Structural properties and catalytic performance of the La-Cu-Zn mixed oxides for CO2 hydrogenation to methanol

A series of La-Cu-Zn-O mixed oxide catalysts were synthesized by a co-precipitation method and calcined under different temperatures. The XRD, BET, TPR, N2O-adsorption, XPS, SEM and TPD techniques were carried out to measure the aimed catalysts. The results indicated that the chemical environment of lanthanum element changes with the increase of calcination temperature. The La2CuO4 perovskite structure is obtained at the temperature higher than 823 K and the special copper species appear in the perovskites due to the special structure property. The catalysts with La2CuO4 perovskite structure show higher methanol selectivity compared with the mixed copper catalyst. For the perovskite catalysts, the conversion of CO2 changes with the same tendency of the copper species ratio (Cu alpha++Cu-0/Cu-Total%), which implied both Cu alpha+ and Cu-0 are important active sites in the perovskite catalyst for the reaction. (C) 2018 Published by Elsevier B.V. on behalf of Chinese Society of Rare Earths.