Posted on 03/26/2010 12:19:17 AM PDT by neverdem
Researchers in the US have shown that perovskites - a class of mixed oxide minerals - can perform as well as platinum in certain types of catalytic converter for removing pollutants from diesel exhaust. The finding could eventually result in cheaper, more robust catalytic converters for diesel engines that do not rely on expensive and scarce platinum group metals.
Vehicle exhaust is a major polluter
|
The oxidation of NO to NO2 requires a platinum group metal catalyst, as does the fuel-enriched reduction cycle, where the hydrocarbons are oxidised to eliminate oxygen from the exhaust to allow the reduction step. These metals are, however, costly and scarce. Now, a team of scientists at General Motors Global Research and Development in Michigan has shown that catalysts based on the perovskite oxides La1-X SrXCoO3 and La1-xSrxMnO3 can convert NO to NO2 in simulated diesel exhaust as efficiently as platinum. The oxides are, says team member Wei Li, very simple to manufacture and process and are far cheaper and more durable to heat than their platinum counterparts.
The new catalysts are less efficient at oxidising hydrocarbons and are prone to 'sulfur poisoning' - deactivation by the presence of sulfur in the fuel. However, the research team found that the presence of palladium helped alleviate these problems.
Li says that the team is working to clarify precisely how the catalyst works, and in the meantime will study the its performance in real diesel exhaust.
Justin Hargreaves, a catalyst expert from the University of Glasgow in the UK, describes the research as 'a very interesting piece of work.' Hargreaves adds, 'The observation that the perovskite catalysts studied exhibit higher activity than commercial platinum-based catalysts under realistic screening conditions istechnologically significant, as is the application of perovskite systems combined with palladium for lean NOx trap catalysis.'
Lanthan and Palladium are not a bargain either.
Or we could stop pretending that there shouldn’t be any effect from industry and transportation and stop worrying about vehicle exhaust like it was VX or something similar.
Not according to truckers that drive in the Deep South.
There's a particular kind of bug that is impossible to remove with any conventional windshield cleaner.
Their remedy? Coca-Cola. Seriously.
Safer nuclear reactors could result from Los Alamos research (healing power)
Iowa State NWRC study finds flaxseed lowers high cholesterol in men
Beta-blockers 'cut cancer spread'
FReepmail me if you want on or off my health and science ping list.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.