Mechanism for Rapid Conversion of Amines to Ammonium Salts at the Air–Particle Interface
Mechanism for Rapid Conversion of Amines to Ammonium Salts at the Air–Particle Interface
复制标题
胺在空气与颗粒界面快速转化为铵盐的机制
DOI：
10.1021/jacs.0c12207
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发表时间：
2020
影响因子：
15
通讯作者：
Joseph S. Francisco
中科院分区：
文献类型：
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作者：
Weina Zhang;Jie Zhong;Qiuju Shi;Lei Gao;Yuemeng Ji;Guiying Li;Taicheng An;Joseph S. Francisco
采用经典分子动力学、Born-Oppenheimer分子动力学和量子化学计算相结合的方法，研究了硫酸浓度对甲胺、二甲胺和三甲胺在空气-颗粒界面非均相反应的影响.结果表明，这些胺蒸气的混合物可以积累在空气-颗粒界面，然后参与两种类型的非均相反应取决于SA浓度的含水颗粒。在高SA浓度下，胺被H3 O+中和并在仅几皮秒内形成铵盐。在低SA浓度下，胺主要通过水解反应进行，并产生铵和OH-的离子对。然而，所形成的离子对极不稳定，并且发生逆反应。考虑到在高SA浓度下胺的盐转化时间尺度比在低SA浓度下快2.5-15倍，胺在高酸性颗粒处的积累更有利。
The effect of sulfuric acid (SA) concentrations on heterogeneous reactions of amines such as methylamine (MA), dimethylamine (DMA), and trimethylamine (TMA) at the air–particle interface is investigated using combined classical molecular dynamics, Born–Oppenheimer molecular dynamics, and quantum chemical calculations. The results show that the mixtures of these amine vapors can accumulate at the air–particle interface and then participate in two types of heterogeneous reactions depending on the SA concentrations in the aqueous particles. At high SA concentrations, amines are neutralized by H3O+and form ammonium salts within only a few picoseconds. At low SA concentrations, amines mainly proceed by hydrolysis reactions and produce ionic pairs of ammonium and OH–. However, the formed ionic pair is extremely unstable, and the reverse reaction takes place. Considering that the salt conversion time scales of amines at high SA concentrations are 2.5–15 times faster than those at low SA concentration, amine accumulation at high acidity particles is more favored.