Wolfgang Held

Lean-Burn Catalysts from the Perspective of a Car Manufacturer. Early Work at Volkswagen Research

Lean burn engines offer significantly better fuel economy and also lower engine out emissions of gaseous pollutants than engines tuned to stoichiometric air-fuel ratio. However, the high oxygen excess in the exhaust prohibits the use of the 3-way-catalyst technology for further NOx reduction. New catalytic processes and catalyst materials had to be developed for NOx aftertreatment, to ensure that diesel engines and lean burn DI gasoline engines can comply with very stringent exhaust emissions standards. The paper describes the start and some aspects of the history of that development, from the viewpoint of a car company.

High-performance ceramic substrates for catalytic converters

Higher performance requirements for exhaust gas aftertreatment systems for passenger cars have led to the development of high cell density substrates with walls thinner than a human hair. Whereas the majority of these substrates have a square cell geometry, the potential for further emission improvements has been predicted for hexagonal cell structures. In order to verify these predictions, Corning has developed a ceramic substrate that combines the features of high cell density, ultra-thin cell walls and hexagonal cell geometry. The emission tests were conducted by Volkswagen, who compared the new substrate concept with square cell ceramic substrates.