Sulfonic acid group functionalized Brönsted acidic ionic liquid catalyzed depolymerization of poly(ethylene terephthalate) in water

Sulfonic acid group functionalized 1,3-dialkyl imidazolium Brönsted acidic ionic liquids are shown as better catalysts in comparison to sulfuric acid with similar acid concentration for the depolymerization of poly(ethylene terephthalate) in hot compressed water. The highest activity was found by using 1.00 M aqueous 1-(3-propylsulfonic)-3-methylimidazolium chloride catalyst, where a practically complete decomposition of poly(ethylene terephthalate) could be achieved after 24 h at 210 °C with a 94% isolated yield of terephthalic acid. The superior catalytic activity of 1-(alkylsulfonic)-3-methylimidazolium chloride in comparison to sulfuric acid with similar acidic strength is explained as a result of charge-transfer and dipolar interactions between catalyst and poly(ethylene terephthalate).