OA16814A - Ecological process for the production of ethanolic esters by ethanolic transesterification in enzymatic catalysis. - Google Patents

Abstract

Process for the production of ethanolic esters by transesterification of triglycerides of a vegetable oil or of an animal fat with ethanol, according to the reaction: triglycerides + ethanol ethanolic esters + glycerol, this reaction being catalyzed by a plant enzyme, this process comprising : the gradual introduction of ethanol into the reaction medium; - the introduction of silica into the reactive medium to achieve the absorption of at least part of the glycerol produced.

Description

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Ecological process for the production of ethanolic esters by ethanolic transesterification in enzymatic catalysis

The invention relates to the production of ethanolic esters (intended in particular for use as biodiesel) by alcoholic transesterification of the triglycerides of a vegetable oil or an animal fat, according to an ecological process.

Ethanolic esters produced from vegetable oil or animal fat are the subject of much research because, used as biodiesels, they are an advantageous substitute for fossil fuels by being both renewable and less polluting.

This substitution is all the more advantageous as it does not require any particular adaptation of the diesel engines.

Recall that transesterification takes place according to a reaction in which the triglycerides contained in the oil or fat react with an alcohol to form alcoholic esters - as the main product of the reaction - and glycerol - as as a byproduct of the reaction.

We simplify the reaction by writing it as follows:

Triglycerides + alcohol -> alcoholic ester + glycerol

In order to accelerate this naturally slow reaction and increase its naturally low yield, it is common practice to add a catalyst to the reactive medium.

But the transition from laboratory production to industrial scale remains problematic. Arbitrations must be made as to the following criteria:

the choice of oil or fat, the choice of alcohol, the choice of catalyst,

- operation mode.

The choice of oil or fat is not obvious. Many oilseeds, whether in grain or fruit, can be used as a basis for the preparation of esters. Examples include soybeans, sunflowers, mahua (or madhuca), babassu, jatropha, grape seed. These examples are listed in L. Fjerbaek, A Review of the Current State of Biodiesel Production Using Enzymatic Transesterification, Wiley InterScience, 8 Jan. 2009. It is also possible to use mixtures or even

D019 8002 OA Version: TQD gtfptfCATh residues of cooking vegetable oil. Many constraints of an economic, ethical and industrial nature weigh on the choice of oil. It is economically and ethically reasonable to use locally produced oilseeds, when these are not taken from food stocks, ideally if these oilseeds are grown on unsuitable soils. cereal or market gardening. Among these oilseeds, jatropha curcas turns out to be an interesting plant, because it combines good resistance to drought and a high content of triglycerides (present in its 10 seeds).

The choice of alcohol is simpler and is generally waxed between methanol and ethanol. Methanol is widely used because of its relatively low production cost. However, methanol, obtained from the petrochemical industry, has an unfavorable carbon footprint, associated with neurotoxic properties, which make it unsuitable for ecological processes for the production of esters. Ethanol, on the other hand, can be easily extracted from biomass, typically in the sugar industry, without causing major environmental or health problems. However, it is little used because of its low reactivity in the transesterification reactions of triglycerides compared to methanol, and because of its hydrophilic character: common ethanol is generally loaded with water (up to 5% by volume). . However, the presence of water in ethanol tends to at least partially deactivate the catalyst and promotes the occurrence of counterproductive side reactions (typically the hydrolysis of esters). It is possible to dehydrate ethanol, but this operation is expensive and consumes a significant part of the energy contained in the ethanol itself.

The choice of catalyst is delicate. There are two types of catalysis: chemical catalysis (acidic or basic, homogeneous or heterogeneous); enzymatic catalysis.

Homogeneous basic catalysis consists in using a catalyst dissolved directly in the reaction medium. Based on catalysts such as sodium hydroxide (NaOH), potassium hydroxide (KOH) or even sodium ethanoate (EtO Na *), this catalysis is the most common because it is the simplest to carry out. Besides his

D019 8002 OA

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appearance of side reactions of hydrolysis and saponification resulting in lower yield, except for using ethanol in anhydrous form, associated with a purified vegetable oil having a low fatty acid content (favorable to saponification reactions) , the need, in certain cases, to carry out the reaction at an elevated temperature, above 60 ° C to avoid the formation of emulsions unfavorable to the separation of alcoholic esters and glycerol, the need to purify the reaction product to extract the catalyst still present.

