Influence of preparation conditions to structure property, NOx and SO2 sorption behavior of the BaFeO3 − x perovskite catalyst

A series of the BaFeO3 − x perovskite catalysts was synthesized by a sol-gel method using citric acid and/or EDTA as complexants with a purpose to improve their sulfur-resistance by forming a uniform perovskite structure at a low calcination temperature, i.e. 750 °C. The thermogravimetry results show that almost no carbonate was formed after calcination of the xerogel precursor with the complexants' molar ratio of CA/EDTA ≤ 1.5, which was convinced by the in situ DRIFT spectra results of the Ba–Fe-1 catalyst during the SO2/O2 sorption. It indicates that, after adding EDTA into the complexants, the metal ions of the raw material could be mixed homogeneously and react stoichiometrically by calcination at 750 °C to form a uniform perovskite structure. Accordingly, the obtained Ba–Fe-1 perovskite presented a performed sulfur-resistance. Moreover, the seriously damaged structure of the BaFeO3 − x perovskite by reduction could be in situ regenerated by calcination under lean conditions at 400 °C, which is within the operating temperature zone of the aftertreatment system of diesel to meet the real commercial demands.

Research highlights
► The BaFeO3 − x perovskite was prepared by a sol-gel method.
► The BaFeO3 − x perovskite was used as a NOx storage-reduction catalyst.
► Addition of EDTA made the metal ions mix homogeneously in the sol.
► Complexants with CA/EDTA ≤ 1.5 could produce a uniform perovskite structure.
► The uniformed BaFeO3 − x perovskite has a good sulfur-resistance.