制备条件对Cu-MnO_x低温液相甲醇合成性能影响

Effect of Preparation Conditions on Catalystic Performance of Cu-MnO_x for Low-temperature Methanol Synthesis

采用并流共沉淀法制备Cu-MnOx催化剂,用于合成气CO/CO2/H2为原料的低温液相甲醇合成.研究了制备条件对Cu-MnOx结构及催化性能的影响,XRD、H2-TPR、CO-TPD表征显示,制备过程中的沉淀p H、煅烧温度等影响Cu-Mn Ox中CuO的分散性、还原性能和对CO的吸附能力.沉淀p H为7、煅烧温度450℃制备的铜锰摩尔比为1∶1的Cu-Mn Ox铜锰相互作用强,CuO分散好,形成的Cu1.5Mn1.5O4晶相利于中间产物甲酸酯的生成,并且其对CO的吸附能力强,H2还原温度适中,利于在预还原条件下生成较多Cu+,因此,表现出最好的催化性能.在170℃、5 MPa反应条件下,以K2CO3为助剂、乙醇为溶剂,碳转率为71.8%,甲醇选择性55.9%,同时生成了较多的碳链增长产物,说明CO在该催化剂上可发生解离吸附,为乙醇等C2+低碳醇的合成提供参考.

Cu-Mn Oxcatalyst was prepared by co-precipitation method and was used for low-temperature methanol synthesis from syngas( CO / CO2/ H2). The effect of preparing conditions of Cu-Mn Oxcatalyst on the structure and catalytic performance were studied by XRD,H2-TPR and CO-TPD. The results showed that the Cu / Mn molar r atio,the precipitation p H and the calcination temperature affected the CuO dispersion,the reducibility and the adsorption capacity of CO of Cu-Mn Ox. Using ethanol as solvent and K2CO3 as additive at 170 ℃ and 5MPa,the highest carbon conversion of 71. 8% along with a methanol selectivity of 55. 9% was obtained over the Cu-Mn Ox with Cu / Mn molar ratio of 1 prepared at the p H value of 7 and the calcination temperature of 450 ℃. For the CuMn Oxprepared under the optimum preparation conditions,a strong intereaction between Cu and Mn,highly dispersed Cu O,a strong adsorption capacity of CO and a suitable reduction temperature were obtained. Therefore,more Cu+would be attained on the catalyst reduced by H2,and Cu+was favourable for the low-temperature methanol synthesis. In addition,ethyl acetate was obtained over Cu-Mn Ox,which indicated that CO was dissociated on the catalyst and would provide a reference for higher alcohols synthesis.