High and stable catalytic activity of Ag/Fe₂O₃ catalysts derived from MOFs for CO oxidation

In this paper, highly active Ag/Fe₂O₃ catalysts derived from MIL-100(Fe) were synthesized by a traditional wet impregnation method. The catalysts were characterized by N₂ adsorption-desorption, X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM), H₂-temperature program reduction (H₂-TPR) and X-ray photoelectron spectroscopy (XPS). The effects of Fe/Ag ratios and pretreatment atmosphere on the structure and catalytic activity for CO oxidation of Ag/Fe₂O₃ catalysts were investigated. It was found that rarefied oxygen environment in a muffle furnace was beneficial to the formation of small size Ag⁰ species and larger specific surface area, which could be due to the reductive gases (H₂) produced by the decomposition of MIL-100(Fe) and nitrate. The Ag/Fe₂O₃ catalyst with Fe/Ag atomic ratio of 15 calcined in a muffle furnace showed a high catalytic performance (T₁₀₀ = 160 °C), stability and reproducibility, which could be related to the large number of Ag⁰ species on the surface and larger specific surface area. In addition, the effect of water vapor on catalytic activity was also studied. The activity of Ag/Fe₂O₃ catalyst with Fe/Ag ratio of 15 was slightly affected by the 1 vol.% moisture in the feed gas, but still show high catalytic activity with T₁₀₀ = 190 °C.