Yields of oxidized volatile organic compounds during the OH radical initiated oxidation of isoprene, methyl vinyl ketone, and methacrolein under high–NO&lt;sub&gt;x&lt;/sub&gt; conditions

Abstract. We present first-generation and total production yields of glyoxal, methylglyoxal, glycolaldehyde, and hydroxyacetone from the oxidation of isoprene, methyl vinyl ketone (MVK), and methacrolein (MACR) with OH under high NOx conditions. Several of these first-generation yields are not included in commonly used chemical mechanisms, such as the Leeds Master Chemical Mechanism (MCM) v. 3.1. Inclusion of first-generation production of glyoxal, glycolaldehyde and hydroxyacetone from isoprene and methylglyoxal from MACR greatly improves performance of an MCM based model during the initial part of the experiments. In order to further improve performance of the MCM based model, higher generation glyoxal production was reduced by lowering the first-generation yield of glyoxal from C5 carbonyls. The results suggest that glyoxal production from reaction of OH with isoprene under high NOx conditions can be approximated by inclusion of a first-generation production term together with secondary production only via glycolaldehyde. Analogously, methylglyoxal production can be approximated by a first-generation production term from isoprene, and secondary production via MVK, MACR and hydroxyacetone. The first-generation yields reported here correspond to less than 5% of the total oxidized yield from isoprene and thus only have a small effect on the fate of isoprene. However, due to the abundance of isoprene, the combination of first-generation yields and reduced higher generation production of glyoxal from C5 carbonyls is important for models which include the production of the small organic molecules from isoprene.

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Yields of oxidized volatile organic compounds during the OH radical initiated oxidation of isoprene, methyl vinyl ketone, and methacrolein under high-NO<sub>x</sub> conditions

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-10779-2011 ◽

2011 ◽

Vol 11 (21) ◽

pp. 10779-10790 ◽

Cited By ~ 77

Author(s):

M. M. Galloway ◽

A. J. Huisman ◽

L. D. Yee ◽

A. W. H. Chan ◽

C. L. Loza ◽

...

Keyword(s):

Secondary Production ◽

First Generation ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Chemical Mechanism ◽

Total Production ◽

Production Term ◽

Methyl Vinyl ◽

Chemical Mechanisms ◽

Master Chemical Mechanism

Abstract. We present first-generation and total production yields of glyoxal, methylglyoxal, glycolaldehyde, and hydroxyacetone from the oxidation of isoprene, methyl vinyl ketone (MVK), and methacrolein (MACR) with OH under high NOx conditions. Several of these first-generation yields are not included in commonly used chemical mechanisms, such as the Leeds Master Chemical Mechanism (MCM) v. 3.2. The first-generation yield of glyoxal from isoprene was determined to be 2.1 (±0.6)%. Inclusion of first-generation production of glyoxal, glycolaldehyde and hydroxyacetone from isoprene greatly improves performance of an MCM based model during the initial part of the experiments. In order to further improve performance of the MCM based model, higher generation glyoxal production was reduced by lowering the first-generation yield of glyoxal from C5 hydroxycarbonyls. The results suggest that glyoxal production from reaction of OH with isoprene under high NOx conditions can be approximated by inclusion of a first-generation production term together with secondary production only via glycolaldehyde. Analogously, methylglyoxal production can be approximated by a first-generation production term from isoprene, and secondary production via MVK, MACR and hydroxyacetone. The first-generation yields reported here correspond to less than 5% of the total oxidized yield from isoprene and thus only have a small effect on the fate of isoprene. However, due to the abundance of isoprene, the combination of first-generation yields and reduced higher generation production of glyoxal from C5 hydroxycarbonyls is important for models that include the production of the small organic molecules from isoprene.

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Radical mechanisms of methyl vinyl ketone oligomerization through aqueous phase OH-oxidation: on the paradoxical role of dissolved molecular oxygen

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-6473-2013 ◽

2013 ◽

Vol 13 (13) ◽

pp. 6473-6491 ◽

Cited By ~ 35

Author(s):

P. Renard ◽

F. Siekmann ◽

A. Gandolfo ◽

J. Socorro ◽

G. Salque ◽

...

