Kinetics of low temperature hydrogen reduction of the metastable spinels

Autor: D. N. Drakshayani, R. M. Mallya
Rok vydání: 1994
Předmět:
Zdroj: Journal of Thermal Analysis. 42:937-950
ISSN: 1572-8943
0368-4466
DOI: 10.1007/bf02547115
Popis: The kinetics of reduction at relatively low temperatures with hydrogen of pure and doped metastable non-stoichiometric magnetite with 1 at% Mn, Co, Ni and Cu and also with 5 at % Ni and Cu have been investigated by using isothermal thermogravimetry in the temperature range 300–400°C. With increase in the concentration of the dopant (5 at% Ni and Cu), the reactivity increases. The activation energies for pure magnetite varies from 7 to 9 kcal/mole with the preparation temperature of precursorf Fe2O3 (250–400°C), being the lowest for those prepared at the lowest temperatures. The corresponding activation energies for the reduction of doped samples (Fe, M)3−zO4, it depends, apart from their porosity and surface areas, on the nature of the solute atom, amount of disorder, whether it occupies the tetrahedral (A) or octahedral (B) sites in the non-stoichiometric spinel and possibly on hydrogen ‘Spill over’ effects.
Databáze: OpenAIRE
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