Sweets spur biodiesel reaction

A Japanese research team has created an environmentally friendly catalyst for producing biodiesel, an alternative fuel, from renewable sources. The new catalyst is mainly charred sugars.

Biodiesel production typically begins with vegetable oil and an alcohol. A catalyst converts these ingredients into fatty acid alkyl esters, the compounds that constitute biodiesel. The most widely used catalysts are bases, such as sodium hydroxide, that convert 98 percent of the starting materials into the esters.

Using a chemically basic catalyst, however, requires additional costly steps, says Michikazu Hara of the Tokyo Institute of Technology. The biodiesel must be neutralized with an acid and then purified of the basic catalyst’s remains.

Hara’s team set out to make a catalyst that could be more easily separated from the fuel. The starting material was either sucrose or glucose. The researchers burned a sugar at 400°C and then heated it in sulfuric acid at 150°C, which added reactive sites. The resulting black powder, a form of carbon rich in molecular-ring structures, could be shaped into pellets or thin films.

The researchers recovered the prototype catalyst by simply decanting the biodiesel, they report in the Nov. 10 Nature. They used the catalyst repeatedly and reported no loss in its activity.

Though easy to employ, the sugary catalyst converted only 20 percent of the starting material into biodiesel fuel. But it may be possible to increase the catalyst’s efficiency by increasing the temperature of the biodiesel reaction, says Hara.