Thermodynamic analysis of molecular simulations of N                         2                          and O                         2                          adsorption on zeolites under plateau special conditions

Yaoguo Fu; Yingshu Liu; Xiong Yang; Ziyi Li; Lijun Jiang; Chuanzhao Zhang; Haoyu Wang; Ralph T. Yang

doi:10.1016/j.apsusc.2019.03.011

Thermodynamic analysis of molecular simulations of N ₂ and O ₂ adsorption on zeolites under plateau special conditions

Yaoguo Fu
, Yingshu Liu
, Xiong Yang
, Ziyi Li
, Lijun Jiang
, Chuanzhao Zhang
, Haoyu Wang
, Ralph T. Yang

Department of Chemical and Biological Engineering

University of Science and Technology Beijing
Beijing Union University

Research output: Contribution to journal › Article › peer-review

43 Scopus citations

Abstract

Adsorption thermodynamics of N ₂ and O ₂ on two most commonly used zeolites (5A and Li-LSX) under plateau special conditions of wide ranges of temperature (238–298 K) and pressure (0–300 kPa) for pressure swing adsorption (PSA) oxygen production were studied based on molecular simulations and theoretical model fitting. Adsorption isotherms for each adsorbate-adsorbent pair at different temperatures were fitted by Langmuir, Freundlich and Sips models, obtaining equilibrium parameters including adsorption capacity, strength, heterogeneity and N ₂ /O ₂ selectivity. Thermodynamic parameters such as Gibb's free energy, enthalpy, and entropy changes were numerically derived, and isosteric adsorption heats and distributions of potential energy were simulated. The results suggest that the adsorption capacity and affinity follow the order of N ₂ -Li-LSX > N ₂ -5A > O ₂ -5A > O ₂ -Li-LSX, leading to higher N ₂ /O ₂ selectivity on Li-LSX compared to 5A. For Li-LSX, N ₂ /O ₂ selectivity increases significantly with temperature above 273 K due to the difference in adsorption thermodynamics of N ₂ and O ₂ varying with temperature in terms of different adsorption heterogeneities. For 5A, the homogeneous distributions of N ₂ and O ₂ as well as the wide scopes of affinities from Na ⁺ and Ca ²⁺ exhibit N ₂ /O ₂ selectivity with negligible temperature dependence, which is beneficial for stable oxygen production with a fixed PSA process under large day-and-night temperature difference. This study provides theoretical basis for obtaining an optimal balance between efficiency and stability of oxygen production by using a proper mixture of Li-LSX and 5A.

Original language	English
Pages (from-to)	868-875
Number of pages	8
Journal	Applied Surface Science
Volume	480
DOIs	https://doi.org/10.1016/j.apsusc.2019.03.011
State	Published - Jun 30 2019

Keywords

Adsorption heterogeneity
Adsorption thermodynamics
Molecular simulation
PSA oxygen production
Zeolites

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10.1016/j.apsusc.2019.03.011

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Fu, Y., Liu, Y., Yang, X., Li, Z., Jiang, L., Zhang, C., Wang, H., & Yang, R. T. (2019). Thermodynamic analysis of molecular simulations of N ₂ and O ₂ adsorption on zeolites under plateau special conditions Applied Surface Science, 480, 868-875. https://doi.org/10.1016/j.apsusc.2019.03.011

@article{bfd4ac9519774d1e88cab3863cdc976b,

title = " Thermodynamic analysis of molecular simulations of N 2 and O 2 adsorption on zeolites under plateau special conditions ",

abstract = " Adsorption thermodynamics of N 2 and O 2 on two most commonly used zeolites (5A and Li-LSX) under plateau special conditions of wide ranges of temperature (238–298 K) and pressure (0–300 kPa) for pressure swing adsorption (PSA) oxygen production were studied based on molecular simulations and theoretical model fitting. Adsorption isotherms for each adsorbate-adsorbent pair at different temperatures were fitted by Langmuir, Freundlich and Sips models, obtaining equilibrium parameters including adsorption capacity, strength, heterogeneity and N 2 /O 2 selectivity. Thermodynamic parameters such as Gibb's free energy, enthalpy, and entropy changes were numerically derived, and isosteric adsorption heats and distributions of potential energy were simulated. The results suggest that the adsorption capacity and affinity follow the order of N 2 -Li-LSX > N 2 -5A > O 2 -5A > O 2 -Li-LSX, leading to higher N 2 /O 2 selectivity on Li-LSX compared to 5A. For Li-LSX, N 2 /O 2 selectivity increases significantly with temperature above 273 K due to the difference in adsorption thermodynamics of N 2 and O 2 varying with temperature in terms of different adsorption heterogeneities. For 5A, the homogeneous distributions of N 2 and O 2 as well as the wide scopes of affinities from Na + and Ca 2+ exhibit N 2 /O 2 selectivity with negligible temperature dependence, which is beneficial for stable oxygen production with a fixed PSA process under large day-and-night temperature difference. This study provides theoretical basis for obtaining an optimal balance between efficiency and stability of oxygen production by using a proper mixture of Li-LSX and 5A.",

keywords = "Adsorption heterogeneity, Adsorption thermodynamics, Molecular simulation, PSA oxygen production, Zeolites",

author = "Yaoguo Fu and Yingshu Liu and Xiong Yang and Ziyi Li and Lijun Jiang and Chuanzhao Zhang and Haoyu Wang and Yang, \{Ralph T.\}",

note = "Publisher Copyright: {\textcopyright} 2019 Elsevier B.V.",

year = "2019",

month = jun,

day = "30",

doi = "10.1016/j.apsusc.2019.03.011",

language = "English",

volume = "480",

pages = "868--875",

journal = "Applied Surface Science",

issn = "0169-4332",

publisher = "Elsevier B.V.",

}

Fu, Y, Liu, Y, Yang, X, Li, Z, Jiang, L, Zhang, C, Wang, H & Yang, RT 2019, ' Thermodynamic analysis of molecular simulations of N ₂ and O ₂ adsorption on zeolites under plateau special conditions ', Applied Surface Science, vol. 480, pp. 868-875. https://doi.org/10.1016/j.apsusc.2019.03.011

