The oxides of chromium, magnesium, manganese, cobalt and iron in single or in binary mixtures were used for the catalytic combustion of propane/air in an adiabatic tubular reactor. Each of the catalysts was deposited on an alumina coated honeycomb ceramic substrate. The effect of inlet temperature and equivalence ratio on the combustion efficiency, temperature and emission levels were investigated. Among the catalysts examined, the most suitable was the binary mixture of cobalt oxide and chromium oxide. Complete combustion started at an equivalence ratio of 0.196 and an inlet temperature of 580#xB0;K. The residence time was 19 ms and the NOxemission index for these conditions was 0.03 g/kg fuel. Chromium oxide alone gives a maximum of 89 percent conversion at inlet temperatures slightly higher than those used with cobalt oxide-chromium oxide catalysts.
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