Kinetic studies have been carried out on the hydrogen reduction of pure α-Fe2O3 doped with foreign metal oxides employing a sensitive micro-gravimetric technique. The results show that the reduction of pure Fe2O3 proceeds by a consecutive two-step mechanism via Fe3O4, the overall rate being controlled by the topochemical reduction of Fe3O4 while that of doped oxides and hematite ore takes place by a different mechanism involving the mixed ferrite formed. In addition, the reduction of pure Fe2O3 is catalysed by metal additives in the presence of water vapour. This enhancement in reduction rate is attributed to a "hydrogen spill-over" effect. © 1982.

Ram Prasad Viswanath

Balasubramanian Viswanathan

CHEMICAL REACTIONS - REDUCTION

Hydrogen

iron oxide

Iron compounds

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

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IIT Madras

Studies on the reduction of iron oxide with hydrogen

International Journal of Hydrogen Energy

Surface analyses (X-ray photoelectron spectroscopy, X-ray-induced Auger electron spectroscopy and Auger electron spectroscopy) results of some hydrogen storage intermetallic compounds of the type AB, AB5, A2B and the hydride, A2BH4 (A ≡ Ti, La, Ca or Mg; B ≡ Fe, Ni or Cu) show the presence of numerous oxidation (aerial) products, such as oxides, hydroxides and carbonates. In general, the hydroxide and/or carbonate species are present in small amounts and persist only on the outer passivated surface. However, there are cases where they seem to be predominant, at least in the top few layers. Therefore such species are also expected to play an important role in the surface chemistry of the alloys and hydrides similar to that observed with surface oxides. Accordingly, the activation procedure varies for the different materials. Upon activation the surface may be described as a supported metal system which in turn increases the activity thus explaining the rapid kinetics of the hydriding/dehydriding reactions upon cycling processes. The easy activation of certain alloys could also be explained on the basis of the reducibility and the thickness of the surface oxide layers. In other words, it could be demonstrated based on their oxidation resistance and the segregation behaviour of the metals. The specific reactivity of different systems are related to the segregation, oxidation, and reduction behaviours. Surface enrichment of iron in the TiFe system is demonstrated for the first time. © 1990.

Journal	International Journal of Hydrogen Energy
ISSN	03603199
Open Access	No