Synthetic zeolites are widely used as catalysts/carriers for many petrochemical reactions and in refining processes. These materials are usually synthesized in a powder form and must be shaped prior to use in industrial reactors. This review presents the state-of-the-art of the zeolite shaping technology describing the main modifications induced by the interactions between the zeolite and the binder. Additionally, a strategy is presented to overcome the diffusion limitations associated to the microporous structure of zeolites, consisting in the introduction of hierarchical porosity in the binder. Several developments in the field of hierarchical aluminas are summarized in this article, highlighting the possibility to design different ordered/disordered mesoporous and macroporous structures.
Zeolites have been recognized as one type of the most promising adsorbents for capturing volatile organic compounds (VOCs, e.g., toluene), but their performance suffers severely from water vapor under wet conditions. In this contribution, we demonstrated that the hydrophobicity of microporous zeolites can be significantly improved by coating vertically aligned LDH nanoplatelets when the contact angle is increased from 16.5−20.1°to 44.4−64.2°. The toluene adsorption capacity of such synthesized zeolite@ LDH core@shell composites in wet conditions can thus be largely enhanced when the breakthrough time is increased from 6.4−10.8 to 20.1−27.5 min.
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