scholarly journals Review of "Identification of Gas-phase Pyrolysis Products in a Prescribed Fire ..."

2019 ◽  
Author(s):  
Anonymous
Keyword(s):  
Gas Phase ◽  
Prescribed Fire ◽  
Pyrolysis Products

scholarly journals Identification of gas-phase pyrolysis products in a prescribed fire: first detections using infrared spectroscopy for naphthalene, methyl nitrite, allene, acrolein and acetaldehyde

2019 ◽  
Vol 12 (1) ◽  
pp. 763-776 ◽  
Author(s):  
Nicole K. Scharko ◽  
Ashley M. Oeck ◽  
Russell G. Tonkyn ◽  
Stephen P. Baker ◽  
Emily N. Lincoln ◽  
...  
Keyword(s):  
Gas Phase ◽  
Prescribed Fire ◽  
Wildland Fire ◽  
Pyrolysis Products ◽  
Prescribed Burns ◽  
Methyl Nitrite ◽  
Spectral Components ◽  
Volatile Organic ◽  
Pine Stands ◽  
Many Sources

Abstract. Volatile organic compounds (VOCs) are emitted from many sources, including wildland fire. VOCs have received heightened emphasis due to such gases' influential role in the atmosphere, as well as possible health effects. We have used extractive infrared (IR) spectroscopy on recent prescribed burns in longleaf pine stands and herein report the first detection of five compounds using this technique. The newly reported IR detections include naphthalene, methyl nitrite, allene, acrolein and acetaldehyde. We discuss the approaches used for detection, particularly the software methods needed to fit the analyte and multiple (interfering) spectral components within the selected spectral micro-window(s). We also discuss the method's detection limits and related parameters such as spectral resolution.

scholarly journals Gas-Phase Pyrolysis Products Emitted by Prescribed Fires in Pine Forests with a Shrub Understory in the Southeastern United States

2019 ◽  
Author(s):  
Nicole K. Scharko ◽  
Ashley M. Oeck ◽  
Tanya L. Myers ◽  
Russell G. Tonkyn ◽  
Catherine A. Banach ◽  
...  
Keyword(s):  
Gas Phase ◽  
Pine Forests ◽  
Prescribed Fires ◽  
Pyrolysis Products ◽  
Prescribed Burns ◽  
Extraction Device ◽  
Dominant Process ◽  
Pyrolysis Gases ◽  
Manual Extraction ◽  
Emission Ratios

Abstract. In this study we capture and identify pyrolysis gases from prescribed burns conducted in pine forests with a shrub understory using a manual extraction device. The device selectively sampled emissions ahead of the flame front, minimizing collection of oxidized gases, with the captured gases analyzed in the laboratory using infrared absorption spectroscopy. Results show that emission ratios (ER) relative to CO for ethene, and acetylene were significantly greater than previous fire studies, suggesting that the sample device was able to collect gases prior to ignition. Further evidence that ignition had not begun was corroborated by novel infrared detections of several species, in particular naphthalene. With regards to oxygenated species, several aldehydes (acrolein, furaldehyde, acetaldehyde, formaldehyde) and the carboxylic acids (formic, acetic) were all observed; results show that ERs for acetaldehyde were noticeably greater while ERs for formaldehyde and acetic acid were lower compared to other studies. The acetylene-to-furan ratio also suggests that high temperature pyrolysis was the dominant process generating the collected gases. This hypothesis is further supported by the presence of HCN and the absence of NH3.

scholarly journals Development and Analysis of the Physicochemical and Mechanical Properties of Diorite-Reinforced Epoxy Composites

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2421
Author(s):  
Amirbek Bekeshev ◽  
Anton Mostovoy ◽  
Yulia Kadykova ◽  
Marzhan Akhmetova ◽  
Lyazzat Tastanova ◽  
...  
Keyword(s):  
Gas Phase ◽  
Thermal Destruction ◽  
Epoxy Polymer ◽  
Epoxy Composite ◽  
Chemical Interaction ◽  
Strength Properties ◽  
Epoxy Composites ◽  
Mineral Filler ◽  
Pyrolysis Products ◽  
Thermal Stability Of

