湿法再生技术中水汽对CO2吸附的多重影响机制研究

In light of the high energy consumption problem during the process of CO2 separation with traditional thermal swing sorbents, a novel idea of CO2 separation using moisture swing adsorption technology is presented in the project. Driven by the issue of poor environmental adaptability and the urgent need to explore the adsorption mechanism at the interface for the moisture swing sorbents, the microscopic mechanism of the interactions at interface, substance transfer and energy conversion during the process of adsorption will be studied in the project. Based on the advanced interface characterization techniques, the substance transfer process of CO2 and H2O happening at the interface is accurately depicted, and the structure and bond change between molecules at the interface is studied by adjusting the hydration degree. The mechanism of moisture swing adsorption is expected to be revealed from micro perspective. By combining the spectrographic studies of interface and the macroscopic thermodynamic analysis, a thermodynamic model based on the equilibria of substance and chemical energy of the system is going to be developed. The mechanism of interactions between hydration water and CO2 adsorption is studied from macro perspective. The reaction path of moisture swing adsorption is explored through kinetic research, and the unique impact of moisture on reaction path can be explored. Finally, based on the reveal of mechanism, the moisture effect on CO2 adsorption is studied for different materials which are categorized by material properties and interface properties. The rule for developing adsorbent material and support material with best match of low cost and high adsorption rate under certain working conditions will be suggested.

针对传统热再生材料分离CO2过程中能耗高等问题，本项目提出了采用湿法再生吸附分离CO2的新思路。针对当前湿法再生吸附环境适应性较差，界面吸附机理认识不清的问题，本项目将对湿法再生吸附过程的界面微观作用机制及吸附过程中的物质迁移及能量转化规律进行研究。在先进界面表征技术基础上，对CO2与H2O在界面吸附过程中发生的物质迁移过程进行精确刻画，并研究随水合度的调节，界面化学结构的演变规律，从微观角度揭示湿法再生吸附的机理。通过将宏观热力学分析手段与物质迁移的微观光谱分析相结合，建立基于系统中物质量和化学势能的热力学模型，从宏观角度研究界面水对CO2吸附的影响机理。通过动力学研究，探索湿法再生吸附的反应路径，揭示水汽对反应路径的影响。最后，基于对机理的揭示，对吸附剂进行分类（材料，界面属性）研究水汽对吸附CO2的调控规律，探索适应不同应用环境的低能耗与高吸附率匹配的吸附剂及载体遴选准则

针对传统热再生材料分离CO2过程中能耗高等问题，本项目提出了采用湿法再生吸附分离CO2的新思路。针对当前湿法再生吸附环境适应性较差，界面吸附机理认识不清的问题，本项目开展了湿法再生吸附过程的界面微观作用机制及吸附过程中的物质迁移及能量转化规律的研究。通过宏观热力学分析手段，构建了“CO2-H2O-吸附剂”的多组分平衡模型并搭建了等温、等湿吸附实验平台，揭示了水汽作用下季胺聚合物型吸附剂吸附CO2伴随的水迁移现象并获得了定量表达。构建了从头计算的量子化学计算模型研究了CO2与H2O在界面吸附过程中的微观作用，刻画了吸附剂界面的质子转移路径，获得了季胺与氢氧根、碳酸根等的离子对结构特征及水合水与界面官能团的作用规律，确定了反应过渡态及“H2O质子转移--OH-吸附CO2”的反应路径并获得了反应活化能（34.6kJ/mol），揭示了活化能受界面水的影响规律。吸附动力学方面，构建了基于改性缩核模型的CO2吸附传质模型，揭示了扩散控制的吸附动力学。开发了旋转床动力学实验台并开展了动力学测试，获得了不同结构参数、温度、湿度等条件下的扩散传质系数，反应速率常数等动力学参数；结果表明相同相对湿度下，温度越高，吸收动力学越佳而相对湿度对化学反应速率的影响更加明显，得到吸附化学反应活化能为31.7kJ/mol。最后，在对传质动力学及其影响因素机理揭示的基础上，基于相转化法开发了界面结构可控的季胺基聚合物吸附剂，获得了吸附剂结构参数（膜厚，掺混比，孔隙尺寸）及化学属性（骨架结构，官能团）等的优化方案，优化后材料的动力学性能可提升30%以上，进一步的降低吸附剂粒径可使得半吸附时间小于40分钟，与已报道的金属框架材料（MOF）的吸附动力学相当。本项目的研究，有望为新型CO2捕集工艺，包括空气CO2直接捕集工艺，提供一种高动力学性能的吸附剂，从而大幅降低CO2捕集成本。