FR2745296A1 - Transesterification of vegetable or animal oils - Google Patents

Abstract

Process for transesterification of a vegetable or animal oil using a solid heterogeneous catalyst comprising the stages of: (i) mixing a vegetable or animal oil with the required amount of a low alcohol, a fatty alcohol, a petrochemical alcohol (e.g. an oxo alcohol), a polyol or a carboxylic acid ester; (ii) maintaining the mixture under a protective atmosphere to avoid possible oxidation of ethylenic groups and to avoid possible oxidation of the glycerol produced; (iii) and maintaining the system at a temperature of >150 deg C, preferably 150-300 deg C in the presence of a solid heterogeneous catalyst based on Sn, Ge or Pb.

Description

TRANSESTERIFICATION METHOD
IN THE PRESENCE OF SOLID CATALYSTS
The invention relates to a process for the transesterification of vegetable and animal oils using a heterogeneous solid catalyst.

 The invention also relates to a solid catalyst based on a member selected from the group consisting of tin (Sn), germanium (Ge) and lead (Pb); the element chosen being preferably tin (Sn).

 The processes according to the invention are processes of an industrial nature whose main objective is the production of alkyl esters.

 The production of alkyl esters is of considerable interest since these compounds are used as a simple additive or as a synthetic intermediate in fields as diverse as the polymer, lubricant or cosmetics industry. These derivatives are prepared by transesterification or by esterification of carboxylic acids or their esters, raw materials of petrochemical or vegetable origin.

 In the present application, transesterification means: alcoholysis of an ester with an alcohol, or interesterification (exchange between two esters of alkoxy groups).

 Existing processes using the use of homogeneous catalysts of mineral origin such as acids (sulfuric acids, para-toluenesulphonic acids, etc.) and strong bases (sodium hydroxide, potassium hydroxide, sodium methoxide) are already known industrially. ...). The use of hetero-homogeneous systems such as potassium or sodium carbonates is also known. However, the soluble nature of the homogeneous catalysts entails major disadvantages such as the pollution by the catalytic system of the targeted products (dissolved salts), the non-recovery and the difficult recycling of these materials. These processes therefore have a harmful impact on the environment since the purification of the esters obtained involves the use and discharge of liquid effluents (solvents, acidic or basic wash waters).

 Therefore, these known methods are not always economical and pose a serious risk to the environment.

 WO 95/16014 teaches the use of combinations of alkaline oxides (CaO, BaO) and magnesium oxides for the transesterification of vegetable oils with light alcohols. The document EP 0 623 581 describes synthetic catalysts prepared by cation exchange and constituted by titanium-based silicalites used in the preparation of fatty acid and glycerol esters as well as in the transesterification of polyvinyl acetate by methanol.

 In the state of the prior art, it is known to use tin as a promoter of transesterification reactions, most often in the organometallic form (homogeneous systems based on alkyl or tin alkoxides) in the processes of polymerization for the synthesis of polyesters (Roelens, Perkin transactions, No. 8, pp 1617-1625, 1988), in the processes of transesterification of polyols (EP 0646 567) and alkoxy esters (WO 89 09762).

 EP 0 686 638 discloses tin-modified polymer resins used as a transesterification catalyst for methacrylate esters. However, these polymer resins have the disadvantage that the temperature of use of these materials obtained by polymerization of an aromatic alkyltin monomer, must not exceed 1500C.

 An object of the present invention is to overcome the disadvantages of the known art by proposing a transesterification process using a heterogeneous catalyst capable of withstanding temperatures above 1500C and having an industrial character.

In the present invention, the processed raw materials are generally raw materials and vegetable or animal oils (tallow). The claimed process relates to the transesterification of these raw materials in the presence of a light alcohol, a fatty alcohol, an alcohol derived from petrochemistry (eg oxo alcohol) or a polyol, or an ester d carboxylic acid (interesterification) and a solid material activated by tin according to a reaction of the following general type

<tb> vegetable oil <SEP><SEP> + <SEP> R3OH <SEP>-----><SEP> R1C02R3 <SEP> + <SEP> C3H803 <SEP> (glycerol)
<Tb>
In this reaction, R 1 and R 3 denote hydrocarbon radicals that may be saturated or unsaturated, linear or branched, or belong to the particular functionalized families, such as hydroxystearic or ricinoleic esters or alcohols.

