二氧化碳合成碳酸酯催化剂的研究

发布时间：2018-09-18 20:29

【摘要】：二氧化碳作为一种温室气体,具有廉价、无毒、储量丰富等特点,将其高效、绿色地转化为高附加值化工产品,对于实现废弃资源的合理利用,减少温室气体排放具有重要意义,是科学界和工业界关注的热点。其中由二氧化碳和环氧丙烷合成碳酸丙烯酯的反应已经工业化,碳酸丙烯酯广泛应用于纺织、印染、电池、高分子合成等方面,同时在药物和精细化工中间体的合成中也占据重要的地位。通过国内外无数科研工作者们的研究探索,人们相继发现了金属、金属卤化物、金属氧化物、铵盐、膦盐、高分子类、离子液体等催化剂,但仍然存在以下问题:(1)催化剂的成本高但催化活性较低;(2)催化剂对空气敏感;(3)反应要借助有机溶剂;(4)反应过程要求较高温度和压力等,这些都是以后设计环加成催化剂时要解决和改进的地方。本课题旨在保证高效温和催化,开发出了两种催化体系。第一类为稀土金属卟啉配合物催化体系。本课题合成了不同种类的稀土金属卟啉催化剂,并使用元素分析、红外光谱、紫外光谱以及核磁共振等方法进行分析表征,证实了催化剂的成功合成。考察了稀土金属卟啉配合物用于二氧化碳与环氧丙烷的环加成反应的催化性能。⑴对环加成反应条件进行了优化,考察了不同温度、压力、反应时间对催化反应的影响,给出了催化反应的最佳条件,四苯基卟啉镱催化剂是在80℃,1.5MPa,不使用任何溶剂的情况下反应60 min的效果最好,产物收率可达93%。⑵对催化体系进行了优化,考察了不同稀土金属离子、不同助催化剂以及不同轴向配体对二氧化碳与环氧丙烷反应催化活性的影响。结果表明:(1)催化活性与金属离子的半径密切相关,金属离子半径越小,电荷密度越高,Lewis酸性越强,可以形成更加稳定的金属-配体的配位键,所以四苯基卟啉镥呈现最好的催化效果;(2)最优的助催化剂是四丁基溴化铵;(3)吸电子基有利于提高中心金属离子的路易斯酸性,所以轴向为氯取代的金属配合物能促进环氧丙烷的活化,提高产物的收率,最终氯代四苯基卟啉镱配合物作为催化剂时碳酸丙烯酯产率高达97%。⑶改变反应底物测试配合物的催化性能。增加反应底物环氧氯丙烷和环氧苯乙烷,以TPPYb/TBAB为催化体系,分别与二氧化碳进行环加成反应,都可以有效的转换成相应的有机碳酸酯,产物收率都在80%以上。结果表明该催化体系具有良好的通用性。第二类为金属串配合物催化体系。本文利用萘烧法以二吡嗪萘啶胺为配体合成了八个直线型金属串配合物[Ni_6(μ_6-dpznda)_4(Cl)_2](PF6)_2(1)、[Ni_6(μ_6-dpznda)_4(NCS)_2](PF6)_2(2)、Ni_5(μ_5-dpznda)_4Cl_2(3)、Ni_5(μ_5-dpznda)_4(NCS)_2(4)、Co_5(μ_5-dpznda)_4Cl_2(5)、Co_5(μ_5-dpznda)_4(NCS)_2(6)、Cr_5(μ_5-dpznda)_4Cl_2(7)、Cr_5(μ_5-dpznda)_4(NCS)_2(8),并通过红外光谱、质谱以及元素分析对配合物进行了表征。配合物分子是由四个配体以螺旋盘绕方式与金属原子配位,轴向配体与金属原子呈线性排列。然后将金属串配合物与四丁基溴化铵(TBAB)协同催化二氧化碳和环氧化物合成碳酸酯。催化结果表明:金属串配合物具有良好的催化活性,转化频率高达23964 h~(-1)。
[Abstract]:As a kind of greenhouse gas, carbon dioxide has the characteristics of low cost, non-toxicity and abundant reserves. Converting it into high value-added chemical products efficiently and greenly is of great significance for the rational utilization of waste resources and the reduction of greenhouse gas emissions. It is a hot spot in science and industry, in which carbon dioxide is combined with propylene oxide. Propylene carbonate has been widely used in textiles, printing and dyeing, batteries, polymer synthesis and so on. It also plays an important role in the synthesis of pharmaceutical and fine chemical intermediates. Catalysts, such as oxides, ammonium salts, phosphine salts, polymers, ionic liquids, still have the following problems: (1) high cost of catalysts but low catalytic activity; (2) catalysts are sensitive to air; (3) the reaction must rely on organic solvents; (4) the reaction process requires higher temperature and pressure, which are to be solved in the design of cycloaddition catalysts. Two catalytic systems have been developed to ensure high efficiency and mild catalysis. The first is the rare earth metalloporphyrin complex catalytic system. Different kinds of rare earth metalloporphyrin catalysts have been synthesized and characterized