Radiolysis of methylcyclohexane. III. Pure vapor phase and effects of additives

1967 ◽  
Vol 45 (14) ◽  
pp. 1649-1659 ◽  
Author(s):  
W. J. Holtslander ◽  
G. R. Freeman
Keyword(s):  
Vapor Phase ◽  
Secondary Reaction ◽  
Hydrogen Yield ◽  
Methyl Radicals ◽  
Hydrogen Atoms ◽  
Hydrogen Formation ◽  
Positive Ions ◽  
Total Ionization ◽  
Different Types ◽  
Increasing Temperature

The radiolysis of methylcyclohexene (MCH) vapor was carried out under a variety of conditions. The G-values of the main products at 110°, extrapolated to zero dose, are hydrogen (5.2), methylcyclohexene isomers (2.0), ethylene (1.5), methane (1.3), propylene (0.8), and total dimer (0.3). Other products were also measured.The hydrogen yield was reduced to G = 3.1 by each of the additives, N2O, SF6, and CCL4, and to G = 1.6 by C2H4. Both DI and ND3 increased the total hydrogen yield above the value in pure MCH. In pure MCH approximately 50% of the ions (G(total ionization) = 4.4) resulted in hydrogen formation, whereas in the presence of DI or ND3, 75% of the ions are hydrogen precursors. Thus three different types of positive ions are distinguished in the system: G(M1+) = 2.1, G(M2+) = 1.3, and G(N+) = 1.0.The average ion lifetime with respect to neutralization was 10−3 s. The ion DI−was therefore stable with respect to decomposition to D + I− for a period greater than 10–3 s under the conditions of the experiments (~380 Torr MCH, 110°).The yield of methylcyclohexene isomers increased with increasing temperature and increased upon addition of ND3 or C2H4 to the radiolysis system. The dimer yield was also enhanced by the addition of ND3. This effect was explained by the occurrence of an ionic secondary reaction that destroys methylcyclohexene and (or) methylcyclohexyl radicals in pure MCH.Approximately 85% of the methane is produced by methyl radicals abstracting hydrogen atoms from MCH.

THE RADIOLYSIS OF ETHANOL: II. BINARY VAPOR MIXTURES

1961 ◽  
Vol 39 (9) ◽  
pp. 1843-1847
Author(s):  
J. M. Ramaradhya ◽  
G. R. Freeman
Keyword(s):  
Experimental Data ◽  
Kinetic Parameters ◽  
Vapor Phase ◽  
Reaction Mechanisms ◽  
Marked Decrease ◽  
Hydrogen Yield ◽  
Hydrogen Atoms ◽  
Energy Excitation ◽  
Straight Line ◽  
Vapor Mixtures

Benzene and cyclohexene cause a marked decrease in the hydrogen yield from the vapor phase radiolysis of ethanol.The experimental data were tested against the two reaction mechanisms that gave straight-line plots for the corresponding cyclohexane–protector systems. Both of these mechanisms also gave straight-line plots for the ethanol–protector systems.One mechanism involved scavenging of hydrogen atoms. The values of the kinetic parameters derived from this mechanism are quite similar in the cyclohexane and ethanol systems.The second mechanism involved the transfer of energy (excitation or ionization) from ethanol to the protector. The values of the kinetic parameters derived from this mechanism showed some differences between the ethanol and cyclohexane systems.One possible reason for the lack of resolution between the two reaction mechanisms might be that they both occur to comparable extents. Two mechanisms appear to occur to comparable extents in the liquid cyclohexane system.

Photosensitization by Cd(3P1) Atoms. II. Gas Phase Decomposition of Cyclohexane

1972 ◽  
Vol 50 (13) ◽  
pp. 2010-2016 ◽  
Author(s):  
B. L. Kalra ◽  
A. R. Knight
Keyword(s):  
Quantum Yield ◽  
Gas Phase ◽  
Vapor Phase ◽  
Exposure Time ◽  
Molecular Hydrogen ◽  
Primary Decomposition ◽  
Phase Decomposition ◽  
Hydrogen Atoms ◽  
Hydrogen Formation ◽  
Volatile Products

The photodecomposition of cyclohexane sensitized by Cd(3P1) atoms has been studied in the vapor phase at 355 °C. The primary decomposition gives hydrogen atoms and cyclohexyl radicals. The volatile products of the decomposition are H2, cyclohexene, propylene, ethane, ethylene, methane, propane, butadiene, and methylcyclopentane. Products other than H2 and cyclo-C6H10 arise from unimolecular reactions of cyclohexyl radicals, the most important such process being the production of propylene and allyl radicals. Hydrogen yields decrease rapidly with time because of H-atom scavenging reactions involving olefinic products. The quantum yield of molecular hydrogen formation at the shortest exposure time examined is 0.53.