 In this reaction, R 3 OH is an alcohol whose hydrocarbon chain is between 1 and 22 carbon atoms and more advantageously between 1 and 10 also comprising polyols such as glycerol, propylene glycol, ethylene glycol.

VEGETAL OILS
Vegetable oils can be refined or raw.

 By crude oil is meant a vegetable oil derived directly from the crushing (cold or hot pressure) of the oilseeds. The extracted liquid is simply filtered in order to remove the suspended solid particles which are most often seed residues (cake). However, in this crude oil are certain undesirable compounds such as water, partial glycerides, free fatty acids, phospholipids (phosphorus derivatives), waxes, sugars, etc.

The use of vegetable oil for food or industrial purposes therefore requires prior refining to remove these minor constituents (1 to 5% of the oil). This purification, generally delicate and expensive, involves various operations whose nature and number are strongly conditioned by the final destination of the oil treated (Manuel Corps Gras, A.

Karleskind, Lavoisier Editions, 1992, Volume II, chapter X, pp 789880). In the food sector, refining is extremely advanced and meets rigorous standards. For other industrial applications, it is usually called semi-refining since the number of steps is generally smaller. In this case, the main operations aim to rid the oil of its free acidity (neutralization), phospholipids (degumming), water and waxes (cold dewaxing).

 The alcoholysis of a vegetable oil proceeds in stages and passes through the diglyceride, then monoglyceride.

This reaction can therefore lead according to the reaction conditions (temperature, pressure, catalyst mass, amount of alcohol) to obtain esters of the corresponding alcohol, mono and diglycerides and glycerol.

PREPARATION OF CATALYSTS
The germanium or lead tin catalysts that can be used in the context of the present invention can be synthesized according to different preparative techniques.
a) impregnation of a solid support with metal salts based on tin, germanium or lead in solution,
b) so-called sol-gel polymerization method,
c) action of an organometallic tin germanium or lead on a support,
d) precipitation in acidic or basic medium salts of tin, germanium or lead.

 With regard to the impregnation method a), the support is brought into contact with an aqueous or organic solution of metal salts for several hours with removal of the solvent either by heating in a sand bath or by filtration. Another technique consists in precipitating the tin hydroxides in the basic medium in the presence of the support.

Whatever the type of impregnation chosen, the material obtained can be subjected to the unitary drying operations (under inert gas or in an oven) and activation by air, hydrogen or an inert gas and this to temperatures between 100 and 500 ° C.

With regard to the so-called sol-gel b) polymerization method, it leads in particular to solids of the type
Sn / alumina, Sn / silica-alumina, Sn / silica, Sn / zirconia. This preparative technique has been described by Mizukami et al (F. Mizukami, "Preparation of Catalysts IV", Elsevier Science Publishers, pp 45-54, 1988). By way of example, the Sn / alumina system is obtained from SnCl 2 in solution in methanol, hexylene glycol and aluminum isopropoxide.

 With regard to the action of an organometallic on a support c), the solids can be synthesized according to a protocol similar to that described by Basset et al (JM Basset, "Preparation of Catalysts V", Elsevier Science Publishers, pp 717-728, 1991) in the preparation of metal-tin bimetallic catalysts. Thus, the action of tetrabutyltin (eg SnBu4) in solution (organic solvent) on the support, leads after filtration to a solid that can be before reaction, dried and / or activated according to the recommendations previously set forth.

 In general, metal precursors based on tin, germanium or lead may be chlorides, sulphates, acetates, oxalates or organometallic compounds (eg SnBu4).

 In the same way, the recommended supports are generally chosen from the group of aluminas, silicas, silica-aluminas, clays, metal oxides of groups IIB (eg ZnO), IIA (eg MgO) and IVA (eg TiO2). , activated carbon and graphite.

