Optimization of the lifetime of CeO2-carrier material over consecutive conversion cycles of methane for hydrogen and syngas production

Despite all efforts to mitigate climate change, new energy sources cannot replace fossil fuels on a large scale at the short term and the supply of energy and fine chemicals must be addressed with the smart utilization of resources most largely available. The US energy information administration reports that there are abundant natural gas and shale gas reserves in the world and most of them are recoverable [1], as a consequence processes involving methane conversion are worthy to be investigated and optimized. Traditional processes involving methane utilization suffer severe carbon deposition and sintering of the active phase, especially when CO2 is present as co-reagent. Moreover, the majority of such processes relies on the use of expensive catalytic materials where the active phase is often a noble metal with high cost of raw material and also greater cost associated to the disposal of the exhausted catalyst. In the past years the utilization of CeO2, a rare earth mineral, for reforming processes has constantly increased due to its remarkable redox properties and its resistance in harsh environments, including temperatures up to 2000 °C [2]. Furthermore, cerium, despite being a lanthanide, is rather abundant in the earth's crust, comparable to copper [3]. However, its use poses kinetic limits of the reforming reaction that requires temperature around 900-950°C [4] to achieve appreciable yields of syngas.