Heterogeneous catalysis (acidic or basic), which is less common, consists in immobilizing the catalyst on a fixed surface. This process does not require neutralization of the catalyst at the end of the reaction, the latter being able to be recovered by filtration. Heterogeneous catalysis turns out to be less polluting than homogeneous catalysis. However, it is less efficient due to the reduced availability of reactive sites and requires high temperatures, above 150 ° C, and also high pressures (up to 25 bars), to the detriment of the energy efficiency of the unit. production.

Enzymatic catalysis is an increasingly studied alternative to chemical catalysis. Lipases, also known as triacyIglycerol hydrolases (also known under the code number EC 3.1.1,3, assigned by the Enzymes Commission), are enzymes ensuring the metabolism of lipids in living beings, plants or animals. The advantage of lipases is their effectiveness at mild temperature and pressure (room temperature or not exceeding 45 ° C, atmospheric pressure). Secondary saponification reactions are avoided because, as Fjerbaek (op.cit.) Points out, lipases (at least microbial lipases) carry out the joint esterification of triglycerides and free fatty acids.

Enzymatic catalysis, however, suffers from constraints linked to the difficulty of going from the laboratory scale to the industrial scale.

First, glycerol, a by-product of the transesterification reaction, can have an inhibitory effect on catalytic activity.

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OtfPttrAÏ * lipases. Second, the preparation of lipases is relatively tedious, the cost of which limits the economic benefit of using these enzymes. The literature has studied the effects of both microbial and plant lipases, with a predominance of the former, available in commercial form, cf. Fjerbaek (op.cit.).

Despite the complexity and high cost of their production, microbial lipases are frequently employed due to their good catalytic efficiency. The use of plant enzymes is rarer (although these meet biological requirements), due to their apparent lower efficacy than that of microbial lipases.

The use of plant enzymes for the production of esters by ethanolic transesterification of vegetable oil has however been studied, cf. G. Nahak, Comparative study of enzymatic transesterification of Jatropha oil using lipase from Jatropha curcas and Jatropha gossipyfolia, Continental J. Blological Sciences, 2010.

This publication nevertheless suffers from a lack of clarity as to the results obtained, and provides few details, in particular on the protocol for the analysis of the esters obtained, the quality of which one can reasonably doubt.

A first objective of the invention is to provide an ecological process for the production of esters by alcoholic transesterification of the triglycerides of a vegetable oil or of an animal fat.

A second objective of the invention is to provide a process for producing esters which, while remaining ecological, has a good yield,

A third objective of the invention is to provide a process for the production of esters which, while having a good yield, can be carried out under mild conditions of temperature and pressure.

A fourth objective of the invention is to provide a process for the production of esters which, having a good yield under mild temperature and pressure conditions, can be transposed to an industrial scale.

To this end, a process is proposed for the production of ethanolic esters by transesterification of triglycerides of a vegetable oil or of an animal fat with ethanol, according to the reaction:

Triglycerides + ethanol -> ethanolic esters + glycerol i

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Otf Pt. T C A ï A this reaction being catalyzed by a plant enzyme, process in which:

the ethanol is introduced gradually into the reactive medium;

silica is introduced into the reactive medium to effect the adsorption of at least part of the glycerol produced.

Various characteristics of this process can be provided, alone or in combination:

the introduction of the ethanol is carried out in at least two successive stages each consisting in introducing a fraction of the stoichiometric proportion of ethanol necessary for the total consumption of the oil.

the enzyme is derived from sprouted seeds of Jatropha Curcas;

the catalyst introduced into the reactive medium is in the form of a powder of sprouted seeds of delipidated Jatropha Curcas;

the reaction is carried out at a temperature between 35 ° C and 40 ° C;

the reaction is carried out at atmospheric pressure;

the ethanol is introduced into the reaction medium in a molar ratio to the oil or to the fat of between 1: 0.3 and 1: 0.9;

the catalyst is introduced into the reaction medium according to a catalyst / oil or fat mass ratio of between 10% and 20%; ethanol is partially hydrated;

ethanol has a water content of about 5%.

