Investigation of the Thermal Decomposition of Ketene and of the Reaction CH2 + H2 ⇔ CH3 + H

2001 ◽  
Vol 215 (12) ◽  
Author(s):  
G. Friedrichs ◽  
H.Gg. Wagner
Keyword(s):  
Thermal Decomposition ◽  
Low Temperature ◽  
Shock Waves ◽  
High Temperatures ◽  
Frequency Modulation ◽  
Decomposition Reaction ◽  
Activation Energies ◽  
Unimolecular Decomposition ◽  
First Time ◽  
Singlet Methylene

Using frequency modulation (FM) spectroscopy singlet methylene radicals have been detected for the first time behind shock waves. The thermal decomposition of ketene served as source for metylene radicals at temperatures from 1905 to 2780 K and pressures around 450 mbar. For the unimolecular decomposition reaction, (1) CHAs a first study of a methylene reaction at high temperatures by diretly tracing methylene the reaction of methylene with hydrogen, (8 + 9)log(A comparison with low temperature literature data and the systematics of activation energies of triplet methylene reactions allowed a consistent description of singlet and triplet contributions and of the forward and reverse reaction.

Quantitative FM Spectroscopy at High Temperatures: The Detection of 1CH2 behind Shock Waves

2000 ◽  
Vol 214 (12) ◽  
Author(s):  
G. Friedrichs ◽  
H.Gg. Wagner
Keyword(s):  
High Temperature ◽  
Shock Waves ◽  
High Temperatures ◽  
Frequency Modulation ◽  
Modulation Frequency ◽  
Optical Power ◽  
Time Resolved ◽  
Signal Conversion ◽  
High Modulation ◽  
Singlet Methylene

The technique of time resolved frequency modulation (FM) spectroscopy has been shown to provide a very sensitive means to detect small radicals behind shock waves. Features of high temperature FM spectroscopy behind shock waves will be discussed and a general signal conversion procedure to carry out quantitative concentration measurements will be presented.Using a high modulation frequency, a high modulation index and high total optical power, singlet methylene radicals (α

Mass spectrometric studies of chemical reactions in shock waves: the thermal decomposition of nitrous oxide

1969 ◽  
Vol 47 (4) ◽  
pp. 521-538 ◽  
Author(s):  
S. C. Barton ◽  
J. E. Dove
Keyword(s):  
Thermal Decomposition ◽  
Shock Waves ◽  
Rate Coefficient ◽  
Mass Spectrometric Study ◽  
Mass Spectrometric ◽  
Unimolecular Decomposition ◽  
Reflected Shock ◽  
Secondary Reactions ◽  
Gas Reactions ◽  
Collision Mechanism

Apparatus for the mass spectrometric study of rapid gas reactions in reflected shock waves is described. This apparatus has been applied to the thermal decomposition of 2% N2O in Kr at total gas concentrations of about 1.6 × 10−6 mole cm−3, in the temperature range 1800 to 2800 °K. The principal products of the reaction were found to be N2, O2, NO, and O. The rate coefficient for the unimolecular decomposition of N2O was calculated from the experimental data, and the rates of the secondary reactions between O and N2O were estimated. The possibility of the occurrence of a "weak collision" mechanism in the unimolecular reaction of N2O is discussed.

scholarly journals Improvement in Carbonization Efficiency of Cellulosic Fibres Using Silylated Acetylene and Alkoxysilanes

Fibers ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 84
Author(s):  
Maria Mironova ◽  
Igor Makarov ◽  
Lyudmila Golova ◽  
Markel Vinogradov ◽  
Georgy Shandryuk ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Thermal Behavior ◽  
Comparative Studies ◽  
Decomposition Reaction ◽  
Activation Energies ◽  
Composite Fibers ◽  
Carbon Yield ◽  
Pyrolysis Reaction ◽  
Cellulosic Fibres

Comparative studies of the structure and thermal behavior of cellulose and composite precursors with additives of silyl-substituted acetylene and alkoxysilanes were carried out. It is shown that the introduction of silicon-containing additives into the cellulose matrix influenced the thermal behavior of the composite fibers and the carbon yield after carbonization. Comparison of the activation energies of the thermal decomposition reaction renders it possible to determine the type of additive and its concentration, which reduces the energy necessary for pyrolysis. It is shown that the C/O ratio in the additive and the presence of the Si–C bond affected the activation energy and the temperature of the beginning and the end of the pyrolysis reaction.

