New Technology For Purifying Exhaust Gas From Diesel Engines

ScienceDaily (Feb. 9, 2009) — An increasing proportion of the Danish vehicle fleet consists of diesel vehicles. In urban areas diesel vehicles are causing air pollution (from carbon particles, nitrogen oxides (NOX)) and unburned hydrocarbons). As the European legislation tightens the rules for emissions, it will become more difficult and expensive to meet the requirements for particulate filters and DeNOx technologies.

A new four-year project at Risø DTU is going to develop an effective method for purifying flue gases, especially exhaust gases from diesel engines. The project has received DKK 17 million from the Danish Council for Strategic Research (the Programme Commission on Sustainable Energy and Environment).

Electrochemical flue gas purification

Existing solutions to air pollution require the installation of particulate filters and either an SCR catalyst (Selective Catalytic Reduction) a NOx absorber or recirculation of the exhaust gas. This leads to additional expenditure when modifying diesel vehicles to be less polluting.

Electrochemical flue gas purification has a number of advantages over existing filters making it attractive to target this research at the car industry. Purification of carbon particles, toxic nitrogen oxides (NOX) and unburned hydrocarbons from the exhaust can all happen in the same filter unit.

Another advantage of using electrochemical methods is that it is not necessary to add other substances to the fuel. In addition the filter can be produced without the use of precious metals. The current SCR technology typically uses the nitrogen-containing urea as a reducing agent to remove NOx from the exhaust.

The purification of exhaust gas will therefore be conducted independently of the engine operation. This technology could lead to significant fuel savings compared with leading alternative technologies. The technology could also be applied in the purification of flue gas from power plants, and possibly in the shipping industry.

Expansion of the research group

The ambitious research project will involve the employment of five PhDs and two postdocs in the near future. Together with the present research team they are going to further develop the technology into a successful prototype for use under realistic conditions in a diesel engine.

The project is led by Kent Kammer Hansen, Senior Scientist in the Fuel Cells and Solid State Chemistry Division at Risø National Laboratory for Sustainable Energy, the Technical University of Denmark. Also participating in the project are the Department of Mechanical Engineering at DTU and the company Dinex Emission Technology A / S.