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

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 production in 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.

In this paper we study the performance of Ni–Mg catalysts on hydrogen production by TCD of methane prepared by three different methods: co-precipitation, impregnation and fusion. The effect of Cu doping has also been analyzed. Catalysts and deposited carbon have been characterized by ICP-OES, XRD, SEM, TEM and Raman spectroscopy. Deposited carbon appears as fishbone type nanofibers. Figure optionsDownload as PowerPoint slide