在氧化铁表面沉积热解炭及其气化与还原

Thermodynamic analysis and chemical vapor deposition (CVD) of pyrolytic carbon on the surface of needle-like goethite (FeOOH) in a flow reactor were carried out. It was found that CVD of carbon from propylene occurred on the surface below 600℃. With the deposition of pyrocarbon, the surface area of the FeOOH decreased rapidly and mass loss occurred resulting from dehydration. With increasing CVD temperature, Fe2O3 was reduced gradually to Fe3O4 and FeO and finally Fe3C as the CVD temperature exceeded 800℃. Carbon deposited on the surface of iron oxide below 500℃ limited the morphological change of nano FeOOH from large aspect ratio particles to spherical particles. At higher temperatures (600-700℃), carbon deposition led to the formation of dumbbell shaped iron oxide. The two forms of iron oxide can be reduced by carbon monoxide or hydrogen into pure iron or carbon coated iron with high aspect ratios or a dumbbell shape.