【作者】 李杨；

【导师】 徐学诚；

【作者基本信息】 华东师范大学 ， 材料物理与化学， 2019， 硕士

【摘要】 金属纳米催化剂在催化领域占据着重要的地位,至今关于金属纳米催化剂的研究仍然是重要的研究课题。随着技术的发展,金属纳米催化剂的制备方法也有了很大的发展。其中化学合成法因具有制备工艺简单、条件相对温和、合成的金属纳米颗粒粒径均匀以及催化活性高等诸多优点,而被广泛使用。目前,前人已使用化学合成法制备了一系列金属纳米催化剂,这些催化剂大多数是选用金属氧化物或非金属化合物作为基底,在基底上合成金属纳米颗粒,再经过一系列处理最终形成的复合型催化剂。前人研究发现复合型催化剂的高效催化源于金属纳米颗粒的电子特性,而复合型催化剂基底的电子特性会对负载于其上的金属纳米颗粒产生较大的影响。因此,本论文选用富电子的树脂高分子为基底,使用化学合成法制备了金纳米树脂高分子复合材料（Au@D201）和铜纳米树脂高分子复合材料（Cu@732）,并对它们的合成方法、形成机理及各种性能进行了探究。该论文的主要内容包括以下三部分:1,Au@D201的制备及表征结果以大孔型阴离子交换树脂D201（D201）为基底通过静态吸附还原法制备了Au@D201。通过透射电子显微镜（TEM）和扫描电子显微镜（SEM）表征发现该材料中金纳米颗粒粒径均匀且极小（仅为7 nm）。对比金纳米颗粒负载前后D201树脂压汞测试所得的孔容、孔径和比表面积等参数,发现负载金纳米颗粒后D201树脂的比表面积增加,孔容从94.9 cc/g降到了17.6 cc/g。结合TEM和SEM表征结果,发现金纳米颗粒均匀分散在树脂的表面及孔洞中（大部分金纳米颗粒分布于孔洞中）。对比Au@D201和D201树脂的X射线衍射（XRD）表征结果,发现D201树脂在负载金纳米颗粒后,其特征峰的强度随着金纳米颗粒负载量的增加而降低。在30 ^o处出现了一个新的峰,峰强随着金纳米颗粒负载量增加而增强。我们认为这是由于树脂中负载的金纳米颗粒起到了交联点的作用,改变了树脂的有序度,因此形成了新的峰。X射线光电子能谱（XPS）测试发现金元素是以单质状态存在,但是金的特征峰发生了0.57 eV的偏移,表明基底材料与金纳米颗粒之间存在较强的相互作用。我们认为这种相互作用是树脂骨架中苯环上电子与金纳米颗粒之间的共轭相互作用。它起到了固定金纳米颗粒和增强金纳米颗粒分散性的作用。也正是这种共轭相互作用使金纳米颗粒成为了树脂新的交联点,使树脂的有序度发生了改变。2,Au@D201的催化性能研究我们通过调节金纳米颗粒的负载量制备出了金纳米颗粒负载量为0.1%、0.3%、0.5%、0.7%、1%和2%的一系列金纳米树脂高分子复合材料（X%Au@D201）。并将它们应用于对硝基苯酚（4-NP）还原反应检验其催化性能,研究不同金纳米颗粒负载量对X%Au@D201催化性能的影响。结果显示金纳米颗粒负载量为0.1%、0.3%、0.5%、0.7%、1%和2%的复合材料,其比催化效率分别为4.8 s^-1g^-1、8.6 s^-1g^-1、14.8 s^-1g^-1、18.2 s^-1g^-1、27.8 s^-1g^-1和36.5 s^-1g^-1。既使是金负载量仅为0.1%的0.1%Au@D201也具有优异的催化性能。对X%Au@D201的高效催化机理进行探究发现,树脂基底与金纳米颗粒之间的相互作用和金纳米颗粒的小粒径是高效催化的重要原因。3,Cu@732的制备与其催化性能研究在Au@D201的研究基础上,本文进一步选用六种不同类型树脂作为实验材料,对比分析各种树脂对Cu²⁺的吸附能力及对铜纳米颗粒的负载能力,筛选出了吸附性及负载能力最强的阳离子交换树脂732（732）作为载体,制备了Cu@732。并通过调控搅拌转速、吸附温度和溶液pH等条件,研究不同吸附条件对732树脂吸附Cu²⁺能力的影响。发现在搅拌速率为200 r/min、吸附温度为30℃且溶液pH=6时,732树脂对铜离子的吸附性能最佳。使用TEM、SEM和XRD表征了Cu@732的形貌特征,发现Cu@732中铜纳米颗粒分散性良好且粒径均匀,粒径约10 nm。应用4-NP的还原反应探究Cu@732催化性能,发现其具有优异的催化性能。更多还原

