Decomposition of carbon dioxide hydrate in the samples of natural coal with different degrees of metamorphism

Publication date: Available online 15 July 2019Source: Chinese Journal of Chemical EngineeringAuthor(s): Vyacheslav G. Smirnov, Valeriy V. Dyrdin, Andrey Yu. Manakov, Zinfer R. IsmagilovAbstractMethane and carbon dioxide hydrates are one of the possible forms in which these gases exist in natural coal. In this work, the decomposition of carbon dioxide hydrate in five samples of natural coal differing from each other in metamorphism degree was investigated experimentally. Carbon dioxide hydrate dispersed in coals was sinthesized from water adsorbed in these coals. During a linear temperature rise in an autoclave with the coal + hydrate sample the hydrate decomposition manifests itself as a step of increase in gas pressure, accompanied by a decrease/stabilization of the temperature of coal sample. The dependencies of the amount of hydrate formed on initial coal humidity and on gas pressure during hydrate formation were studied. It was demonstrated that each coal sample is characterized by its own humidity threshold below which hydrate formation in natural coal is impossible. With an increase in gas pressure, the amount of water transformed into hydrate increases. For the studied coal samples, the decomposition of carbon dioxide hydrates proceeds within a definite temperature and pressure range, and this range is close to the curve of phase equilibrium for bulk hydrate.

Source: Chinese Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research