scholarly journals An experimental study of the reactivity of terpinolene and β-caryophyllene with the nitrate radical

2021 ◽  
Author(s):  
Axel Fouqueau ◽  
Manuela Cirtog ◽  
Mathieu Cazaunau ◽  
Edouard Pangui ◽  
Jean-François Doussin ◽  
...  
Keyword(s):  
Gas Phase ◽  
Reaction Pathways ◽  
Main Reaction ◽  
Organic Nitrates ◽  
Nitrate Radical ◽  
Reaction Products ◽  
Radiative Balance ◽  
Chemical Mechanisms ◽  
Volatile Organic

Abstract. Biogenic volatile organic compounds (BVOCs) are subject to an intense emission by forests and crops into the atmosphere. They can rapidly react with the nitrate radical (NO3) during nighttime to form number of functionalized products. Among them, organic nitrates (ON) have been shown to behave as reservoirs of reactive nitrogen and consequently influence the ozone budget and secondary organic aerosols (SOA) which are known to have a direct and indirect effect on the radiative balance, and thus on climate. Nevertheless, BVOCs + NO3 reactions remain poorly understood. Thus, the primary purpose of the follow-up study is to furnish new kinetic and mechanistic data for one monoterpenes (C10H16), terpinolene, and one sesquiterpene (C15H24), β-caryophyllene, using simulation chamber experiments. These two compounds have been chosen in order to fill the lack of experimental data. Rate constants have been measured using both relative and absolute methods. They have been measured to be (5.5 ± 3.8) × 10−11 and (1.7 ± 1.4) × 10−11 cm3 molecule−1 s−1 for terpinolene and β-caryophyllene respectively. Mechanistic studies have also been conducted in order to identify and quantify the main reaction products. Total organic nitrates and SOA yields have been determined. Both terpenes appear to be major ON precursors both in gas and particle phase with formation yields of 69 % for terpinolene and 79 % for β-caryophyllene respectively. They also are major SOA precursor, with maximum SOA yields of around 60 % for both of the compounds. In order to support these observations, chemical analyses of the gas phase products were performed at the molecular scale using PTR-TOF-MS and FTIR. Detected products allowed proposing chemical mechanisms and providing explanations through peroxy and alkoxy reaction pathways.

scholarly journals A comparative and experimental study of the reactivity with nitrate radical of two terpenes: <i>α</i>-terpinene and <i>γ</i>-terpinene

2020 ◽  
Vol 20 (23) ◽  
pp. 15167-15189
Author(s):  
Axel Fouqueau ◽  
Manuela Cirtog ◽  
Mathieu Cazaunau ◽  
Edouard Pangui ◽  
Jean-François Doussin ◽  
...  
Keyword(s):  
Main Reaction ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Nitrate Radical ◽  
Reaction Products ◽  
Chemical Mechanisms ◽  
Chemical Structures ◽  
Aerosol Mass ◽  
Similar Chemical ◽  
Volatile Organic

Abstract. Biogenic volatile organic compounds (BVOCs) are intensely emitted by forests and crops into the atmosphere. During the night, they react very rapidly with the nitrate radical (NO3), leading to the formation of a variety of functionalized products including organic nitrates and to large amounts of secondary organic aerosols (SOAs). Organic nitrates (ONs) have been shown not only to play a key role in the transport of reactive nitrogen and consequently in the ozone budget but also to be important components of the total organic-aerosol mass, while SOAs are known to play a direct and indirect role in the climate. However, the reactivity of BVOCs with NO3 remains poorly studied. The aim of this work is to provide new kinetic and mechanistic data for two monoterpenes (C10H16), α- and γ-terpinene, through experiments in simulation chambers. These two compounds, which have very similar chemical structures, have been chosen in order not only to overcome the lack of experimental data but also to highlight the influence of the chemical structure on the reactivity. Rate constants have been measured using both relative and absolute methods. They were found to be (1.2±0.5)×10-10 and (2.9±1.1)×10-11 cm3 molecule−1 s−1 for α- and γ-terpinene respectively. Mechanistic studies have also been conducted in order to identify and quantify the main reaction products. Total organic nitrate and SOA yields have been determined. While organic nitrate formation yields appear to be similar, SOA yields exhibit large differences with γ-terpinene being a much more efficient precursor of aerosols. In order to provide explanations for this difference, chemical analysis of the gas-phase products was performed at the molecular scale. Detected products allowed for proposing chemical mechanisms and providing explanations through peroxy and alkoxy reaction pathways.

