Precisely synergistic synthesis of higher alcohols from syngas over iron carbides

Highly efficient synthesis of higher oxygenates, especially higher alcohols, directly from syngas is promising, but it is also challenging because of the requirement of coordination between CO dissociative and non-dissociative sites. Monometallic iron catalysts have a competitive advantage because of better contact of dual sites to achieve high alcohol selectivity. Here, a remarkable oxygenate selectivity of 69.7 wt % was realized over a synergistic iron catalyst with a Ca promoter alongside an alcohol fraction of 86.4% in oxygenates. Multiple characterizations showed that 2 wt % Ca loading enabled the Ca-Fe catalyst to have high surface iron carbides with the proper Fe2C/(Fe5C2+Fe3C) ratio, which facilitated synergy of CO dissociation and non-dissociation. In situ surface reaction characterizations confirmed that the 2 wt % Ca-Fe catalyst had moderate activation ability to balance dissociative and non-dissociative activation of CO, which favored better cooperation of ∗CO and ∗CHx to form the ∗CHx-∗CO species, further promoting higher-alcohol formation.