The effect of the acidity of rapeseed oil on its transesterification.
The aim of this work is to study the transesterification of vegetable oil with a high acid number at unchanged reaction conditions. Rapeseed oil was used as the raw material and its acid number was changed by the addition of oleic acid (from 0.89 to 12.25 mg KOH/g). Methanol was used for transesterification (molar ratio of oil to methanol 1:6) and potassium hydroxide was used as a catalyst. After the reaction time, the residue of the catalyst was neutralised by gaseous carbon dioxide and the methanol excess was removed. After the separation of two phases, each of them was analyzed (in the ester phase: yield, content of methyl ester and acid number; in the glycerol phase: yield, density, viscosity, content of glycerol, soaps, methyl ester, potassium carbonate and hydrogen carbonate). The obtained data was compared with theoretical material balances and the effect on the saponification of oil was discussed. The results show that the yield of methyl ester (biodiesel) is significantly affected by a higher acid number, as well as enhanced soap formation. On the other hand, the conversion of the oil and acid number of the ester phase remain at constant values in studied borders.
Kwiecien
Jirí
J
Department of Physical Chemistry, Faculty of Chemical Technology, University of Pardubice, Pardubice, Czech Republic. jiri.kwiecien@post.cz
Hájek
Martin
M
Skopal
Frantisek
F
D001639:Bicarbonates / Q000737:chemistry; D001709:Biotechnology / Q000379:methods*; D002245:Carbon Dioxide / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry; D002384:Catalysis; D004736:Energy-Generating Resources; D004951:Esterification; D004952:Esters / Q000737:chemistry*; D005227:Fatty Acids / Q000737:chemistry; D005229:Fatty Acids, Monounsaturated; D005990:Glycerol / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry; D000432:Methanol / Q000737:chemistry; D009829:Oleic Acids / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry; D000074262:Rapeseed Oil
D001639:Bicarbonates; D002254:Carbonates; D004952:Esters; D005227:Fatty Acids; D005229:Fatty Acids, Monounsaturated; D006878:Hydroxides; D009829:Oleic Acids; D010938:Plant Oils; D017680:Potassium Compounds; D000074262:Rapeseed Oil; D002245:Carbon Dioxide; C037593:potassium carbonate; D005990:Glycerol; D011188:Potassium; C029943:potassium hydroxide; D000432:Methanol