Gold - A Future Role in Automotive Pollution Control? 2002-01-2148
Innovative recent research has suggested that gold-based catalysts perform in a manner which could be relevant to their application in the automotive industry. The most likely first use for gold catalysts is for the removal of carbon monoxide impurities from the hydrogen streams used for fuel cells. Absence of carbon monoxide would enable fuel cells to run at lower temperatures and with improved efficiency. Effectiveness in this application has already been demonstrated, and supported gold catalysts are also very active in the water gas shift reaction used for producing hydrogen from carbon monoxide and water. Incorporation of gold into fuel cells could also provide useful conductivity properties, and fuel cell powered vehicles have very low emissions. The use of gold catalysts with diesel engines (passenger car), where the operating temperatures (300-350°C) are lower than petrol engines is also well worth exploration. Another application may be in lowering the light off temperature in future autocatalytic applications.
The new gold catalyst systems, consisting of nanoparticulate gold on oxide supports, can be used to oxidize carbon monoxide at or even below room temperature. Supported gold catalysts are active for the oxidation of methane and propane, and the removal of NOx has also been demonstrated. In exploratory work, a gold on transition metal oxide catalyst system has shown potential as a low temperature three way catalyst - with the light off temperatures lowered for both hydrocarbons and carbon monoxide when fresh catalyst is used.
The relatively low price and greater availability of gold compared with the platinum group metals is discussed, providing additional justification for further investigation of the use of gold catalysts in fuel cells and pollution control applications. Details of World Gold Council and European Commission supported research, that will underpin the potential future use of gold catalysts are discussed.