Esterification Of Oleic Acid For Biodiesel Production Catalytic Over Novol Solid Acid Based Heteropoly Acid

With the increasing tension of traditional fuels and the increasingly prominent environmental problems,biodiesel has been used as a substitute for fossil fuels because of its similarity to diesel and the environmental protection of combustion products.Biodiesel can be obtained through esterification or transesterification of oil(animal,plant,microbial)or waste oil with short alcohol.The esterification of free fatty acids(including oleic acid,linoleic acid,HPAlmitic acid,stearic acid,etal)and methanol is an effective method for the synthesis of biodiesel.The catalyst currently used in esterification is some inorganic acid,such as sulfuric acid and phosphoric acid.These will produced a large number of waste acid and can not be reused easily in this reaction.And their use will corrosion equipment and bring serious environmental pollution problems.Compared with liquid acid,solid acid catalyst has many advantages,such as easy separation,low corrosion and reusable.Heteropoly acid containing special structure is widely applied in the catalytic reaction because of its strong acidity,redox properties and so on,especially those that has been modified.And modified heteropoly acid has been applied in esterification reaction.In this paper,heterocyclic compounds containing nitrogen were used to modify heteropoly acid or single inorgatic oxysalt and obtain a series of organic-inorganic hybrid compounds(organic-phosphotungstic acid,organic-phosphomolybdic acid,organic-molybdate).These modified catalyst were analyzed by X ray powder diffraction(XRD),electron microscope(SEM),infrared spectroscopy(FT-IR),thermogravimetry(TG)and the potentiometric titration.Then esterification of oleic acid with methanol was used to studied the performance of modified catalysts as the probe reaction.Some influence factors on esterification reaction such as catalyst dosage,reaction time,reaction temperature,molar ratio of methanol/oleic acid and catalyst reuse were systematically and the optimal reaction conditions for each catalyst was obtained through this reaction.