Poster de conférence
Résumé : The important development of biogas plants requires the use of high performance new sensors to analyze the composition of the gas produced. They must be able to combine rapidity, reliability, and precision with an easy and inexpensive utilization. Such a sensor does not currently exist. Sensors based on the detection of a catalytically induced reaction are what seems to be the most promising possibility. There are a large number of active phases currently under study. This work focuses on cobalt systems. The active phases that we studied were made by the decomposition of cobalt oxalate in Ar, Ar/H2 or Ar/O2, giving us respectively a mix of CoO/Co, metallic Co or Co3O4. The active phase was then put in a flow of methane or carbon dioxide, and the evolution of the composition of the flow was studied by MS measurements. If any change in the composition is observed, it is a proof that an interaction occurs between the active phase and the target gases. CoO/Co and Co3O4 demonstrate such changes, proving that they are able to interact with the gases. They can even be reduced by methane, yielding carbon dioxide. Such a reaction could be the sign that the oxidation of methane on cobalt based catalyst follows a Mars-van Krevelen mechanism. However, we are still facing two difficulties: temperatures needed to evidence a reaction with methane can be quite high, and a good way to place the active phase on a micro-chip sensor is still needed.