CuMgAlO_x复合氧化物催化甲醇乙醇Guerbet反应:M^(2+)/Al^(3+)比的影响

Guerbet reaction of methanol and ethanol catalyzed by CuMgAlO_x mixed oxides: Effect of M^(2+)/Al^(3+) ratio

以类水滑石为前驱体,通过调控M^(2+)/Al^(3+)比制备了系列具有不同表面性质的MgAlO_x(MA)和CuMgAlO_x(CMA)催化剂,并分别应用于甲醛乙醛缩合反应(甲醇乙醇Guerbet反应的第二步反应)和甲醇乙醇Guerbet反应。采用NH_3/CO_2-TPD、XPS、H_2-TPR和H_2-TPD技术对催化剂表面酸碱性以及铜物种的性质进行了表征。结果表明,甲醇乙醇Guerbet反应性能与催化剂表面Cu^0比表面积和中强碱数目有关,提高Cu^0比表面积有利于甲醇乙醇脱氢生成甲醛和乙醛,增强中强碱数目能促进甲醛乙醛缩合反应。

A series of hydrotalcite-like derived MgAlO x(MA)and CuMgAlO x(CMA)catalysts with various M 2+/Al 3+molar ratios were prepared and evaluated by the aldol condensation reaction of formaldehyde and acetaldehyde and Guerbet reaction of methanol and ethanol,respectively.The acidity and the alkalinity as well as the surface copper species of catalysts were characterized by NH 3/CO 2-TPD,XPS,H 2-TPR and H 2-TPD techniques.The results show that the catalytic performance of Guerbet reaction of methanol and ethanol is related to the surface Cu 0 species and the number of moderate basic sites.Increasing the specific surface area of Cu 0 is beneficial to the dehydrogenation of methanol and ethanol to formaldehyde and acetaldehyde.The increase of the amount of moderate basic sites can promote the condensation reaction of formaldehyde and acetaldehyde.