Hydrogen-enriched natural gas in a decarbonization perspective

Natural gas is a major fuel source for power generation and heating applications. To partly decarbonize its use, a promising technology is the production of hydrogen, easy to be mixed into the natural gas grid, or directly used in fuel cells and industrial kilns. The thermo-catalytic decomposition of CH4 into H-2 and C is gaining interest. The produced carbon black can moreover be sold as a filler. Over the past decades, several catalysts for the CH4 decomposition systems have been proposed, i.e. graphite/charcoal, metal-doped carbon catalysts, molten metals, metallic nickel, and molten Ni-Bi alloy. All these catalysts are expensive because of the constituent compounds, and have rather low decompositions efficiencies. To counteract these shortcomings, the present research investigates the use of cheaper, readily fabricated and efficient catalysts. Experiments using both a Fe/Al2O3 and Ni/MgO catalyst were performed. The Fe/Al2O3 catalyst with 20 wt% Fe-loading, can provide an 80% methane conversion at a temperature of 800 degrees C, whereas the Ni/MgO catalyst is less effective at the same temperature and residence time. The carbon formed by the CH4 decomposition accumulates within the catalyst with a progressive reduction in H-2 yield. A periodic regeneration is required. Kinetic expressions were developed and used in designing a pilot-scale reactor. A twin decomposition/regeneration fluidized bed was developed. The economy of the system is promising, with low CO2 emission and H-2 costs per kg around 1 (sic)/kg, hence competitive with the current steam reforming of methane.

Automated summary

Natural gas, being a major fuel source, is being researched for its potential to be partially decarbonized through the production of hydrogen. The thermo-catalytic decomposition of CH4 into H-2 and C is gaining interest as a promising technology. Cheaper and more efficient catalysts are being investigated for this process.