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1、安徽大学 硕士学位论文 微-介孔多级孔道金属-有机骨架材料的制备、储氢与催化性质 研究 姓名：徐涛 申请学位级别：硕士 专业：物理化学 指导教师：裘灵光 2010-04 摘 要 I 摘 要摘 要 多孔金属-有机骨架是指通过金属离子与多官能团有机配体配位而形成的晶 化材料。金属-有机骨架由于具有纳米尺寸的空间以及在气体存储、吸附分离、 异相催化、分子传感、磁性材料上的潜在应用，而受到广泛的关注。相比于传统 的多孔碳和无机沸石材料，多孔金属-有机骨架合成条件温和、易于修饰、弹性 的孔穴环境、结构多样性以及丰富的空间构型。然而，到目前为止多孔金属-有 机骨架一直限制在微孔范围，其较小的孔道不利于物质
2、扩散和传输，从而限制其 实际应用。开发一种稳定、易重复的方法应用于构筑孔性质可调的介孔金属-有 机骨架材料一直面临着巨大的挑战。 本论文我们提出一种简单、普适的合成策略，成功地利用超分子模板法，首 次设计和合成出具有孔径、孔体积、比表面积可调的微-介孔多级孔道金属-有机 骨架材料。本论文主要研究内容如下： 1. 以十六烷基三甲基溴化铵（CTAB）作为超分子模板合成出孔性质可调的 介孔结构金属-有机骨架。 通过铜离子和 1,3,5-苯三甲酸阴离子在表面活性剂胶束 的作用下，形成了微孔和介孔相互贯穿的 A 系列多级孔道金属-有机骨架 Cu3(BTC)2(H2O)3n (HKUST-1)。通过改变合
3、成条件，方便地合成出介孔孔径范 围在 3.8-31 nm 之间的微-介孔结构金属-有机骨架。 微-介孔金属-有机骨架的介孔 孔壁是由晶化的三维微孔骨架构成，微孔孔径为 0.82 nm。 2. 三嵌段共聚物 P123，F127 被选择作为超分子模板用以设计和构筑微-介 孔多级孔道金属-有机骨架。虽然三嵌段共聚物作为结构导向剂合成出介孔结构 的Cu3(BTC)2(H2O)3n， 但是无法实现介孔孔径的调控， 产物介孔孔径位于3.9 nm。 然而，选择 1,3,5-三甲苯（TMB）作为助孔剂以及改变 P123/TMB 的摩尔比，合 成出介孔孔径可调的微-介孔结构金属-有机骨架，介孔孔径范围为 3.9
4、-44 nm。 3. 考察了微-介孔多级孔道金属-有机骨架的低压储氢和催化性质。 低压储氢 结果显示储氢质量分数随着 BET 比表面积的增加而增加。相反，孔径越大的介 孔结构金属-有机骨架具有低的储氢性能。以双氧水氧化苯甲醇至苯甲醛为反应 模型，考察微-介孔多级孔道金属-有机骨架的催化性质。微-介孔多级孔道金属- 有机骨架具有优异的催化性质， 动力学结果显示表观数率常数 kobsd随着介孔孔径 增加至 4.9 nm， kobsd由 0.0388 降至 0.0305 min-1。 当介孔孔径从 4.9 nm 增长到 14.9 微-介孔多级孔道金属-有机骨架材料的制备、储氢与催化性质研究 II n
5、m 时，kobsd快速的增加至 0.619 min-1，表明大的介孔孔径有利于改善底物和产 物在孔道内的扩散。然而，进一步的增加介孔孔径，多级孔道金属-有机骨架的 比表面积降低，导致反应速率的降低。催化结果表明设计和合成微-介孔金属-有 机骨架来可以有效地改善多孔金属-有机骨架扩散限制效应。 关键词：关键词：多级孔道材料；金属-有机骨架；超分子模板；储氢；催化 Abstract III Abstract Porous metal-organic frameworks (MOFs) are crystalline materials with pores and channels self-as
6、sembled by the bonding of metal ions with multifunctional organic ligands. They have attracted extensive attention recently due to interest in the creation of nano-sized spaces and their potential applications in gas storage, adsorption and separation, heterogeneous catalysis, molecular sensing, as
7、well as magnetic materials. Compared with traditional porous carbons and inorganic zeolites, porous MOFs are synthesized under mild conditions and hold great promise for their ease of processability, flexibility, structural diversity, and geometrical control. However, to date porous MOFs are still l
8、argely restricted to the microporous regime despite negative impact of their small pore size on diffusion and mass transfer for their practical applications. As a result, to date reliable and reproducible methods to achieve robust mesoporous MOFs with tailored structures and tunable properties still
9、 remain a great challenge. In this dissertation, we explore a simple and versatile strategy that has allowed us to rationally design and synthesize for the first time hierarchically micro- and mesoporous MOFs with adjustable porosity. A novel supramolecular template strategy has been successfully ap
10、plied to design mesostructured MOFs with tunable pore size, pore volume, and specific surface area. The main contents of this dissertation are as follows: 1. Mesostructured MOFs with tailored porosity were obtained by choosing cetyltrimethyl ammonium bromide (CTAB) as supramolecular template. A seri
11、es of hierarchically porous MOFs, i.e., Cu3(BTC)2(H2O)3n (HKUST-1), with adjustable interconnecting micropores and mesopores was prepared by self-assembly of the framework-building blocks, i.e., Cu2+ and benzene-1,3,5-tricarboxylate (BTC3-, in the presence of surfactant micelles. These mesostructure
12、d MOFs possess a mesopore system with tunable diameters from 3.8 up to 31 nm depending on different synthetic variables. Particularly, mesopore walls in these solids are formed from a crystalline micrporous MOF containing a 3-D system of channels with a pore diameter of 0.82 nm, resulting in hierarc
13、hically micro- and mesoporous MOFs. 2. Triblock copolymers P123 and F127 were also chosen as supramolecular template to design and construct hierarchically micro- and mesoporous metal-organic framework. It was found that, mesopore system could not be tuned when only these 微-介孔多级孔道金属-有机骨架材料的制备、储氢与催化性
14、质研究 IV triblock copolymers were selected as structure-directing agent, though mesostructured Cu3(BTC)2(H2O)3n were also be obtained. Only mesopores with diameters around 3.9 nm could be obtained by using these supramolecular template systems. However, by selecting 1,3,5-trimethylbenzene (TMB) as a s
15、welling agent, mesopore sizes in these mesostructured MOF Cu3(BTC)2(H2O)3n could be tuned from 3.9 to 44 nm by changing P123/TMB molar ratio. 3. Hydrogen adsorption at low pressure and catalysis properties of these hierarchically micro- and mesoporous MOFs have been studied. Low-pressure hydrogen st
16、orage results reveal that H2 gravimetric storage capacity of such the mesostructured MOF increases with an increase in BET surface area. In contrast, mesostructured Cu3(BTC)2(H2O)3n with larger pore size showed lower H2 uptake, which is its low surface area. Transformation of benzyl alcohol to benzaldehyde by using H2O2 as the oxidant was selected as a model reaction to evaluate catalysis property of these mesostructured MOFs. These hierarchically micro- and mesoporous MOFs exhibit e
