A new system for plasma-driven catalytic dry reforming of methane

Among the possibilities for syngas production, CO2 reforming of methane is very attractive (CH4 + CO2 => 2 CO + 2 H2). The environmental importance of this process consists in the possibility of recycling CH4 and CO2, which are the two major greenhouse gases, in a process useful for industry. Syngas can be stocked, transported and/or converted in hydrocarbons or in valuable oxygenated compounds. Unfortunately, dry reforming is a highly endothermic reaction, which requires a high operating temperature and the use of a catalyst [1]. Moreover, the occurrence of the Boudouard reaction (2 CO => CO2 + C) and methane cracking (CH4 => C + 2 H2) as side reactions induces carbon deposition which deactivates the catalyst. To overcome these problems, activation of dry reforming by the combination of an heterogeneous catalyst with non-thermal plasma has been recently proposed in the literature. When the catalyst is placed in the discharge zone, the results in most cases demonstrate the occurrence of a synergy between plasma and heterogeneous catalysis which allows to work at lower temperatures and decrease coke deposition. [2,3]. We report here the development of a prototype reactor for CO2 reforming of methane based on the application of corona discharges above the surface of a catalyst. The system has been designed to perform activity trials with and without plasma and with and without an heterogeneous catalyst. The catalyst can be introduced as a powder or in grains and is placed directly into the discharge zone. It is also possible to vary the distance between the active electrode and the catalyst to optimize the synergy between plasma and catalyst. The reactor was designed in such a way that it can be operated at temperatures up to 800°C, necessary for a purely catalytic process, without suffering any damage to the electrodes due to thermal expansion. The first tests will be carried out without the heterogeneous catalyst, so as to study the process induced by plasma alone. Plasma will be produced by different types of discharges in order to find and optimize the best power supply to be used in the combined experiments. Analogously, the process induced by innovative Ni- and noble metal-based catalysts supported on nanostructured ceria and zirconia or perovskites will be studied in the absence of plasma. The preliminary results obtained will be used to optimize the experimental conditions for the study of the effects of the combination of catalyst and plasma. Particular attention will be devoted to the study of the mechanism of the synergy between plasma and catalyst.