title: The effects of acetaldehyde, glyoxal and acetic acid on the heterogeneous reaction of nitrogen dioxide on gamma-alumina.
abstract: Heterogeneous reactions of nitrogen oxides on the surface of aluminium oxide result in the formation of adsorbed nitrite and nitrate. However, little is known about the effects of other species on these heterogeneous reactions and their products. In this study, diffuse reflectance infrared spectroscopy (DRIFTS) was used to analyze the process of the heterogeneous reaction of NO2 on the surface of aluminium oxide particles in the presence of pre-adsorbed organic species (acetaldehyde, glyoxal and acetic acid) at 298 K and reveal the influence of these organic species on the formation of adsorbed nitrite and nitrate. It was found that the pre-adsorption of organic species (acetaldehyde, glyoxal and acetic acid) on γ-Al2O3 could suppress the formation of nitrate to different extents. Under the same experimental conditions, the suppression of the formation of nitrate by the pre-adsorption of acetic acid is much stronger than that by pre-adsorption of acetaldehyde and glyoxal, indicating that the influence of acetic acid on the heterogeneous reaction of NO2 is different from that of acetaldehyde and glyoxal. Surface nitrite is formed and identified to be an intermediate product. For the heterogeneous reaction of NO2 on the surface of γ-Al2O3 with and without the pre-adsorption of acetaldehyde and glyoxal, it is firstly formed and then gradually disappears as the reaction proceeds, but for the reaction with the pre-adsorption of acetic acid, it is the final main product besides nitrate. This indicates that the pre-adsorption of acetic acid would promote the formation of nitrite, while the others would not change the trend of the formation of nitrite. The possible influence mechanisms of the pre-adsorption of acetaldehyde, glyoxal and acetic acid on the heterogeneous conversion of NO2 on γ-Al2O3 are proposed and atmospheric implications based on these results are discussed.
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution, Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, China. ldkong@fudan.edu.cn.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Sun
authors.forename: Lingdong
authors.initials: L
authors.lastname: Kong
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Ding
authors.forename: Chengtian
authors.initials: C
authors.lastname: Du
authors.forename: Xi
authors.initials: X
authors.lastname: Zhao
authors.forename: Jianmin
authors.initials: J
authors.lastname: Chen
authors.forename: Hongbo
authors.initials: H
authors.lastname: Fu
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.forename: Tiantao
authors.initials: T
authors.lastname: Cheng