Tandem Catalysts Design towards Efficient Selective Catalytic Oxidation of ammonia (TCatSCO)

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Selective catalytic oxidation (SCO) of NH3 to N2 is one of the best ways to eliminate NH3 emissions. A major challenge in NH3-SCO is to achieve high conversion for a wide operating temperature range, avoiding over-oxidation to N2O and N2. The commercial Pt catalysts have full NH3 conversion at low temperatures but suffer from low N2 selectivity. To mitigate this challenge, it is crucial to limit the overoxidation of NH3. The researcher proposes that by integrating highly active Pt with highly selective Cu or Pd, new tandem Pt-CuO/Al2O3 and Pt-Pd/Al2O3 catalysts will form and help improve the N2 formation. The simultaneously high conversion and selectivity can be achieved by modifying the bimetallic catalysts with atomic-level precision. This will change the NH3 adsorption, N-N formation and the O2 activation on the surface, which can be probed via a series of operando spectroscopy, including X-ray absorption fine structure, X-ray emission, Infrared, and electron paramagnetic resonance. The possible intermediates and reaction pathways for internal selective catalytic reduction mechanism and N2- mechanism will be explored with those operando methods combined with density-functional theory calculations. The results are expected to provide a solution towards the upcoming Euro-7 regulations, which are valid from 2025 onwards for NH3 emissions.