The prediction of biodiesel storage stability. Proposal for a quick test

Abstract

Abstract The results obtained during the set‐up of a method for the prediction of biodiesel storage stability are shown. In order to speed up the rate of ageing processes, the test temperature was set to 80 °C, and tests were carried out within 24 h in a Rancimat modified cell apparatus. The effect of the quick ageing process can be monitored by means of the evaluation of changes in ester content, polymer content and peroxide value. By comparing the results obtained during a 1‐year experiment, carried out under real storage conditions, and during a second test, carried out at 43 °C for 24 wk according to ASTM D 4625 method, with the ones reported in this paper, several discrepancies regarding the different degradation reactions as well as the rate at which these reactions take place were evidenced. Finally, a tentative relationship between the results obtained with the proposed quick test and the real Rancimat induction period, shown by different samples after 12 months of real storage, are shown. From the results obtained during this work, the Oxidation Stability test carried out according to EN 14112:2003 and the Storage Stability test reported herein may provide different information for the evaluation of the overall stability of a biodiesel sample.