Adsorption desulfurization performance and adsorption-diffusion study of B2O3 modified Ag-CeOx/TiO2-SiO2.

Abstract

In this work, the adsorption desulfurization performance and adsorption diffusion study of B2O3 modified Ag-CeOx/TiO2-SiO2 adsorbent were investigated. The adsorption desulfurization performance was studied by batch and fixed bed tests. The homogeneous surface diffusion model (HSDM) was employed to investigate the adsorption and diffusion behavior of 4,6-dimethyldibenzothiophene (4,6-DMDBT) in diesel. It was found that the addition of B2O3 promotes the dispersion of CeOx species and then further facilitates the dispersion and oxidation of Ag species resulting in higher adsorption desulfurization activity. Ag species are in state of Ag, Ag2O and Ag2O2, among which, Ag2O and Ag2O2 are found to be the active centers. The kinetics of adsorption desulfurization of model diesel fuel was investigated to provide guiding significance for the prediction of breakthrough curves of fixed-bed adsorption columns. The batch kinetic experiment modeled by HSDM model indicates that surface diffusion controls the main rate. The surface diffusion coefficient Ds determined by batch adsorption experiments is independent of operation conditions, which can be used to directly predict the breakthrough behavior in fixed bed adsorption. The modified HSDM model is proposed to describe the breakthrough behavior. Results indicate that the breakthrough time is affected by bed height, flowrate and influent concentration.