Highly porous MnOx prepared from Mn(C2O4)·3H2O as an adsorbent for the removal of SO2 and NH3

Abstract In this work, the possibility of substituting metal impregnated activated carbon with nanoporous metal oxides for the adsorption of SO 2 and NH 3 was investigated. Nanoporous manganese oxide (MnO x ) was prepared from manganese oxalate trihydrate by thermal decomposition in air. The physical properties of the oxalate precursor and the resulting MnO x samples were characterized with SEM, TGA-DSC, mass spectroscopy, FTIR and powder XRD. The specific surface areas and porosity of MnO x were studied by single-point and multi-point BET measurements. The amorphous needle-like MnO x had a specific surface area of over 500 m 2 /g when the precursor was heated at 225 °C for 6 h. Dynamic SO 2 and NH 3 flow tests indicated that the adsorption capacity of MnO x depends primarily on the surface area. Compared to Mn 3 O 4 -impregnated activated carbon, nanoporous MnO x could remove about twice as much SO 2 and 15% more NH 3 per gram of adsorbent. This could lead to respirators of lower weight and smaller size which will be attractive to users.