Synergistic effect of bimetallic RuPt/TiO <sub>2</sub> catalyst in methane combustion
Shi-Ying Cao, Fan Ye, Nini Zhang, Yanglong Guo, Yun Guo, Li Wang, Sheng Dai, Wangcheng Zhan
Abstract
Abstract Designing metal compounds based on their structure and chemical composition is essential in achieving desirable performance in methane oxidation, because of the synergistic effect between different metal elements. Herein, a bimetallic Ru–Pt catalyst on TiO 2 support (RuPt‐O/TiO 2 ) was prepared by in situ reduction followed by calcination in air. Compared with monometallic catalysts (Ru‐O/TiO 2 and Pt‐O/TiO 2 ), the synergistic effect of mixed metals endowed bimetallic catalysts with excellent stability and outstanding performance in methane oxidation, with a reaction rate of 13.9 × 10 –5 at 303 °C. The varied characterization results revealed that among the bimetallic catalysts, RuO 2 was epitaxially grown on the TiO 2 substrate owing to lattice matching between them, and part of the PtO x adhered to the RuO 2 surface, in addition to a single PtO x nanoparticle with 4 nm in size. Consequently, Pt mainly existed in the form of Pt 2+ and Pt 4+ and a small amount of zero valence in the bimetallic catalyst, prompting the adsorption and activation of methane as the first and rate‐controlling step for CH 4 oxidation. More importantly, the RuO 2 species provided additional oxygen species to facilitate the redox cycle of the PtO x species. This study opens a new route for structurally designing promising catalysts for CH 4 oxidation.