Esters of free fatty acids-Fatty acid methyl ester - Wikipedia

Those fatty acid esters derived from vegetable fat and oil are used as a cooking oil and, in addition, they are used in such fields as cosmetics and pharmaceuticals. In recent years, attention has been paid to them as additives to fuels such as light oil. For example, they are added as vegetable-derived biodiesel fuel to light oil at addition levels of several percent for the purpose of reducing the emission of CO 2. Glycerine is mainly used in such various fields as a raw material for the production of nitroglycerin and is further used as a raw material for alkyd resins, pharmaceuticals, foods and printing inks and cosmetics. In carrying out such a production method on a commercial scale, a homogenous alkali catalyst is generally used.

Esters of free fatty acids

Esters of free fatty acids

Esters of free fatty acids

Esters of free fatty acids

Esters of free fatty acids

By employing such mode, the step of catalyst separation becomes unnecessary and it also becomes possible to carry out the production process on an industrial scale. In the upper layer, no Ti component was detected and the V component concentration was not higher than 0. When the latter increases, the recovered oil decreases. J; Otero, J. The linear dependence shows that the Arrhenius equation Fred. The peak at cm -1 is assigned to the ester carbonyl group, and the signals at and cm -1 correspond Being just pregnant C-O stretching. The regenerated clay samples showed a similar efficacy in the decolorization of soybean oil than when using a commercial virgin clay.

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From Wikipedia, the free encyclopedia. Fatty acid metabolic intermediates. Yin J. Categories : Carbohydrate chemistry Esters. Insulin sensitivity indices of glucose and free fatty acid metabolism in obese children and adolescents in Esters of free fatty acids Esteers serum lipids. Abstract The study evaluated the profile of circulating fatty acids FA in obese youth with and without metabolic syndrome Corbin blu gay to determine its association with nutritional status, lifestyle and metabolic variables. A simple method for the isolation and purification of total lipid from animal tissues. Ainsworth B. Categories : Fatty acid esters Biodiesel Methyl esters. Journal of the American Oil Chemists' Society. Emulsifiers in Food Technology. By using this site, you agree to the Terms of Use and Privacy Policy. In chemistryparticularly in biochemistrya fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated.

E-mail: malvarezserafini plapiqui.

  • In chemistry , particularly in biochemistry , a fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated.
  • Fatty acid methyl esters FAME are a type of fatty acid ester that are derived by transesterification of fats with methanol.
  • The study evaluated the profile of circulating fatty acids FA in obese youth with and without metabolic syndrome MetS to determine its association with nutritional status, lifestyle and metabolic variables.

E-mail: malvarezserafini plapiqui. This work studies the synthesis of fatty acid methyl esters FAME using crude olive pomace oil as raw material and zinc stearate as catalyst. Pomace oil is a non-edible by-product of olive oil production. The oil was characterized. In order to reduce the plant pigment content in the oil, the liquid was contacted with a modified clay. An experimental design was applied to determine the optimum operating conditions to achieve the minimum pigment concentration and the maximum amount of recovered oil.

Response surface methodology was used to study the relationship between process variables and the selected response variables. A mixed-level factorial design was used, and the studied responses were triglyceride and free fatty acid FFA conversion and FAME yield at 30 min of reaction time.

This study shows that pomace oil can be used as a raw material for biodiesel production. At short reaction times and under moderate operating conditions, it was possible to convert triglycerides and fatty acids selectively toward FAME. Biodiesel is a sustainable alternative to petrodiesel obtained from vegetable oils or animal fats. It emits significantly lower amounts of NOx than petroleum-derived diesel, has better lubricating properties, is biodegradable and less toxic.

Biodiesel consists of a mixture of mono-alkyl esters obtained from the transesterification of triglycerides or the esterification of free fatty acids with short chain alcohols. Argentina is currently one of the leading producers of biodiesel worldwide, using soybean oil as feedstock. Biofuels obtained from human food products are called first generation fuels. In addition to technical aspects, environmental and economic feasibility are also of great importance to access process viability.

