Natural Fe-based catalysts for the production of hydrogen and carbon nanomaterials via methane decomposition

Tierga and Ilmenite Fe-based ores are studied for the first time in the catalytic decomposition of methane (CDM) for the production of carbon dioxide-free hydrogen and carbon nanomaterials. Tierga exhibits superior catalytic performance at 800 °C. The effect of the reaction temperature, space velocity and reducing atmosphere in the catalytic decomposition of methane is evaluated using Tierga. The highest stability and activity (70 vol% hydrogen concentration) is obtained at 850 °C using methane as a reducing agent. Reduction with methane causes the fragmentation of the iron active phase and inhibits the formation of iron carbide, improving its activity and stability in the CDM. Hybrid nanomaterials composed of graphite sheets and carbon nanotubes with a high degree of graphitization are obtained. Considering its catalytic activity, the carbon quality, and the low cost of the material, Tierga has a competitive performance against synthetic iron-catalysts for carbon dioxide-free hydrogen and solid carbon generation.