scholarly journals A comparative and experimental study of the reactivity with nitrate radical of two terpenes: α-terpinene and γ-terpinene

2020 ◽  
Author(s):  
Axel Fouqueau ◽  
Manuela Cirtog ◽  
Mathieu Cazaunau ◽  
Edouard Pangui ◽  
Jean-François Doussin ◽  
...  
Keyword(s):  
Organic Aerosol ◽  
Main Reaction ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Nitrate Radical ◽  
Reaction Products ◽  
Chemical Mechanisms ◽  
Chemical Structures ◽  
Similar Chemical ◽  
Volatile Organic

Abstract. Biogenic volatile organic compounds (BVOCs) are intensely emitted by forests and crops into the atmosphere. During the night, they react very rapidly with the nitrate radical (NO3), leading to the formation of a variety of functionalized products including organic nitrates and to large amounts of secondary organic aerosols (SOA). Organic nitrates (ONs) have been shown to play a key role in the transport of reactive nitrogen and consequently in the ozone budget, but also to be important components of the total organic aerosol while SOA are known to play a direct and indirect role on the climate. However, the reactivity of BVOCs with NO3 remains poorly studied. The aim of this work is to provide new kinetic and mechanistic data for two monoterpenes (C10H16), α- and γ-terpinene, through experiments in simulation chambers. These two compounds, which have very similar chemical structures, have been chosen in order to fill the lack of experimental data but also to highlight the influence of the chemical structure on the reactivity. Rate constants have been measured using both relative and absolute methods. They were found to be (1.2 ± 0.5) x 10-10 and (2.9 ± 1.1) x 10-11 cm3 molecule-1 s-1 for α- and γ-terpinene respectively. Mechanistic studies have also been conducted in order to identify and quantify the main reaction products. Total organic nitrate and SOA yields have been determined. While organic nitrate formation yields appear to be similar, SOA yields exhibit large differences with γ-terpinene being a much more efficient precursor of aerosols. In order to provide explanations for this difference, chemical analysis of the gas phase products were performed at the molecular scale. Detected products allowed proposing chemical mechanisms and providing explanations through peroxy and alkoxy reaction pathways.

scholarly journals Importance of biogenic volatile organic compounds to acyl peroxy nitrates (APN) production in the southeastern US during SOAS 2013

2019 ◽  
Vol 19 (3) ◽  
pp. 1867-1880 ◽  
Author(s):  
Shino Toma ◽  
Steve Bertman ◽  
Christopher Groff ◽  
Fulizi Xiong ◽  
Paul B. Shepson ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Gas Phase ◽  
Organic Compounds ◽  
Model Simulation ◽  
Statistical Correlation ◽  
Organic Nitrates ◽  
Biogenic Volatile Organic Compounds ◽  
The North ◽  
Southeastern Us ◽  
Volatile Organic

Abstract. Gas-phase atmospheric concentrations of peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN), and peroxymethacryloyl nitrate (MPAN) were measured on the ground using a gas chromatograph electron capture detector (GC-ECD) during the Southern Oxidants and Aerosols Study (SOAS) 2013 campaign (1 June to 15 July 2013) in Centreville, Alabama, in order to study biosphere–atmosphere interactions. Average levels of PAN, PPN, and MPAN were 169, 5, and 9 pptv, respectively, and the sum accounts for an average of 16 % of NOy during the daytime (10:00 to 16:00 local time). Higher concentrations were seen on average in air that came to the site from the urban NOx sources to the north. PAN levels were the lowest observed in ground measurements over the past two decades in the southeastern US. A multiple regression analysis indicates that biogenic volatile organic compounds (VOCs) account for 66 % of PAN formation during this study. Comparison of this value with a 0-D model simulation of peroxyacetyl radical production indicates that at least 50 % of PAN formation is due to isoprene oxidation. MPAN has a statistical correlation with isoprene hydroxynitrates (IN). Organic aerosol mass increases with gas-phase MPAN and IN concentrations, but the mass of organic nitrates in particles is largely unrelated to MPAN.

