The results obtained in the Titan project after 18 months show that direct biogas conversion in a fluidised catalytic reactor heated by MW and using iron as cheap, non-toxic and abundant metal catalyst can produce a syngas of suitable composition for methanol synthesis or for liquid hydrocarbons production via the Fisher-Tropsch process. Confirmed by a thermodynamic analysis, the reaction proceeds at temperatures above 900°C to produce carbon materials, whereas at lower temperatures the carbon is converted to CO by the Boudouard reaction. At 950°C, very high methane and CO2 conversions are achieved (>90% and 99%, respectively), accompanied by high hydrogen yield (>90%) and the sequestration of carbon with a turbostratic structure.
TITAN technical results indicate that the direct catalytic reforming of biogas in a fluidised bed, when combined in series with an FTS process, could allow the production of liquid fuels with no need for costly gas separation units, in particular those implemented for CO2 capture.
The results obtained in the TITAN project after 36 months demonstrate that direct biogas conversion in a MW-heated fluidised catalytic reactor using iron as a cheap, non-toxic, and abundant catalyst can produce either hydrogen at a competitive cost—suitable for large-scale, decarbonized H2 production—or a syngas of appropriate composition for liquid hydrocarbon synthesis via the Fischer–Tropsch process, suitable for small-scale farm installations.
Catalytic pyrolysis at high temperatures (900–950 °C) generated a graphite-type shell on the iron particles. Although the catalysts can be regenerated up to five times using CO2 without any loss of activity, this graphite shell remains permanently attached to the catalyst. In the techno-economic analysis, the catalyst is therefore considered a consumable, with the end product (Fe/C) valued at the same cost as the fresh catalyst (Fe).
The spent catalyst presents no toxicity when released into the soil. The carbon component is not rapidly mineralized into CO2 and may even improve certain soil types by enhancing their capacity to capture heavy metals.
The main limitation lies in the current valuation of “turquoise hydrogen,” a negative-emission technology that is not yet fully recognized. Although its CO2 footprint is negative, its market value is, at best, treated as neutral.
