One-pot synthesis of mesoporous Cu–γ-Al2O3 as bifunctional catalyst for direct dimethyl ether synthesis

Mesoporous copper–alumina (Cu–Al2O3) with different copper contents was synthesized in a one-pot reaction via the evaporation-induced self-assembly of Pluronic P123 and the corresponding metal precursors in ethanolic solution in the presence of nitric acid. Mesoporous Cu–Al2O3 calcined at 400 °C exhibits a large BET surface area of 265 m2/g and a pore volume of 0.48 cm3/g. XRD results indicate that the wall of mesoporous Cu–Al2O3 calcined at 400 °C is amorphous, and that it is transformed to crystalline material by further thermal treatment at 800 °C. Copper was formed as very small particles in the composite under 5% H2 flow at high temperature. Moreover, the mesoporous structure did not collapse after the sample was reduced at 650 °C for 4 h, and the copper particles with sizes of around 6 nm were well distributed through the entire mesoporous γ-Al2O3 network. Using the mesoporous Cu/γ-Al2O3 as a bifunctional catalyst for one-step dimethyl ether synthesis from synthesis gas, a CO conversion of 72% and a DME selectivity of 69% were obtained at 50 bar and 310 °C.

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► Mesoporous Cu–Al2O3 was synthesized in a one-pot reaction.
► The obtained Cu/γ-Al2O3 exhibits high activity in the one-step DME synthesis.
► Notably, this bifunctional catalyst is highly active without ZnO.