TRANSESTERTEICATION REACTIONS
The transesterification reaction is carried out in an autoclave type reactor (batch mode) or a continuous fixed bed reactor.

When the process is of the semi-closed batch type and is carried out from methyl esters (ethyl or propyl), it is possible to extract and recover continuously the light alcohol produced by the reaction either by entrainment by a flow. of inert gas, either by successive degassing.

 More generally, the temperature of the reaction process is greater than 1500 ° C. and preferably between 150 and 300 ° C. In order to avoid any oxidation of the ethylenic bonds present in the various substrates or a possible degradation of the glycerol product, it is recommended to purge the installation and the reactants with an inert gas is to carry out the reaction under an inert gas stream or a partial vacuum, or to carry out the reaction under an inert gas pressure of between 1 and 100 bar.

 The subject of the invention is a process for the transesterification of a vegetable or animal oil using a heterogeneous solid catalyst comprising the steps of: mixing a vegetable or animal oil with a required quantity of a light alcohol, or an alcohol grease, or an alcohol derived from petrochemistry, or a polyol, or a carboxylic acid ester for maintaining the mixture under an atmosphere control capable of preventing any oxidation of the ethylenic bonds or a possible degradation glycerol product; at a high temperature, characterized in that the heterogeneous solid catalyst is a catalyst based on a member selected from the group consisting of tin, germanium or lead and in that the elevated temperature is greater than 1500C and between 1500C and 300 ° C.

According to other features of the invention
the vegetable oil is a crude oil, without any refining prior to the implementation of the process,
- vegetable oil is a semi-refined or refined oil,
the transesterification process is an alcoholysis process with methanol, methanol or an alcohol having a number of carbon atoms of less than or equal to 22, the alcohol possibly also being a polyol such as glycerol or ethylene glycol; , or an analogous alcohol.

 The invention also relates to a catalyst for the transesterification of vegetable or animal oils or carboxylic acid esters, characterized in that the catalyst used is a solid catalyst, supported and constituted at least by a member selected from the group consisting of by tin, germanium and lead.

According to other features of the invention
the element chosen is tin (Sn),
the support of the active phase is taken from the group consisting of natural or synthetic aluminas, silicas, silica-aluminas, zeolites and / or clays, active carbons, graphites and IIB, IIA group oxides; and IVA,
the catalyst is prepared
either: by a) impregnation of the support with the metal salts in solution,
either: by b) polymerization method, called sol-gel method,
either: by c) action of an organometallic on the support,
either: d) precipitation in an acidic or basic medium on the support,
the catalyst is activated before the transesterification reaction
either by: a) gaseous treatment in a controlled atmosphere,
or by: b) a pre-reduction of the metal salts supported by a solution of sodium borohydride, followed by drying of the material thus obtained.

 The invention will be better understood from the following description given by way of non-limiting example with reference to a first group of examples of implementation of the invention.

 In the description which follows and according to the state of the art, the term conversion of the reagent R at time t1 is understood to mean the quantity corresponding to the ratio of the difference between the weight percentages of R in the reaction medium at times t0 and tl. , and weight percentage of R at the beginning of the reaction (to).

at time tl, Conversion of R = 100 * (9; Rto -% Rut1) /% Rto
with Rto = 100%
In the examples cited, the transformation of the reagent is followed by HPLC, this technique allowing us to observe the almost complete transformation of the latter. Thus in all cases, the conversion of the oil is then considered almost equal to 100%, with an accuracy of 0.2%.

 The yield of compound A is the product of the conversion of the reagent and the mass fraction of compound A.

The mass fraction of A is the ratio of the mass of A to the total mass of all the products of the reaction, mainly consisting of esters, glycerol and partial glycerides. The masses in each of the products are determined after extraction and recovery of the various constituents of the reaction medium. The ester yield is then expressed as follows
Yield Ester (t) = Conversion x mass Ester / mass (Ester +
Glycerol + partial glycerides).

 These definitions are consistent with those used in the state of the art.

