A system for hydrocarbon decomposition comprising a reactor volume, a mechanism to distribute the liquid catalyst as a liquid mist, a distributor to distribute a hydrocarbon reactant, a heat source, a separator to separate the solid product from the liquid catalyst, a re-circulation path and mechanism to re-circulate the liquid catalyst, and an outlet for at least one gaseous product. A system to distribute a liquid to an enclosed volume as a mist has a plurality of orifices designed to break the liquid into a mist. A method to decompose a hydrocarbon reactant includes generating a mist of a liquid catalyst, heating the reactor volume, introducing a hydrocarbon reactant into the reactor volume to produce a solid product and a gaseous product, separating the solid product from the liquid catalyst, removing the solid and gaseous products from the reactor volume, and recirculating the liquid catalyst to the reactor volume.