外电场诱导下多孔骨架材料气体吸附分离研究

This proposal focuses on study of the host-guest interaction caused by electric dipole/quadrupole and spin coupling between gas molecules and adsorptive sites on the porous framework materials under external electric field. In-situ X-ray or neutron diffraction/scattering technique will be employed to obtain the gas molecules’ adsorbed structures and intermolecular Coulomb interaction and magnetic interaction information. Essence of adsorption is caused by electromagnetic forces between molecules. When dipole or quadrupole is present in adsorbates or adsorption sites on the porous framework, changing the electric field strength or electric potential gradient will cause the splitting of molecular orbital energy level and then affect the adsorption. The adsorptive sites on the porous framework own an intrinsic magnetic moment when its orbit-spin coupling is not zero. When the adsorption sites owe intrinsic magnetic moment, the spin electrons orbital energy will change in external electric field, which affects the magnetic exchange energy between the adsorptive sites owing intrinsic magnetic moment and paramagnetic or diamagnetic molecules, finally changing the adsorptive amount. This application is intended to raise the mechanism of adsorption for a series of Fe(II), Mn(II), Co(II), Ni(II) and Cu(II) based metal-organic frameworks for O2, N2 and CO2 under external electric fields, and establish the mechanism of adsorption under external fields via in-situ experiments. This research might guide the development of the adsorbent, improve adsorption separation process and provide a reliable theoretical support for improving the efficiency of gas separation.

本项目拟开展外加电场诱导下多孔骨架材料的气体吸附与分离研究。吸附作用本质是分子之间的电磁作用，当吸附质或吸附剂的吸附位点存在偶极、四极时，改变电场强度或电势梯度会引起分子轨道能级劈裂进而影响吸附作用；而当吸附位点具有固有磁矩时，外加电场改变自旋电子轨道能级，从而影响主体固有磁矩与顺磁或抗磁分子之间的交换能，宏观上表现为吸附作用强度的改变。本项目将基于Fe、Mn、Co、Ni、Cu等金属的多孔金属有机骨架材料为主体，研究其外置电场下O2、N2、CO2等气体的吸附行为，分析外置电场中金属中心的轨道能级劈裂情况、自旋产生的固有磁矩等信息与吸附作用之间的关系，进行吸附构象解析，测定分子间作用力信息，建立外置电场作用下气体吸附机制。该研究成果将指导吸附剂的开发设计，及吸附分离工艺的改进，为实现高效气体分离提供可靠的理论支持和实验依据。

气体吸附分离的依赖于吸附剂上气体吸附机理的研究，由于对工业中要求产品高纯度且生产低成本，根源上需要开辟新的吸附技术。.本项目提出利用未配位的空轨道与电子给体结合，同时通过对骨架结构的官能化，与CO2的p轨道作用，在外加电场作用下进一步改变客体分子的极性、偶极/四极矩，诱导增强分子间库伦作用。同时，通过电场主客体原本兼并的自旋轨道发生劈裂，改变能级，提升吸附剂的吸附作用。即利用电场改变原子中的电子轨道能级或者分子间的作用。.本项目研究集中在对于MOFs中配体和配位模式的设计调节，利用结构对电子云密度进行调控，调整吸附剂的电子轨道能级的高低变化以及轨道对称性。并将所设计制备的多孔MOFs材料用于CO2、N2、Ar的静态吸附以及混合气体的动态穿透实验，计算吸附系数，对气体吸附机制进行研究。通过中子衍射，原位表征等揭示气体吸附的机理，制备MOF混合基质膜，研究成膜的应用以及气体分离作用机制。