Design of Single-Atom and Frustrated-Lewis-Pair dual active sites for direct conversion of CH4 and CO2 to acetic acid

Abstract

Direct conversion of CH4 and CO2 into acetic acid is an emerging attractive process but remains a significant challenge due to the inherent stability of both molecules. Hence, developing active and stable catalysts is crucial for the simultaneous activation of CO2 and CH4. Herein, we designed the “Single-Atom” - “Frustrated-Lewis-Pair” (SA-FLP) dual-active-site catalysts for the co-conversion of CH4 and CO2 to acetic acid based on density functional theory (DFT) calculations. The SA sites were introduced by doping the transition-metal (TM) atoms (TM = Fe, Co, Ni, Cu; Ru, Rh, Pd, Ag; Os, Ir, Pt, Au) into CeO2(110) surface, and the FLP sites were constructed by the regulation of surface oxygen vacancies. Our results demonstrate the introduction of SA into CeO2 surface could facilitate the formation of oxygen vacancies, and thus promotes the formation of FLP sites. The SA-FLP dual active sites can concurrently activate CH4 and CO2 with CH4 preferentially activated at SA sites and CO2 preferentially activated at FLP sites. Among the twelve SA-FLP catalysts, Ag1-FLP catalyst exhibits the best performance in the reaction of CH4 and CO2 to acetic acid with a rate-determining barrier of 1.12 eV and a turnover frequency of 2.52 × 10–3 s−1 at 573 K and 2 bar. This work not only offers a novel catalyst prototype for the co-conversion of CH4 and CO2 to acetic acid but also provides insights into developing dual-active-site catalysts on earth-abundant metal oxide materials.