【作者】 陈萍；

【导师】 李瑞丰；

【作者基本信息】 太原理工大学 ， 工业催化， 2007， 博士

【摘要】 苯加氢生成环己烷是一重要的生产过程，环己烷作为苯完全加氢的产物，不仅是一种重要的化工原料，而且还是一种优良的溶剂。但苯是一种致癌物质，严重危害了人类健康，随着人类环保与健康意识的增强，从溶剂油和燃料中除去苯及芳烃已成为油品精制工业中的一项重要内容。工业上常采用的苯催化加氢主要有气相催化法和液相催化法两种。气相法虽然催化剂与产品容易分离，反应压力低，但所需温度较高，设备庞大，且温度不宜控制，投资费用高；液相法虽然反应温度易于控制，但所需压力高，转化率较低。因而选择和制备在温和的条件下高效液相苯加氢催化剂是有效克服当前在苯加氢生产过程中的弊端、提高生产率、降低生产成本的一个重要手段。此外，对于如何在温和条件下脱出溶剂油中的微量苯的研究很少，而除去苯是生产高质量溶剂油的关键。基于此，本文在新型高效苯液相加氢催化剂的开发和研制以及除去溶剂油中苯的工业应用方面进行了下列工作：1．金属配合物／分子筛催化剂对苯加氢催化性能的研究1)采用自由配体法制备了系列MSalen／Y（M=Ni，Pd and Ru）和RuL／Y（L=phenanthroline（phen），2，2′-bipyridyl（bipy）and N，N′-ethylenebis（salicylidene-aminato）（Salen））催化剂，分别考察了金属元素性质和不同配体性质对所制催化剂催化加氢性能的影响，结果表明RuSalen／Y的催化加氢活性优于PdSalen／Y和NiSalen／Y；不同性质与结构的配体对所制催化剂的催化加氢性能也有很大的影响，以Salen希夫碱为配体所制备的RuL／Y催化活性高于以二联吡啶（bpy）和邻菲咯啉（phen）为配体所制备的催化剂。2)以Salen、Salpn（N，N′-bis（salicylidene）propane-1，3-diamine）、Salicyhexen（N，N′-bis（salicylidene）-1，2-cyclohexanediamine）三种不同希夫碱为配体，制备了系列Ru（Schiff-base）／Y催化剂，并采用XRD、ICP、N₂-adsorption、FTIR、UV-vis、DTA和催化加氢反应等手段对所制催化剂进行了详细表征。结果表明：所制催化剂中希夫碱配体改变了中心离子的电子结构，使其更容易与反应物分子形成配位过渡态，配位活化的反应物分子更易于转化为产物。与离子交换法制备的母体Ru／Y相比，所制催化剂对苯的催化加氢性能明显提高。另外，不同几何尺寸的希夫碱配体对所制催化剂的加氢催化性能也有很大影响，随其几何尺寸的增加，相应催化剂的催化活性依次降低。3)采用自由配体法将系列Ru（5，5′-X₂-salen）（X=H，Cl，Br or OCH₃）封装于Y型分子筛的孔腔中，并采用XRD、ICP、N₂-adsorption、FTIR、UV-vis、DTA和催化加氢反应等手段对所制催化剂进行了详细的表征。结果表明：不同性质的取代基对配体芳环上的氢原子取代不仅可改变封装配合物的电子和光谱性质，而且还对催化剂的加氢催化活性产生很大的影响。具有吸电子基团和给电子基团取代基的催化剂的加氢性能均低于末被取代的催化剂。所制备的催化剂在苯加氢反应中具有良好的稳定性，可被重复使用。4)以H₄Salen、H₄Salpn和H₄Salicyhexene为配体，制备了系列的Ru（H₄Schiff-base）／Y催化剂，并采用XRD、ICP、N₂-adsorption、FTIR、UV-vis、DTA和催化加氢反应等手段对所制催化剂进行了详细的表征。在苯加氢反应中Ru（H₄Schiff-base）／Y的催化活性明显高于相应的Ru（Schiff-base）／Y，其中Ru（H₄Salen）／Y的催化活性最高，表明希夫碱配体中C=N键的加氢导致中心Ru（Ⅲ）离子的配位环境有很大改变。所制备的Ru（H₄Salen）在苯加氢反应中表现出良好的稳定性，经重复使用三次后，仍保持其原有的催化活性。此外还就反应温度和氢气压力对Ru（H₄Salen）／Y催化性能的影响进行了考察。2．负载金属分子筛催化剂对模拟溶剂油及6^#溶剂油中苯液相加氢催化性能研究1)以沸石HY、HUSY、Hβ载体制备了负载金属Ru、Pt及Pd催化剂。以含0.06％苯的正己烷溶液为反应物，在反应温度313K、总压力1.0MPa条件下，考察了载体和金属类型对苯液相加氢活性的影响。结果表明，金属组分的性质、沸石载体的结构和表面酸性对负载金属催化剂的催化性能有很大影响；USY负载不同金属催化剂具有不同的加氢活性，Ru与Pt具有单位质量等同的加氢能力；在所考察的三种不同载体中，催化加氧活性按照下列顺序递减：Ru／HY＞Ru／HUSY＞Ru／Hbeta。2)以Si-MCM-41、Al-MCM-41（1）（n（Si）／n（Al）=15）和Al-MCM-41（2）（n（Si）／n（Al）=10），以及用NH₄NO₃或HAc的醇溶液分别与Si-MCM-41离子交换所得的H-MCM-41（N）和H-MCM-41（H）为载体制备了系列负载Ru催化剂。采用N₂吸附、XRD和H₂-TPR表征了负载Ru前后催化剂的结构及Ru金属在各种载体表面上的分散状态；以含0.5％（质量分数）苯的环己烷溶液为反应物，在298K、3.0MPa反应条件下，考察了催化剂的苯加氢反应性能。结果表明，载体MCM-41的n（Si）／n（Al）和表面化学组成等性质对金属Ru在其表面上的分散状态、还原性及催化性能均有影响。对苯转化率与反应时间的关系曲线进行拟合，发现其遵循一级动力学方程，加氢反应速率常数按照Ru／Al-MCM-41（2）＜Ru／Al-MCM-41（1）＜Ru／Si-MCM-41＜Ru／H-MCM-41（H）＜Ru／H-MCM-41（N）的顺序递增，Ru／Si-MCM-41的较高催化活性来自于Si-MCM-41的高比表面积和金属Ru的高分散性，由于载体酸性的增加，H-MCM-41负载催化剂的表现出较高的加氢活性。3)分别采用原位合成法和离子交换法制备了Y／MCM-41和USY／MCM-41两种复合分子筛，运用XRD、N₂吸附等手段对其结构和比表面积进行了表征，并以其为载体制备了负载金属Ru催化剂，考察了其负载的金属Ru催化剂的加氢活性。中微孔复合分子筛负载钌催化剂的液相苯加氢反应活性均高于单一载体负载的催化剂，并且反应活性同复合分子筛中两种组分所占的比例相关，其中Ru／（HUSY／MCM-41）（1：1）显示了最高的反应活性。4)以Ru／（HUSY／MCM-41）（1：1）、Ru／H-MCM-41（N）、Ru／HUSY和Ru／HUSY与不同沸石分子筛助剂机械混合组成的混合物为催化剂，考察了它们在低温下对模型反应物和6^#溶剂油的催化加氢行为。结果表明，Ru／（HUSY／MCM-41）（1：1）、Ru／H-MCM-41（N）和Ru／HUSY在6^#溶剂油液相加氢脱苯反应中具有不同的反应性能，反应活性顺序为Ru／HUSY＞Ru／（HUSY／MCM-41）（1：1）＞Ru／Si-MCM-41（N）；负载催化剂的抗硫性同载体的酸性相关，以具有高强酸性USY为载体制备的负载催化剂，具有良好的抗硫性；在Ru／HUSY中加入氢型沸石分子筛助剂（HY，HUSY，HBeta），可以大大提高催化剂的加氢活性与抗硫性，且催化剂的加氢活性和抗硫性随着氢型沸石分子筛助剂HUSY加入比例的增大先快速增大，之后保持不变；加入的钠型沸石分子筛助剂（NaUSY，NaY）也对催化剂的抗硫性有所提高。更多还原