Other objects and advantages of the invention will become apparent in the light of the description of embodiments of a process for the production of ethanolic esters in particular intended for use as biofuel (commonly called biodiesel, due to its substitution - or of its mixture - possible with current diesel from the petrochemical industry) by transesterification of triglycerides from vegetable oil or animal fat to produce a biofuel. It will be noted that the ethanolic esters can also have applications, in particular in cosmetics, where they can play a role of chemical intermediary.

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Remember that triglycerides, which are the main constituents of vegetable oils and animal fats, and which are also called triacylglycerols or triacylglycerides, are lipids belonging to the family of glycerides (formed by a combination of fatty acid esters and glycerol). In a triglyceride, three hydroxyl groups —OH of glycerol HOH ₂ C-CHOH-CH ₂ OH are linked by esterification to three fatty acids. The chemical formula of a triglyceride molecule is generally characterized as follows:

ch ₂ -o-co-r ₁

I ch-o-co-r ₂

I ch ₂ -o-co-r ₃ where R _b R ₂ and R ₃ are fatty acids.

The transesterification reaction of a triglyceride is activated by an R-OH alcohol. The fatty acids of its molecule each react with an alcohol molecule to give respectively, on the one hand, three mono alcoholic esters (main products of the reaction) and, on the other hand, glycerol (by-product of the reaction , intended to be separated from esters), depending on the reaction:

CH ₂ -O-CO-R1 1 R-O-CO-Ri -4- CH ₂ -OH 1 CH-O-CO-R ₂ + I 3-R-OH -> RO-CO-R2 + ro-co-r ₃ + 1 CH-OH I 1 CH ₂ -O-CO-R ₃ 1 ch ₂ -oh

The alcohol is ethanol CH ₃ -CH ₂ -OH, which has the advantages of being non-toxic, of having a low impact on the greenhouse effect, and of being able to be produced by distillation of the product from aerobic fermentation of any sweet or starched biomass, which is renewable by nature,

The reaction of transesterification of triglycerides by ethanol produces ethanolic esters and glycerol, according to the following reaction:

triglycerides + ethanol - »ethanolic esters + glycerol

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For the reasons explained in the introduction, this reaction is carried out in the presence of an enzymatic catalyst, and more precisely a plant enzyme, and in particular a lipase, within the meaning of the Cavalier-Smith six-kingdom living classification, as published in T. Cavalier-Smith, A revised six-kingdom System of life, Biological Reviews, Cambridge Philosophical Society, Vol. 73, No. 3, August 1998, p.203-266, and resumed in T. Cavalier-Smith, Only six kingdoms of life, Proc. R. Soc. Lond. B, Vol. 271, No. 1545, June 22, 2004, p.1251-1262.

Tests have shown that the catalytic function is particularly effective when the enzyme (lipase) is extracted from sprouted seeds of Jatropha, and in particular from the variety Jatropha Curcas.

The germination of Jatropha Curcas seeds can be carried out in a conventional manner. A typical germination protocol may include the following:

hydrate the raw seeds (obtained after crushing, taking care to break the fruit shells without damaging the seeds they contain) by immersing them in a water bath, after hydration of the seeds, place them in a humid environment at a regulated temperature (for example at about 20 ° C), after appearance of the germ (that is to say when the radicle has pierced the cuticle of the seed), keep the germinated seeds in the humid environment for a predetermined period, advantageously between 72 and 96 hours to obtain a germ of reasonable size (of the order of 1 cm or more) and promote enzymatic activity.

It has in fact been shown that the enzymatic activity of Jatropha curcas seeds is optimal approximately 96 hours after germination, cf. R. Staubmann, Esterase and lipase activity in Jatropha curcas L. Seeds, Journal of Biotechnology 75 (1999) 117-126.

The sprouted seeds of Jatropha Curcas undergo, prior to their use as a catalyst in the transesterification reaction, conditioning comprising:

a first operation of crushing the sprouted seeds (for example by means of a mill or a roller mill) to

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OLIPt ï CA ï To obtain a fine vegetable powder (with grains of size less than approximately 0.5 mm), a second operation of drying the vegetable powder thus obtained, preferably carried out at a gentle temperature (less than or equal to 40 ° C, typically around 35 ° C), a third operation of delipidization of the vegetable powder thus dried. This delipidation is preferably carried out chemically. According to one embodiment, the delipidation is carried out by mixing hexane with the vegetable powder, then by centrifugation of the mixture, and finally by filtration and drying of the centrifugation residue, which is in the form of a delipidated vegetable powder.

