Methylic and ethylic biodiesel production from crambe oil (Crambe abyssinica): New aspects for yield and oxidative stability

Abstract

Biodiesel is a fuel comprised of mono-alkyl esters of long-chain fatty acids derived from vegetable oils or animal fats. Biodiesel is designated B100 and is regarded as the major substitute for fossil diesel. Crambe abyssinica, a native plant from Ethiopia, has great potential for biodiesel production due to its higher calorific value and oxidative stability as compared to soybean oil biodiesel. Compared to fossil diesel, C. abyssinica oil biodiesel emits significantly less CO2 without efficiency loss. However, its crude oil only provides good results if it undergoes supercritical transesterification. Here, we aimed to produce ethyl and methyl esters from crambe oil under ambient conditions. Initially, we tested two methods to degum crambe oil: aqueous degumming and acid degumming. We subjected the degummed oil to transesterification through the methylic or the ethylic route, catalyzed by KOH. The methyl esters of the biodiesel obtained by esterification of crambe oil submitted to acid degumming had higher oxidative stability as compared to the methyl esters of the biodiesel obtained from crambe oil subjected to aqueous degumming: 15.7 h and 10.7 h, respectively, but the yield was lower: 70% vs. 80%, respectively. The ethyl esters of the biodiesel obtained from crambe oil submitted to aqueous degumming provided the highest yield and oxidative stability: 65% and 8.5 h, respectively. We also evaluated the oxidative stability of blends consisting of crambe oil methylic or ethylic biodiesel and soybean oil biodiesel.