Synthesis of Biodiesel from Soybean Oil Using Lewis Acidic Ionic Liquids Containing Metal Chloride Salts

Production of biodiesel from soybean oil catalyzed by Lewis acidic ionic liquids(ILs) containing metal chloride salts was investigated in this study. Metal chloride salts, such as SnCl 2, ZnCl2, AlCl3, FeCl3 and CuCl, were screened for oil transesterification in the range of 363-423 K. Among these metal chlorides, tin chloride showed particularly high catalytic property for the oil transesterification. Similarly, among these Lewis acidic ionic liquid catalysts, [Me-3 NC2H4OH] Cl-2SnCl(2) resulted in a high fatty acid methyl esters(FAMEs) content of 91.1% under the following reaction conditions: 403 K, 14 h, and a molar ratio of 1: 12: 0.9 (oil: methanol: catalyst). Unlike the pure tin chloride catalysts, Lewis acidic ILs containing tin chloride [Me-3 NC2H4OH] Cl-2SnCl(2) catalyst could be recycled up to five times without any significant loss of activity by separating from the FAMEs with simple decantation. The Lewis acidity and high moisture-stability of this catalyst appeared to be responsible for the excellent catalytic performance. The effects of reaction time and the molar ratio of methanol/catalyst to oil on the FAMEs production were also studied in this work.