Understanding and Tailoring activity of an Ammonia Slip CATalyst (ASCAT) - Operando STM (completed)

A technology that meets the challenge of zero NOx release from the diesel powered transport sector is lacking. We work on a new concept (see Figure below) dedicated to this vison, which involves the following steps:

  1.  a Selective Catalytic Reduction (SCR) catalyst over which NOx is reduced to nitrogen in excess ammonia;
  2.  oxidation of unreacted ammonia to nitrogen. Adding the second step allows for complete NOx reduction and prevents release of NH3.

Focusing on the step 2., we are developing a next generation ammonia oxidation catalyst, based on bimetallic noble metal alloys, which selectively oxidizes ammonia to N2 (and not N2O and NO) at 200-400 °C and at ambient pressure.

Schematic representation of the model catalytic system for the ammonia oxidation step (right), composed of Rh-Pt on a Pt(111) single crystal. Unreacted ammonia, arriving from the SCR stage is oxidized by O2 to yield N2 and possibly also undesired by-products like NO and N2O.

Preliminary results

STM of bimetallic Rh-Pt/Pt(111) model catalyst surface as prepared and annealed to 600-900K. Prepared at room temperature, small, homogeneously dispersed single and double layered triangular clusters upon annealing above 600K grow into larger single layered hexagonal islands, mixing and alloying with Pt at the step edges and terraces. 

Tools

Publications

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  • Ivashenko, Oleksii; Pettersen, Christine; Johansson, Niclas; Jensen, Martin; Schnadt, Joachim & Sjåstad, Anja Olafsen (2021). How surface species drive product distribution during ammonia oxidation: an operando APXPS Study.
  • Ivashenko, Oleksii & Sjåstad, Anja Olafsen (2018). Role of Rhodium in RhPt catalysts for ammonia oxidation revealed by operando STM and NAP-XPS.
  • Sjåstad, Anja Olafsen (2018). Bimetallic PtRh catalysts for intermediate temperature ammonia oxidation - Combining traditional catalysis with surface science.
  • Ivashenko, Oleksii; Zheng, Jian; Johansson, Niclas; Groot, Irene M.N.; Schnadt, Joachim & Sjåstad, Anja Olafsen (2018). Role of Rhodium in RhPt catalysts for ammonia oxidation revealed by operando STM and NAP-XPS.
  • Ivashenko, Oleksii; Zheng, Jian; Fjellvåg, Helmer & Sjåstad, Anja Olafsen (2017). Operando Investigations of Surfaces for NOx Abatement Catalysis.
  • Sjåstad, Anja Olafsen; Zacharaki, Eirini; Bundli, Silje; Jensen, Martin; Kalyva, Maria Evangelou & Dhak, Prasanta [Show all 10 contributors for this article] (2017). Nanoparticles for heterogeneous catalysis of industrial relevant processes.
  • Zheng, Jian; Ivashenko, Oleksii; Sjåstad, Anja Olafsen & Groot, Irene M.N. (2017). XPS and STM characterization of Pt(111) and PtRh/Pt(111) NH3 slip catalysts for NOx abatement. 6th National Meeting On Inorganic And Materials Chemistry.

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Published Oct. 12, 2017 4:59 PM - Last modified Mar. 10, 2023 11:24 AM

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