Success in this business is dependent on four factors:
- washcoat technology to meet increasingly stringent emission standards at decreasing costs
- strong customer relationships
- the ability to meet individualized OEM customer requirements through applied technology efforts during the bidding and pre-production phases
- efficient and reliable manufacturing during the mass production phase.
Structure of a catalyst
An exhaust gas catalyst consists of several components:
- the substrate
- The washcoat
- The precious metals
- The canning
Typically high temperature stable honeycomb structures are made from cordierite or metal. The cell density can vary between 200 up to 1200 cells per square inch, the wall thickness between 3 and 12 mil. The small channels are coated with one or more oxidic slurry which is either precious metal free or already contains the precious metals.
The washcoat contains catalytic active materials and are mixed in an aqueous slurry for application to the substrate. . Depending on the reaction that should be enhanced with the catalyst, these active materials vary. For example, for Three-Way catalysts, OSC material plays a critical role, while for SCR catalysts, the choice of the right zeolite material is essential.
The precious metals
Umicore designs technologies to meet the needs of the specific PGM in use. Often Rh is combined with Pt or Pd to create a bi-metallic catalyst and sometime all three are used as a tri-metal catalyst. The proper selection depends upon the specific requirements of the application and customer.
The finished part is then fixed with an insulating mat and is put into a so-called can – a metal housing which is part of the exhaust pipe. The exhaust pipe contains lambda sensors that guarantee optimum lambda window operation to avoid overheating of the catalyst.