LaCuZnX (X=Al, Zr, Al+Zr) perovskite-like catalysts treated by NaBH4 and their catalytic performance for CO2 hydrogenation to methanol

Abstract

La:Cu:Zn:X (X=Zr, Al, Al+Zr) perovskite-like catalysts were prepared by coprecipitation method followed by liquid phase reduction by NaBH4. The physicochemical properties of the catalysts were tested by a series of characterization methods, and the catalysts were tested for methanol synthesis from CO2 hydrogenation in a fixed-bed reactor. The results showed that the as-prepared catalysts were mainly composed of La2CuO4 perovskite-like crystal structure and doping of elements led to the spatial distortion of the perovskite-like structure. After reduction by NaBH4, metal copper species and some high-valence copper species were found, which could be further reduced during the reaction. The CO2 conversion was positively correlated with the Cu surface area, the dispersion of Cu, and the (Cuα++Cu0)/Cutotal of the catalyst. The higher methanol selectivity was obtained when Cuα+ binding energy was farther away from Cu+ binding energy. LCZA had the highest CO2 conversion, LCZ catalyst possessed the highest methanol selectivity, and LCZZA catalyst presented the optimal methanol space time yield.