NO x Removal by Selective Catalytic Reduction with Ammonia over a Hydrotalcite-Derived NiFe Mixed Oxide

摘要

A series of NiFe mixed oxide catalysts were prepared via calcining hydrotalcite-like precursors for the selective catalytic reduction of nitrogen oxides (NO x ) with NH 3 (NH 3 -SCR). Multiple characterizations revealed that catalytic performance was highly dependent on the phase composition, which was vulnerable to the calcination temperature. The MO x phase (M = Ni or Fe) formed at a lower calcination temperature would induce more favorable contents of Fe 2+ and Ni 3+ and as a result contribute to the better redox capacity and low-temperature activity. In comparison, NiFe 2 O 4 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 SO 2 resistance, and catalytic stability. The optimum NiFe-500 catalyst incorporated the above virtues and afforded excellent denitration (DeNO x ) activity (over 85% NO x conversion with nearly 98% N 2 selectivity in the region of 210–360 °C), superior SO 2 resistance, and catalytic stability.