Oxidation rate of magnesium sulfite catalyzed by cobalt ions.

Oxidation of magnesium sulfite is important for recycle of byproduct in the magnesium desulfurization. The oxidation rate of magnesium sulfite, prepared by vacuum evaporation method, was investigated in a bubbling tank in presence of transition metal catalysts, which shows cobalt is the most effective. The general reaction orders with respect to cobalt, magnesium sulfite, and oxygen are 0.44, 0, and 0.46, respectively, and the apparent activity energy is 17.43 KJ·mol. The catalytic performance of cobalt compared with other metals was also analyzed employing the ion potential theory. Integrated with the three-phase reaction model, we inferred that the general oxidation rate of magnesium sulfite is controlled by mass transfer of oxygen. Further, the intrinsic kinetics was predicted, indicating that the reaction orders with respect to cobalt and oxygen are 1.0 and 0, respectively. The results are helpful for the recycle of magnesium sulfite in magnesia desulfurization.