Highly Selectively Methane Photooxidation to CH<sub>3</sub>OH and HCHO over an Integrated Fe<sub>2</sub>O<sub>3</sub>/WO<sub>3</sub> Heterojunction Greatly Promoted by Iron(III) Chloride
Wenhao Zhou, Yongqing Ma, Chuhong Zhu, Min Wang, Min Wang, Ganhong Zheng, Yilin Lu, Meiling Wang, Meiling Wang
Abstract
Realizing highly selective and efficient CH 4 conversion to CH 3 OH and HCHO can bring about both energy and environmental benefits and is of great significance for social development. Herein, an integrated Fe 2 O 3 /WO 3 heterojunction was established and used for CH 4 photooxidation to CH 3 OH and HCHO at ambient temperature. Under optimized experimental conditions, a high CH 3 OH + HCHO yield of 15.3 mmol g –1 h –1 was achieved with a high selectivity of 97.3%, outperforming most of the current reports so far as we know. This improved catalytic performance could be attributed to the synergy between the Fe 2 O 3 /WO 3 heterojunction and FeCl 3 in solution. Fe 3+ served as the electron acceptor and Fenton reactant and together with the formed heterojunction effectively improved carrier separation and ·OH generation. ·OH induced in situ formation of ·Cl. The formed ·Cl then activated CH 4 and produced chlorine-containing intermediates CH 3 Cl/CH 2 Cl 2, which ultimately resulted in the formation of CH 3 OH and HCHO through CH 3 Cl/CH 2 Cl 2 hydrolysis and effectively avoided overoxidation. This work demonstrated an effective strategy of converting CH 4 to CH 3 OH and HCHO without peroxidation.