Monometallic iron catalysts with synergistic Na and S for higher alcohols synthesis via CO2 hydrogenation

Abstract

Direct hydrogenation of CO2 to higher alcohols is highly attractive and challenging. Iron catalysts are generally not regarded as ideal candidates, owing to its poor ability for non-dissociative CO activation, and needs to combine with other metals (such as Rh, Pd, Cu) for above process. Herein, we proposed an iron catalyst co-modified with Na and S (FeNaS-0.6), achieving a space-time yield of 80.5 mg gcat−1 h−1 for alcohols, more than 98 % of which corresponds to C2+ alcohols. The synergistic effects of Na and S enable the monometallic iron catalyst to provide matched molecularly adsorbed CO and alkyl species simultaneously required for higher alcohols synthesis. Sulfur existed in the form of sulfate, and its electron-withdrawing effects could transfrom the surrounding Fe sites for CO dissociation to those for non-dissociative CO adsorption. The DFT modeling also confirmed more facile formation of alcohols on the Na and S co-modified iron catalyst.