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Issue 16, 2017
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The effect of potassium on steam-methane reforming on the Ni4/Al2O3 surface: a DFT study

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Abstract

Steam-methane reforming is a method of converting natural gas to syngas, and the additive K could affect the activity of steam-methane reforming on Ni catalyst supported by Al2O3. In addition, K could release carbon deposition. In the present work, density functional theory calculations were performed to study the reaction mechanisms and catalytic activity of steam-methane reforming on clean and K pre-adsorbed Ni4 clusters supported by Al2O3. Adsorption situations and the reaction cycles for steam-methane reforming reactions on clean and K pre-adsorbed Ni4-Al2O3 clusters were clarified. The rate-limiting step is the dissociative adsorption of molecular methane. K will promote steam-methane reforming through donating electron density and enhancing the activity of Ni by enhancing the overlapping of the orbitals of Ni and C. As a result, the barriers of C–H cleavage in the first two steps of CH4 dissociation on K pre-adsorbed Ni4 clusters are lower than that on clean clusters and thus retain the activity of steam-methane reforming. On the contrary, the barriers of C–H cleavage in the last two steps of CH4 dissociation on K pre-adsorbed Ni4/Al2O3 are higher than that on clean Ni4/Al2O3 and thus K will relieve the carbon deposition, which is in good agreement with the experimental results.

Graphical abstract: The effect of potassium on steam-methane reforming on the Ni4/Al2O3 surface: a DFT study

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Publication details

The article was received on 18 May 2017, accepted on 21 Jul 2017 and first published on 21 Jul 2017


Article type: Paper
DOI: 10.1039/C7CY00986K
Citation: Catal. Sci. Technol., 2017,7, 3613-3625
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    The effect of potassium on steam-methane reforming on the Ni4/Al2O3 surface: a DFT study

    M. Li, Z. Lu and G. Wang, Catal. Sci. Technol., 2017, 7, 3613
    DOI: 10.1039/C7CY00986K

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