Soybean oil ethanolysis over Ca based catalyst. Statistical optimization of reaction conditions

Abstract

Ethanolysis of soybean oil was carried out over lime catalyst produced by calcination of scallop shells food wastes. The as prepared catalyst showed XRD lines belonging to lime, whereas post reaction samples presented XRD pattern belonging to Ca(OH)2 overlaid with lines of calcium diglyceroxide. The catalyst dynamics during ethanolysis was similar to that reported for methanolysis, being hydration and consequent diglyceroxide formation the main transformations of CaO catalyst during reaction. The influence of the reaction parameters, such as ethanol:oil molar ratio (10:1–14:1), catalyst loading (10–15%, based in oil weight) and time reaction (6–10 h), on the FAAE (fatty acids ethyl esters) yield was analyzed by response surface methodology. A polynomial model was fitted using Minitab software, showing a correlation between predicted and experimental FAEE yields of 0.921. The maximum FAEE yield of 99.2% was computed for optimal reaction parameters of 11:1 ethanol:oil molar ratio; 13.8% catalyst loading and 9.1 h of reaction time. The fitted model was verified for the optimal conditions, using three replicas, given 99.0% of FAEE yield instead of the 99.2% predicted.