【作者】 罗亚莉；

【导师】 谭必恩；

【作者基本信息】 华中科技大学 ， 高分子化学与物理， 2013， 博士

【摘要】 二氧化碳(C02)的大量排放所导致的全球变暖给地球环境带来了严重的威胁。为了稳定目前大气中CO2的浓度,CO2的捕获成为国内外关注的焦点,采用有效的方法从工业烟道气中捕获CO2成为一项重要的研究课题。微孔材料因其具有低密度、大比表面积和高孔隙率而在CO2捕获方面有着潜在的应用。近几年来,微孔材料尤其是微孔有机聚合物的设计与合成取得了显著的研究成果。然而,到目前为止,绝大多数材料的合成需要精细地设计单体结构,选择合适的反应路径。此外,反应过程中通常会用到昂贵的过渡金属催化剂或有毒的溶剂。这些因素均会增加材料的生产成本,从而制约微孔聚合材料的工业化生产及其在CO2捕获方面的大规模应用。因此,低成本法合成高比表面积的微孔聚合物材料,成为材料学家和化学家当前亟待解决的重要课题之一。本论文以一些低成本的工业化原料为构筑单体,采用简单的合成方法制备了高比表面积的微孔聚合物材料。通过红外、固体核磁、氮气等温吸附-脱附等表针手段对所合成的微孔材料进行了表征,并初步研究了这些微孔有机聚合物材料在CO2吸附与分离方面的应用。论文研究的主要内容及结论如下：(1)芳香羟甲基化合物能够在Lewis酸的存在下发生Friedel-Crafts烷基化反应。通过FeCl3催化,苯甲醇和1,4-苯二甲醇自缩合反应,分别合成了两种具有高比表面积的超交联聚合物材料HCP-BA和HCP-BDM。低温氮气吸附实验结果显示,所合成的两种聚合物均具有一定的微孔结构,BET比表面积分别为742m2g-1和847m2g-1。值得一提的是,这是首次采用单官能团化合物作为自缩合单体得到高比表面积聚合物的报道。CO2吸附测试表明,273K/1.0bar下,两种材料的CO2吸附量分别为8.46wt%和12.6wt%。相对于二者的比表面积,HCP-BDM的C02吸附量显著提高的原因可归结于其较小的孔径尺寸和材料中残存的氧原子。(2)理论研究和实验结果表明：多孔骨架中氮原子的存在有利于提高材料的C02吸附性能。因此,以商业化原料三聚氰胺和二酐单体为基本反应原料,选择工业生产聚酰亚胺的方法,制备了一系列具有微孔和介孔结构的聚酰亚胺交联网络。这一合成策略区别于其他多孔聚酰亚胺的制备通常需要用到昂贵的具有空间立体结构的单体,而且反应在进行过程中没有用到任何有毒的溶剂和催化剂。此外,通过改变二酐单体的分子尺寸,可以有效控制聚合物网络的比表面积等孔结构性质。通过77K下的氮气吸附实验测得它们的最高比表面积可达660m2g-1。273K/1.13bar下能够吸附7.3wt%的C02。(3)直接以芳香杂环化合物——噻吩、吡咯、呋喃——为构筑单体,二甲氧基甲烷(FDA)为外交联剂,在温和的溶剂热条件下合成了一系列孔壁饰有大量杂原子的微孔聚合物材料,并结合计算机模拟研究了所合成材料的孔结构性能以及对C02气体的吸附行为。实验结果表明：尽管相比于其他微孔有机聚合物材料,所合成的这些微孔芳杂环网络的比表面积并不高(437～726m2g-1),但是却表现出优异的CO2吸附性能。在低覆盖下,CO2吸附热高达27～36kJmol-1。尤其是以吡咯为单体合成的聚合物网络Py-1,显示了超高的C02选择性吸附能力：在273K下,Py-1对CO2/N2的选择性高达117,这一选择性数据已居于目前世界报道的前列。(4)以路易斯酸为催化剂,在温和的条件下通过简单的一锅法偶联合成了含有卟啉结构的微孔聚合物网络PTPP。并利用卟啉环的配位作用,通过后合成改性法在所得聚合物网络中引入了镁、锌等过渡金属离子。研究结果发现,引入镁离子后能够增强材料的二氧化碳吸附性能。更多还原

