The chemical processing of binary mixtures of
benzene and acetylene with ammonia or carbon monoxide has been
studied in the continuous flow microwave discharge reactor at
2450 MHz. The microwave discharge was modelled as a
CSTR reactor, and the volume was assumed to be proportional to the
power absorbed. Reynolds numbers in the lamina region were
calculated for the gas flows in the silica reactor tube.
The operating variables investigated were
reactant ratios, reactor pressures, the effect of nickel in the
discharge zone, flowrate through the reactor and the power absorption.
Two microwave cavities were used.
No reaction occurred in either of the carbon
monoxide binary systems. The prime product of the reaction between
benzene or acetylene with ammonia was hydrogen cyanide. No reaction
or decomposition occurred below a critical mole ratio.in either
system. Hydrogen and nitrogen were also formed on reaction in both
systems together with small quantities of polymer. Acetylene,
butadiene and aniline were also formed in the benzene/ammonia system.
No azo-benzenes were produced. The selectivity of the hydrogen cyanide
formation was ~ 90% in the acetylene/ammonia system and ~ 50% in the
benzene/ammonia system. The maximum yield of hydrogen cyanide was
·27.5 gm/kW.h in the acetylene/ammonia system and 35.0 gm/kW.h in the
benzene/ammonia system. The rate of production of hydrogen cyanide
was found to have an order of 1.5 with respect to the acetylene and uammonia
in the acetylene/ammonia system in one set of experimental
runs and was zero order with respect to the benzene and ammonia in
the benzene/ammonia system, The values of the rate constants were
dependent upon the cavity and the power absorbed.
Comparison with other discharge processes
indicates that increased frequency increases the production of hydrogen cyanide.
In conclusion it was proposed that as the
difference in ionization potential between the two compounds in the
binary mixture increases it becomes progressively more difficult for
reactive species to be produced in the microwave discharge, This
was thought likely to be due to a change in the electron energy
distribution in the microwave discharge .
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.