The Study On Using Quaternary Ammonium Ionic Liquids As Transesterification Catalyst For The Synthesis Of Biodiesel With Rice Bran Oil

Energy is the basic resource for humanity, it is also very important for the economic development and the social development. Being an important strategic material, energy plays a critical role in national security. Today, with the shortage of energy getting more and more serious in the world, many countries are trying to develop renewable energy to enhance their energy security.Biodiesel was synthesized with short chain alcohol and vegetable oils or animal fat by transesterification reaction. An efficient and environmentally friendly production process was in great need. Room temperature ionic liquids have attracted considerable interests because of their potential applications as novel green solvents and catalysts. Studies show that the SO3H-functional ionic liquids are the most acidic Bronsted ionic liquids they are excellent catalysts for transesterification to produce the biodiesel and they have very good industry prospect.Eight kinds of ionic liquids were synthesized in this paper which was supported by the National Science Foundation (20776057), they were [(CH3CH2)2NH(CH2)3SO3H][C7H7O3S],[(CH3CH2)3NH][HSO4],[(CH3CH2)3N(CH2)3SO3H][HSO4],[(CH3CH2)3NH][C7H7O3S],[(CH3CH2)3N (CH2)3SO3H][CH3SO3],[(CH3CH2)3N(CH2)3SO3H][C7H7O3S][(CH3CH2CH2CH2)3N (CH2)3SO3H][C7H7O3S] and [(CH3(CH2)7)3N (CH2)3SO3H][C7H7O3S]. Using IR and NMR to characterize their structure, and their thermal stability were analyzed by using the TGA-DTA method, and at the same time their acidity were analyzed by using UV-VIS spectrophotometry method in which2,4-dinitroaniline were used as the indicator. The eight kinds of ionic liquids were used as the catalysts to prepare the biodiesel, and the [(CH3CH2)3N (CH2)3SO3H][C7H7O3S] showed the best catalytic activity. Then the [(CH3CH2)3N (CH2)3SO3H][C7H7O3S] was used as the catalyst to research its production process. Single-factor experiments were carried out to find the best production conditons:the best reaction time, reaction tempreature, the molar ratio beteween rice bran oil and methyl alcohol,the ionic liquids dosage.The high temperature and high pressure to the ester exchange responded the synthesis biologydiesel oil the craft carried on initially searched. Simultaneously also inspected theionic liquid circulation use number of times to the biodiesel production rate influence.The main content is as following:(1) The ionic liquids’ FT-IR and NMR spectra shows that the ionic liquids werethe target ionic liquids. It also shows that the method of synthesis was correct.(2) From TGA and the DTG curve of the ionic liquid synthsized we know thatthe thermostability of ionic liquid is good, theirs decomposition temperature are allhigher than200℃, they can be used as the catalyst for the preparation of biodiesel.(3) The acidity of eight kinds ionic liquids were studied by UV-VISspectrophotometry method, the results showed that the acidity of functional ionicliquids is more strong than the normal ones; the anion plays an important role on theacidity, at the same time the cation plays less.(4) Four kinds of ionic liquids were choosen for the study of corrosion of metalstest.The results showed that ionic liquids could corroding steel, nickel and copper, butthis corroding is less than para-toluenesulfonic acid.[(CH3CH2)3NH][C7H7O3S]showed the lowest corroding activity;[(CH3CH2)3NH][HSO4] showed the highestcorroding activity;[(CH3CH2)3N(CH2)3SO3H][HSO4] has the same activity withpara-toluenesulfonic acid;[(CH3CH2)3N (CH2)3SO3H][C7H7O3S] has a less corrodingactivity than para-toluenesulfonic acid.(5) The properties of rice bran oil were anaylzed systematiclly. the analysisresult were: Acid value0.83mg KOH·g-1, water content0.333%, saponification value186.02mg KOH·g-1, relative molecular mass901.3797g·mol-1.Main compositionfatty clyceride acids were palmitic acid, linoleic acid and oleic acid.(6) The eight kinds of ionic liquids were used as the catalysts to prepare thebiodiesel, and the [(CH3CH2)3N (CH2)3SO3H][C7H7O3S] showed the best catalyticactivity.(7) Synthesis technics were studied with [(CH3CH2)3N(CH2)3SO3H][C7H7O3S]was used as catalyst.Results showed that with the reaction time was24h, the reactiontemperature was73℃, the molar ratioof methanol and rice bran oil was8:1, molar ratio between ionic liquid and the rice bran oil was1:8.33the yield of biodiesel couldreached to96.3516%。(8) The cycling usage of [(CH3CH2)3N(CH2)3SO3H][C7H7O3S] was investigatedby reduced pressure distillation.[(CH3CH2)3N(CH2)3SO3H][C7H7O3S] was reused for3times, the yield of biodiesel decreased with reuse time increases..(9) High temperature, the high pressure synthesis technics were researched with[(CH3CH2)3N(CH2)3SO3H][C7H7O3S], at the reaction time of4h, the reactiontemperature for140℃, the molar ratio of methanol and rice bran oil was12:1theyield of biodiesel reached92.8402%.Experimental results showed that ionic liquids could be used as the catalyst toprepare the biodiesel with rice bran oil and methanol and the maximum yield ofbiodiesel could reached up to96.2775%.