Kinetics of Methane Hydrate Decomposition Studied via in Situ Low Temperature X-ray Powder Diffraction

Autor:	David J. Keffer, E. Andrew Payzant, S. Michelle Everett, Tommy J. Phelps, Derek L. Mull, Claudia J. Rawn
Rok vydání:	2013
Předmět:	Clathrate hydrate Temperature Analytical chemistry Water Atmospheric temperature range Decomposition Methane Arrhenius plot Kinetics Crystallography chemistry.chemical_compound chemistry Melting point Physical and Theoretical Chemistry Hydrate Powder Diffraction Powder diffraction
Zdroj:	The Journal of Physical Chemistry A. 117:3593-3598
ISSN:	1520-5215 1089-5639
DOI:	10.1021/jp4020178
Popis:	Gas hydrate is known to have a slowed decomposition rate at ambient pressure and temperatures below the melting point of ice. As hydrate exothermically decomposes, gas is released and water of the clathrate cages transforms into ice. Based on results from the decomposition of three nominally similar methane hydrate samples, the kinetics of two regions, 180-200 and 230-260 K, within the overall decomposition range 140-260 K, were studied by in situ low temperature X-ray powder diffraction. The kinetic rate constants, k(a), and the reaction mechanisms, n, for ice formation from methane hydrate were determined by the Avrami model within each region, and activation energies, E(a), were determined by the Arrhenius plot. E(a) determined from the data for 180-200 K was 42 kJ/mol and for 230-260 K was 22 kJ/mol. The higher E(a) in the colder temperature range was attributed to a difference in the microstructure of ice between the two regions.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::ef773e1a09537d3fb6f8404fa1e58d04 https://doi.org/10.1021/jp4020178 Zobrazit plný text záznamu