For reasons of simplicity, the term “catalyst” is used twice: from a functional point of view, to designate the enzyme as a catalyst for the transesterification reaction and, from a structural point of view, the vegetable powder. delipidated according to the process described above.

Transesterification reaction tests of a vegetable oil were carried out using the catalyst thus produced, varying the following parameters to determine the optimum values:

the vegetable oil (or animal fat) / ethanol molar ratio, denoted HV: EtOH the water content (by volume) of the ethanol, denoted H ₂ 0% the catalytic load - i.e. the catalyst / mass ratio vegetable oil (or animal fat), denoted Cat%.

The tests have shown that the water content H ₂ 0% of the ethanol has little influence on the yield of the reaction.

This finding is positive because, given the difficulties encountered in dehydrating ethanol (particularly hydrophilic), the production of ethanolic esters on an industrial scale with dehydrated ethanol (that is to say with a lower water content or equal to 0.5%), could thus be discarded from the outset in favor of production using a partially hydrated ethanol of commercial quality, in which the water content is approximately 5%.

Regarding the HV parameters: EtOH and Cat%, the tests made it possible to determine ranges of values, outside of which, which

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WPUCAO whatever the other parameters (in particular temperature, pressure, procedure), the transesterification reaction cannot be carried out satisfactorily because of yields (that is to say of conversion rate of triglycerides into ethanolic esters) too weak.

These ranges are as follows:

Min Max

HV: EtOH 1: 0.3 1: 0.9

Cat% 10% 20%

In particular, it has been observed that the yield of the transesterification reaction varies inversely with the HV: EtOH molar ratio when the ethanol is introduced into the reactive medium all at once. In particular, when the ethanol is introduced all at once with an HViEtOH molar ratio greater than or equal to 1: 0.6, the yield of the transesterification reaction turns out to be very low (in practice less than 20%).

On the other hand, an increase in the yield of the transesterification reaction with the catalytic charge Cat% is observed. However, it appears preferable to moderate the catalytic charge, because of the economic and energy costs of manufacturing the catalyst. Too high a load would adversely affect the overall efficiency (including the energy costs of producing raw materials).

Several examples of a process for the production of ethanolic esters by transesterification of the triglycerides of a vegetable oil (which also contains monoglycerides and diglycerides) are presented below. In all of these examples, the oil is sunflower oil, but it could be another vegetable oil (especially soybean, Jatropha, grapeseed, a mixture of various vegetable oils), or still animal fat. The alcohol used is commercial grade ethanol with a water content of approximately 5%. These examples, carried out on an experimental basis on small quantities of reagents, aim to determine the best operating conditions and the best choices for the reaction parameters.

Example 1

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In this first example, 4 g of sunflower oil and 690 μl of hydrated ethanol (at 5%) are brought together in a flask with a capacity of 25 ml, i.e. an HV: EtOH molar ratio of 1: 3.6. The ethanol is added in successive 80 µl fractions at predetermined intervals (eg every 6 hours) - twelve fractions. The reaction is carried out in the presence of a mass of catalyst of 0.4 g (i.e. a catalytic load of 10%), in an oven maintained at a temperature between 35 ° C and 40 ° C (in this case at 37 , 5'C), at atmospheric pressure, with orbital stirring, for a period of 72 hours. The catalyst is added directly to the reaction medium, without solvent.

The yield of the reaction is measured by chromatography. More precisely, after 72 hours of reaction, a sample of 44 μl is taken from the reaction mixture and undergoes a heat treatment (for example in an oven or in a water bath at a temperature greater than or equal to 90 ^e C so as to inactivate the enzymes After this heat treatment, the sample is cooled to room temperature, then a quantity of n-hexane of a few ml (typically 4 ml) is added to it. 100 μl of this solution are diluted in a few ml (in this case 10 ml) of n-hexane. From this mixture, a 10 μl sample is taken and then analyzed by chromatography, optionally coupled to a densitometric measurement, to measure the quantity of ethyl esters present therein, then calculate the quantity of ethyl esters. in the reaction medium, then related to the quantity of ethanol introduced to deduce the yield R therefrom, according to the following formula:

n EEHV (3 * n TAG + 2 * nDAG + nMAG) * ¹⁰⁰

OR :

nEEHV is the number of moles of ethyl esters of vegetable oil measured, nTAG the number of moles of triglycerides initially present in the oil, nDAG that of the diglycerides initially present in the oil, nMAG the number of moles of monoglycerides initially present in oil.

