SYNTHESIS OF CARBON-IRON(II) OXIDE LAYER ON THE SURFACE OF MAGNETITE AND ITS REACTIVITY WITH H2O FOR HYDROGEN GENERATION

Synthesis of a carbon-iron(ll) oxide layer on the surface of magnetite and its reactivity with H2O for hydrogen generation reaction have been studied. X-ray diffractometry and chemical analysis showed that the carbon-bearing magnetite synthesized by the carbon-deposition reaction from CO2 gas with the hydrogen-reduced magnetite, was magnetite with a carbon-iron(II) oxide layer (CIO layer-M; M is stoichiometric magnetite) represented by (Fe3O4)1-delta (Fe3O3)delta(tau). The TG-MS spectra also showed the evidence for the formation of the CIO layer on the bulk stoichiometric magnetite. Some amorphous phase was formed in the ClO layer during the activation step (in vacuo at 300 degrees C for 30 min). This amorphous phase reacted with H2O and evolved H-2 gas at 350 degrees C. This H-2 generation reaction resulted in the oxidation of the CIO layer into gamma-Fe2O3 component and the release of a part of carbon in the CIO layer as CO2. The X-ray diffractometry and Mossbauer spectroscopy indicated that the solid solution of Fe3O4-gamma-Fe2O3 was formed in the solid phase after the H-2 generation reaction. This shows the cation movement in the B site of the bulk magnetite of the activated CIO layer-M during the H-2 generation reaction. The TG-MS spectra also supported the above estimation.