Page 131 - Biofuels Refining and Performance

114 Chapter Four

Köse et al. investigated the transesterification of refined cottonseed
oil, using primary and secondary alcohols (oil–alcohol molar ratio 1:4)
in the presence of an immobilized enzyme from Candida antarctica (30%
enzyme, based on oil weight). The reaction was carried out at 50 C for 7
h, showing that conversion using secondary alcohols was more effective
[65]. Some authors have also proposed the use of lipase with methanol
[66]. Royon et al. used the same catalyst in a t-butanol solvent. Maximum
yield was observed after 24 h at 50 C with a reaction mixture contain-
ing 32.5% t-butanol, 13.5% methanol, 54% oil, and 0.017 g of enzyme per
g of oil [67]. Recent tendencies propose the use of ultrasonically assisted
extraction transesterification to increase ester yield [68].

4.2.4 Cuphea oil
Crop description. Cuphea spp., C. carthagenensis, C. painter, C. ignea,
and C. viscosissima—commonly known as cuphea—belong to the family
Lythraceae and grow in temperate and subtropical climates (see Fig. 4.5).
They can be found in Central and South America, and have been grown
in trials in Germany and the United States. The seeds of Cuphea con-
tain about 30–36% oil [69]. Major fatty acid composition of the oil
includes caprylic acid (73% in C. painter, 3% in C. ignea), capric acid
(18% in C. carthagenensis, 24% in C. painteri, 87% in C. ignea, and
83–86% in C. llavea), and lauric acid (57% in C. carthagenensis) [70].

Main uses. It contains high levels of short-chain fatty acids, very inter-
esting for industrial applications. Previous studies have suggested that
oil composition and chemical properties of C. viscosissima VS-320 are
not appropriate for use as a substitute for diesel fuel without chemical

Figure 4.5 Cuphea sp. (Photo courtesy of Dr. Alvin R. Diamond
[http://spectrum.troy.edu/~diamond/PIKEFLORA.htm].)