High catalytic activity of Mn-based catalyst in NO oxidation at low temperature and over a wide temperature span

A series of PEG modified Mn-based catalysts synthesized by precipitation method were surveyed to evaluate their catalytic performances for NO oxidation. At the calcination temperature lower than 500 degrees C, the Mn-based catalysts are all the crystal structure of gamma-MnO2, while other catalysts at calcination temperatures of 600-800 degrees C possess the crystal structure of Mn2O3. gamma-MnO2 exhibits better catalytic behavior for NO oxidation than Mn2O3, and obtains the maximum NO conversion of 93% at 220 degrees C with a mass space velocity of 48 000 mL g(-1) h(-1). Compared with Mn2O3, gamma-MnO2 also shows better low-temperature performance with the conversion of above 50% at 130 degrees C, and in a wide temperature span from 130 degrees C to 380 degrees C with a mass space velocity of 48 000 mL g(-1) h(-1). This activity temperature window is even broader than that of some noble metal catalysts. The physico-chemical characteristic was fully analyzed through XRD, BET, SEM, H-2-TPR, NO/O-2-TPD, XPS, DRIFTS and FT-IR, and the characterization results demonstrate that PEG can lead to an excellent catalytic activity, because it not only increases the surface area of the catalyst, but also enhances the adsorption of O-2 and NO at low temperature.