Deactivation of palm shell-based activated carbon catalyst used for hydrogen production by thermocatalytic decomposition of methane

摘要

Thermocatalytic decomposition of methane over activated carbon acting as a catalyst is proposed as a potential alternative for hydrogen production. However, over a certain duration catalyst becomes deactivated due to intensive carbon deposition. The main research objective is to study the catalyst deactivation kinetic and modeling of the mass gain due to carbon deposition with time. The catalyst activity was found to decrease almost linearly with the amount of carbon deposited at 800 ℃, while at higher temperature the diffusion effect appeared to occur significantly, especially at the end of the process. A novel model has been developed to describe the decrease of catalyst activity with time. A deactivation order of 0.5 and deactivation energy of 194 KJ mol~(-1) were obtained and the mass gain fitted well with the model results based on Voorhies equation which is commonly used for reaction that involves hydrocarbon cracking. Comparison between activated carbon (AC) from palm shell carbon-based and commercial based AC shows almost similar deactivation kinetic and validity of Voorhies correlation.