Biodiesel: The study of methyl esters loss in the glycerol phase at various conditions

The methyl esters loss in the glycerol phase was studied for three methods of transesterification stopping by neutralisation of catalyst by (i) carbon dioxide gas, (ii) carbon dioxide gas with addition of water to accelerate the separation and (iii) exact amount of phosphoric acid. It was found that the addition of water caused increase of the esters loss. The distribution of methyl esters depending on higher fatty acids in the glycerol phase was also studied. The distribution was different for each method of stopping and also different from distribution in the input oil. In the case of stop by phosphoric acid, the methyl esters loss was studied in detail, because the formed methyl esters conform to EN 14214 without any purification of the ester phase. The statistical analysis of relationship between methyl ester loss and the independent variables (molar ratio of methanol to oil, catalyst amount, reaction temperature and time) including the distribution was carried out. The esters loss increase with increasing catalyst amount and reaction temperature, while the relationship between molar ratio and methanol to oil is ambiguous. (C) 2018 Elsevier Ltd. All rights reserved.