Catalytic oxidation of methane on platinum thin films
Résumé
The kinetics of methane catalytic oxidation on platinum thin films have been studied in order to improve the lifetime and sensitivity of methane calorimetric sensors. The samples are placed in a quartz reactor and are heated up to 830 °C in isothermal conditions under a mixture of 1% methane in air with a flow rate of a few tens of cm-^/min. The gas phase is analysed by mass spectrometry. The behaviour of thin platinum ribbons and of evaporated thin films has been compared. An Arrhenius plot of the reaction rate yields an activation energy of about 30-35 kcal/ mole for platinum ribbons, which is consistent with previous determinations. After heating the obtained platinum films at a temperature higher than 730 °C in the reactive mixture, their activity becomes of the same order of magnitude as that of clean platinum ribbons.