Unraveling Excellent Performance in NH<sub>3</sub>-SCR over Cr-Doped NiMn-LDO Catalysts: A Combined Experimental and Computational Study.

Luan, Xinru; Zhai, Yujia; Guo, Yingying; Liu, Wei; Zhang, Jian; Wang, Liguo; Wang, Zhongpeng · Nano Lett · 2025

basic_science · Level V

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Abstract

A sequence of Cr-doped NiMnO<sub><i>x</i></sub> layered double oxide catalysts was synthesized through coprecipitation and applied in selective catalytic reduction of NO with ammonia (NH<sub>3</sub>-SCR). The catalytic performance for NO reduction was enhanced by tuning the Ni/Mn/Cr molar ratios of the Ni<sub>1</sub>Mn<sub>1</sub>Cr<sub><i>x</i></sub>-LDO precursors (<i>x</i> = 1, 2, 3); notably, Ni<sub>1</sub>Mn<sub>1</sub>Cr<sub>2</sub>-LDO achieved over 90% NO conversion and N<sub>2</sub> selectivity within the temperature range of 150-300 °C. Moreover, Ni<sub>1</sub>Mn<sub>1</sub>Cr<sub>2</sub>-LDO demonstrated significant resistance to SO<sub>2</sub> and H<sub>2</sub>O along with exceptional stability. From the results of the characterization of the physicochemical properties of the catalysts, the presence of Cr species in Ni<sub>1</sub>Mn<sub>1</sub>Cr<sub><i>x</i></sub>-LDO may enhance the surface acidity and reducibility. Additionally, higher amounts of Mn<sup>4+</sup>, Ni<sup>3+</sup>, Cr<sup>3+</sup>, and surface-adsorbed oxygen species were detected on the Ni<sub>1</sub>Mn<sub>1</sub>Cr<sub>2</sub>-LDO catalyst. Through in situ DRIFTS experiments, the promotion of the NH<sub>3</sub>-SCR process on Ni<sub>1</sub>Mn<sub>1</sub>Cr<sub>2</sub>-LDO was confirmed to involve a combination of Langmuir-Hinshelwood and Eley-Rideal mechanisms.