Research On The Theory Of Solid-phase Catalytic Oxidation Of Wet FGD Sulfite

Currently sulfur dioxide makes environmental pollution becoming more andmore serious. Flue gas emitted from industrial boilers is not only one of the majorsources of SO2, but also one of the causes of fog and haze. Wet desulfurization is akind of common flue gas desulfurization technology which mainly includes:limestone/gypsum method, magnesium oxide method, double alkali method, Sodiumprocess, etc. Magnesia desulfurization has been used widely in industrial boilers fluegas desulphurization in recent. However, due to lonized catalyst which was used inthe magnesium sulfite catalytic oxidation having not been recovered effectively, itneeds to be replenished periodically, then it increases operating costs. Part of lonizedcatalyst is brought into magnesium sulfate, and it must affects the economic value ofmagnesium sulfate. Then another part is brought into water environment withdesulfurizing efflux liquid, and it causes water pollution. So it hinders desulfurizationbyproducts recycling and the technology’s promotion.Magnesium sulfite was regarded as typical to study the theory of sulfite catalyticoxidation in this paper. The cobalt salt was used as the main active component of thecatalyst, and the solid-phase catalyst was prepared by co-precipitation method. Thenthe best catalyst preparation conditions were screened by orthogonal experimentsfrom the factors of affecting the catalytic activity, such as the content of cobalt salt inthe catalyst, whether washing the catalyst, evaporated water bath or filtration,whether calcining at250℃, and the final calcination temperature. The bestpreparation conditions were as follows: the content of cobalt salt=6M, unwashed,evaporated water bath (filtration), calcining at250℃,the final calcinationtemperature=450℃.The catalyst which was obtained in the best preparation conditions was used tostudy magnesium sulfite oxidation reaction kinetics. It studied the macro reactionkinetics and reaction mechanism of magnesium sulfite oxidation under the solid-phasecatalyst by changing some conditions, such as the initial concentration of magnesiumsulfite, catalyst mass concentration, oxygen partial pressure, air flow, pH, temperature,etc. The results indicate that the general reaction process was greatly influenced bycatalyst mass concentration, oxygen partial pressure and temperature. The reactionorders for catalyst mass concentration, oxygen partial pressure, and the initial concentration of magnesium sulfite are0.35,0.41,0respectively, and the apparentactivation energy is13.24kJ.mol-1.Combining the characterization results, three-phasereaction process model was established, and the reaction mechanism of the catalyticoxidation of magnesium sulfite was inferred initially. Through studying the losscharacteristics of catalyst, it proved the prepared catalyst achieving the expectedgoals.Through studying magnesium sulfite solid-phase catalytic oxidation theory, it notonly provides a reference for studying the sulfite solid-phase catalytic oxidationmechanism, and offers a scientific basis for solid-phase catalyst applying to the sulfiteoxidation reaction in the future.