Catalytic Tandem CO2 Hydrogenation and Hydroformylation for High-Yield Synthesis of C2+ Alcohols

Abstract

CO₂ hydrogenation to C₂₊OH is highly attractive but remains a great challenge due to low C₂₊OH productivity and poor catalyst stability. Herein, we report efficient CO₂ hydrogenation to C₂₊OH over a Ni- and K-co-modified Fe-based catalyst (1Ni-4K/Fe), achieving a promising space-time yield (STY) of 317.0 mg/g/h and catalytic stability over 300 h. Systematic investigations reveal that the addition of Ni promotes the formation of surface alkyl intermediates, while K mitigates the undesired deep hydrogenation of these alkyl intermediates. Both effects facilitate coupling between *CO and *CH_x, thereby enhancing the production of C₂₊OH. Moreover, the synergistic effect between K and Ni expedites the formation of Fe₅C₂ and the recarburization of in situ oxidized Fe species during the reaction, resulting in enhanced stability of the 1Ni-4K/Fe catalyst. Additionally, by introduction of Rh₁/POP (for the hydroformylation of olefins to aldehydes) and Cu@SiO₂ (for the hydrogenation of aldehydes to alcohols) catalysts to establish a 1Ni-4K/Fe||Rh₁/POPs||Cu@SiO₂ triple-tandem system, an excellent C₂₊OH STY of 980.5 mg/g/h can be achieved, along with a C₂₊OH selectivity of 55.0% and a high proportion of C₃₊OH (75.6%) in the alcohol products.