Stringent emissions standards with 95+% conversion efficiency requirements call for advanced ceramic catalyst supports with thinner walls, higher cell density and optimum cell shape. The extrusion technology for cellular ceramics has also made significant progress which permits the manufacture of advanced catalyst supports. Similarly, modifications in cordierite chemistry and the manufacturing process have led to improved microstructure from coatability and thermal shock points of view. The design of these supports, however, requires a systems approach to balance both the performance and durability requirements.
Indeed as the wall gets thinner, the contribution of washcoat becomes more significant in terms of thermal mass, heat transfer, thermal expansion, hydraulic diameter and structural stiffness - all of which have an impact on performance and durability. For example, the thinner the wall is, the better the light-off performance will be. Similarly, the higher the cell density is, the better the conversion efficiency will be. However, too thin a cell wall reduces structural strength and too high a cell density increases back pressure.
This paper examines the effect of cell size and shape on durability and performance of advanced ceramic catalyst supports. Such an approach leads to certain trade-offs which must be considered for optimizing the performance and durability of advanced ceramic catalyst supports simultaneously.