【作者】 林凌；

【导师】 方维平；

【作者基本信息】 厦门大学 ， 物理化学， 2007， 硕士

【摘要】 目前，石油炼制企业为了提高催化剂的性能，油品加氢处理催化剂在开工前都需强制预硫化，这种预处理导致开工周期延长或者催化剂生产成本增加。针对这些问题，本文在现有同类催化剂的基础上，研制了一种不焙烧、不需强制预硫化的MoNiP／Al₂O₃加氢脱硫催化剂。具体的实施方案为：（1）在Mo-Ni-P-O浸渍液中添加极性有机物；（2）催化剂干燥后不焙烧。首先，对Mo-Ni-P-O浸渍液的制备和成分进行研究，发现了Mo-Ni-P-O浸渍液配制过程中的第二难配区域，并鉴定了两个难配区域的沉淀物，其中对应于难配区间I的沉淀物是磷酸镍，而对应于难配区间Ⅱ的沉淀物是MoO₃及其水合物如钼酸。激光拉曼表征的结果证明，本文所制的Mo-Ni-P-O浸渍液的主要成分是磷钼杂多酸及其与镍形成的盐。其次，针对添加极性有机物如柠檬酸可以大幅度提高MoNiP／Al₂O₃催化剂加氢脱硫性能并且容易自发硫化还原的现象，采用FT-IR、XPS、H₂-TPR、H₂-TPD和TG等技术对柠檬酸的作用机制进行研究，形成如下观点：在Mo-Ni-P-O溶液中，柠檬酸与金属组分生成配合物，此配合物以柠檬酸中的极性基团与Al³⁺化学作用的方式优先在γ-Al₂O₃载体表面吸附；配合物中的柠檬酸在开工过程中分解并在载体表面形成积炭，此积炭的存在有两种效应：一是削弱金属与载体间的强相互作用，使得催化剂在开工过程中容易自发硫化还原；二是抑制了金属组分在载体表面的迁移和聚结，提高了金属的分散度，从而有利于提升催化效率。H₂-TPR、XPS等表征方法显示焙烧将强化金属组分与载体间的强相互作用，由此表明了制备过程中采取只干燥不焙烧技术措施的合理性，这也是本文所制催化剂不需强制预硫化就有较高活性的原因之一。采用XRD、H₂-TPR、H₂-TPD等技术分别考察了添加柠檬酸的MoNiP／Al₂O₃催化剂中Mo、Ni和P含量的变化对催化剂性能的影响。在实验范围内，最佳含钼量为1．67×10^-3mol／gCat．；最佳Ni／（Ni+Mo）原子比0．278，即最佳镍含量为6．4×10^-4mol／gCat．，磷的适宜含量约3．2×10^-4mol／gCat．。相应的Mo-Ni-P-O浸渍液最佳浓度为：Mo：2．78mol／L，Ni：1．07 mol／L,P：0．65 mol／L。最后本文还考察不同反应工艺条件对添加柠檬酸的催化剂性能的影响，并进行表观动力研究，得到催化剂噻吩HDS转化率的表达式：其中θ，：相对温度，P_H相对压强，（?）：相对空速，τ：停留时间。与实验结果相比，此式计算的总平均相对偏差为3．97％更多还原

【Abstract】 At present, for improving the activity of hydrodesulfurization catalysts, thecatalysts should be presulfided before use in most refineries. However, the presulfidedprocess will result in increasing the environment contamination and the consumptionof energy. In this paper, an improving Mo-Ni-P catalyst with high activity forthiophene hydrodesulfurization （HDS） has been developed and used under theconditions without both calcination and presulfurization. The preparation charactersof the catalysts include （1） suitable amount of polar organic substance wasincorporated into the Mo-Ni-P-O impregnation solution, and （2） the catalyst thusprepared was not calcined after drying.The composition of Mo-Ni-P-O impregnation solution was studied emphatically.On studying the preparation conditions of Mo-Ni-P-O impregnation solutions, it wasfound that there are two un-preparable regions named as UPRⅠand UPRⅡ,and theprecipitates corresponding to UPRⅠand UPRⅡare molybdenum trioxide or its hydrate,and nickel phosphate respectively.The addition of polar organic substances, such as citric acid, to Mo-Ni-P-Oimpregnation solution was found to improve the HDS activities of the MoNiP/Al₂O₃catalysts thus prepared in a wide extent and to make the sulfurization of the catalystseasy．The action mechanism of citric acid was studied by FT-IR、XPS、H₂-TPR、H₂-TPD and TG techniques，the results are summarized as follows：citric acid andmetal component react to produce a complex，which is then adsorbed by supportowing to the affinity function between porlar group of citric acid and Al³⁺ of Al₂O₃support．The citric acid in this complex is decomposed in the start-up process，leadingto the formation of coke on the surface of the support. The coking of the catalyst hastwo functions:（1） weakening the strong metal-support interaction and therefore, madethe catalyst more easily be sulfurized and reduced spontaneously; （2） decreasing themoving and aggregation of the metal group, thus improving metal component dispersion, which has been proved to be in favor of improving the catalysis efficiency.The characterizations of H₂-TPR、H₂-TPD、XPS display that metal-supportinteraction would be enhanced by calcining, this directly gives rise to thedevelopment of the calcination-free technique in the preparation of the catalysts, andit is one of reasons that the catalyst has higher activity under the condition withoutpresulfrization.The effects of the variation of the contents of Mo、Ni、P in the MoNiP/Al₂O₃ catalyst containing citric acid on catalytic performances of the catalysts were investigated by means of H₂-TPR、H₂-TPR、H₂-TPR. The experiment results showthat the optimum Mo content is 1．67×10^-3 mol/gCat．；the optimum Ni／（Ni+Mo）is0．278，and corresponding，the optimum Ni content is 6．4×10^-4 mol／gCat．，theoptimum content of phosphorus is about 3．2×10^-4 mol／gCat．the optimumconcentrations of the active components in Mo-Ni-P-O impregnation solution areMo：2．78mol／L，Ni：1．07 mol／L，P：0．65 mol／L．At last，the effects of reaction conditions on the catalytic activities of thecatalysts were studied，a set of kinetics data obtain about the effects of the operatingon the conversion of thiophene were treated，and the conversion of thiophene can beexpressed as follows：whereθ，：P_H，（?），τstand for relative temperature，relalive pressure，relativeLHSV，:resident time，respectively．In this paper，the above equation is with the ARD 3．97％．更多还原