Elucidating the Copper–Hägg Iron Carbide Synergistic Interactions for Selective CO Hydrogenation to Higher Alcohols

Abstract

CO hydrogenation to higher alcohols (C2+OH) provides a promising route to convert coal, natural gas, shale gas, and biomass feedstocks into value-added chemicals and transportation fuels. However, the development of nonprecious metal catalysts with satisfactory activity and well-defined selectivity toward C2+OH remains challenging and impedes the commercialization of this process. Here, we show that the synergistic geometric and electronic interactions dictate the activity of Cu0–χ-Fe5C2 binary catalysts for selective CO hydrogenation to C2+OH, outperforming silica-supported precious Rh-based catalysts, by using a combination of experimental evidence from bulk, surface-sensitive, and imaging techniques collected on real and high-performance Cu–Fe binary catalytic systems coupled with density functional theory calculations. The closer is the d-band center to the Fermi level of Cu0–χ-Fe5C2(510) surface than those of χ-Fe5C2(510) and Rh(111) surface, and the electron-rich interface of Cu0–χ-Fe5C2(510) due to the delocalized electron transfer from Cu0 atoms, facilitates CO activation and CO insertion into alkyl species to C2-oxygenates at the interface of Cu0–χ-Fe5C2(510) and thus enhances C2H5OH selectivity. Starting from the CHCO intermediate, the proposed reaction pathway for CO hydrogenation to C2H5OH on Cu0–χ-Fe5C2(510) is CHCO + (H) → CH2CO + (H) → CH3CO + (H) → CH3CHO + (H) → CH3CH2O + (H) → C2H5OH. This study may guide the rational design of high-performance binary catalysts made from earth-abundant metals with synergistic interactions for tuning selectivity.

Iron‐Based Fischer‐Tropsch Catalysts for Higher Alcohol Synthesis

“…These references fall into two groups: references lacking of detailed selectivity information, displayed as stars in Fig. (e.g., , ), and references that were lacking of information concerning conversion. These data could therefore not be displayed in Fig.…”

Highly Dispersed Ni–Fe Alloy Catalysts on MgAl2O4 Derived from Hydrotalcite for Direct Ethanol Synthesis from Syngas

“…[ 16,22 ] Metal iron has been widely applied in the hydrogenation of CO to higher alcohols, which enables the dissociative adsorption of CO and promote carbon chain growth. [ 22–24 ] Considering the mechanism of DES reaction, associating Fe with a second active site for CO insertion reaction is critical for alcohol formation. Recent research on Ni‐containing catalysts suggested that nickel had a strong ability for CO insertion and therefore promoted the formation of higher alcohols.…”

Single-pass transformation of syngas into ethanol with high selectivity by triple tandem catalysis

“…The design of a single catalyst with different functionalities to enable only a single reaction channel is very difficult. Although much effort has been devoted to designing bi-or multi-component catalysts such as Rh-Mn, Rh-Fe, Cu-Co and Cu-Fe catalysts, the ethanol selectivity is lower than 60% even at limited CO conversions (Supplementary Table 1) [12][13][14][15][16][17][18][19] .…”