PREPARATION OF CATALYSTS
Catalyst A
Catalyst A is prepared by contacting an alumina with a solution of tin (II) chloride. This mixture, kept stirring for 13 hours, is then filtered through
Buchner, then dried in the oven. The solid obtained is then calcined in air at 450 ° C. in a fixed-bed glass reactor.

Catalyst B
Catalyst B is prepared according to the same protocol as catalyst A by substituting alumina with activated carbon.

In this case, the solid is activated under a nitrogen-air mixture at 450 ° C for 12 hours.

Catalyst C
Catalyst C is prepared by dry impregnation.

The zinc oxide is contacted with a solution of tin (II) chloride. The mixture, maintained with stirring is brought to 804C. After total evaporation of the solution, the same drying and calcination operations are carried out as for catalyst A.

TRANSESTERIFICATION OF VEGETABLE OIL
EXAMPLE 1 Methanolysis of a Semi-Refined Sunflower Oil in the Presence of Catalyst A.

 The reaction is carried out in an autoclave pressure reactor equipped with a pressure sensor which is itself connected to a recorder. The vegetable oil, the required amount of methanol (molar ratio of methanol / oil = 12) and 4 g of catalyst A are mixed inside the reactor. The stirring speed is between 500 rpm. and 2000 rpm. The pressurized nitrogen reactor is stirred for 5 minutes. After a first degassing, this operation is repeated 3 times while bringing the mixture to the temperature of 220 ° C. During the temperature rise, the pressure tends to increase to reach a maximum pressure of between 35 and 60 ° C. bar in the case of methanol The evolution of the pressure in methanol is recorded as a function of time, this reading giving kinetic information on the quantity of alcohol consumed by the reaction Regularly taken samples are analyzed by chromatography At the end of the reaction, the reactor is cooled to ambient temperature by a circulation of water in a coil provided for this purpose.

Table 1 of Example 1: Conversion and yields of the reaction carried out at a temperature of 220 ° C., and with a molar ratio of methanol / oil of 12 ° C.
Catalyst Converter Sn Teips Conversion Rdt Esters Rdt Glycerol + Nono
(t by weight) (h) (t) ethyl (t) and Di Glycerides (t)
Sn / Alurine 5 9 100 90.5 9.5
The Sn / alumina system makes it possible to achieve a high yield of methyl esters. By-products of the reaction are glycerol as well as non-transesterified mono and di glycerides. Purification of the ester and glycerol phases is relatively easy (successive stages of evaporation, decantation and crystallization) since they require no washing and no neutralization. Therefore, the quality of the esters and glycerol is at least equal to or even higher (glycerol free of water, absence of alkaline soaps) than that observed in the prior art.

Table 2 of Example 1: Distribution and Conformation of Fatty Acids in the Starting Oil and in the Methyl Esters
Oil Ethyl Esters
Division
Acids 6ras (b)
C18: 65.5 65.6
C18: 1 24.2 24.5
C18: 0 4.0 4.1
C16: fl, C22: D 6.3 5.8
z Trans Isomer 0.0 0.0
The analysis by gas chromatography of the methyl esters obtained does not indicate any transisomerization or isomerization of position. The content of tin quantified by plasma emission spectrometry is below the detection threshold of the technique used (5 ppm).

EXAMPLE 2 Simultaneous Methanolysis and Partial Refining of a Raw Sunflower Oil in the Presence of Catalyst B
350 ml of crude sunflower oil and a required quantity of methanol corresponding to a molar ratio of methanol / oil = 12, and 4 g of catalyst B are introduced. The reaction is carried out for 9 hours under conditions identical to those described in US Pat. Example 1. At the end of the reaction, the mixture is cooled and the different phases are then separated to be analyzed.

Table 1 of Example 2: Conversion and Yields of the reaction carried out at a temperature of 220 ° C., and with a methanol / oil molar ratio of 12
Catalyst Converter Sn Jeeps Conversion Rdt Esters Yr Glycerol + Nono
(b by weight) (h) (t) ethyl (t) and di glycerides (t)
Sn / Coal
active 5 9 100 73.5 26.5
The results of Table 1 of Example 2 show that the Sn-supported systems are active in the direct transesterification of a crude oil, that is to say an oil without any prior refining.

