Supercritical fluid technology in biodiesel production: pilot plant design and operation

The profitability of biodiesel is nowadays limited by the price of raw materials, which require high purity standards to be employed in conventional production processes. To overcome this problem, the transesterification of triglycerides in alcohol supercritical conditions could be conveniently used: the non-catalytic nature of this process allows the use of recycled raw materials, which are cheaper. To this end, a pilot scale plant for the continuous production of biodiesel in supercritical conditions was designed, manufactured and operated. In this research paper, rapeseed oil and bioethanol were used as raw materials, and the investigated temperatures were between 200 and 340 degrees C, the pressure between 150 and 240 bar, and the alcohol-to-oil ratio ranged between 9 and 100. The best fatty acid ethyl ester (FAEE) yields were obtained at 340 degrees C, 240 bar and a molar ratio of 42, which is line with easier-to-control lab-scale tests in batch conditions found in the literature. This encourages widening of the operating conditions to further improve the maximum achievable yields for the rapeseed oil-ethanol system.