Review of methane cracking over carbon-based catalyst for energy and fuels

Catalytic decomposition of methane is today considered as a pathway to hydrogen production that - unlike the other well-known methods - can convert methane into hydrogen without generating COx emission, but rather delivering solid Carbon, a storable and useable product which, in case of biomethane cracking, generates biogenic Carbon and a Carbon Negative route (Negative Emission Technology). Although mostly metallic catalysts have been used for this purpose, due to the rapid deactivation of this type of catalyst and the challenges of their regeneration, methane decomposition over carbon materials attracted some attention during recent years. This work provides a review of the recent studies performed on hydrogen production through methane cracking over carbon-based catalyst. The impact of operating parameters such as reaction temperature, pressure, feedstock purity, space velocity as well as the catalyst characteristics including particle size, surface area, pore volume, oxygenated compounds, and ash content on methane decomposition has been widely discussed in this review. Based on the literatures, operating temperature more than 800 ◦C and space velocity less than 1 L/g.h for pure methane are required to provide methane conversion higher than 50%. Also, reducing the concentration of methane in feedstock with inert gases as well as using carbon-based catalysts with lower particle size, higher surface area, more mesopores and oxygenated compounds can reach to an enhancement in methane conversion. Also, investigation on impact of ash content shows loading metals such as Fe, Ni, Ca, and Pd metals over carbonaceous materials improve their catalytic activities.