Biodiesel from Corn Distillers Dried Grains with Solubles: Preparation, Evaluation, and Properties.

A coproduct of dry-grind ethanol fermentation, corn distillers' dried grains with solubles (DDGS) represents a low-cost feedstock with potential to integrate production of biodiesel and ethanol. Oil extracted from DDGS was converted into distillers' grains methyl (DGME) and ethyl (DGEE) esters. Pretreatment using sulfuric acid was effective at lowering the acid value of the crude oil from 27.15 to less than 0.30 mg KOH g, thus rendering it amenable to homogenous, base-catalyzed transesterification. Measurement of fuel properties and comparison to refined corn oil methyl (RCME) and ethyl (RCEE) esters revealed that the cold flow properties and oxidative stability of DGME and DGEE were deficient relative to RCME and RCEE. In the absence of antioxidants, DGME and DGEE did not meet the oxidative stability specifications of ASTM D6751 and EN 14214. The cetane number of DGEE was below the minimum limit specified in EN 14214. DGEE exhibited more favorable cold flow properties, iodine value, and energy content than DGME. Evaluation of blends (B5 and B20) in petroleum diesel fuel revealed that antioxidants and cetane enhancers would be required to meet the specifications of the US and European diesel fuel standards. Other fuel properties of the petrodiesel blends were largely neutral with respect to alkyl ester type and conformed to the limits specified in the respective standards. [ABSTRACT FROM AUTHOR]