Tetrachloroethylene as an accelerator of propane oxidation

1964 ◽  
Vol 277 (1369) ◽  
pp. 279-288 ◽  
Keyword(s):  
Gas Phase ◽  
Maximum Rate ◽  
Pressure Change ◽  
Product Formation ◽  
Chain Mechanism ◽  
Phase Oxidation ◽  
Gas Phase Oxidation ◽  
Simple Chain ◽  
Catalyzed Reactions ◽  
Key Steps

Tetrachloroethylene and the other chloroethylenes accelerate the gas-phase oxidation of propane in the `low-temperature ’ region, the relation of pressure change to reactant consumption and final product formation being not significantly modified in the catalyzed reaction. The value of the maximum rate in the presence of tetrachloroethylene is given fairly closely by the expression (ρmax.) [C 2 Cl 4 ] / (ρmax.) 0 = 1 + constant x [C 2 Cl 4 ]. The form of this differs from th at found in the chloroform-catalyzed reaction, (ρmax.) [CHCl 3 ] / (ρmax.) 0 = 1 + constant x [CHCl 3 ]/[ Pr H], and suggests th at the key steps are R O · 2 +CCl 2 = CCl 2 ⇌ ROOCCl 2 CCl · 2 R OOCCl 2 CCl · 2 + R H → Cl + ... A slow formation of hydrogen chloride occurs during reaction. A simple chain mechanism approximately reproduces the experimental kinetic formula. Some results for trichloroethylene indicate a type of behaviour intermediate between the chloroform- and tetrachloroethylene-catalyzed reactions.

Chloroform as an accelerator of propane oxidation

1963 ◽  
Vol 274 (1358) ◽  
pp. 413-426 ◽  
Keyword(s):  
Gas Phase ◽  
Maximum Rate ◽  
Isotopic Exchange ◽  
Pressure Change ◽  
Product Formation ◽  
Pressure Measurements ◽  
Chain Mechanism ◽  
Phase Oxidation ◽  
Gas Phase Oxidation ◽  
Simple Chain

Chloroform and the other chloromethanes, except carbon tetrachloride, accelerate the gas-phase oxidation of propane in the 'low-temperature' region. The relation of pressure change to reactant consumption and final product formation is not significantly modified in the catalyzed reaction, which can still be followed by pressure measurements. The value of the maximum rate in the presence of chloroform is given fairly closely by the expression (( ρ max .) [CHCL 3 ])/( ρ max .) 0 = 1 + constant x [CHCI 3 ]/[ R H]. The form of this suggests that, in the rate-determining steps, chloroform and paraffin are involved in analogous processes, and the key step is postulated to be R O 2 · + CHCI 3 → R OOH + CCl 3 · which re-inforces the reaction R O 2 · + R H → R OOH + R · in competing with those steps normally leading to degradation of R O 2 · radicals. Since little or no isotopic exchange occurs when CDCl 3 is used in place of CHCl 3 , the radical CCl 3 · does not regenerate chloroform, but initiates chains of the type CCl 3 ·→ ·CCl 2 · + Cl·, Cl· + R H → HCl + R · A slow consumption of chloroform (the oxidation of which is unimportant in the absence of propane) occurs, together with a slow build-up of hydrogen chloride. With certain approximations, a simple chain mechanism reproduces the experimental kinetic formula.

Gas-phase oxidation of hexene-1

1958 ◽  
Vol 244 (1238) ◽  
pp. 345-354 ◽  
Keyword(s):  
Oxygen Consumption ◽  
Gas Phase ◽  
Maximum Rate ◽  
Reaction Rate ◽  
Pressure Change ◽  
Early Stages ◽  
Unusual Form ◽  
Phase Oxidation ◽  
Rate Of Oxygen Consumption ◽  
Gas Phase Oxidation

An investigation has been made of the oxidation of hexene-1 at 263°C. The unusual form of dependency of reaction rate on hydrocarbon pressure obtained when the maximum rate of pressure change is used as a measure of reaction rate is explained by the fact that much of the oxygen is consumed before the maximum rate of pressure change is attained. This, and the observation that the maximum rate of oxygen consumption exhibits a different dependence on hexene concentration compared with the maximum rate of pressure change confirm that maximum rate of pressure change is an invalid measure of reaction rate. Analyses have been made for certain intermediates and products throughout the course of the reaction, and it has been possible to explain many of the experimental features in terms of ideas previously propounded. A decrease in pressure which in many experiments precedes the rapid increase in pressure is attributed to polymerization reactions which predominated over oxidative degradations in the early stages of the reaction, particularly when the olefin is present in excess.

Kinetics of the gas-phase oxidation of methanol catalysed by hydrogen bromide

1964 ◽  
Vol 17 (5) ◽  
pp. 551
Author(s):  
JJ Batten
Keyword(s):  
Nitric Oxide ◽  
Gas Phase ◽  
Maximum Rate ◽  
Hydrogen Bromide ◽  
Oxidation Of Methanol ◽  
Catalysed Reaction ◽  
Phase Oxidation ◽  
Gas Phase Oxidation ◽  
Kinetics Of ◽  
Uncatalysed Reaction

The homogeneous, gas-phase oxidation of methanol, catalysed by small amounts of hydrogen bromide, has been studied in a boric acid coated vessel at 310�. Under these conditions no reaction takes place in the absence of hydrogen bromide. The kinetics of the reaction and the rate of accumulation of formaldehyde in the products are compared with previously published data on the nitric oxide catalysed reaction at 310� and the uncatalysed reaction at 390�, i.e. at comparable rates of oxidation. The kinetics of the reaction were studied by means of pressure-time curves, and these were found to be of a similar shape to those of the uncatalysed reaction at 390�, and the nitric oxide catalysed reaction at 310�. The maximum rate was increased by the addition of "inert" gas. This rate varied as the methanol and hydrogen bromide pressures raised to the powers 0.7 and 1.3 respectively. On the other hand, increase in the oxygen pressure inhibited the maximum rate. The overall activation energy was 27 kcal mole-1. These kinetic data are similar to those of the nitric oxide catalysed reaction but differ markedly from those of the uncatalysed process at 390�. Under similar conditions, 15 mmHg hydrogen bromide were required to give a rate approximately equal to that obtained when using 2 mmHg nitric oxide. The maximum pressure of formaldehyde in the products was only about one-tenth of that obtained under similar conditions in the other two oxidations.

