Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA.
Dalton Trans. 2012 Apr 14;41(14):3962-73. doi: 10.1039/c2dt11908k. Epub 2012 Feb 28.
The adsorption of ammonia in four metal-organic frameworks modified with different functional groups (-OH, -C=O, -Cl, -COOH) was investigated using a hierarchical molecular modeling approach. To describe the hydrogen bonding and other strong interactions between NH(3) and the surface functional groups, a set of Morse potential parameters were obtained by fitting to energies from quantum chemical calculations at the MP2 level of theory. We describe a systematic force field parameterization process, in which the Morse parameters were fitted using simulated annealing to match a large number of single-point MP2 energies at various distances and angles. The fitted potentials were then used in grand canonical Monte Carlo simulations to predict ammonia adsorption isotherms and heats of adsorption in functionalized MIL-47, IRMOF-1, IRMOF-10, and IRMOF-16. The results show that ammonia adsorption can be significantly enhanced by using materials with appropriate pore size, strongly interacting functional groups, and high density of functional groups.
采用层次分子建模方法研究了四种不同官能团（-OH、-C=O、-Cl、-COOH）修饰的金属有机骨架对氨的吸附。为了描述 NH(3)与表面官能团之间的氢键和其他强相互作用，通过拟合量子化学计算在 MP2 理论水平的能量，得到了一组 Morse 势能参数。我们描述了一个系统的力场参数化过程，其中使用模拟退火来拟合 Morse 参数，以匹配大量不同距离和角度的单点 MP2 能量。拟合后的势函数随后用于巨正则蒙特卡罗模拟，以预测功能化 MIL-47、IRMOF-1、IRMOF-10 和 IRMOF-16 中的氨吸附等温线和吸附热。结果表明，通过使用具有适当孔径、强相互作用官能团和高官能团密度的材料，可以显著增强氨的吸附。
