Spray a way to better catalysts

Using a technique called ultrasonic spray pyrolysis, researchers at the

have created an improved catalyst for removing smelly sulphur-containing compounds from gasoline and other fossil fuels.

The improved catalyst is a form of molybdenum disulphide, most commonly recognised as the black lubricant used to grease automobiles and machinery.

Molybdenum disulphide is made of long flat layers of molybdenum metal atoms sandwiched above and below by single atomic layers of sulphur. The interactions between sulphur-sulphur planes are weak, so they can easily slide past one another, providing excellent high-temperature lubrication.

Molybdenum disulphide's other important commercial application is as a catalyst used by the petroleum industry to remove ecologically damaging sulphur-containing compounds in gasoline. When burned, these sulphur compounds cause the formation of acid rain.

"The flat planes of molybdenum disulphide that make it a good lubricant also decrease its ability to react with fuels to remove sulphur," said Ken Suslick, the Marvin T. Schmidt Professor of Chemistry at Illinois and a researcher at the Beckman Institute for Advanced Science and Technology. "This is because all the reactions necessary for sulphur removal occur on the edges of the long planes, and the bigger the planes, the less relative edge there is."