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

In high temperature combustion processes involving air and a fuel, such as power generation and internal combustion engines, NO_x is emitted with terrible consequences for the climate and the environment. Selective catalytic reduction (SCR) is currently used in the abatement of NO_x in heavy vehicles, marine engines and stationary power plants. In the SCR process, the reductant (i.e., gaseous ammonia, NH₃) converts NO into N₂ and H₂O completely when one or more molecules of NH₃ per NO are introduced. As a consequence, some of the excess of ammonia will be emitted!

*The majority of SCR system consists of a monolithic honeycomb catalyst (left image) of vanadium oxide (V2O2) active phase supported on WO3-TiO2 or MoO3-TiO2 oxides (right image).*

About the project

We aim at developing a high performance catalyst that quantitatively can remove an excess of ammonia (in trace amounts) that has deliberately been co-fed as the active reductant in NO_x abatement. By adding an ammonia slip catalyst to the process one can use an excess of reductant up-stream of the SCR unit allowing for complete reduction of NO_x while the processed gases will thereafter enter the ammonia slip stage of the system where the excess ammonia is decomposed. High activity at low-temperatures and tolerance to sulphur poisoning are fundamental criteria when developing novel materials for the slip catalyst. Metallic PGM nanoparticles (mainly Pt, Rh) and transition metal oxides (TOM’s), whose synthesis are well established at UiO, are the best candidates. Properties and performance of these novel materials will be investigated through surface-sensitive techniques: advanced home laboratories (RECX and reactor STM at UiO) and synchrotron radiation facilities (SNBL@ESRF) provide excellent opportunities for time and space resolved studies of catalysts during work at realistic conditions (operando methods).

Objectives

Primary objective

To understand the activity of metal-on-support catalysts on an atomistic basis, and develop breakthrough (nano) materials that open for high-level NO_x abatement in combination with current basic SCR technologies.

Secondary objectives

Establish in-depth understanding for ammonia oxidation on various metal-on-support catalyst systems by means of in-situ (in-operando) studies with the goal to tune selectivity towards nitrogen and water in the following reaction scheme: 4NH₃(g) + 5O₂(g) → 2N₂(g) + 6H₂O(g).
To develop highly reactive PGM based metallic nanoparticles for NH₃ oxidation.
To develop highly reactive transition metal oxides capable to undertake NH₃ oxidation.
Establish lab scale experimental facilities for studies of interaction of ammonia molecules with PGM surfaces by means of reactor-STM.
Expand the network of international cooperation, educate PhD and postdoc candidates, and disseminate the results through publications and collaboration with Norwegian industry.

Outcomes

Understanding chemistry and catalytic activity, along with preparation of novel, highly improved ammonia slip catalyst, can form the basis for a great advance in SCR technology. A combination of SCR and ammonia slip catalysts may form the future BAT (Best Available Technology) for driving NO_x emission limits lower and represents a component that easily can be translated into value creation by the industrial partners.