Effect of air pre-oxidization on coal-based activated carbon for methane decomposition to hydrogen

Oxidization is considered to be an indispensable step for coals with thermoplastic properties to act as the precursor of activated carbon (AC). In this work, the effect of oxidization conditions of coal on the texture and surface properties of resultant ACs and their catalytic performances in decomposition of methane to hydrogen were investigated. The results show that the surface oxygen containing groups of the resultant ACs changed, the surface area of ACs increases from 1892 m2/g to 2407 m2/g, and the mesoporosity significantly increases after the precursor coal is pre-oxidized. The ACs from oxidized coals show higher catalytic activities in methane decomposition reaction than that from raw coal. The ACs prepared from oxidized coal at 373 K show the best stability while the AC from the oxidized coal at 573 K for 4 h exhibits the highest initial activity among the ACs. Additionally, the oxidization time has a negative effect on initial activities but little positive influence on stability of ACs when the precursor is oxidized at 373 K. It is thought that the increased mesoporosity is beneficial to the catalytic activity and stability of AC in methane decomposition to hydrogen.