摘要：The equilibrium and kinetics of adsorption desulphurization of model diesel fuel under different operating conditions were investigated. The homogeneous surface diffusion model (HSDM) and pore diffusion model (PDM) taking into account external resistance and intraparticle resistance were employed to represent the adsorption kinetics of 4,6‐dimethyldibenzothiophene (4,6‐DMDBT). The equilibrium isotherm analysis revealed that the equilibrium can be represented well by the Freundlich model. The proposed HSDM model and PDM model can successfully describe the adsorption of 4,6‐DMDBT for different operating conditions studied. The adsorbate was absorbed rapidly initially because the adsorption rate at the beginning was dominated only by external diffusion. The Biot numbers proved that the predominant rate‐controlling step was intraparticle diffusion. Simultaneously, the adsorption rate was mainly controlled by surface diffusion at lower initial bulk phase concentration and less adsorbent dosage, while pore diffusion played a significant role at higher initial bulk phase concentration and more adsorbent dosage. The temperature had little effect on the diffusion of 4,6‐DMDBT from diesel fuel. The estimated values of pore diffusion coefficient and surface diffusion coefficient were 1.55 × 10−12 m2/s and 5.855 × 10−14 m2/s, respectively. They were independent of adsorbent dosage, initial 4,6‐DMDBT concentration, and temperature, which can provide guidance for fixed‐bed adsorption columns design and process operation.
Illustration describing the pore diffusion and surface diffusion behaviour of 4,6‐DMDBT on Ag‐CeOx/TiO2‐SiO2 adsorbent particle and simulating the the adsorption desulphurization process using HSDM model and PDM model.
