H 3 PW 12 O 40 incorporated in/on polyacrylamide, a new catalytic system for the oleic acid esterification

(20–50%.wt) H 3 PW 12 O 40 incorporated in/on polyacrylamide (HPW/PAA) was prepared by three methods (M1-3). HPW was introduced by simple diffusion into the PAA (M1), by adding together with the reagents of the PAA synthesis (M2) and by addition dropwise during the PAA synthesis (M3). The resulting systems were characterized by FTIR spectroscopy, XR Diffraction and SEM analysis and tested in the oleic acid esterification at 60 °C in the presence of methanol (methanol/oleic acid molar ratio: 29/1). The swelling capacity of the HPW/PAA systems was studied in aqueous and methanolic mediums and in a methanol/oleic acid (29/1) mixture at 25 and at 60 °C. Methyl oleate, esterification product, was analysed and quantified by gas chromatography. Regardless of the method used, 20%.wt HPW/PAA system showed the highest yield of methyl oleate, with 93, 95 and 43% for M1, M2 and M3, respectively.