Oxidation Kinetics Of Magnesium Sulfite Catalyzed By A Novel Cobalt-based Molecular Sieve

The flue gas desulfurization is the main method to reduce the emission of SO2 from the industrial boilers. Magnesia desulfurization is apparently excellent in many wet desulfurization technologies, due to its advantages such as high removal efficiency, simple process, little scaling, and stable operation and so on. Magnesia desulfurization has obvious development prospect in industrial boilers of our country. Oxidation of magnesium sulfite plays an important role for recycle of byproduct in the magnesia desulfurization, which can be significantly accelerated by catalysts of transition metals. However, these catalysts were added in type of ions at present, and the previous theoretical research focused on the effect of liquid catalysts. The catalysts in solution can not be recycled, and we have to replenish periodically in order to guarantee its oxidation effect, resulting in a high cost of application and serious secondary pollution. So developing a kind of catalyst, which has advantage of efficient, stable and recoverable, had become the new development tendency.In this paper, a novel supported catalyst was prepared by loading the transition metal ions of Co2+ on the molecular sieve carrier, employing the wet impregnation method. According to the result of orthogonal experiment, the five factors impacting the performance of catalyst such as pretreatment technology, load of Co, first calcinations, temperature of final calcinations and calcinations time were studied. Finally, the optimum technological condition was determined. This supported catalyst was identified by SEM, XRF, BET, XRD and EDS measurements as well, researching the properties of the catalyst and the load situation of active constituent cobalt.The macroscopic oxidation kinetics of magnesium sulfite was investigated in a stirred tank reactor with bubbling. The general reaction orders with respect to the catalyst, magnesium sulfite and oxygen were achieved to be 0.4, 0 and 0.4 respectively, and the apparent activity energy is 24.43 kJ?mol-1. Furthermore, the kinetic mechanism in presence of the supported catalyst was revealed, indicating the mass transfer of oxygen might be the rate controlling step.Through studying magnesium sulfite solid-phase catalytic oxidation theory, a new approach for recycle of byproduct in magnesium desulfurization was provided. The research result will develop the controlled theory of sulfite oxidation from liquid catalytic stage to solid catalytic stage, resulting in much breakthroughs in the application of the oxidation catalysts in the desulfurization, which has theoretical significance and practical value.