Effects of mesopore size on ethyl acetate adsorption–desorption behaviors over hierarchical ZSM-5/MCM-41 molecular sieves

Abstract

A series of micro-mesoporous structure ZSM-5/MCM-41 composites with different mesopore sizes were successfully fabricated through surfactant-mediated recrystallization method using the template agents with different alkyl chain length. Mesopore pore sizes were tuned from 2.11 nm to 5.09 nm. Taking ethyl acetate as the VOC probe molecule, the adsorption and desorption properties were evaluated by the dynamic adsorption breakthrough curves and TPD experiments. Results showed that the adsorption capacity was enhanced under dry and humid condition owing to the introduction of mesopore size structure. Especially for ZSM-5/MCM-41 (C12), its adsorption capacity reached up to 208.92 mg·g−1 and 82.29 mg·g−1 at dry and saturated humidity (4 v/v% H2O). Simultaneously, the hierarchical molecular sieves exhibited an excellent regeneration performance. Even after the fifth cycle, above 86% adsorption capacity remained under humid condition. Moreover, the adsorption kinetics of ethyl acetate on ZSM-5/MCM-41 composites followed the Bangham model. The results indicated that hierarchical composite molecular sieve can be considered as a potential adsorbent for VOCs removal.