Page 7 - Shimadzu Renewable Fuels Industry

Monitoring Biodiesel Production

Produced by transesterification, biodiesel is comprised of mono-alkyl esters of long chain fatty acids derived from vegetable
oils or animal fats. It thus differs differently from alkanes and aromatic hydrocarbons found in petroleum derived diesel. But
because it is miscible with traditional diesel in all proportions, biodiesel is compatible with all existing fuel infrastructures without
modifications.

Manufacture and Analysis
The choice of feedstocks for biodiesel manufacture depends on local availability and affordability. It can be produced from waste
vegetable oils, such as those used in cooking, but most commercial refiners currently consume unused oils. Refined soybean oil is
the most commonly used material in the United States and Brazil. The use of other feedstocks, such as rapeseed oil, kernel and
palm seed oils, and cottonseed oil, is rapidly increasing.
The transesterification reaction of triacylglycerols (TAGs) in oils is most commonly done by reacting TAGs with methanol in the
presence of a catalyst yielding the fatty acid methyl ester (FAME). During the process, monoacylglycerols (MAGs), diacylglycerols
(DAGs) and other intermediate glycerols are formed. These, along with unreacted TAGs, can remain in and contaminate the final
product, and potentially cause severe engine problems.

Free glycerin, along with water, is a byproduct of fatty acid methyl ester (FAME) production. GC analysis of glycerin concentration
yields an effective measure of fuel quality. Diesel fuel made from plants has the potential to contain glycerols in the form of free
glycerin, mono, di and tri glycerides. These compounds have been found to be detrimental to diesel engines so must be removed
prior to use.

ASTM method D6584 provides standard test method for the quantitative determination of free and total glycerin in B-100 methyl
esters by gas chromatography. Also, EN14105 specifies test method for determination of free and total glycerol and mono-, di-,
triglyceride contents by gas chromatography.

Biodiesel Standard Chromatogram: 1ul Chromatograms of Biodiesel-Blended Fuel (10 uL Injected)
injection of the Supelco Free, mono, di and
Triglycerides standard, level 4 concentration

Biodiesel Quality Control Features (GC)

• Conforms to ASTM method 6584 and DIN EN 14110
• Automated reporting of free and total glycerines in biodiesel fuel
• The injection technique uses Cool on column injection (OCI) to avoid discrimination effects.

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