Design of assembled composite of Mn3O4@Graphitic carbon porous nano-dandelions: A catalyst for Low–temperature selective catalytic reduction of NOx with remarkable SO2 resistance

The biggest challenge for selective catalytic reduction (SCR) of NO by NH 3 at low temperatures is to develop robust catalysts with high resistance to SO 2 . Mn-based catalysts have attracted great attention for their excellent activity, but the poor SO 2 resistance limits their application. Herein, we report a novel assembled composite featuring Mn 3 O 4 nanoparticles embedded in defect-abundant graphitic carbon frame (Mn 3 O 4 @G-A) via a confinement–pyrolysis–oxidation strategy derived from MOF. The Mn 3 O 4 @G-A exhibits excellent activity (reaching over 90 % NO conversion in 100, 000 h −1 GHSV at 160 °C) and significantly improved SO 2 resistance in comparison to pristine Mn 3 O 4 , and all the performance tests were conducted with 5.6 vol.% water vapor. By combining synchrotron radiation-based X-ray absorption spectroscopy and density functional theory calculation, we further discovered the positive role and the origin of graphitic carbon for improving SO 2 resistance. Over the Mn 3 O 4 @G-A sample, the electrons can be transferred from graphitic carbon to Mn 3 O 4 nanoparticles, which can regulate the electronic properties and oxidizing ability of Mn 3 O 4 nanoparticles. The proper oxidizing ability of Mn 3 O 4 @G-A can inhibit the oxidation of SO 2 to SO 3 , thus further avoid the formation of NH 4 HSO 4 and improve the SO 2 resistance. Our work here not only solves the current problem of poor SO 2 resistance of Mn-based catalysts, but also provides new insights into the design and synthesis of MOF-derived graphitic carbon-containing catalysts for SCR applications.