THERMAL SCIENCE

International Scientific Journal

ROLES OF ADSORPTION POTENTIAL AND SURFACE FREE ENERGY ON PURE CH4 AND CO2 ADSORPTION UNDER DIFFERENT TEMPERATURES

ABSTRACT
To fill the knowledge of adsorption characteristics of CH4 and CO2 associated with equilibrium and thermodynamics, adsorption equilibrium tests of pure gas on a coal were conducted under the different temperatures (35 °C, 50 °C, and 65°C by the static volumetric method. The equilibrium data were well matched by the SLD-PR model. The influence of some significant factors including temperature, pressure, adsorption potential and surface free energy on gas adsorption capacity were discussed. The results showed that the higher temperature (gas pressure) corresponds to the smaller (larger) adsorption capacity and the larger adsorption potential is, the smaller adsorption capacity is. Taking CH4 as adsorbent, the modified Langmuir equation can well match the SLD-PR model. However, when the adsorption medium is CO2, modified Freundlich equation is better. Using the two modified equations, we study further the relationship among the variation of surface free energy, its reduction rate and gas adsorption capacity. It can be concluded the larger the gas adsorption capacity is, the greater the reduction of surface free energy is, and the smaller the reduction rate of surface free energy is.
KEYWORDS
PAPER SUBMITTED: 2018-06-05
PAPER REVISED: 2018-09-10
PAPER ACCEPTED: 2018-11-10
PUBLISHED ONLINE: 2019-03-31
DOI REFERENCE: https://doi.org/10.2298/TSCI180605089X
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2019, VOLUME 23, ISSUE Supplement 3, PAGES [S747 - S755]
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© 2019 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International licence