Radical displacement reactions: The vapor phase reaction of methyl radicals with allyl formate

1968 ◽  
Vol 46 (14) ◽  
pp. 2451-2454
Author(s):  
G. Greig ◽  
J. C. J. Thynne
Keyword(s):  
Vapor Phase ◽  
Phase Reaction ◽  
Displacement Reaction ◽  
Methyl Radicals ◽  
Hydrogen Atoms ◽  
Temperature Range ◽  
Principal Reaction ◽  
Displacement Reactions ◽  
Vapor Phase Reaction

Trideuteromethyl radicals have been reacted in the vapor phase with allyl formate and the principal reaction over the temperature range 100–250 °C has been shown to be the displacement reaction[Formula: see text][Formula: see text]Hydrogen atoms generated by this decomposition also react readily to produce propylene by the reaction[Formula: see text]

scholarly journals PERFECTION OF THE PYROLYSIS PROCESS

2017 ◽  
pp. 113-117
Author(s):  
E. R. Magaril ◽  
R. Z. Magaril ◽  
L. V. Trushkova
Keyword(s):  
Energy Consumption ◽  
Raw Materials ◽  
Specific Energy Consumption ◽  
Relative Reactivity ◽  
Methyl Radicals ◽  
Pyrolysis Process ◽  
Hydrogen Atoms ◽  
Thermal Reactions ◽  
Different Types ◽  
Liquid Products

There were obtained the values of the relative reactivity of different types of bonds in interaction with hydrogen atoms, methyl radicals, as well as values of the effective relative reactivity when using an inert diluent, enabling to improve knowledge about the pyrolysis of raw materials of a given composition. A method was developed for increasing the selectivity of the pyrolysis for the desired products of the process (lower olefins), reducing the yield of liquid products of condensation and specific energy consumption, based on the influence of hydrogen on the thermal reactions of alkanes and alkenes.

γ-Radiolysis of cyclohexane with electron scavengers. VI. N2O and SF6 as electron scavengers in the vapor phase

1968 ◽  
Vol 46 (22) ◽  
pp. 3511-3516 ◽  
Author(s):  
N. H. Sagert ◽  
R. W. Robinson ◽  
A. S. Blair
Keyword(s):  
Carbon Dioxide ◽  
Vapor Phase ◽  
General Mechanism ◽  
Hydrogen Yield ◽  
Neutral Species ◽  
First Order ◽  
Nitrogen Yield

The γ-radiolysis of cyclohexane has been examined in the vapor phase using N2O and SF6 as electron scavengers. Both N2O and SF6 reduce the hydrogen yield from 4.6 to 3.0 G units, indicating that 3.0 G units of hydrogen have neutral species as precursors, while 1.6 G units have electrons as precursors.Radiolysis of cyclohexane vapor with more than 2% N2O produces 10.4 G units of cyclohexene and 11.5 of nitrogen. Carbon dioxide reduces both these yields; the extrapolated value of G(N2) is equal to G(electrons) at infinite CO2 concentration. Thus O− is likely a precursor of that part of the nitrogen yield in excess of G(electrons), and of the cyclohexene yield associated with this nitrogen yield.The first order molecular detachment of hydrogen is unaffected by electron scavengers, showing that most of this first order yield has neutral precursors. The implications for Dyne's general mechanism of hydrocarbon radiolysis are discussed.

RADIATION CHEMISTRY OF CYCLOHEXANE: VI. DILUTE SOLUTIONS OF CARBON TETRACHLORIDE AND CHLOROFORM IN CYCLOHEXANE

1964 ◽  
Vol 42 (3) ◽  
pp. 669-681 ◽  
Author(s):  
J. A. Stone ◽  
P. J. Dyne
Keyword(s):  
Carbon Tetrachloride ◽  
Chemical Reaction ◽  
Physical Process ◽  
Radical Scavenging ◽  
Radiation Chemistry ◽  
Hydrogen Yield ◽  
Halogenated Compounds ◽  
Dilute Solutions ◽  
Hydrogen Atoms

A study of the effect of the addition of small amounts (<3.5%) of the halogenated compounds CCl4, CHCl3, and CDCl3 on the radiolysis of cyclohexane has shown that processes other than radical scavenging occur. At the lowest concentrations of solute that it was practical to employ (0.004 M) cyclohexyl radicals were scavenged without a corresponding reduction in the hydrogen yield. At higher solute concentrations G(H2) was reduced by a physical process which did not involve the scavenging of thermal hydrogen atoms but did lead to chemical reaction involving the solute.