scholarly journals Terpenes and their oxidation products in the French Landes forest: insights from Vocus PTR-TOF measurements

2020 ◽  
Vol 20 (4) ◽  
pp. 1941-1959 ◽  
Author(s):  
Haiyan Li ◽  
Matthieu Riva ◽  
Pekka Rantala ◽  
Liine Heikkinen ◽  
Kaspar Daellenbach ◽  
...  
Keyword(s):  
Gas Phase ◽  
Detection Efficiency ◽  
Ambient Air ◽  
Reaction Rates ◽  
Early Morning ◽  
Oxidation Products ◽  
Atmospheric Oxidation ◽  
Organic Nitrates ◽  
Reaction Products ◽  
Wide Range

Abstract. The capabilities of the recently developed Vocus proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF) are reported for the first time based on ambient measurements. With the deployment of the Vocus PTR-TOF, we present an overview of the observed gas-phase (oxygenated) molecules in the French Landes forest during summertime 2018 and gain insights into the atmospheric oxidation of terpenes, which are emitted in large quantities in the atmosphere and play important roles in secondary organic aerosol production. Due to the greatly improved detection efficiency compared to conventional PTR instruments, the Vocus PTR-TOF identifies a large number of gas-phase signals with elemental composition categories including CH, CHO, CHN, CHS, CHON, CHOS, and others. Multiple hydrocarbons are detected, with carbon numbers up to 20. Particularly, we report the first direct observations of low-volatility diterpenes in the ambient air. The diurnal cycle of diterpenes is similar to that of monoterpenes and sesquiterpenes but contrary to that of isoprene. Various types of terpene reaction products and intermediates are also characterized. Generally, the more oxidized products from terpene oxidations show a broad peak in the day due to the strong photochemical effects, while the less oxygenated products peak in the early morning and/or in the evening. To evaluate the importance of different formation pathways in terpene chemistry, the reaction rates of terpenes with main oxidants (i.e., hydroxyl radical, OH; ozone, O3; and nitrate radical, NO3) are calculated. For the less oxidized non-nitrate monoterpene oxidation products, their morning and evening peaks have contributions from both O3- and OH-initiated monoterpene oxidation. For the monoterpene-derived organic nitrates, oxidations by O3, OH, and NO3 radicals all contribute to their formation, with their relative roles varying considerably over the course of the day. Through a detailed analysis of terpene chemistry, this study demonstrates the capability of the Vocus PTR-TOF in the detection of a wide range of oxidized reaction products in ambient and remote conditions, which highlights its importance in investigating atmospheric oxidation processes.

scholarly journals Low-temperature electrocatalytic conversion of CO2 to liquid fuels: effect of the Cu particle size

2018 ◽  
Author(s):  
Antonio De Lucas-Consuegra ◽  
Juan Carlos Serrano-Ruiz ◽  
Nuria Gutierrez-Guerra ◽  
José Luis Valverde
Keyword(s):  
Particle Size ◽  
Low Temperature ◽  
Gas Phase ◽  
Electrocatalytic Activity ◽  
Water Electrolysis ◽  
Proton Exchange ◽  
Liquid Fuels ◽  
Main Reaction ◽  
Membrane Electrode ◽  
Reaction Products

