The effect of CuO–ZnO–Al2O3 catalyst structure on the ethanol synthesis from syngas

CuO–ZnO–Al2O3 catalysts were prepared by complete liquid phase technology with different addition sequences. The results indicated that the catalyst prepared by the addition of (C3H7O)3Al to Cu(NO3)2 and Zn(NO3)2 solutions shows excellent ethanol selectivity at the initial stages of reaction, reaching approximately 40%. X-ray photoelectron spectroscopy results showed that ethanol synthesis requires a higher Cu+ content and higher Cu/Zn ratio on the catalyst surface. The temperature-programmed reduction test revealed strong interactions between Cu species and zinc or aluminum oxide. The increase in the difficulty of catalyst reduction indicated higher ethanol selectivity.

► The CuO–ZnO–Al2O3 catalysts have been prepared by the complete liquid-phase technology.
► Different addition sequences of CuO–ZnO–Al2O3 catalysts show different activities for ethanol synthesis.
► The synthesis of ethanol needs both higher Cu+ content on surface Cu species and higher Cu/Zn ratio.
► The more difficult is the reduction of the catalyst, the higher the selectivity of ethanol.