Highly efficient MnOx/biochar catalysts obtained by air oxidation for low-temperature NH3-SCR of NO

In this study, a novel air oxidation treatment strategy was proposed to modify Mn-doped biochar catalysts for enhanced removal of NO at low temperature. The pre-oxidation at 400 degrees C and post-oxidation at 250 degrees C under air atmosphere was applied respectively before and after impregnating biochar with Mn-containing solution (BC-OMO). The results showed that, after pre-oxidation the specific surface area and total pore volume of the sample increased to 734 m(2)/g and 0.440 cm(3)/g respectively in comparison with those without pre-oxidation (557 m(2)/g and 0.353 cm(3)/g). After further post-oxidation, the contents of Mn4+ and chemisorbed oxygen (O-alpha) in BC-OMO increased to 36.2% and 49.8% respectively from those without air oxidation (25.4% and 38.7%), which could enhance the surface acidity and redox capabilities of the catalysts. The denitration results showed that the conversion efficiency of NO for BC-OMO catalyst reached as high as 97.0% at 150 degrees C, which was significantly higher than that without air oxidation (61.8%). The mechanisms for improving denitration efficiency of MnOx/biochar catalysts by pre- and post-air oxidation were also discussed.

Automated summary

A novel air oxidation treatment strategy was proposed to modify Mn-doped biochar catalysts for enhanced removal of NO at low temperature. The results showed that air oxidation significantly increased the specific surface area and total pore volume of the catalysts, enhancing their surface acidity and redox capabilities, leading to improved efficiency in NO conversion.