Biochar supported manganese based catalyst for low-temperature selective catalytic reduction of nitric oxide

This research work aims to study the performance of biochar-supported manganese-based catalysts for conversion of NOx in the selective catalytic reduction (SCR) process. Biochar, a high energy density solid generated from biomass pyrolysis, usually is combusted to provide extra heat to the pyrolysis process. Compared to other carbonaceous materials, biochar has a larger surface area, large surface functional groups and is more economically advantageous. An experimental and observational methodology was adopted in which biochar with activation temperatures of 500 °C, 600 °C, and 700 °C were used as additional catalytic support to the Manganese-based SCR catalyst. The prepared samples were analyzed by various techniques like X-ray diffraction, Scanning electron microscopy, X-ray photoelectron spectroscopy, NH₃-Temperature-programmed desorption and H₂-Temperature programmed reduction to study various parameters like crystallographic structure and crystal properties, chemical states and elemental composition, surface acidity, and reducibility of the catalyst. Upon adding biochar, it was observed that the pore volume increased by 150% and the surface area by 114%. Subsequently, catalytic activity tests were conducted on the effect of biochar on NOx removal, SO_2, and H₂O tolerance, and the optimum catalyst composition were found. Catalytic performance increases with the addition of biochar over all temperature ranges, with Mn/TiO₂-Char₇₀₀ reaching a maximum NOx conversion rate of 90%, indicating that biochar is a viable alternative to existing catalytic supports.