【作者】 廖红光；

【导师】 罗和安； 刘平乐；

【作者基本信息】 湘潭大学 ， 化学工程与技术， 2013， 博士

【摘要】 己内酰胺是一种重要的有机化工原料。目前，工业化的己内酰胺生产工艺都经过了多步反应，其中占主导地位的环己酮-羟胺路线经历了环己烷氧化这一收率极低的过程，副产大量的硫酸铵副产物，不仅原子经济利用率低，还导致了严重的设备腐蚀和环境压力等问题。因此研究开发绿色工艺、简化工艺路线、降低能耗物耗，进而降低生产成本、提高竞争力成为现今研究己内酰胺生产的重点内容。丁二烯氢氰化和苯部分加氢法这两条生产己内酰胺的新工艺，避开了环己烷氧化的过程，极大的缩短了工艺流程、降低了能耗物耗、缓解了环境压力，符合原子经济性和节能减排的工艺要求，具有很好的研究价值和应用前景。本文对丁二烯氢氰化路线中的关键步骤己二腈部分加氢合成6-氨基己腈以及苯部分加氢路线中合成环己烯两个过程中的催化剂的制备与优化展开了系统的研究，取得了一定的突破，本工作的主要内容总结如下：一、己二腈部分加氢合成6-氨基己腈过程的研究采用初湿浸渍法制备了高镍负载量的负载型Ni-K₂O/α-Al₂O₃和Ni/α-Al₂O₃两种催化剂应用于液相己二腈部分加氢合成6-氨基己腈的反应。通过对催化剂进行表征分析和性能测试，发现：较低的催化剂还原温度和助剂氧化钾的引入都有利于提高活性组分镍的分散度和比表面积，减小镍的粒径，从而有利于提高6-氨基己腈的选择性；氧化钾还能增加催化剂表面的碱性位点，从而取代氨水或第一主族氢氧化物对副反应的抑制作用，可以有效的促进6-氨基己腈和己二胺两种伯胺从催化剂表面及时脱附而提高其总选择性。当钾和镍的摩尔比为0.33%，催化剂还原温度为523K，以乙醇为溶剂，在423K和2MPa H₂的无氨体系中，Ni-K₂O/α-Al₂O₃催化剂催化己二腈转化74.1%时，6-氨基己腈的选择性为84.0%，6-氨基己腈和己二胺的总选择性可达99.7%；Ni-K₂O/α-Al₂O₃催化剂的稳定性和重复利用率较高。二、苯部分加氢合成环己烯过程的研究（1）采用沉淀法，分别以ZrO₂、TiO₂、ZnO、Al₂O₃、SiO₂、介孔分子筛MCM-41和SBA-15、CNT等作载体，以Fe、Zn、La作助剂，制备了多种负载型Ru基催化剂应用于液相苯部分加氢反应中。研究发现环己烯的选择性与载体的亲水性和孔道结构特征密切相关。载体ZrO₂的强亲水性和介孔分子筛MCM-41有序的介孔结构及丰富的孔体积都能促使生成的环己烯及时从催化剂表面脱附出来，从而达到提高环己烯选择性的目的。助剂金属Fe、Zn、La等有利于提高Ru活性组分的分散度和亲水性、覆盖部分Ru活性位点，也可以进一步提高环己烯的选择性。（2）以廉价的ZrOCl₂·8H₂O作锆源，以CTAB作模板剂，采用水热合成法制备出具有类似MCM-41介孔结构的介孔氧化锆。介孔氧化锆负载Ru-Zn催化剂相对普通氧化锆负载Ru-Zn催化剂具有更好的催化苯部分加氢性能。其主要原因可能是介孔氧化锆有序的介孔结构有利于环己烯的脱附而提高了环己烯的选择性。（3）采用水热合成法、沉淀法和原位合成法，在两亲性的介孔分子筛MCM-41中掺杂亲水性的金属氧化物ZrO₂、TiO₂、ZnO等，制备了亲水性的MOx-MCM-41载体（M代表不同的金属原子Zr、Ti、Zn，x代表O原子的化学计量数）；采用双溶剂浸渍法制备了负载型的Ru-N/MOx-MCM-41催化剂（N代表了不同的助剂金属La、Ce、Zn、Fe、Cu等），考察了它们在苯部分加氢反应中的催化性能。金属氧化物ZrO₂、TiO₂、ZnO都能有效提高MCM-41分子筛的亲水性，其中以水热合成法制备的ZrO₂-MCM-41-HS载体的亲水性最强，且具有较低的比表面积和较大的孔径，相应的Ru/ZrO₂-MCM-41-HS催化剂有利于促进环己烯的及时脱附和抑制环己烯的再吸附从而表现出更优的苯部分加氢性能；助剂元素La、Ce、Zn、Fe、Cu等可以有效提高Ru活性位的分散度，能进一步提高催化剂对环己烯的选择性，其中La的分散效果最佳；苯部分加氢反应过程中，反应温度、反应时间、Ru的负载量、苯/水体积比和催化剂的钝化处理等都对环己烯的选择性有较大的影响。（4）对介孔分子筛MCM-41的合成和ZrO₂-MCM-41载体的制备过程进行系统的优化研究，探索了MCM-41的孔道结构特征和ZrO₂的性质对Ru-La/ZrO₂-MCM-41-HS催化剂催化苯部分加氢性能的影响。通过对晶化温度、晶化时间、pH值、模板剂与硅源摩尔比、添加扩孔剂、Si/Al摩尔比和焙烧温度等条件的优化，合成出比表面积相对较小、孔径和孔体积较大的有序介孔分子筛MCM-41，在苯部分加氢反应中表现出较好的性能。进一步研究了晶化温度和晶化时间对ZrO₂-MCM-41载体的亲水性和表面酸性的影响，发现不同条件下合成的ZrO₂-MCM-41的亲水性、表面羟基种类和数量以及表面酸中心类型有较大的差异。在较低的晶化温度下，通过适当的延长晶化时间，可以合成出四方型氧化锆含量较多的ZrO₂-MCM-41载体，其表面羟基数量较多，亲水性较强，有利于环己烯的脱附；其表面B酸中心数目相对较少，减少了环己烯与吸附在B酸位点上的溢流氢加氢的机会；该载体的介孔结构有序，比表面积较小，孔径和孔体积较大，热稳定性较高，这些因素共同有利于提高环己烯的选择性。以性能最优的ZrO₂-MCM-41-HS做载体制备的Ru-La/ZrO₂-MCM-41-HS催化剂，在150℃、4MPaH₂、0.3M硫酸锌溶液与苯体积比为3:1、钝化处理10h、0.2g催化剂的反应条件下，苯的转化率为65.6%时，环己烯的选择性为70.4%，环己烯收率可达46.2%。更多还原

【Abstract】 ε-Caprolactam is a very important intermediate materials for nylon-6synthesis. Allcurrent commercial ε-caprolactam synthesis processes are main based on the classicaltechnologies, undergoing the cyclohexane oxidation which is a very low efficientprocess with per pass yield of4-5%without catalyst and8-10%catalyzed by cobaltcatalyst. Moreover, the traditional processes involve have several disadvantages such asmulti-step reactions, low