Self-Catalytic Reaction of SO3 and NH3 To Produce Sulfamic Acid and Its Implication to Atmospheric Particle Formation
Self-Catalytic Reaction of SO3 and NH3 To Produce Sulfamic Acid and Its Implication to Atmospheric Particle Formation
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DOI：
10.1021/jacs.8b04928
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发表时间：
2018-09-05
影响因子：
15
通讯作者：
Zeng, Xiao Cheng
中科院分区：
文献类型：
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作者：
Li, Hao;Zhong, Jie;Zeng, Xiao Cheng
三氧化硫（SO3）是大气中最活跃的化学物质之一，其在大气中的命运对空气质量和人类健康有着深远的影响。一般认为 SO3 的主要气相损失途径是与水分子反应，产生硫酸。后者被视为新粒子形成（NPF）的关键组成部分。本文确定了在存在丰富的气相氨 (NH3) 物质的情况下 SO3 的一种新的竞争性损失途径。具体来说，SO3和NH3之间的反应生成氨基磺酸，可以通过反应物(NH3)进行自催化。在NH3浓度相对较高的干燥和严重污染地区，通过这种新的SO3损失途径，双分子SO3-NH3反应的有效速率常数可以足够快，从而与传统的SO3与水损失途径相比具有竞争力。此外，这项研究表明，反应的最终产物，即氨基磺酸，可以将硫酸和二甲胺 (DMA) 的 NPF 最快速率提高约 2 倍。提出了大气中酸碱聚集稳定剂的替代来源，这种新的 NPF 机制有可能改善高污染地区的大气模拟。
Sulfur trioxide (SO3) is one of the most active chemical species in the atmosphere, and its atmospheric fate has profound implications to air quality and human health. The dominant gas-phase loss pathway for SO3 is generally believed to be the reaction with water molecules, resulting in sulfuric acid. The latter is viewed as a critical component in the new particle formation (NPF). Herein, a new and competitive loss pathway for SO3 in the presence of abundant gas-phase ammonia (NH3) species is identified. Specifically, the reaction between SO3 and NH3, which produces sulfamic acid, can be self-catalyzed by the reactant (NH3). In dry and heavily polluted areas with relatively high concentrations of NH3, the effective rate constant for the bimolecular SO3-NH3 reaction can be sufficiently fast through this new loss pathway for SO3 to become competitive with the conventional loss pathway for SO3 with water. Furthermore, this study shows that the final product of the reaction, namely, sulfamic acid, can enhance the fastest possible rate of NPF from sulfuric acid and dimethylamine (DMA) by about a factor of 2. An alternative source of stabilizer for acid-base clustering in the atmosphere is suggested, and this new mechanism for NPF has potential to improve atmospheric modeling in highly polluted regions.