Kinetic characterization of the reduction of silica supported cobalt catalysts

Abstact  The reduction process of silica supported cobalt catalyst was studied by thermal analysis technique. The reduction of the catalyst proceeds in two steps: which was validated by the TPR and in-situ XRD experiments. The kinetic parameters of the reduction process were obtained with a comparative method. For the first step, the activation energy, E _a, and the pre-exponential factor, A, were found to be 104.35 kJ mol⁻¹ and 1.18·10⁶∼2.45·10⁹ s⁻¹ respectively. The kinetic model was random nucleation and growth and the most probable mechanism function was found to be f(α)=3/2(1−α)−ln(1−α)]^1/3 or in the integral form: g(α)=−ln(1−α)]^2/3. For the second step, the activation energy, E _a, and the pre-exponential factor, A, were found to be 118.20 kJ mol⁻¹ and 1.75·10⁷∼2.45 · 10⁹s⁻¹ respectively. The kinetic model was a second order reaction and the probable mechanism function was f(α)=(1−α)² or in the integral form: g(α)=1−α]⁻¹−1.