Chinese Journal of Catalysis ›› 2025, Vol. 74: 97-107.DOI: 10.1016/S1872-2067(25)64718-8

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Benefits of H-ZSM-5 zeolite from fluoride-mediated acidic synthesis for liquid-phase conversion of cyclohexanol

Qisong Yia,b,1, Lu Lina,1, Huawei Genga, Shaohua Chenc, Yuanchao Shaoa, Ping Hea, Zhifeng Liua, Haimei Xua, Tiehong Chenc, Yuanshuai Liua,*(), Valentin Valtcheva,d,*()   

  1. aShandong Energy Institute, Qingdao Energy Shandong Laboratory, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Science, Qingdao 266101, Shandong, China
    bUniversity of Chinese Academy of Sciences, Beijing 100049, China
    cKey Laboratory of Advanced Energy Materials Chemistry, Institute of New Catalytic Materials Science, Nankai University, Tianjin 300350, China
    dUniversité de Caen Normandie, ENSICAEN, CNRS, LCS, 14000 Caen, France
  • Received:2025-01-10 Accepted:2025-04-01 Online:2025-07-18 Published:2025-07-20
  • Contact: *E-mail: liuys@qibebt.ac.cn (Y. Liu), valentin.valtchev@ensicaen.fr (V. Valtchev).
  • About author:1Contributed equally to this work.
  • Supported by:
    National Natural Science Foundation of China(22109167);National Natural Science Foundation of China(22479152);Natural Science Foundation of Shandong Province(2022HWYQ-088);Taishan Scholars Program(tsqn202211260)

Abstract:

The hydrothermal stability of zeolites is essential for their potential applications in biomass conversion, especially in processes involving elevated temperatures alongside the use or generation of H2O. In this study, we employed F- ions as mineralizers to synthesize hydrothermally stable ZSM-5 zeolites under acidic conditions. The acidic synthesis system promotes zeolites with fewer silanol-terminated lattice defects (ZSM-5(A)) compared to the traditional basic conditions (ZSM-5(B)), endowing materials with substantially higher structural integrity and hydrophobicity. After 10 days of autoclave treatment at 200 °C in aqueous phase, H-ZSM-5(A) demonstrated nearly unchanged reaction rates in the dehydration of cyclohexanol, while H-ZSM-5(B) lost > 50% of the dehydration activity. Additionally, H-ZSM-5(A) delivered higher initial dehydration rates compared to H-ZSM-5(B). The different measured activation energies further revealed variations in reaction pathways during cyclohexanol dehydration, i.e., the monomer- or dimer-mediated routes depending on the concentration of alcohol molecule within zeolite pores, providing additional evidence for the strengthened hydrophobic nature of H-ZSM-5(A). Beyond this, the zeolite surface properties and the strength of cyclohexanol-zeolite interactions may impose additional transport/adsorption barriers attributed to multi-phase phenomena on the more polar H-ZSM-5(B) zeolite surfaces. More importantly, the hydrothermal treatment did not induce significant desilication and dealumination in H-ZSM-5(A), thereby preserving its active acid sites and ensuring exceptional hydrothermal stability. The present work fundamentally studies the synthesis of hydrothermally stable zeolites in an acidic medium using fluorides and expands the understanding of polar interactions in catalysis, characterized by the dehydration of cyclohexanol, for future application in biomass conversion.

Key words: Biomass conversion, Dehydration, Hydrothermal stability, Kinetics, Zeolites