Role of CuO in improving NH and SO capture on nanoporous FeO sorbents.

In this work, mixed Fe/Cu oxides as sorbents for SO and NH removal were investigated. Nanoporous iron oxide mixed with 10, 20 and 30 at.% CuO were prepared by thermal decomposition of the corresponding oxalates at 250 °C for 5 h in air. The mixed Fe/Cu oxalates were obtained from the co-precipitation of iron/copper sulfate and ammonium oxalate during ultrasonication. The physical properties of the oxalate precursors and the resulting mixed Fe/Cu oxides were characterized with SEM, TGA-DSC, FTIR, powder XRD and Mössbauer spectroscopy. The porosity was studied by N adsorption-desorption isotherms and small angle X-ray scattering. Evenly dispersed CuO hindered the crystallization of FeO, which significantly increased the specific BET surface area from 211 m/g for FeO to 354 m/g for FeCuO. As a result, SO and NH adsorption on FeCuO were enhanced by about 70% compared to FeO. Compared to FeO-impregnated activated carbons, nanoporous FeCuO could capture five times more SO per unit weight, which will be attractive for applications in respirators with lower weight and smaller size.