CuZnAlOOH catalysts with Cu0/Cu+ constructed by two-step hydrolysis for ethanol production from syngas

In this study, a CuZnAlOOH catalyst with adjustable Cu0/Cu+ ratios is successfully prepared by two-step hydrolysis, affording two catalysts with different morphologies. By embedding Cu0 grains on an oxide flake, a typical hydrogen spillover structure is formed, which is favorable for the hydrogenation of intermediates, with the production of a high number of hydrocarbons. On the other hand, by wrapping Cu0 grains in an oxide, hydrogenation is inhibited, and γ-AlOOH and Cu/γ-AlOOH sites are exposed. Ethanol synthesis over the two sites is different from that over the active sites of Cu0 grains embedded on a flake oxide. An approximate linear relationship exists between the mole ratio of CuZngel/(CuZnsolution + CuZngel) and that of surface Cu0/(Cu0 + Cu+). At CuZn gel/(solution + gel) ratios of 1/2–1/3, corresponding to the Cu0/(Cu0 + Cu+) ratios of 0.277–0.358, ethanol is produced in most advantage, the distribution of which is up to 55.5%.