Development of Ni-Al Catalysts for Hydrogen and Carbon Nanofibre Production by Catalytic Decomposition of Methane.Effect of MgO Addition

摘要

Catalytic decomposition of methane is a potential alternative route for the production of hydrogen and nanocarbonaceous materials from natural gas and other hydrocarbon feedstocks.In the present paper,we report the results of characterization and catalytic behaviour during the methane decomposition reaction of a spinel-like Ni-Mg-Al catalyst prepared by coprecipitation.The influence of reaction temperature and feed composition on carbon content,carbon formation rate and carbon morphology has also been studied.The main consequence of MgO addition to the support is the increase in the activity and stability of the Ni-Al catalysts.The better performance of Ni-Mg-Al catalysts is due to the higher interaction generated between Ni particles and the support in this catalyst,which prevents the formation of large metallic particles.The carbonaceous products are carbon nanofibres(diameters ~ 10-35 nm)and amorphous carbon,which causes the catalyst deactivation by encapsulation.The amount of each type of carbonaceous material depends on the different operating conditions used.The reduction-reaction-regeneration cycles lead to a remarkable sintering of the Ni crystallites due to weakening of the metal-support interaction.