Thermo catalytic decomposition of methane over Ni-Mg and Ni-Cu-Mg catalysts Effect of catalyst preparation method

摘要

Catalytic decomposition of methane is a potential alternative route for the production of hydrogen from natural gas.In the present paper we report the results of hydrogen productionin the TCD of methane over Ni-Mg and Ni-Cu-Mg catalysts prepared by co-precipitation,impregnation and fusion methods.The characterization of the catalysts used and the carbon obtained is also presented.Whatever to be the preparation method,all the catalysts show a high and almost constant methane decomposition rate without deactivation after 8 h on stream.The presence of copper enhances hydrogen production and the best results were obtained for Ni-Cu-Mg catalysts prepared by the fusion method,reaching a hydrogen production of 80 vol.%.For the Ni-Mg catalysts,the nickel crystal size influences on the catalysts performance so that the highest the crystallite size the lowest the hydrogen yields.In contrast,for the Ni-Cu-Mg catalyst the Ni particle size has not a significant influence on the hydrogen yields.All catalysts tested promote formation of filamentous carbon some micrometers long and with a fiber diameter highly dependent on the presence of Cu:Ni-Mg catalysts promote the formation of fibers with homogeneous diameter around 30 nm while Ni-Cu-Mg catalysts lead to the formation of fibers of inhomogeneous and bigger diameter.