A review of methane pyrolysis technologies for hydrogen production

Clean hydrogen can help mitigate greenhouse gas (GHG) emissions while accommodating the projected increase in global energy demand. Methane pyrolysis is a technology that can produce low-cost, low-emission hydrogenIn the absence of oxygen, this process can use endothermic reactions that split C–H bonds to produce gaseous hydrogen and solid carbon. Thermodynamically, methane pyrolysis produces a lower amount of GHG emissions compared to steam methane reforming (SMR)and it requires high temperatures (800–1600 °C) to overcome activation energy barriers. The methods used to overcome operational challenges, while improving thermal efficiency, include using solid catalysts, molten metals and molten salts. This study evaluates recent developments in methane pyrolysis technologies, including their advantages, limitations, and development status. Specifically, alternative energy transfer methods (e.g., microwave, plasma, induction, shockwave, radiation heating), reactor designs (e.g., bubble column, plug, fluidized-bed, packed-bed, pulse tube, tubular, fluid wall, honeycomb monolith and moving carbon-bed) and combinations of two or more technologies are analyzed and compared. This work discusses the commercialization challenges to achieve high-purity hydrogen and solid carbon with facile separation methods. The analysis indicates that the most prominent barriers to methane pyrolysis are trelated to the challenges under high-temperature and high-pressure operation, as well as corrosive reaction environments. These challenges will require additional research and investment in reactor design and fabrication solutions. .