Non-Polluting Esters

Sumitomo Chemical has developed a new process to produce fatty acid methyl esters without generating any environmentally undesired by-product, by the reaction of methanol with vegetable oil in a supercritical state. Fatty acid methyl esters are widely used as intermediates for higher alcohols which are raw material for surfactants.

Conventionally, fatty acid methyl esters have been manufactured by reacting methanol with vegetable oil, such as rapeseed oil and soybean oil, in the presence of alkaline catalysts like sodium hydroxide. However, the use of alkaline catalysts necessarily involves the formation of a by-product soap component, which needs to be removed by means of water rinsing at the end of the production process. This post-treatment step requires increased investment in environmental measures, resulting in higher production costs.

With Sumitomo's new method, however, methanol is reacted at supercritical temperatures (above 240°C) at which the reaction rate can be increased substantially, producing fatty acid methyl esters with a high yield without the use of any catalyst. What is more, the reaction can also be accelerated when conducted above the critical pressure of 8 MPa so that the reactor can be made compact in design. Moreover, the process has another advantage of being able to co-produce glycerin which can be highly purified by a simple phase separation.