基于金属有机框架材料的固态胺吸附剂设计和CO2吸附机理研究

Solid amine adsorbents with the characteristics of desirable adsorption capacity, high selectivity, and low regeneration energy have been paid much attention to their application for CO2 capture from flue gases. The challenge for development of polyamine impregnated solid amine sorbents is the aggregation of viscous polyamines in the pores of supports in the case of high amine loading, causing the increase of intra-particle diffusion resistance. Correspondingly, adsorption performance could not be further improved. The aim of this project is to design a new type of metal-organic frameworks (MOFs) based solid amine adsorbents. Various types of polyamines along with the additives are impregnated into MOF porous materials with large pore diameter, high pore volume and surface area. The additives of polyalcohol and alkanolamine function as the polyamine “plasticizer”, whereby the intra or inter chain interaction of polyamines is expected to be reduced. This plasticizing effect could improve the dispersity of polyamines in porous supports and reduce the intra-particle diffusion resistance, thereby, dramatically improving CO2 adsorption performance. The presence of both hydroxyl group and amine groups in alkanolamine is expected to exhibit synergetic effects on adsorption performance of solid amine adsorbents. The project will clarify the nature of promoting effects of additives via analysis of sorbent morphology, CO2 adsorption thermodynamics and kinetics. Mechanism of CO2 adsorption is thoroughly investigated to understand the effects of additives on the interaction of CO2 with amine groups. The work in this project provides a novel strategy to prepare a new type of efficient solid amine adsorbents.

固态胺吸附剂具有吸附容量高、选择性高、再生能耗低等特点，在捕集烟气中CO2研究领域备受关注。然而浸渍法制备的固态胺在高胺基负载量的情况下易发生聚胺分子团聚，增大了CO2内扩散阻力，使吸附性能难以进一步提高。本项目旨在设计一类以大孔径、大孔容及大比表面积的金属有机框架材料（MOFs）为基体的高效固态胺吸附剂，通过浸渍法实现多元醇、烷醇胺类添加剂与聚胺分子在MOF基体上共负载，利用多元醇对聚胺的增塑作用减弱聚胺分子间作用力，提高其在载体内分散度，从而降低CO2内扩散阻力，显著提高固态胺吸附性能。烷醇胺中的羟基和胺基协同作用有望进一步促进固态胺的吸附能力。结合吸附剂微观孔结构和形貌分析以及CO2吸附热力学、动力学研究，揭示添加剂提高吸附剂吸附性能的本质，并深入探讨CO2吸附机理,考察添加剂对CO2与胺基相互作用机制的影响。该项目为开发新一代高效固态胺吸附剂提供新思路。

减少碳排放，研发低碳技术是推进低碳经济发展的重要举措，本课题针对这一热点问题，开展了新型CO2捕集技术的研究工作，旨在开发新型低能耗、低成本的高效CO2分离技术。本研究工作首先开发了可用于烟气中CO2捕集的固态胺吸附剂，通过浸渍法实现二乙醇胺（DEA）以及SPAN80添加剂与聚乙烯亚胺分子（PEI）在MIL-101以及介孔二氧化硅基体上共负载，有效调控了CO2在吸附材料中的动力学扩散行为，使得固态胺吸附剂的CO2吸附能力显著提高，其中MIL-101/ PEI/ DEA吸附剂的吸附容量高达3.1 mmol/g。研究结果表明该扩散行为控制理念具有普适性，可广泛适用于各种载体包括MIL-101以及多种商业化二氧化硅材料。除此之外，我们成功开发了基于NH2-MIL-53的膜材料，通过控制NH2-MIL-53的负载量实现膜分离性能的优化，从而显著提高了CO2的分离效率。利用聚合物基体中含N碱性基团与NH2-MIL-53分子间的相互作用，增强两相相容性，有效抑制膜材料中缺陷结构的形成以及CO2对膜材料的塑化溶胀作用，该材料在二氧化碳捕集领域有广阔的应用前景。本项目研究成果为高效低能耗CO2捕集技术的发展具有重要的推动意义。