(477e) Economic Comparison of Methane Pyrolysis Processes for Hydrogen Production Based on Various Molten-Metal Catalysts

Interests in clean energy sources are increasing to simultaneously pursue carbon neutrality and energy supply. Hydrogen, a clean energy source, does not emit greenhouse gases such as carbon dioxide during combustion and generates only water and heat. Hydrogen is categorized into gray, blue, green, and turquoise hydrogen, depending on the production technology and carbon dioxide emissions. Turquoise H₂ technology, which produces hydrogen and solid carbon from methane, has the advantage of less energy to produce hydrogen compared to water electrolysis and less CO₂ emissions. The methane pyrolysis without catalyst requires endothermical energy above 1300 °C. Solid metal-based, carbon-based, and molten-metal (MM) based catalysts have been used to reduce the reaction temperature. The buble column reactors (BCRs) with MM catalysts offer high mass and heat transfer efficiency. Various MM catalysts were reported to decrease the operating temperature and increase the methane conversion.

In this study, a one-dimensional (1D) MMBCR model was used to calculate the CH₄ conversion in the BCRs with MM catalysts such as tin, gallium, copper, Ni₂₇-Bi₇₃, tellurium for CH₄ pyrolysis. The process flow diagrams (PFDs) with carbon separation were presented for a hydrogen production capacity of 200 kt/yr. Economic indicators such as hydrogen production cost, total capital investment (TCI), and total production cost (TPC) were compared for the H₂ production processes using different molten-metals. The effects of the methane conversion and economic values on MM catalysts were analyzed.