Methane decomposition to produce hydrogen and carbon nanomaterials over costless, iron-containing catalysts

摘要

In this work, a series of iron-containing materials (not laboratory-synthesized but from natural, industrial raw materials, by-products or wastes), such as iron concentrate powder, fine/coarse ash and steel slag from steel plants and volcanic mud powder, were investigated as catalysts for methane decomposition. These catalysts exhibited relatively good methane conversion under the following conditions: 2.0 g of catalyst, 50 mL/min CH4, 900 degrees C for 5 h, even without hydrogen pre-reduction. Fe2O3 species on these samples were found to be gradually reduced by methane to Fe3O4, FeO and then finally into Fe-0 active species. When methane decomposed onto the Fe-0 active sites, Fe3C species would form to deposit graphite around themselves to finally form carbon nano-materials, showing possible application in the oxygen evolution reaction and in Li-ion batteries as anode electrodes. Furthermore, using the best catalyst, iron concentrate powder, the effect of temperature and gas hourly space velocity was studied, where 900 degrees C and 3 L/g(cat).h were determined as the optimized reaction conditions to reach the highest carbon/hydrogen yield.