The use of vegetable oils suitable for consumption as raw material for biodiesel production has social and economic implications. These include the high costs of high-quality raw materials, the competition between crops for food and for fuel, with the resulting increase in food prices, and the impact on the use of the land Kumar et al.

A cost analysis of biodiesel production using conventional alkali-catalyzed transesterification was carried out by Apostolakou et al. This is in agreement with the results obtained by Haas et al. Marchetti et al. For these reasons, studies are focusing on developing second-generation biodiesel with alternative technologies capable of using low-cost raw materials, as well as non-edible oils and waste from the food industry, such as animal fats and low-quality vegetable oils, or used frying oils Jefferson, ; McKendry, The production of biodiesel from biomass waste reduces the contribution of fuel production to food prices and helps to improve the economic viability of biodiesel Abu-Jrai, ; Vicente et al.

Disposal of alperujo into the soil can cause serious environmental problems because it has phytotoxic activity that does not allow plants to germinate.

Olive plantations in Argentina are expanding rapidly Rousseaux et al. This waste is a good source of bioenergy due to its large calorific value.

It could be used to obtain thermal or electric energy through combustion Roig et al. The environmental impact of biodiesel production from olive pomace oil B20 and B and petroleum diesel were compared through life-cycle assessment Rajaeifar et al.

In addition, energy and economic analyses of biodiesel production from pomace oil were also carried out. They concluded that, among the studied categories, the biodiesel obtained from pomace oil was much better than conventional fuel for the categories climate change and resource damage.

The economic analysis showed the economic viability of biodiesel production from pomace oil. Homogeneous alkaline catalysts, such as sodium and potassium hydroxides and methoxides are used in the industry for the production of biodiesel.

The main drawbacks are the difficulty in using low-cost raw materials due to the presence of free fatty acids FFA and water, and the complexity in the separation and purification stages. Further studies are needed on alternative technologies that may be used with acidic raw materials. Zhang et al. On the other hand, West et al. Homogeneously catalyzed processes require downstream equipment to neutralize the catalyst and also to purify and wash the biodiesel as well as the by-product glycerol.

Heterogeneous catalysts, such as solid acid or base, or immobilized lipases, offer a more environmentally friendly process due to the lack of those stages, and also allow operating with lower investment costs. In the biodiesel production process, a catalyst that is active in both the transesterification and esterification reactions and that can be easily separated from the reaction media can simplify the subsequent purification step.

In previous works Reinoso et al. It is active in the presence of fatty acids and water, and it is non-toxic. One of the current challenges in the second-generation biofuel synthesis is the use of environmentally friendly catalysts that can conserve their activity Hill et al. The novelty of the present manuscript is that it shows the viability of using a very interesting catalyst in the production of biodiesel using biomass waste as feedstock.

This work presents the characterization of pomace oil and evaluates its potential to be used as raw material for the production of methyl esters of fatty acids FAME using zinc stearate as an eco-friendly catalyst under moderate reaction conditions.

Response Surface Methodology was used to study the relationship between process variables temperature, catalyst concentration and initial reactant ratio and triglyceride and free fatty acid conversion and FAME yield. The acid value of pomace oil was determined according to the method described in AOCS Cd 3d, by titration using an ethanolic solution of potassium hydroxide and phenolphthalein as an indicator.

The determination of water in the oil was performed by Karl Fischer titration following the ASTM D method, using the reaction of iodine with water. The peroxide value was determined according to the Official Method AOCS Cd , by titration of the liberated iodine with sodium thiosulphate solution.

The result was expressed in terms of milliequivalents of active oxygen per kg. The content of chlorophyll pigments in pomace oil was determined following the AOCS Official Method Cc 13i, measuring the absorbance at nm, and expressing it as mg of pheophytin a in 1 kg of oil.

