One-step synthesis of hierarchically porous fly ash-based NaX zeolite as assisted by CTAB for low-concentration CO2 adsorption--颗粒学报PARTICUOLOGY

Wei, Y., Wu, H., Kong, H., Miao, Y., & Wang, P. (2025). One-step synthesis of hierarchically porous fly ash-based NaX zeolite as assisted by CTAB for low-concentration CO2 adsorption. Particuology, 97, 69-79. https://doi.org/10.1016/j.partic.2024.12.002

One-step synthesis of hierarchically porous fly ash-based NaX zeolite as assisted by CTAB for low-concentration CO₂ adsorption

Yao Wei^a, Hong Wu^b *, Haowen Kong^a, Yingju Miao^b, Ping Wang^b

a College of Environmental and Chemical Engineering, Dalian University, China
b College of Chemical and Materials Engineering, Liupanshui Normal University, China

https://doi.org/10.1016/j.partic.2024.12.002

Volume 97, February 2025, Pages 69-79

Received 1 October 2024, Revised 3 December 2024, Accepted 5 December 2024, Available online 20 December 2024, Version of Record 9 January 2025.

E-mail: hongwu@lpssy.edu.cn

Highlights

• One-step synthesis of hierarchically porous fly ash-based NaX zeolite for low-concentration CO2 adsorption.

• CTAB assisted synthesis of mesoporous and hierarchically porous zeolites with abundant and controllable mesopore.

• CTAB promotes mesopore formation and inhibits crystal growth during zeolite synthesis.

Abstract

Despite significant attention being drawn to the synthesis of zeolites from fly ash for CO₂ adsorption, few studies have focused on hierarchical porous NaX zeolites derived from fly ash. The existing synthesis methods are often complex, and the role of CTAB in zeolite formation remains unclear. To address these research gaps, we employed a one-step method for synthesizing hierarchically porous fly ash-based NaX zeolites with tunable mesoporosity. Utilizing CTAB as a template agent, we conducted a comprehensive investigation into the effects of varying CTAB dosages and aluminum source types on zeolite formation. The synthesized materials were fully characterized through XRD, FTIR, SEM, TEM, and N₂ adsorption/desorption analysis. The results showed that the mesoporous volume of the zeolites can be effectively controlled by adjusting the CTAB/Al₂O₃ ratio. At an optimal ratio of 0.04, the synthesized zeolite has a surface area of 422 m²/g and a mesoporous volume of 0.116 cm³/g, which represents a two-fold increase compared to the NaX synthesized without CTAB. This improvement of mesoporosity significantly reduces the resistance to CO₂ diffusion, thereby enhancing the adsorption performance with a maximum adsorption capacity of 3.37 mmol/g and a high cyclic stability. A further investigation reveals the crucial role of CTAB in promoting mesopore formation and inhibiting crystal growth during zeolite synthesis. These findings provide valuable insights into the one-step synthesis of hierarchical porous zeolites.

Graphical abstract

Keywords

One-step method; Fly ash; Hierarchical porous structure; NaX zeolite; CTAB

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