Estimation of adsorption of ethane on the superactive microporous carbon adsorbent using the theory of volume filling of
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Estimation of adsorption of ethane on the superactive microporous carbon adsorbent using the theory of volume filling of micropores A. E. Grinchenko,a E. E. Men´shchikova,a,b I. E. Men´shchikov,a A. V. Shkolin,a and A. A. Fomkina aA.
N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Science, Build. 4, 31 Leninsky prosp., 119071 Moscow, Russian Federation. E-mail: [email protected] bLyceum of the National Research University Higher School of Economics, 4 Bol´shoi Khariton´evskii per., 101000 Moscow, Russian Federation Using the main statements of the Dubinin theory of volume filling of micropores (TVFM) the amount of adsorbed ethane was estimated at pressures up to 4 MPa in the temperature range lower and higher than the critical temperature (303—333 K) on the superactive microporous carbon adsorbent with the bimodal micropore size distribution and a total micropore volume of 1.44 cm3 g–1. Two approaches were applied for comparison of the accuracy of calculations: the approach based on the calculation of "standard states" of adsorption and pressure and the approach taking into account the property of linearity of adsorption isosteres of gases in broad ranges of thermodynamic parameters. Both thermodynamic approaches showed good agreement of the results with experimental data and can be recommended for precalculations of adsorption equilibria of gases and vapors on the basis of the minimum physicochemical information about the adsorbent and adsorptive. The high agreement of the experimental and calculated data provides the basis for using the adsorption characteristics obtained in the framework of the TVFM for the calculation of differential molar isosteric heats of adsorption. Key words: adsorption, ethane, carbon adsorbents, theory of volume filling of micropores.
The recovery of ethane widely used for polyethylene fabrication is an important task under the modern conditions of growing volumes of oil, gas condensate, and natural gas production.1 Ethane is a basis of the large-scale production of polyethylene in the modern chemical industry. The ethane content in natural gas is low attaining2 14 vol.%. The ethane content in the casing-head gas reaches3 20 vol.%. High-selective technologies are needed for ethane recovery. Currently, rectification, adsorption, or membrane separation are the most used technologies to recover casing-head ethane. New nanoporous carbon adsorbents with high adsorption activity can be promising for increasing the efficiency of the adsorption method of ethane recovery from a mixture of hydrocarbons of various origin.4,5 It seems reasonable to use active carbons for ethane separation, because the energy of adsorption of ethane on the carbon adsorbent surface (~18 kJ mol–1) is substantially higher than the energy of adsorption of methane, which is the major component of the natural gas (~12 kJ mol–1).6 The efficiency of application of carbon adsorbents in the technologies of hydrocarbon separation, including those for the recovery of ethane, is ofte
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