Synopsis by Wim Thielemans, Dec 20, 2011
Scientists in Singapore develop a new chemical catalyst with fewer drawbacks than current versions to help make biodiesel production more attractive and sustainable.
A modified version of a well-known but inefficient chemical catalyst can propel faster, cleaner reactions that turn plants into diesel fuel better than existing methods.The new calcium-based catalyst is more reactive, stable and easier to recover from the final product, the Singapore researchers report in the journal Green Chemistry. While the catalyst may solve a major stumbling block in the effort to produce biodiesel, the process will need more testing in industrial settings.
Biodiesel production is gaining in importance as petroleum supplies become more limited and concern about climate change grows. Biodiesel can be used in unmodified diesel engines. Its use results in near-zero carbon dioxide emissions, if estimates consider plant growth, which extracts carbon dioxide from the atmosphere.
Biodiesel is generally produced from plant oils. Plant oils are star-like molecules with three arms. To turn the plant oil into biodiesel, the three arms need to be removed from the center. The separated arms then form the biodiesel.
Unfortunately, this transformation does not happen readily without chemical help. Chemists must use other molecules, called catalysts, to speed up this reaction.
Current catalysts make the reaction go faster, but they have various drawbacks that hamper their use on the large scale of a commercial biodiesel process. These drawbacks include: large amounts of catalyst may be needed; high temperatures are necessary to propel the reactions; the catalyst may be less stable if it is used for a longer time; it can be difficult to remove the catalyst from the final product; and the solid catalysts may be slow to dissolve into the biodiesel product.
Calcium-based catalysts – which are cheap and abundant – can break up the star-like plant oils. Unfortunately, they dissolve into the biodiesel and removing them generates large amounts of wastewater.
To solve this problem, researchers from Singapore made a new and very reactive calcium-based catalyst with high stability. The catalyst was formed from a solution containing calcium and cerium – a metal found in a number of minerals. By making the solution less acidic, the catalyst precipitates out and is recovered by filtering and drying.
The ratio of calcium and cerium was varied to see which combination would give the best catalyst performance. Cerium alone does not work very well.
The best catalyst found could be reused up to 18 times with more than 90 percent of plant oils separated into their arms. Very low amounts of the catalyst dissolved into the biodiesel.
This work is certainly promising as it may make biodiesel production more sustainable and cheaper. Of course, the catalyst will need to be tested in an industrial process. Read more science at Environmental Health News.
This figure is taken from Green chemistry: state of the art through an analysis of the literature by V. Dichiarante, D. Ravelli and A. Albini. Green Chemistry Letter and Reviews Vol. 3, No. 2, June 2010, 105-113.
Green Chemistry at Virginia Tech Part II
Wednesday, January 4th, 2012In his own labs on campus, Dr. Turner has a few projects in melt phase rather than in solution as described above. His lab is also trying to make polymers that capture carbon dioxide. He describes:
“Carbon dioxide build-up in the atmosphere is going to be an increasingly large issue – we have to invest in the research now to learn how to capture and sequester the carbon dioxide. Polymer particles have huge surface areas, with ligands that can capture CO2. The sorbent (“a material used to absorb liquids or gases,” according to Wikipedia; yes, I had to look it up) and ligands capture CO2 and then moves it to reactor where it releases it, concentrating the CO2.”
Dr. Turner is also on the science advisory board of the company, Novomer, which was featured in a previous article on converting oranges to plastic. He works on biodegradability and reducing the overall energy footprint. “We have to make sure we do really tough and detailed analysis of our choices.”
In the classroom, Dr. Turner teaches a course called: “Future Industrial Professionals in Science and Engineering”. The course caters to scientists and engineers who want to go into industry. He divides the class into groups who run individual projects; this year all the projects were sustainability driven. There were three projects in total: the first worked to extend the shelf life of food; the second worked to improve battery life; the third worked to make a better membrane for reverse osmosis.
Outside of his own class, Dr. Turner was impressed with Tech’s sustainability. He discussed the accomplishments of the College of Natural Resources and the Environment, while also noting the strong Renewable Resources Group.
AGC applauds Dr. Turner’s hard work with sustainable chemistry, and hopes it serves as inspiration to other chemists.
Tags: CO2, education, GREEN CHEMISTRY, greener process
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