A senior figure at Johnson Matthey has highlighted the role of 'catalytic zoning' in making the company's compact catalytic soot filter far more cost-effective.

The process was developed to meet the requirement of placing special catalysts in specific locations in particulate filters and to place different types of catalyst in different areas.

Chief Scientist Dr Martyn Twigg has explained that the robotic approach - which makes use of a vacuum - has enabled cheaper catalysts such as palladium to be used in sections needing less activity.

He said: "This new process enables precise amounts of nano-sized catalysts on micro-sized, thermally stable materials to be placed in the filter walls at precise locations along its length.

"Being just a single unit, much less manufacturing energy and materials are needed than in previous designs and this, together with its optimised production, makes the [filter] particularly cost-effective."

Dr Twigg also explained that another advantage of the filter is that it is small enough to attach straight onto the turbocharger, which is located in a cramped area of an engine.

As a result, it can help to considerably improve thermal efficiency, while allowing all the exhaust heat to catalytically remove hydrocarbon and carbon monoxide pollutants when on the road.

With the soot being burned in a controlled environment in the filter, the higher thermal efficiency also means that less fuel is required to instigate this process.

New European regulations relating to particulate matter emissions are being phased in during 2009 and applied to all new models from 2010, so Johnson Matthey believes these targets can only be achieved by fitting particulate filters.

The company has already manufactured roughly 2.5 million units of its compact version in Royston and exported them to Europe.

Sources:

Dr Martyn Twigg, The Ingenia Magazine, Issue 38, Mar 2009
http://www.ingenia.org.uk/ingenia/articles.aspx?index=538

Compact diesel filtersEMISSION CONTROL TECHNOLOGIES