A novel gas-phase electrocatalytic system based on a low-temperature proton exchange membrane (Sterion) was developed for the gas phase electrocatalytic conversion of CO2 to liquid fuels. This system achieved gas-phase electrocatalytic reduction of CO2 at low temperatures (below 90 ºC) over a Cu cathode by using water electrolysis-derived protons generated in-situ on an IrO2 anode. Three Cu-based cathodes with varying metal particle sizes were prepared by supporting this metal on an activated carbon at three loadings (50, 20, and 10 wt%; 50%Cu-AC, 20%Cu-AC, and 10%Cu-AC, respectively). The cathodes were characterized by N2 adsorption–desorption, temperature-programmed reduction (TPR), and X-ray diffraction (XRD) whereas their performance towards the electrocatalytic conversion of CO2 was subsequently studied. The membrane electrode assembly (MEA) containing the cathode with the largest Cu particle size (50%Cu-AC, 40 nm) showed the highest CO2 electrocatalytic activity per mole of Cu, with methyl formate being the main product. This higher electrocatalytic activity was attributed to the lower Cu–CO bonding strength over large Cu particles. Different product distributions were obtained over 20%Cu-AC and 10%Cu-AC, with acetaldehyde and methanol being the main reaction products, respectively. The CO2 consumption rate increased with the applied current and the reaction temperature.

Hydrogenolysis of Glycerol in Gas Phase on Cu-Cr Mixed Oxide Catalyst Doped with Ni

2017 ◽  
Vol 68 (5) ◽  
pp. 1118-1121
Author(s):  
Vasile Georgescu ◽  
Casen Panaitescu ◽  
Mihaela Bombos ◽  
Dorin Bombos
Keyword(s):  
Gas Phase ◽  
Propylene Glycol ◽  
Mixed Oxide ◽  
Oxide Catalyst ◽  
Molar Ratio ◽  
Main Reaction ◽  
Reaction Products ◽  
Glycerol Conversion ◽  
Mixed Oxide Catalyst ◽  
Temperature And Pressure

Hydrogenolysis of glycerol was conducted on catalyst of the type mixed oxide of Cu-Cr doped with NiO on g-Al2O3. The prepared catalyst was analyzed by XRD, IR and TPR. Catalytic tests were carried out on a laboratory plant in continuous flow system on a reactor equipped with heating mantle, at molar ratio of glycerol / hydrogen of 1/300, glycerol volume hourly space velocities 1000s-1, temperatures 200-220oC and pressures 3-5 bar. The main reaction products identified were propylene glycol and hydroxyacetone. Glycerol conversion increases with temperature and pressure on ranges of parameters studied. Selectivity to propylene glycol increases with increasing of temperature and pressure and the selectivity to hydroxyacetone decreases with increasing of temperature and pressure on the variation range of the parameters studied.

scholarly journals Low-Temperature Electrocatalytic Conversion of CO2 to Liquid Fuels: Effect of the Cu Particle Size

Catalysts ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 340 ◽  
Author(s):  
Antonio de Lucas-Consuegra ◽  
Juan Serrano-Ruiz ◽  
Nuria Gutiérrez-Guerra ◽  
José Valverde
Keyword(s):  
Particle Size ◽  
Low Temperature ◽  
Gas Phase ◽  
Electrocatalytic Activity ◽  
Water Electrolysis ◽  
Proton Exchange ◽  
Liquid Fuels ◽  
Main Reaction ◽  
Membrane Electrode ◽  
Reaction Products

A novel gas-phase electrocatalytic system based on a low-temperature proton exchange membrane (Sterion) was developed for the gas-phase electrocatalytic conversion of CO2 to liquid fuels. This system achieved gas-phase electrocatalytic reduction of CO2 at low temperatures (below 90 °C) over a Cu cathode by using water electrolysis-derived protons generated in-situ on an IrO2 anode. Three Cu-based cathodes with varying metal particle sizes were prepared by supporting this metal on an activated carbon at three loadings (50, 20, and 10 wt %; 50% Cu-AC, 20% Cu-AC, and 10% Cu-AC, respectively). The cathodes were characterized by N2 adsorption–desorption, temperature-programmed reduction (TPR), and X-ray diffraction (XRD) and their performance towards the electrocatalytic conversion of CO2 was subsequently studied. The membrane electrode assembly (MEA) containing the cathode with the largest Cu particle size (50% Cu-AC, 40 nm) showed the highest CO2 electrocatalytic activity per mole of Cu, with methyl formate being the main product. This higher electrocatalytic activity was attributed to the lower Cu–CO bonding strength over large Cu particles. Different product distributions were obtained over 20% Cu-AC and 10% Cu-AC, with acetaldehyde and methanol being the main reaction products, respectively. The CO2 consumption rate increased with the applied current and reaction temperature.

