黑碳活化O2及催化氧化SO2生成硫酸盐二次粒子作用机理研究

Sulfate is recognized as the primary factor driving haze formation. Identification of the missing production mechanism of sulfate during air pollution episodes is the key to explaining severe haze formation. The heterogeneous oxidation of SO2 on soot particles may play an important role in the explosive growth of sulfate and the rapid development of heavy haze pollution. In this project, we will apply the combination of quantum chemical calculation, molecular dynamics simulation and spectroscopy to investigate the mechanism of the activation of O2 and the catalytic oxidation of SO2 to secondary sulfate by soot. We will also explore the synergistic effect between NO2 and SO2 and the role of relative humidity in the heterogeneous oxidation of SO2 on soot surfaces at the atomic-molecular level. Based on the computational and experimental analysis, we will identify the active sites on soot surfaces for O2 activation, illustrate the relationship between the structure of active sites and their activity, and determine the key factors for the catalytic oxidation of SO2 to secondary sulfate by soot. The results will help us to better understand the underlying mechanism of severe haze formation, and provide scientific guide for pollution control.

硫酸盐是灰霾天气形成的主要驱动物种，揭示硫酸盐在重污染天气未知的主导生成机制是解释重霾形成的关键所在。SO2在黑碳颗粒物表面的非均相氧化过程对硫酸盐的爆发式增长和重霾污染天气的快速发展具有尚未被清楚认知的重要作用。针对此科学问题，本项目将应用量子化学计算、分子动力学模拟结合分子光谱等实验方法，从分子/原子水平研究黑碳活化O2分子、催化氧化SO2转化生成硫酸盐的非均相反应机理，并考察NO2气体共存的协同氧化作用和大气湿度对反应影响的机制。阐明黑碳颗粒物表面活化O2分子的活性位点，揭示活性位点的结构类型与其非均相活性间的构效关系，明确影响黑碳颗粒物催化SO2向硫酸盐转化的关键因子和作用机理，为解释重霾天气成因和科学控制提供理论指导。

大气复合污染造成细颗粒物（PM2.5）浓度上升，其主要原因在于二次污染物的爆发增长。硫酸盐是PM2.5的主要组分之一。现有已知的大气化学机制无法完全解释大气颗粒物中的硫酸盐含量，特别是我国重霾期间硫酸盐快速增长的现象。本项目应用理论计算与实验技术相结合，从原子水平研究了黑碳活化O2分子、催化氧化SO2转化生成硫酸盐的非均相反应机理。研究揭示了黑碳表面活化O2分子的活性位点，明确了影响黑碳颗粒物催化SO2向硫酸盐转化的关键因子和作用机理。共发表SCI论文7篇，其中Environmental Science & Technology论文4篇，ACS Catalysis论文2篇。本项目阐明了黑碳对硫酸盐生成的催化机制，揭示了重霾天气硫酸盐爆发增长的一个重要未知源。