles, the specific surface area decreased remarkably, the reduction of CuO species in the catalyst became more difficult, the adsorption sites for hydrogen and the acidic sites on the surface of the composite catalyst were both reduced, and so the catalytic activity fell down obviously.