【Abstract】 Nano-metal catalysts play an important role in the field of catalysis.Research on nano-metal catalysts is still an important research topic.With the development of technology,the preparation method of nano metal catalysts has also been greatly developed.Among them,the chemical synthesis method is widely used because of its simple preparation process,relatively mild conditions,uniform particle size of synthesized nano metal particles,and high catalytic activity.A series of nano-metal catalysts have been prepared by chemical synthesis.Most of these catalysts use metal oxides or non-metal compounds as bases to synthesize nano-metal particles on the substrate,and then a series of treatments to form a composite catalyst.Previous studies have found that the high-efficiency catalysis of nano-metal catalysts originates from the electronic properties of nano-metal particles,and the electronic properties of the composite catalyst substrate have a greater impact on the nano-metal particles supported thereon.Therefore,in this thesis,nano-gold resin composites（Au@D201）and nano-copper resin composites（Cu@732）were prepared by using electron-rich resin as the substrate,and their synthesis methods,formation mechanism and various properties were studied.The main content of the paper includes the following three parts:1,Au@D201 preparation and characterization resultsAu@D201 was prepared by static adsorption reduction method using macroporous anion exchange resin D201（D201）as the substrate.The size of the gold nanoparticles in the material was uniform and very small（only 7 nm）by transmission electron microscopy（TEM）and scanning electron microscopy（SEM）.Comparing the pore volume and specific surface area of D201 resin mercury intrusion before and after loading of gold nanoparticles,it was found that the specific surface area of D201resin increased after loading gold nanoparticles,and the pore volume decreased from94.9 cc/g to 17.6 cc/g.Combined with TEM and SEM characterization results,it was found that the gold nanoparticles were uniformly dispersed on the surface of the resin and in the pores（Most of the gold nanoparticles were distributed in the pores）.Comparing the X-ray diffraction（XRD）characterization results of Au@D201 and D201 resin,it was found that the intensity of the characteristic peak of D201 resin decreased with the increase of gold nanoparticle loading after loading gold nanoparticles.A new peak appeared at 30 ^o,and the peak intensity increased as the gold loading increased.We believe this is because the gold nanoparticles supported in the resin act as cross-linking points,changing the order of the resin,thus forming a new peak.X-ray photoelectron spectroscopy（XPS）tests found that gold is present in elemental state,but the characteristic peak of gold has a displacement of 0.57 eV,indicating a strong interaction between the substrate material and the gold nanoparticles.We believe that this interaction is a conjugate interaction between electrons on the benzene ring and gold nanoparticles in the resin backbone.It acts to immobilize gold nanoparticles and enhance the dispersion of gold nanoparticles.It is also this conjugate interaction that makes gold nanoparticles a new crosslinking point for the resin,which changes the order of the resin.2,Catalytic performance study of Au@D201We prepared a series of gold nano-resin polymer composites with gold nanoparticles loading of 0.1%,0.3%,0.5%,0.7%,1%and 2%by adjusting the loading of gold nanoparticles（X%Au@D201）.They were applied to the p-nitrophenol（4-NP）reduction reaction to test their catalytic properties,and the effects of different gold nanoparticle loadings on the catalytic performance of X%Au@D201 were investigated.The results show that the composites with gold nanoparticles loading of 0.1%,0.3%,0.5%,0.7%,1%and 2%have corresponding specific catalytic efficiencies of 4.8 s^-1g^-1 and 8.6 s^-1g^-1,14.8 s^-1g^-1,18.2 s^-1g^-1,27.8s^-1g^-1 and 36.5 s^-1g^-1,respectively.Even X%Au@D201,which has a gold loading of only 0.1%,has excellent catalytic performance.The high-efficiency catalytic mechanism of X%Au@D201 was found to be an important reason for the high-efficiency catalysis of the electronic interaction between the resin substrate and the gold nanoparticles and the small particle size of the gold nanoparticles.3,Preparation of Cu@732 and its catalytic propertiesBased on the research of Au@D201,this paper further selects six different types of resins as experimental materials,compares and analyzes the adsorption capacity of various resins on Cu²⁺and the loading capacity of copper nanoparticles,and screens out the strongest adsorption and load capacity.The cation exchange resin 732（732）was used as a carrier to prepare Cu@732.The effects of different adsorption conditions on the adsorption capacity of 732 resin on Cu²⁺were studied by adjusting the stirring speed,adsorption temperature and pH of the solution.It was found that732 resin had the best adsorption performance for copper ions when the stirring rate was 200 r/min,the adsorption temperature was 30℃and the solution pH was 6.The morphology of Cu@732 was characterized by TEM,SEM and XRD.It was found that the copper nanoparticles in Cu@732 have good dispersibility and uniform particle size,and the particle size is about 10 nm.The catalytic performance of Cu@732 was investigated by the reduction reaction of p-nitrophenol,and it was found to have excellent catalytic performance.更多还原