Atom‐Economical Synthesis of Dimethyl Carbonate from CO₂: Engineering Reactive Frustrated Lewis Pairs on Ceria with Vacancy Clusters

Abstract

The chemical conversion of CO2 to long‐chain chemicals is considered as a highly attractive method to produce value‐added organics, while the underlying reaction mechanism remains unclear. By constructing surface vacancy‐cluster‐mediated solid frustrated Lewis pairs (FLPs), the 100 % atom‐economical, efficient chemical conversion of CO2 to dimethyl carbonate (DMC) was realized. By taking CeO2 as a model system, we illustrate that FLP sites can efficiently accelerate the coupling and conversion of key intermediates. As demonstrated, CeO2 with rich FLP sites shows improved reaction activity and achieves a high yield of DMC up to 15.3 mmol g−1. In addition, by means of synchrotron radiation in situ diffuse reflectance infrared Fourier‐transform spectroscopy, combined with density functional theory calculations, the reaction mechanism on the FLP site was investigated systematically and in‐depth, providing pioneering insights into the underlying pathway for CO2 chemical conversion to long‐chain chemicals.

Revealing the Crystal Facet Effect of Ceria in Pd/CeO2 Catalysts toward the Selective Oxidation of Benzyl Alcohol

“…Pd/CeO 2 –C exhibits two components with lifetimes of 155 (τ 1 ) and 290 ps (τ 2 ). According to the recent theoretical result reported by Li et al, the τ 2 component could be ascribed to defects with small sizes such as Ce 3+ -oxygen vacancy associates. The above results agree with previous studies , proposing that oxygen vacancies on the surfaces of the CeO 2 (111) and (100) facets tend to be present in the form of large-size clusters and small-size defects, respectively.…”

CeO2 Frustrated Lewis Pairs Improving CO2 and CH3OH Conversion to Monomethylcarbonate

“…To verify the effective CO 2 and CH 3 OH activation over FLP, we exploited their reactivity to form monomethylcarbonate (MMC), by studying the CO 2 /CH 3 OH chemical interaction with the CeO 2 surface previously saturated with methoxide (CH 3 O–CeO 2 ) or carbonate (CO 3 –CeO 2 ) species, respectively. The presence of Ce 3+ alone should indeed hamper MMC formation, , while clustered Ce 3+ /V O forming an FLP is expected to improve the CO 2 reactivity . A preliminary comparison between CO 3 -MW­(650) and CH 3 O – MW­(650) (taken for simplicity as reference spectra) and the spectral differences of CO 3 –CeO 2 after CH 3 OH adsorption (Figures a and S19a) indicated a consumption of b-CO 3 = and hCO 3 – species and formation of methoxide vibrations.…”

“…The presence of Ce 3+ alone should indeed hamper MMC formation, 29,30 while clustered Ce 3+ /V O forming an FLP is expected to improve the CO 2 reactivity. 32 A preliminary comparison between CO 3 -MW(650) and CH 3 O − MW(650) (taken for simplicity as reference spectra) and the spectral differences of CO 3 −CeO 2 after CH 3 OH adsorption (Figures 7a and S19a after m-OCH 3 consumption are covered by t-OCH 3 species. 19 In parallel to MMC band formation, we observed the growth of three bands at around 1360, 1630, and 2942 cm −1 related to formate (HCOO − ).…”

“…As first formulated by Jung and Bell, the reaction usually exploits both acid and base Lewis sites over an amphoteric catalyst such as ZrO 2 , CeO 2 , or their solid solutions. Several studies showed that the presence of oxygen vacancies, induced by Zr doping of CeO 2 , could promote CO 2 activation through carbonate formation and directly improving DMC production. − Considering that pure CeO 2 oxygen vacancies formed over (110) planes were predicted to form more easily bidentate carbonates however, the presence of Ce 3+ in CeO 2 was also directly related to catalyst deactivation. − Recently, Li and co-workers reported that FLP at CeO 2 improved DMC formation . The catalytic tests indicated a higher DMC yield for the highly reduced ceria (Ce 3+ ≈ 19%), while density functional theory (DFT) modeling predicted that the Ce 3+ -to-CO 2 charge transfer decreased the CO 2 activation energy.…”

Vacancy-cluster-mediated surface activation for boosting CO2 chemical fixation

“…This provides important support for understanding the catalytic reaction process and determining the active site of the reaction. [20][21][22] Herein, we focus our attention on layered metal oxyhalide MOX (M = Fe, Bi; X = Cl, Br, I), whose heterogeneous structure with alternating [M 2 O 2 ] 2+ and halogen layers might enable the presence of electron-donor and -acceptor units in a confined region. [23][24][25][26] Although halogens are considered to be robust nucleophilic species for attacking electrophilic carbon atom of epoxy ring, the halogen-terminated surface of MOX would inhibit the exposure of metal atoms serving as electron-acceptor units.…”