Facile and controllable preparation of nanocrystalline ZSM-5 and Ag/ZSM-5 zeolite with enhanced performance of adsorptive desulfurization from fuel

Abstract

The diffusion limitation owing to the long and narrow pore structure in traditional ZSM-5 zeolite could restrain the adsorptive desulfurization performance towards thiophene sulfur compounds from fuels. Herein, ZSM-5 zeolite nanocrystals were successfully fabricated using steam-assisted gel crystallization strategy to control the size of zeolite particles within 70 ∼ 160 nm. Compared to traditional micron ZSM-5, ZSM-5 zeolite nanocrystals could effectively reduce the diffusion pathway, enlarge the specific surface area, and increase exposure of adsorption sites, which could enhance the desulfurization performance. ZSM-5 nanocrystals with a mole ratio SiO2/Al2O3 of 200 exhibited a satisfactory desulfurization efficiency, and the breakthrough capacity attained 0.0509 mmol S/g adsorbent. After ZSM-5 nanocrystals were ion-exchanged with NH4+ and Ag+, both mesoporous characteristics and the Lewis acid (L-acid) sites were enhanced, which promoted the adsorption desulfurization performance. Furthermore, nanocrystalline ZSM-5 and Ag/ZSM-5 also exhibited acceptable regeneration performance. This study is expected to provide an effective strategy and a facile method to prepare nanocrystalline ZSM-5 based adsorbents for the development of efficient desulfurization materials.