Global warming concerns have motivated the study of new approaches that can decarbonize fossil fuels to produce clean fuels and commodities. A promising approach is solar-thermal methane pyrolysis to convert natural gas into clean hydrogen fuel and high-quality carbon product with virtually zero CO2 emissions by utilizing concentrated solar power. However, one of the challenges to continuous methane pyrolysis is deactivation of catalyst, when present, and establishing a facile means of extracting the valuable carbon product. In this work, a scalable route to continuous solar-thermal methane pyrolysis is presented that employs a roll-to-roll mode of operation. A high-flux solar simulator is used to mimic concentrated solar power and to allow operation at temperatures of approximately 1500 K, where methane rapidly decomposes onto the fibers of a porous carbon roll, collecting graphitic solid carbon and exhausting clean hydrogen fuel in addition to unconverted methane. The efficacy of the roll-to-roll approach for methane decomposition is investigated, and the technique is observed to be effective in achieving a continuous process. The roll-to roll mechanism maintains stable and relatively high methane conversion compared to a stationary substrate, where enhancement in methane conversion as high as 42% is observed. The quality of the carbon product obtained is generally high, with Raman D/G peak ratios near 0.5. This work therefore establishes a proven baseline for continuous production of graphitic carbon from solar pyrolysis.
Keywords Methane decomposition, Solar processing, Graphitic carbon production, Clean hydrogen, Roll-to-roll