Ammonia Slip CATalysts (ASCAT)- Operando STM

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. 

Collaboration

Ass.Prof. Irene M. N. Groot (University of Leiden, NL)

Tools

Published Oct. 12, 2017 4:59 PM - Last modified Nov. 14, 2017 3:14 PM