Two Brown chemists have developed a more efficient way to produce biodiesel from waste vegetable oil.
Using two catalysts common in organic chemistry, Assistant Professor of Chemistry Jason Sello and Postdoctoral Fellow Aaron Socha were able to synthesize biodiesel in a single reaction vessel, according to a University press release. Their findings were published in the Oct. 7 issue of the journal Organic and Biomolecular Chemistry.
Traditional methods of synthesizing biodiesel from waste oil require two reaction vessels. The method developed by Sello and Socha is six times faster than current methods, consumes less energy overall and is more environmentally friendly, according to the release.
"We wanted to do research that had implications for alternative energy, and biodiesel is certainly an attractive area," Sello said.
Sello said he and Socha began their research in the middle of 2009. Their research was accepted by the journal on July 19 and was published online "almost immediately," he said.
The biodiesel conversion requires one reaction to convert free fatty acids to biodiesel and another to convert triacylglycerols to biodiesel. The former is traditionally catalyzed by sulfuric acid, and the latter by potassium hydroxide or sodium hydroxide. The reactions must be performed separately or else the acid and base yield soaps.
In developing the new procedure, the chemists considered catalysts that could complete the reaction in a single vessel and that were readily available, low in cost, low in toxicity and stable in the presence of water and air that might be in the waste oil after cooking. They opted to use bismuth triflate and scandium triflate, in part because bismuth was relatively cheap and his lab had experience with scandium, Sello said.
When the catalysts did not yield biodiesel under standard conditions, Socha suggested using a microwave reactor. Socha said there were "not many but (still) a few" papers that set some precedent for using a microwave reactor.
The combination of the two catalysts and the microwave reactor successfully yielded biodiesel at 150 degrees Celsius. After demonstrating a successful yield, the researchers sought to minimize the temperature, the amount of catalyst and the time needed for the reactions. Sello said they also tested "every possible component of waste vegetable oil" to verify that the reaction would still be successful.
The catalysts in the free fatty acid reaction can be recycled up to five times while still obtaining a 97 percent yield, according to the press release.
Two external grants supported the research. The National Science Foundation provided Sello with a grant for $170,000. Socha's fellowship, awarded by the American Competitiveness in Chemistry, is also funded by the NSF, with $200,000 split over two years. Sello said the University's $15,000 R.B. Salomon award also funded several projects, including this research.
"We often think about organic chemistry in terms of making drugs, but this is a very nice demonstration that organic chemistry has applications even in alternative energy," Sello said. "It really does highlight the power of organic chemistry."
Few scientists are researching biodiesel synthesis in an academic setting, Sello and Socha said, which is why they think nobody else had tried this approach before. Additionally, chemical engineers who look at biodiesel do not necessarily know all the current catalysts being used in organic chemistry, Sello added.
"In principle, anyone could have done this, but I think we were just in a unique position just given our perspective here," Sello said.
Sello said that the report in the journal was simply on "an academic scale" and that he and Socha have not yet started testing the chemistry on an industrial scale. Socha said that until the price of biodiesel becomes competitive with the price of oil, biodiesel cannot become "the next fuel."
Socha said that he is "not really jumping at the opportunity to commercialize this" yet because of the other advances needed before biodiesel becomes usable on a large scale. But he said he does plan to file a patent disclosure.
