Tandem reductive hydroformylation: A mechanism for selective synthesis of straight-chain α-alcohols by CO₂ hydrogenation

The direct conversion of CO₂ into linear α-alcohols (C₃₊ alcohol) in high yields is challenging because of the complexity arising from multiple competitive reactions. No studies have yet elucidated why CO₂ hydrogenation preferentially produces straight-chain C₃₊ alcohols rather than branched alcohols over metal oxide catalysts. In this study, we propose a new insight into the existence of tandem reductive hydroformylation as a mechanism for enhancing linear alcohol formation. We demonstrated a Na-promoted bimetallic Cu and Fe catalyst (Na–CuFe) that generated a C₃₊ alcohol-rich product (36.3 % of total products, 72.2 % of total alcohols) at a CO₂ conversion of 14.2 %. The Na–CuFe catalyst developed Cu and Fe₅C₂ for the reverse water gas shift (RWGS) and Fischer–Tropsch synthesis (FTS) sites, respectively. The low Fe content resulted in the development of a Cu–Fe₅C₂ active interface. Operando in situ investigation demonstrated high CO owing to active RWGS reaction boosted chain growth for C₃₊ alcohols. Density functional theory (DFT) simulation indicated the preferred CHO insertion over CO for C–C coupling. Thus, the Cu–Fe₅C₂ interface promotes the hydroformylation of on-site-generated intermediate via FTS and subsequent reduction of C₃₊ aldehydes to their corresponding C₃₊ alcohols.