The Determination of Shale Gas Absolute Adsorption Basing on Molecular Dynamics Simulation
Keywords:Shale gas, density of adsorbed phase, molecular simulation, absolute adsorption.
The adsorption experimental isotherms developed for excess adsorption of supercritical gases with the appearance of a distinct maximum and quick decrease cannot be explained with the base of the classic adsorption theory developed for absolute adsorption. The key of describing the adsorption of supercritical gases with classical adsorption theory is the correct conversion of the quantity of absolute adsorption and excess adsorption. According to Gibbs definition of adsorption, accurate evaluation of the adsorbed phase density is the key of the correct conversion of the quantity of absolute adsorption and excess adsorption. Based on the principle of molecular dynamics and the application of molecular simulation, it simulates the density of supercritical methane under 0 to 50 MPa, and the calculation results are in accordance with National Institute of Standards and Technology (NIST) data. Based on this, combined with the single molecular adsorption theory, it puts forward a new method of conversion of the quantity of absolute adsorption and excess adsorption that can be applied to a great range of pressure. This method has higher accuracy, and breaks through the existing conversion methods with limit of low pressure conditions.
He Yusheng, Li Zhong, Xi Hongxia, et al. Research process of gas-solid adsorption isotherms. J Ion Exchange and Adsorption 2004; 20(4): 376-381.
Li Wuguang, Yang Shenglai, Xu Jing, et al. A new model for shale adsorptive gas amount under a certain geological conditions of temperature and pressure. J Natural Gas Geoscience 2012; 23(4): 791-796
Rexer TFT, Benham MJ, Aplin AC, et al. Methane Adsorption on Shale under Simulated Geological Temperature and Pressure Conditions. J Energy and Fuels 2013; 27(6): 3099- 3109.
Zhang Zhiying and Yang Shengbo. On the adsorption and desorption trend of shale gas. J Journal of Experimental Mechanics 2012; 27(4): 492-496.
And PB and Chahine R. Modeling of High-Pressure Adsorption Isotherms above the Critical Temperature on Microporous Adsorbents: Application to Methane. J Langmuir 2016; 13(4): 808-813.
Guo Wei, Xiong Wei, Gao Shusheng ,et al . Isothermal adsorption/desorption characteristics of shale gas. Journal of Central South University(Science and Technology) 2013; 44(7): 2836-2840.
SW Zhou, HQ Xue, W Guo, B Lu and F Guo. Supercritical isothermal adsorption characteristics of shale gas based on gravimetric method. J 2016; 41(11): 2806-2812
Gas separation by adsorption processes M, Yang RT ,Wang Shusen, Zeng Meiyun, Hu Jinming Trans. Beijing, Chemical industry press1991.
Sheng Mao, Li Gensheng, Chen Liqiang, et al . Mechanisms analysis of shale-gas supercritical adsorption and modeling of isorption adsorption. J Journal of China Coal Society 2014; 39(S1): 179-183.
Zhou Yaping and Zhou Li. Study on the adsorption isotherms of supercritical hydrogen on activated carbon. J Acta Physico-Chimica Sinica 1997; 13(2): 119-127.
Ozawa S, Kusumi S and Ogino Y. Physical adsorption of gases at high pressure. J Colloid Interface Sci 1976; 56(1): 83-91. https://doi.org/10.1016/0021-9797(76)90149-1
Dubinin MM. The potential theory of adsorption of gases and vapors for adsorbents with energetically nonuniform surfaces. Chem Rev 1960; 60(2): 235-41. https://doi.org/10.1021/cr60204a006
Li M, Gu A, Lu X, et al . Determination of the adsorbate density from supercritical gas adsorption equilibrium data. J Carbon 2003; 41(3): 585-588. https://doi.org/10.1016/S0008-6223(02)00356-1
Xiong Jian, Liu Xiangjun, Liang Lixi, et al . Improved Dubibin- Astakhov model for shale-gas supercritical adsorption. J Acta Petrolei Sinaica 2015; 36(7): 849-856.
Sun Yan, Zhou Li, Sun Wei, et al . Impact of monolayer adsorption mechanism on hydrogen storage material. J Chinese Science Bulletin 2007; 52(3): 361-365.
Zhou Li. Supercritical adsorption study: confusion, problems and analysis C 2002.
Langmuir I. The constitution and fundamental properties of solids and liquids. Part II.—Liquids. Journal of the American Chemical Society 1915; 38(5): 125-126.
Li Z, Zhou Y, Bai S, et al. A Study on the Adsorption Isotherms in the Vicinity of the Critical Temperature. Adsorption-journal of the International Adsorption Society 2002; 8(2): 125-132. https://doi.org/10.1023/A:1020478301072
Zhou Y, Zhou L, Bai S, et al. Experimental Studies of the Generalized Adsorption Isotherm for the Supercritical Region. J Adsorption Science and Technology 2001; 19(8): 681-690. https://doi.org/10.1260/0263617011494493
Fu G and Zhou L. Measurement and analysis of methane adsorption isotherms on activated carbon. J Natural Gas Industry 2004; 24(1): 12+92-94.
Nijkamp MG, Raaymakers JEMJ, Dillen AJV, et al. Hydrogen storage using physisorption - materials demands. J Applied Physics A 2001; 72(5): 619-623. https://doi.org/10.1007/s003390100847
Xiao-Zhong C, Ya-Ping Z, Yu-Zhe Z, et al. Adsorption of hydrogen isotopes on micro- and mesoporous adsorbents with orderly structure. J Journal of Physical Chemistry B 2006; 110(45): 22596-600. https://doi.org/10.1021/jp064745o
Xue GW, Liu HF, Yao HF, et al. The types of tectonic coals and pore characters in Hancheng. J Journal of China Coal Society 2011; 36(36): 1845-1851.
Ambrose RJ, Hartman RC, Diaz-Campos M, et al. Shale Gas-in-Place Calculations Part I: New Pore-Scale Considerations. J Spe Journal 2012; 17(1): 219-229. https://doi.org/10.2118/131772-PA
Zhou L. Progress in Fundamental Research into Supercritical Adsorption and its Impact on Clean Energy Technology. J Adsorption Science and Technology 2009; 23(7): 509-518. https://doi.org/10.1260/026361705775212484
Cao TT, Song ZG, Wang S B, et al. A comparative study of the specific surface area and pore structure of different shales and their kerogens. J Chinese Science: Earth Science 2015; 58(4): 510-522. https://doi.org/10.1007/s11430-014-5021-2