Role of Carbonaceous Aerosols in Catalyzing Sulfate Formation
Role of Carbonaceous Aerosols in Catalyzing Sulfate Formation
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碳质气溶胶在催化硫酸盐形成中的作用
DOI：
10.1021/acscatal.7b04195
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发表时间：
2018-05-01
期刊：
影响因子：
12.9
通讯作者：
He, Hong
中科院分区：
文献类型：
--
作者：
He, Guangzhi;Ma, Jinzhu;He, Hong
硫酸盐的持续快速形成是推动细颗粒物爆发式增长、加剧中国严重雾霾发展的首要因素。然而，硫酸盐持续生产的潜在机制仍然高度不确定。在这里，我们证明了烟灰不仅是颗粒物的主要成分，而且是一种天然的碳催化剂，可以在环境条件下激活分子O-2并催化SO2氧化成硫酸盐。此外，高相对湿度，通常发生在严重的雾霾事件中，可以通过降低反应障碍大大加速催化循环，从而更快地生成硫酸盐。碳质烟尘气溶胶催化硫酸盐的生成途径以无处不在的O-2作为最终氧化剂，可以在光化学还原的夜间进行。雾霾期间较高的相对湿度可以进一步促进烟尘催化硫酸盐生成过程。因此，本研究揭示了开放大气中，特别是在以高浓度SO2和颗粒碳为特征的高污染条件下，持续形成硫酸盐雾霾的缺失和广泛来源，有助于制定更有效的政策来减轻和控制雾霾污染。
The persistent and fast formation of sulfate is a primary factor driving the explosive growth of fine particles and exacerbating China's severe haze development. However, the underlying mechanism for the persistent production of sulfate remains highly uncertain. Here, we demonstrate that soot is not only a major component of the particulate matter but also a natural carbocatalyst to activate molecular O-2 and catalyze the oxidation of SO2 to sulfate under ambient conditions. Moreover, high relative humidity, typically occurring in severe haze events, can greatly accelerate the catalytic cycle by reducing the reaction barriers, leading to faster sulfate production. The formation pathway of sulfate catalyzed by carbonaceous soot aerosols uses the ubiquitous O-2 as the ultimate oxidant and can proceed at night when photochemistry is reduced. The high relative humidity during haze episodes can further promote the soot-catalyzed sulfate-producing process. Therefore, this study reveals a missing and widespread source for the persistent sulfate haze formation in the open atmosphere, particularly under highly polluted conditions characterized by high concentrations of both SO2 and particulate carbon, and is helpful to the development of more efficient policies to mitigate and control haze pollution.