In order to know the concentration of phosphorus in the pomace oil, the acid-soluble ashes were obtained according to the AOCS Official Method Ca , from a sample of oil and zinc oxide, dissolving the soluble ashes with hot dilute hydrochloric acid and filtering. The determination of the total phosphorus content was done by inductively coupled plasma ICP spectrometry of the resulting solution.

The pomace oil was purified using a modified clay Tonsil Supreme , donated by Refil S. A to remove the plant pigments chlorophyll. The separation of the pomace oil from the clay was performed by centrifugation.

The factors and levels used and the obtained experimental responses are presented in Table 2. The order of the experiments was fully randomized to protect against the effects of lurking variables. The zinc stearate catalyst was obtained from the metathesis reaction in alcoholic solution Barman and Vasudevan, The sodium stearate salt was prepared first.

The obtained precipitate was dissolved in water, and a stoichiometric amount of ZnCl 2 was added. The reactions were carried out in a ml Parr batch reactor.

The stirring rate was set at rpm to ensure the absence of external mass transfer resistance Reinoso et al. In order to evaluate the effects of the selected variables on the response variables, a 3. The order of the experiments was fully randomized to provide protection against the effects of lurking variables. Catalytic tests were performed for 30 min reaction time for the experimental design, and for min in order to determine equilibrium concentration. The responses were calculated as follows:.

TGE 0 represents the initial equivalent triglycerides moles:. The responses were adjusted by multiple regression, and the generated models were used to evaluate the effect of the selected experimental factors. The goodness of the fit was assessed using the coefficient of determination R 2. A simple kinetic model was utilized in order to model the process. The reaction mixture was assumed to be pseudo-homogeneous, perfectly mixed with no mass transfer limitation Reinoso et al.

According to the assumptions, the reaction rate for the transesterification reaction is:. From the combinations of Eq. Making the same combinations, the equation for the esterification reaction becomes Eq. The catalyst was characterized in order to corroborate the correct synthesis. Figure 1 shows the infrared spectrum a and the XRD pattern b obtained from the catalyst sample.

In Figure 1 a , the strong absorption bands located between and cm -1 correspond to the vibrations of symmetric and antisymmetric deformation of the C-H bond. Additionally, the weak signals between and cm -1 are characteristics of the coupling of the scissoring, rocking and stretching vibrations of the groups CH 2 and CH 3 ,while the signals at and cm -1 correspond to the rocking and scissoring vibrations of the CH 2 group, respectively. The three intense bands located at , and cm -1 are attributed to the coupling of the vibrational modes of symmetric and antisymmetric deformations of the COO- bond of the carboxylic group.

The absorption band located in the region of cm -1 corresponds to the vibration of the O-Zn bond. The diffractogram in Figure 1. The crude alperujo oil has a dark green color and a strong characteristic odor. Figure 2 shows the IR spectrum of the pomace oil and the one corresponding to extra virgin olive oil presented as a reference. The main IR peaks present between and cm -1 are due to asymmetrical and symmetrical C-H stretching, and those at and cm -1 correspond to bending vibrations of C-H Roman and Che Man, ; Lerma-Garcia et al.

The peak at cm -1 is assigned to the ester carbonyl group, and the signals at and cm -1 correspond to C-O stretching. The peaks at and cm -1 are assigned to stretching vibrations of the C-O ester group. The signal at cm -1 corresponds to cis double-bond stretching, while the peak at cm -1 is assigned to trans olefins. No differences were observed between the spectra obtained for the pomace oil and the extra virgin olive oil, except for the signal attributed to trans olefins.

This latter is a consequence of the extraction process of each oil. The chemical composition of the pomace oil, in term of fatty acid composition, is shown in Table 1. The oleic acid is the predominant fatty acid, followed by palmitic acid. It is well known that the vegetable oils used as a raw material for biodiesel production should be almost free of water and FFA since the presence of both of them has negative effects on the transesterification reaction Komers et al.

The measured water content in the crude alperujo oil was 0. Both values are higher than those recommended by Ma et al. The calculated peroxide value was 8.

