Experimental, isotherm, kinetic, and thermodynamic studies of the novel modified zeolite ZSM-5 adsorbent for use in clean fuel processing

Abstract

Reducing the amount of sulfur in fuels is the simplest way to reduce the emission of sulfur oxide gases into the air. Among various desulfurization methods, adsorptive desulfurization stands out for its mild conditions and affordability. This research used ZSM-5 zeolite as a desulfurization adsorbent. However, adsorption capacity and selectivity are two major challenges that adsorptive desulfurization is facing. Introducing mesoporosity into zeolite is a potential solution. The study focused on mesoporous formation via desilication and dealumination. Desilication involved treating zeolite with 0.2 M and 0.5 M NaOH, while dealumination used 1 M HCl at 80 °C. Adsorbent properties were analyzed using XRD, BET, FT-IR, and FE-SEM. Initial findings indicated dealumination removed only extra-framework aluminum. Conversely, desilication removed silicon, producing a hierarchical structure even at reduced concentrations. Des-0.5M also exhibited the highest adsorption capacity for thiophene compared to the Parent sample, increasing from 4.5 to 11 mgS/g. Moreover, the adsorption capacity for larger sulfur molecules such as dibenzothiophene increased from 2.5 to approximately 6 mgS/g, indicating the significance of the hierarchical structure developed in the adsorbents. In summary, this study highlights the potential of mesoporous formation through desilication to enhance the adsorption capacity of ZSM-5 zeolite for the adsorptive desulfurization of fuels.