 The yield of esters is substantially lower than that obtained from the refined oils and the initial presence of water, waxes and phospholipids alters the activity of the catalysts.

Table 2 of Example 2: Characteristics of the crude sunflower oil, the methyl esters and the glycerin obtained
Substrates Index Phosphorus content
of Acid (eg (ppi / g)
KOH / g)
Raw oil of Sunflower 3.5 70
(before reaction)
Eethyl esters 1.4 14
Glycerol 0.1 180
The acidity and phosphorus content in the ester phase (Table 2) indicate that the transesterification of a crude oil by heterogeneous catalysis, in the presence of tin catalysts, leads to methyl esters low in free fatty acids and in phosphorus. A significant portion of the phospholipids is removed during methanolysis and the glycerol phase captures some of the remaining phosphorus.

EXAMPLE 3 Transesterification of a Semi-refined Oleic Sunflower Oil (83% Oleic) with Butanol in the Presence of Catalyst C
A semi-refined sunflower oil (350 g), 264 g of butanol and 7 g of catalyst C are introduced. Under the same conditions as in Example 2 and after 9 hours of reaction, the reaction mixture is cooled at room temperature. ambient temperature. The excess butanol, the butyl esters, the glycerol and the partial glycerides are then separated.

Table 1 of Example 3: Conversion and Yields of the reaction carried out at a temperature of 220 ° C, and with a molar ratio of butanol / oil of 9
Catalyst Converter Sn Number Time Conversion Rdt Esters Yr Glycerol t Nono
(t by weight) (h) (z) butyl (t) and Di Glyceride (t)
Sn / ZnO 5 9 100 85 15
EXAMPLE 4 Transesterification of a Semi-refined Oleic Sunflower Oil (83% Oleic) with Glycerol in the Presence of Catalyst C
410 ml of semi-refined sunflower oil and a required amount of glycerol corresponding to a glycerol / oil molar ratio = 3, and 7 g of catalyst C are introduced. The reaction is carried out under conditions identical to those described in US Pat. Example 3 for 9 hours.

 At the end of the reaction, the mixture is cooled and then dissolved in hot methanol in order to extract the catalyst by filtration. The methanol is then distilled under vacuum. The mixture then obtained is finally analyzed by gas chromatography. The overall yield of mono glycerides is 63%.

Table 1 of Example 4: Conversion and yields (excluding glycerol) of the reaction carried out at a temperature of 220 ° C., and with a molar ratio of glycerol / oil of 3
Catalyst C Tin content Teips (h) Conversion Rdt Nono
(t by weight) (t) Glycerides (t)
Sn / ZnO 5 9 98 63
The industrial character and utility of the invention will become apparent to those skilled in the art through the detailed laboratory tests described below.
LABORATORY I TEST IN METHANOLYSIS OF AN OIL
SEMI-REFINED LINOLEIC SUNFLOWER IN THE PRESENCE OF A CATALYST
SN / ALUMINA
The term "semi-refined oil" means an oil which has undergone conventional neutralization treatments (removal of residual acidity), degumming (removal of phospholipids) and cold dewaxing (removal of natural waxes).

Synthesis of catalyst type A: Sn 5% (by weight) / alumina
In a beaker of 500 cc are introduced 40 g of alumina previously sieved (particle size 50 <d <100 mm, surface area 200 m2 / g) in 150 cc of distilled water. To the stirred suspension is added a solution of 4.001 g of SnCl2.2H2O (Fluka product) in 30 cc of distilled water. The mixture is then stirred for 12 hours and then filtered through
Buchner. the solid obtained is then oven-dried at 100 ° C. for 4 hours and then calcined under air at 450 ° C. in a fixed-bed glass reactor for 12 hours (calcination conditions) 20 g of solid, air flow rate 10 l / h, temperature ramp 4 "C / min.

from 25 to 450 ° C).