Optical Properties of Secondary Organic Aerosol from Nitrate Radical Oxidation of Biogenic Volatile Organic Compounds: The Role of Highly Oxygenated Organic Nitrates  

2020 ◽  
Author(s):  
Yinon Rudich ◽  
Quanfu He ◽  
Alexander Laskin ◽  
Steve Brown
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
High Resolution ◽  
Organic Compounds ◽  
Atmospheric Chemistry ◽  
Organic Nitrates ◽  
Nitrate Radical ◽  
Biogenic Volatile Organic Compounds ◽  
Radical Oxidation ◽  
Volatile Organic

&lt;p&gt;Nitrate radical (NO&lt;sub&gt;3&lt;/sub&gt;) oxidation of biogenic volatile organic compounds (BVOCs) represents one of the most important interactions between anthropogenic emissions related to combustion and natural emissions from the biosphere. The functionalization process during this oxidation process leads to the formation of multifunctional compounds such as organic nitrates (ON). ON account for a significant fraction of total organic aerosols (OA) in ambient air, which influence atmospheric chemistry process, air quality, and climate through regional and global budgets for reactive nitrogen (particularly ON), ozone, and OA formation. Despite the significance of this process in atmospheric chemistry, the climatic effect of SOA from this process is undefined, largely due to a lack of knowledge about their optical properties with respect to their chemical composition. In this study, we generated SOA from NO&lt;sub&gt;3&lt;/sub&gt; radical oxidation of a series BVOCs including isoprene, monoterpenes, and sesquiterpenes followed by photo-chemically aging in oxidation flow reactor (OFR/PAM). The chemical composition of the SOA was characterized online by high-resolution time-of-flight mass spectrometer (HR-Tof-AMS) and off-line by ultra-high-performance liquid chromatography (HPLC) coupled with photodiode array (PDA) detector coupled to a high-resolution Orbitrap mass spectrometer with a standard electrospray ionization (ESI) source (HPLC-PDA-HRMS). The UV-visible wavelength-resolved refractive index of the SOA, which is essential to understand their radiative forcing, was retrieved by measuring the light extinction using a novel broadband cavity-enhanced spectrometer (BBCES, 315-700 nm). We found that the SOA contain a large fraction of highly oxygenated ON, consisting of monomers and oligomers with single and multiple nitrate groups, which formed through bimolecular and unimolecular reactions. Strong absorption was detected in the UVA range which was attributed to the ON. The influence of the initial BVOCs/NO&lt;sub&gt;3&lt;/sub&gt; ratio and the transition from nighttime oxidation to daytime aging on the SOA optical properties will be discussed. We will highlight the link between the SOA optical properties evolution and the chemical composition transformation with respect to the highly oxygenated ON formation and its atmospheric fate upon daytime photochemical aging.&lt;/p&gt;

scholarly journals Terpenes and their oxidation products in the French Landes forest: insight from Vocus PTR-TOF measurements

2019 ◽  
Author(s):  
Haiyan Li ◽  
Matthieu Riva ◽  
Pekka Rantala ◽  
Liine Heikkinen ◽  
Kaspar Daellenbach ◽  
...  
Keyword(s):  
Gas Phase ◽  
Detection Efficiency ◽  
Ambient Air ◽  
Reaction Rates ◽  
Early Morning ◽  
Oxidation Products ◽  
Atmospheric Oxidation ◽  
Organic Nitrates ◽  
Reaction Products ◽  
Wide Range