Untreated crude alperujo oil has poor oxidation stability due to the presence of the high chlorophyll content. This can be improved by pre-treating the oil. The phosphorus content in the oil was 0. Since it is a crude oil, this value corresponds to organic and inorganic phosphorus.

Fatty acid ethyl esters are biomarkers for the consumption of ethanol alcoholic beverages. Acknowledgments Resources were received from Colciencias Contract and from the Universidad de Antioquia — through funds from the Committee for Research Development. Palmitoleic n -7 4. European Journal of Biochemistry. FAME has physical properties similar to those of conventional diesel. Biodiesels are typically fatty acid esters produced by the transesterification of vegetable fats and oils which results in the replacement of the glycerol component with a different alcohol. Instead they are absorbed into the fatty walls of the intestine villi and reassemble again into triglycerides.

Esters of free fatty acids

Esters of free fatty acids

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Those fatty acid esters derived from vegetable fat and oil are used as a cooking oil and, in addition, they are used in such fields as cosmetics and pharmaceuticals. In recent years, attention has been paid to them as additives to fuels such as light oil. For example, they are added as vegetable-derived biodiesel fuel to light oil at addition levels of several percent for the purpose of reducing the emission of CO 2. Glycerine is mainly used in such various fields as a raw material for the production of nitroglycerin and is further used as a raw material for alkyd resins, pharmaceuticals, foods and printing inks and cosmetics.

In carrying out such a production method on a commercial scale, a homogenous alkali catalyst is generally used. It is described that, in carrying out this method, the alcohol is evaporated from the reaction mixture and then the layer containing the free glycerine is separated and removed.

It is also described that when the reaction is carried out continuously, the free alcohol included in the reaction mixture is partly evaporated and then the heavy glycerine phase is separated and removed by phase separation, part of the light ester phase is returned to the transesterification step as a recycling stream and the evaporated alcohol and fresh portions of the reactants are simultaneously introduced into the same step.

There is no description of the use of a catalyst in carrying out this method; the reaction is carried out at high temperatures and under high pressure. In this process as well, the reaction is carried out at high temperatures and under high pressure. It is described, in the examples, that a methanol slurry containing a MnO 2 powder suspended therein is fed and that the monohydric alcohol is fed in an amount of about 17 times the theoretical amount to be fed.

This composite metal oxide containing a perovskite-type structure is highly basic and preferably contains a cesium Cs compound. However, when such composite metal oxides having a perovskite-type structure are used, high reaction temperature is required, since pure perovskite is low in activity.

High reaction temperatures allow the elution of the active ingredients of the catalysts. However, a problem arises; such active metal components as Ca and Cs are eluted into the liquid reaction mixture in large quantities. Thus, they came to realize that the above object can be skillfully accomplished in the above manner. Such and other findings have now led to completion of the present invention.

Thus, an operation mode more advantageous from the production viewpoint can be selected from 1 the operation mode in which the reaction is carried out in one step to thereby reduce the energy consumption of the production and the ester phase and glycerine phase finally obtained are distilled and purified and 2 the operation mode in which the reaction is carried out in multiple steps advantageously from the chemical equilibrium viewpoint while separating the by-product water generated from esterification and the product glycerine resulting from transesterification in the manner of phase separation to thereby improve the conversion and simplify the purification process.

Further, in the process of completion of the present invention, it was found that a catalyst containing, as an essential constituent, at least one metal element selected from the group consisting of the metal elements belonging to the Group 4 and the Group 5 in the periodic table is capable of catalyzing esterification and transesterification simultaneously, and unaffected by a mineral acid or metal components contained in a fat and oil and, further, capable of producing such effects as the nonoccurrence of decomposition of the alcohol, and that the use of such a catalyst makes it possible to carry out the reaction efficiently at high activity levels and under mild conditions and thus produce the desired products advantageously from the energy viewpoint while reducing the energy consumption of the production.

