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功能化离子液体催化醇解PET的过程研究
Alternative TitleStudy on the process of poly(ethylene terephthalate) glycolysis catalyzed by functional ionic liquids
王倩
Subtype博士
Thesis Advisor张锁江
2013-05-01
Degree Grantor中国科学院研究生院
Degree Discipline化学工艺
Keyword聚对苯二甲酸乙二醇酯   功能化离子液体   催化醇解   反应过程   机理
Abstract聚对苯二甲酸乙二醇酯(PET)作为一种多功能热塑性材料,在我们的日常生活中有着非常广泛的应用,由于年消费量巨大,伴随而来的废旧PET的排放已经造成了严重的环境污染和资源浪费。回收再利用废旧PET不仅可以减少环境污染,而且可以延长资源的利用周期,产生巨大的社会和经济效益。 功能化离子液体作为新兴溶剂,在催化、合成和分离等领域展现了广阔的应用前景,已经成为国内外研究的热点。本论文针对化学回收方法中反应条件苛刻、单体选择性低和反应速率慢的问题,以功能化离子液体为基础,开发了一系列新的PET催化降解体系。主要创新性工作和成果如下: (1) 研究了第一过渡系金属离子液体催化醇解PET的反应。研究发现,第一过渡系金属离子液体具有高的热稳定性并可用于PET的催化醇解反应以获得高纯度的单体对苯二甲酸乙二醇酯(BHET)。其中,[bmim]2[CoCl4]和[bmim]2[ZnCl4]展示了较高的催化活性。优化了PET催化降解过程中的工艺参数并获取了最佳工艺条件。循环实验表明,[bmim]2[CoCl4]和溶剂乙二醇在循环六次后,其活性没有降低。高的催化活性主要是因为离子液体阴、阳离子间的协同催化作用。 (2) 研究了1-烯丙基-3-甲基咪唑类功能化离子液体催化醇解PET的反应。结果表明,[amim][ZnCl3]和[amim][CoCl3]的催化活性最高。GC-MS、NMR、ESI-MS和HPLC等多种表征手段表明主产物为BHET单体,纯度较高。催化机理研究表明,降解反应主要发生在PET颗粒的表面,高的催化活性主要是由于离子液体阴、阳离子间的协同催化作用和烯丙基引起的缺电子结构所致。 (3) 尿素作为催化剂用于PET的醇解反应中,展示了较高的催化活性,能够在温和的条件下有效地把废旧PET解聚为高纯度的BHET单体。尿素在循环十次后,催化活性没有降低。通过原位红外、实验和量化计算相结合的方式探讨了氢键在PET催化醇解过程中的作用,发现氢键的形成能够激活乙二醇,促进PET醇解。合成了一系列的能够与乙二醇形成氢键的氨基酸功能化离子液体并用于PET醇解反应,进一步验证了氢键作用机理。 (4) 设计开发了多个系列的双组分混合催化体系,在温和的条件下实现PET的快速降解且可催化降解各种不同类型的PET瓶,获得高纯度的BHET单体,发现高的催化活性主要是因为尿素与金属盐中金属离子间的协同催化作用。优化了降解反应的工艺参数,获得了最佳降解条件。对比实验发现,含结晶水金属盐不会降低其催化活性,从而有效降低催化剂成本。 (5) 合成了三类低共熔离子液体并测定了其凝固点曲线。发现由于组分尿素与金属盐之间发生了配位作用,造成其凝固点降低。考察了合成的低共熔离子液体在PET醇解过程中的催化活性。研究结果表明,该体系可以在温和的条件下实现PET的快速降解,得到高纯度的BHET单体。优化了反应过程的工艺参数并获取了最佳降解条件,在170 ℃反应30 min,PET可完全降解,选择性达83 %。在实验结果、量化计算和催化剂的设计合成与活性分析的基础上,提出了更加详实的催化机理,高的催化活性主要是尿素的氢键作用与金属离子的配位作用进行协同催化的结果。
Other AbstractAs a versatile thermoplastic material, poly(ethylene terephthalate) (PET) are widely used in our life. PET wastes have become a major challenge for the preservation of resource and protection of environment due to the large consumption. The recycling of PET wastes can not only reduce the damages to environment, but also prolong the cycle of resource utilization, which will bring great social and economic benefits. Functional ionic liquids (ILs), as a new solvent, show a broad application prospect in catalysis, synthesis and separation, and have become a research hotspot at home and abroad. The dissertation explores series of novel catalytic degradation systems of PET based on the functional ILs to overcome the problems of severe reaction condition, slow reaction rate and low monomer selectivity in chemical recycling. The main innovative work and achievements are as follows, (1) PET glycolysis catalyzed by first-row transition metal-containing ILs is studied. The results show that the synthesized ILs have good thermal stability and can be used in the catalytic glycolysis of PET to obtain high pure monomer bis(hydroxyethyl) terephthalate (BHET). Among them, [bmim]2[CoCl4] and [bmim]2[ZnCl4] exhibit higher catalytic activity. The influences of experimental parameters on the PET degradation are investigated and the optimization condition is obtained. Recycling result shows that [bmim]2[CoCl4] and ethylene glycol (EG) work efficiently after being used for six times. The interaction between EG and catalyst plays an important role in the glycolysis process and the high catalytic activity is mainly attributed to the synergistic effect of cation and anion of IL catalyst. (2) PET glycolysis catalyzed by 1-allyl-3-methylimidazolium halo-metallate ILs is studied. The results show that [amim][ZnCl3] and [amim][CoCl3] exhibit higher catalytic activity under mild reaction condition. All kinds of characterizations, such as GC-MS, NMR, ESI-MS and HPLC show that the main degradation product is BHET and has a high purity. The study on the catalytic mechanism shows that the degradation reaction mainly takes place on the surface of PET pellets, and that the high catalytic activity is attributed to the synergistic effect of cation and anion of IL and the electron-deficient structure caused by alkyl group.
Pages129
Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/8293
Collection研究所(批量导入)
Recommended Citation
GB/T 7714
王倩. 功能化离子液体催化醇解PET的过程研究[D]. 中国科学院研究生院,2013.
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