INVESTIGATION OF THE KINETICS OF REDUCTION OF NICKEL-OXIDE AND NICKEL ALUMINATE BY HYDROGEN

The reduction kinetics of NiO and NiAl2O4 in hydrogen have been studied by thermogravimetric measurements. In the case of NiO, the experiments were restricted to the temperature range 564 to 782 K due to the high rate of the reaction whereas, in the case of the aluminate, due to the sluggishness of the reduction, a higher temperature range of 1287 to 1537 K was employed. The activation energy for the reduction of NiO was evaluated to be 18 kJ/mol while the corresponding value for the aluminate was 134 kJ/mol. The difference in the activation energies is discussed in terms of the bond strengths. The morphology of the reduced specimens shows that the method is promising in the preparation of alumina-based nickel catalysts.