Postingan
Commercially, methyl esters of fatty acids can be produced either by esterification of fatty acids or transesterification of fatty triglycerides. The predominant process for production of methyl esters is transesterification of fats and oils with methanol. The ester interchange, i.e. replacement of the glycerol component by methanol, takes place quite easily at low temperature, 50°C to 70°C, and under atmospheric pressure with excess methanol and an alkaline catalyst such as sodium hydroxide (Sonntag, 1982; Kreutzer, 1984 and Freedman et al., 1984). These mild reaction conditions, however, require oils neutralized by alkaline refining, steam distillation or preesterification of the free fatty acids.
Esterification may be carried out batchwise at 200°C to 250°C under pressure. For high yield, the water produced during the reaction has to be removed continuously. Esterification can also be carried out continuously in a countercurrent reaction column using superheated methanol (Kreutzer, 1984). Esterification is the preferred method for ester preparation from specific oil and fat fractions such as palm stearin and olein. Vegetable oils such as CPO with varying amounts of free fatty acids can be converted to esters in a continuous process by combining the esterification and transesterification processes. This esterification process is obviated, an economic advantage. The patented process can also be applied to other raw materials such as crude palm stearin, crude palm olein, crude palm kernel oil and palm kernel products.
Alternatively, the process can also be applied to produce methyl esters of neutralized palm oil, refined, bleached and deodorized (RBD) palm oil and RBD palm olein. In this respect, only transesterification section is sufficient to convert these raw materials into their respective methyl esters.
