EFFECT OF CARBON-MONOXIDE ON NITRIC-OXIDE IN EXHAUST-GASES

The conversion of nitric oxide (NO) to nitrogen dioxide (NO2) was observed in a laminar-flow, quartz reactor for a lean mixture of oxygen, water, carbon monoxide and nitrogen for temperatures between 800 and 1000 K. This conversion is accurately predicted by a newly modified model of the nitric oxide exhaust gas chemistry. The quantitative level of this conversion is dependent on the gas temperature, and on the concentrations of oxygen, water and carbon monoxide. For example, for one set of gases (1260 ppm carbon monoxide, 12.3% oxygen, 2% water and 330 ppm nitric oxide), 25% of the original nitric oxide was converted to nitrogen dioxide at 820 K. Increasing the inlet concentrations of oxygen, water or carbon monoxide increased this effect for the conditions examined.