atom efficiency, reactor corrosion, environmental pollution andlarge amounts of ammonium sulphate and wastes. To overcome the above-mentionedproblems, it is very attractive to simplify the traditional ε-caprolactam synthesisprocesses and develop the green chemistry method for ε-caprolactam production. Thenovel production routes for caprolactam based on hydrocyanation of butadiene andpartial hydrogenation of benzene avoiding the cyclohexane oxidation have theadvantages of high yield, environmental friendliness and atomic economy. Hence, weprepared and characterized a series of catalysts and their catalytic properties in the keysteps of selective hydrogenation of adiponitrile to6-aminocapronitrile and partialhydrogenation of benzene to cyclohexene were performed.Ni/α-Al₂O₃and potassium doped Ni/α-Al₂O₃catalysts with high nickel loadingwere prepared by incipient impregnation method and characterized by nitrogenadsorption-desorption, temperature programmed reduction, hydrogen chemisorption,power X-ray diffraction, transmission electron microscopy, scanning electronmicroscopy and laser particle size analytical technique. It reveals that potassium dopedNi/α-Al₂O₃has smaller nickel crystal size, higher nickel metallic surface area and betternickel dispersion. The prepared catalysts have been tested in liquid phase hydrogenationof adiponitrile in the absence of ammonia under mild condition. It has been found thatthe Ni/α-Al₂O₃catalyst doped with potassium and reduced under relatively lowertemperature is favorable to the formation of primary amines. And the Ni-K₂O/α-Al₂O₃catalyst exhibits good performance that the selectivity of6-aminocapronitrile andhexamethylenediamine is99.7%at the adiponitrile conversion of74.1%.A series Ru catalyst supported on ZrO₂, TiO₂, ZnO, Al₂O₃, SiO₂, CNT, MCM-41and SBA-15were prepared by precipitation method and tested in partial hydrogenationof benzene. The effects of supports’ properties and co-catalysts on cyclohexeneselectivity were discussed. It has been found that Ru/ZrO₂with superior hydrophilicity and small specific surface areas and Ru/MCM-41with regular mesoporous structure andbig pore volume exhibit better cyclohexene selectivity than others. The strongerhydrophilicity, relative smaller specific surface areas, regular mesoporous structure andbiger pore volume of the Ru catalyst are beneficial to the desorption of the formedcyclohexene, which inhibits the further hydrogenation of cyclohexene to cyclohexane.Additionally, the promoters of Zn, Fe, La are in favour of improving the catalysthydrophilicity and Ru dispersion and decreasing the Ru activity, which could furtherincrease the cyclohexene selectivity.A mesoporous ZrO₂was synthesized by hydrothermal method and characterized viaX-ray Diffraction, N₂absorption-desorption technologies. The effects of