Keyword(s):

Aqueous Phase ◽

High Resolution Mass Spectrometry ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Chemical Mechanism ◽

Radical Oxidation ◽

Methyl Vinyl ◽

Chemical Mechanisms ◽

Phase Chemistry

Abstract. It is now accepted that one of the important pathways of secondary organic aerosol (SOA) formation occurs through aqueous phase chemistry in the atmosphere. However, the chemical mechanisms leading to macromolecules are still not well understood. It was recently shown that oligomer production by OH radical oxidation in the aerosol aqueous phase from α-dicarbonyl precursors, such as methylglyoxal and glyoxal, is irreversible and fast. Methyl vinyl ketone (MVK) was chosen in the present study as it is an α,β-unsaturated carbonyl that can undergo radical oligomerization in the aerosol aqueous phase. We present here experiments on the aqueous phase OH-oxidation of MVK, performed under various conditions. Using NMR and UV absorption spectroscopy, high and ultra-high resolution mass spectrometry, we show that the fast formation of oligomers up to 1800 Da is due to radical oligomerization of MVK, and 13 series of oligomers (out of a total of 26 series) are identified. The influence of atmospherically relevant parameters such as temperature, initial concentrations of MVK and dissolved oxygen are presented and discussed. In agreement with the experimental observations, we propose a chemical mechanism of OH-oxidation of MVK in the aqueous phase that proceeds via radical oligomerization of MVK on the olefin part of the molecule. This mechanism highlights in our experiments the paradoxical role of dissolved O2: while it inhibits oligomerization reactions, it contributes to produce oligomerization initiator radicals, which rapidly consume O2, thus leading to the dominance of oligomerization reactions after several minutes of reaction. These processes, together with the large range of initial concentrations investigated show the fundamental role that radical oligomerization processes likely play in polluted fogs and atmospheric aerosol.

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Radical mechanisms of methyl vinyl ketone oligomerization through aqueous phase OH-oxidation: on the paradoxical role of dissolved molecular oxygen

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-2913-2013 ◽

2013 ◽

Vol 13 (1) ◽

pp. 2913-2954 ◽

Cited By ~ 2

Author(s):

P. Renard ◽

F. Siekmann ◽

A. Gandolfo ◽

J. Socorro ◽

G. Salque ◽

...

Keyword(s):

Aqueous Phase ◽

High Resolution Mass Spectrometry ◽

Organic Aerosol ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Chemical Mechanism ◽

Methyl Vinyl ◽

Phase Chemistry ◽

Dissolved O2

Abstract. It is now accepted that one of the important pathways of Secondary Organic Aerosol (SOA) formation occurs through aqueous phase chemistry in the atmosphere. However, the liquid phase chemical mechanisms leading to macromolecules are still not well understood. For α-dicarbonyl precursors, such as methylglyoxal and glyoxal, radical reactions through OH-oxidation produce oligomers, irreversibly and faster than accretion reactions. Methyl vinyl ketone (MVK) was chosen in the present study as it is an α, β-unsaturated carbonyl that can undergo such reaction pathways in the aqueous phase and forms even high molecular weight oligomers. We present here experiments on the aqueous phase OH-oxidation of MVK, performed under atmospheric relevant conditions. Using NMR and UV absorption spectroscopy, high and ultra-high resolution mass spectrometry, we show that the fast formation of oligomers up to 1800 Da is due to radical oligomerization of MVK, and 13 series of oligomers (out of a total of 26 series) are identified. The influence of atmospherically relevant parameters such as temperature, initial concentrations of MVK and dissolved oxygen are presented and discussed. In agreement with the experimental observations, we propose a chemical mechanism of OH-oxidation of MVK in the aqueous phase that proceeds via radical oligomerization of MVK on the olefin part of the molecule. This mechanism highlights the paradoxical role of dissolved O2: while it inhibits oligomerization reactions, it contributes to produce oligomerization initiator radicals, which rapidly consume O2, thus leading to the supremacy of oligomerization reactions after several minutes of reaction. These processes, together with the large ranges of initial concentrations investigated (60–656 μM of dissolved O2 and 0.2–20 mM of MVK) show the fundamental role that O2 likely plays in atmospheric organic aerosol.

