Silica grain catalysis of methanol formation

Goumans, T P M, Wander, Adrian, Catlow, C Richard A and Brown, Wendy A (2007) Silica grain catalysis of methanol formation. Monthly Notices of the Royal Astronomical Society, 382 (4). 1829 - 1832. ISSN 0035-8711

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Abstract

The specific catalytic effect of a silica grain on the formation of methanol via the sequential addition of H atoms to CO adsorbed on the surface is investigated. A negatively charged defect on a siliceous edingtonite surface is found to reduce the gas phase barriers for the H + COads and H + H2C=O-ads reactions by 770 and 399 K, respectively, when compared to the same reactions in the gas phase. The catalytic effect of negatively charged surface sites could also be applicable to the hydrogenation of other adsorbed unsaturated species. However, the activation energies on the surface defect are still too large (1150 and 2230 K) for CH3OH to form efficiently at 10-20 K in the interstellar medium via a classical mechanism. It is therefore suggested that quantum mechanical tunnelling through the activation barrier is required for these hydrogen addition reactions to proceed at such temperatures. The calculations show that because the adsorption energies of CO and H2C=O on the negatively charged defect are substantial, CH3OH may form efficiently during the warm-up period in star-forming regions.

Item Type: Article
Keywords: astrochemistry, molecular processes, ISM : molecules, Interstellar dust grains, periodic model, solid CO, chemistry, surface, hydrogenation, formaldehyde, functionals, universe, mantles
Schools and Departments: School of Life Sciences > Chemistry
Subjects: Q Science
Depositing User: Deeptima Massey
Date Deposited: 22 Jul 2014 08:58
Last Modified: 07 Mar 2017 17:17
URI: http://sro.sussex.ac.uk/id/eprint/48680

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