【Abstract】 Hydrogenation of benzene to cyclohexane, an important chemicalengineering raw material and an excellent solvent, has been known to be animportant industrial process. In recent years, there is an increasing demandfor benzene reduction in petroleum product, and especially in gasoline,diesel and solvent oil because benzene, as a carcinogen, seriously harms thehealth of human beings. The most frequent benzene elimination route is bycatalytic hydrogenation. In industry, benzene hydrogenation can be carriedout in gas phase or liquid phase. Compared with gas phase hydrogenation,liquid phase hydrogenation has the advantages of lower reactiontemperature, lower investment and ease in reaction temperature control, butit requires higher hydrogen pressure and has lower conversion. So,preparation and development of efficient liquid phase benzenehydrogenation catalysts is an important means to overcome thedisadvantages in the present liquid phase benzene hydrogenation. Further, elimination of benzene in the solvent oil by hydrogenation under mildreaction conditions is also the key to the production of high-quality solventoil, but so far little work is reported in this aspect. Based on this, in thispaper, the main work was focused on preparation and development ofnovel hydrogenation catalysts and their application in elimination ofbenzene in 6^# solvent oil by hydrogenation.1. Hydrogenation of benzene over metal complexes encapsulatedin molecular sieves1) MSalen/Y（M=Ni, Pd and Ru） and RuL/Y（L=phenanthroline（phen）,2,2’-bipyridyl（bipy） and N,N’-ethylenebis（salicylidene-aminato）（Salen）were prepared by flexible ligand method and characterized by XRD,N₂-adsorption, FTIR, DRS and DTA. The catalytic results show that theproperties of metal ions and ligands have great influence on the catalytichydrogenation activity of the prepared catalysts. Among the selected threemetal ions, RuSalen/Y has much higher catalytic activity than NiSalen/Yand PdSalen/Y. RuL/Y with different ligands exhibit different catalyticperformance in benzene hydrogenation, indicating that the ligands withdifferent properties and structures can greatly change the catalytichydrogenation performance of the prepared catalysts. The catalytichydrogenation activity of Ru（Salen）/Y is much higher than that ofRu（phen）₃/Y and Ru（bipy）₃/Y.2） Three types of Schiff-bases, Salen, Salpn（N,N’-bis（salicylidene） propane-1,3-diamine） and Salicyhexen（N,N’-bis（salicylidene）-1,2-cyclohexanediamine） with different size were used as ligands forpreparation of Ru（Schiff-base）/Y. The results of XRD, N₂-adsorption,FT-IR, DRS, DTA and catalytic reaction show that Schiff-base ligands inthe prepared catalyst change the electronic state of central metal atom, thusmake the catalyst to form transition coordinative state with reactionsubstrate more easily. Compared with Ru/Y prepared by ion-exchangemethod, the catalytic activities of Ru（Schiff-base）/Y increased significantlyin benzene hydrogenation. The geometry size of different Schiff-baseligands has strong influence on the catalytic performance of the preparedcatalysts