CeOx 掺杂TiO2-SiO2载体对Ag基柴油脱硫吸附剂性能的影响

摘要

以钛酸丁酯的乙醇溶液为钛源,硝酸铈的水溶液为沉淀剂,采用共浸渍法制备CeOx/TiO2-SiO2复合氧化物作为Ag基柴油脱硫吸附剂的载体,探究CeOx 掺杂TiO2-SiO2载体对吸附剂结构及脱硫性能的影响。结果表明,采用共浸渍法制备的CeOx/TiO2-SiO2载体中,Ce物种和Ti物种均处于充分分散的状态,掺杂CeOx 可促进Ag活性物种的分散,还会促进金属态Ag活性物种的氧化,形成高度分散的Ag氧化物(Ag2O2)活性中心,从而提高吸附剂的脱硫性能(22.5%)。在静态吸附实验中,Ag-CeOx/TiO2-SiO2对中国国II柴油(硫含量952.9 mg/kg)的吸附硫容可达5.38 mg/g,在剂油比为1：10时可将中国国IV柴油(硫含量39.0 mg/kg)中的硫含量降至10 mg/kg以下,达到中国国V柴油的标准。%In this work, the impact of CeOx doping on a TiO2-SiO2 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 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 ( Ag2 O2 ) 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.