Enhancement of low-temperature activity and sulfur resistance of Fe0.3Mn0.5Zr0.2 catalyst for NO removal by NH3-SCR

- The catalyst exhibits 100% NO conversion at 200-360 °C.
- The catalyst gives excellent stability and strong SO2 resistance at 200 °C.
- The addition of Fe to Fe0.3Mn0.5Zr0.2 can significantly broaden wide work-window.
- Mn oxides and Fe oxides in Fe0.3Mn0.5Zr0.2 exhibit gradually metallic ions.
- The amorphous MnO2 and Fe2O3 play a dominant role for NO oxidation.

A novel Fe0.3Mn0.5Zr0.2 catalyst was prepared by co-precipitation method and used to remove NO at 80-400 °C. The physicochemical characteristics of samples were studied by N2 adsorption-desorption, SEM, XRD, XPS and temperature-programmed technology. The results showed that Fe0.3Mn0.5Zr0.2 exhibits better removal ability of NO with NH3 and NO conversion achieves 100% at 200-360 °C. Moreover, it gives a good stability and strong SO2 resistance at 200 °C. Fe0.3Mn0.5Zr0.2 has 309 m2/g of BET surface area and 0.358 cm3/g of mesopore volume, which are beneficial for gas adsorption and diffusion. The amorphous MnO2 and Fe2O3 play a dominant role for NO oxidation due to their strong redox property and high lattice oxygen (Oα) concentration. Oα in Fe0.3Mn0.5Zr0.2 can quickly oxidize NO to NO2, which promotes the “Fast SCR” reaction. The strong interactions among Fe, Mn and Zr of Fe0.3Mn0.5Zr0.2 lead to its strong thermal stability and sulfur resistance, but the increase of the absorbed oxygen species changes the valence electron distribution of Mn and Fe after it working at 200 °C for 80 h. Mn oxides and Fe oxides in Fe0.3Mn0.5Zr0.2 exhibit gradually metallic ions after SO2 with 100/200 ppm concentration is induced into simulated gases at 200 °C for 53 h. In addition, Fe0.3Mn0.5Zr0.2 possesses both Brönsted and Lewis acid sites. They promote the adsorption and activation of NH3, resulting a good low-temperature SCR activity.