Atmospheric chemistry of CH3CHO: the hydrolysis of CH3CHO catalyzed by H2SO4
Atmospheric chemistry of CH3CHO: the hydrolysis of CH3CHO catalyzed by H2SO4
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CH3CHO 的大气化学：H2SO4 催化 CH3CHO 的水解
DOI：
10.1039/c7cp07312g
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发表时间：
2018
影响因子：
3.3
通讯作者：
Mitchell Ellen
中科院分区：
文献类型：
--
作者：
Tan Xing-Feng;Long Bo;Ren Da-Sen;Zhang Wei-Jun;Long Zheng-Wen;Mitchell Ellen
阐明大气氧化机制和大气化合物的反应动力学对于大气模拟和了解大气有机气溶胶的形成具有重要意义和必要性。虽然在硫酸存在下检测到醛的水解，但反应机制和动力学仍不清楚。在此，我们采用CCSD(T)/CBS精度的电子结构方法和规范变分过渡态理论结合小曲率隧道效应研究CH3CHO水解的反应机理和动力学。计算结果表明，CH3CHO的水解需要克服37.21 kcal mol−1的能垒，而在硫酸催化剂的作用下，能垒降低至-9.79 kcal mol−1。此外，计算的动力学结果表明H2SO4⋯H2O + CH3CHO反应比H2SO4 + CH3CHO⋯H2O反应更快。此外，当 OH、H2SO4 和 H2O 浓度分别为 104、108 和 1017 分子 cm−3 时，H2SO4⋯H2O + CH3CHO 反应可以在夜间发生的 CH3CHO 下沉到 260 K 以下的过程中发挥重要作用，因为它可以与 CH3CHO + OH 反应很好地竞争。这些发现对大气化学具有广泛的影响，因为 H2SO4 对大气中 CH3CHO 的水解和二次有机气溶胶的形成具有潜在的重要性。
Elucidating atmospheric oxidation mechanisms and the reaction kinetics of atmospheric compounds is of great importance and necessary for atmospheric modeling and the understanding of the formation of atmospheric organic aerosols. While the hydrolysis of aldehydes has been detected in the presence of sulfuric acid, the reaction mechanism and kinetics remain unclear. Herein, we use electronic structure methods with CCSD(T)/CBS accuracy and canonical variational transition state theory combined with small-curvature tunneling to study the reaction mechanism and kinetics of the hydrolysis of CH3CHO. The calculated results show that the hydrolysis of CH3CHO needs to overcome an energy barrier of 37.21 kcal mol−1, while the energy barrier is decreased to −9.79 kcal mol−1 with a sulfuric acid catalyst. In addition, the calculated kinetic results show that the H2SO4⋯H2O + CH3CHO reaction is faster than H2SO4 + CH3CHO⋯H2O. Additionally, the H2SO4⋯H2O + CH3CHO reaction can play an important role in the sink of CH3CHO below 260 K occurring during the night period when OH, H2SO4, and H2O concentrations are 104, 108, and 1017 molecules cm−3, respectively, because it can compete well with the CH3CHO + OH reaction. There are wide implications in atmospheric chemistry from these findings because of the potential importance of the catalytic effect of H2SO4 on the hydrolysis of CH3CHO in the atmosphere and in the formation of secondary organic aerosols.