Abstract:
In this work, the impact of CeO
x doping on a TiO
2-SiO
2 supporter on the Ag based adsorptive desulfurization for Chinese 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 SiO
2 via a novel co-impregnation method. Following CeO
x doping, the Ag species were in the form of oxides (about 5nm) instead of metallic Ag particles (about 35nm), which is due to the large amount of coordinative unsaturated sites provided by the interaction between CeO
x and TiO
2, as well as the oxidation-reduction property of CeO
x. The Ag in the active oxide state (Ag
2O
2) 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-CeO
x/TiO
2-SiO
2 was proved to be a more efficient adsorbent compared with Ag-TiO
2-SiO
2. It was found that the desulfurization performance of Ag-TiO
2-SiO
2 exhibited an excellent improvement (22.5%) after being doped with CeO
x. In the static equilibrium tests, the equilibrium sulfur capacity of Ag-CeO
x/TiO
2-SiO
2 was up to 5.38mg/g for CN-II diesel (sulfur content 952.9mg/kg) and the sulfur content of the CN-IV diesel (sulfur content 39.0mg/kg) after desulfurization was less than 10mg/kg, which could meet the CN-V standard.