Sugar and vegetable oil are all you need to make biodiesel, say researchers in Japan.

Sugar and vegetable oil are all you need to make biodiesel, say researchers in Japan.

Masakazu Toda and colleagues at Tokyo Institute of Technology have made a solid recyclable catalyst from glucose and sucrose in an attempt to clean up the biodiesel production process. They produced a carbon catalyst that accelerates the esterification process that turns two constituents of vegetable oil - oleic acid and stearic acid - into biodiesel.

But more work needs to be done before Toda’s claims for a sugar-based acid catalyst can be verified, said green chemistry expert Keith Smith at the centre for clean chemistry, University of Wales Swansea, UK. 

’I’m not surprised that it works,’ said Smith, ’but it has not been tested directly on the fats and oils used in the biodiesel process.’ 

Biodiesel is made by esterifying the fatty acids in raw vegetable oil with an acid catalyst, but this produces a problematic byproduct, glycerol. Toda’s group has avoided the glycerol problem, but made their tests unrealistic by testing their acid catalyst on refined oil products rather than the raw material, said Smith.

Toda’s catalyst is easy to recycle, adding to its ’green’ credentials. But while it is always useful to have a recyclable catalyst, said Smith, the biggest environmental benefit of biodiesel is not the catalyst, but the renewable vegetable oil. 

’The catalyst needs to be effective but it doesn’t need to be made from sugar,’ said Smith. He would like to see Toda’s catalyst compared with more acid catalysts, like aluminosilicates made from sand. Katharine Sanderson