甲烷与正丁烷微小尺度催化燃烧性能比较

对微圆管内甲烷和正丁烷在Pt/ZSM-5上的催化燃烧进行实验研究，获得并分析了二者的稳燃范围、产物浓度、壁温分布和壁面散热等燃烧性能。发现在富燃条件下甲烷和正丁烷能够在大当量比下实现催化自稳燃烧。相同流量下正丁烷稳燃当量比范围宽于甲烷，贫燃范围在0.4附近。流量由200 ml·min^-1增大至1000 ml·min^-1，甲烷和正丁烷转化率出现大幅下降。在实验范围内，正丁烷和甲烷的转化率差异不大。化学当量比条件下随流量增大，正丁烷的转化率在600 ml·min^-1开始高于甲烷。甲烷和正丁烷能够在散热比例高达70%的情况下自稳催化燃烧且转化率在95%以上。相同流量下，与甲烷相比，正丁烷催化燃烧的壁温、散热功率和散热比例都更高。整体来看，正丁烷催化稳燃范围较甲烷略宽，两者转化率曲线相近，放热功率和壁面散热功率相差较小，正丁烷在必要时可作为甲烷的替代燃料。

Comparison of catalytic combustion of methane and n-butane in microtube

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.