Old tyres and cooking oil combine to produce biofuel

Scientists from an Oak Ridge National Laboratory-led research team have developed a simple method to convert used cooking oil into biofuel. Bizarrely, the system uses reusable carbon material derived from old rubber tyres.

The Oak Ridge team’s approach combines modified, recovered carbon with sulphuric acids, which is then mixed with free fatty acids in household vegetable oil to create usable biofuel.

Scientists from Wake Forest University and Georgia Institute of Technology also worked on the research.

“Many inexpensive biofuel feedstocks, including those containing free fatty acids (FFAs) in high concentrations, are typically disposed of as waste due to our inability to efficiently convert them into usable biofuels,” the authors write in the abstract to their study, published in the journal Chemistry Select. “Here we demonstrate that carbon derived from waste tires could be functionalized with sulfonic acid (-SO3H) to effectively catalyze the esterification of oleic acid or a mixture of fatty acids to usable biofuels.”

It is hoped the research will provide a route to inexpensive, environmentally benign and high-value-added waste-tire derived products, and a step towards large scale biofuel production.

“Waste tires were converted to hard carbon, then functionalized with catalytically active -SO3H groups on the surface through an environmentally benign process that involved the sequential treatment with L-cysteine, dithiothreitol, and H2O2,” the study abstract explains.

“When benchmarked against the same waste-tire derived carbon material treated with concentrated sulfuric acid at 150 °C, similar catalytic activity was observed. Both catalysts could also effectively convert oleic acid or a mixture of fatty acids and soybean oil to usable biofuels at 65 °C and 1 atm without leaching of the catalytic sites.”