RO130749B1 - Basic heterogeneous catalyst for preparing methyl esters, process for preparing said catalyst and process for preparing fatty acid methyl esters - Google Patents

Abstract

The invention relates to a heterogeneous base catalyst and to a process for preparing fatty acid methyl esters by using said catalyst. According to the invention, the catalyst comprises sodium metasilicate, hydrotalcite with the Mg:Alatomic ratio of 2...3:1 and bentonite. According to the invention, the process consists in treating fats with methanol and a solid superacid catalyst, at the temperature of 66...70°C, wherefrom the filtrate is treated with the claimed heterogeneous base catalyst, at a temperature of 65...69°C, for 60...90 min, after which the catalyst is removed, the glycerine is separated from the fatty acid methyl esters which are further on treated with the previously separated base catalyst together with methanol, wherefrom methyl esters result and they are further filtered through an inorganic filtering layer.

Description

The invention relates to a process and a catalyst for obtaining methyl esters of fatty acids, by chemically processing fatty acids containing free fatty acids, for use as known biofuels and also known as biodiesel, biofuel intermediates. synthetic for aviation, intermediates for detergents, or environmentally friendly solvents.

Numerous processes are known for the production of alkyl esters of fatty acids, by transesterification of triglycerides from vegetable or animal fats, optionally by prior esterification of free fatty acids from their component with a lower alcohol, preferably methanol, in the presence of catalytic systems. homogeneous, acidic, alkaline, or heterogeneous.

It is known, from the patent RO 121913 B1, a diesel biofuel based on methyl esters of fatty acids, and a process for obtaining it by chemical processing of the vegetable oils in several stages.

Also known from US 8624073 (B1) is a process for producing biodiesel by transesterification, comprising: contacting an oil of plant or animal origin with an aliphatic monohydroxyl alcohol of 1 to 6 carbon atoms, and a homogeneous catalyst, to carry out the transesterification in order to obtain a mixture of alkyl esters of fatty acids and glycerin. The homogeneous catalyst is of the non-basic, non-acid type, being an organo-metallic compound of the formula: M (OCH3) x, wherein M is a metal selected from the group: B, Na, Mg, K, Ca, Se, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Al, Sn, Sb, Mo, Ag, Cd, and x is an integer, 2, 3 or 4. The process has some disadvantages related to the high cost price of the catalyst.

A single-phase liquid process for the esterification of a mixture of fatty acids and triglycerides, which comprises:

(a) making a solution of fatty acids, triglycerides, an alcohol, an acid catalyst of the sulfuric acid type and a cosolvent, at a temperature lower than the boiling point of the solution, said alcohol being selected from methanol, ethanol and mixtures of their ratio, and the molar ratio between alcohol and triglycerides, plus one third of the fatty acids being in the range of 15: 1 to 35: 1, the cosolvent being in an amount sufficient to form a single liquid phase;

(b) maintaining the solution for a period of time necessary for the acid catalyzed fatty acid esterification;

(c) neutralizing the acid catalyst and adding a basic catalyst, such as sodium or potassium hydroxide, for transesterification of triglycerides;

(d) after a period of time, the separation of the esters from the respective solution.

The process has disadvantages related to the need to neutralize the acid catalyst, the removal of the cosolvent by distillation, and the use of appreciable quantities of acidic water, for the purification of crude alkyl esters.

From the patent application WO 2014033760 (A1) a process for the preparation of a synthetic hydrotalcite is known, using three industrial residues, aluminum chloride waste, resulting from processes based on Freidel Craft reactions, magnesium waste from natural evaporation of waste water. sea or groundwater, and a solution of ammonium carbonate generated in the organic pigment industries. The process involves preparation of aluminum precursors, and removal of metal impurities present in aluminum hydroxide, preparation of magnesium precursors, mixing of precursors, hydrothermal treatment of the mixture, and addition of surface modification agents, followed by filtration and drying. Hydrotalcite can be used as: (i) antacid, (ii) halogen sequestrant, (iii) base catalyst, or as a carrier, (iv) adsorbent for waste water treatment, (v) stabilizer for polyvinyl chloride and (vi) agent flame retardant.

RO 130749 Β1

The process has some disadvantages related to the high temperature required for the process, which leads to high pressures and, implicitly, to significant production costs.

