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Syngas Segregation Induced by Confinement in Carbon Nanotubes: A Combined First-Principles and Monte Carlo Study

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journal contribution
posted on 31.12.2009, 00:00 by Jing Guan, Xiulian Pan, Xin Liu, Xinhe Bao
A theoretical study combining first-principles and Monte Carlo simulations has been carried out to investigate the interactions of H2 and CO molecules with carbon nanotube (CNT) surfaces. The results show that there are stronger interactions of both H2 and CO with the interior nanotube surface than with the exterior surface. In addition, CO interacts more strongly with CNT surfaces than H2. This can be explained by the nature of the molecules and the different electronic properties of the concave and convex surfaces of CNTs formed by graphene layers. As a result, syngas molecules are enriched inside CNTs and the enrichment generally becomes greater in smaller nanotubes. Furthermore, the ratio of CO/H2 inside CNTs increases with respect to the composition of syngas in the exterior gas phase. The enriched reactants and altered CO/H2 ratio inside nanotubes could be beneficial for the reaction rate and lead to modification of the product selectivity.