The Beneficial Effect of Hydrogen on CO Oxidation over Au Catalysts. A Computational Study

Molecules

Akhtar Hussain¹  Jose Gracia¹  J. W. Niemantsverdriet¹ 

[1] ¹Physics Division, Pakistan Institute of Science and Technology (PINSTECH), P. O. Nilore, Islamabad 44000, Pakistan ²Schuit Institute of Catalysis, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands ³Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands

关键词: PROX;    DFT;    gold;    CO oxidation;    adsorption;   

DOI  :  10.3390/molecules16119582

来源: mdpi

【 摘 要 】

Density functional theory calculations have been carried out to explore the effect of hydrogen on the oxidation of CO in relation to the preferential oxidation of CO in the presence of excess hydrogen (PROX). A range of gold surfaces have been selected including the (100), stepped (310) surfaces and diatomic rows on the (100) surface. These diatomic rows on Au(100) are very efficient in H-H bond scission. O₂ hydrogenation strongly enhances the surface-oxygen interaction and assists in scission of the O–O bond. The activation energy required to make the reaction intermediate hydroperoxy (OOH) from O₂ and H is small. However, we postulate its presence on our Au models as the result of diffusion from oxide supports to the gold surfaces. The OOH on Au in turn opens many low energy cost channels to produce H₂O and CO₂. CO is selectively oxidized in a H₂ atmosphere due to the more favorable reaction barriers while the formation of adsorbed hydroperoxy enhances the reaction rate.

【 授权许可】

CC BY   
This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.