Incorporating hierarchy into conventional zeolites for catalytic biomass conversions: A review

Wasim Khan, Xicheng Jia, Zhijie Wu, Jungkyu Choi, Alex C.K. Yip

    Research output: Contribution to journalReview articlepeer-review

    77 Citations (Scopus)

    Abstract

    Zeolites are promising catalysts that are widely used in petrochemical, oil, and gas industries due to their unique characteristics, such as ordered microporous networks, good hydrothermal stability, large surface area, tunable acidity, and shape-selectivity. Nevertheless, the sole presence of microporous channels in zeolites inevitably restricts the diffusion of bulky reactants and products into and out of the microporous networks, leading to retarded reaction rates or catalyst deactivation. This problem can be overcome by developing hierarchical zeolites which involve mesoporous and macroporous networks. The meso- and macro-porosities can enhance the mass transport of molecules and simultaneously maintain the intrinsic shape selectivity of zeolite microporosity. Hierarchical zeolites are mainly developed through post-synthesis and pre-synthesis or in situ modification of zeolites. In this review, we evaluated both pre-synthesis and post-synthesis modification strategies with more focus on post-synthesis modification strategies. The role of various synthesis strategies on the intrinsic properties of hierarchical zeolites is discussed. The catalytic performance of hierarchical zeolites in important biomass reactions, such as catalytic pyrolysis of biomass feedstock and upgradation of bio-oil, has been summarized. The utilization of hierarchical zeolites tends to give a higher aromatic yield than conventional zeolites with microporosity solely.

    Original languageEnglish
    Article number127
    JournalCatalysts
    Volume9
    Issue number2
    DOIs
    Publication statusPublished - 2019 Feb

    Bibliographical note

    Publisher Copyright:
    © 2019 by the authors. Licensee MDPI, Basel, Switzerland.

    Keywords

    • Biomass conversion
    • Deactivation
    • Hierarchical zeolite
    • Mesopores
    • Micropores
    • Synthesis

    ASJC Scopus subject areas

    • General Environmental Science
    • Catalysis
    • Physical and Theoretical Chemistry

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