More stringent emissions regulations, space limitations for catalytic converters in modern automotive applications, and new engine technologies constitute design challenges for today's engineers. In that context high cell density thinwall and ultrathinwall ceramic substrates have been designed into advanced catalytic converters.
Whereas the majority of these substrates have a square cell geometry, a potential for further emissions improvement has been predicted for hexagonal cell structures. In order to verify these predictions, a ceramic substrate has been developed combining the features of high cell density, ultrathin cell walls, and hexagonal cell structure.
Based on modeling data, the actual cell density and wall thickness of the hexagonal cell substrate will be defined. The performance of that substrate will be assessed by comparing experimental emissions results using two modern Volkswagen engines. The emissions of a Euro IV 1.4L FSI gasoline direct injection engine will be presented, comparing the hexagonal cell substrate with the series converter system, a 600/4 [cpsi/mil] ceramic substrate with NOx-adsorbing coating. A second set of tests will provide emissions data of a pre-development SULEV converter system for a 2.0L MPI gasoline engine. Here, the hexagonal cell substrate will compete against a 900/2 ultrathinwall ceramic substrate.