Research On Biodiesel Production By Lipase In Reversed Micellar Systems

Object:The article research the technology of biodiesel synthetize for use lipase catalyzecottonseed oil in water/AOT(succinic acid-2-ethyl hexyl sodium sulfonate)/isooctanereverse micelle system, aims to use reverse micelle system to explore optimal condition oflipase catalysis cottonseed oil with various acyl receptors synthesis biodiesel,explore theeffect of biodiesel synthesis process with the methanol, dimethyl carbonate, methyl acetateas three different acyl receptors respectively. Respectively by FAME(Fatty Acid MethylEster) conversion and the content of reaction by-product glycerine as the index, observeand study the effect of the multiple influence factors of ester exchange reaction, andthrough the orthogonal experiment get the optimization reaction conditions of esterexchange reaction.Methods:Separately use methanol, dimethyl carbonate and methyl acetate with lipase catalyzecottonseed oil synthetize biodiesel in water/AOT/isooctane reverse micelle system. Usingthin layer chromatography and HPGC to the biodiesel to carry on quantitative andqualitative analysis, and at the same time, by means of single factor experiments andorthogonal experiment to optimize ester exchange reaction process conditions, analysis thecatalytic efficiency and lipase reuse times in the condition of three kinds of acyl receptors.Results:1. In the reverse micelle system, with methanol as acyl receptor, free lipase as catalyticcatalyze cottonseed oil synthetize biodiesel, on the basis of single factor experiments,through the orthogonal test to determine the optimal reaction conditions of methanol asacyl receptor biodiesel synthetize.The result that is: when the AOT concentration for50mmol/L, buffer pH for4, reaction temperature35℃, substrate molar ratiofor4, lipasedosage for10mg, table speed for160r/min, W0(moisture content) for5, the fatty acidmethyl ester conversion is73.4%. At the same time obtain seven factors on the influenceof the ester exchange reaction size is as follows: the table speed> reaction temperature>AOT concentration> lipase dosage> buffer pH> substrate molar ratio> W0. 2. In the reverse micelle system, with dimethyl carbonate as acyl receptor, free lipase ascatalytic catalyze cottonseed oil synthetize biodiesel, on the basis of single factorexperiments, through the orthogonal test to determine the optimal reaction conditions ofmethanol as acyl receptor biodiesel synthetize.The result that is: when the AOTconcentration for60mmol/L, buffer pH for7, reaction temperature25℃, substrate molarratio for4, lipase dosage for10mg, table speed for120r/min, W0(moisture content) for5,the fatty acid methyl ester conversion is66.2%. At the same time obtain seven factors onthe influence of the ester exchange reaction size is as follows: W0> AOT concentration>substrate molar ratio> lipase dosage> the table speed> buffer pH> reaction temperature.3. In the reverse micelle system, with methyl acetate as acyl receptor, free lipase ascatalytic catalyze cottonseed oil synthetize biodiesel, on the basis of single factorexperiments, through the orthogonal test to determine the optimal reaction conditions ofmethanol as acyl receptor biodiesel synthetize.The result that is: when the AOTconcentration for50mmol/L, buffer pH for9, reaction temperature45℃, substrate molarratio for3, lipase dosage for15mg, table speed for140r/min, W0(moisture content) for5,the fatty acid methyl ester conversion is62.35%. At the same time obtain seven factors onthe influence of the ester exchange reaction size is as follows: lipase dosage> buffer pH>substrate molar ratio> reaction temperature> W0> the table speed> AOT concentration.4. Under the optimal reaction conditions, when the methanol as acyl receptor withcottonseed oil synthetize biodiesel, the lipase activity can maintain three batches, affter thethird batch ester conversion decreases evidently; Dimethyl carbonate as acyl receptor,lipase activity can maintain4batches, affter the4th batch ester conversion is decreased,but the rate of descent is not like methanol as acyl receptor as obvious but slow; Methylacetate as acid receptor, lipase activity can maintain7batches, after the7th batch esterconversion rate of decline is not obvious, until ahhter the ninth batch declined obviously.Conclusion:1. Useing methanol, dimethyl carbonate and methyl acetate three linds of acyl receptorswith lipase catalyzed cottonseed oil synthetize biodiesel. And use of HPGC and thinlayer chromatography to carry on qualitative and quantitative analysis for the product.2. Using single factor experiments and orthogonal experiment analyse the influence of theester exchange reaction on table speed, reaction temperature, AOT concentration,enzyme dosage, pH buffer, substrate molar ratio, W0etc. factors, and obtain the optimization reaction conditions of biodiesel synthesis with three different acylreceptors.3. Methyl acetate as acyl receptor, the ester exchange reaction conversion relative tomethanol and dimethyl carbonate is lower, but the stability of lipase in methyl acetatesystem is higher than that of methanol and dimethyl carbonate system obviously, it isimply that methyl acetate has the big potential on the synthesis of biodiesel as acylreceptor.4. Compared with the traditional methods of biodiesel synthesis, using lipase catalyzecottonseed oil synthetize biodiesel in reverse micelle have the preponderance of providean appropriate microenvironment for the reaction, the requirement of raw material is lowand easy to acquire, process no pollution and many other advantages, comply withenvironmental friendly target. But compared with traditional methods, the reaction in thissystem need more longer time and the conversion rate is lower, but it in general belongto a good reaction system, in the future should reaearch the reaction kinetics further tosolve the low conversion shortcoming...