Thermodynamic analysis of molecular simulations of N ₂ and O ₂ adsorption on zeolites under plateau special conditions . / Fu, Yaoguo; Liu, Yingshu; Yang, Xiong et al.
In: Applied Surface Science, Vol. 480, 30.06.2019, p. 868-875.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - Thermodynamic analysis of molecular simulations of N 2 and O 2 adsorption on zeolites under plateau special conditions

AU - Fu, Yaoguo

AU - Liu, Yingshu

AU - Yang, Xiong

AU - Li, Ziyi

AU - Jiang, Lijun

AU - Zhang, Chuanzhao

AU - Wang, Haoyu

AU - Yang, Ralph T.

PY - 2019/6/30

Y1 - 2019/6/30

N2 - Adsorption thermodynamics of N 2 and O 2 on two most commonly used zeolites (5A and Li-LSX) under plateau special conditions of wide ranges of temperature (238–298 K) and pressure (0–300 kPa) for pressure swing adsorption (PSA) oxygen production were studied based on molecular simulations and theoretical model fitting. Adsorption isotherms for each adsorbate-adsorbent pair at different temperatures were fitted by Langmuir, Freundlich and Sips models, obtaining equilibrium parameters including adsorption capacity, strength, heterogeneity and N 2 /O 2 selectivity. Thermodynamic parameters such as Gibb's free energy, enthalpy, and entropy changes were numerically derived, and isosteric adsorption heats and distributions of potential energy were simulated. The results suggest that the adsorption capacity and affinity follow the order of N 2 -Li-LSX > N 2 -5A > O 2 -5A > O 2 -Li-LSX, leading to higher N 2 /O 2 selectivity on Li-LSX compared to 5A. For Li-LSX, N 2 /O 2 selectivity increases significantly with temperature above 273 K due to the difference in adsorption thermodynamics of N 2 and O 2 varying with temperature in terms of different adsorption heterogeneities. For 5A, the homogeneous distributions of N 2 and O 2 as well as the wide scopes of affinities from Na + and Ca 2+ exhibit N 2 /O 2 selectivity with negligible temperature dependence, which is beneficial for stable oxygen production with a fixed PSA process under large day-and-night temperature difference. This study provides theoretical basis for obtaining an optimal balance between efficiency and stability of oxygen production by using a proper mixture of Li-LSX and 5A.

AB - Adsorption thermodynamics of N 2 and O 2 on two most commonly used zeolites (5A and Li-LSX) under plateau special conditions of wide ranges of temperature (238–298 K) and pressure (0–300 kPa) for pressure swing adsorption (PSA) oxygen production were studied based on molecular simulations and theoretical model fitting. Adsorption isotherms for each adsorbate-adsorbent pair at different temperatures were fitted by Langmuir, Freundlich and Sips models, obtaining equilibrium parameters including adsorption capacity, strength, heterogeneity and N 2 /O 2 selectivity. Thermodynamic parameters such as Gibb's free energy, enthalpy, and entropy changes were numerically derived, and isosteric adsorption heats and distributions of potential energy were simulated. The results suggest that the adsorption capacity and affinity follow the order of N 2 -Li-LSX > N 2 -5A > O 2 -5A > O 2 -Li-LSX, leading to higher N 2 /O 2 selectivity on Li-LSX compared to 5A. For Li-LSX, N 2 /O 2 selectivity increases significantly with temperature above 273 K due to the difference in adsorption thermodynamics of N 2 and O 2 varying with temperature in terms of different adsorption heterogeneities. For 5A, the homogeneous distributions of N 2 and O 2 as well as the wide scopes of affinities from Na + and Ca 2+ exhibit N 2 /O 2 selectivity with negligible temperature dependence, which is beneficial for stable oxygen production with a fixed PSA process under large day-and-night temperature difference. This study provides theoretical basis for obtaining an optimal balance between efficiency and stability of oxygen production by using a proper mixture of Li-LSX and 5A.

KW - Adsorption heterogeneity

KW - Adsorption thermodynamics

KW - Molecular simulation

KW - PSA oxygen production

KW - Zeolites

UR - https://www.scopus.com/pages/publications/85062685743

U2 - 10.1016/j.apsusc.2019.03.011

DO - 10.1016/j.apsusc.2019.03.011

M3 - Article

AN - SCOPUS:85062685743

SN - 0169-4332

VL - 480

SP - 868

EP - 875

JO - Applied Surface Science

JF - Applied Surface Science

ER -

Fu Y, Liu Y, Yang X, Li Z, Jiang L, Zhang C et al. Thermodynamic analysis of molecular simulations of N ₂ and O ₂ adsorption on zeolites under plateau special conditions Applied Surface Science. 2019 Jun 30;480:868-875. doi: 10.1016/j.apsusc.2019.03.011

Thermodynamic analysis of molecular simulations of N ₂ and O ₂ adsorption on zeolites under plateau special conditions

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