【作者】 朴大文；

【导师】 王安杰；

【作者基本信息】 大连理工大学 ， 工业催化， 2012， 硕士

【摘要】 随着原油重质化和劣质化程度日益加深以及环保法相关规定日趋严格,人们逐渐把研究的重点放在开发新型高效的加氢精致催化剂上。过渡金属磷化物催化剂以其优异的加氢脱硫活性及稳定性越来越受到人们的关注。程序升温还原方法是目前为止比较有效可行的方法,但这种方法尚存在明显的不足,例如还原温度高、时间长、氢气消耗大及存在大量的磷损失。低温H2等离子技术的引入很好的解决了这些不足,可以更加方便快捷的合成体相过渡金属磷化物。体相过渡金属磷化物的催化活性往往较低,而负载型过渡金属磷化物具有较高的催化活性,如何选择适宜载体及简便高效的负载方法以提高催化剂的活性是目前研究的重点。本文以常见的MCM-41为载体,采用低温H2等离子体发生装置对不同负载方法制备的前体进行还原,制备负载型过渡金属磷化物(Ni2P/MCM和CoP/MCM),通过XRD及ICP对制备材料的晶相及元素组成进行了表征,并通过固定床反应考察制备好的催化剂的加氢脱硫性能。结果表明：采用共浸渍法制备负载型过渡金属磷化物时,仍需要过量磷的加入,这是由于磷与载体存在一定的相互作用；采用分步浸渍法可以避免磷与载体之间的相互作用,按化学计量比合成负载型过渡金属磷化物。对比固定床反应发现,分步浸渍法制备的负载型过渡金属磷化物的HDS活性要高于共浸渍法制备的催化剂,这是由于共浸渍法制备的催化剂中过量的P对反应存在抑制作用。通过共沉淀和等离子体法制备得到了体相CoP。在340℃C和4MPa的条件下分别考察了有无哌啶存在的环境下体相CoP对二苯并噻吩(DBT)及其加氢中间体四氢二苯并噻吩(TH-DBT)和六氢二苯并噻吩(HH-DBT)的加氢脱硫进行了研究。体相CoP同时表现出了相对较强的加氢/脱氢活性以及脱硫活性,哌啶对二苯并噻吩的加氢的抑制程度要比对其脱硫的抑制程度大。而在TH-DBT和HH-DBT的加氢脱硫过程中检测到少量的DBT及联苯(BP),这是由于在CoP催化剂上TH-DBT可以脱氢生成DBT。我们拟定了一个DBT在CoP上加氢脱硫的反映网络图。更多还原

【Abstract】 With continuous declining in quality of petroleum feedstocks and the stringent environmental legislation, people pay more and more attentions to develop novel catalysts for hydroprosessing. Transition metal phosphides have recently been the focus of research due to their high activity and stability. The temperature programmed reduction can be used to prepare the transition metal phosphides. Nevertheless, there are some obvious deficiencies. For example, the reaction has to reach a very high temperature, a big H2flow velocity and excess phosphorous is needed. The hydrogen plasma was used to sovle this problem and substitute the temperature programmed reduction.Bulk transition metal phosphides show a low HDS activities but supported transition-metal phosphides show a relatively high HDS actibities. So how to prepare the supported transition-metal phosphides more easily is the topices of recent researches. MCM-41were chosen for the carrier. The oxidic precursors, which were prepared in different ways, were reduced by hydrogen plasma. Two kinds of Supported transition-metal phosphides (Ni2P/MCM and CoP/MCM) were prepared in this way and then characterized by XRD and ICP. Hydrodesulfurization activities were studied at the fixed reactor. Because of the interaction during P and the carrier, we must add more P to prepare the supported transition-metal phosphides(MP/MCM-C) by co-impregnation method. Sequential-impregnation method can prevent the interaction and prepared the supported transition-metal phosphides(MP/MCM-S) stoichiometric. It was shown that the HDS activity of MP/MCM-S were higher than MP/MCM-C because of the excess P, which can affect HDS activity of supported transition-metal phosphides.A bulk CoP catalyst was prepared by co-precipitation of cobalt phosphate followed by hydrogen plasma(PR) with H2. The hydrodesulfurization(HDS) of dibenzothiophene(DBT) and its hydrogenated intermediates1,2,3,4-tetrahydro-dibenzothiophene(TH-DBT) and1,2,3,4,4a,9b-hexahydro-dibenzothiophene(HH-DBT) was studied at340℃and4MPa both in the presence and absence of piperidine(Pi). Bulk CoP exhibited a relatively high hydrogenation/dehydrogenation activity and high desulfurization activity. Pi retarded the hydrogenation of DBT to a greater extent than the desulfurization. A minor amount of dibenzothiophene(DBT) observed in the HDS of TH-DBT and HH-DBT is due to dehydrogenation of TH-DBT. We postulate a reaction network of the HDS of DBT over CoP catalysis.更多还原