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Laboratory simulation for the aqueous OH-oxidation of methyl vinyl ketone and methacrolein: significance to the in-cloud SOA production

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-9551-2010 ◽

2010 ◽

Vol 10 (19) ◽

pp. 9551-9561 ◽

Cited By ~ 53

Author(s):

X. Zhang ◽

Z. M. Chen ◽

Y. Zhao

Keyword(s):

Molecular Weight ◽

Oxalic Acid ◽

First Generation ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Laboratory Simulation ◽

Small Molecular Weight ◽

Kinetics Parameters ◽

Methyl Vinyl ◽

Radical Processes

Abstract. Increasing evidence suggests that secondary organic aerosol (SOA) is formed through aqueous phase reactions in atmospheric clouds. In the present study, the aqueous oxidation of methyl vinyl ketone (MVK) and methacrolein (MACR) via OH radical were investigated, with an emphasis on the composition and variation of small-molecular-weight organic products. In addition, high-molecular-weight compounds (HMWs) were found, interpreted as the ion abundance and time evolution. Our results provide, for the first time to our knowledge, experimental evidence that aqueous OH-oxidation of MVK contributes to SOA formation. Further, a mechanism primarily involving radical processes was proposed to gain a basic understanding of these two reactions. Based on the assumed mechanism, a kinetic model was developed for comparison with the experimental results. The model reproduced the observed profiles of first-generation intermediates, but failed to simulate the kinetics of most organic acids mainly due to the lack of chemical kinetics parameters for HMWs. A sensitivity analysis was performed in terms of the effect of stoichiometric coefficients for precursors on oxalic acid yields and the result indicates that additional pathways involving HMWs chemistry might play an important role in the formation of oxalic acid. We suggest that further study is needed for better understanding the behavior of multi-functional products and their contribution to the oxalic acid formation.

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Aqueous-phase oligomerization of methyl vinyl ketone through photooxidation – Part 2: Development of the chemical mechanism and atmospheric implications

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-9109-2015 ◽

2015 ◽

Vol 15 (16) ◽

pp. 9109-9127 ◽

Cited By ~ 13

Author(s):

B. Ervens ◽

P. Renard ◽

S. Tlili ◽

S. Ravier ◽

J.-L. Clément ◽

...

Keyword(s):

Aqueous Phase ◽

Laboratory Experiments ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Box Model ◽

Chemical Mechanism ◽

Oxygen Solubility ◽

Methyl Vinyl ◽

Oligomer Formation ◽

Wide Range

Abstract. Laboratory experiments of efficient oligomerization from methyl vinyl ketone (MVK) in the bulk aqueous phase were simulated in a box model. Kinetic data are applied (if known) or fitted to the observed MVK decay and oligomer mass increase. Upon model sensitivity studies, in which unconstrained rate constants were varied over several orders of magnitude, a set of reaction parameters was found that could reproduce laboratory data over a wide range of experimental conditions. This mechanism is the first that comprehensively describes such radical-initiated oligomer formation. This mechanism was implemented into a multiphase box model that simulates secondary organic aerosol (SOA) formation from isoprene, as a precursor of MVK and methacrolein (MACR) in the aqueous and gas phases. While in laboratory experiments oxygen limitation might occur and lead to accelerated oligomer formation, such conditions are likely not met in the atmosphere. The comparison of predicted oligomer formation shows that MVK and MACR likely do negligibly contribute to total SOA as their solubilities are low and even reduced in aerosol water due to ionic strength effects (Setchenov coefficients). Significant contribution by oligomers to total SOA might only occur if a substantial fraction of particulate carbon acts as oligomer precursors and/or if oxygen solubility in aerosol water is strongly reduced due to salting-out effects.

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Laboratory simulation for the aqueous OH-oxidation of methyl vinyl ketone and methacrolein: significance to the in-cloud SOA production

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-15595-2010 ◽

2010 ◽

Vol 10 (6) ◽

pp. 15595-15628

Author(s):

X. Zhang ◽

Z. M. Chen ◽

Y. Zhao

Keyword(s):

Oxalic Acid ◽

First Generation ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Laboratory Simulation ◽

Cloud Droplets ◽

Kinetics Parameters ◽

Methyl Vinyl ◽

Oh Reactions ◽

Radical Processes

Abstract. Increasing evidence suggests that secondary organic aerosol (SOA) is formed through aqueous phase reactions in atmospheric clouds. In the present study, the aqueous oxidation of methyl vinyl ketone (MVK) and methacrolein (MACR) via OH radical were investigated under conditions typical of cloud droplets, with an emphasis on the composition and variation of oxygenated organic products. In addition to the small products, high-molecular-weight compounds (HMCs) with an oligomer system was found, interpreted as the ion abundance and time evolution. We observed the SOA yields of 23.8% and 8.8% from MVK–OH and MACR–OH reactions, respectively, for the entire 7 h experiment. Our results provide, for the first time to our knowledge, experimental evidence that aqueous OH-oxidation of MVK contributes to SOA formation. Further, a mechanism primarily involving radical processes was proposed to gain a basic understanding of these two reactions. Based on the assumed mechanism, a specific box model was developed for comparison with the experimental results. The model reproduced the observed profiles of first-generation intermediates, but failed to simulate the kinetics of most organic acids mainly due to the lack of chemical kinetics parameters for HMCs. A sensitivity analysis was performed in terms of the effect of reaction branching ratios on oxalic acid yields and the result indicates that additional pathways involving HMCs chemistry might play an important role in the formation of oxalic acid. We suggest that corresponding experiments are needed for better understanding the behavior of multi-functional products and their contribution to the oxalic acid formation.

