Temperature regulated Bronsted acidic ionic liquid-catalyze esterification of oleic acid for biodiesel application

By combining phosphotungstic acid (PW) and SO3H- functioned zwitterion, heteropoly anion-based Bronsted acidic ionic liquids (HPA-ILs) were successfully obtained. Scanning electron microscopy and energy dispersive X-ray spectroscopy were provided the morphology and composition of the prepared material. Catalytic performance and reusability of the catalysts were evaluated through an esterification reaction between oleic acid and methanol for production of biodiesel. Relationship between catalytic activities and acidity of the catalysts have been discussed by potentiometric titration. The results showed that HPA-ILs had good activity and reusability. HPA-ILs dissolved in the reaction mixture during the reaction process and could be precipitated and separated from products at lower temperature. (C) 2016 Elsevier B.V. All rights reserved.