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 NH3 at low temperatures is to develop robust catalysts with high resistance to SO2. Mn-based catalysts have attracted great attention for their excellent activity, but the poor SO2 resistance limits their application. Herein, we report a novel assembled composite featuring Mn3O4 nanoparticles embedded in defect-abundant graphitic carbon frame (Mn3O4@G-A) via a confinement-pyrolysis-oxidation strategy derived from MOF. The Mn3O4@G-A exhibits excellent activity (reaching over 90 % NO conversion in 100, 000 h(-1) GHSV at 160 degrees C) and significantly improved SO2 resistance in comparison to pristine Mn3O4, 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 SO2 resistance. Over the Mn3O4@G-A sample, the electrons can be transferred from graphitic carbon to Mn3O4 nanoparticles, which can regulate the electronic properties and oxidizing ability of Mn3O4 nanoparticles. The proper oxidizing ability of Mn3O4@G-A can inhibit the oxidation of SO2 to SO3, thus further avoid the formation of NH4HSO4 and improve the SO2 resistance. Our work here not only solves the current problem of poor SO2 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.