Understanding Polyol Decomposition on Bimetallic Pt鈥揗o Catalysts鈥擜 DFT Study of Glycerol

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• 作者：Bin Liu ; Mingxia Zhou ; Maria K. Y. Chan ; Jeffrey P. Greeley
• 刊名：ACS Catalysis
• 出版年：2015
• 出版时间：August 7, 2015
• 年：2015
• 卷：5
• 期：8
• 页码：4942-4950
• 全文大小：561K
• ISSN：2155-5435

文摘

Catalytic dehydrogenation and C鈥揅 and C鈥揙 bond cleavage for glycerol decomposition on bimetallic Pt鈥揗o alloy model catalysts are studied using periodic density functional theory. The scaling relationship developed for monometallic systems for fast binding energy prediction has been tested and validated on both Pt-skin and Pt₃Mo-skin bimetallic surfaces. Using only the binding energies of atomic C and O for corresponding alloy surfaces, this simple relationship is shown to be an extremely efficient approach to speeding up the catalytic trend analysis for bimetallic alloy catalysts. Similar to Pt(111), it is found that the Pt-skin surface also favors dehydrogenation via C鈥揌 bond cleavage and faster C鈥揅 bond cleavage over C鈥揙 bond cleavage, but the overall activity decreases compared with pure Pt. On Pt₃Mo-skin surfaces, the overall reaction becomes much more exothermic, but Mo species significantly affect the selectivity by favoring the C鈥揙 bond cleavage. Thermodynamic analyses also predict that surface Mo species can be easily oxidized under typical reforming conditions, forming molybdate clusters and severely altering surface structures and potentially catalytic properties. Guided by experimental observations, this study also explores possible bifunctional characteristics for Pt鈥揗o bimetallic catalysts responsible for improved reforming activity and hydrogen production rates.