Production of Carbon Fibers Using a Molten Cu-In Catalyst for Methane Pyrolysis.

Molten metal catalysts for methane pyrolysis and dry reforming are becoming recognized for their potential in decarbonization efforts. Their use in bubble column reactors facilitates continuous operation by allowing the produced carbon to float to the surface for removal. While most reported molten metals produce low-value amorphous carbon or graphitic sheets containing some metals, our study introduces a Cu-In alloy that selectively produces high-purity carbon nanofibers. These nanofibers are tubular and have a smooth or bamboo-like segmented structure with a diameter of approximately 100 nm. We have identified a droplet-based pathway for the growth of these fibers and removal of the droplets, observed consistently across a bubble column reactor, a surface reactor, and both in the absence and presence of carbon dioxide for pyrolysis and dry reforming. The molten Cu-In system is shown to outperform other molten metal catalysts, producing fibers with a purity greater than 99.9% after heat treatment.