从微乳界面统计力学分析到二氧化碳吸附材料合成

The purpose of this program is to develop a novel macroporous material for CO2 adsorption to circumvent some drawbacks of those ordinary materials, such as low amino loading, high amino leading, and low stress–strain. Here we prepare the material via emulsion polymerization, where polyethylenimine (PEI) enveloped nanoparticles as well as Tuwen80 act as the Pickering emulsifier to achieve the effect of uniform loading of nanoparticles and PEI chain embedding. By means of interfacial control and inorganic-organic composition, a spherical adsorbent can be synthesized with ordered macroporous structure with solid PEI loading, resulting in high adsorption/desorption efficiency in a fluidized-bed process. In order to achieve such effect, we first perform the initial experiments to determine the basic components, to characterize their structure and performance, and to find out organization direction. We then investigate the detailed interfacial structure and free-energy of the complicated system at molecular level to evaluate their influence to the size of microemulsion drops, the dispersion of PEI chains and nanoparticles on pore surface, and the final pore size distribution of adsorbent. As a result, a direct correlation of interfacial structure with the macroporous structure can be established to guide the experiment synthesis of high efficient adsorbent.

针对现有CO2吸附材料普遍存在的胺基负载率低、表面胺易挥发和脱落、机械强度低、耐磨性能差等问题，本项目以乳液聚合的方法实现大量胺基植入式负载，通过微乳界面调控和有机无机复合，合成具有规整孔结构、纳尺度粗糙孔表面的聚乙烯亚胺/纳米颗粒/聚丙烯酰胺球形颗粒，用于CO2捕集。在保证耐磨性能满足流化床运行的前提下，大幅度提高吸/脱附效率和循环周期。为实现上述目标，首先完成基本结构和性能的实验研究，确定颗粒、表面活性剂、水和油相基本选择；针对实验过程中发现的孔结构不均匀、颗粒和PEI分散程度不高的问题，从分子层面对结构形成的微观机理展开DFT研究，弄清有机-Pickering乳化-无机相界面不同组成、配比时的界面密度与能量分布，建立界面结构与材料结构的直接关联，评估液滴内微乳相的界面结构和表面张力对材料孔道结构、PEI负载方式和颗粒分散的影响，由此形成界面调控机制，指导合成高性能的CO2吸附。

本项目基于分子动力学模拟和量化计算，明确了由丙烯酸酯形成的油包水乳液组成与界面张力对聚丙烯酸酯基体孔结构、骨架强度和疏水性能的影响规律；基于乳液悬浮聚合和有机胺接枝与改性，制备了胺基功能化聚丙烯酸酯球形颗粒复合材料，呈规整有序的互联互通大孔结构，孔表面为纳尺度粗糙结构，表面丰富的环氧基团提供了较高的有机胺接枝率，并通过对接枝有机胺进行环氧改性后，降低了脱附温度，可有效解决有机胺的溶解、氧化和高温失活等问题；测试表明，复合材料对CO2吸/脱附热力学、动力学、循环稳定性、抗杂质干扰能力等均达到或超过预期目标。在此基础上，开展了复合材料的吨级规模化规制备研究，完成3吨复合材料制备，用于燃煤烟气碳捕集工程验证，使基础研究具有实际工业应用价值。.本项目规模化制备胺基功能化复合材料的关键性能指标：堆积密度0.4 g/ml；平均粒径0.4~0.8mm；平均孔径1-5μm；抗压强度20 MPa；改性有机胺负载率75%；水润湿角103º；在模拟烟气条件下，复合材料工作吸附量达0.8 mmol/g，运行1500次后，吸附容量损失率低于5.0 %，具备工业化应用基础。