Engineers at a company co-founded by a University of Texas at Dallas professor have identified a material that can reduce the pollution produced by vehicles that run on diesel fuel. The material, from a family of minerals called oxides, could replace platinum, a rare and expensive metal that is currently used in diesel engines to try to control the amount of pollution released into the air.
In a study published in the August 17 issue of Science, researchers found that when a manmade version of the oxide mullite replaces platinum, pollution is up to 45 percent lower than with platinum catalysts.
"Many pollution control and renewable-energy applications require precious metals that are limited – there isn't enough platinum to supply the millions and millions of automobiles driven in the world," said Dr. Kyeongjae "K.J." Cho, professor of materials science and engineering and physics at UT Dallas and a senior author of study. "Mullite is not only easier to produce than platinum, but also better at reducing pollution in diesel engines."
For the environmentally conscious, the higher fuel efficiency of diesel engines makes an attractive alternative to engines that run on gasoline. On the flip side, compared with gasoline engines, diesel vehicles produce more nitric oxide (NO) and nitrogen dioxide (NO2), which are known as NOx pollutants.
In June, the World Health Organization upgraded the classification of diesel engine exhaust as carcinogenic in humans, putting it in the same category as cigarette smoke and asbestos. Countries throughout the world have drafted guidelines to reduce diesel air pollution in the next decade.
Platinum, because of its expense to mine and limited supply, is considered a precious metal. Estimates suggest that for every 10 tons of platinum ore mined, only about one ounce of usable platinum is produced.
"Our goal to move completely away from precious metals and replace them with oxides that can be seen commonly in the environment has been achieved," Dr. Cho said. "We've found new possibilities to create renewable, clean energy technology by designing new functional materials without being limited by the supply of precious metals."