Computational Investigation of the Interaction of Multifunctionalized Porous Aromatic Frameworks with SO2

The adsorption of pure SO2, a sulfur-containing acid
gas, by porous aromatic frameworks (PAFs) was investigated with a
range of computational methods including first-principles density
functional theory and grand canonical Monte Carlo calculations. We
found that the presence of combinations of functional groups, including
the electron-donating groups −CH3, −OH, and
−NH2, and the electron-withdrawing groups −CN,
−COOH, and −NO2, within the PAF structures
was predicted to enhance SO2 uptake at low pressure. In
particular, the simulations predicted that the functionalized PAFs,
especially double-functionalized PAFs, PAF-(OH)2 and PAF-(COOH)2, as well as mixed-functionalized PAFs, PAF-2-CN-3-NO2 and PAF-3-OH-5-NH2, were able to capture high
loadings of SO2 pure gas under a very low pressure at 298
K. The additional functional groups were able to strengthen the interactions
between the PAF frameworks and the acid gas molecules. At the same
time, introducing two functional groups to PAFs generally decreases
the maximum adsorption limit, due to the smaller pore volume available
to the gases. In this work, we created a library of various functionalized
PAFs, as well as simulated their adsorption isotherms. The results
of this work can be used as a guideline for other combinations of
functionalized PAFs and their experimental synthesis for maximal acid
gas adsorption.

本研究采用多种计算方法，包括基于密度泛函理论的第一性原理和巨正则蒙特卡罗模拟，对纯二氧化硫（一种含硫酸性气体）在多孔芳香框架（PAFs）中的吸附作用进行了研究。研究发现，PAFs结构中存在多种官能团组合，包括供电子基团（如−CH3、−OH和−NH2）和吸电子基团（如−CN、−COOH和−NO2），这些组合能够预测在低压下提高二氧化硫的吸附量。特别是，模拟结果表明，功能化PAFs，尤其是双功能化PAFs（如PAF-(OH)2和PAF-(COOH)2）以及混合功能化PAFs（如PAF-2-CN-3-NO2和PAF-3-OH-5-NH2），在298 K的极低压力下能够捕获高浓度的二氧化硫纯气体。额外的官能团能够增强PAFs框架与酸性气体分子之间的相互作用。然而，将两个官能团引入PAFs通常会降低最大吸附量，这是因为可供气体使用的孔隙体积减少。在本研究中，我们构建了一个包含各种功能化PAFs的库，并模拟了它们的吸附等温线。本研究的结果可为其他功能化PAFs组合及其实验合成以实现最大酸性气体吸附提供指导。