Synthesis of Cross-Linked Poly Acidic Ionic Liquids and its Application in Biodiesel Production

Brӧnsted acidic poly ionic liquid (PIL-M) was successfully prepared by free-radical polymerization. The surface area of the heterogeneous catalyst was 301.1 m2/g. The result of thermogravimetric (TG) proved that PIL-M had good thermal stability (decompose at 410 °C). The optimal reaction condition was as follows: 6 wt% catalyst amount, reaction temperature 80 °C, the ratio of methanol to oleic acid 9:1 and reaction time 3 h. Under the optimal condition, the yield of methyl oleate was up to 95.9%. The excellent catalytic activity of PIL-M in the product of biodiesel benefit from its excellent properties such as high surface area (301.1 m2/g) and hierarchical nanopores. Compared with commercial resin (Amberlyst 15) and other catalysts, PIL-M showed better catalytic activity. The yield of methyl oleate was still over 90% after four times reuse. The structure of PIL-M kept stable after four times reuse, which was confirmed by the FT-IR spectrum.