Biodiesel Production Via Transesterification Using Acidic-functionalized Ionic Liquids As Catalyst

Biodiesel,known as one of the most promising alternative fuel,is renewable,non-toxic and biodegradable,which can alleviate the shortage of energy and improve the ecological environment.Biodiesel is mainly produced by the transesterification using alkali or acid catalysts.However,corrosiveness,environmental pollution and difficult recovery limited the used of these catalysts.Therefore,this paper was investigated in the synthesis of biodiesel via the transesterification of coconut oil/tung oil with methanol using novel Bronsted acidic-functionalized ionic liquids as catalyst,which has favorable properties such as high catalytic activity,repeatability and environmentally friendly.The research focused on the following aspect:(1)Four novel Br(?)onsted acidic-functionalized ionic liquids were synthesized for the first time,which included[PhCH2N1,1PrSO3H][Tos],[PhCH2N1,1PrSO3H][HSO4],[CyN1,1PrSO3H][Tos]and[CyN1,1PrSO3H][HSO4].The structures of those ILs were characterized by using FT-IR,1H NMR,13C NMR.The acidity of those ILs was determined by using the UV-visible spectroscopic and Hammett theoretical model.The result shown that the structures of ILs what we prepared were coincided with the theoretical structure,and the purity of ILs was very high.Furthermore,acidic strength had closely related with their structure,and[CyN1,1PrSO3H][Tos]has the strongest acidity.The solubility of acid-functionalized ILs in the reaction system was measured.(2)The quality of coconut oil/tung oil was determined in terms of their important properties such as density,viscosity,acidic value,saponification value and water content,and average molecular weight was calculated.Furthermore,the oil fatty acid profile was analyzed by gas chromatography.The result shows that coconut oil is mainly composed of 12?14 carbon chain,while tung oil is mainly composed of 18 carbon chain fatty acid.The fatty acid composition in all meets the conditions of the preparation of biodiesel.(3)The synthesis of biodiesel via the transesterification of coconut oil and methanol using acid-functionalized ILs as catalysts were investigated.Among all the tested ionic liquids,[CyN1,1PrSO3H][Tos]performed best,and its catalytic performance was systematically explored by orthogonal experiment based on the single factor experiment.The maximum biodiesel yield of 98.7%was obtained under the optimal reaction conditions:catalyst dosage,4.0 wt%;the initial molar ratio of methanol to oil,15.0;reaction temperature,110 ?;reaction time,2 h;and agitation speed,500 rpm.There was no significant decrease of its catalytic activity after being reused for five successive cycles.(4)The synthesis of biodiesel via the transesterification of tung oil and methanol using acid-functionalized ILs as catalysts were investigated.Among all the tested ionic liquids,[CyN1,1PrSO3H][Tos]performed best,and its catalytic performance was systematically explored by orthogonal experiment based on the single factor experiment.The maximum biodiesel yield of 99.0%was obtained under the optimal reaction conditions:catalyst dosage,5.0 wt%;the initial molar ratio of methanol to oil,21.0;reaction temperature,120 ?;reaction time,2 h;and agitation speed,400 rpm.(5)The synthesis of.biodiesel was refined by washing,drying and vacuum distillation.The quality of refined biodiesel was determined in terms of their important properties such as density,viscosity and acidic value.The result shows that the quality of refined biodiesel meets the American biodiesel standerd(ASTM D 6751-02)...