Methane pyrolysis in a molten gallium bubble column reactor for sustainable hydrogen production: Proof of concept & techno-economic assessment

Nowadays, nearly 50% of the hydrogen produced worldwide comes from Steam Methane Reforming (SMR) at an environmental burden of 10.5 tCO2,eq/tH2, accelerating the conse- quences of global warming. One way to produce clean hydrogen is via methane pyrolysis using melts of metals and salts. Compared to SMR, significant less CO2 is produced due to conversion of methane into hydrogen and carbon, making this route more sustainable to generatehydrogen.Hydrogenisproducedwithhighpurity,andsolidcarbonissegregatedand deposited on the molten bath. Carbon may be sold as valuable co-product, making industrial scale promising. In this work, methane pyrolysis was performed in a quartz bubble column using moltengallium as heat transfer agent and catalyst. Amaximumconversion of91%was achieved at 1119 ?Candambient pressure, witharesidence timeofthe bubbles in the liquid of 0.5 s. Based on in-depth analysis of the carbon, it can be characterized as carbon black. Techno-economic and sensitivity analyses of the industrial concept were done for different scenarios.Theresultsshowedthat, ifco-productcarbonissaleableandaCO2taxof50europer tonne is imposedtotheprocesses, themoltenmetaltechnologycanbecompetitivewithSMR.