Impact of Pd:Pt ratio of Pd/Pt bimetallic catalyst on CH4 oxidation

• Published in: Applied catalysis. B, Environmental Environmental, 2022-11, Vol.316, p.121623, Article 121623
• Main Authors: Park, Jiseok, Kim, Dongjoon, Byun, Sang Woo, Shin, Hyeonwoo, Ju, Yanggeun, Min, Haehyun, Kim, Young Jin, Heo, Iljeong, Hazlett, Melanie J., Kim, Minkyu, Kang, Sung Bong
• Format: Article
• Language: English
• Subjects: DFT calculation; Exhaust environment; Methane oxidation; Pd:Pt ratio
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2022.121623

Bimetallic Pd/Pt catalysts have recently attracted considerable attention in controlling emission control of methane. Here, we show the impact of Pd/Pt ratio (1:0, 9:1, 3:1, 1:1, 1:3, 1:9, 0:1) on the catalytic methane oxidation under simulated exhaust environments from the CH4-rich to -lean feed. Under dry feed conditions, the CH4 oxidation activity was linear to the Pd:Pt ratio, where the Pd-only (1:0) exhibited the best performance. However, under wet feed conditions containing 5% of water vapor, bimetallic Pd/Pt catalysts having a small fraction of Pt showed superior overall activities in a wide range of reaction environments. The interaction of Pd-Pt, forming active PdO-Pt pair sites, was confirmed by a series of analysis such as STEM-EDS, XPS and H2-TPR. The evidence by DFT calculations relates the distinct properties of bimetallic Pd/Pt sites to (i) stable CH4 adsorption, (ii) facile C–H bond cleavage and (iii) weaker adsorption of water on Pt site. [Display omitted] •Comprehensive CH4 oxidations were examined with various Pd:Pt ratio.•Small substitution of Pt to Pd-only remarkably enhances catalytic performance.•The Pd-Pt bimetallic catalyst forms active PdO-Pt pair site and metallic Pt site.•PdO-Pt site exhibits strong adsorption to methane and facile C-H bond cleavage.•Facile H2O desorption on PtPd catalyst also enhances H2O resistance.