Regulating Oxygen Vacancies for Enhanced Higher Oxygenate Synthesis via Syngas

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.