Ionic Liquids To The Study Of Fatty Acid Esterification

Biodiesel as an alternative to petroleum-based fuels has the potential of green renewable energy,and give us the hope of solving the energy crisis. However, raw materials as the bottleneck of the development of biodiesel, always restrict the development of biodiesel in our country, due to the constraints of the actual situation in our country,to produce biodiesel with edible oil such as soybean oil and rapeseed oil, as the raw materials lacks the practical significance, therefore, the use of low-cost trench oil as raw materials to produce bio-diesel is of more economic value and practical significance.Waste oils are a kind of oil which have a high degree of rancidity and their fatty acid content are high, so using alkaline catalyst to produce biodiesel directly will occur saponification reaction, and consume large amounts of alkaline catalyst, thereby increase the costs greatly. The fatty acids must be removed from the raw material first by pre-esterification. The traditional catalytic for esterification mainly use sulfuric acid and other acids, these catalysts are strong corrosive to the equipment, and the catalyst can not be reused, and need high costs of wastewater treatment, its discharging will cause the environment pollution. Ionic liquids are a new type of reusable green solvents, and have many benefits such as high reactivity, very low vapor pressure, thermal stability. Ionic liquids are a new type of reusable green solvents, and have many high benefits such as high reactivity, very low vapor pressure, thermal stability.The current study for the ionic liquids mostly use imidazolium-based ionic liquids,in this paper four kinds of water-stability acidic ionic liquids with pyridine, triethylene amine were prepared and characterized by infrared spectrum (IR), and thermogravimetry(TG). Under the esterification conditions:n(ethanol):n(oleic acid)=6:1, temperature 77℃and time 6h, mass percentage of catalyst relative to oleic acid 8%, the ionic liquid 1-ethyl-pyridinium hydrosulfate showed the best catalytic activity and the yield of ethyl oleate could reach 95.9%.In esterification of fatty acid to fatty acid methyl ester, the four ionic liquids showed good activities, and the yield of fatty acid methyl ester were all above 94%.After that,use the four good activity ionic liquids for esterification of waste oils to biodiesel,under the esterification conditions:temperature 1208℃, v(methanol): v(oleic acid)=1, mass percentage of catalyst relative to oleic acid 6%, time 2h, and the yield of fatty acid methyl ester were all above 94%.The ionic liquids were stable and could be reused.