Promotion of Anatase/Rutile Junction to Direct Conversion of Syngas to Ethanol on the Rh/TiO2 Catalysts

Although significant efforts have been made for the direct syngas conversion to ethanol, ethanol yield remains low. Herein, we studied syngas conversion on the Rh/TiO2 catalysts with different TiO2 phase compositions. The ethanol selectivity and yield reached 34.9 and 19.4%, respectively, at a 55.7% CO conversion on the Rh/P25 catalyst. Among the supported single Rh catalysts, this is currently the highest reported ethanol yield. The catalyst also shows good stability. The mixture of anatase–rutile phases in the P25 promotes the electron transfer from P25 to Rh species because of the strong metal–support interaction. It boosts the Rh0 active site generation, the CO dissociation, and CHx species formation, which is the significant intermediate for ethanol formation. In contrast, the Rh supported on the pure phase anatase or rutile TiO2 presents poor ethanol yield, which mainly produces the Rh+ species. This study provides an effective method to improve the ethanol yield for direct syngas conversion.