A hierarchically porous diatomite/silicalite-1 composite for benzene adsorption/desorption fabricated via a facile pre-modification in situ synthesis route

Abstract

A novel, hierarchically porous diatomite/silicalite-1 composite with a high benzene removal efficiency was prepared via a facile coating process. Silicalite-1 nanoparticles (Sil-1nano) were synthesized in situ on the surface of the pre-modified diatomite support by using a mild, low-temperature reflux reaction method. The obtained composite possessed a hierarchically porous structure, involving micropores and stacking mesopores from the silicalite-1 nanoparticles, and it retained the macropores from the diatomite support. The specific surface area and micropore volume of the composite were 348.7m2/g and 0.127cm3/g, respectively, with a zeolite loading amount of up to 60.2%. The diatomite/silicalite-1 composite exhibited considerably higher static and dynamic benzene adsorption capacities (94.9mg/g (Sil-1nano) and 246.0mg/g (Sil-1nano) respectively) per unit mass of zeolite than did the synthesized Sil-1nano and commercial ZSM-5. Moreover, the introduced macroporosity of the diatomite reduced the mass transfer resistance of the nanoparticles because of their improved dispersity, and it provided more possible entryways for benzene molecules, leading to better penetration of benzene than for Sil-1nano or commercial ZSM-5. The composite showed steady reversibility after 4 adsorption cycles, further demonstrating the promise of such a novel synthesized adsorbent for the removal of volatile organic compounds in industrial applications.