铜锌原子比对CuO-ZnO/Al_2O_3催化剂合成甲醇性能的影响

以铝乳液的形式引入Al,采用反加共沉淀法制备了一系列Cu与Zn的原子比(简称Cu/Zn原子比)不同的CuO-ZnO/Al2O3催化剂;以合成气为原料,在固定床微型连续流动反应器中评价了CuO-ZnO/Al2O3催化剂合成甲醇的性能;采用XRD、H2-TPR和BET等方法对催化剂进行了表征,考察了Cu/Zn原子比对CuO-ZnO/Al2O3催化剂合成甲醇性能的影响。实验结果表明,Cu/Zn原子比的变化对催化剂前体的物相组成和催化剂的活性有明显影响;当Cu/Zn原子比为3时,催化剂的初活性和耐热后活性最高,其前体中含有较多的锌-孔雀石相((Cu,Zn)2CO3(OH)2),该物相分解时生成还原温度较低的CuO-ZnO固溶体,使Cu与Zn的相互作用增强,提高了催化剂的活性。

Influence of Cu/Zn Atomic Ratio on Properties of CuO-ZnO/Al2O3 Catalysts in Methanol Synthesis

A series of CuO-ZnO/Al2O3 catalysts with different Cu/Zn atomic ratios were prepared by the reverse co-precipitation method,in which Al was added in the form of aluminum emulsion.The catalytic property of CuO-ZnO/Al2O3 catalysts for methanol synthesis from syngas was evaluated in a continuous flow fixed-bed microreactor.The effects of Cu/Zn atomic ratios on properties of the CuO-ZnO/Al2O3 catalysts in the methanol synthesis were studied and the catalysts were characterized by means of XRD,H2-TPR and BET.The Cu/Zn atomic ratio significantly influenced both the phase structures of the catalyst precursors and the activities of the catalysts.When the Cu/Zn atomic ratio was 3,the catalyst activities before and after thermal test were the highest,and the corresponding precursors contained relatively much Zn-malachite phase[(Cu,Zn)2CO3(OH)2].CuO-ZnO sosoloid with low reduction temperature was obtained from Zn-malachite phase during decomposition,which could enhance the interaction between Cu and Zn,so the catalyst activity was improved.