Codoped Phosphotungstate as an Efficient Heterogeneous Catalyst for the Synthesis of -Butyl Oleate.

A quaternary ammonium and titanium codoped phosphotungstate (QATiHPW) catalyst was prepared by the ion exchange method and used as a solid acid catalyst for the synthesis of -butyl oleate. The catalyst was characterized by Fourier transform infrared, elemental analyzer, energy-dispersive X-ray spectrometry, Brunauer-Emmett-Teller, scanning electron microscopy, and Hammett indicator methods. QATiHPW showed a higher catalytic activity than other phosphotungstate solid acid catalysts reported by literature, and the esterification rate reached 99% under optimized conditions. Moreover, QATiHPW exhibited well reusability. An esterification rate of 90.1% was still obtained in the eighth run.