Research On Low-Temperature Manganese-Base Oxide Denitration Catalyst

Nitric oxides (NOX) is a common air pollutant, which can cause series of environment problem such as photochemical smog, the atmospheric acid deposition, urban haze and so on. So NOX pollution control has a great significance to improve air quality. Ammonia selective catalytic reduction (NH3-SCR) is widely used to flue gas denitrification. As the commercial V2O5/TiO2 catalyst system which have an narrow temperature range (300?400?) and a poor activity in the low temperature. Therefore, developing a SCR technology with high activity in the lower temperature has drew deep attention among the research personnels.Catalysts with metal of manganese were prepared by impregnating method, the influence of MnOx loading, calcination temperature, Ce addition, carrier and preparation method on its SCRactivity were studied, and the catalysts were also characterized by XRD?BET?NH3-TPD? H2-TPR and XPS methods to study itsphysical and chemical properties. Main conclusions from this work are as follows:1?he zeolites of USY, (3 and ZSM-5 as carrier, Mn loading is 20wt%,15wt% and 15wt%, calcination temperature is 300?, catalysts all exhibit a high reaction activity for low-temperature denitration.2?Low-temperature denitration activity of Manganese-based oxide catalysts have an significant improvement after Ce-doped. The catalyst has a better denitration efficiency with Mn/Ce=2:1 (molar ratio), relatively. XRD and SEM analyses reveal that Ce-doped can promote the dispersion of Mn on the catalysts surface. H2-TPR characterization found that Ce-doped can increase its low temperature reduction peak area and decrease lower temperature reduction of peaks temperature.3?Compard with the catalysts that ? and ZSM-5 as the carrier, the catalyst with USY as carrier shows a higher reaction activity for low-temperature denitration, this is because it has more active oxygen species and weak acid sites on its surface, meanwhile the higher of Mn4+/Mn3+ value and adsorbed oxygen concentration on the catalyst surface may beneficial to raising the activity of low-temperature denitration at low temperature.4?The silica alumina ratio of carrier has a great effect on catalytic activity. The catalyst with (3-40 as the carrier, exhibits a better denitration efficiency relatively. The catalyst, ?-40 as the carrier, has a larger specific surface area and lower temperature reduction of peaks temperature.5?Loading sequence have a great effect on catalytic activity. The catalyst, Mn and Ce were supported on the same time, has the best denitration efficiency relatively. The catalyst, Mn and Ce were supported on the same time, has a biger surface area and a lower temperature reduction of peaks temperature.6?Ultrasonic has some effect on catalytic activity.The catalyst, optimum ultrasonic time is 20 min, shows a higher denitration efficiency relatively.XRD characterization found that the ultrasonic can promote the dispersion of active components on the carrier surface, and its low temperature reduction of peaks temperature is lower than the others.7?Metal modified zeolite as carrier may beneficial to catalytic activity. Fe modified zeolite as carrier, shows a higher denitration efficiency relatively. XRD characterization proved that the Fe modified has a great influence on the structure of zeolite and active components on the catalysts surface are highly dispersed. H2-TPR analyses indicate that its low temperature reduction of peaks temperature is lower than the others, it has a stronger low temperature reduction ability as follows.