H2 production by methane decomposition: catalytic and technological aspect

Ni and Co supported on SiO2 and Al2O3 silica cloth thin layer catalysts have been investigated in the catalytic decomposition of natural gas reaction. The influence of carrier nature and reaction temperature was evaluated with the aim to individuate the key factors affecting coke formation. Both Ni and Co silica supported catalysts, due to the low metal support interaction (MSI), promote the formation of carbon filament with particles at tip. On the contrary, in case alumina was used as support, metals strongly interact with surface depressing both metal sintering and particles detachment from catalyst surface. In such cases, carbon grows on metal particle with a base mechanism while particles remain well anchored on the catalyst surface. This allowed to realize a cyclic dual-step process based on CH4 decomposition and catalyst oxygen regeneration without catalysts deactivation. Technological considerations led to conclude that the implement of a process based on decomposition and regeneration of catalyst by oxidation requires the development of a robust catalytic system characterized by both a strong MSI and a well defined particle size distribution. The catalyst should be able to operate at high temperature, necessary to reach high methane conversion values avoiding the formation of the carbon filaments with metal at tip or the encapsulating carbon which drastically deactivate the catalyst.