crystallizationpH, crystallization time and crystallization temperature on the structure of ZrO₂wereinvestigated. Ruthenium catalysts supported on the mesoporous ZrO₂bydeposition-precipitation method were tested in the selective hydrogenation of benzene. Ithas been demonstrated that the superior hydrophilicity and regular mesoporous ofmesoporous ZrO₂are helpful to improve the cyclohexene selectivity. The Ru-Zn catalystsupported on mesoporous ZrO₂exhibits better performance than the catalyst supportedon the general ZrO₂in partial hydrogenation of benzene.Zirconia, titania and zinc oxide modified mesoporous molecular sieve MCM-41supports were prepared by hydrothermal synthesis method, in situ synthesis method andprecipitation method. Ruthenium promoted by La, Ce, Zn, Fe and Cu catalysts supportedon modified MCM-41were prepared via two solvents impregnation method. Thecatalysts were characterized by X-ray diffraction, Transmission electron microscopy,nitrogen adsorption-desorption and water/benzene static adsorptions techniques. It hasbeen found that Ru-La supported on MCM-41modified with zirconia by hydrothermalsynthesis method （Ru-La/ZrO₂-MCM-41-HS） leads to the biggest increase of thehydrophilicity and La shows better dispersity modification to Ru.Ru-La/ZrO₂-MCM-41-HS catalyst with the highest hydrophilicity and dispersity showsthe best performance in liquid phase partial hydrogenation of benzene to cyclohexene.A further research of the effect of the pore structure and surface characteristic ofMCM-41and ZrO₂on Ru catalyst performance has been developed. It has been foundthat the synthetic conditions of crystallization temperature, crystallization time, pH,mole ratio of surfactant to silicon, the dosage of assistant agent, mole ratio of Si/Al andcalcination temperature has strong impact on the specific surface area, pore volume andpore size and distribution. And relative smaller specific surface area, larger pore size and pore volume and regular mesorporous structure of MCM-41is favorable to thedesorption of cyclohexene. Furthermore, for the ZrO₂-MCM-41-HS support, the surfaceproperty like the hydrophilicity, hydroxyl content and acid site of ZrO₂also influencesthe performance of Ru-La/ZrO₂-MCM-41-HS catalyst. It revels that the hydrophilicityof tetragonal zirconia is stronger than monoclinic zirconia and amorphous zirconiabecause of the richer surface hydroxyl content and form in tetragonal zirconia.Furthermore, only Lewis acid site exists on the surface of tetragonal zirconia, whichcould avoid the further hydrogenation of cyclohexene with the spilt-over hydrogenadsorbed on Br nsted acid site and lead to better performance ofRu-La/ZrO₂-MCM-41-HS catalyst in partial hydrogenation of benzene. Over theRu-La/ZrO₂-MCM-41catalyst, the benzene conversion is65.6%and the cyclohexeneyield is46.2%.更多还原