Hierarchical architectures of ZSM-5 with controllable mesoporous and their particular adsorption/desorption performance for VOCs

Abstract The spherical and hierarchical ZSM-5 zeolite was hydrothermally synthesized with the function of organofunctionalized silica and organic additive. The obtained materials were prepared with nanocrystalline stacking and also its hierarchical meso-microporous architectures were explained by the modern analysis methods including X-Ray Powder Diffraction, Scanning Electron Microscope, Transmission Electron Microscope, Fourier Transform Infrared Spectroscopy, Differential Thermogravimetric Analysis and N2 adsorption/desorption. It found that the size of nanocrystals and surface topography for ZSM-5 was influenced by both the organofunctionalized silica and the organic additive. Moreover, the abundant mesoporous volumes including intercrystalline and intracrystalline mesopores for zeolitic nanocrystals and the mesoporous pore diameter could be controlled by the degrees of silanization for silica. Moreover, the evaluation on the performance of ad/desorption and cyclic application in toluene for the ZSM-5 zeolites further revealed its high adsorption ability (the highest adsorption amounts was 57.9621 mg/g) and excellent cyclic performance because of its lower steric limitations and higher diffusion rate for the organic molecules, especially the large molecule. More importantly, the exploration of Fourier Transform Infrared Spectroscopy and Differential Thermogravimetric Analysis for the hierarchical ZSM-5 directly explained the existence of organosilane phenylaminopropyl-trimethoxysilane and organic additives in the zeolitic nanocrystals. Based on the above exploration, the crystallization mechanism of ZSM-5 was put forward, which was significant to design and synthesize the hierarchical zeolites.