In this case, the yield thus measured is 18.23%.

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Example 2

This example differs from Example 1 only by the catalytic charge, 20% (ie a mass of catalyst of 0.8 g).

The yield measured by the protocol of Example 1 is then 29.43%.

Example 3

This example differs from Example 1 only by the initial addition of silica to the reaction medium. Sil% is the silica filler, that is to say the silica / vegetable oil mass ratio. In this case, a mass of silica of 0.8 g, ie a silica filler of 20%, is added to the reaction medium.

The yield measured by the protocol of Example 1 is 51.56%.

Example 4

In this example, the reaction medium from Example 2 is reused. This reaction medium is subjected, after the 72 hours of reaction have elapsed, to coarse filtering so as to remove the particles of catalyst in suspension. To the medium thus filtered are added:

a Cat% catalytic filler of 20% (ie in this case 0.8 g), a silica filler Sil% of 20% (ie in this case 0.8 g of silica).

The reaction is then restarted in the new reaction medium thus recharged, without further addition of ethanol. After an additional 24 hour reaction time, the protocol of Example 1 is repeated to measure the yield. This turns out to be 79.65%,

Example 5

In this example, to the recharged reaction medium of Example 4 is, after the additional reaction time of 24 hours, a further addition of ethanol according to a molar ratio HV: EtOH of 1: 0.3 (i.e., in l species, a volume of 80 μΙ). The reaction is then restarted for a period of 6 hours, at the end of which the yield is measured by the protocol described in Example 1. This yield turns out to be 85.09%.

In this example, the ethanol was thus added gradually in two successive stages each consisting of introducing a fraction of the stoichiometric proportion of ethanol necessary for the total consumption of the oil. More precisely, i

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IWPttCAIA Each step of adding ethanol consists of the species adding ethanol at a HV; EtOH molar ratio of 1: 0.3, for a total ratio of 1: 0.6.

Example 6

In this example, to the reaction medium resulting from the new 6-hour reaction of Example 6, a second addition of ethanol is carried out according to an HV: EtOH molar ratio of 1: 0.3, ie a volume of 80 μl. The reaction is then restarted for a period of 6 hours, at the end of which the yield is measured by the protocol described in Example 1. This yield is found to be 95.56%.

In this example, the ethanol was thus added gradually in three successive steps each consisting of introducing a fraction of the stoichiometric proportion of ethanol necessary for the total consumption of the oil. Specifically, each ethanol addition step in this case consists of adding ethanol at an HV: EtOH molar ratio of 1: 0.3, for a total ratio of 1: 0.9.

The examples presented above demonstrate the advantage of combining a gradual introduction of ethanol into the reaction medium with a silica filler in the presence of a plant enzyme as catalyst, in accordance with Examples 5 and 6.

The processes of Examples 1 to 4, provided for comparison, are not retained because of the low yields provided.

Examples 6 and 7 demonstrate a significant increase in yield when the gradual introduction of ethanol is combined with a silica filler.

Examples 5 and 6 compared with each other show that the yield increases when, in the presence of a silica filler, the final HV: EtOH molar ratio reaches 1: 4.5 by slow gradual addition of ethanol.

The process for the production of ethanolic esters according to Examples 5 or 6 above provides the following advantages.

First, it is possible to use hydrated ethanol up to 5% without noticeable impact on the yield. In addition, the alcohol / oil ratio is lower than in the majority of known transesterification reactions, which reduces the environmental impact.

Second, the side reactions of saponification of free fatty acids are avoided. In fact, there is an esterification

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OllPttCAÎ ^ ¹⁶⁸¹⁴ at least partial of the free fatty acids in ethyl esters, at least when the initial volume content of these free fatty acids in the reaction medium is less than 20%. As a corollary, it is thus possible to use a vegetable oil (or an animal fat), which significantly reduces the environmental impact and makes it possible to widen the range of raw materials used to carry out the transesterification reaction.

Third, the catalyst made from sprouted seeds of Jatropha Curcas is particularly effective, to the point that it is not necessary to combine it with a solvent in the reaction medium. In other words, the catalyst is used in the raw state, for the benefit of the ecological character of the process. In addition, this catalyst is particularly stable and can be recycled, which is also advantageous in terms of energy savings and environmental impact.