Furthermore, it was found that when such an insoluble solid catalyst is used, the active metal components are eluted little, the catalyst life-time is sufficiently long, the catalyst recovery step can be much simplified as compared with the current processes using a homogeneous catalyst, and the catalyst can be used repeatedly for the reaction, so that the desired products can be produced advantageously from the energy viewpoint while reducing the energy consumption of the production.

In the following, the present invention is described in detail. In accordance with the present invention, a fat or oil is reacted with an alcohol using an insoluble solid catalyst.

In the case of producing fatty acid alkyl esters in addition to the effects mentioned above, the fatty acid alkyl esters content in the ester phase is improved due to the improvement in conversion and in recovery of the fatty acid alkyl esters from the glycerine phase, so that the purification cost can be reduced.

Further, unlike the conventional methods of production using a homogeneous catalyst, the step of catalyst removal by washing with water becomes unnecessary; in this respect, the method of the invention is an advantageous one. In the case of production of glycerine as well, recovery of glycerine from the ester phase is improved and high concentration and high purity levels of glycerine in the glycerine phase can be attained because of no necessity of diluting with water, so that the purification cost can be reduced.

Furthermore, in the case of simultaneous production of fatty acid alkyl esters and glycerine, it becomes possible to produce the respective effects simultaneously. In addition, the ester or fatty acid obtainable by the present invention is generally a mixture, but they may also be single compounds. Thereafter, fatty acid alkyl esters and glycerine are separated from the low-boiling components removed liquid obtained by removing the low-boiling component or fraction from effluent of the last reactor.

That is, in the present invention, after the step comprising removing the low-boiling components or fraction from the reaction mixture after the one-stage reaction in the absence of a catalyst, a step comprising phase separation of the ester phase and glycerine phase is included. That is, in the present invention, after the step comprising removing the low-boiling components or fraction from the reaction mixture of the last reaction step in the absence of a catalyst, a step comprising phase separation of the ester phase and glycerine phase is included.

In a preferred mode of carrying out the above-mentioned method of production, the glyceride and free fatty acids separated and removed from the product fatty acid alkyl esters and glycerine are reused together with the raw material fat or oil. The phase separation into the ester phase and glycerine phase is preferably caused by allowing to stand, centrifugation, or using a settle or liquid cyclone, and others.

It is also possible to employ the mode in which it is allowed that the effluent from the last reactor is separated into two phases of the ester phase and glycerine phase and a low-boiling component or fraction is removed from each phase in the absence of the catalyst.

The concentration of the active metal component in the reaction mixture eluted from the catalyst can be determined by subjecting the effluent from the reactor in the solution form to X ray fluorescence analysis XRF. When further smaller elution is determined, inductively coupled plasma ICP emission spectrometry is used.

The ester phase obtained in the step of phase separation of the low-boiling components removed liquid into the ester phase and glycerine phase preferably contains not less than 75 parts by weight of fatty acid alkyl esters per parts by weight of the ester phase.

At levels lower than 75 parts by weight, the energy consumption of the production system may not be decreased to a satisfactory extent. More preferably the content level is not lower than 85 parts by weight and still more preferably not lower than 90 parts by weight. The glycerine phase obtained in the step of phase separation of the low-boiling components removed liquid preferably contains not less than 70 parts by weight of glycerine per parts by weight of the glycerine phase.

At levels lower than 70 parts by weight, the energy consumption of the production system may not be decreased to a satisfactory extent.

More preferably the content level is not lower than 80 parts by weight and still more preferably not lower than 85 parts by weight. In accordance with the present invention, the concentration of the active metal component of the insoluble solid catalyst, which is contained in an effluent from the last reactor, is not more than 1, ppm.

At levels exceeding 1, ppm, it will become impossible to inhibit the reverse reactions to a satisfactory extent, hence it will be impossible to reduce the energy consumption of the production to a satisfactory extent. The limit level is preferably not higher than ppm, more preferably not higher than ppm and still more preferably not higher than ppm.

