Hydrogen production by thermocatalytic decomposition of methane using a fixed bed activated carbon in a pilot scale unit: Apparent kinetic, deactivation and diffusional limitation studies

Thermocatalytic decomposition (TCD) of methane is a promising method to produce hydrogen. A series of experiments was conducted to study the apparent kinetic, catalyst deactivation and effect of mass diffusion for methane TCD to produce hydrogen using palm-shell carbon based activated carbon (ACPS) as a catalyst in a fixed bed reactor. The experiment was carried out under atmospheric pressure at 775–850 °C, and different methane residence times calculated based on changing the ACPS weight at a constant methane flow rate or changing the methane flow rate at a constant ACPS weight. A reaction order as found substantially differs from that found in literature. A deactivation order of 0.5 and deactivation energy of 177 KJ mol−1 is obtained and the results fitted well with a simple developed model. Mass diffusion transfers are accounted for by calculating change of Weisz modulus with time on-stream using different weights of ACPS or different flow rates of methane. The result showed that Weisz modulus decrease with time and it is attributed to the deposition of carbon produced from methane decomposition. Surface properties measurements of the virgin and deactivated ACPSs indicated that methane decomposition occurs mainly within AC micropores.