A team of Japanese researchers have devised a low-cost and ecologically friendly solid catalyst for the production of biodiesel. The new catalyst can be produced from sugar, starch or cellulose and is designed to replace the common but more costly and wasteful use of a liquid acid catalyst in the refining of biodiesel.
The research team, from the Tokyo Institute of Technology, the National Institute of Advanced Industrial Science and Technology, and the University of Tokyo reported their findings in the November 10th issue of Nature this week.
According to the Nature report, the production of biodiesel through the esterification of higher fatty acids requires an efficient catalyst. The esterification of is typically performed "by liquid acid catalysts such as sulphuric acid (H2SO4) ... but it involves high consumption of energy and the separation of the catalysts from the homogeneous reaction mixtures is costly and chemically wasteful. Recyclable solid acids, such as Nafion, make better catalysts, although they are also expensive and their activity is less than that of liquid acids."
The researchers took a new approach and devised a mechanism that "overcome[s] these problems by sulphonating incompletely carbonized natural organic material to prepare a more robust solid catalyst." According to the researchers, "Incomplete carbonization of natural products such as sugar, starch or cellulose results in a rigid carbon." This process is "expected to generate a stable solid with a high density of active sites, enabling a high-performance catalyst to be prepared cheaply from naturally occurring molecules." The researchers found that the activity of their solid sulphonated carbon catalyst is more than half that of a liquid sulphuric acid catalyst, and much higher than that achieved by conventional solid acid catalysts.
Although their initial report focuses on sugar, they have also successfully prepared catalysts identical in function from carbonized starch and cellulose.
The researchers also claim that "in addition to biodiesel production, such environmentally benign alternative catalysts should find application in a wide range of other acid-catalyzed reactions.
Finally, according to the report, the new catalyst materials are recyclable and "fully ecologically friendly."
[A hat tip to Green Car Congress]