In Malaysia, the raw material for biodiesel production has been palm oil. However, making biodiesel can conflict with the oil’s use as food, and growing palm oil (even for food) has caused the destruction of tropical forests in Borneo, Sumatra and other regions. A team from the Dept. of Chem. Eng. at the Universiti Teknologi Petronas, (Perak, Malaysia; edlinks.chemengonline.com/6902-544) has developed a process for obtaining biodiesel from rubber seeds, a non-edible feedstock.
Rubber-seed oil has a high content of free fatty acids (FFAs), which can lead to saponification in the presence of an alkaline catalyst. The university team has developed a combined process of oil extraction and transesterification, the latter of which occurs via in-situ, sequential acid and alkaline esterification. The first step extracts as much oil as possible using alcohols. Addition of an acid catalyst reduces the FFA to an acceptable level while simultaneously reacting with the extracted oil to form alkyl esters. The oil and some partially reacted oil are sent to the second step by adding alcohols and the alkaline catalyst. At this stage, the oils and intermediates are transesterified to alkyl esters. In the laboratory, a biodiesel yield of 83 wt.% has been achieved by this approach. The team is now improving the process using ultrasound and a heterogeneous catalyst.