Enhanced catalytic performance for direct synthesis of dimethyl ether from syngas over a La2O3 modified Cu-ZrO2/γ-Al2O3 hybrid catalyst

Abstract

A series of hybrid catalysts were made by physically mixing Cu-ZrO₂ and γ-Al₂O₃, for former it was modified with different loadings of La₂O₃ prepared by co-precipitation method. The catalysts were characterized by BET, XRD, N₂O-adsorption, EXAFS, H₂-TPR, NH₃-TPD techniques and evaluated in the synthesis of dimethyl ether from syngas. The results show that La₂O₃ promoted catalysts displayed a significantly better catalytic performance compared with Cu-ZrO₂/γ-Al₂O₃ catalyst in CO conversion and DME selectivity, and the optimum catalytic activity was obtained when the content of La₂O₃ was 12 wt%. The characterizations reveal that high copper dispersion, facile reducibility of copper particles and appropriate amount of acidic sites are responsible for the superior catalytic performance.