Preliminary studies on the interesterification of soybean oil with methyl acetate catalyed by layered materials”

ABSTRACT

The partial replacement of diesel oil with biodiesel has contributed to the increased availability of glycerin on the world market. About 10 m³ of glycerol is obtained for every 100 m³ of triacylglycerides (main component of vegetable oils and animal fats) processed in the main technological route for biodiesel production, the alkaline transesterification in homogeneous medium. Of course, the glycerin obtained as a coproduct in the process needs to be harnessed in complementary processes. This is usually possible after the glycerin undergoes several purification processes. With the intention of avoiding such complementary processes, we are proposing the synthesis of biodiesel by interesterification of soybean oil with methyl acetate, a technological route that makes it possible to obtain glycerol in the form of triacetin, that is, already chemically modified. The catalysts used in the process were the layered double hydroxide (HDL) Zn₂ Al/NO₃ and the commercial zinc stearate (EZ), a layered carboxylate. Both these layered materials had not yet been tested as catalysts in interesterification reactions. Conversions were obtained in fatty acid methyl esters of 50.8 ± 4.2% and 82.9 ± 1.0% (m m^-1) using the EZ and HDL catalysts, respectively; when reactions were conducted using 5% catalyst (m m^-1), for 10 h reaction and molar ratio methyl acetate: soybean oil of 24:1.

Keywords
biodiesel; glycerin; triacetin; interesterification; layered materials