A series of NiFe mixed oxide catalysts were prepared via calcining hydrotalcite-like precursors for the selective catalytic reduction of nitrogen oxides (NOx) with NH3 (NH3-SCR). Multiple characterizations revealed that catalytic performance was highly dependent on the phase composition, which was vulnerable to the calcination temperature. The MOx phase (M = Ni or Fe) formed at a lower calcination temperature would induce more favorable contents of Fe2+ and Ni3+ and as a result contribute to the better redox capacity and low-temperature activity. In comparison, NiFe2O4 phase emerged at a higher calcination temperature, which was expected to generate more Fe species on the surface and lead to a stable structure, better high-temperature activity, preferable SO2 resistance, and catalytic stability. The optimum NiFe-500 catalyst incorporated the above virtues and afforded excellent denitration (DeNOx) activity (over 85% NOx conversion with nearly 98% N2 selectivity in the region of 210–360 °C), superior SO2 resistance, and catalytic stability.

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The nitrate form of Ni-Al layered double hydroxide (denoted as Ni-Al-NO 3-LDH) and the corresponding carbonate form (denoted as Ni-Al-CO 3-LDH) were tunably fabricated by the hexamethylenetetramine hydrolysis method. A catalytic behaviour investigation proved Ni-Al-CO 3-LDH to be an ineffective catalyst, while for Ni-Al-NO 3-LDH excellent catalytic activity and reusability were obtained, in the acetalisation of furfural to furfural diethyl acetal. Characterisation and analysis revealed that the appearance of Lewis acid sites in Ni-Al-NO 3-LDH was responsible for its excellent catalytic performance. The acquired kinetic parameters confirmed that this reaction was a first-order process and the apparent activation energy was 36.28 kJ mol-1 , which is in reasonable agreement with the theoretical result of 38.57 kJ mol-1. Additionally, apart from the typical Brønsted acid catalytic mechanism, a possible Lewis acid catalytic mechanism was probed theoretically.

Mn‐Fe/ZSM‐5 was prepared via co‐precipitation (CP) and precipitation–chemical vapor deposition (P‐CVD) methods. Catalytic performance investigation showed that Mn‐Fe/ZSM‐5 by P‐CVD method had higher catalytic activity and SO2 resistance than the ones by CP method for NH3‐SCR at low temperature. Characterization results proved that the amount of ammonium sulfate deposited on the surface of Mn‐Fe/ZSM‐5(P‐CVD) was less than that of Mn‐Fe/ZSM‐5(CP) catalyst. Further investigations revealed that the deposition and decomposition of ammonium sulfate proceeded in a dynamic balance on Mn‐Fe/ZSM‐5(P‐CVD) catalyst, which was crucial for the excellent catalytic performances in the presence of SO2 and H2O.