Cu–Mn–Al based catalyst for the direct syngas to dimethyl ether conversion

Cu–Mn–Al mixed oxides were prepared by calcination of carbonate layered double hydroxides. Four materials were prepared with nominal Cu/Mn ratios in the 0.5–2.0 range and 0.19 nominal Al atom fraction relative to metal ions. Reduction of the oxide precursors was followed by in situ X-ray absorption and X-ray diffraction and showed that copper was totally reduced, and manganese reduced mainly to Mn²⁺. Copper metal surface area by N₂O decomposition after in situ reduction showed that the dispersion increased with decreasing copper content in Mn–Cu–Al catalysts. In methanol synthesis from syngas, the methanol productivity and selectivity achieved values up to 35 mol kg⁻¹ h⁻¹ and 94% with Cu–Mn–Al catalysts. In the direct syngas to DME reaction, using γ-alumina as the methanol dehydration component, the productivity of the Cu–Mn–Al catalyst with 0.5 Cu/Mn ratio stood-out from that of the remaining catalysts.