Ethanol synthesis from syngas on Mn- and Fe-promoted Rh/γ-Al2O3

The catalytic hydrogenation of CO was studied over Mn- and/or Fe-promoted Rh/γ-Al2O3 catalysts. The catalysts were characterized by means of XRD, BET, H2-TPR·H2-TPD, XPS and DRIFTS. CO hydrogenation results showed that the doubly Mn- and Fe-promoted Rh/γ-Al2O3 catalysts exhibited superior catalytic activity and better ethanol selectivity. The DRIFTS results showed that Mn promoter stabilized the adsorbed CO on Rh+ and Fe stabilized adsorbed CO on Rh+ and Rh0, especially Rh0. The fact that doubly Mn- and Fe-promoted Rh/γ-Al2O3 owned more (Rhx0–Rhy+)–O–Fe3+·(Fe2+) active species was proposed to be a crucial factor accounting for its higher ethanol selectivity.