Search Results

You are looking at 1 - 2 of 2 items for

  • Author or Editor: D. Drakshayani x
  • All content x
Clear All Modify Search

Kinetics of low temperature hydrogen reduction of the metastable spinels

Magnetite and solid solutions with Mn, Co, Ni and Cu

Journal of Thermal Analysis and Calorimetry
Authors: D. Drakshayani and R. Mallya

Abstract  

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.

Restricted access