Electron Regulation of Single Indium Atoms at the Active Oxygen Vacancy of In₂O₃(110) for Production of Acetic Acid and Acetone through Direct Coupling of CH₄ with CO₂

Abstract

The production of acetic acid and acetone from the direct coupling of CO2 and CH4 on the doped In2O3(110) surface has been studied by extensive first‐principles calculations, and the Ga or Al substitution for the single In atom at the active oxygen vacancy of In2O3(110) can stabilize the reaction species and reduce the free energy barrier of the rate‐limiting C−H activation for the conversion of CO2 and CH4 to acetic acid. Herein, the metal doping lowers the energy level of partially empty s and p orbitals of In1 at the oxygen vacancy site and manipulates its electronic properties, resulting in the activity improvement. The stable intermediate with the newly‐formed CH3COO* has the available In1 site for subsequent CH4 activation, which may initiate the direct C−C coupling of CH3COO* and CH3* to yield C3 species on the doped In2O3(110). These findings suggest that the metal doping of the active oxygen vacancy opens an avenue for the carbon‐chain growth through heterogeneously catalytic coupling of CO2 and CH4.

Rational Design of Metal-Alkoxide-Functionalized Metal–Organic Frameworks for Synergistic Dual Activation of CH4 and CO2 toward Acetic Acid Synthesis

“…Experimentally, a number of heteroge- neous catalysts were examined such as Cu−Co-based catalyst, 9 M/SiO 2 (M = Pd and Rh), 10 Co−Pd/TiO 2 , 11 Fe/ZnO, 12 Cumodified ZSM-5, 13 Zn-modified H-ZSM-5, 14 and montmorillonite (MMT) supported oxides (ZnO, CeO 2 , MnO 2 −ZnO, CeO 2 −MnO 2 , and CeO 2 −ZnO). 15 Computationally, density functional theory (DFT)-guided mechanistic understanding and catalyst design were conducted over a series of heterogeneous catalysts such as ZnO (1010), Cu/ZnO (1010), and Fe/ZnO (1010) surfaces, 12 CeO 2 (111) and ZnO (1010) surfaces, 15 Au(I)-ZSM-5, 16 Cu(111) surface, 17 Zn-doped ceria, 18 (ZnO) 3 −In 2 O 3 interface, 19 M-exchanged MFI zeolites (M = Be, Co, Cu, Mg, Mn, Zn), 20 Cu-modulated BEA, MFI, MOR, and TON zeolites, 21 Zn-modified H-ZSM-5, 22 MFI zeolite, 23 undoped/doped In 2 O 3 (110) surfaces, 24 and dual sites on CeO 2 (110) surfaces. 25 For CH 4 + CO 2 = CH 3 COOH, the catalytic cycle generally involves CH 4 activation and dissociation, C−C coupling between CH 3 anion and gaseous/activated CO 2 , proton transfer for CH 3 COOH formation, and desorption of CH 3 COOH from the catalyst.…”

Enabling heterogeneous catalysis to achieve carbon neutrality: Directional catalytic conversion of CO2 into carboxylic acids

“…In addition, Ga/Al-doped In 2 O 3 or single atom/frustrated Lewis pair dual sites are predicted as highly active catalysts for direct conversion of CO 2 and CH 4 into acetic acid due to their promoting effect in C-C coupling with CH 3 * and CO 2 * as stabilized intermediates. 150,151 In general, the effective development of the catalysts has not been well established. It is highly desirable for focusing on the mechanisms of understanding and constructing active sites with intelligent consideration.…”

“…CH 3 * has been pointed out as the key intermediate for acetic acid. In addition, Ga/Al‐doped In 2 O 3 or single atom/frustrated Lewis pair dual sites are predicted as highly active catalysts for direct conversion of CO 2 and CH 4 into acetic acid due to their promoting effect in C‐C coupling with CH 3 * and CO 2 * as stabilized intermediates 150,151 . In general, the effective development of the catalysts has not been well established.…”

CO2 Hydrogenation to Methanol and Ethanol on In2O3-Based Single-Atom Catalysts and a New Scaling Relation

“…Currently, the catalytic conversion of CO 2 into high-value products has been extensively studied due to the demand for the natural carbon cycle and sustainable development. Since CO 2 is a stable molecule, the key for the conversion is to develop effective, stable, and selective catalysts. − Indium oxide (In 2 O 3 ) has attracted increasing attention for its good ability in adsorption and activation of the CO 2 molecule. − Compared with the traditional Cu–Zn–Al catalysts, In 2 O 3 -based catalysts exhibit superior activity and selectivity to methanol. , So far, most In 2 O 3 -related works focus on the production of methanol, while higher ethanol, which possesses even higher energy density, has received less attention. − In 2021, Ye et al explored the CO 2 reduction reaction (CO 2 RR) to ethanol using the bifunctional Ir 1 /In 2 O 3 single-atom catalyst (SAC) and achieved >99% ethanol selectivity with an excellent turnover frequency (TOF) . A Lewis acid–base pair model composed of a single Ir atom and adjacent oxygen vacancy was proposed to explain the adsorption and activation of the CO 2 molecule .…”