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Quicker Catalysts
by Angela Spivey

To get things going, sometimes scientists need a catalyst—a chemical compound that speeds up a chemical reaction. Finding more efficient catalysts can help improve all kinds of processes, such as harvesting solar energy or making drugs or plastics. But designing the right one and perfecting it usually takes years. Not anymore, though—two Carolina researchers have invented a way to pinpoint effective catalysts in a fraction of that time.

Traditionally, creating catalysts is a time-consuming process of trial and error, says James Morken, assistant professor of chemistry. First, you combine two or three chemicals. Then you test the new catalyst to see if it will speed up a reaction. If it doesn't, you use a different variation of each chemical, then test the compound again.

But Morken and doctoral student Steven Taylor skip all that. Using a method called "combinatorial chemistry," they mix chemicals in thousands of different combinations, then use a chemical process to permanently attach each potential catalyst to a tiny bead made of polystyrene—the same stuff that makes up Styrofoam cups. They put the beads into a container with a chemical solution, then look at them all at once using a thermographic video camera, which measures heat. The compounds that show up are the hot ones—those causing a reaction in the solution and thereby generating heat. The chemists fish out these "hot beads" and test them further. Most of the time, those reactive compounds turn out to be the best catalysts.

So far the researchers have used this method to screen 3,150 potential catalysts. They expect that number will soon increase. "We can make 100,000 compounds in two weeks," Morken says, "and we can screen those in about one hour."

This method is quick because the scientists try all variations of the chemical compounds at once, rather than first trying to predict which ones will work. "We're admitting that we don't know everything there is to know about designing catalysts," Morken says. "Some researchers believe that using combinatorial chemistry is unscientific. But it's a quick, efficient way to find effective catalysts. The science comes in studying what makes them so effective."

A report on this research appeared in the April 10 issue of the journal Science.