Fatty acid ethyl esters advantages

The fatty acid methyl/ethyl esters of vegetable oils such as jatropha, Mesua ferrea, soybean, rapeseed, cottonseed, sunflower, safflower, peanut and linseed can be used as an alternative fuel for diesel engines (biodiesel) Methyl and ethyl esters of vegetable oils have several outstanding advantages among other new renewable and clean engine fuel alternatives. The... 

It is clear that moulds represent excellent sources of dietetically acceptable oils. The main difficulty is one of sales and marketing as it obviously is not easy to convince a suspicious public that mould oil is as good as a plant oil. Scientifically, there is no detriment to using mould oil. Indeed one positive advantage of the mould oil as a source of GLA is its much lower content of linoleic acid (18 2) than either of the plant sources. This makes the purification of GLA much easier than starting from the plant oils as the main problem is the separation of the two closely allied fatty acids. Simple urea adduct formation enables oils with 80-85% GLA to be produced. Solvent winterization has also been used but without great effect (Yokochi et al., 1990) although the best, but most expensive, procedure for purification is by use of zeolites where 98% pure GLA has been obtained as its ethyl ester (Arai et al., 1987). Enrichment... 

Efficient enzymatic conversion can be achieved even though most of the reactants are present as solids, provided that there is a liquid phase in which the reaction can occur. This approach has been successfully used for carbohydrate ester synthesis with synthesis of glucose esters of fatty acids between C12 and C18 as typical examples [34]. It is important that the substrates dissolve during the reaction, and often the products precipitate as they are formed, which can be an advantage due to a favourable effect on the equilibrium position. Candida antarctica lipase B is an efficient catalyst in this system and solvents used (in moderate amounts) include ethyl methyl ketone, acetone or dioxane. In order to increase the ester yield, water formed in the reaction can be removed by azeotropic distillation and the solvent (e.g. ethyl metyl ketone) can after condensation be dried by pervaporation, giving a practically useful complete process [35]. 

Further improvement in the technology of methyl fatty ester synthesis can be achieved by dual esterification [4], This takes advantage of the fact that the sulfated zirconia catalyst has similar activity for normal alcohols, over the series C1-C8. However, methanol manifests about twice the activity [20], The removal of water produced by the esterification with methanol is solved simply, by employing a heavy alcohol immiscible with water, such as 2-ethyl-hexanol, which acts simultaneously as a reactant and an entrainer. As a result, the two fatty esters are obtained in the bottom product in the desired ratio by adjusting the feeds. For example, in a preferable operation mode the ratio of fresh feed reactants is acid methanol 2-ethyl-hexanol 1 0.8 0.2. 

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