scholarly journals FTIR product study of the Cl-initiated oxidation products of CFC replacements: (E/Z)-1,2,3,3,3-pentafluoropropene and hexafluoroisobutylene

RSC Advances ◽  
2021 ◽  
Vol 11 (21) ◽  
pp. 12739-12747
Author(s):  
Cynthia B. Rivela ◽  
Rodrigo G. Gibilisco ◽  
Carmen M. Tovar ◽  
Ian Barnes ◽  
Peter Wiesen ◽  
...  
Keyword(s):  
Product Distribution ◽  
Oxidation Products ◽  
Distribution Study ◽  
Product Study

An experimental product distribution study and the atmospheric implications of the reactions of Cl with two fluorinated alkenes is provided.

scholarly journals Investigation of the β-pinene photooxidation by OH in the atmosphere simulation chamber SAPHIR

2016 ◽  
Author(s):  
Martin Kaminski ◽  
Hendrik Fuchs ◽  
Ismail-Hakki Acir ◽  
Birger Bohn ◽  
Theo Brauers ◽  
...  
Keyword(s):  
Degradation Mechanism ◽  
Degradation Process ◽  
Product Distribution ◽  
High Reactivity ◽  
Oxidation Products ◽  
Chemical Mechanism ◽  
Emission Rates ◽  
Photochemical Degradation ◽  
Atmosphere Simulation Chamber ◽  
Simulation Chamber

Abstract. Beside isoprene, monoterpenes are the non-methane volatile organic compounds (VOC) with the highest global emission rates. Due to their high reactivity towards OH, monoterpenes can dominate the radical chemistry of the atmosphere in forested areas. In the present study the photochemical degradation mechanism of β-pinene was investigated in the Jülich atmosphere simulation chamber SAPHIR. The focus of this study is on the OH budget in the degradation process. Therefore the SAPHIR chamber was equipped with instrumentation to measure radicals (OH, HO2, RO2), the total OH reactivity, important OH precursors (O3, HONO, HCHO), the parent VOC beta-pinene, its main oxidation products, acetone and nopinone, and photolysis frequencies. All experiments were carried out under low NOx conditions (≤ 2 ppb) and at atmospheric beta-pinene concentrations (≤ 5 ppb) with and without addition of ozone. For the investigation of the OH budget, the OH production and destruction rates were calculated from measured quantities. Within the limits of accuracy of the instruments, the OH budget was balanced in all β-pinene oxidation experiments. However, even though the OH budget was closed, simulation results from the Master Chemical Mechanism 3.2 showed that the OH production and destruction rates were underestimated by the model. The measured OH and HO2 concentrations were underestimated by up to a factor of two whereas the total OH reactivity was slightly overestimated because of the poor reproduction of the measured nopinone by the model by up to a factor of three. A new, theory-derived first-generation product distribution by Vereecken and Peeters was able to reproduce the measured nopinone time series and the total OH reactivity. Nevertheless the measured OH and HO2 concentrations remained underestimated by the numerical simulations. These observations together with the fact that the measured OH budget was closed suggest the existence of unaccounted sources of HO2.

scholarly journals A mass spectrometric study of secondary organic aerosols formed from the photooxidation of anthropogenic and biogenic precursors in a reaction chamber

2006 ◽  
Vol 6 (12) ◽  
pp. 5279-5293 ◽  
Author(s):  
M. R. Alfarra ◽  
D. Paulsen ◽  
M. Gysel ◽  
A. A. Garforth ◽  
J. Dommen ◽  
...  
Keyword(s):  
Irradiation Time ◽  
Organic Aerosols ◽  
Mass Spectrometric Study ◽  
Product Distribution ◽  
Reaction Chamber ◽  
Oxidation Products ◽  
Effective Density ◽  
Mass Spectral ◽  
Fragmentation Patterns ◽  
The Right