The aim of this paper is to study the effect of a polyfunctional modifier oligo (resorcinol phenyl phosphate) with terminal phenyl groups and a dispersed mineral filler, diorite, on the physicochemical and deformation-strength properties of epoxy-based composites. The efficiency of using diorite as an active filler of an epoxy polymer, ensuring an increase in strength and a change in the physicochemical properties of epoxy composites, has been proven. We selected the optimal content of diorite both as a structuring additive and as a filler in the composition of the epoxy composite (0.1 and 50 parts by mass), at which diorite reinforces the epoxy composite. It has been found that the addition of diorite into the epoxy composite results in an increase in the Vicat heat resistance from 132 to 140–188 °C and increases the thermal stability of the epoxy composite, which is observed in a shift of the initial destruction temperature to higher temperatures. Furthermore, during the thermal destruction of the composite, the yield of carbonized structures increases (from 54 to 70–77% of the mass), preventing the release of volatile pyrolysis products into the gas phase, which leads to a decrease in the flammability of the epoxy composite. The efficiency of the functionalization of the diorite surface with APTES has been proven, which ensures chemical interaction at the polymer matrix/filler interface and also prevents the aggregation of diorite particles, which, in general, provides an increase in the strength characteristics of epoxy-based composite materials by 10–48%.

A mass spectrometer for studying chemical reactions

1963 ◽  
Vol 274 (1358) ◽  
pp. 285-292 ◽  
Keyword(s):  
Electron Beam ◽  
Gas Phase ◽  
Mass Spectrometer ◽  
Ion Source ◽  
Line Of Sight ◽  
Pyrolysis Products ◽  
Ionization Region ◽  
Differential Pumping ◽  
Hot Filament ◽  
Phase Chemical

This paper describes a mass spectrometer designed to study gas-phase chemical kinetics. An ion source has been constructed which incorporates a differentially pumped, electron beam filament chamber, and line-of-sight access from the sampling pinhole to the ionization region. Experiments are described which test the effectiveness of differential pumping in reducing contamination of the sample by pyrolysis products formed from the sample on the hot filament.

scholarly journals Identification of Gas-phase Pyrolysis Products in a Prescribed Fire: Seminal Detections Using Infrared Spectroscopy for Naphthalene, Methyl Nitrite, Allene, Acrolein and Acetaldehyde

2018 ◽  
Author(s):  
Nicole K. Scharko ◽  
Ashley M. Oeck ◽  
Russell G. Tonkyn ◽  
Stephen P. Baker ◽  
Emily N. Lincoln ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Prescribed Fire ◽  
Wildland Fire ◽  
Individual Species ◽  
Pyrolysis Products ◽  
Prescribed Burns ◽  
Methyl Nitrite ◽  
Spectral Components ◽  
Volatile Organic ◽  
Many Sources

Abstract. Volatile organic compounds (VOCs) are emitted from many sources, including wildland fire; VOCs have received heightened emphasis due to such gases' influential role in the atmosphere, as well as possible health effects. We have used extractive infrared (IR) spectroscopy on recent prescribed burns in longleaf pine stands and herein report seminal detection of five compounds using this technique. The newly reported IR detections include naphthalene, methyl nitrite, allene, acrolein and acetaldehyde. We discuss the approaches used for detection, particularly the software methods needed to fit the analyte and multiple (interfering) spectral components within the selected spectral micro-window(s). We also discuss the method's detection limits and individual species' context in terms of atmospheric chemistry.

Impact of gas-phase chemistry on the composition of biomass pyrolysis products

2015 ◽  
Vol 122 (3) ◽  
pp. 1089-1098 ◽  
Author(s):  
Alexander Kozlov ◽  
Denis Svishchev ◽  
Igor Donskoy ◽  
Vitaly Shamansky
Keyword(s):  
Gas Phase ◽  
Biomass Pyrolysis ◽  
Pyrolysis Products ◽  
Gas Phase Chemistry ◽  
Phase Chemistry

scholarly journals Online measurements of the emissions of intermediate-volatility and semi-volatile organic compounds from aircraft

2013 ◽  
Vol 13 (3) ◽  
pp. 8065-8100
Author(s):  
E. S. Cross ◽  
J. F. Hunter ◽  
A. J. Carrasquillo ◽  
J. P. Franklin ◽  
S. C. Herndon ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Volatile Organic Compounds ◽  
Gas Phase ◽  
Organic Compounds ◽  
Operating Conditions ◽  
Organic Vapors ◽  
Pyrolysis Products ◽  
Volatile Organic ◽  
Online Measurements ◽  
Unburned Fuel

