CeOx doping on a TiO2-SiO2 supporter enhances Ag based adsorptive desulfurization for diesel

In this work, the impact of CeOx doping on a TiO2-SiO2 supporter on the Ag based adsorptive desulfurization for China's standard diesel was studied. The dispersion and valence states of Ce, Ti and Ag species were characterized, and the impact of Ce doping was investigated. The results indicated that Ce species and Ti species were dispersed evenly on the surface of SiO2 via a novel co-impregnation method. Following CeOx doping, the Ag species were in the form of oxides (about 5 nm) instead of metallic Ag particles (about 35 nm), which is due to the large amount of coordinative unsaturated sites provided by the interaction between CeOx and TiO2, as well as the oxidation-reduction property of CeOx. The Ag in the active oxide state (Ag2O2) and dispersed evenly on the supporter could interact with sulfur compounds more favorably, and therefore showed a good performance in the adsorptive desulfurization. In both static batch and dynamic breakthrough desulfurization tests, Ag-CeOx/TiO2-SiO2 was proved to be a more efficient adsorbent compared with Ag-TiO2-SiO2. It was found that the desulfurization performance of Ag-TiO2-SiO2 exhibited an excellent improvement (22.5%) after being doped with CeOx. In the static equilibrium tests, the equilibrium sulfur capacity of Ag-CeOx/TiO2-SiO2 was up to 5.38 mg/g for CN-II diesel (sulfur content 952.9 mg/kg) and the sulfur content of the CN-IV diesel (sulfur content 39.0 mg/kg) after desulfurization was less than 10 mg/kg, which could meet the CN-V standard.