Regulating Oxygen Vacancies for Enhanced Higher Oxygenate Synthesis via Syngas

Abstract

Constructing highly efficient dual active sites for preferential formation of higher oxygenates via direct syngas conversion remains a grand challenge. Herein, we reported that the regulation of oxygen vacancy density of metal–oxide support could effectively promote the production of oxygenates. Compared with an inert SiO2-supported Co-based catalyst, the rutile TiO2-supported catalyst with abundant oxygen vacancies exhibited up to 44.7% CO conversion with the selectivity and space–time yield (STY) of the oxygenate increased to 43.4 wt % and 50 mg gcat. –1 h–1, respectively. Further studies established a nearly linear relationship between the density of the oxygen vacancy and the atomic ratio of Co2+/Co0 or the STY of oxygenated products. Characterization confirmed that the oxygen vacancies not only promote CO adsorption, dissociation, and subsequently the carburization of cobalt species to form Co2C but also create a C-rich and H-poor local microchemical environment that benefits CO associative adsorption and CO bond insertion to form oxygenates. The synergistic effect of oxygen vacancies and the Co0/Co2C interface site contributed to the observed enhanced performance for direct syngas conversion to higher oxygenates.

Oxygen Vacancy over CoMnOx Catalysts Boosts Selective Ethanol Production in the Higher Alcohol Synthesis from Syngas

“…EPR characterization was also tested and is shown in Figure S5. A symmetrical signal with a g value of 2.004 was detected for all spent catalysts, which confirmed the existence of oxygen vacancies . The intensity of the EPR signal represents the density of oxygen vacancies, and the changing trend of different samples is consistent with the fitted results of the O 1s XPS spectra.…”

“…A symmetrical signal with a g value of 2.004 was detected for all spent catalysts, which confirmed the existence of oxygen vacancies. 39 The intensity of the EPR signal represents the density of oxygen vacancies, and the changing trend of different samples is consistent with the fitted results of the O 1s XPS spectra. The C 1s XPS spectra was fitted at 284 and 284.8 eV, which are attributed to the carbide species of Co 2 C and −(CH 2 ) n −, respectively, 17,40,41 further suggesting the formation of carbides during the reaction.…”

Control of metal–support interaction for tunable CO hydrogenation performance over Ru/TiO2 nanocatalysts

“…10–13 The application of the SMSI effect in enhancing catalytic reactivity and product selectivity of a metal catalyst has been commonly reported for CO hydrogenation toward long-chain hydrocarbons. 14–18 Zhang et al reported that the activity in FTS shows a volcano-like trend with increasing reduction temperature from 200 to 600 °C. 14 Such a variation in activity is characterized as being related to the as-formed metal–support interface, in which the TiO x overlayer at Ru/TiO 2 interfaces promotes CO dissociation.…”