Synthesis of methyl oleate catalyzed by 12-tungstophosphoric acid and its kinetics

The 12-tungstophosphoric acid(H_3PW_(12)O_(40),hereafter HPW) was employed as a homogeneous catalyst to promote the esterification of oleic acid with methanol.The effects of reaction conditions such as the methanol/oleic molar ratio,catalyst quantity,reaction temperature and reaction time on the synthesis of methyl oleate were investigated.The oleic acid conversion reached 91.1%under the conditions;methanol/oleic molar ratio of 12:1,HPW amount of 3.0%,reaction temperature of 341.15 K,and reaction time of 360 min.A kinetic model for the esterification was established.The experimental data fitted the pseudo second-order rate equation with a reaction order n=2.23.The apparent activation energy was calculated to be 48.79 kJ/mol.Compared with the traditional esterification,the process has some advantages: easy separation of the catalyst,reusabilty,lower energy consumption,reduced waste emission and so on.