When natural gas is discovered at remote oil drilling sites, it is typically burned off or pumped back into the ground, because shipping the gas costs more than it's worth. Now researchers have developed a new catalyst that converts methane, the chief component of natural gas, into a liquid fuel that can easily be transported by tankers and trucks. By doing so, the new catalyst, reported in tomorrow's Science, could help companies tap the vast natural gas reserves around the world.
Converting methane to methanol is easy: just strike a match. At about 625 degrees Celsius, molecules of methane, each made up of a carbon atom bound to four hydrogens, begin to burn with oxygen displacing the hydrogens. Methanol is one of the first byproducts. But the trouble is that once methane begins to burn, "you can't stop that reaction," says Roy Periana, a chemist at Catalytica Advanced Technologies in Mountain View, California. In no time, oxygen atoms oust all the hydrogens, leaving worthless carbon dioxide. The trick is to stop the process in midburn.
In the mid-1980s, researchers first discovered that some organic compounds laced with metal could manage this feat. The problem was that less than 2% of the methane was converted. In 1993, Periana and his colleagues discovered a mercury-based compound that did much better, converting about 40% of methane to a derivative of methanol. But since mercury is toxic, the researchers kept hunting for a better solution. The new catalyst, based on nontoxic platinum, is the best yet: It transforms 70% of methane to methyl bisulfate, which is easily converted to methanol.
"This is a major breakthrough," says Jay Labinger, a chemist at the California Institute of Technology in Pasadena who has worked on similar catalysts. But Labinger and others say it's still too early to tell if the new catalyst will take off commercially. Transforming methyl bisulfate to methanol requires extra steps that may cost too much on an industrial scale, says Labinger.