Fourth, silica, which performs an adsorption function for the glycerol produced during the reaction, makes it possible to reduce (or even eliminate) the inhibitory effect of glycerol on the catalytic activity of the plant enzyme (lipase).

Fifth, the esters can be extracted from the reaction medium without phase separation, thanks to the trapping of the glycerol in the silica. Consequently, the purification of the product obtained can be carried out by simple filtration of the reaction medium in order to extract therefrom the silica loaded with glycerol. This results in a reduction in the number of process steps, from the introduction of the alcohol to the extraction of the esters. Incidentally, the trapped glycerol turns out to be particularly pure (compared to the glycerol obtained by chemical catalysis processes, which requires post-treatment) and can be directly upgraded as a by-product of the reaction.

Sixth, the reaction can be carried out under mild conditions of temperature (below 45 ° C) and pressure (atmospheric), which saves energy and significantly reduces the environmental impact.

It will be noted that, although the reaction protocols proposed result from tests carried out on an experimental scale, no particular difficulty is opposed to their transposition to the industrial scale.

i

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On this occasion, the gradual addition of the ethanol to the reaction medium can be carried out in a fractional manner, that is to say that the ethanol is introduced in several successive point additions, or continuously, i.e. that is to say that the ethanol is introduced continuously at a low rate into the reaction medium until total consumption of the triglycerides.

The esters obtained can be used as biodiesels, but also as chemical intermediates, in particular in the field of the preparation of cosmetic products.

It will be noted that, although the process for the production of ethanolic esters described above makes it possible to obtain good results with a plant enzyme extracted from the germinated seed of Jatropha Curcas, it is possible to envisage using other plant enzymatic sources. , in particular oil plants or (possibly germinated) oil seeds, such as:

all types of Jatropha (in particular Jatropha mahafaliensis and Jatropha gossypiifolia) and more generally other members of the Euphorbiaceae family;

Shea butter (especially Vitellaria paradoxa) and more generally all members of the Sapotaceae family;

Moringa (typically Moringa oleifera, Moringa stenopetala), and more generally other members of the Moringaceae family,

Baobab (especially Adansonia), and more generally other members of the Bombacaceae family;

Fig / Prickly pear (Opuntia ficus-indica), and more generally other members of the Cactaceae family;

Marula or Sakoa (Sclerocarya bîrrea), and more generally the other members of the Anacardiaceae family;

Neem (Azadirachta indica), and more generally the other members of the Meliaceae family;

Date palm (Balanites aegyptiaca), and more generally other members of the Zygophyllaceae family.

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Claims (7)

1. Process for the production of ethanolic esters by transesterification of triglycerides from vegetable oil or animal fat with ethanol, depending on the reaction: triglycerides + ethanol -> ethanolic esters + glycerol this reaction being catalyzed by a plant enzyme, this process being characterized by: the gradual introduction of ethanol into the reaction medium; the introduction of silica into the reactive medium to effect adsorption of at least part of the glycerol produced. 2. Method according to claim 1, characterized in that the introduction of ethanol is carried out in at least two successive steps each consisting of introducing a fraction of the stoichiometric proportion of ethanol necessary for the total consumption of the oil. 3. Method according to claim 1 or claim 2, characterized in that the enzyme is derived from an oilseed plant or an oilseed. 4. Method according to claim 3, characterized in that the catalyst introduced into the reactive medium is in the form of a powder of sprouted seeds of Jatropha Curcas. 5. Process according to Moon of claims previous ones, characterized in that between 35 ° that the C and 40 ° reaction is vs. driving to a temperature 6. Process according to Moon of claims previous ones, characterized in that atmospheric. the reaction is driven pressure 7. Process according to Moon of claims previous ones, characterized in that the ethanol is introduced into the reaction medium in a molar ratio to oil or fat of between 1: 0.3 and 1: 0.9. 8. Method according to one of the preceding claims, characterized in that the catalyst is introduced into the reaction medium according to a catalyst / oil or fat mass ratio of between 10% and 20%. D019 B002 OA Version: TQD 9. Method according to one of the preceding claims, characterized in that the ethanol is partially hydrated, 10. The method of claim 9, characterized in that the ethanol has a water content of about 5%.