New insights into the relationships between performance and physicochemical properties of FeOx–NbOx mixed oxide catalysts for the NH3-SCR reactions

摘要

Abstract In this study, we prepared Fe2O3–Nb2O5 binary mixed oxide catalysts using co-precipitation (CP), sol-gel (SG), and solid process (SR) methods and tested their performance. All the catalysts exhibited over 75% NOx removal efficiency between 250 °C?and 400?°C. Compared with the samples prepared by the SR method, catalyst synthesized using CP and SG methods possessed a larger specific surface area, which could compensate for the lower surface area-normalized reaction rate originating from the insufficient reactive surface oxygen species, hence exhibiting a relatively high low-temperature apparent deNOx activity. However, at a high-temperature region, limited amount of reactive surface oxygen species, together with abundant strong acid sites, facilitated the proceeding of NH3 reduction of NOx, which well explained the higher apparent activity of the catalyst prepared by SG method than the other two samples. It seemed that specific surface area had an important role to play in the low-temperature apparent performance of the catalysts, while chemical properties mainly decided the activity at an elevated temperature.