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Technical note: Conversion of isoprene hydroxy hydroperoxides (ISOPOOHs) on metal environmental simulation chamber walls

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-4053-2017 ◽

2017 ◽

Vol 17 (6) ◽

pp. 4053-4062 ◽

Cited By ~ 4

Author(s):

Anne-Kathrin Bernhammer ◽

Martin Breitenlechner ◽

Frank N. Keutsch ◽

Armin Hansel

Keyword(s):

Gas Phase ◽

Technical Note ◽

Vinyl Ketone ◽

Heterogeneous Reactions ◽

Methyl Vinyl Ketone ◽

Oxidation Products ◽

Chemical Mechanism ◽

Stainless Steel Surface ◽

Methyl Vinyl

Abstract. Sources and sinks of isoprene oxidation products from low-NOx isoprene chemistry have been studied at the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber with a custom-built selective reagent ion time-of-flight mass spectrometer (SRI-ToF-MS), which allows quantitative measurement of isoprene hydroxy hydroperoxides (ISOPOOHs). The measured concentrations of the main oxidation products were compared to chemical box model simulations based on the Leeds Master Chemical Mechanism (MCM) v3.3. The modeled ISOPOOH concentrations are a factor of 20 higher than the observed concentrations, and methyl vinyl ketone (MVK) and methacrolein (MACR) concentrations are up to a factor of 2 lower compared to observations, despite the artifact-free detection method. Addition of catalytic conversion of 1,2-ISOPOOH and 4,3-ISOPOOH to methyl vinyl ketone (MVK) and methacrolein (MACR) on the stainless-steel surface of the chamber to the chemical mechanism resolves the discrepancy between model predictions and observation. This suggests that isoprene chemistry in a metal chamber under low-NOx conditions cannot be described by a pure gas phase model alone. Biases in the measurement of ISOPOOH, MVK, and MACR can be caused not only intra-instrumentally but also by the general experimental setup. The work described here extends the role of heterogeneous reactions affecting gas phase composition and properties from instrumental surfaces, described previously, to general experimental setups. The role of such conversion reactions on real environmental surfaces is yet to be explored.

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Aqueous phase oligomerization of methyl vinyl ketone through photooxidation – Part 2: Development of the chemical mechanism and atmospheric implications

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-21565-2014 ◽

2014 ◽

Vol 14 (15) ◽

pp. 21565-21609 ◽

Cited By ~ 3

Author(s):

B. Ervens ◽

P. Renard ◽

S. Ravier ◽

J.-L. Clément ◽

A. Monod

Keyword(s):

Gas Phase ◽

Aqueous Phase ◽

Formation Rate ◽

Liquid Water Content ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Chemical Mechanism ◽

Atmospheric Conditions ◽

Methyl Vinyl ◽

Oligomer Formation

Abstract. We developed a chemical mechanism based on laboratory experiments that have shown efficient oligomerization from methyl vinyl ketone (MVK) in the bulk aqueous phase. Kinetic data are applied (if known) or fitted to the observed MVK decay and oligomer mass increase. The mechanism is then implemented into a multiphase box model that simulates (i) oligomer formation upon uptake of MVK from the gas phase, and (ii) SOA formation from isoprene, as a precursor of MVK and methacrolein (MACR) in the aqueous and gas phases. Model results show that under atmospheric conditions, the oligomer formation rate strongly depends on the availability of dissolved oxygen. If oxygen is consumed too quickly or its solubility is kinetically or thermodynamically limited, oligomerization is accelerated, in agreement with the laboratory studies. The comparison of predicted oligomer formation shows that for most model assumptions (e.g. depending on the assumed partitioning of MVK and MACR), SOA formation from isoprene in the gas phase exceeds aqueous SOA formation by a factor 3–4. However, at high aerosol liquid water content and potentially high partitioning of oligomer precursors into the aqueous phase, SOA formation in both phases might be equally efficient.

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