Catalytic test
The reaction is carried out in a micropilot reactor under pressure of autoclave type (volume 1 liter) equipped with a pressure sensor itself connected to a recorder. Inside are mixed 332.5 g (350 cc) of linoleic sunflower oil, 183 g of methanol (Prolabo product) and 4 g of catalyst A. The molar ratio oil / methanol is 12. The speed stirring is set at 1500 rpm. The reactor is then pressurized with 10 bar of nitrogen, stirring for 5 minutes.

After performing a first degassing, this operation is repeated 3 times while bringing the mixture to the temperature of 220 ° C (last purge at around 60 ° C). During the temperature rise, the pressure tends to increase to reach a maximum pressure of 55 bar. We follow the evolution of the methanol pressure as a function of time, this result giving us kinetic information on the amount of alcohol consumed by the reaction. In addition, we take samples over time (once an hour) that are analyzed by liquid and gas chromatography. At the end of the reaction, the reactor is cooled to ambient temperature by a circulation of water in the coil provided for this purpose.

Chromatographic analyzes
a) liquid chromatography - light scattering detector (DDL): the Shimadzu LC-10AS type HPLC chain is equipped with a DDL detector and a C8 silica gel column (stationary phase). The mobile phase is a methanol-water mixture evolving from 93/7% by volume to 100/0 during the analysis.

The sample analyzed consists of 0.05 g of reaction mixture dissolved in 20 cc of methanol.

 These analyzes provide us with gualitative information on the evolution of the reaction (presence of glyceride oil and unprocessed reagents).

 b) Gas Chromatography (GPC): The quantification of the reaction products is carried out by GPC, using a Varian 3400 chromatograph equipped with a FID detector and a capillary column of JW DB 23 type. The samples are then dissolved in a solution of n-heptane containing an external standard (methyl nonadecanoate). This well-known concentration compound makes it possible by comparison to quantify the esters formed as well as any transisomeric and / or positional isomerizations.

 c) The acid number and the phosphorus content of the reaction products (esters and glycerol) are determined according to methods described by the French standards ISO 660-1983 and T 60-228 1969.

 d) The possible presence of acrolein resulting from the degradation of glycerol is detected by subjecting the ester and glycerol phases to the Schiff reagent (characteristic test for the presence of aldehydes). The validity of this test is of the order of ppm.

Extraction of the products of the reaction
At the end of the reaction, the reaction mixture is filtered on Buchner to remove the catalyst. The filtrate is then distilled under vacuum (70 ° C., 20 mm Hg) on a rotary evaporator in order to drive off the excess methanol.The reaction mixture is then centrifuged (20 minutes at 1500 rpm) in order to break the reaction. The ester-glycerol emulsion is then allowed to settle for 12 hours in an ampoule, the ester and glycerol phases are then separated and the esters are stored in the refrigerator for 12 hours at 6 ° C. The partial glycerides (mono and di) crystallized are separated from the thus purified ester phase by filtration and spin on
Buchner.

Results
Table 1 of Test I: Evolution of total methanol pressure over time
Teips (h) 0 (1) 1.5 4 5 6 8.6
Pressure (bar) 55 44 37 36 35 34
(1) time - O, when the temperature reaches the set point of 220 C Table 2 of the Test. Extraction and Analysis of Ester Phases, Glycerol and Partial Glycerides.

(g) Esters Glycerol Nono and Total Diasse
glycerides
Theoretical (1) 332 34 - 366
Obtained 285 11 19 345 (2)
(1) calculated for a conversion rate of 100
<RTI
When glycerol present in the form of mono and diglycerides is taken into account, the corrected glycerol yield is only 47% (it is assumed in this calculation that the partial glycerides are composed of 100% of monoglyceride). Consequently, the loss of product is segregative in the sense that the loss of glycerol is greater compared to that linked to the esters. As the Schiff reagent test proves to be negative, a degradation of the glycerol during the reaction can be excluded (Table 3). The difficult recovery of glycerol, a dense and viscous liquid, therefore appears to be at the origin of the losses observed.

