Production of COx-free hydrogen by the thermal decomposition of methane over activated carbon: Catalyst deactivation

Hydrogen, an environment-friendly energy source, is deemed to become strongly in demand over the next decades. In this work, CO_x-free hydrogen was produced by the thermal catalytic decomposition (TCD) of methane by a carbon catalyst. Deactivated catalysts at four-stage of progressive were characterized by nitrogen sorption and scanning electron microscopy. TCD of methane at 820 and 940 °C was about 13- and 8-folds higher than non-catalytic decomposition, respectively. High temperatures positively affected the kinetics of hydrogen production but negatively influenced the total amount of hydrogen and carbon products. The total pore volume was a good indicator of the total amount of hydrogen product. Catalyst activity was decreased because of the changes in the catalyst's textural properties within three ranges of relative time, that is, 0 to 45, 0.45 to 0.65, and 0.65 to 1. Models for specific surface area and total pore volume as functions of catalyst deactivation kinetics were developed.