Abstract. An Aerodyne Aerosol Mass Spectrometer (AMS) has been utilised to provide on-line measurements of the mass spectral signatures and mass size distributions of the oxidation products resulting from irradiating 1,3,5-trimethylbenzene (1,3,5-TMB) and α-pinene, separately, in the presence of nitrogen oxide, nitrogen dioxide and propene in a reaction chamber. Mass spectral results indicate that both precursors produce SOA with broadly similar chemical functionality of a highly oxidised nature. However, significant differences occur in the minor mass spectral fragments for the SOA in the two reaction systems, indicating that they have different molecular composition. Nitrogen-containing organic compounds have been observed in the photooxidation products of both precursors, and their formation appeared to be controlled by the temporal variability of NOx. Although the overall fragmentation patterns of the photooxidation products in both systems did not change substantially over the duration of each experiment, the contribution of some individual mass fragments to total mass appeared to be influenced by the irradiation time. The effective densities of the 1,3,5-TMB and α-pinene SOA particles were determined for various particle sizes using the relationship between mobility and vacuum aerodynamic diameters. The effective density for the 1,3,5-TMB SOA ranged from 1.35–1.40 g/cm3, while that for α-pinene SOA ranged from 1.29–1.32 g/cm3. The determined effective densities did not show dependence on irradiation time. Results suggest that further chemical processing of SOA takes place in the real atmosphere, as neither the α-pinene nor the 1,3,5-TMB experimental results reproduce the right relative product distribution between carbonyl-containing and multifunctional carboxylic acid species measured at ambient locations influenced by aged continental organic aerosols.

scholarly journals Investigation of the <i>β</i>-pinene photooxidation by OH in the atmosphere simulation chamber SAPHIR

2017 ◽  
Vol 17 (11) ◽  
pp. 6631-6650 ◽  
Author(s):  
Martin Kaminski ◽  
Hendrik Fuchs ◽  
Ismail-Hakki Acir ◽  
Birger Bohn ◽  
Theo Brauers ◽  
...  
Keyword(s):  
Degradation Mechanism ◽  
Product Distribution ◽  
Oxidation Products ◽  
Chemical Mechanism ◽  
Emission Rates ◽  
Photochemical Degradation ◽  
Alkoxy Radical ◽  
Radical Intermediate ◽  
Atmosphere Simulation Chamber ◽  
Simulation Chamber

Abstract. Besides isoprene, monoterpenes are the non-methane volatile organic compounds (VOCs) with the highest global emission rates. Due to their high reactivity towards OH, monoterpenes can dominate the radical chemistry of the atmosphere in forested areas. In the present study the photochemical degradation mechanism of β-pinene was investigated in the Jülich atmosphere simulation chamber SAPHIR (Simulation of Atmospheric PHotochemistry In a large Reaction Chamber). One focus of this study is on the OH budget in the degradation process. Therefore, the SAPHIR chamber was equipped with instrumentation to measure radicals (OH, HO2, RO2), the total OH reactivity, important OH precursors (O3, HONO, HCHO), the parent VOC β-pinene, its main oxidation products, acetone and nopinone and photolysis frequencies. All experiments were carried out under low-NO conditions ( ≤  300 ppt) and at atmospheric β-pinene concentrations ( ≤  5 ppb) with and without addition of ozone. For the investigation of the OH budget, the OH production and destruction rates were calculated from measured quantities. Within the limits of accuracy of the instruments, the OH budget was balanced in all β-pinene oxidation experiments. However, even though the OH budget was closed, simulation results from the Master Chemical Mechanism (MCM) 3.2 showed that the OH production and destruction rates were underestimated by the model. The measured OH and HO2 concentrations were underestimated by up to a factor of 2, whereas the total OH reactivity was slightly overestimated because the model predicted a nopinone mixing ratio which was 3 times higher than measured. A new, theory-derived, first-generation product distribution by Vereecken and Peeters (2012) was able to reproduce the measured nopinone time series and the total OH reactivity. Nevertheless, the measured OH and HO2 concentrations remained underestimated by the numerical simulations. These observations together with the fact that the measured OH budget was closed suggest the existence of unaccounted sources of HO2. Although the mechanism of additional HO2 formation could not be resolved, our model studies suggest that an activated alkoxy radical intermediate proposed in the model of Vereecken and Peeters (2012) generates HO2 in a new pathway, whose importance has been underestimated so far. The proposed reaction path involves unimolecular rearrangement and decomposition reactions and photolysis of dicarbonyl products, yielding additional HO2 and CO. Further experiments and quantum chemical calculations have to be made to completely unravel the pathway of HO2 formation.

scholarly journals A mass spectrometric study of secondary organic aerosols formed from the photooxidation of anthropogenic and biogenic precursors in a reaction chamber

2006 ◽  
Vol 6 (4) ◽  
pp. 7747-7789 ◽  
Author(s):  
M. R. Alfarra ◽  
D. Paulsen ◽  
M. Gysel ◽  
A. A. Garforth ◽  
J. Dommen ◽  
...  
Keyword(s):  
Irradiation Time ◽  
Organic Aerosols ◽  
Mass Spectrometric Study ◽  
Product Distribution ◽  
Reaction Chamber ◽  
Oxidation Products ◽  
Effective Density ◽  
Mass Spectral ◽  
Fragmentation Patterns ◽  
The Right

