Highly Dispersed K- and Pd-Comodified Fe Catalyst for CO₂ Hydrogenation to Higher Alcohols

Abstract

The conversion of CO2 to higher alcohols (HA) is a sustainable way for CO2 utilization, but the development of an efficient catalyst with multifunctional active sites to regulate the C–C coupling process remains a great challenge. Herein, we report a Fe catalyst modified with highly dispersed K and Pd for the efficient synthesis of HA. The optimal 0.3K-1Pd/Fe2O3 catalyst displays the best catalytic performance with an HA STY of 48 mg gcat –1 h–1 at 320 °C, 5 MPa, and 6 L gcat –1 h–1, which is 3.5 times that of 1Pd/Fe2O3 and 35 times that of the 0.3K/Fe2O3 catalyst. We found that in situ generated PdFe alloy and K synergistically stabilize the iron carbide phase, which is responsible for the CO dissociation and alkyl formation, while the PdFe alloy acts as an active site for CO nondissociative activation and CO insertion. Appropriate amounts of K and Pd can regulate the balance of CO* and CH x * species on the catalyst surface, which effectively facilitates C–C coupling to synthesize HA.

Development of Multifunctional Catalysts for the Direct Hydrogenation of Carbon Dioxide to Higher Alcohols

“…The study of CO 2 hydrogenation to higher alcohols can be traced back to the 1980s [ 43 ], but most catalysts are directly modified from the conversion of syngas to alcohols by hydrogenation. The problems of low activity and limited selectivity hinder its practical application in industry [ 44 ]. Due to the co-existence of various intermediates, the reaction mechanism for CO 2 hydrogenation to higher alcohols is still controversial.…”