According to the National Renewable Energy Laboratory, a branch of the Department of Energy, biodiesel “represents a significant energy resource and could someday supply 3 percent to 5 percent of the distillate fuel market.”  That assertion requires a lot more technology for getting from raw materials to fuel products.

Brown University assistant professor of chemistry Jason Sello and postdoctoral researcher Aaron Socha report in Organic & Biomolecular Chemistry that they were able to convert waste vegetable oil to biodiesel in a single reaction vessel using environmentally friendly catalysts. Their process is also six times faster than current methods for converting waste vegetable oil to biodiesel, so it consumes less energy.  This is called breakthrough.

The major obstacle to achieving a big bio diesel increase is figuring how to efficiently convert the abundant stocks of waste vegetable oil into biodiesel fuel. The current techniques take time, are costly and are inefficient. Even more difficult, the conversion requires the toxic chemicals sulfuric acid and either potassium hydroxide or sodium hydroxide, which must be contained and recycled.

Socha & Sello at Brown U. Click image for the largest view.

Sello said, “We wanted to develop an environmentally benign and technically simple way to convert waste vegetable oil into biodiesel. The production of energy at the expense of the environment is untenable and should be avoided at all costs.”  There’s the politically correct opening.

The problem is waste vegetable oil is made up of triacylglycerols, free fatty acids, and water. The conventional way to convert waste vegetable oil into biodiesel requires two separate reactions. The first reaction turns the free fatty acids into biodiesel, but that conversion requires sulfuric acid. The second reaction converts the triacylglycerols into biodiesel, but that conversion requires sodium hydroxide or potassium hydroxide. Sodium hydroxide/potassium hydroxide and sulfuric acid are not compatible with each other, so the reactions must be carried out in separate vessels. That makes the process less efficient and complex.

To find a better way, Sello and Socha went looking for catalysts that would be cheap, chemically stable and of limited toxicity. They settled on the metals bismuth triflate and scandium triflate, commonly used as catalysts in preparative organic chemistry. In addition, they performed the reactions using a microwave reactor instead of a conventional thermal heater. What they found was the new catalysts converted waste vegetable oil into biodiesel in about 20 minutes in the microwave reactor, whereas current reactions without catalysts using a conventional heater take two hours. While their microwave method needs a higher temperature to pull off the biodiesel conversion — 150 degrees Celsius versus 60 degrees Celsius under current methods — it uses less energy overall because the reaction time is much shorter.

The chemists also were able to perform the conversion in one reaction vessel, since the catalysts can promote both the reaction that converts free fatty acids into biodiesel and the reaction in which triacylgycerols are converted to biodiesel.

The team also reports that the catalysts in the free fatty acid conversion, which is the more challenging of the two reactions, could be recycled up to five times, while maintaining the capacity to promote a 97 percent reaction yield. The fact the catalysts can be recycled lowers their cost and environmental impact, the researchers report.
Sello continues, “While we have not yet proven the viability of our approach on an industrial scale, we have identified very promising catalysts and reaction conditions that could, in principle, be used for large-scale conversion of waste vegetable oil into biodiesel in an environmentally sensitive manner.”

Meanwhile  . . . a team led by Brown chemistry professor Paul Williard has created a new technique to chart the progress of a reaction in which virgin oils are converted into biodiesel fuel has been published in the Journal Energy and Fuels. It seems Brown U’s people are hot on knocking off 5% of the diesel market for the bio diesel producers.

The technique, called DOSY (for diffusion-ordered nuclear magnetic resonance spectroscopy), observes virgin oil molecules as they shrink in size and move faster in solution during the reaction. The reaction is complete when all of the molecules have been converted into smaller components known as fatty acid esters. These fatty acid esters are used as biodiesel fuel.  Just the thing for monitoring.

These two efforts show that innovation with natural substances can help close up the gap with fossil fuel imports.  All the politically correctness aside, there is an ocean of oil produced each year a large part of which isn’t consumed that can be recycled back into fuels products.  It’s a little hard to imagine, but one day that used cooking oil is going to be worth enough to not go down the drain.  Together the 5% number is a bit low and dedicated production and better crop varieties could move the number up greatly.

From the harrowing experience over the past couple of years, bio diesel producers need a little good news. Cutting those costs with a better process will be welcome, both at the producer and consumer points of view.


9 Comments so far

  1. Biodiesel Might Make a Worthwhile Contribution | New Energy and Fuel | on October 12, 2010 3:22 AM

    […] the original here: Biodiesel Might Make a Worthwhile Contribution | New Energy and Fuel This entry was posted in Industrial Scales and tagged approach, catalysts-and, have-identified, […]

  2. Matt Musson on October 12, 2010 8:48 AM

    3% does not seem like a lot. But, base hits are needed. They are a lot easier to come by then grand slams.

  3. JimW on October 20, 2010 8:53 AM

    but it still spews carbon!! I am told the only non carbon working sustainable replacement for oil is Why are we not putting more effort into one that is working rather than one that might work?

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