Thermodynamic analysis of the difference in adsorption characteristics of CH4 and CO2 on continental shale

In order to explain the difference in adsorption characteristics of CH4 and CO2 on continental shale from the perspective of thermodynamics, the isothermal adsorption experiments of CH4 and CO2 adsorbed by shale in Yanchang Formation in Ordos Basin were carried out, and the excess adsorption capacit...

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Main Authors: Pei Xue, Quansheng Liang, Chao Gao, Jintao Yin, Shiyan Hao, Qianping Zhao
Format: Article
Language:English
Published: Frontiers Media S.A. 2023-02-01
Series:Frontiers in Earth Science
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/feart.2023.1139981/full
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author Pei Xue
Quansheng Liang
Chao Gao
Jintao Yin
Shiyan Hao
Qianping Zhao
author_facet Pei Xue
Quansheng Liang
Chao Gao
Jintao Yin
Shiyan Hao
Qianping Zhao
author_sort Pei Xue
collection DOAJ
description In order to explain the difference in adsorption characteristics of CH4 and CO2 on continental shale from the perspective of thermodynamics, the isothermal adsorption experiments of CH4 and CO2 adsorbed by shale in Yanchang Formation in Ordos Basin were carried out, and the excess adsorption capacity was corrected to absolute adsorption capacity. Then the Clausius-Clapeyron equation was used to analyze the isosteric heat of adsorption of CH4 and CO2 on shale. The results show that, for calculating the absolute adsorption capacity, Ozawa empirical formula or Van der Waals approximation method should be used to calculate the adsorption phase density. The absolute adsorption capacity should be selected as the basic data for calculating the isosteric heat of adsorption. The reason is that the excess isosteric heat of adsorption has a negative value in the low adsorption capacity stage, which is contradictory to the fact that the adsorption process is exothermic, and is significantly higher than the absolute isosteric heat of adsorption. There is a good linear positive correlation between the isosteric heat of adsorption and the adsorption amount of CH4 and CO2 adsorbed by continental shale, and the isosteric heat of adsorption of CH4 is greater than that of CO2. The absolute initial isosteric heat of adsorption of CH4 and CO2 adsorbed by shale is 52.04 kJ/mol and 27.71 kJ/mol, indicating that the adsorption force of CH4 on Yanchang Formation shale is stronger than that of CO2.
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spelling doaj.art-92c9f130c4ae46c59f6b603ba0914c452023-02-08T04:54:22ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632023-02-011110.3389/feart.2023.11399811139981Thermodynamic analysis of the difference in adsorption characteristics of CH4 and CO2 on continental shalePei XueQuansheng LiangChao GaoJintao YinShiyan HaoQianping ZhaoIn order to explain the difference in adsorption characteristics of CH4 and CO2 on continental shale from the perspective of thermodynamics, the isothermal adsorption experiments of CH4 and CO2 adsorbed by shale in Yanchang Formation in Ordos Basin were carried out, and the excess adsorption capacity was corrected to absolute adsorption capacity. Then the Clausius-Clapeyron equation was used to analyze the isosteric heat of adsorption of CH4 and CO2 on shale. The results show that, for calculating the absolute adsorption capacity, Ozawa empirical formula or Van der Waals approximation method should be used to calculate the adsorption phase density. The absolute adsorption capacity should be selected as the basic data for calculating the isosteric heat of adsorption. The reason is that the excess isosteric heat of adsorption has a negative value in the low adsorption capacity stage, which is contradictory to the fact that the adsorption process is exothermic, and is significantly higher than the absolute isosteric heat of adsorption. There is a good linear positive correlation between the isosteric heat of adsorption and the adsorption amount of CH4 and CO2 adsorbed by continental shale, and the isosteric heat of adsorption of CH4 is greater than that of CO2. The absolute initial isosteric heat of adsorption of CH4 and CO2 adsorbed by shale is 52.04 kJ/mol and 27.71 kJ/mol, indicating that the adsorption force of CH4 on Yanchang Formation shale is stronger than that of CO2.https://www.frontiersin.org/articles/10.3389/feart.2023.1139981/fullcontinental shaleisothermal adsorptionexcess adsorption capacityabsolute adsorption capacityisosteric heat of adsorption
spellingShingle Pei Xue
Quansheng Liang
Chao Gao
Jintao Yin
Shiyan Hao
Qianping Zhao
Thermodynamic analysis of the difference in adsorption characteristics of CH4 and CO2 on continental shale
Frontiers in Earth Science
continental shale
isothermal adsorption
excess adsorption capacity
absolute adsorption capacity
isosteric heat of adsorption
title Thermodynamic analysis of the difference in adsorption characteristics of CH4 and CO2 on continental shale
title_full Thermodynamic analysis of the difference in adsorption characteristics of CH4 and CO2 on continental shale
title_fullStr Thermodynamic analysis of the difference in adsorption characteristics of CH4 and CO2 on continental shale
title_full_unstemmed Thermodynamic analysis of the difference in adsorption characteristics of CH4 and CO2 on continental shale
title_short Thermodynamic analysis of the difference in adsorption characteristics of CH4 and CO2 on continental shale
title_sort thermodynamic analysis of the difference in adsorption characteristics of ch4 and co2 on continental shale
topic continental shale
isothermal adsorption
excess adsorption capacity
absolute adsorption capacity
isosteric heat of adsorption
url https://www.frontiersin.org/articles/10.3389/feart.2023.1139981/full
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