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.

Effect of surface on the gas-phase oxidation of methanol catalysed by nitric oxide

1964 ◽  
Vol 17 (5) ◽  
pp. 539
Author(s):  
JJ Batten
Keyword(s):  
Nitric Oxide ◽  
Gas Phase ◽  
Marked Effect ◽  
Volume Ratio ◽  
Oxidation Of Methanol ◽  
Inorganic Substances ◽  
Phase Oxidation ◽  
Gas Phase Oxidation ◽  
Kinetics Of ◽  
Effect Of Surface

A study has been made of the effect of the surface-to-volume ratio of the reaction vessel and of coatings of various inorganic substances on the vessel walls on the gas-phase oxidation of methanol catalysed by nitric oxide. The results show that, whereas packing the vessel does not have a marked effect on the rate, the kinetics of the reaction are profoundly influenced by the nature of the surface. The results suggest that the methanol-oxidation chains are initiated at the surface by reaction between methanol and nitrogen dioxide, and that HO2 radicals play an important role in the subsequent chain reaction.

Kinetics of Pd/alumina catalysed 1,2-dichloroethane gas-phase oxidation

2006 ◽  
Vol 61 (11) ◽  
pp. 3564-3576 ◽  
Author(s):  
A. Aranzabal ◽  
J.A. González-Marcos ◽  
J.L. Ayastuy ◽  
J.R. González-Velasco
Keyword(s):  
Gas Phase ◽  
Phase Oxidation ◽  
Gas Phase Oxidation ◽  
Kinetics Of

Mononuclear metavanadate catalyses gas phase oxidation of methanol to formaldehyde employing dioxygen as the terminal oxidant

2006 ◽  
pp. 4503 ◽  
Author(s):  
Tom Waters ◽  
George N. Khairallah ◽  
Samantha A. S. Y. Wimala ◽  
Yien C. Ang ◽  
Richard A. J. O'Hair ◽  
...  
Keyword(s):  
Gas Phase ◽  
Oxidation Of Methanol ◽  
Phase Oxidation ◽  
Gas Phase Oxidation

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.

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