Construction of Active Rh–TiO<sub><i>x</i></sub> Interfacial Sites on RhFeO<sub><i>x</i></sub>/P25 for Highly Efficient Hydrogenation of CO<sub>2</sub> to Ethanol
Chenfan Gong, Hao Wang, Jian Zhang, Chengguang Yang, Xianni Bu, Haiyan Yang, Jiong Li, Peng Gao
Abstract
Hydrogenation of CO 2 to ethanol is an efficient process for the utilization of CO 2 along with the production of value-added chemicals. However, CO 2 hydrogenation to ethanol is a complicated reaction, requiring the catalyst to activate CO 2 efficiently and accurately regulate the C–C coupling to achieve a high ethanol selectivity simultaneously. Herein, we report the synthesis of RhFeO x catalysts supported on TiO 2 with different crystal phase compositions (anatase, rutile, and P25), which were applied for the selective CO 2 hydrogenation to ethanol. The RhFeO x /P25 catalyst presented a high dispersion of Rh nanoparticles on the P25 support with abundant Rh 0 –Rh δ+ –O V –Ti 3+ (O V: oxygen vacancy) interfacial sites over the anatase/rutile junction. The optimized RhFeO x /P25 catalyst exhibited a high ethanol space–time yield of 18.7 mmol g cat –1 h –1 and a high Rh turnover frequency of 544.8 h –1 with 90.5% ethanol selectivity. An in-depth investigation via various ex situ and in situ characterizations as well as H 2 /D 2 exchange and C 2 H 4 pulse hydrogenation experiments demonstrated that the Rh 0 –Rh δ+ –O v –Ti 3+ interfacial sites played a crucial role in the conversion of CO 2 to ethanol. The surface Rh 0 sites facilitated the CO 2 activation and hydrogenation, while the Rh 0 –Rh δ+ –O v –Ti 3+ interfacial sites boosted the C–C coupling to produce ethanol. The high-performance RhFeO x /P25 catalyst also provides an attractive route for highly efficient ethanol synthesis via CO 2 hydrogenation.