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.

Role of NH3 in the Heterogeneous Formation of Secondary Inorganic Aerosols on Mineral Oxides

“…In the present study, the bands at 1563 (ν 3,high ) and 1259 cm –1 (ν 3,low ) were assigned to bidentate nitrates, and the band at 1288 cm –1 (ν 3, low ) was assigned to monodentate nitrate with no observation of its higher wavenumber band due to low coverage. ,− The weak adsorption band at 1006 cm –1 (ν 1 ) was assigned to nitrate species, possibly in the bidentate state . With exposure time increasing, solvated nitrate species were observed at 1417, 1379, and 1347 cm –1 . ,, In addition, a small amount of bridging nitro–nitrito and bridging monodentate nitrito products were also detected, as indicated by the presence of the bands at 1155 cm –1 (ν 3 ) and 1092 cm –1 (ν 1 ), respectively. , The obvious consumption of hydroxyl groups (OH) at the bands of 3689 and 3667 cm –1 indicated that the formation of nitrate/nitrito species was due to the interaction of NO 2 with those OH sites, accompanied by the production of water molecules with the stretching adsorption mode and bending adsorption mode at the 3567 and 1632 cm –1 bands …”

“…43 With exposure time increasing, solvated nitrate species were observed at 1417, 1379, and 1347 cm −1 . 19,44,45 In addition, a small amount of bridging nitro−nitrito and bridging monodentate nitrito products were also detected, as indicated by the presence of the bands at 1155 cm −1 (ν 3 ) and 1092 cm −1 (ν 1 ), respectively. 38,42 The obvious consumption of hydroxyl groups (OH) at the bands of 3689 and 3667 cm −1 indicated that the formation of nitrate/nitrito species was due to the interaction of NO 2 with those OH sites, accompanied by the production of water molecules with the stretching adsorption mode and bending adsorption mode at the 3567 and 1632 cm −1 bands.…”

The Importance of Cannizzaro-Type Reactions during Electrocatalytic Reduction of Carbon Dioxide

“…The fact that no aldol reaction products are detected suggests that the presence of the electrode surface plays a role. Even though the classical Cannizzaro and aldol reactions were originally reported for homogeneous alkaline solutions, a variety of heterogeneous and catalytic systems for these reactions have been investigated for formaldehyde − and acetaldehyde − as well. Several groups have reported that surface OH – can initiate Cannizzaro disproportionation of surface adsorbed HCHO leading to formate ions and methoxy groups. − A mechanism including a nucleophilic-addition transformation of HCHO to dioxymethylene (CH 2 O 2 ) which subsequently reacts with a HCHO molecule to form formate and methoxy groups has been proposed …”

Heterogeneous Reactions of Acetic Acid with Oxide Surfaces: Effects of Mineralogy and Relative Humidity

“…Another DRIFTS study suggested that the heterogeneous reaction of CH 3 COOH­(g) with MgO, α-Al 2 O 3 , and CaCO 3 particles leads to the production of acetate, the formation of which is enhanced at higher RH for all the three different types of particles . A very recent study also shows that pretreatment of γ-Al 2 O 3 particles with CH 3 COOH­(g) could affect subsequent heterogeneous interactions with NO 2 …”

“…40 A very recent study also shows that pretreatment of γ-Al 2 O 3 particles with CH 3 COOH(g) could affect subsequent heterogeneous interactions with NO 2 . 41 In addition to the removal of acetic acid from the gas phase and modification of the particle composition, previous studies suggested that heterogeneous reaction with acetic acid could also lead to changes in hygroscopicity and cloud condensation nucleation (CCN) activity. For example, Ma et al 40 found that the water adsorption abilities of MgO, α-Al 2 O 3 , and CaCO 3 particles were significantly increased after reaction with CH 3 COOH(g).…”