Effects of radical desorption on catalyst activity and coke formation during the catalytic pyrolysis and oxidation of light alkanes Original Research Article

Catalytic pyrolysis and partial oxidation of methane and liquefied petroleum gas (LPG) were studied using a novel wire-mesh reactor (WMR) and a quartz tubular reactor. A non-porous nickel mesh was used as a catalyst to avoid the complexity of internal pore diffusion. The catalyst activities were stable even for the pyrolysis of pure methane and LPG when short gas–catalyst contact times were used. The desorption of radicals from the mesh catalyst surface into the gas phase at short gas–catalyst contact time was an important process for the radicals, competing well even with the oxidation of these radicals by oxygen on the catalyst surface. The desorption of radicals plays an important role for the formation of reaction products, e.g. ethane from the pyrolysis and oxidation of methane. Scanning electron microscope (SEM) images and EDX analysis of the used mesh catalyst indicate that the desorption of radicals greatly limits the successive dehydrogenation of radicals on the catalyst surface and therefore greatly limits or eliminates the formation of coke on the surface of non-porous mesh catalyst. Our results have implications for the understanding of coke formation in a porous pellet catalyst.