Most preferably, the effluent liquid from the last reactor should be substantially free of any active metal component of the insoluble solid catalyst. In the above-mentioned case of production in two or more reaction stages, the mode is preferred which includes a step of reaction of the ester phase separated from the effluent of the reactor with the alcohol in the next reactor in the presence of the insoluble solid catalyst. Thus, preferably, the ester phase is separated and recovered from the liquid reaction mixture resulting from the preceding reaction stage and the reaction in the next stage is carried out using the ester phase recovered and the alcohol as reactants in the presence of the insoluble solid catalyst.

In such a mode, the separation of the ester phase and glycerine phase from each other can be improved. In the above case, when two successive reaction stages are taken into consideration, the preceding reaction stage means the reaction stage which is carried out first, while the next or succeeding reaction stage means the reaction stage which is carried out later.

Thus, in the case of two-stage reactions, the first stage is the preceding reaction stage and the second stage is the next or succeeding reaction stage. In the case of three-stage reactions, when the first and second reaction stages are taken into consideration, the first reaction stage is the preceding reaction stage and the second stage is the next or succeeding reaction stage and, when the second and third reaction stages are taken into consideration, the second stage is the preceding reaction stage and the third stage is the next or succeeding reaction stage.

By employing such a multistage reaction process, it becomes possible to drive the esterification and transesterification reactions almost to completion and, thus, it becomes possible to simplify the purification step to be carried out later. At levels higher than 5 times, the amount of the alcohol to be recovered and recycled increases, hence the energy consumption of the production may be not reduced to a satisfactory extent.

The lower limit is more preferably 1. The upper limit is more preferably 4. A more preferred range is 1. A range of 1. In this case, the preceding reaction stage means the first reaction stage out of two or more reaction stages. In a preferred mode of carrying out the production method of the invention, it comprises a step of distillation purifying at least one of the ester phase and the glycerine phase obtained in the step of phase separation of the low-boiling component reduced liquid, wherein at least one of the purification residues is used as one of the raw materials for the reaction.

Also preferred is the mode in which the alcohol is recovered from the low-boiling components or fraction distilled off and at least part of the recovered alcohol is used as a raw material. By employing such a mode or modes, it becomes possible to cut down the production cost to a satisfactory extent.

The process may comprise one or more steps other than the steps mentioned above and, further, includes not only the case where both the one reaction stage mode and two or more reaction stage mode mentioned above are carried out as selected appropriately but also the case where one of the both modes alone is carried out.

For the distillation of the ester phase and glycerine phase and for the recovery of the alcohol any of those methods known in the art may be appropriately employed, and the distillation and recovering temperatures can be properly selected according to such factors as the fatty acid alkyl esters species to be produced and the alcohol species to be recovered.

In cases where the alcohol is recovered from the low-boiling components or fraction distilled off as mentioned above and at least part of the recovered alcohol is used as a raw material, it is allowable to use at least part of the recovered alcohol as a raw material, and it is preferable to use all parts of the recovered alcohol as a raw material in the economical viewpoint.

It is also desirable that the alcohol be purified by distillation, for instance, to remove impurities prior to reuse. When the alcohol to be reused as a raw material contains water, the yield of the fatty acid alkyl esters may decrease in some instances due to the progress of hydrolysis of the fatty acid alkyl esters in the reaction step.

The water content in the alcohol is generally not lower than 0. As the water content decreases, the fatty acid alkyl esters can be obtained more advantageously from the equilibrium of hydrolysis viewpoint. At water content levels below 0. As for the production mode in the practice of the invention, either the batch method or continuous flow method may be employed. The fixed bed flow method is preferred, among others. As the reactor to be used in such a production mode, there may be mentioned tubular reactor, stirring slurry reactor, and reaction kettle type ones, among others.

By employing such mode, the step of catalyst separation becomes unnecessary and it also becomes possible to carry out the production process on an industrial scale. When such a fixed bed reaction apparatus as mentioned above is used, the average time of residence of the liquid reaction mixture in the reaction apparatus is preferably not shorter than 1 minute and not longer than 5 hours.

