Iron ore catalysts for methane decomposition to make CO x free hydrogen and carbon nano material

Abstract In this work, for the first time, iron ores with 91.7%–96.2% Fe 2 O 3 , 1.3%–2.3% Al 2 O 3 , 1.2%–4.5% SiO 2 , 1.3%–3.9% Na 2 O, were studied directly as bulk catalysts for methane decomposition. By hydrogen pre-reduction at 850 °C, Fe 2 O 3 species on iron ores were gradually reduced into Fe 3 O 4 , FeO and then finally into Fe 0 species. After reduction of 1.6 g of iron ore catalysts of 50 µm particle size with 100 mL/min pure H 2 for 3.5 h at 850 °C, CMD life testing was conducted at 850 °C and GHSV of 3.75 L/g cat  h and the catalyst showed a stable methane conversion for 5 h. When methane decomposition proceeded on Fe 0 sites, Fe 3 C species would be formed to deposit graphite around themselves to finally form carbon nano onions. This carbon nano onions material showed excellent application for wastewater purification. All samples were fully characterized with XRF, XRD, H 2 -TPR, TEM and Raman.