11th December 2007

Nanostellar's gold technology for diesel autocatalysts is, rather like the recent announcements by Mazda and Nissan on nanotechnology in autocatalysts, yet another potential route to the goal of all OEMs and catalyst developers, which is to reduce the cost of platinum group metals based catalysts while maintaining their effectiveness in meeting legislated emissions standards.

Gold is a good oxidation catalyst at room temperature but its activity is reduced at higher temperatures and by exposure to traces of sulphur in diesel fuel. This is likely to be the reason why, as reported in the 10/12/07 press release by Nanostellar, their catalyst "uses gold alongside traditional platinum and palladium metals". Platinum has very good activity in the presence of sulphur and at the typical operating temperature of a diesel exhaust. At this stage it is not clear whether Nanostellar's experimental catalyst will meet the demanding performance and durability requirements of today's emissions control laws. 

Catalyst developers such as Johnson Matthey are progressively introducing palladium into diesel catalysts in conjunction with platinum to lower the cost of the emissions system. Palladium is less than half the price of gold, and auto companies are already using this platinum-palladium technology.