Effect of Preparation Method on the Performance of Cu-Mn-(La)-Zr Catalysts for CO2 Hydrogenation to Methanol

A series of Cu-Mn-(La)-Zr catalysts with molecular ratios of 6 : 3 : (0.35) : 1 was synthesized by sol-gel (CMLZ-S), co-precipitation (CML-CP, CMLZ-CP) and hydrothermal (CMLZ-H) methods, respectively. The effects of the Mn and La on the activity of catalysts were investigated. It was found that the addition of La promoted the formation of the medium basic sites. Mn acted as an electronic promotor that transfer electrons through redox reactions, causing other metals to exhibit different valence states, thus promoting the adsorption and activation of H-2 and CO2. At a certain temperature, methanol selectivity decreased in the order of CMLZ-H>CMLZ-S>CMLZ-CP>CMZ-CP. The selectivity of methanol is correlated with the distribution of basic sites. For the CMLZ-H catalyst, the highest percentage of moderate basic sites facilitated the activation of CO2, resulting in the highest selectivity of methanol. The CO2 conversion was correlated with the Cu specific surface area.

Automated summary

A series of Cu-Mn-(La)-Zr catalysts were synthesized using sol-gel, co-precipitation, and hydrothermal methods, and the effects of Mn and La on their activity were investigated. It was found that the addition of La promoted the formation of medium basic sites, while Mn acted as an electronic promotor that enhanced the adsorption and activation of H-2 and CO2.