Li+/ZSM-25 Zeolite as a CO2 capture adsorbent with high selectivity and Improved adsorption kinetics, showing CO2-induced framework expansion

Jianhua Zhao, Ke Xie, Ranjeet Singh, Gongkui Xiao, Qinfen Gu, Qinghu Zhao, Gang Li, Penny Xiao, Paul A. Webley

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14 Citations (Scopus)

Abstract

The structure of ZSM-25, a RHO family zeolite, was resolved recently. Recent reports focused on Na-ZSM-25 as a promising CO2 adsorbent with high CO2 working capacity and exceptional CO2/CH4 ideal selectivity for pressure swing adsorption. However, these reports discuss single-gas adsorption performance of Na-ZSM-25 and are unable to provide the CO2/CH4 separation behavior in practical scenarios where the adsorption is performed using mixed gases. Furthermore, Na-ZSM-25 suffers from slow adsorption kinetics that limits its industrial applications. In this study, Li+/ZSM-25 zeolites (LZZs) are developed to enhance the CO2 adsorption kinetics without compromising selectivity. The adsorption performance was examined using both single-(isotherm) and binary-(breakthrough) gas measurements. The results indicate that the CO2 adsorption rate of LZZ is 9.84 times that of Na-ZSM-25 with a simultaneous increase of the CO2 adsorption capacity by 6.1% at 303 K and 9.5 bar. The very high CO2/CH4 adsorptive selectivity is successfully inherited from Na-ZSM-25 zeolite in both single- and binary-gas adsorption. Furthermore, in situ XRD reveals CO2-induced framework expansion, which explains the origin of the high working capacity and type-II-like isotherms of the ZSM-25-based zeolites. This study implies promising application of LZZ in natural gas purification and biogas upgrading.

Original languageEnglish
Pages (from-to)18933-18941
Number of pages9
JournalJournal of Physical Chemistry C
Volume122
Issue number33
DOIs
Publication statusPublished - 23 Jul 2018
Externally publishedYes

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