【作者】 李冬燕；

【导师】 陈长林； 徐南平；

【作者基本信息】 南京工业大学 ， 工业催化， 2005， 硕士

【摘要】 目前我国汽油和柴油品质较低,使用中产生的硫氧化物和氮氧化物等严重污染大气,因此迫切需要具有高效加氢脱硫（HDS）和加氢脱氮（HDN）的催化剂来满足油品深度加氢处理的要求。Ni₂P 催化剂具有良好的加氢脱硫和加氢脱氮性能,而非负载型Ni₂P 催化剂的比表面积很小（< 1m²/g）,为了提高其活性表面积,需将Ni₂P 负载在较高比表面积的载体上。TiO2对油品加氢精制催化剂来说,被称为新一代载体。研究表明,在Mo、CoMo 和NiMo 等钼基硫化物催化剂的HDS 反应中,TiO2载体表现出了优越的性能,比传统的Al₂O₃和SiO₂载体表现出了更加优良的催化性能。所以,本文以TiO₂作为载体,研究了TiO2负载过渡金属磷化镍的制备方法,及其对噻吩模型化物的加氢脱硫性能。本文通过程序升温还原方法合成了以TiO₂为载体的Ni₂P 催化剂,利用X 射线衍射（XRD）、低温N₂吸附（BET）等技术对催化剂的结构和性质进行了表征。结果表明,TiO₂负载Ni₂P 催化剂上,Ni₂P 为主要物相,过高Ni 负载量和过低P含量的催化剂表面存在少量Ni₁₂P₅相。催化剂的比表面积随Ni 和P 含量的增加而减小。催化剂的HDS 活性测定在高压连续流动固定床反应装置上进行,以噻吩-正己烷溶液的加氢脱硫为模型反应。在反应温度370 ℃,反应压力3.0 MPa,VHSV 为2 h^-1,氢油比（v/v）为450 的工艺条件下,Ni 负载量为15 wt%、起始Ni/P 摩尔比为1/2 时,Ni₂P/TiO₂ 催化剂对噻吩加氢脱硫反应具有良好的稳定性（>200 h）,接近100 %的脱硫转化率。在Ni₂P/TiO₂催化剂上,考察反应温度对噻吩加氢脱硫反应的影响表明了,反应温度高于300 ℃后均能达到几乎100 %的噻吩加氢脱硫转化率;反应压力、液时进料体积空速以及进料氢油比则对Ni₂P/TiO₂ 催化剂的噻吩加氢脱硫性能影响较小。另外,本文首次研究了Ni₂P/TiO₂催化剂在环烷烃脱氢反应中的释氢性能。利用有机液体氢化物贮氢,即环己烷-苯-氢（简称CBH）和甲基环己烷-甲苯-氢（简称MTH）的高度可逆化学反应贮氢是近二十年来开发的一项新型贮氢技术。传统的加氢脱氢催化剂易受到硫中毒而导致不可逆失活,而Ni₂P 具有优良抗硫性能。因此将其用于加氢脱氢反应可有效的避免硫的影响,更能够体现出Ni₂P催化剂的优点。已有文献报道Ni₂P/TiO₂催化剂在苯和甲苯的加氢反应中表现出更多还原

【Abstract】 The quality of gasoline and diesel fuel in our country now is low for high sulfur and nitrogen content. Demands for a cleaner environment have led to a global tightening in the allowed sulfur content in fuels and increased restrictions on the release of oxides. For this reason, there are considerable efforts being expended to develop new hydrodesulfurization （HDS） and hydrodenitrogenation （HDN） catalysts for the production of clean fuels. Nickel phosphide of chemical formula Ni₂P has recently been reported as a new class of high-activity HDS and HDN catalyst. The surface area of unsupported Ni₂P catalyst is rather low （< 1 m²/g）. In order to increase the active surface area, Ni₂P is dispersed on a high-surface support. Titania is a new class of support for hydrotreating catalysts,it has attracted attention in view of the higher HDS activity displayed by molybdenum-based sulfide supported on this oxide than on traditional Al₂O₃ and SiO₂. Therefore, the focus of this work was the preparation of TiO₂ supported Ni2P catalysts and their activities in HDS of thiophene. In this thesis, nickel phosphide was successfully prepared in dispersion form on TiO₂ support by means of temperature-programmed reduction of the corresponding phosphate. The phase purity of the catalyst was established by x-ray diffraction （XRD）, and the surface property was determined by N₂ BET specific surface area measurement. Results showed that Ni2P was the main phase on the TiO₂ supported catalysts. And there was Ni₁₂P₅ phase on the Ni₂P/TiO₂ catalysts with higher Ni loading and lower P loading. With Ni and P content increasing, specific surface areas of catalysts were decreasing. The activities of the TiO₂ supported Ni₂P catalysts were tested in a high-pressure fixed bed reactor for the HDS of thiophene using a model liquid feed at realistic conditions （30 atm, 370℃）. The reactivity studies showed that Ni₂P/TiO₂ was an active catalyst. The most active composition was found to have a initial synthesis Ni/P mole ratio close to 1/2, and the best Ni loading of this sample on TiO₂ was observed to be 15 wt%. Ni₂P/TiO₂ had substantially high thiophene HDS activity （almost 100 %） and stability （more than 200 h）. Reaction temperature had more effect on HDS. When reaction temperature was higher than 300 oC, HDS activity was close to 100 %. While, reaction pressure, liquid VHSV and H2/mixed oil ratio had less effect on HDS. In addition, Ni2P/TiO2 catalyst was studied in dehydrogenation of cyclohexane and methylcyclohexane for the first time. Hydrogen storage and release can be achieved by liquid organic hydride and hydrogen reversible reaction, i.e. hydrogenation and dehydrogenation reaction. The reversible hydrogen storage technology based on Cyclohexane-Benzene-Hydrogen system （CBH） and Methylcyclohexane-Toluene-Hydrogen system （MTH） was reported recently. The conventional catalysts for hydrogenation and dehydrogenation are sensitive to sulfur-containing compounds, which leads to their irreversible deactivation. However, Ni2P catalysts have favorable sulfur resistance capability. So, it is much significant that supported Ni2P catalysts are applied in hydrocarbons reactions to avoid sulfur poisoning. Previously, one literature has reported catalyst showed the good activity in benzene and toluene hydrogenation. Hydrogenation and dehydrogenation reaction are reversible. To explore the real possibilities of the use in dehydrogenation of Ni2P/TiO2 catalyst, it was used in cyclohexane and methylcyclohexane dehydrogenation. The activities of the TiO2 supported Ni2P catalysts were tested in a fixed bed reactor for the dehydrogenation of cyclohexane and methylcyclohexane at realistic conditions （1 atm, 300 oC）. With the increase of reaction temperature and the decrease of reaction H2 flow, dehydrogenation activity was better. The most active composition was found to have a initial synthesis Ni/P mole ratio close to 1/1, and the best Ni loading of this sample on TiO2 was observed to be 12 wt%. Ni2P/TiO2 had over 60 % dehydrogenation activity and 100 % product selectivity. In comparison with Ni2P/SiO2 and Ni/TiO2, Ni2P/TiO2 catalyst had much better activity in dehydrogenation reaction.更多还原