Particle and gas combustion in catalytic systems

Kinetic data on soot and pyrolytic graphite oxidation rates have been used to calculate the ability of woodstove catalysts to burn woodstove effluent particles. Large variations appear in the literature and depending upon which particle diameter and rates were used one can calculate maximum possible particle oxidation efficiencies of 10⁻¹ to 40 per cent, with most investigators predicting less than a 1 per cent efficiency. This suggests that the 80 per cent reduction in "particulate" emissions which is shown by tests with catalyst-equipped stoves is due to catalytic oxidation of high molecular weight vapors rather than due to particle burnup. Dilute (500 and 250 ppm) acetylene/air mixtures flowing between parallel catalytic plates have been studied experimentally. Measured acetylene profiles for the hydrodynamic entry length region are presented and compared to profiles calculated by a single-phase, two-dimensional, low mass transfer analytical model currently under development and which eventually will be extended to cover three-dimensional flows such as those in the passageways of a woodstove catalyst. The measured temperature profile for a 5000 ppm acetylene/air mixture flowing between parallel catalytic plates was compared to the temperature profile calculated by a single step, adiabatic, constant pressure, homogeneous model.