Washington: Chemists have discovered that the expensive platinum catalyst that cleans diesel-car exhaust fumes can be replaced with cheaper materials, a finding that may lower the cost of fuel-efficient engines, including those in petrol vehicles — making it easier for carmakers to meet tougher emissions standards.
According to a report in Nature News, a team led by Wei Li at General Motors research and development labs in Warren, Michigan, US, has shown that oxides of the common mineral ore perovskite — fortified with the metals strontium and palladium — perform better than platinum at cleaning up the exhaust emissions of ‘lean-burn’ combustion engines.
Cars with these engines emit fewer greenhouse gases and consume less fuel per kilometre than petrol vehicles, but tend to be more expensive.
Jim Parks, who works on fuel emissions and catalysts at Oak Ridge National Laboratory, Tennessee, said that if platinum could be eliminated from diesel catalysts, “the difference in price may be relatively small at first; perhaps US 100 dollars – 400 dollars depending on the size of the vehicle”.
But, the more important point of this latest technology is that it could allow car manufacturers to consider using lean-burn engines in petrol cars, as they try — or are forced by legislation — to increase the fuel economy of their vehicle fleet.
“We are now working on tests with real vehicles. It’s hard to predict when this will make it into commercial production — but perhaps in a few years,” said Li.
“The strontium is the secret,” said Li — although exactly what it is doing is unclear.
He speculated that it may help oxygen atoms bind to the catalyst during the crucial oxidation step.
David Jollie of the London-based chemicals group and catalyst manufacturer Johnson Matthey sees the improvement as exciting, but just “one more potential tool” to improve fuel economy.