Predicting the Oxidation Stability of Soybean Oil/Coconut Oil Biodiesel Blends as a Function of Feedstock Mass Fraction

Biodiesel is a cleaner burning, renewable fuel that has noted benefits both in its neat form as well as in blends with diesel, where it adds useful lubricity and other properties. However, a drawback of biodiesel is that after a period of months, significant amounts of peroxides are formed, which cause polymerization in the fuel and may lead to engine damage. Predicting at what point polymerization will occur in storage is performed using accelerated shelf life, or oxidation stability tests.

In this study Equations for oxidation stability, based on feed stock mass fraction, of biodiesel blends were developed. The feedstocks were combined prior to the transesterification reaction. The oxidation stability of blended coconut oil and soybean oil feedstocks was examined using Rancimat and PetroOxy testing methods. The oxidation stability of the biodiesel blend can be accurately predicted using a third order equation, solely as a function of coconut oil or soybean oil mass fraction.