Effects of B2O3 on the adsorption desulfurization performance of Ag-CeOx/TiO2-SiO2 adsorbent as well as its adsorption-diffusion study

Abstract

The effects of B2O3 on the adsorption desulfurization performance of Ag-CeOx/TiO2/SiO2 adsorbent as well as its adsorption-diffusion study were investigated. The results show that the optimum preparation conditions are as follows: co-impregnation, B2O3 doping at B to Ti mole ratio of 1:2, supporter calcinating at 550 ℃, active component calcinating at 450 ℃ and volume ratio of ethanol to water at 4:1, which shows good adsorption desulfurization activity due to the high dispersion of Ag and CeOx species on surface of adsorbent and providing more surface defect sites after B2O3 loading. Simultaneously, the Computational Fluid Dynamics (CFD) model was further applied to investigate the adsorption-diffusion behavior inside column to reveal the mechanism of adsorption-diffusion behavior. The results demonstrate that the adsorption desulfurization process can be well described by the porous media CFD model. The entire fixed bed remains adsorbed during the initial adsorption stage. Subsequently, the adsorption efficiency of adsorbent at the fixed bed entrance begins to decrease, and gradually reaches saturation. Finally, the entire fixed bed loses its adsorption capacity. The mass transfer rate is used to further analyze the adsorption-diffusion transfer process in fixed bed, which decreases with the progress of the adsorption process.