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Title: Methane capture at room temperature: adsorption on cubic d-MoC and orthorhombic b-Mo2C molybdenum carbide (001) surfaces
Author: Posada Pérez, Sergio
Politi, José Roberto S.
Viñes Solana, Francesc
Illas i Riera, Francesc
Keywords: Teoria del funcional de densitat
Density functionals
Issue Date: 2015
Publisher: Royal Society of Chemistry
Abstract: Based on periodic Density Functional Theory (DFT) calculations, carried out using a standard generalized gradient approximation type exchange-correlation functional including or not a van der Waals dispersive forces, the ability of the cubic δ-MoC(001) surface to capture methane at room temperature is suggested. Adsorption on the orthorhombic β-Mo2C(001) surfaces, with two possible terminations, has been also considered and, in each case, several molecular orientations have been tested with one, two, or three hydrogen atoms pointing towards the surface on all high-symmetry adsorption sites. The DFT results indicate that the δ-MoC(001) surface shows a better affinity towards CH4 than β-Mo2C(001). The calculated adsorption energy values on δ-MoC(001) surface are larger, and hence better, than on other methane capturing materials such as metal organic frameworks. Besides, the theoretical desorption temperature values estimated from the Redhead equation indicate that methane would desorbs at 330 K when adsorbed on the δ-MoC(001) surface, whereas this temperature is lower than 150 K when the adsorption involves β-Mo2C(001). Despite of this, adsorbed methane presents a very similar structure compared to the isolated molecule, due to a weak molecular interaction between the adsorbate and the surface. Therefore, the activation of methane molecule is not observed, so these surfaces are, in principle, not recommended as possible methane dry reforming catalysts.
Note: Versió postprint del document publicat a:
It is part of: RSC Advances, 2015, vol. 5, p. 33737-33748
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ISSN: 2046-2069
Appears in Collections:Articles publicats en revistes (Ciència dels Materials i Química Física)

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