Simulation of the adsorption behavior of CO2 / N2 / O2 and H2O molecules in lignite

被引：0

作者：

Cheng G. ^{[1
,2
,3
]}

Li Y. ^{[1
]}

Zhang M. ^{[1
]}

Cao Y. ^{[4
]}

机构：

[1] College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo

[2] Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization, Jiaozuo

[3] Henan Key Laboratory of Coal Green Transformation, Jiaozuo

[4] School of Chemical Engineering, Zhengzhou University, Zhengzhou

来源：

Meitan Xuebao/Journal of the China Coal Society | 2021年 / 46卷

关键词：

adsorption; CO[!sub]2[!/sub; density functional theory; giant canonical Monte Carlo; lignite;

D O I：

10.13225/j.cnki.jccs.FX21.0673

中图分类号：

学科分类号：

摘要：

In order to investigate the adsorption mechanism of N2,O2,CO2,H2O molecules on oxygen⁃containing func⁃ tional groups (OFGs) of lignite,the density functional theory (DFT) and grand canonical Monte Carlo (GCMC) sim⁃ ulation method were used to study the electrostatic potential (ESP) of OFGs,the adsorption energy of H2O,N2,O2, CO2 molecules and OFGs,and the adsorption isotherms,isosteric adsorption heat,diffusion coefficients of N2,O2,CO2 in lignite.The results show that the order of the maximum ESP of each OFG is Ph—OH>Ph—COOH>R—COOH>R—OH>Ph(R)—C =O>R2—C =O>Ph—O—R>R—O—R;the order of the minimum ESP is Ph—O—R>Ph—OH> R—O—R>Ph—COOH>R—COOH>R2—C =O>Ph(R)—C =O>R—OH.The adsorption energy calculation results show that the adsorption stability of H2O and OFGs is greater than that of N2,O2,and CO2.Double hydrogen bonds ex⁃ ist between H2O and —COOH,resulting the adsorption stability of H2O and —COOH is more stable than that of H2O and —OH,—O—,—C =O.For—OH and —O— groups,the O atom is easy to act as the hydrogen bond receptor when it is not connected to the benzene.Compared with —OH,—O— and —C =O,—COOH has the strongest ad⁃ sorption capacity for CO2,O2 and N2.Except for R2—C =O and Ph—OH,the absolute value of adsorption energy of CO2 and each OFG is greater than that of O2;except for R—O—R,the absolute value of the adsorption energy of O2 and each OFG is greater than that of N2.The relationship between the adsorption amount of gas molecules in lignite is CO2>O2>N2 at the same pressure and temperature;the adsorption capacity of gases decreases at 298 K to 348 K.The adsorption isotherms of the three gases in the lignite structure model are in good agreement with Langmuir adsorp⁃ tion model.At the temperature of 298 K,323 K,and 348 K,the isosteric adsorption heat of CO2 is between 31 - 32 kJ/ mol,and the isosteric adsorption heats of O2 and N2 are between 18-20 kJ/ mol.Molecular dynamics calculation results show that the diffusion coefficient (D) of CO2,O2,N2 molecules in the lignite structure model is 1.0×10-5,8. 78×10-5 and 1.17×10-4 cm2 / s,respectively. © 2021 China Coal Society. All rights reserved.

引用

页码：960 / 969

页数：9

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