CO x Free Hydrogen Production by Catalytic Decomposition of Methane Over Porous Ni/Al2O3 Catalysts

The prepared mesoporous spherical alumina with high-surface area was employed as a support for nickel catalysts in methane decomposition reaction. It was observed that, the catalytic activity of Ni/Al2O3 catalysts was high at the initial times of reaction and decreased with time on stream, and finally reached a constant value. The deactivation rate of catalysts is dependent on the catalyst characteristics and the operating conditions. The activity results indicate that, the yield of hydrogen and the structure of deposited carbon are strongly dependent on the loading amount of Ni. The SEM results showed that carbon formed on the catalysts in the form of filamentous carbon. Concerning hydrogen production, the 10%Ni/ Al2O3 catalyst leads to a higher yield, due to the higher amount of active phases which can catalyze further the number of methane molecules, while lesser amounts of filamentous carbon were observed on this catalyst than for 5 and 7.5%Ni/ Al2O3 catalysts at the same operating condition. The yield of hydrogen and structure of filamentous carbon also significantly depend on the reaction temperatures and residence time of gas in the reactor, as the 10%Ni/ Al2O3 catalyst showed a remarkable stability with a decrease of about 14% at 800 °C and 25 ml/min after 240 min of reaction. The obtained results showed that the prepared Ni/ Al2O3 catalysts had a good activity in methane decomposition reaction, which is one of the highest activities among those for low nickel loaded catalysts reported up until now