酸催化及竞争吸附对CeY分子筛吸附脱硫性能的影响（英文）

Effects on Adsorption Desulfurization of CeY Zeolites:Acid Catalysis and Competitive Adsorption

采用液相离子交换(LPIE)法制备了CeY分子筛,并研究烯烃和芳烃对其吸附脱硫性能的影响.利用固定床穿透曲线技术研究吸附剂的脱硫性能,结果表明:烯烃和芳烃的存在均导致吸附剂吸附硫容量减少,然而,烯烃的影响明显强于芳烃.采用原位傅里叶变换红外(FTIR)光谱技术研究噻吩、环己烯和苯的吸附行为,结果发现:烯烃和芳烃降低吸附剂脱硫性能的实质分别为吸附剂表面酸性导致的酸催化反应和π-络合吸附的芳烃分子与硫化物分子的竞争吸附.另外,烯烃的影响取决于吸附剂的表面酸性,尤其是强B酸(Br?nsted酸)中心.这是由于B酸中心会导致烯烃和噻吩发生质子化反应,且质子化物种易于进一步发生低聚反应.生成的低聚物覆盖吸附活性中心导致吸附剂对其它噻吩分子的吸附能力降低.

The effects of olefin and aromatic hydrocarbons, as wel as the acidic catalytic reactions on the adsorption desulfurization performance of CeY zeolites prepared by liquid phase ion exchange （LPIE） technique were systemical y investigated. The capacities of sulfur removal were measured by fixed-bed breakthrough experiments. It is shown that the desulfurization performance of the adsorbents is reduced by olefin and aromatic hydrocarbons in model gasoline with olefin having a more significant effect. In-situ Fourier transform infrared （FTIR） spectroscopy was used to study the adsorption of thiophene, cyclohexene, and benzene on the zeolites. The effects of the olefin and aromatic hydrocarbons differed. For the olefins, the desulfurization capacity of the CeY adsorbents depends on the surface acidity of the zeolites, particularly on the Br？nsted acidity. Protonation of olefin and thiophene compounds can be found at Br？nsted acidic sites. It is the oligomerization of the protonated species that decrease the adsorption of＆amp;nbsp;other thiophenes. It is, therefore, the acidic catalytic reactions caused by the strong Br？nsted acidity on the adsorbent surface that could be the dominant factor for olefin hydrocarbons. While for the aromatic hydrocarbons, the decreased desulfurization capacity can be ascribed to the competitive adsorption on the active sites byπ-complexation between the organic sulfur compounds and arenes.