Study of the inner surface silanization of zeolite to improve the toluene capture ability in humid environment and fixed-bed adsorption kinetics analysis

Although Y zeolites are considered as a promising adsorbent for capturing volatile organic compounds (VOCs), its hydrophilic nature causes a significantly decrease in VOCs adsorption performance due to the pervasive water vapor in VOCs streams. Herein, a facile approach is proposed to significantly enhance the hydrophobicity by grafting methyl on the inner surface of Y zeolite. Attachment of methyl to the inner surface leads to a significant reduction in water affinity, resulting in a notable enhancement of toluene adsorption capacity in humid environment. The silanization process and the evolution of silane species are further elucidated through in-situ DRIFTS, NMR and TGA. Adsorption kinetics reveals that inner surface silanization reduces the adsorption rate constant of water by 50 %. However, the outer surface silanization with propyl is ineffective in mitigating the detrimental impact of water on the toluene adsorption. Moreover, Yoon-Nelson (Y-N) model analysis is applied to predict the breakthrough characteristics of fixed-bed adsorption and to evaluate the applicability in actual industry. In this work, this regioselective silanization approach could provide a facile strategy for controlling VOCs in humid environment.