苯和1-辛烯对Ce(IV)Y分子筛选择性吸附脱硫的影响

选取苯和1-辛烯作为模拟汽油中的芳烃和烯烃, 分别研究它们对Ce(IV)Y分子筛选择性吸附脱硫的影响. 结果表明, 吸附剂的选择性吸附脱硫性能随着模拟油中苯和1-辛烯含量的增加而显著降低. 借助傅立叶变换红外光谱(FT-IR)、紫外漫反射光谱(UV-DRS)技术研究发现, Ce(IV)Y分子筛对苯和1-辛烯的吸附模式及影响脱硫的机理是不同的. Ce(IV)Y分子筛阳离子和苯形成π络合作用, 作用力较弱, 容易脱附; 而与1-辛烯的双键发生σ-π络合, 不容易脱附. 在Ce(IV)Y分子筛选择性吸附含苯模拟油中的硫化物时, 由于苯的存在, 苯和噻吩在分子筛表面存在严重竞争吸附, 影响了吸附剂的选择性脱硫. 而在含1-辛烯的模拟油中, 由于1-辛烯直接和分子筛发生强相互作用, 占据了吸附剂的活性位, 导致Ce(IV)Y分子筛的脱硫性能显著降低.

Effects of Benzene and 1-Octene on Desulfurization by Selective Adsorption with Ce(IV)Y

Selective adsorptive desulfurization of model gasolines containing different amounts of aromatics and olefin compounds, such as benzene and 1-octene, on Ce(IV)Y zeolite was studied using a fixed-bed adsorption column, Fourier transform-infrared spectroscopy (FT-IR), and ultraviolet diffuse reflection spectroscopy (UV-DRS) techniques. It was found that both benzene and 1-octene had strong inhibiting effects on the desulfurization which could be detected by the decreases in the desulfurization capacities of the Ce(IV)Yin the presence of benzene and 1-octene in the model gasoline. The FT-IR and UV-DRS spectra of the Ce(IV)Y zeolites adsorbing the model gasolines revealed that benzene was desorbed easily because of the formation of π-complexes, while 1-octene was desorbed difficultly due to the strong interactions between the double-bond of 1-octene and the Ce4+ to form the π-complexes through the σ-π electron donations. Therefore, it could be concluded that the effect of benzene on the adsorptive removal of sulfur compounds could be ascribed to the competitive adsorption on the Ce(IV)Ybetween the aromatics and the organosulfur compounds in the fuels. While for the effect of 1-octene, the Ce(IV)Y zeolites adsorbed preferentially the 1-octene molecules onto adsorption sites, resulting in descending adsorptive selectivity for removing thiophene from the model fuel containing even minor amount of olefin.