Simulationof H2S Adsorption and Conversionfor Coke Oven Gas Desulfurization in a NaY Zeolite Fixed Bed Usinga Modified HSDM Approach

Abstract In the desulfurization of coke oven gas (COG) using zeolites, hydrogen sulfide (H2S) adsorption is typically accompanied by the release of carbonyl sulfide (COS), which renders conventional kinetic models inadequate for accurately describing breakthrough curves. To address this limitation, a modified mathematical model coupling H2S adsorption and conversion was developed. The model has been developed on the basis of the homogeneous surface diffusion model (HSDM), which incorporates external mass transfer and intraparticle diffusion. The effects of inlet H2S concentration (250–650 ppm), volumetric flow rate (150–250 mL·min–1), and bed height (2.0–10.5 cm) on H2S breakthrough curves in a NaY zeolite fixed bed were systematically investigated. The model predictions demonstrated excellent agreement with the experimental data. The investigation into the axial and temporal distributions of H2S revealed that the change rate of the mass transfer zone (MTZ) was highly sensitive to the initial H2S concentration. In contrast, the volumetric flow rate exerted a negligible impact on the MTZ velocity, whereas it remained unaffected by the bed height. Furthermore, a parametric sensitivity analysis was conducted to evaluate the influence of key parameters on prediction performance. The results indicated that the proposed model was significantly sensitive to the axial dispersion coefficient (DL) and the film diffusion coefficient (kf), whereas the surface diffusion coefficient (Ds) exerted a minor effect on the breakthrough curves. Moreover, the calculated Biot numbers (Bi) under all investigated conditions fell within the range of 1 to 100. Combined with the results of sensitivity analysis and Biot number analysis, it was confirmed that intraparticle diffusion and film diffusion were the dominant factors affecting the H2S adsorption process on NaY zeolite. The model provides a preliminary foundation for analyzing and scaling up gas purification systems that involve adsorption and conversion processes.