and with the increase of the ligands in the size, the activity of thecorresponding Ru（schiff-base）/Y catalyst decreases.3) Ruthenium（5,5’-X₂-Salen） complexes, where Salen=N,N’-ethenebis（salicydene-aminato） and X=H, Cl, Br or （OCH₃）, wereencapsulated in the cavities of zeolite by flexible ligand method andcharacterized by XRD, ICP, N₂-adsorption, FTIR, UV-vis, DTA andcatalytic hydrogenation reaction. It is found that substitution of thearomatic hydrogen atoms of the Salen ligand by different groups not onlycan modify the electronic and spectra properties of the encapsulatedcomplex, but also has great influence on the catalytic hydrogenationperformance of the prepared catalysts. The benzene hydrogenation catalyticactivities of the prepared encapsulated catalysts with electron-withdrawing group like -Cl, -Br or electron-donating group like -OCH₃ are lower thanthat of the un-substituted encapsulated catalyst. The prepared catalysts arestable in benzene hydrogenation and can be reused.4) A series of Ru（Ⅲ） tetrahydro-Schiff base complexes （denoted asRu（H₄Schiff base） with Schiff base=Salen, Salpn and Salicyhexen） wereencapsulated in the supercages of zeolite Y by flexible ligand method. Theprepared catalysts were characterized by XRD, UV-vis, FTIR, ICP, as wellas N₂-adsorption techniques. It is shown that upon encapsulation in zeoliteY, Ru（Ⅲ） tetrahydro-Schiff base complexes exhibited higher activity forthe liquid phase hydrogenation of benzene than the correspondingRu（Ⅲ）-Schiff base complexes. This indicates that hydrogenation of theC=N bond of the Schiff base ligands led to a modification of thecoordination environment of the central Ru（Ⅲ） cations. The stability of theprepared catalysts has also been confirmed against leaching of the complexmolecule from the zeolite cavities, as revealed by the result that no loss ofcatalytic activity was observed within three successive runs withregeneration. In addition, the reaction temperature and H₂ pressure on thehydrogenation performance of Ru（H₄Salen）/Y were also investigated.2. Hydrogenation of benzene in model reactant and 6^# solvent oilover molecular sieves supported metal catalysts1) A series of Ru, Pd and Pt catalysts supported on HY, HUSY, and Hβwere prepared, and their liquid phase catalytic hydrogenation performance was investigated for 0.06% benzene/hexane model reactant at reactiontemperature of 313K and total pressure of 1.0MPa. The results show thatsupport, metal and reaction conditions have great influence on the catalyticperformance of the prepared supported catalysts; different metals supportedon USY exhibit different hydrogenation activity, and the hydrogenationactivity for unit mass Ru is comparable with metal Pt; the hydrogenationactivity for Ru catalysts supported on different zeolites decreases in theorder of Ru/HY＞Ru/HUSY＞Ru/Hbeta. The optimum hydrogenationactivity can reach at 313K and 1.0MPa H₂ reaction condition.2) A series of Ru catalysts supported on Si-MCM-41, Al-MCM-41（1）（n（Si）/n（Al）=15）, Al-MCM-41（2）（n（Si）/n（Al）=10）, as well as H-MCM-41（N） and H-MCM-41（H） from ion-exchanged Si-MCM-41 with thesolution of NH₄NO₃ or