Mass spectrometric studies of chemical reactions in shock waves. Part II. The thermal decomposition of diazomethane

1970 ◽  
Vol 48 (23) ◽  
pp. 3623-3634 ◽  
Author(s):  
J. E. Dove ◽  
J. Riddick
Keyword(s):  
Mass Spectrometry ◽  
Thermal Decomposition ◽  
Shock Waves ◽  
Vibrational Energy ◽  
Mass Spectrometric ◽  
Unimolecular Decomposition ◽  
Vibrationally Excited ◽  
Flight Mass Spectrometry ◽  
Concentration Changes ◽  
Products Of Reaction

The thermal decomposition of CH2N2, highly diluted in Kr, has been studied in shock waves by using time-of-flight mass spectrometry to follow concentration changes in the reacting gas. Observations were made at pressures 45 to 95 Torr and temperatures 820 to 1200°K. The principal products of reaction are C2H4, C2H2, and N2. The primary step appears to be a second order unimolecular decomposition of CH2N2 into CH2 and N2; for this step, log k = (9.61 ± 0.21) − (15 800 ± 1 000)/2.303RT(cal mole−1 and cm3 mole s units.) Some decomposition of CH2N2 into HCN and NH is also indicated. The formation of C2H2 is believed to occur through vibrationally excited C2H4, formed by reaction between CH2 and CH2N2. Calculations using the R.R.K.M. theory indicate that 50 + 10% of the energy of this reaction appears as vibrational energy of the product C2H4.

Thermal decomposition of formic acid at high temperatures in shock waves

1982 ◽  
Vol 19 (1) ◽  
pp. 89-96 ◽  
Author(s):  
D.S.Y. Hsu ◽  
W.M. Shaub ◽  
Marlana Blackburn ◽  
M.C. Lin
Keyword(s):  
Thermal Decomposition ◽  
Shock Waves ◽  
Formic Acid ◽  
High Temperatures

scholarly journals Theoretical study of the pyrolysis of β-1,4-xylan: a detailed investigation on unimolecular concerted reactions

2021 ◽  
Vol 23 (4) ◽  
pp. 2605-2621
Author(s):  
M. Goussougli ◽  
B. Sirjean ◽  
P.-A. Glaude ◽  
R. Fournet
Keyword(s):  
Thermal Decomposition ◽  
Theoretical Study ◽  
First Time

A theoretical study of the thermal decomposition of β-1,4-xylan, a model polymer of hemicelluloses, is proposed for the first time.

Shock waves in crystalline dielectrics at low temperature

2002 ◽  
Vol 14 (13) ◽  
pp. 3553-3564 ◽  
Author(s):  
Antonino Valenti ◽  
Mariano Torrisi ◽  
Georgy Lebon
Keyword(s):  
Low Temperature ◽  
Shock Waves

Transformation behavior of yttria stabilized tetragonal zirconia polycrystal–TiB2 composites

2001 ◽  
Vol 16 (7) ◽  
pp. 2158-2169 ◽  
Author(s):  
B. Basu ◽  
J. Vleugels ◽  
O. Van Der Biest
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Low Temperature ◽  
Tetragonal Zirconia ◽  
Mechanical Analysis ◽  
Transformation Behavior ◽  
Thermal Expansion Data ◽  
Thermally Induced ◽  
First Time ◽  
Tetragonal Zirconia Polycrystal

The objective of the present article is to study the influence of TiB2 addition on the transformation behavior of yttria stabilized tetragonal zirconia polycrystals (Y-TZP). A range of TZP(Y)–TiB2 composites with different zirconia starting powder grades and TiB2 phase contents (up to 50 vol%) were processed by the hot-pressing route. Thermal expansion data, as obtained by thermo-mechanical analysis were used to assess the ZrO2 phase transformation in the composites. The thermal expansion hysteresis of the transformable ceramics provides information concerning the transformation behavior in the temperature range of the martensitic transformation and the low-temperature degradation. Furthermore, the transformation behavior and susceptibility to low-temperature degradation during thermal cycling were characterized in terms of the overall amount and distribution of the yttria stabilizer, zirconia grain size, possible dissolution of TiB2 phase, and the amount of residual stress generated in the Y-TZP matrix due to the addition of titanium diboride particles. For the first time, it is demonstrated in the present work that the thermally induced phase transformation of tetragonal zirconia in the Y-TZP composites can be controlled by the intentional addition of the monoclinic zirconia particles into the 3Y-TZP matrix.

Thermal decomposition of formaldehyde at high temperatures

1985 ◽  
Vol 89 (14) ◽  
pp. 3109-3113 ◽  
Author(s):  
Ko Saito ◽  
Terumitsu Kakumoto ◽  
Yoshihiro Nakanishi ◽  
Akira Imamura
Keyword(s):  
Thermal Decomposition ◽  
High Temperatures
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