均相与多相催化剂在CO2环加成反应中的研究进展

Research progress of homogeneous and heterogeneous catalysts in CO2 cycloaddition reactions

  • 摘要: 二氧化碳(CO2)是一种主要的人为温室气体,主要由化学、热电和钢铁工业以及运输等部门产生。大气层中CO2浓度的增加是导致诸多环境问题的主要原因,如全球变暖、海平面上升和全球气温升高。然而,CO2作为一种可再生、廉价和无毒的化学原料,可用来生产具有高附加值的化学品,进而降低碳浓度。五元环碳酸酯由于其优越的物理化学特性,如高沸点、高偶极矩和生物降解等性能而被广泛应用。由环氧化合物和CO2合成环碳酸酯是迄今为止研究较多的方法。然而,由于CO2的高热稳定性和动力学惰性,使其作为反应原料需要大量的能量投入,可能导致的结果是CO2浓度是一个净增长过程。因此,利用CO2作为C1构筑单元是一个长期的挑战。本工作基于CO2固定反应机制,概述了各种类型的均相和多相催化剂在CO2固定反应合成精细化学品环状碳酸酯中的研究进展,包括有机催化剂、离子液体、金属有机框架化合物、多孔有机聚合物等。目前,几乎所有类别催化剂均可以在室温和低压力下,以实验室规模成功地使用纯CO2将其固定到末端环氧化合物上,对于非末端环氧化合物通过更高的温度和压力以实现相应转化。同时,分析了催化剂在多取代环氧化合物或生物衍生环氧化合物转化、低浓度CO2转化和实现工业化三个方面所面临的挑战,并提出了未来相关研究努力的方向。

     

    Abstract: Carbon dioxide (CO2) is a major anthropogenic greenhouse gas produced by chemical, thermoelectric and steel industries as well as transport sector. The increasing concentration of CO2 in atmosphere is responsible for plenty of environmental problems such as global warming, rising sea levels and increasing global temperatures. However, CO2 could consider as renewable, cheap and non-toxic chemical raw material, using CO2 to produce high value-added chemicals to reduce carbon concentrations is a highly desirable strategy. Five-membered cyclic carbonates have a wide range of applications due to their superior physicochemical properties such as high boiling point, high dipole moment and biodegradability. The synthesis of cyclic carbonates from epoxides and CO2 is by far the most approved method. Nevertheless, due to high thermal stability and kinetic inertness, it is necessary to activate CO2 as feedstock for organic synthesis with large energy, which may result in the release of more CO2 than is actually. Therefore, the use of CO2 as C1 building block is long-term challenged. This paper outlines the progress of research on various types of homogeneous and heterogeneous catalysts for CO2 fixation to generate cyclic carbonates, including organocatalysts, ionic liquids, metal-organic frameworks, and porous organic polymers. Almost all of these catalysts are currently available for the successful fixation of CO2 to terminal epoxides on laboratory scale using pure CO2 at ambient temperatures. For internal epoxides higher reaction conditions are usually required to achieve the desired conversion. It was analyzed three areas of present major challenges in catalyzing multi-substituted epoxides or bio-derived epoxides, diluted CO2 conversion and industrialization, and the directions for future research efforts on the subject were suggested.

     

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