Research On Fatty Acid Methyl Ester Production By Enzymatic Catalysis

Fatty acid methyl ester is a significant chemical engineering intermediate, which had extensive application area, such as: synthesized multiple surface active agents; served for detergents and other kinds of chemicals; served for the additive of high lubricating oil;,cutting oil,cutting solution and so on. At the present time, the major application of FAME is used as biodiesel to develop. To produce FAME from fatty acid and fat could imply the useful loads for cooking waste oil, so it had the significance of food security. Generally, we used transesterification reaction of oils with methanol to obtain the FAME, based on the characteristic of the catalyst, the production methods of FAME could separate as acid catalysis,base catalysis and enzyme catalysis. Enzyme catalysis was one of the best potential methods, which was equipped with many merits such as low energy consumption,simple recycle,free from contamination and so on. In order to lower the cost of production and improve the efficiency of reaction, the rapeseed oil was used as raw material, the kaitai lipase was catalyst, this article researched on the technological of enzyme catalysis to prepare FAME, the research contents as follows:The condition of free lipase catlysis transesterification was studied. Firstly, chosen the optimum reaction system and the methods of appendding methanol, the reaction system was emulsified system, the methanol was appended in the reaction system by three times. Secondly, to use the yield of FAME as index, analyzed the effect of water quantity, molar ration of methanol to oil, temperature, time,lipase quantity on transesterification by monofactorial tests. On the basis of the monofactorial tests, chosen three more marked factors, water quantity,temperature t,the molar ration of methanol to oil ,then, the response surface methodology was adopt to optimize the transesterification r eaction conditions. The results showed that, the optimized conditions of the reaction was: the reaction time was 16 hours,the lipase quantity was 400IU/g, the water quantity was 21.5%,the temperature is 41℃,the molar ration of methanol to oil is 4.75:1. Under these optimal conditions, the yield of FAME reached 84.02%.The immobilized condition of kaitai lipase was studied. Firstly, to use the activity recovery rate of the immobilized enzyme as index, chosen the carrier material, such as: macroporous resin D101,macroporous resin AB-8,macroporous resin X-5,diatomite,chitosan,sodium alginate.the results showed that the sodium alginate was the optimal carrier material.secondly,designing monofactorial and orthogonal tests to optimize the conditions of the immobilized lipase.The results showed that, the optimal condition was: the consistency of sodium alginate is 1.00%, the consistency of calcium chloride is 12%, the dosage of the lipase is 200IU/g, the outside diameter of the syringe needle is 0. 61mm, Under these conditions the activity recovery rate which was 74.36%.Optimized the immobilized lipase catalyze transesterification reaction of rapeseed oil with methanol which was in emulsified reaction system. The response surface methodology was used to optimize the transesterification reaction conditions, the results showed that, the optimized conditions of the reaction was: the amount of water was 34%, the reaction temperature wais 44℃, molar ratio of methanol and oil was 7.6:1, the reaction time was 20 hours,the quantity of immobilized lipase was 400IU/g.Under these optimal conditions, the methyl ester yield reached 84.89%. When the immobilized enzyme was used five times, the methyl ester ratio could reach 68.35%. This sample was analyzed by GC-MS technique, the results showed that the main component of FAME from rapeseed oil was methyl palmitale,methyl stearate,methyl linoleate,methyl oleate,methyl erucicate and the Content of methyl oleate was the highest.To purify the crude product of FAME, alkali was apendded, inspecting the effect of the dosage of alkali and the initial temperature on acid value. The results showed that when the dosage of alkali is 0.070g/g,the initial temperature is 60℃, the acid value is 0.45mgKOH/g, which reached the standard of acid value of biodesel.Ccomparing the free lipase with immobilized lipase catalysis transesterification: The immobilized lipase put up better survivability than free lipase; When the dosage of the enzyme activity was nearly; the immobilized lipase could reach the same catalytic efficiency; Compared with free lipase, the immobilized lipase could recycle which reduced the output cost.