Reaction and Deactivation Rates of Methane Catalytic Cracking over Nickel

The kinetics of methane catalytic cracking over nickel supported on porous and nonporous aluminas was modeled using a separable kinetics approach in order to develop initial rate and activity decay equations. The model parameters were estimated using a set of experiments conducted in an electrobalance. The experimental work covered the 500–650 °C temperature range, using pure methane, as well as different partial pressures of CH₄/N₂ and CH₄/H₂ mixtures at atmospheric pressure. The model results showed a good match with the experimental data, and the estimated kinetic parameters agreed well with those reported in the literature. The morphology of the support affected the initial reaction rate and catalyst deactivation. The methane cracking activation energy was estimated to be 88 and 75 kJ/mol for the porous and nonporous catalysts, respectively. The activation energy for the encapsulating carbon formation was estimated to be 147 and 149 kJ/mol for the porous and nonporous catalysts, respectively. The deactivation reaction was found to be half-order in surface carbon. The model was expanded to include cracking/regeneration cycles. The model showed good agreement with the experimental data at different experimental conditions and up to 39 cycles. Cracking/regeneration cycles suggest that the porous catalyst can be used for conducting continuous methane cracking