Kinetics Study on Molybdenum Leaching from Spent Catalyst in Ammonium Hydroxide Solution

The aim of the present work is to study the kinetics of leaching process of spent catalyst Ni, Mo/Al2O3 in order to recover the molybdenum using ammonium hydroxide. The investigation depends on the results of previous work ( Mousa et al, 2012). The experiments were conducted in 1-liter stainless steel autoclave. Kinetics study showed that both the diffusion through ash layer and the reaction on the surface of particles between the molybdenum and the ammonium hydroxide effect on the kinetics. The activation energy for reaction model was found to be equal to 6.706 kJ/mol, while the activation energy when using the ash layer model was 24 kJ/mol. The values of activation energies indicate that the intermediate or mixed is controlled the process.