A novel one-step synthesis of Ce/Mn/Fe mixed metal oxide nanocomposites for oxidative removal of hydrogen sulfide at room temperature.

In this study, CeO 2 /Fe 2 O 3 , CeO 2 /Mn 2 O 3 , and CeO 2 /Mn 2 O 3 /Fe 2 O 3 nanocomposites were synthesized by the calcination of molten salt solutions. The microscopic images confirmed polyhedral nanocrystals of 10-20 nm size, clustered to form nanospheres. The elemental mapping confirmed the uniform distribution of transition metal oxides in the CeO 2 matrix. The X-ray diffraction analysis confirmed the phase purity of metal oxides in nanocomposites. The surface area of nanocomposites was in the range of 16-21 m 2 g -1 . X-ray photoelectron spectroscopy confirmed 25-28% of Ce 3+ ions in the CeO 2 of nanocomposites. These nanocomposites were tested for the removal of hydrogen sulfide gas at room temperature. The maximum adsorption capacity of 28.3 mg g -1 was recorded for CeO 2 /Mn 2 O 3 /Fe 2 O 3 with 500 ppm of H 2 S gas and 0.2 L min -1 of flow rate. The adsorption mechanism probed by X-ray photoelectron spectroscopy showed the presence of sulfate as the only species formed from the oxidation of H 2 S, which was further confirmed by ion chromatography. Thus, the study reports room-temperature oxidation of H 2 S over mixed metal composites, which were synthesized by a novel one-step approach.