Engelhard Corporation is introducing a new platinum/palladium diesel oxidation catalyst (DOC) technology that allows automakers to meet Euro IV emission regulations and also reduce their precious-metal costs.

A diesel oxidation catalyst (DOC) is a flow-through device installed on the exhaust pipe. As exhaust gases pass through it, the catalyst, carbon monoxide, gaseous hydrocarbons and liquid hydrocarbon particles (unburned fuel and oil) oxidize, thereby reducing emissions.

The DOC is essentially a canister containing a honeycomb-like structure or substrate coated with an active catalyst layer usually containing a small, well-dispersed amount of a precious metal such as platinum.

The use of palladium in a DOC is not new. Engelhard has had different implementations of such devices out for years, and International Catalyst Technology (ICT) introduced its own version of a palladium/platinum DOC last year.

But manufacturers are looking to increase the amount used (to reduce cost), while improving the activity of the device to meet increasingly stricter regulations. Palladium in prior applications has extended the thermal life of the device, and improved performance of an aged catalyst, but produced lower activity of a fresh catalyst. 

The Engelhard platinum/palladium diesel oxidation catalyst (DOC) technology enables palladium to be substituted for one-third of the platinum on a light-duty DOC and meet the Euro IV regulations.

The technology goes into serial production starting next month on new model platforms from two major European carmakers.