H2S adsorption on NaY zeolite

Abstract

Abstract In this work, high-pressure H2S adsorption data in equilibrium and fixed bed conditions using NaY zeolite as adsorbent were determined. Adsorption and desorption isotherms for different temperatures and H2S partial pressures up to 1.2 bar were obtained experimentally and modelled with Toth and Dubinin-Astakhov equations in order to give information about adsorbate/adsorbent and adsorbate/adsorbate interactions. H2S adsorption in a fixed bed column was achieved for different inlet volumetric flow rates and breakthrough curve data were evaluated considering adsorbed amount, length of mass transfer zone, contributions of internal and external mass transfer resistances and were modelled with Linear Driving Force (LDF) model to estimate adsorbent particle's effective mass transfer coefficient. Equilibrium results indicate maximum uptake capacities are above 6.0 mol kg−1 for highest partial pressures. Isotherms' modeling suggests the predominance of physisorption of H2S in NaY zeolite. However, a hysteresis effect was observed for desorption curves and attributed to H2S chemisorption on zeolite surface, as pointed out by strongly favorable isotherms obtained. Fixed bed adsorption data showed breakthrough curves were nonsymmetrical, which indicated the presence of internal resistance mainly, probably due to the microporosity of adsorbent particle. In accordance, mass transfer zones did not vary significantly with inlet flow rate. Effective intraparticle mass transfer coefficients obtained with LDF model increases as flow rate increases, due to a higher availability of H2S molecules at adsorbent surface, which increases the driven force necessary for mass transfer in the intraparticle region.