【Abstract】 Global warming caused by large CO2emission has an alarming impact on the earth’s fragile environment. In order to stabilize the CO2concentrations in the atmosphere, carbon dioxide capture has attracted the interests of international in recent years, and the development of efficient methods for capturing CO2from industial flue gas has become an important issue. Microporous materials have potential applications for CO2capture due to many advantages such as low density, high specific surface areas and high porosity. Siginificant progress has been made in recent years on these materials, especially on the design and synthesis of microporous organic polymers (MOPs). To date, however, most monomers used in construction of the MOPs should be carefully designed and synthesized. Moreover, toxic solvents or/and catalysts are usually used during the reaction process. All these factors are prone to limit the wide use of the MOPs in industry. Therefore, the synthesis of cost-effective microporous polymers with high surface area is still a major challenge for chemists and materials scientists.The main task of this PhD thesis is to synthesized several hypercrosslinked polymers under mild reaction conditions by using cheap commercially chemicals as starting monomers. The polymers are characterized by solid-state13C NMR, N2gas sorption, and FT-IR spectroscopy. In addition, the CO2-capture applications of these porous organic compounds have also been studied. The main contents are listed as follows:(1) Two hypercrosslinked polymer networks has been synthesized by the self-condensation of bishydroxymethyl monomer,1,4-benzenedimethanol (BDM), and monohydroxymethyl compound, benzyl alcohol (BA). This is different from the previous reports that multifunctional monomers or crosslinkers is crucial for constructing the porous polymer networks. N2sorption isotherms for the polymers showed that both materials are predominantly microporous with the Brunauer-Emmett-Teller (BET) surface areas of847m2g-1for HCP-BDM and742m2g-1for HCP-BA. At273K/1bar, the CO2uptake was about12.6and8.46wt%for HCP-BDM and HCP-BA, respectively. Based on these results, this study opens up the possibility of synthesizing porous materials using the monofunctional monomers.(2) A series of porous polyimides with surface area up to660m2g-1have been synthesized by polycondensation of melamine and several readily available dianhydride monomers. Notably, the polymerization was carried out without toxic catalysts. Moreover, all of the starting compounds used in this study are low price, whereas other porous polyimides prepared often require expensive twisted (spiro type) or tetrahedral-based monomers. The environmental application of the polymers have also been investigated and it was found that PI1can adsorb7.3wt%CO2at273K/1.13bar.(3) The incorporation of heteroatoms into the porous polymers has the potential to increase the sorption and the selectivity for CO2. With this consideration in mind, we reported a facile and versatile strategy for preparing aromatic heterocycle-based microporous organic polymers. Unlike the elaborately designed monomers used in previous studies, all the heterocyclic molecules were directly crosslinked to form the highly porous networks by using formaldehyde dimethyl acetal (FDA) as external cross-linker. Considering their moderate surface areas, all these materials demonstrate ultrahigh CO2storage properties compared to other microporous with comparable surface area in the range of400～700m2g-1. Specifically, the network based on pyrrol (Py-1) shows an extraordinarily high selective adsorption of CO2over N2(about178at273K). To our knowledge, this value is the highest among all microporous materials reported to date.(4) The synthesis of a microporous organic polymer containing free-base porphyrin subunits has been accomplished by coupling the meso-tetraphenylporphyrin with Lewis acid as the catalyst. Metallation by post-synthesis modification affords microporous materials incorporating either Mg or Zn(porphyrins) that have been shown to be benifited to the CO2uptake.更多还原