Abstract. An Aerodyne Aerosol Mass Spectrometer (AMS) has been utilised to provide on-line measurements of the mass spectral signatures and mass size distributions of the oxidation products resulting from irradiating 1,3,5-trimethylbenzene (1,3,5-TMB) and α-pinene, separately, in the presence of nitrogen oxide, nitrogen dioxide and propene in a reaction chamber. Mass spectral results indicate that both precursors produce SOA with broadly similar chemical functionality of a highly oxidised nature. However, significant differences occur in the minor mass spectral fragments for the SOA in the two reaction systems, indicating that they have different molecular composition. Nitrogen-containing organic compounds have been observed in the photooxidation products of both precursors, and their formation appeared to be controlled by the temporal variability of NOx. Although the overall fragmentation patterns of the photooxidation products in both systems did not change substantially over the duration of each experiment, the contribution of some individual mass fragments to total mass appeared to be influenced by the irradiation time. The effective densities of the 1,3,5-TMB and α-pinene SOA particles were determined for various particle sizes using the relationship between mobility and vacuum aerodynamic diameters. The effective density for the TMB-SOA ranged from 1.35–1.40 g/cm3, while that for α-pinene SOA ranged from 1.29–1.32 g/cm3. The determined effective densities did not show dependence on irradiation time. Results suggest that further chemical processing of SOA takes place in the real atmosphere, as neither the α-pinene nor the 1,3,5-TMB experimental results reproduce the right relative product distribution between carbonyl-containing and multifunctional carboxylic acid species measured at ambient locations influenced by aged continental organic aerosols.

scholarly journals A product study of the isoprene+NO<sub>3</sub> reaction

2009 ◽  
Vol 9 (14) ◽  
pp. 4945-4956 ◽  
Author(s):  
A. E. Perring ◽  
A. Wisthaler ◽  
M. Graus ◽  
P. J. Wooldridge ◽  
A. L. Lockwood ◽  
...  
Keyword(s):  
Thermal Dissociation ◽  
Organic Aerosol ◽  
Proton Transfer Reaction ◽  
Product Formation ◽  
Oxidation Products ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Isoprene Nitrates ◽  
Additional Constraints ◽  
Product Study

Abstract. Oxidation of isoprene through reaction with NO3 radicals is a significant sink for isoprene that persists after dark. The main products of the reaction are multifunctional nitrates. These nitrates constitute a significant NOx sink in the nocturnal boundary layer and they likely play an important role in formation of secondary organic aerosol. Products of the isoprene+NO3 reaction will, in many locations, be abundant enough to affect nighttime radical chemistry and to persist into daytime where they may represent a source of NOx. Product formation in the isoprene + NO3 reaction was studied in a smog chamber at Purdue University. Isoprene nitrates and other hydrocarbon products were observed using Proton Transfer Reaction-Mass Spectrometry (PTR-MS) and reactive nitrogen products were observed using Thermal Dissociation–Laser Induced Fluorescence (TD-LIF). The organic nitrate yield is found to be 65±12% of which the majority was nitrooxy carbonyls and the combined yield of methacrolein and methyl vinyl ketone (MACR+MVK) is found to be ∼10%. PTR-MS measurements of nitrooxy carbonyls and TD-LIF measurements of total organic nitrates agreed well. The PTR-MS also observed a series of minor oxidation products which were tentatively identified and their yields quantified These other oxidation products are used as additional constraints on the reaction mechanism.

Aerobic liquid-phase oxidation of p-xylene over metalloporphyrins

2007 ◽  
Vol 11 (07) ◽  
pp. 524-530 ◽  
Author(s):  
Quan Jiang ◽  
Hai-Yang Hu ◽  
Can-Cheng Guo ◽  
Qiang Liu ◽  
Jian-Xin Song ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Terephthalic Acid ◽  
Oxidation Process ◽  
Product Distribution ◽  
Oxidation Products ◽  
Reaction Parameters ◽  
Efficient Catalyst ◽  
Product Distributions ◽  
Phase Oxidation ◽  
Intermediate Oxidation

