| Molybdovanadophosphoric heteropoly acid (H4PMo11VO40) catalyst was synthesized using Na2MoO4·2H2O, Na2HPO4·12H2O and NaVO3 as raw materials. The chemical structure and thermal stability of H4PMo11VO40were characterized by UV-Vis, FTIR and TG-DTG and it was used as catalyst in the esterification of oleic acid and methanol. The results showed that the characteristic absorption peaks of P—O bond, Mo—O bond and Mo—O—Mo bridge bond could be observed obviously in FTIR spectra of H4PMo11VO40; H4PMo11VO40 had a clear ultraviolet absorption peak at 308 nm; it was provided with high thermal stability above 209℃. When the molar ratio of oleic acid to methanol was 1∶6, the dosage of catalyst was 9% (based on the mass of oleic acid) and the reaction time was 7 h, the esterification rate of oleic acid reached 90.7%. After the catalyst was reused for five times, the esterification rate of oleic acid was still above 85%. Therefore, heteropoly acid H4PMo11VO40 could be repeatedly used and easily separated from the product. |
