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.
Electrochemical gas phase oxidation of hydrogen chloride to chlorine: Model-based analysis of transport and reaction mechanisms