A shorter time than 1 minute may be insufficient for allowing the reaction to proceed to a satisfactory extent, while a longer time than 5 hours may require a large-sized reaction apparatus.

More preferably, the residence time is not shorter than 2 minutes and not longer than 4 hours, and still more preferably not shorter than 5 minutes and not longer than 3 hours. Now, referring to FIG. It goes without saying that the present invention is not restricted to these modes.

In such a mode, the raw material methanol is fed from a methanol reservoir 1 to a reactor 4 via a line , and the supply thereof is 1 to 5 times the theoretical one. The liquid reaction mixture thus obtained contains methyl esters, glycerides, free fatty acids, methanol, glycerine and by-product water, among others, and the content of the eluted active metal component of the insoluble solid catalyst therein is not higher than 1, ppm.

The liquid reaction mixture is fed from the bottom of the reactor 4 to a column 5 for stripping off a low-boiling fraction a light ends column 5 via a line In the light ends column 5 , the above liquid reaction mixture is deprived of low-boiling components or fraction comprising methanol and byproduct water, and the low-boiling components or fraction distilled off is sent to a methanol recovery column 6 through a line The high-boiling fraction obtained by removal of the low-boiling components or fraction from the liquid reaction mixture low-boiling component removed liquid is sent to a separator 7 via a line In the methanol recovery column 6 , the low-boiling components or fraction is separated into methanol and byproduct water, and the methanol is fed to the reactor 4 via a line and thus is reused as a reactant raw material.

In the separator 7 , the high-boiling fraction is allowed to stand, whereby it undergoes phase separation into an ester phase and glycerine phase.

The ester phase is sent to an ester purification column 8 via a line , while the glycerine phase is sent to a glycerine purification column 9 via a line In the ester purification column 8 , the desired final product fatty acid alkyl esters are obtained by distillation through a line while the purification residue is fed to the reactor 4 through a line for reuse as a reactant raw material.

In the glycerine purification column 9 , the desired final product glycerine is obtained by distillation through a line , and the purification residue is fed to the degumming reactor 3 via a line and reutilized as a reactant raw material. In another preferred mode of embodiment, the light ends column 5 is used also as the methanol recovery column and thus the methanol recovery column 6 is omitted, and the byproduct water is recovered at the bottom of the light ends column 5.

In this case, the light ends column 5 is operated as a methanol recovery column, and the byproduct water may be removed, for example, in a dehydration column additionally disposed between the glycerine purification column 9 and separator 7 or, without adding any dehydration column, the byproduct water may be removed from the top of the glycerine purification column 9 while purified glycerine may be obtained by side-cut or partial condensation at the top of the column 9.

In such a mode, the raw material methanol is fed from a methanol reservoir 10 to a first stage reactor 13 via a line The liquid reaction mixture obtained contains methyl esters, glycerides, free fatty acids, methanol, glycerine and water, among others, and is sent from the bottom of the first stage reactor 13 to a separator 14 via a line In the separator 14 , the reaction mixture is allowed to stand, whereupon it undergoes phase separation into an ester phase and glycerine phase.

The ester phase is sent to a second stage reactor 15 via a line This ester phase contains fatty acid alkyl esters, glycerides, free fatty acids and methanol. On the other hand, the glycerine phase containing glycerine, methanol and byproduct water is sent to a line via a line In the second stage reactor 15 , the ester phase derived from the separator 14 reacts with fresh methanol supplied from the methanol reservoir 10 via the line The liquid reaction mixture is sent from the bottom of the second stage reactor 15 to a light ends column 16 via the line , together with the glycerine phase derived from the separator 14 mentioned above.

In the light ends column 16 , the low-boiling components or fraction containing methanol and byproduct water is distilled off from the reaction mixture, and the low-boiling components or fraction distilled off is sent to a methanol recovery column 17 via a line The high-boiling fraction obtained after removal of the low-boiling components or fraction from the reaction mixture low-boiling component removed liquid is sent to a separator 18 via a line

Esters of free fatty acids

Esters of free fatty acids