Reactions of free radicals with aromatic compounds in the gaseous phase. I. Kinetics of the reaction of methyl radicals with toluene

1964 ◽  
Vol 17 (12) ◽  
pp. 1329 ◽  
Author(s):  
MFR Mulcahy ◽  
DJ Williams ◽  
JR Wilmshurst
Keyword(s):  
Flow System ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Hydrogen Atoms ◽  
Methyl Group ◽  
Benzyl Radical ◽  
Toluene Molecule ◽  
Benzyl Radicals ◽  
Butyl Peroxide ◽  
Kinetics Of

The kinetics of abstraction of hydrogen atoms from the methyl group of the toluene molecule by methyl radicals at 430-540�K have been determined. The methyl radicals were produced by pyrolysis of di-t-butyl peroxide in a stirred-flow system. The kinetics ,agree substantially with those obtained by previous authors using photolytic methods for generating the methyl radicals. At toluene and methyl-radical concentrations of about 5 x 10-7 and 10-11 mole cm-3 respectively the benzyl radicals resulting from the abstraction disappear almost entirely by combination with methyl radicals at the methylenic position. In this respect the benzyl radical behaves differently from the iso-electronic phenoxy radical, which previous work has shown to combine with a methyl radical mainly at ring positions. The investigation illustrates the application of stirred-flow technique to the study of the kinetics of free-radical reactions.

scholarly journals Evaluation of Biochar Nitrate Extraction Methods

2019 ◽  
Vol 9 (17) ◽  
pp. 3514 ◽  
Author(s):  
Jenna Walsh ◽  
Joseph Sanford ◽  
Rebecca Larson
Keyword(s):  
Extraction Method ◽  
Extraction Efficiency ◽  
Agricultural Soils ◽  
Extraction Methods ◽  
Multiple Methods ◽  
Soil Extraction ◽  
Future Studies ◽  
Different Types ◽  
Increasing Temperature ◽  
Biochar Amendment

Biochar amendment to soil is a method used to mitigate losses of nitrogen leaching through agricultural soils. Multiple methods for extraction of nitrogen have been used, and recent studies have indicated that traditional soil extraction methods underestimate biochar nitrate. This study evaluated the nitrate extraction efficiency of a KCl extraction method under different temperature (20 and 50 °C) and duration (24 and 96 h) conditions. Increasing the duration of extraction from 24 to 96 h did not have a significant impact on extraction efficiency. However, increasing temperature resulted in nitrate extraction efficiencies above 90%. Rinsing the biochar once with deionized (DI) water following filtration after extraction increased the extraction efficiency significantly, but any subsequent rinses were not significant. This study recommends extracting nitrate from biochar using 2 M KCl at 50 °C for a period of 24 h with one additional rinse to increase nitrate recovery above 90%. However, future studies should evaluate this procedure for different types of biochar produced from alternative biomasses and at varying temperatures.

The reaction of hydrogen atoms with ethylene

1970 ◽  
Vol 316 (1527) ◽  
pp. 575-591 ◽  
Keyword(s):  
Hydrogen Atom ◽  
Rate Constant ◽  
Recombination Reaction ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Hydrogen Atoms ◽  
Ethyl Radical ◽  
Cracking Reaction ◽  
Computer Calculations ◽  
First Time

A detailed study has been made of the products from the reaction between hydrogen atoms and ethylene in a discharge-flow system at 290 ± 3 K. Total pressures in the range 8 to 16 Torr (1100 to 2200 Nm -2 ) of argon were used and the hydrogen atom and ethylene flow rates were in the ranges 5 to 10 and 0 to 20 μ mol s -1 , respectively. In agreement with previous work, the main products are methane and ethane ( ~ 95%) together with small amounts of propane and n -butane, measurements of which are reported for the first time. A detailed mechanism leading to formation of all the products is proposed. It is shown that the predominant source of ethane is the recombination of two methyl radicals, the rate of recombination of a hydrogen atom with an ethyl radical being negligible in comparison with the alternative, cracking reaction which produces two methyl radicals. A set of rate constants for the elementary steps in this mechanism has been derived with the aid of computer calculations, which gives an excellent fit with the experimental results. In this set, the values of the rate constant for the addition of a hydrogen atom to ethylene are at the low end of the range of previously measured values but are shown to lead to a more reasonable value for the rate constant of the cracking reaction of a hydrogen atom with an ethyl radical. It is shown that the recombination reaction of a hydrogen atom with a methyl radical, the source of methane, is close to its third-order region.

FISSION FRAGMENT IRRADIATIONS OF HYDROCARBONS: I. YIELD AND ISOTOPIC COMPOSITION OF HYDROGEN FROM MIXTURES OF CYCLOHEXANE AND BENZENE WITH THEIR DEUTERATED ANALOGUES

1964 ◽  
Vol 42 (6) ◽  
pp. 1418-1425 ◽  
Author(s):  
A. W. Boyd ◽  
H. W. J. Connor
Keyword(s):  
Isotopic Composition ◽  
Fission Fragment ◽  
Hydrogen Yield ◽  
Transient Species ◽  
Hydrogen Formation ◽  
Fission Fragments ◽  
Gamma Radiolysis

Cyclohexane and benzene and mixtures of each of these with cyclohexane-d12 and benzene-d6 have been irradiated with fission fragments using thin sources of [Formula: see text]. The hydrogen yield G(H2) for cyclohexane is 7.73, and is only slightly reduced by the addition of benzene. G(H2) for benzene is 2.14. The isotopic composition of the hydrogen from the four mixtures indicates that most is formed in bimolecular processes.To correlate these results with those obtained in gamma radiolysis, a mechanism is proposed based on hydrogen formation by reactions between transient species in both cyclohexane and benzene.

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