CO2-Induced Gate-Opening Adsorption on a Chabazite/Phillipsite Composite Zeolite Transformed from a Faujasite Zeolite Using Organic Structure-Directing Agent-Free Steam-Assisted Conversion

Yuto Higuchi; Sana Miyagawa; Yasunori Oumi; Satoshi Inagaki; Shunsuke Tanaka

doi:10.1021/acsami.3c07313

CO₂-Induced Gate-Opening Adsorption on a Chabazite/Phillipsite Composite Zeolite Transformed from a Faujasite Zeolite Using Organic Structure-Directing Agent-Free Steam-Assisted Conversion

ACS Appl Mater Interfaces. 2023 Aug 16;15(32):38463-38473. doi: 10.1021/acsami.3c07313. Epub 2023 Jul 24.

Authors

Yuto Higuchi¹, Sana Miyagawa¹, Yasunori Oumi², Satoshi Inagaki³, Shunsuke Tanaka^{1

4}

Affiliations

¹ Department of Chemical, Energy and Environmental Engineering, Faculty of Environmental and Urban Engineering, Kansai University, 3-3-35 Yamate-cho, Suita-shi, Osaka 564-8680, Japan.
² Organization for Research and Community Development, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
³ Division of Materials Science and Chemical Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
⁴ Organization for Research and Development of Innovative Science and Technology (ORDIST), Kansai University, 3-3-35 Yamate-cho, Suita-shi, Osaka 564-8680, Japan.

PMID: 37487143
DOI: 10.1021/acsami.3c07313

Abstract

Organic structure-directing agent-free steam-assisted conversion and Cs⁺ ion exchange were used to transform the faujasite (FAU)-type zeolite to the Cs⁺-type chabazite/phillipsite (CHA/PHI) composite zeolite. Compared with the pure PHI-type zeolite, the Cs⁺-type CHA/PHI zeolite showed gate-opening CO₂ adsorption behavior and good thermal stability. In situ powder X-ray diffraction (PXRD) of the CO₂ adsorption was measured to elucidate the mechanism for the gate-opening adsorption on the CHA/PHI zeolite. The Na⁺-type CHA/PHI zeolite did not show such adsorption behavior, and the PXRD pattern of the Na⁺-type CHA/PHI zeolite did not change with increasing CO₂ partial pressure, which suggests that this unique adsorption behavior was caused by the PHI framework transition or Cs⁺ ions moving in both the CHA and PHI frameworks. Furthermore, in situ Fourier-transform infrared spectra of CO₂ adsorption and CO₂ breakthrough measurement on the Cs⁺-type CHA/PHI zeolite suggest that the CHA and PHI frameworks in the CHA/PHI zeolite shared eight-membered-ring windows and that CO₂ molecules could easily diffuse from a CHA cage to a PHI framework. The ideal adsorbed solution theory was used to calculate the CO₂/N₂ separation selectivity for the Cs⁺-type CHA/PHI zeolite. At 298 and 318 K, the Cs⁺-type CHA/PHI composite zeolite showed a high CO₂/N₂ separation coefficient of >10,000 compared with other zeolites with high CO₂ adsorption capacity. Furthermore, the CO₂ working capacity was calculated for the Cs⁺-type CHA/PHI zeolite in both the pressure- and temperature-swing processes, and the results showed that the CHA/PHI composite zeolite could selectively separate CO₂ from the CO₂/N₂ gas mixtures released from power generation plants operating using these processes.

Keywords: CHA/PHI composite framework; Cs+ ion; chabazite (CHA) zeolite; framework transition; gate-opening adsorption; high CO2 selectivity; phillipsite (PHI) zeolite.