 Finally, a plasma emission spectrometry assay detects no presence of tin in the methyl esters formed. The detection limit of this technique is 5 ppm.

LABORATORY II TEST OF METHANOLYSIS OF AN OIL
BRONZE OF LINOLEIC SUNFLOWER IN THE PRESENCE OF A CATALYST
SN / ACTIVE CHARCOAL
Synthesis of catalyst type B: Sn 5% (by weight) / activated carbon
Catalyst B is synthesized according to a protocol similar to that of its previous homologue A. The activated carbon has a specific surface area of 1200 m 2 / g. The activation mode of the catalyst consists of a calcination at 450 ° C. (12 hours), under a gas flow of 10 l / h and consisting of an air / nitrogen mixture (10/90 volume) in order to avoid combustion. carbon support.

 In this example, the oil to be transesterified is the crude product resulting from the direct trituration of the sunflower seed which has undergone prior reaction a filtration in order to remove the solid particles in suspension. It therefore has residual acidity, natural waxes, water and a high level of phospholipids.

 Table 1 of Test II: Extraction and analysis of ester, glycerol and partial glyceride phases.

(g) Esters Glycerol Nono and Di Nasse total
glycerides
Theoretical (1) 332 34 - 366
Obtained 249.5 18.5 71 339
(1) calculated for a conversion rate of 100 z
Table 2 of Trial II: Material balance and yields
Products Esters Glycerol nono and Di
glycerides
Overall Co-position 73.5 5.5 21
(t) tl)
Coeposition out 78 - 22
Glycerol (%)
Yield 75 54.5
Mass (t) (2)
Reactive NNN Test
Schiff (3)
(1) Composition of the mixture excluding methanol
(2) Ratio of the mass obtained and the theoretical mass (conversion - 100 3)
(3) Negative number
The loss of material associated with the purification operations of the different phases amounts to 7%. Overall losses in products are therefore relatively low.

 During this test the yield of methyl esters remains high (t 75% after extraction), and we do not detect acrolein in the reaction products despite an alteration of the catalyst activity due to the presence of conjugated phospholipids, water and waxes.

Table 3 of Test II: Acidity and phosphorus levels in the ester and glycerol phases obtained
Substrates Acid Number (.9 KOH / g) Phosphorus Content (pp / g)
Starting oil 3.5 70
Esters 1.4 14
Glycerol 0.1 180
The results shown in Table 3 clearly show that the residual acidity initially present in the oil is almost eliminated. This result implies that the Sn-supported system has esterifying properties. Moreover, during the filtration of the reaction mixture at the end of the reaction, part of the phospholipids is removed in solid form. Also the phosphorus content in the esters is relatively low. On the other hand, glycerol still remains rich in this element.

 In conclusion of the detailed tests I to II of implementation of the invention, during all these experiments, the fatty acid distribution of the esters formed is identical to that of the starting oil and the products of the reaction do not undergo any transisomerization or isomerization of position.

These observations are made from GPC analyzes of the starting substrates and the esters formed.

TEST III ALCOHOLIC LABORATORY BY BUTANOL
SEMI-REFINED OLEIC SUNFLOWER OIL IN THE PRESENCE OF A
CATALYST SN / ZNO
Synthesis of Catalyst C: Sn 5% (by weight) / Zinc oxide
In a beaker of 500 cc are introduced 20 g of zinc oxide (specific surface 10 m 2 / g) in 100 cc of distilled water. To the stirred suspension is added a solution consisting of 2.000 g of SnCl 2, 2H 2 O (Fluka product) in 30 cc of distilled water. The mixture is then stirred for 12 hours and then filtered on Buchner. The solid obtained is then dried in an oven at 100 ° C. for 4 hours and then calcined under air at 450 ° C. in a fixed-bed glass reactor for 12 hours (calcination conditions: 20 g of solid, air flow rate). l / h, temperature ramp 4 C / min from 25 to 450 C).

 This conversion leads mainly to butyl oleate since the starting oil contains 83% of oleic fraction.