Abstract. The capabilities of the recently developed Vocus proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF) are reported for the first time based on ambient measurements. With the deployment of the Vocus PTR-TOF, we present an overview of the observed gas-phase (oxygenated) molecules in the French Landes forest during summertime 2018 and gain insights into the atmospheric oxidation of terpenes, which are emitted in large quantities in the atmosphere and play important roles in secondary organic aerosol production. Due to the greatly improved detection efficiency compared to traditional PTR instruments, the Vocus PTR-TOF identifies a large amount of gas-phase signals with elemental composition categories including CH, CHO, CHN, CHS, CHON, CHOS, and others. Multiple hydrocarbons are detected, with carbon numbers up to 20. Particularly, we report the first direct observations of low-volatility diterpenes in the ambient air. The diurnal cycle of diterpenes is similar to that of monoterpenes and sesquiterpenes, but contrary to that of isoprene. Various types of terpene reaction products and intermediates are also characterized. Generally, the more oxidized products from terpene oxidations show a broad peak in the day due to the strong photochemical effects, while the less oxygenated products peak in the early morning and/or in the evening. To evaluate the importance of different formation pathways in terpene chemistry, the reaction rates of terpenes with main oxidants (i.e., hydroxyl radical, OH; ozone, O3; and nitrate radical, NO3) are calculated. For the less oxidized non-nitrate monoterpene oxidation products, their morning peaks likely have contributions from both O3- and OH-initiated monoterpene oxidation. Due to the decreased OH concentration at night, monoterpene ozonolysis becomes more important in the evening. For the monoterpene-derived organic nitrates, oxidations by O3, OH, and NO3 radicals all contribute to their formation, with their relative roles varying considerably over the course of the day. Through a detailed analysis of terpene chemistry, this study demonstrates the capability of the Vocus PTR-TOF in the detection of a wide range of oxidized reaction products in ambient and remote conditions, which highlights its importance in investigating atmospheric oxidation processes.

scholarly journals Substantial secondary organic aerosol formation in a coniferous forest: observations of both day and night time chemistry

2015 ◽  
Vol 15 (20) ◽  
pp. 28005-28035 ◽  
Author(s):  
A. K. Y. Lee ◽  
J. P. D. Abbatt ◽  
W. R. Leaitch ◽  
S.-M. Li ◽  
S. J. Sjostedt ◽  
...  
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Coniferous Forest ◽  
Organic Aerosol ◽  
Organic Nitrates ◽  
Nitrate Radical ◽  
Aerosol Formation ◽  
Radical Chemistry ◽  
Phase Oxidation ◽  
Gas Phase Oxidation

Abstract. Substantial biogenic secondary organic aerosol (BSOA) formation was investigated in a coniferous forest mountain region at Whistler, British Columbia. A largely biogenic aerosol growth episode was observed, providing a unique opportunity to investigate BSOA formation chemistry in a forested environment with limited influence from anthropogenic emissions. Positive matrix factorization of aerosol mass spectrometry (AMS) measurement identified two types of BSOA (BSOA-1 and BSOA-2), which were primarily generated by gas-phase oxidation of monoterpenes and perhaps sesquiterpenes. The temporal variations of BSOA-1 and BSOA-2 can be explained by gas-particle partitioning in response to ambient temperature and the relative importance of different oxidation mechanisms between day and night. While BSOA-1 will arise from gas-phase ozonolysis and nitrate radical chemistry at night, BSOA-2 is less volatile than BSOA-1 and consists of products formed via gas-phase oxidation by the OH radical and ozone during the day. Organic nitrates produced through nitrate radical chemistry can account for 22–33 % of BSOA-1 mass at night. The mass spectra of BSOA-1 and BSOA-2 have higher values of the mass fraction of m/z 91 (f91) compared to the background organic aerosol, and so f91 is used as an indicator of BSOA formation pathways. A comparison between laboratory studies in the literature and our field observations highlights the potential importance of gas-phase formation chemistry of BSOA-2 type materials that may not be captured in smog chamber experiments, perhaps due to the wall loss of gas-phase intermediate products.

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