设计利用光调控吸着强度的CO2捕获材料

Reducing the emission of greenhouse gases like CO2 requires efficient and reusable capture materials. The energy for regenerating the capture media is crucial to the cost of CO2 capture. In this proposal, we target flue gases from stationary CO2 sources such as coal powerplants. Starting from electronic structures of capture materials and CO2, and empolying a macroscopic Langmuir-type adsorption model, we design CO2 capture model systems with photoswitchable CO2 sorption (adsorption and absorption). The model systems feature the conjunction of Lewis bases that can covalently bond with CO2 and azo-based backbones that can switch conformations upon light stimulation. Thus by regulating the conformation of the CO2-sorbent complex, differences in structures and local chemical environments of the cis and trans conformations can be utilized. As a result, the sorption strength between CO2 and capture materials can be controlled. We hope by taking advantage of light energy, the cost of CO2 capture can be lowered, i.e., capture CO2 with the strong CO2-sorbent interacting conformation, then switch the conformation by light, and finally release CO2 with the weak CO2-sorbent interacting conformation. We will integrate these sorption prototypes into ionic liquids, porous solids, etc. Meanwhile, these models might be applied in the capture of other acidic gases (SO2, NOx, etc.).

减少CO2等温室气体的排放需要高效、可循环使用的捕获材料。用来再生捕获材料的能耗高低是决定捕获成本的重要因素。本项目以CO2固定排放源（如火力发电厂）的烟气为目标，计划从捕获材料与CO2的电子结构出发，结合宏观的兰缪尔吸附模型，设计可由光调控CO2与捕获材料的作用强度的新型吸着（吸附、吸收）模型体系。该体系结合了能跟CO2形成共价键的路易斯碱和能够光响应构象变化的偶氮骨架。通过光调节CO2--捕获材料复合物的构象，利用其顺、反构象的几何结构和局部化学环境的差异，调控CO2的吸着强度。我们希望能够利用光能减少CO2捕获的能耗，即在吸着作用强的构象下吸收CO2，然后通过光控改变构象，再在吸着作用弱的构象下释放CO2。我们将把这类模型体系引入离子液体、多孔固体等材料。同时这些模型体系有可能被用于其他酸性气体（SO2、NOx等等）的捕获。

本研究采用基于电子结构计算的多尺度模拟方法，设计、筛选了一系列新型针对CO2等酸性气体的可逆的吸着材料。这些材料含有偶氮结构单元，能够对可见光进行响应、调整结构。调整前后的结构对于酸性气体的吸着强度有明显差异，因此可以实现利用可见光调节吸着强度，减少吸着材料再生能耗的目的。本研究还分别研究了阳离子对吸着材料的影响，开发设计了新型的叁齿枝状吸着材料体系，以及考察了二维多孔材料对酸性气体的分离效果。