Formation and Reduction of Carbon Monoxide

The total amounts of carbon monoxide (CO) and carbon dioxide (CO2) in the mainstream smoke of a burning cigarette during a steady draw were measured by a non-dispersive infrared (IR) technique for a variety of flow rates. The temperature profiles in the cigarette were also measured under the same flow conditions. The data were used in a diffusion model to estimate the concentrations of these gases downstream of the pyrolysis zone. The contribution of pyrolysis in the generation of these gases was calculated using a kinetic model. The remaining CO and CO2 are attributed to processes occurring in the combustion zone. The calculated mean concentrations of carbon oxides behind the pyrolysis zone are in reasonable agreement with the experimental data. The contributions of pyrolysis and combustion to the formation of CO were found to be approximately 1/3 and 2/3 respectively. The results show that the peak temperature rises with an increase in the mainstream flow rate in the limited range of 0 to 200 mL/min. As a result, the concentrations of carbon oxides behind the pyrolysis zone also increase with the flow rate and reach plateaus at higher flow rates.