【作者】 王雪涛；

【导师】 余林；

【作者基本信息】 广东工业大学 ， 应用化学， 2007， 硕士

【摘要】 离子液体中制备纳米催化剂是一个崭新的课题。本文就离子液体（IL）中制备纳米镍（Ni）及其合金硼化镍（NiB）进行了初步探索，选择苯乙烯的催化加氢和甲苯的催化氧化来评价所制备催化剂的活性，主要考察了离子液体中制备的与常规方法制备的催化剂在形貌结构及催化活性上的不同，初步探讨了离子液体对纳米催化剂的稳定机理。催化剂的制备，采用化学还原法，分别在常规水溶液和离子液体无水乙醇溶液两种不同的反应介质中制备了不同的Ni及NiB催化剂，制备出系列Ni、NiB（常规方法制备）及Ni-IL、NiB-IL（离子液体中制备）催化剂。采用自制高压反应器和气相色谱（FID检测器）对Ni、Ni-IL及NiB、NiB-IL催化剂催化苯乙烯加氢和甲苯氧化反应进行探索。加氢结果表明：两种体系中制备的催化剂对苯乙烯加氢反应均表现出一定的活性，Ni-IL、NiB-IL催化剂的催化活性显著高于对应的Ni、NiB催化剂。催化苯乙烯加氢活性（以反应物苯乙烯的转化率和产物苯乙烷的收率为评价手段）比较如下：苯乙烯转化率：Ni：32.2％，Ni-IL：57.1％；NiB：40.8％，NiB-IL：72.6％；苯乙烷收率：Ni：42.3％，Ni-IL：66.8％；NiB：43.6％，NiB-IL：84.5％。氧化结果表明：两种体系中制备的催化剂对甲苯氧化反应有一定的活性，Ni-IL、NiB-IL催化剂的催化活性高于对应的Ni、NiB催化剂。催化甲苯氧化活性（以反应物甲苯的转化率和产物苯甲酸的收率为评价手段）比较如下：甲苯转化率：Ni-19.6％，Ni-IL：34.2％：NiB：17.4％，NiB-IL：27.4％；苯甲酸收率：Ni：22.3％，Ni-IL：37.9％；NiB：20.7％，NiB-IL：34.1％。催化活性的显著差异表明，离子液体对纳米催化剂起到了很好的稳定作用。不同离子液体（包括[bmim]·BF₄、[bmim]·PF₆、[mim]·BF₄）中制备的催化剂的催化活性也进行了初步的研究。结果表明：离子液体[bmim]·BF₄中制备的催化剂的催化活性最高，初步推测，其原因在于离子液体[bmim]·BF₄具有更好的粘滞性和配位能力，从而可以更牢固的吸附在纳米颗粒的表面形成一层保护膜，防止了纳米颗粒的团聚和氧化，提高了其催化活性。采用各种现代表征技术对催化剂进行表征。XRD和TEM表征结果表明：相比于团聚明显的Ni，Ni-IL颗粒大小分布均匀，在2θ=20°～80°范围内仅有三个衍射峰，分别对应于镍的面心立方（fcc）结构中的（111）、（200）、（220）三个晶面的衍射，此外，并无其它镍的氧化物或氢氧化物的杂质峰，这表明离子液体的存在确实有效防止了Ni纳米颗粒的氧化；对于NiB-IL，则在2θ=45°有一非晶态的标识峰，具有比NiB更大的结构无序度，更小的颗粒粒径和更均匀的分布，无团聚现象。IR、UV-Vis和TG-DSC的表征则进一步验证了纳米催化剂表面离子液体层的存在，离子液体化学吸附在催化剂的表面形成一层保护膜，有效防止了纳米颗粒的团聚和氧化；另一方面，其较高的粘度也使纳米颗粒获得了较好的分散，从而提高了催化活性。更多还原

【Abstract】 It is a novel subject to prepare nano catalysts in ionic liquids. Nano metal Ni andamorphous alloy NiB catalysts were prepared with ionic liquid as a reactionintermediate. The styrene hydrogenation and toluene oxidation were used as probereactions to evaluate the catalytic activity. Some basic studies about the greatdifferences in the appearance and structure between the two kinds of catalysts, and themechanism of stabilize the nano particles were executed in the thesis.One kind of catalyst was prepared by chemical reduction method in the aqueoussolution, named Ni, NiB; the other kind of catalyst was prepared in the solution of ionicliquid and anhydrous alcohol, named Ni-IL, NiB-IL.The studies on the reaction of styrene hydrogenation and toluene oxidation wereexecuted in the self-made high pressure reactor and Gas Chromatography equipped witha FID detector. The results of hydrogenation revealed that the prepared two kinds ofcatalysts all have the catalytic activity, while the catalysts prepared in ionic liquids havea significantly higher catalytic activity compared with that prepared in conventional way.The catalytic activities were compared as follows （use the styrene conversion andphenylethane yield to evaluate the activity） : the conversion of styrene: Ni: 32.2%,Ni-IL: 57.1%; NiB: 40.8%, NiB-IL: 72.6%; the yield of phenylethane: Ni: 42.3%,Ni-IL: 66.8%; NiB: 43.6%, NiB-IL: 84.5%. The catalytic activities of oxidation werecompared as follows （use the toluene conversion and benzoate yield to evaluate theactivity）: the conversion of toluene: Ni: 19.6%, Ni-IL: 31.8%; NiB: 17.4%, NiB-IL:27.4%; the yield of benzoate: Ni:22.3%, Ni-IL: 37.9%; NiB: 20.7%, NiB-IL: 34.1%.The great differences of catalytic activity between the two kinds of catalysts indicatedthat the ionic liquids might play a key role to stabilize the nano catalysts and prevent theaggregation of active nano particles. Some basic studies of the different stable abilitiesin the different kinds of ionic liquids （including [bmim] BF₄、[bmim] PF₆、[mim] BF₄）were also executed in this work. The results revealed that the catalyst prepared in[bmim] BF₄ has the greatest catalytic activity. The reason was may be the ionic liquid[bmim] BF₄ has a bigger viscosity and stronger ability of coordination.The catalysts were characterized by XRD, TEM, FT-IR, UV-Vis and TG-DSC. The results of XRD and TEM revealed: compared with the aggregate Ni catalyst,theNi-IL has a better distribution and appearance,only three diffraction peaks wereobserved in the range of 2θ=20°～80°,which corresponding to the diffractions ofthree crystal planes （111）,（200）,（220） belongs to the face centered cubic structure.While for the NiB-IL,no sharp crystal peak was observed except the characteristic peakof amorphous around 2θ=45°,which has a wider structure disorder,a betterdistribution and appearance compared with the NiB catalyst. The results of FT-IR,UV-Vis and TG-DSC further indicated the existance of ionic liquid layer around thenano catalysts’ surface. On one hand,the ionic liquid absorbed catalysts existed in aform of protective layer to prevent the nano particles aggregation. On the other hand,the high viscosity ionic liquid worked as a good medium made the nano particles have auniform dispersion.更多还原