(526d) Hydrogen Production from Methane Cracking in a Fluidized Bed Process

Hydrogen is widely considered as a major future carbon-free energy carrier that can be utilized for power generation, heating and as a transportation fuel. However, hydrogen is currently produced almost exclusively from fossil hydrocarbons, with the dominant production route being the steam-methane reforming (SMR) of natural gas.

CH₄ + H₂O → CO + 3H₂ΔH_r=206 kJ (1)

This process inevitably produces CO₂ emissions to the atmosphere and will thus contribute to global warming. Alternatively, hydrogen can be produced by water/steam electrolysis driven by renewable energy; however this process is currently still burdened with high capital costs and not deployed at a large-enough scale. As a bridging technology hydrogen could be produced from methane via cracking on a suitable substrate.

CH₄ → C + 2H₂ΔH_r=74.6 kJ (2)

This process binds carbon in solid form and thus does not directly release CO₂ to the atmosphere. This advantage could potentially outweigh the drawback of not being able to utilize the entire calorific value of methane (c.f. LHV(CH₄)= 802 kJ and 2*LHV( H₂)=488 kJ). Here, we explore the cracking of methane into solid carbon and hydrogen in a laboratory-scale fluidized bed reactor over different supported metal substrates. Produced gases were analyzed by on-line ND-IR measurement and materials characterized by X-ray diffraction and SEM imaging at different stages of the process. For each substrate material, we discuss gas conversions, selectivity, obtained carbon structures and strategies for regeneration of / carbon recovery from the substrate. Based on the results, the on-going development of a chemical-looping based approach for this process will be presented.