O'Malley, Alexander James, Garcia Sakai, Victoria, Silverwood, Ian Philip, Dimitratos, Nikolaos ![]() ![]() |
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Abstract
The diffusion of methanol in zeolite HY is studied using tandem quasielastic neutron scattering (QENS) experiments and molecular dynamics (MD) simulations at 300-400 K. The experimental diffusion coefficients were measured in the range 2-5 x 10-10 m2s-1 and simulated diffusion coefficients measured in the range of 1.6-3.2 x 10-9 m2s-1. Activation energies were measured as 8.8 and 6.9 kJ mol-1using QENS and MD respectively. Differences may be attributed predominantly to the experimental use of a dealuminated HY sample, containing significant defects such as strongly adsorbing silanol nests, compared to a perfect simulated crystal containing only evenly distributed Brønsted acid sites. Experimental and simulated diffusivities measured in this study are lower than those obtained from those previously calculated in siliceous faujasite, due to methanol H-bonding to Brønsted acid sites as observed in the MD simulations. However, both experimental and simulated diffusivities were significantly higher than those obtained in NaX, due to the higher concentration of extraframework cations present in the previously studied faujasites.
Item Type: | Article |
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Date Type: | Publication |
Status: | Published |
Schools: | Chemistry Advanced Research Computing @ Cardiff (ARCCA) |
Subjects: | Q Science > QD Chemistry |
Publisher: | Royal Society of Chemistry |
ISSN: | 1463-9076 |
Date of First Compliant Deposit: | 3 June 2016 |
Date of Acceptance: | 16 May 2016 |
Last Modified: | 22 Nov 2024 07:00 |
URI: | https://orca.cardiff.ac.uk/id/eprint/91126 |
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