Abstract. A detailed understanding of the climate and air quality impacts of aviation requires detailed measurements of the emissions of intermediate-volatility and semi-volatile organic compounds (I/SVOCs) from aircraft. Currently both the amount and chemical composition of aircraft I/SVOC emissions remain poorly characterized. Here we characterize I/SVOC emissions from aircraft, using a novel instrument for the online, quantitative measurement of the mass loading and composition of low-volatility organic vapors. Emissions from the NASA DC8 aircraft were sampled on the ground, 143 m downwind of the engines and characterized as a function of engine power from ground idle (~4% maximum rated thrust) through 85% power. Results show that I/SVOC emissions are highest during engine-idle operating conditions, with decreasing but non-zero I/SVOC emissions at higher engine powers. Comparison of I/SVOC emissions with total hydrocarbon (THC) measurements, VOC measurements, and an established emissions profile indicates that I/SVOCs comprise 10–20% of the total organic gas phase emissions at idle, and an increasing fraction of the total gas phase organic emissions at higher powers. Positive matrix factorization of online mass spectra is used to identify three distinct types of I/SVOC emissions: aliphatic, aromatic and oxygenated. The volatility and chemical composition of the emissions suggest that unburned fuel is the dominant source of I/SVOCs at idle, while pyrolysis products make up an increasing fraction of the I/SVOCs at higher powers. Oxygenated I/SVOC emissions were detected at lower engine powers (≤30%) and may be linked to cracked, partially oxidized or unburned fuel components.

scholarly journals Online measurements of the emissions of intermediate-volatility and semi-volatile organic compounds from aircraft

2013 ◽  
Vol 13 (15) ◽  
pp. 7845-7858 ◽  
Author(s):  
E. S. Cross ◽  
J. F. Hunter ◽  
A. J. Carrasquillo ◽  
J. P. Franklin ◽  
S. C. Herndon ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Volatile Organic Compounds ◽  
Gas Phase ◽  
Organic Compounds ◽  
Operating Conditions ◽  
Organic Vapors ◽  
Pyrolysis Products ◽  
Volatile Organic ◽  
Online Measurements ◽  
Unburned Fuel

Abstract. A detailed understanding of the climate and air quality impacts of aviation requires measurements of the emissions of intermediate-volatility and semi-volatile organic compounds (I/SVOCs) from aircraft. Currently both the amount and chemical composition of aircraft I/SVOC emissions remain poorly characterized. Here we characterize I/SVOC emissions from aircraft, using a novel instrument for the online, quantitative measurement of the mass loading and composition of low-volatility organic vapors. Emissions from the NASA DC8 aircraft were sampled on the ground 143 m downwind of the engines and characterized as a function of engine power from idle (4% maximum rated thrust) through 85% power. Results show that I/SVOC emissions are highest during engine idle operating conditions, with decreasing but non-zero I/SVOC emissions at higher engine powers. Comparison of I/SVOC emissions with total hydrocarbon (THC) measurements, VOC measurements, and an established emissions profile indicates that I/SVOCs comprise 10–20% of the total organic gas-phase emissions at idle, and an increasing fraction of the total gas-phase organic emissions at higher powers. Positive matrix factorization of online mass spectra is used to identify three distinct types of I/SVOC emissions: aliphatic, aromatic and oxygenated. The volatility and chemical composition of the emissions suggest that unburned fuel is the dominant source of I/SVOCs at idle, while pyrolysis products make up an increasing fraction of the I/SVOCs at higher powers. Oxygenated I/SVOC emissions were detected at lower engine powers (≤30%) and may be linked to cracked, partially oxidized or unburned fuel components.

Residual Gas Reactions in the Electron Microscope: I. Qualitative Observations on the Water Gas Reaction

1968 ◽  
Vol 26 ◽  
pp. 292-293
Author(s):  
Richard E. Hartman ◽  
Roberta S. Hartman ◽  
Peter L. Ramos
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Gas Phase ◽  
Absolute Temperature ◽  
Residual Gas ◽  
Gas Reactions ◽  
Image Position ◽  
The Right ◽  
Water Gas ◽  
Thinning Rate

The action of water and the electron beam on organic specimens in the electron microscope results in the removal of oxidizable material (primarily hydrogen and carbon) by reactions similar to the water gas reaction .which has the form:The energy required to force the reaction to the right is supplied by the interaction of the electron beam with the specimen.The mass of water striking the specimen is given by:where u = gH2O/cm2 sec, PH2O = partial pressure of water in Torr, & T = absolute temperature of the gas phase. If it is assumed that mass is removed from the specimen by a reaction approximated by (1) and that the specimen is uniformly thinned by the reaction, then the thinning rate in A/ min iswhere x = thickness of the specimen in A, t = time in minutes, & E = efficiency (the fraction of the water striking the specimen which reacts with it).

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