Methane Pyrolysis Using a Multiphase Molten Metal Reactor

Methane pyrolysis is a unique approach toward generatinghydrogenand valuable carbon products, with the added advantage of low to near-zeroCO(2) emissions. Currently, the most popular method for hydrogenproduction is steam methane reforming, which generates more than 10kg of CO2 for every 1 kg of hydrogen. By comparison, methanepyrolysis produces hydrogen and solid carbon with no CO x biproduct. Methane pyrolysis on a conventional solid catalyst exhibits low activation energy, but the carbon coproductcannot be separated and rapidly poisons the surface (coking). On theother hand, molten liquid metal catalysts have been shown to havethe advantage of separatable carbon, but their high activation energylimits the rate of the reaction and potential for economic industrialization.In this work, methane pyrolysis was shown using a multiphase moltenmetal reactor where both liquid and solid metal alloy catalysts were in equilibrium. Catalytic measurements using a Sn-Ni meltshowed that operating the reactor in the two-phase region of the Sn-Niphase diagram decreased the apparent activation energy from 355 kJ/molin the liquid-only melt to 158 kJ/mol, all while maintaining the abilityto separate and recover graphitic carbon.