Using ionic liquid catalyst for conversion of waste polyethylene terephthalate and soybean oil to polyester polyol

ABSTRACT An imidazolium ionic liquid was synthesized, characterized and used as a catalyst for conversion of polyethylene terephthalate (PET) and soybean oil to polyester polyol (PE polyol). The degradation of PET waste was carried out using glycerol and low cost soybean oil that resulted in the formation of PE polyols. Formed PE polyols were characterized using Fourier transform infrared (FT‐IR) and mass spectra method, thermo gravimetric and differential thermal analysis and gel permeation chromatoghraphy. The first step in the overall process is proposed to be the transesterification of soybean oil with glycerol to form monoglyceride or/and diglyceride of soybean oil fatty acids. In the second step, the obtained glycerides can react with PET to form PE polyol. Both steps could be combined in one process and acidic catalyzed by an ionic liquid. Ionic liquid can be used as active catalyst and show a high reusability. The influence of some factors such as amount of glycerol used in transesterification of soybean oil with glycerol, PET degradation time, and temperature on PET conversion were investigated to find the suitable conditions for the process. Under suggested optimum parameters (mass ratio of soybean oil to glycerol of 2:1, a time of 8 h and a temperature of 180 °C for PET degradation), a PET conversion of 87.3% was reached. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 43920.