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Researchers in Brazil Use Ethanol and Lipases to Transesterify Palm Oil to Biodiesel with High Yield
7 October 2007
Researchers in Brazil have used lipases (enzymes that break down fats to glycerol and fatty acids) from several sources with ethanol to transesterify palm oil to biodiesel with high yield and quality meeting D6751 specifications. Their work, which appears in the journal Energy & Fuels, highlights the on-going interest in enzymatic processes for transesterification, rather than the commonly used alkali-catalyzed processes.
The common commercial process of transesterification of triglycerides to biodiesel using an alkali (NaOH, KOH, carbonates or alkoxides) offers high conversion levels and short reaction times. However, the process is relatively energy intensive, recovery of the byproduct glycerol can be difficult, the alkaline catalyst must be removed from the product, the wastewater requires treatment and free fatty acids and water can interfere with the reaction.
By contrast, enzymatic transesterification using lipases can overcome those issues. The reaction temperature is much lower, recovery of the glycerol is simpler and there is no spent catalyst to remove or wastewater to treat. Furthermore, the free fatty acids in the waste oils and fats can be completely convereted to alkyl esters. The enzymes can be recylcled for reuse or immobilized onto a substrate. One of the downsides, however, has been the production cost.
Other issues with enzymatic transesterification have been the speed of the reaction, yield and quality. The type of alcohol used also has an impact on the production yield. Earlier work has shown, for example, that ethanol is more effective than methanol in the conversion process.
The team from the University of São Paulo and the State University of Maringa experimented with lipases from from different sources (Thermomyces lanuginosus; Pseudomonas fluorescens; Burkholderia cepacia; Penicillium camembertii; and Candida antarctica, porcine pancreatic) immobilized on hybrid support polysiloxane–poly(vinyl alcohol) with ethanol.
Performance varied with the enzyme. The team obtained the best results from the lipase from Pseudomonas fluorescens, reaching almost full conversion (≅98 %) in less than 24 hours of reaction.
Purity of the fatty acid ethyl ester was high, having no glycerol bound. The other properties such as low water content (0.02%), specific gravity (0.8), and viscosity (4.97 cSt) were in accordance with the ASTM D6751 specifications.
This is an exceptional option for the Brazilian biodiesel production, because both palm oil and ethanol are readily available in the country.
—Moreira et. al.
Resources:
Ana B. R. Moreira, Victor H. Perez, Gisella M. Zanin, and Heizir F. de Castro. “Biodiesel Synthesis by Enzymatic Transesterification of Palm Oil with Ethanol Using Lipases from Several Sources Immobilized on Silica–PVA Composite” ASAP Energy Fuels, ASAP Article, 10.1021/ef700399b
Hideki Fukuda, Akihiko Kondo and Hideo Noda. “Biodiesel Fuel Production by Transesterification of Oils” Journal of Bioscience and Bioengineering, 92 (5), p.405-416, Jan 2001
Shweta Shah, Shweta Sharma and M N Gupta. “Enzymatic transesterification for biodiesel production” Indian Journal of Biochemistry & Biophysics Vol. 40, December 2003, pp. 392-399
Biodiesel Production Technology (NREL/SR-510-36244)
October 7, 2007 in Biodiesel | Permalink | Comments (9) | TrackBack (0)
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Comments
Very cool stuff. I was worried about the vast qty of lye used in the conventional commercial process. This appears much more benign.
Posted by: John Schreiber | Oct 7, 2007 3:36:51 PM
Ethanol is a safer alternative to methanol, as well. Methanol is much more toxic.
Posted by: Cervus | Oct 7, 2007 4:40:38 PM
In ethanol production, a lot of energy is needed for the distillation. This is not needed anymore when it is esterified with the fatty-acids. I wonder if the esters are hydrophobic. If so, no distillation must be done anymore, since the water and the esters separate by themselves.
Posted by: Alain | Oct 7, 2007 5:03:30 PM
No the ester retain some water, but evaporating that water is easier then distilling ethanol, beside the lipase need some water to function, thankfully the glycerol takes most of the water with it.
Posted by: Ben | Oct 7, 2007 8:11:00 PM
What has happened to the microchannel reactor developed at Oregon university? http://cbee.oregonstate.edu/research/jovanovic/
It apparently needs alcohol but no alkali or enzymes. The current form of biodiesel is clearly not a long term solution as lyes and cheap methanol will decline with fossil fuels.
Posted by: Aussie | Oct 8, 2007 5:24:42 AM
It would be interesting to combine this with the proposed method of fermenting the glycerol byproduct into ethanol, from a Dr. Ramon Gonzalez at at Rice University.
Aussie- weren't lye and methanol originally produced from wood? The supply of lye could get tighter, but I would have guessed that methanol supply would rise as oil diminishes as it's one of the lower tech alternatives to gasoline.
Posted by: | Oct 8, 2007 6:40:25 AM
The supply of lye could get tighter,
Lye (sodium hydroxide) is produced industrially from electrolysis of brine. No fossil fuels are required for its production.
Posted by: Paul Dietz | Oct 8, 2007 10:41:14 AM
I had always thought of lye as potash (potassium hydroxide); sure enough, Wikipedia says either NaOH or KOH can be used. But then that just reaffirms that none of these things require fossil-fuel input, as KOH can be gotten from wood ash.
Posted by: Jim G. | Oct 8, 2007 1:07:59 PM
9aef04fcabd1ddf59b0d6577d7b8cd8d
Posted by: John Doe | Mar 20, 2008 12:34:26 AM
