Removal of NO by Reversible Adsorption on Fe−Mn Based Transition Metal Oxides

A series of Fe−Mn-based transition metal oxides were prepared and used for NO adsorption at 25 °C in the presence of O 2 . The sorbents were also characterized by BET surface area, TPD, XRD, and FTIR spectroscopy. Both TGA and chemiluminescent NO/NO x analyzer experiments showed that the mixed oxides were efficient and reversible sorbents for NO removal. The NO x capacity decreased in the order of Fe−Mn−Ti, Fe−Mn−Zr > Fe−Mn−Ce, Fe−Mn−Ni > Fe−Mn−Co > Fe−Mn−Cu, Fe−Mn. The maximum NO x capacity reached 42−45 mg/g of sorbent for the Fe−Mn−Ti and Fe−Mn−Zr oxides. SO 2 and CO 2 decreased the NO x adsorption amount only slightly. H 2 O decreased the NO x adsorption significantly, but the inhibition was reversible. TPD profiles indicated that NO x species could desorb at temperatures below 400 °C. The high efficiency for NO removal on these oxides was related to their high activities in NO oxidation to NO 2 at 25 °C. FTIR spectra showed that the nitrate was the final species for NO adsorption. NO 2 and nitrite were the intermediates during nitrate formation on the oxides.