HAc in ethanol were prepared and characterized byN₂-adsorption, XRD and H₂-TPR techniques. The liquid phasehydrogenation reaction of benzene on these catalysts was studied by amodel reactant containing 0.5% （mass fraction） benzene in cyclohexane at298K and 3.0MPa. It is indicated the dispersed state, reducibility andcatalytic activity of supported Ru depended on the n（Si）/n（Al）, surfacecomposition and acidic nature of supports. The results of the benzeneconversion as a function of reaction time show that the catalytic reactionfollow a first-order kinetic equation. The reaction rate is in order ofRu/Al-MCM-41（2）＜Ru/Al-MCM-41（1）＜Ru/Si-MCM-41＜Ru/H-MCM -41（H）＜Ru/H-MCM-41（N）. The Si-MCM-41 with very high surface areaallows for better dispersion of the Ru particles, and the Ru/Si-MCM-41shows higher activity as compared to the Ru/Al-MCM-41. The acidity ofH-MCM-41 results in the improvement of catalytic activity, which isattributed to alternative pathway induced by spillover hydrogen in themetal-acid interfacial region.3) Y/MCM-41 and USY/MCM-41 composites were prepared byin-situ synthesis method and ion-exchange method respectively and theirtextural and structural characteristics were studied by variousphysicochemical means. The two kinds of composites were used assupports for preparation of Ru supported catalyst and their catalyticperformance of the prepared catalysts in liquid benzene hydrogenationwere investigated. The catalytic results showed that Ru supported onY/MCM-41 or USY/MCM-41 composite has higher catalytic activity thanon single phase support and their activities are related to the weight ratio ofY to MCM-14 or USY to MCM-41 in the composites, in which Rusupported on USY/MC-41with a HUSY/MCM-41 weight ratio of 1exhibits the highest activity.4) The low-temperature catalytic hydrogenation for benzene in modelreactant and 6^# solvent oil over Ru（HUSY/MCM-41）（1:1）, Ru/H-MCM-41（N）, Ru/HUSY and the mechanical mixture of Ru/HUSY with differentmolecular sieve promoters were investigated. It is found that the catalytic hydrogenation rate for model reactant over various catalysts is in the orderof Ru/（HUSY/MCM-41）（1:1）＞Ru/Si-MCM-41（N）＞Ru/HUSY, whilefor 6^# solvent oil is in the order of Ru/HUSY＞Ru/（HUSY/MCM-41）（1:1）＞Ru/Si-MCM-41（N）. The different catalytic activities of variouscatalysts for two reactants are due to the presence of small quantity sulfurcompounds in the 6^# solvent oil, while various catalysts have differentsulfur resistance. The sulfur resistance of the catalysts is related to theacidity of the support and the good sulfur resistance for Ru/USY isattributed to the stronger acidity of HUSY. Both the hydrogenationbehavior and the sulfur resistance of Ru/HUSY for 6^# solvent oil, can begreatly improved by addition of H-type molecular sieves （HY, HUSY andHeBeta） promoters to it. The hydrogenation activity and sulfur resistance ofRu/HUSY increased with the increase of promoter amount and keptconstant until weight ratio of HUSY to Ru/USY reached 5. In addition, thepromoters of NaUSY and NaY could also improve the sulfur resistance ofRu/USY due to their adsorption to sulfur compounds.更多还原