A Study On Simultanueous Desulfurization And Denitration By Catalytic Reduction Method

The emission of SO₂ and NO from burning coal are two major atmospheric pollutants. Simultaneous removal of SO₂ and NO pay more attentions because of its advantages, such as saving area, reducing costs of investment and operating. Because of reducing SO₂ and NO into S and N2, simultaneous catalytical reduce method can eliminate the regeneration process and reutilize the sulfur resource. It is a promising method in the future industrial application.A series catalysts of Y/AC?Fe/AC?Co/AC and modified with transition metallic oxide were prepared with incipient impregnation. Performance of simultaneous removal of SO₂ and NO were examined in a minature fix bed reactor with analogy flue gas. The sample crystal phase structure was analyzed with XRD. The capability of hydrogen reduction, morphology and specific surface area of the catalysts were charactrized with H2-TPR, SEM and BET, respectively.Experimental results shown that catalysts loading of Y oxide on the AC between 6%-8%showed excellent performance of simultaneous desulfurization and denitration. Pretreatment of carrier AC with HNO3 would increase the catalysts performance. Presulfidation process could also promote catalyst feature. Experiment result indicated catalyst presulfiding under 550? expressed best performance of denitration. The catalyst would partly resume active if the catalyst deactivated in low concentration of O₂ ambient. However, deactivation of the catalyst in high concentration of O₂ would permanently lost reaction activity. The mechanism of desulfurization and denitration both conformed with COS for catalyst Y/AC reaction.Based on 6% loading of Y/AC, sample doped with 0.5% Ni oxide displyed most performance of desulfurization and denitration. The the temperature with 90% conversion rate of SO₂ and NO is 370? and 360?, respectively. The crystal phase structure of the catalysts Y/AC modified with Ni would change and obvious active decrease was observed if there was O₂ in the reaction material gas. The NiS2 crystal phase structure disappeared and NiO crystal phase was observed. And the crystal phase structure of NiS still existed.The mechanism of simultaneous desulfurization and denitration was studied by transient response reaction method for Fe/AC catalyst. Redox and COS mechanism were both existed. For Fe/AC catalysts, the ability of desulfurization and denitration would be enhanced by modified with Y, La, Ce, Co.For loading of 10% Fe, catalysts with carriers ZrO₂ and H-? possessed excellent performance of desulfurization and denitration. Support of ZSM?TiO₂, USY and MCM expressed weak activity.