Kinetic analysis of coupled gas phase oxidation reaction of secondary alcohols on iridium

1979 ◽  
Vol 44 (5) ◽  
pp. 1590-1607
Author(s):  
Pavel Slouka ◽  
Ludvík Beránek
Keyword(s):  
Gas Phase ◽  
Rate Equations ◽  
Secondary Alcohols ◽  
Chain Mechanism ◽  
Competitive Reactions ◽  
Phase Oxidation ◽  
Separate Treatment ◽  
Gas Phase Oxidation ◽  
A Chain ◽  
Kinetics Of

Kinetics of partial gas phase oxidation of 2-butanol (B) and 4-methyl-2-pentanol (M) to ketones on Ir/C catalyst at 150 °C has been studied. In single reactions alcohol B was 4-7times more reactive than alcohol M, in competitive reactions the latter was twice as reactive as the former. Separate treatment of rate data for single and competitive reactions of both alcohols showed that each set could be described by nearly the same set of equations on 99% confidence level, including, of course, very different kinetic models. Confrontation of the kinetics of single and competitive reactions (comparison of the values of corresponding constants of rate equations) and the analysis of relative reactivities revealed the unfitness of Langmuir-Hinshelwood and redox models in this case. A model taking into account nonhomogeneity of the surface and a model derived on the basis of a chain mechanism would be able to describe better and in consistent way the kinetics of single and competitive reactions as well as the observed inversion of the reactivity of studied alcohols.

Gas phase oxidation of furfural to maleic anhydride on V 2 O 5 /γ-Al 2 O 3 catalysts: Reaction conditions to slow down the deactivation

2017 ◽  
Vol 348 ◽  
pp. 265-275 ◽  
Author(s):  
N. Alonso-Fagúndez ◽  
M. Ojeda ◽  
R. Mariscal ◽  
J.L.G. Fierro ◽  
M. López Granados
Keyword(s):  
Maleic Anhydride ◽  
Gas Phase ◽  
Reaction Conditions ◽  
Phase Oxidation ◽  
Gas Phase Oxidation

scholarly journals Volatility of secondary organic aerosol during OH radical induced ageing

2011 ◽  
Vol 11 (21) ◽  
pp. 11055-11067 ◽  
Author(s):  
K. Salo ◽  
M. Hallquist ◽  
Å. M. Jonsson ◽  
H. Saathoff ◽  
K.-H. Naumann ◽  
...  
Keyword(s):  
Gas Phase ◽  
Organic Aerosol ◽  
Oh Radical ◽  
High Concentration ◽  
Volatile Material ◽  
Phase Oxidation ◽  
Gas Phase Oxidation ◽  
Institute Of Technology ◽  
Set Up ◽  
Pinic Acid

Abstract. The aim of this study was to investigate oxidation of SOA formed from ozonolysis of α-pinene and limonene by hydroxyl radicals. This paper focuses on changes of particle volatility, using a Volatility Tandem DMA (VTDMA) set-up, in order to explain and elucidate the mechanism behind atmospheric ageing of the organic aerosol. The experiments were conducted at the AIDA chamber facility of Karlsruhe Institute of Technology (KIT) in Karlsruhe and at the SAPHIR chamber of Forchungzentrum Jülich (FZJ) in Jülich. A fresh SOA was produced from ozonolysis of α-pinene or limonene and then aged by enhanced OH exposure. As an OH radical source in the AIDA-chamber the ozonolysis of tetramethylethylene (TME) was used while in the SAPHIR-chamber the OH was produced by natural light photochemistry. A general feature is that SOA produced from ozonolysis of α-pinene and limonene initially was rather volatile and becomes less volatile with time in the ozonolysis part of the experiment. Inducing OH chemistry or adding a new portion of precursors made the SOA more volatile due to addition of new semi-volatile material to the aged aerosol. The effect of OH chemistry was less pronounced in high concentration and low temperature experiments when lower relative amounts of semi-volatile material were available in the gas phase. Conclusions drawn from the changes in volatility were confirmed by comparison with the measured and modelled chemical composition of the aerosol phase. Three quantified products from the α-pinene oxidation; pinonic acid, pinic acid and methylbutanetricarboxylic acid (MBTCA) were used to probe the processes influencing aerosol volatility. A major conclusion from the work is that the OH induced ageing can be attributed to gas phase oxidation of products produced in the primary SOA formation process and that there was no indication on significant bulk or surface reactions. The presented results, thus, strongly emphasise the importance of gas phase oxidation of semi- or intermediate-volatile organic compounds (SVOC and IVOC) for atmospheric aerosol ageing.

Experimental and Modeling Study of the Selective Homogeneous Gas Phase Oxidation of Methane to Methanol

1995 ◽  
Vol 34 (4) ◽  
pp. 1044-1059 ◽  
Author(s):  
Rune Lodeng ◽  
Odd A. Lindvaag ◽  
Paal Soraker ◽  
Per T. Roterud ◽  
Olav T. Onsager
Keyword(s):  
Gas Phase ◽  
Oxidation Of Methane ◽  
Phase Oxidation ◽  
Gas Phase Oxidation ◽  
Modeling Study
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