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酸性离子液体基Zr-MOF的合成及其催化性能研究
徐子晨
Subtype硕士
Thesis Advisor赵国英
2018-07
Degree Grantor中国科学院研究生院
Degree Name硕士
Degree Discipline化学工程
Keyword金属有机框架材料,离子液体,固载化,酯化反应,疏水性修饰
Abstract

与常规的分子溶剂相比,离子液体(Ionic Liuqids,ILs)具有良好的导电性、宽泛的液态范围、阴阳离子的可设计性、强静电场、独特的微环境和多重微观作用力(氢键、静电、范德华力等)等优良特性。作为21世纪最热门的材料之一,金属有机框架(Metal-Organic Framework,MOF)材料,因其具有高比表面积、大孔隙率、低密度、结构可调和化学功能丰富等独特的性质,被广泛认为在气体储存和分离、多相催化和药物缓释等领域具有重要应用潜力。利用MOF材料对离子液体进行固载可以将离子液体和MOF材料各自优势在限域空间内协同集合,既能够克服离子液体粘度大和传质慢等问题,又可以拓展MOF材料的功能与用途,有望推动一个新兴学科领域的发展。本论文首先利用溶剂热的方法合成了含有2,2’-联吡啶基团的Zr-MOF材料(UiO-67-bpy),然后通过联吡啶基团和Br?nsted酸的酸碱中和反应,引入离子液体基团,最终合成了三种酸性离子液体基Zr-MOF。对材料进行了系统的表征,并考察了材料在乙酸和异辛醇酯化反应中的催化性能。然后通过PDMS和GO对材料进行疏水性修饰以进一步提高其催化性能和稳定性。具体研究如下:(1)采用溶剂热及后功能修饰的方法设计合成了三种酸性离子液体基Zr-MOF(UiO-67-HSO4,UiO-67-CF3SO3,UiO-67-hifpOSO3)。材料的表征结果表明:三种材料均成功制备且原始材料的形貌基本保留下来,酸性离子液体基团能够均匀分布在材料中,每一个2,2’-联吡啶基团嫁接一个酸性离子液体基团。材料还具有较高的比表面积和较大的孔径,并且具有良好的热稳定性。(2)用乙酸和异辛醇的酯化反应作为模型反应,研究了三种材料的催化性能。在相同的反应条件下,具有最佳催化性能的是UiO-67-CF3SO3,以该材料对反应条件进一步优化,在优化的反应条件下,异辛醇的转化率可达98.6%,且材料重复使用5次后其催化活性变化不大。此外,UiO-67-CF3SO3在其他酸和醇为反应物的酯化反应中也表现出良好的催化性能,醇的转化率均达到85%以上。(3)利用PDMS和GO制备了两种疏水性修饰的UiO-67-CF3SO3材料,PDMS@UiO-67-CF3SO3和rGO@UiO-67-CF3SO3。接触角测试的结果表明,rGO@UiO-67-CF3SO3疏水性能提高较低,而PDMS@UiO-67-CF3SO3具有良好的疏水性。对PDMS@UiO-67-CF3SO3进一步表征可知,PDMS对材料的物化性质影响不大,仍能保证反应物和产物的自由进出,同时材料也有较高的热稳定性。(4)研究了PDMS@UiO-67-CF3SO3在乙酸和异辛醇酯化反应中的催化性能。结果发现,PDMS@UiO-67-CF3SO3可以缩短反应进行的时间,在4 h时异辛醇的转化率即能达到98.3%。该材料在重复使用5次后其催化活性没有明显变化,原始形貌能基本保留下来。此外,PDMS@UiO-67-CF3SO3在其他酸和醇的酯化反应中也具有良好的催化效果,醇的转化率均可以达到80%以上。;Compared with conventional molecular solvents, ionic liquids (ILs) have the excellent characteristics of good conductivity, wide liquid range, designability of anions and cations, strong electrostatic field, unique microenvironment and multiple microscopic forces (hydrogen bond, static electricity, van der Waals forces). Metal-organic framework (MOF) materials as one of the hottest materials in the 21st century, have shown important potential applications in the fields of gas storage and separation, heterogeneous catalysis and drug release, because of their unique properties of high surface area, large porosity, adjustable structure and rich chemical functions. Using MOF to immobilize ILs will combine the advantages of ILs and MOF in a confined space, which not only overcome the problems of large viscosity and slow mass transfer of ionic liquids, but also expand the functions and applications of MOF, that may promote the development of an emerging discipline.Herein, a Zr-MOF material UiO-67-bpy that has 2,2’-bipyridine groups was synthesized by solvothermal method, then through the acid-base neutralization of the 2,2’-bipyridine moieties and Br?nsted acids to introduce ionic liquid groups for synthesizing acidic ionic liquid based Zr-MOF, characterizing the structure of the resulting materials systematically and exploring their catalytic performance in the esterification of acetic acid and isooctyl alcohol. Then, using PDMS and GO to improve the hydrophobic property of the resulting materials in orther to improve their catalytic performance and stability. The main research contents were summarized as follows: (1) Solvothermal method and post-functionalization method were used to synthesize three acidic ionic liquid based Zr-MOF (UiO-67-HSO4, UiO-67-CF3SO3 and UiO-67-hifpOSO3). The characterization results showed that these materials were synthesized successfully and the primary morphology was still maintained. The acidic ionic liquid groups were distributed in the materials uniformly, each 2,2’-bipyridine moiety of UiO-67-bpy was grafted to one acidic ILs group. Meanwhile, the materials maintained high surface area, large pore volume and good thermal stability. (2) The esterification of acetic acid with isooctyl alcohol was used as model reaction to probe the catalytic performance of the prepared materials. Under the same reaction conditions, UiO-67-CF3SO3 shown the best catalytic performance and the reaction conditions were further optimized by UiO-67-CF3SO3. Under optimized conditions, the conversion of isooctyl alcohol could reach 98.6% and it could be reused 5 times with no obvious reduction in catalytic performance. Moreover, UiO-67-CF3SO3 showed good catalytic performance in other esterification that with different acids and alcohols as reactants, the conversion of alcohols was more than 85%.(3) PDMS and GO were used to synthesize hydrophobic modified UiO-67-CF3SO3, PDMS@UiO-67-CF3SO3 and rGO@UiO-67-CF3SO3. Contact angle test showed that rGO@UiO-67-CF3SO3 had relative low hydrophobic property, but PDMS@UiO-67-CF3SO3 had high hydrophobicity. Further characterization of PDMS@UiO-67-CF3SO3 demonstrated that PDMS had almost no effect on the physicochemical properties of the material, the resulting material could make sure the free diffusion of reactants and products, and the material also had high thermal stability. (4) The catalytic performance of PDMS@UiO-67-CF3SO3 in the esterification of acetic acid with isooctyl alcohol had been investigated. The results showed that the reaction time could be reduced significantly by PDMS@UiO-67-CF3SO3, the conversion of isooctyl alcohol could reach 98.3% after 4 h. The material could be reused 5 times with no obvious reduction in catalytic performance, and the primary morphology could be maintained. Moreover, PDMS@UiO-67-CF3SO3 also showed good catalytic performance in other esterification that with different acids and alcohols as reactants, the conversion of alcohols was more than 80%.Key words: Metal-Organic Framework, Ionic Liquids, Immobilization, Esterification, Hydrophobic modification 

Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/26850
Collection中国科学院过程工程研究所
研究所(批量导入)
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GB/T 7714
徐子晨. 酸性离子液体基Zr-MOF的合成及其催化性能研究[D]. 中国科学院研究生院,2018.
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