by elemental analysis, infrared spectroscopy, ultraviolet spectroscopy and nuclear magnetic resonance. The catalytic performance of rare earth metalloporphyrin complexes for cycloaddition of carbon dioxide with propylene oxide was investigated. _The reaction conditions were optimized. The effects of temperature, pressure and reaction time on the catalytic reaction were investigated. The optimum conditions for the catalytic reaction, ytterbium tetraphenylporphyrin, were given. The catalyst was prepared at 80 C, 1.5 MPa, without any solvent for 60 min. The yield of the product was 93%. _The catalytic system was optimized. The effects of different rare earth metal ions, different co-catalysts and different axial ligands on the catalytic activity of CO_2 to propylene oxide were investigated. The smaller the radius of metal ions, the higher the charge density, the stronger the Lewis acidity, and the more stable the metal-ligand coordination bonds can be formed, so the tetraphenylporphyrin lutetium exhibits the best catalytic effect; (2) the best co-catalyst is tetrabutylammonium bromide; (3) the electron-absorbing group is conducive to improving the central gold. Because of the Lewis acidity of metal ions, the axial CHLORINE-SUBSTITUTED metal complexes can promote the activation of propylene oxide and increase the yield of the product. The yield of propylene carbonate is up to 97% when the chlorotetraphenylporphyrin ytterbium complex is used as catalyst. _Change the catalytic performance of the reaction substrate to test the complex. Phenylethylene oxide, catalyzed by TPPYb/TBAB, can be effectively converted into corresponding organic carbonates by cycloaddition reaction with carbon dioxide. The yield of the product is more than 80%. The results show that the catalytic system has good versatility. The second kind is the metal chain complex catalytic system. 鍟惰兒涓洪厤浣撳悎鎴愪簡鍏釜鐩寸嚎鍨嬮噾灞炰覆閰嶅悎鐗Ni_6(渭_6-dpznda)_4(Cl)_2](PF6)_2(1),[Ni_6(渭_6-dpznda)_4(NCS)_2](PF6)_2(2),Ni_5(渭_5-dpznda)_4Cl_2(3),Ni_5(渭_5-dpznda)_4(NCS)_2(4),Co_5(渭_5-dpznda)_4Cl_2(5),Co_5(渭_5-dpznda)_4(NCS)_2(6),Cr_5(渭_5-dpznda)_4Cl_2(7),Cr_5(渭_5-dpznda)_4(NCS) The complexes were characterized by IR, MS and elemental analysis. Four ligands were spirally coiled with metal atoms, and the axial ligands were linearly arranged with metal atoms. Then the metal strings were synergistically catalyzed by tetrabutylammonium bromide (TBAB) to synthesize carbon dioxide and epoxides. Carbonate. Catalytic results show that metal complexes have good catalytic activity and the conversion frequency is as high as 23964 h~(-1).
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ225.52;O643.36

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