The five metalloporphyrins ( T (p- Cl ) PPM , M = Fe , Mn , Co , Cu , Zn ) with different metal nuclei were synthesized, and their catalytic aerobic liquid-phase oxidations of p-xylene into p-toluic acid, p-toluic aldehyde and terephthalic acid using a low concentration of acetic acid as solvent without any halide additives, were studied. The p-xylene conversions and the oxidation product distributions were found to be affected by the structures and concentration of the metalloporphyrins as well as the reaction parameters such as time, temperature and air pressure. The formation of some intermediate oxidation products in the oxidation process also influenced the reaction conversions and the product distribution. Among the metalloporphyrins used, tetrakis(p-chlorophenylporphinato)manganese chloride ( T (p- Cl ) PPMnCl ) was the most efficient catalyst for the oxidation of p-xylene. Under the conditions of 180 °C and 2.0 MPa, 44% conversion of p-xylene and 85% selectivity of p-toluic acid were obtained. Based on the results obtained, a preliminary mechanism of the oxidation of p-xylene over metalloporphyrins was proposed.

Product distribution study of the Cl-atom initiated oxidation of ethyl methyl sulfide and diethyl sulfide

2014 ◽  
Vol 85 ◽  
pp. 41-47 ◽  
Author(s):  
Gabriela Oksdath-Mansilla ◽  
Alicia B. Peñéñory ◽  
Ian Barnes ◽  
Peter Wiesen ◽  
Mariano A. Teruel
Keyword(s):  
Product Distribution ◽  
Diethyl Sulfide ◽  
Methyl Sulfide ◽  
Distribution Study ◽  
Ethyl Methyl ◽  
Cl Atom

FTIR Product Distribution Study of the Cl and OH Initiated Degradation of Methyl Acrylate at Atmospheric Pressure

2010 ◽  
Vol 44 (18) ◽  
pp. 7031-7036 ◽  
Author(s):  
María B. Blanco ◽  
Iustinian Bejan ◽  
Ian Barnes ◽  
Peter Wiesen ◽  
Mariano A. Teruel
Keyword(s):  
Methyl Acrylate ◽  
Atmospheric Pressure ◽  
Product Distribution ◽  
Distribution Study

Oxidation sites in dealuminated mordenite. A combined EPR, NMR and product distribution study

1996 ◽  
Vol 92 (11) ◽  
pp. 2027 ◽  
Author(s):  
Gillian Harvey ◽  
Roel Prins ◽  
Rowena Crockett ◽  
Emil Roduner
Keyword(s):  
Product Distribution ◽  
Distribution Study

scholarly journals Emissions and ambient distributions of Biogenic Volatile Organic Compounds (BVOC) in a Ponderosa pine ecosystem: interpretation of PTR-MS mass spectra

2009 ◽  
Vol 9 (5) ◽  
pp. 20819-20852
Author(s):  
S. Kim ◽  
T. Karl ◽  
A. Guenther ◽  
G. Tyndall ◽  
J. Orlando ◽  
...  
Keyword(s):  
Ponderosa Pine ◽  
Oxidation Product ◽  
Mass Spectra ◽  
Forest Canopy ◽  
Rocky Mountain ◽  
Proton Transfer Reaction ◽  
Product Distribution ◽  
Oxidation Products ◽  
Photochemical Process ◽  
Wide Range

Abstract. Two proton-transfer-reaction mass spectrometry systems were deployed at the Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen-Southern Rocky Mountain 2008 field campaign (BEACHON-SRM08; July to September 2008) at the Manitou Forest observatory in a Ponderosa pine woodland near Woodland Park, Colorado USA to simultaneously measure BVOC emissions and ambient distributions of their oxidation products. Here, we present mass spectral analysis in a wide range of masses (m/z=40+ to 210+) to assess our understanding of BVOC emissions and their photochemical process inside of the forest canopy. The biogenic terpenoids, 2-methyl-3-butene-2-ol (MBO, 50.2%) and several monoterpenes (MT, 33.5%) were identified as the dominant BVOC emissions from a transmission corrected mass spectrum, averaged over the daytime (11 am to 3 p.m., local time) of three days. To assess contributions of oxidation products of local BVOC, we calculate a oxidation product spectrum with the OH- and ozone-initiated oxidation product distribution mass spectra of two major BVOC at the ecosystem (MBO and β-pinene) that were observed from laboratory oxidation experiments. A majority (~73%) of the total signal could be explained by known compounds. The remainder are attributed to oxidation products of BVOC, emitted from nearby ecosystems and transported to the site, and oxidation products of unidentified BVOC emitted from the Ponderosa pine ecosystem.

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