CleanUp Technologies: Oxidation Catalysts

Oxidation catalysts are fitted to all new diesel passenger cars and car based vans in Western Europe, over 3 million per annum. These devices will also be fitted to light duty trucks from now on. Emissions reductions of up to 90% for carbon monoxide (CO), 90% for hydrocarbons (HC) and 25% for particulates (PM) may be expected.

Oxidation catalysts are used for light duty vehicles where particulate traps may not be suitable due to the lower operating temperature (light load / low speed). On heavy duty vehicles, they are equally effective, especially on older engines with poor oil control where the sulphur content of the oil in the exhaust may diminish the trap's catalytic action; in these applications, up to 50% particulate
reduction has been noted.

The device typically consists of a stainless steel canister that contains a honeycomb-like structure providing a large surface area coated with precious metals and a special washcoat which acts to promote chemical reactions transforming pollutants into harmless gases by oxidation, i.e. breaking
the pollutant down to oxides as follows:

• Carbon monoxide (CO) becomes carbon dioxide (CO2)
  
• Hydrocarbon (HC) molecules become water (H2O) and carbon dioxide (CO2)
  
• The particulate (Pm) reduction is effected by stripping off the HC components (fuel and lubrication oil derived) from the soot kernel and oxidised

Oxidation catalysts require no maintenance. CleanUp is now trialling oxidation catalysts on taxis and light duty trucks.