Left: In John Bercaw’s lab, grad student Seva Rostovtsev conducts a reaction with oxygen and one of the platinum complexes under investigation. Right: John Bercaw, Centennial Professor of Chemistry

Hunting the elusive catalyst

Barbara DiPalma

The importance of John Bercaw’s research isn’t hard to grasp—just think about what it’s cost you lately to fill your car with gasoline. Caltech’s Centennial Professor of Chemistry has a long-standing interest in developing catalysts that will selectively change natural gases—which are probably as abundant on Earth as petroleum—into the chemicals needed to make plastics, solvents, and especially the alternative fuel methanol. The key word is selectively: Bercaw is looking for a catalyst that will let him precisely control the timing of methane-to-methanol conversion.

The giant petrochemical corporation BP thinks Bercaw’s work is important, too—so much so that it recently awarded him, his colleague Jay Labinger, and their research team a 10-year, $10 million grant to figure out how to turn methane gas into more user-friendly chemicals. Ideally, the investigators would like to find a catalyst that would let them combine oxygen with methane to produce methanol, or (even better) ethylene or propylene, chemicals that are used to make a host of everyday products.

Bercaw and his collaborators have their work cut out for them. It’s not difficult to make methane react with oxygen; what’s tricky is stopping the reaction part way, before it ends up as carbon dioxide and water. Unfortunately, the usual way of controlling this reaction—by a two-step process that uses steam to turn methane into carbon monoxide and hydrogen, then makes methanol from those two gases—requires considerable energy, and is thus expensive. It leaves the chemists once again hunting for the elusive catalyst that can do the job in one energy-efficient step.

A compound containing a reactive platinum center may turn out to be that catalyst. Russian researchers have reported using that metal to produce methanol from methane with a high degree of selectivity, and the Bercaw lab has been testing their findings for several years. But difficulties persist: the platinum compound quits working after one reaction cycle, and it’s not easily recycled using oxygen. Bercaw has continued to experiment with the platinum–methane reaction, however, and he now believes he understands the molecular basis for its selectivity. Although there are no guarantees, he thinks there’s a reasonable chance that this work will lead to a more efficient way of making methanol. But a big practical payoff isn’t Bercaw’s primary goal. “My interest in this problem is really in the fundamental chemistry that underlies everything,” he says. “I really enjoy understanding how things work.”

(Note: This article appeared in the Caltech 1999-2000 annual report. For a copy of the report, contact Barbara DiPalma at dipalma@caltech.edu.)
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