The procedure is identical to that previously described, the amounts of reagents being as follows:
oil mass = 350 g
butanol mass = 264 g
Alcohol / oil molar ratio = 9
catalyst mass = 7 g
Table I of Test III: Evolution of total butanol pressure over time
Time (h) 0 (1) 1 2 3 4 5 9
Pressure (bar) 23.8 21.2 18.9 18.6 18.7 18.7 18.7 (1) time - O, when the temperature reaches the setpoint of 220 C
Table 2 of Test III: Extraction and Analysis of the ester, glycerol and partial glyceride phases.

(g) Esters Glycerol Phono and Total Drain
glycerides
Theoretical (1) 401 36.4 - 437.4
Obtained 317.4 13 44.3 374.7
(t) calculated for a conversion rate of 100
The yield of glycerol remains low (Table 3), this result being explained by the difficulty of recovering this compound and by the glycerol present in the form of mono and glycerides (corrected yield taking into account partial glycerides = 67%). On the other hand, the yield of butyl esters remains high (79%) even after extraction (Table 3).

Table 3 of Trial III: Material balance and yields
Products Esters Glycerol Nono and Di
glycerides
Global Coiposition 85 3 12
(t) (1)
Coiposition off 87.5 - 12.5
Glycerol (t)
Yield 79 35.5
Mass (t) (2)
Reactive NNN Test
Schiff (3)
(1) Composition of butanol mixture
2) Ratio of the mass obtained and the theoretical mass (conversion - 100 3)
(3) N - negative
The invention described with reference to particular embodiments is in no way limited, but on the contrary covers any variant of the process using a solid catalyst based on a component selected from the group consisting of tin, germanium or lead and compatible with a high temperature greater than 150 ° C and preferably between 150 "C and 300 C.

Claims (10)

 1 - Transesterification process of a vegetable or animal oil using a heterogeneous solid catalyst comprising the steps of: mixing a vegetable or animal oil with a required quantity of a light alcohol, or a fatty alcohol, or an alcohol derived from petrochemistry, or a polyol, or a carboxylic acid ester; maintaining the mixture under an atmosphere control capable of preventing any oxidation of the ethylenic bonds or a possible degradation of the glycerol product maintaining a high temperature, characterized in that the heterogeneous solid catalyst is a catalyst based on an element selected from the group consisting of tin, germanium or lead and in that the elevated temperature is greater than 1500C and between 1500C and 3000C.  2 - Process according to claim 1 and characterized in that the vegetable oil is a crude oil, without any refining prior to the implementation of the process.  3 - Process according to claim 1 characterized in that the vegetable oil is a semi-refined or refined oil.  4 - Process according to claim 1 characterized in that the transesterification process is a method of alcoholysis with methanol, ethanol or an alcohol having a number of carbon atoms less than or equal to 22.  5 - Process according to claim 1 characterized in that the alcohol is a polyol.  6 - Catalyst for the transesterification of vegetable or animal oils or of carboxylic acid esters, characterized in that the catalyst used is a solid catalyst, supported and constituted at least by a member selected from the group consisting of tin, germanium and lead.  7 - Catalyst according to claim 6, characterized in that the element chosen is tin (Sn).  8 - Catalyst according to claim 6 or 7, characterized in that the support of the active phase is taken from the group consisting of aluminas, silicas, silica-aluminas, zeolites, and / or natural or synthetic clays, active carbons, graphites and oxides of groups IIB, IIA and IVA.  9 - Catalyst according to any one of Claims 6 to 8, characterized in that the catalyst is prepared  either: by a) impregnation of the support with the metal salts in solution,  either: by b) polymerization method, called sol-gel method,  either: by c) action of an organometallic on the support,  either: d) precipitation in an acidic or basic medium on the support.  10 - Catalyst according to any one of claims 6 to 9, activated before the transesterification reaction  either by: a) gaseous treatment in a controlled atmosphere,  or by: b) a pre-reduction of the metal salts supported by a solution of sodium borohydride, followed by drying of the material thus obtained.