Tuning the selectivity of NH<sub>3</sub> oxidation via cooperative electronic interactions between platinum and copper sites.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39746963.
- Also identified by DOI 10.1038/s41467-024-54820-y and PMC identifier 11697224.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Selective catalytic oxidation (SCO) of NH<sub>3</sub> to N<sub>2</sub> is one of the most effective methods used to eliminate NH<sub>3</sub> emissions. However, achieving high conversion over a wide operating temperature range while avoiding over-oxidation to NO<sub>x</sub> remains a significant challenge. Here, we report a bi-metallic surficial catalyst (Pt<sub>S</sub>CuO/Al<sub>2</sub>O<sub>3</sub>) with improved Pt atom efficiency that overcomes the limitations of current catalysts. It achieves full NH<sub>3</sub> conversion at 250 °C with a weight hourly space velocity of 600 ml NH<sub>3</sub>·h<sup>-1</sup>·g<sup>-1</sup>, which is 50 °C lower than commercial Pt/Al<sub>2</sub>O<sub>3</sub>, and maintains high N<sub>2</sub> selectivity through a wide temperature window. Operando XAFS studies reveal that the surface Pt atoms in Pt<sub>S</sub>CuO/Al<sub>2</sub>O<sub>3</sub> enhance the redox properties of the Cu species, thus accelerating the Cu<sup>2+</sup> reduction rate and improving the rate of the NH<sub>3</sub>-SCO reaction. Moreover, a synergistic effect between Pt and Cu sites in Pt<sub>S</sub>CuO/Al<sub>2</sub>O<sub>3</sub> contributes to the high selectivity by facilitating internal selective catalytic reduction.