Enhanced Catalytic Performance for Dimethyl Ether Synthesis from Syngas with the Addition of Zr or Ga on a Cu−ZnO−Al₂O₃/γ-Al₂O₃ Bifunctional Catalyst

Direct synthesis of dimethyl ether (DME) from synthesis gas was investigated on bifunctional catalysts, containing Cu−ZnO−Al 2 O 3 promoted with Zr or Ga on γ-Al 2 O 3 as a methanol dehydration catalyst. In comparison to an unpromoted bifunctional catalyst, promoted catalysts with Zr or Ga showed a higher catalytic performance and stability. The facile reducibility of copper particles with high dispersion and an appropriate acidity and electronic state of copper species are mainly responsible for the superior catalytic performance with the help of structural promoting effects of Ga or Zr components on Cu−ZnO−Al 2 O 3 . The high formation rate of methanol by CO hydrogenation on the Zr-promoted Cu−ZnO−Al 2 O 3 and the dehydration rate of methanol to DME on the modified acidic sites of γ-Al 2 O 3 are mainly responsible for the superior catalytic activity and stability.