《功能化共价有机框架负载的超细钯纳米颗粒催化剂制备及其催化性能研究论文设计》由会员分享，可在线阅读，更多相关《功能化共价有机框架负载的超细钯纳米颗粒催化剂制备及其催化性能研究论文设计（99页珍藏版）》请在金锄头文库上搜索。
1、功能化共价有机框架负载的超细钯纳米颗粒催化剂制备及其催化性能研究中文摘要在过去的几十年中金属纳米催化剂在化工基础研究和实际应用方面都取得了重大突破，研究发现影响金属纳米催化剂性能的因素多种多样，包括粒径，形状，化学组成，金属与载体的相互作用以及金属与反应物/溶剂的相互作用等等。金属纳米颗粒（NPs）具有更窄的粒径尺寸能够提供更高密度的可用于催化的活性位点，从而使表面原子更具反应性，大幅度提高了原子效率并降低了金属催化剂的成本。同时发现金属NPs与载体之间存在的协同效应，配体效应以及应变效应等相互作用也在影响着纳米催化剂的催化性能。因此，可控合成性能优异的金属纳米催化剂意义重大。由共价键连接而成
2、具有高结晶度和孔隙度的共价有机框架材料(Covalent Organic Frameworks, COFs)在化学研究领域具有极为出色的应用前景，尤其在非均相催化领域，COFs清晰的骨架结构、规整的孔结构等特性，使其成为负载催化活性位点的理想载体。通过设计合成结构规整的COFs，精准调控金属NPs的尺寸，利用金属NPs与载体间的相互作用调整其分布情况以合成具有高活性高耐受性的负载型贵金属纳米催化剂是一项极为有意义的研究。在此背景下，本论文设计合成了几种不同的COFs负载的钯催化剂，并应用于催化不同的反应。本论文主要的研究内容如下:（1）设计使用三聚氯氰分别与对苯二胺和4,4-二氨基联苯缩合，合
3、成了两种具有不同孔径的三嗪基官能化COFs。基于三嗪基-COF孔道的限域效应以及杂原子与金属粒子间的协同作用，采用简单的合成策略来控制Pd团簇的生长，得到两种钯催化剂，其中的Pd纳米团簇尺寸约为0.8 nm。以此方法获得的催化剂在还原硝基芳烃的反应中表现出极为出色的催化活性。同时由于载体的孔径差异，具有较大孔的PdCOF-BPh催化剂对于硝基还原反应具有比PdCOF-Ph催化剂更加出色的催化效果。（2）在溶剂热条件下由1,3,5-三（对甲酰基苯基）苯和水合肼合成了高度稳定的吖嗪基连接的COF（ACOF）。二维薄片层状结构和丰富的吖嗪基使得制备的ACOF成为锚定金属NPs，制备非均相催化剂的理想
4、载体。通过简单的反向双溶剂法，将高度分散的超细Pd NPs成功固定在富氮晶体ACOF上制备出的PdACOF催化剂对Suzuki-Miyaura交叉偶联反应表现出优异的活性和稳定性。（3）选择合成具有成本效益的含三嗪基的二维COF（2D-COF），然后将2D-COF进行自模板碳化，以制备2D氮掺杂碳纳米片（NCNs），同时用高度分散的细小钯纳米颗粒（Pd NPs）对其改性，得到Pd/NCNs催化剂。所制备的NCNs和Pd/NCNs具有丰富的中孔和大孔的多孔结构造就了其较大的比表面积，能够促进反应物和产物的扩散和传质。所制得的Pd/NCNs催化剂在有机有害物质氯酚（CPs）的水相加氢脱氯（HDC）
5、中表现出出色的活性，稳定性和可回收性。同时，对于HDC产物苯酚随后的氢化为环己酮，展现出优异的活性和高选择性。本论文通过不同设计思路将COFs与贵金属Pd相结合合成了一系列钯纳米催化剂并考察了其催化性能。该系列工作拓展了COFs材料在催化方面的应用，同时也为后续负载型COFs纳米催化剂的制备及研究提供了一定研究基础。关键词：共价有机框架，金属纳米催化剂，钯催化，催化加氢，Suzuki-Miyaura交叉偶联反应 Ultrafine Palladium Nanoparticle Supported on Functionalized Covalent organic Framework and
6、Its Catalytic PerformanceAbstractPast decades, metal nanocatalysts have made major breakthroughs in basic research and practical applications in chemical industry. Research has found that there are many factors, including particle size, shape, chemical composition, metal-support interaction and meta
7、l-reactant /solvent interaction, etc., affect the performance of metal nanocatalysts. Metal nanoparticles (NPs) with narrower particle size are considered to provide more active sites for catalysis, thereby making surface atoms more reactive, greatly improving atomic efficiency and reducing the cost
8、 of metal catalysts. Simultaneously, it was found that interactions such as synergistic effects, ligand effects and strain effects between metal NPs and supports also affect the catalytic performance of nanocatalysts. Therefore, it is of great significance to controllably synthesize metal nanocataly
9、sts with excellent performance. Covalent organic frameworks (COFs) with high crystallinity and porosity connected by covalent bonds have extremely good application prospects in the field of chemical research, especially in the field of heterogeneous catalysis. The clear skeleton structure and regula
10、r pore structure make COFs as an ideal support for containing catalytically active sites. It is a meaningful study to synthesize supported precious metal nanocatalysts with high activity and high tolerance through design synthesis structured COFs, precise adjustment of the size and its distribution
11、of metal NPs based on the interaction between the metal NPs and supports.In this context, several different COFs-supported Pd catalysts were designed and synthesized and applied to catalyzed different reactions. The main research contents of this paper are as follows: (1) Two kinds of triazinyl-func
12、tionalized COFs (Triazinyl-COFs) with different pore diameters were synthesized by the condensation of cyanuric chloride with each of p-phenylenediamine and 4,4-diaminobiphenyl. Based on the confined effect of the triazinyl-COF pore channel and the synergy between heteroatoms and metal NPs, a simple
13、 synthesis strategy was used to control the growth of Pd clusters, and the size of the Pd nanoclusters was about 0.8 nm. The obtained catalysts showed excellent catalytic activity in the reaction for reducing nitroaromatics. At the same time, the PdCOF-BPh catalyst with larger pores has a better cat
14、alytic effect for the nitro reduction reaction than the PdCOF-Ph catalyst due to the difference in pore size of the support. (2) A highly stable azinyl-linked COF (ACOF) was synthesized from 1,3,5-tris (p-formylphenyl) benzene and hydrazine hydrate under solvothermal conditions. 2D-lamellar structur
15、e and abundant azine groups make the prepared ACOF an ideal support for preparing heterogeneous catalysts for anchoring metal NPs. The PdACOF catalyst prepared by successfully fixing highly dispersed ultrafine Pd NPs on nitrogen-rich crystals ACOF by a simple reverse double-solvent method showed exc
16、ellent activity and stability for the Suzuki-Miyaura cross-coupling reaction. (3) Choose to synthesize cost-effective two-dimensional COFs (2D-COFs) containing triazine groups, and then self-template carbonize the 2D-COFs to make 2D nitrogen-doped carbon nanosheets (NCNs), while using highly dispersed fine Pd NPs were modified to obtain Pd/NCNs catalysts. The prepared NCNs and Pd/NCNs have large specific surface areas and mesoporous and m
