The role of the acidity of alumina prepared by aluminum-carbon black composite for CO hydrogenation to dimethyl ether on hybrid Cu–ZnO–Al2O3/alumina

Abstract

The effects of surface area and the acidity of mesoporous γ-Al2O3, which is prepared by calcining aluminum-carbon black composite (Al/CB) of the precipitated aluminum nitrate on carbon black at different weight ratios, were investigated to verify the roles of carbon black in the surface properties and stability of Cu–ZnO–Al2O3 for the direct synthesis of dimethyl ether (DME) from syngas. A high surface area of ~100 m2/g with a large pore diameter of ~25 nm originated from the occupied spaces of carbon black enhanced the dispersion of the active Cu–ZnO–Al2O3 particles by forming a strong and stable interaction with mesoporous solid acid γ-Al2O3 surfaces. The enhanced dispersion of copper-containing particles, being strongly interacted with the acid sites of the hybrid Cu–ZnO–Al2O3/Al2O3 catalyst using γ-Al2O3 prepared at an optimal Al/CB weight ratio of 10, is mainly responsible for the high CO conversion with a high yield to oxygenates and a suppressed aggregation of active copper species during the direct synthesis of DME from syngas.