【作者】 程芹；

【导师】 张金利；

【作者基本信息】 天津大学 ， 生物化工， 2012， 博士

【摘要】 随着汽车工业的快速发展，汽车尾气中SOx对环境的污染越来越严重，因此各国相继立法以推进低硫含量（小于10ppm）清洁汽油的生产。选择性加氢脱硫是当前降低催化裂化汽油中硫含量的工业化方法，然而面临着如何提高深度加氢脱硫反应选择性的挑战。本文从研制新型选择性加氢脱硫催化剂的角度出发，选择了具有较高加氢脱硫活性的二氧化硅负载型磷化镍催化剂，研究了离子液体对其加氢脱硫性能的影响作用，通过离子液体的涂覆显著提高了加氢脱硫的选择性。主要研究内容包括：首先选择了三种二氧化硅载体制备相应的磷化镍型催化剂Ni₂P/M5、Ni₂P/EH5、NixPy/MCM-41，以噻吩和异戊烯为反应物，对其加氢脱硫活性和选择性进行了详细的研究，确定了最优的加氢脱硫操作条件。研究表明，当反应温度高于300oC时噻吩转化率由高到低的顺序为Ni₂P/M5>Ni₂P/EH5>NixPy/MCM-41，选择性的顺序为NixPy/MCM-41>Ni₂P/EH5>Ni₂P/M5；原料中初始硫含量为1350μg/g⁴50μg/g，初始烯烃含量为20vol.%⁴0vol.%，反应温度为340oC时，Ni₂P/M5催化剂上噻吩的转化率稳定在90%以上，选择性因子为4⁷。其次，研究了双三氟甲基硫酰胺类离子液体涂覆对Ni₂P/M5催化加氢脱硫性能的影响规律。结果表明，咪唑类的离子液体比吡啶类的离子液体更能有效的提高催化剂的加氢脱硫选择性；随着咪唑类离子液体涂覆量的增加，即离子液体与Ni₂P/M5催化剂质量比mIL/mcatal.由0.02增大至0.18，噻吩和异戊烯的转化率随之降低，离子液体达到单层涂覆时催化剂的选择性达到最优，当原料中的初始硫含量为800μg/g，反应温度分别为320oC和340oC时，催化剂的选择性因子分别为16.7和14.1；改变模拟汽油的组成，进一步研究了0.06-IL-Ni₂P/M5催化剂的加氢脱硫性能，催化剂的选择性随着模拟汽油中噻吩含量的减小而增大，同时烯烃含量对催化剂选择性影响较小。最后，研究了离子液体涂覆对催化剂表面特性的影响规律。热重分析和原位傅里叶变换红外分析表明，催化剂表面的离子液体在加氢脱硫反应过程中存在流失现象，当反应温度升温至340oC时离子液体阴离子的结构发生了变化；0.06-IL-Ni₂P/M5催化剂在320oC下反应110h后其加氢脱硫选择性为11.3，仍高于Ni₂P/M5催化剂，而且加氢脱硫反应过程中催化剂的Ni₂P微晶主体没有显著变化，据此可以推测离子液体分解后的产物或者剩余的阳离子吸附在了催化剂的表面，从而提高了催化剂加氢脱硫选择性。更多还原

【Abstract】 Owing to severe environmental pollution problems involving SOxresulted fromorganosulfur species in fuel oils, more stringent legislations have been enactedworldwide to impose the manufacture of cleaner gasoline with ultra-low （10ppm orless） sulfur content. The selective hydrodesulfurization （HDS） is nowadays industrialmethod for sulphur removal from of fluidized catalytic cracking （FCC） gasoline. Thechallenge of deep HDS is to provide catalysts with high HDS selectivity. In thisdissertation, the silica-supported nickel phosphide （Ni₂P/SiO₂） catalysts wereprepared and modified by coating with the ionic liquid （IL）, in order to explore aneffective method to increase the HDS selective of model FCC gasoline. Majorcontributions were listed as below.Firstly, three kinds of supported Ni₂P catalysts were prepared using the support ofM5, EH5and MCM-41, and their selective HDS performances were investigatedusing thiophene and isoamylene model FCC gasoline. Under the optimized operationconditions, the thiophene conversion decreases in the following order: Ni₂P/M5>Ni₂P/EH5> NixPy/MCM-41at the reaction temperatures higher than300oC, whilethe HDS selectivity follows the sequence of NixPy/MCM-41> Ni₂P/EH5> Ni₂P/M5.The selective HDS of the Ni₂P/M5catalyst was further evaluated using the modelgasoline with the initial thiophene content ranging from1350μg/g to450μg/g andthe initial olefin content ranging from40vol.%to20vol.%. The results suggest thatover Ni₂P/M5catalysts the thiophene conversion is higher than90%at340oC withthe selectivity factors of4⁷.Secondly, the IL-Ni₂P/M5catalysts were prepared by coating Ni₂P/M5with thebis[（trifluoromethyl）sulfonyl]amide based ionic liquid and their selective HDSperformances were investigated using model FCC gasoline. The imidazolium-basedionic liquid showed better enhancement of the selectivity than the pyridinium-basedionic liquid. The thiophene conversion decreases with increasing ionic liquid coatingquantity of mIL/mcatal.from0.02to0.18, while the selectivity factor presents amaximum with a full monolayer coverage by the ionic liquid, i.e.,16.7at320oC and14.1at340oC with the initial thiophene content at800μg/g. The selective HDS of the0.06-IL-Ni₂P/M5catalyst was further evaluated using the model gasoline with different compositions. The selectivity factor of IL-Ni₂P/M5increases with thedecreasing sulfur content and is less sensitive to the olefin contents in the feedstock.Finally, the surface chemistry of IL-Ni₂P/M5catalysts was investigated to explainthe logic concerning the HDS selectivity enhancement by ionic liquid. The ionicliquid film on the IL-Ni₂P/M5catalyst had a partial desorption and decompositionduring HDS reaction and the anion of ionic liquid demonstrates some structuraltransition as the reaction temperature is as high as340oC, reflected by the TG andin-situ FT-IR analyses. However, the selective factor of the0.06-IL-Ni₂P/M5catalystafter110h HDS reaction at320oC was11.3, still higher than that of the Ni₂P/M5catalyst. Meanwhile, the HDS processes had no obvious effect on the bulk ofcrystallites Ni₂P particles of IL-Ni₂P/M5catalyst. Therefore, it is reasonable to deducethat, the decomposition products of the ionic liquid and part of the cation bind tocatalysts surface, contributing to the maintenance of the selectivity enhancement witha long-term stability.更多还原