Catalytic combustion of methane and n-butane with Pt/ZSM-5 in a microtube was studied on self-sustaining combustion limits

product concentrations

wall temperature

and surface heat loss. The catalytic combustion of methane and n-butane could be sustained at very high molar ratio (Φ) in rich burn condition. At the same flow rate

n-butane had broader self-sustaining combustion limit than methane with lean burn limit around 0.4. Conversion of the two fuels decreased steeply with flow rate increased from 200 to 1000 ml·min-1

which were largely due to decrease of residence time and increase of weight hourly space velocity (WHSV). The combustion conversion of methane and n-butane showed minimal difference within the range of experiments. As a result of activation of gas-phase reactions posterior to catalyst and its feedback effect to catalytic reaction

n-butane had higher conversion than methane at the same chemical normality upon flow rate reaching to 600 ml·min-1. Both methane and n-butane could have self-sustaining combustion with above 95% conversion even when ratio of through-wall heat loss to input power was reached to 70%. Compared to that of methane

n-butane combustion produced higher wall temperature

through-wall heat loss rate

and ratio of through-wall heat loss rate to input power

which was directly related to the activation of gas-phase reactions in n-butane combustion. Overall

considered broader combustion limit

similar conversion curve

minimal difference in heat generate rate and through-wall heat loss

n-butane could be an alternative fuel to methane when necessary.