Also, from the patent application US 4698186 (A), a continuous process for the pre-esterification of a fat or oil is known, for the reduction of the free fatty acid content, prior to the transesterification process, which includes:

(a) passing a crude fat mixed with methanol in a methanol molar ratio to the fat free fatty acid content from about 10: 1 to 50: 1, at

55 ... 65 ° C, over a heterogeneous fixed bed of pre-esterification catalyst, of the type of a solid, anion-exchange acid resin, containing a polymer matrix with sulfonic acid groups, to pre-esterify fatty acids free, and reduce the fat acidity index below 1;

(b) separating the pre-esterified fat, and passing it into a vaporizer to remove water and excess methanol. The process recommends dilution of the initial fat, before pre-esterification with low fat free fatty acids or with fatty acid methyl esters. The process has some disadvantages related to the limitation of the initial fat free fatty acids content (acidity index of maximum 10).

The technical problem that the invention solves is the simplification and efficiency of the process, by producing and using heterogeneous catalysts that perform efficiently, at atmospheric pressure, making possible the use of fatty materials with high free fatty acids, of lower quality, or recovered from waste.

The process according to the invention removes the aforementioned disadvantages in that the fats, chosen from microalgal oil, rapeseed, camelina, soybean, sunflower, saffron, flax, hemp, cotton, peanuts, pumpkin, corn germs, coconut, palm, sap palm, castor, olives, microalgal oil, cocoa butter, pork lard, fish, fattening oil, bovine, sheep fat, as such or mixtures thereof, in their natural state (raw), purified or recovered from waste , in the first stage, it is treated with methanol in a proportion of 20 ... 58% by weight, and with a solid catalyst superacid fresh or recovered from the previous batches, of the type SO ₄ ² / SnO2, in proportion of 4. ..6% by weight to fat, at temperatures of 68 ± 2 ° C, the water resulting from the esterification reaction of fatty acids is separated from the methanol in a rectification column, being removed, and the methanol is recirculated, until nd the acidity index of the reaction mass drops below 2 mg KOH / g, then the superacid solid catalyst is removed by filtration, it can be reused, and the filtrate is treated in the next step with a heterogeneous basic catalyst, consisting of sodium metasilicate , hydrotalcite with the atomic ratio Mg ²⁺ / AI ³⁺ of 2: 1, having the formula [Mg ²⁺ 066AI ³⁺ 033 (OH) ₂ ] ° ³³⁺ (OH) 033 · m H2O, or hydrotalcite with the atomic ratio Mg ²⁺ / AI ³⁺ of 3: 1, having the formula [Mg ²⁺ 075AI ³⁺ o, 25 (OH) 2] ⁰ '25 ⁺ (ΟΗ) 025 · m H ₂ O, and bentonite, hydrotalcite being in proportion to 144 ... 150% by weight compared to sodium metasilicate and 38% bentonite to sodium metasilicate, the catalyst being reusable, the heterogeneous basic catalyst being obtained by a process by which metasilicate sodium pentahydrate is mixed (Na ₂ SiO ₃ · 5H ₂ O) with hydrotalcite cake with the atomic ratio Mg ²⁺ / AI ^{3+ of} 2: 1, having 53.6% su, or with cake of hydrotalcite with the atomic ratio Mg ²⁺ / AI ³⁺ of 3: 1, having 53.6% su, in proportion of 161% by weight compared to sodium metasilicate pentahydrate, with bentonite in proportion of 21.8% by weight of sodium metasilicate pentahydrate, and with water 75% by weight compared to sodium metasilicate pentahydrate, until it becomes an extruded paste, resulting in granules of about 2 mm in diameter, which is dried at 100 ° C in an oven with vacuum, the heterogeneous basic catalyst being used fresh or recovered from the previous batches, in a proportion of 4 ... 6% by weight compared to fat, at temperatures of 67 ± 2 ° C, for 60 ... 90 min, is removed the catalyst by filtration or centrifugation is separated

RO 130749 Β1 by decanting or centrifuging glycerine from fatty acid methyl esters, which is further treated with the heterogeneous basic catalyst, previously separated, at temperatures of 67 ± 2 ° C, for 60 ... 90 min, together with methanol taken. 20 ... 30% by weight compared to the methanol used initially; the catalyst is removed by filtration or centrifugation, the glycerin is separated by the fatty acid methyl esters, from which excess methanol is removed by first distillation at atmospheric pressure, and then in vacuo, and the methyl esters are filtered through an inorganic filter layer. , selected from bentonite, acid-treated bentonite, diatomite, siicagel, activated charcoal and siicagel, provided that, in the case of fats with an acidity index of less than 2 mg KOH / g and a water content of less than 0.1%, can give up the first stage, of esterification of free fatty acids with superacid solid catalyst.

The invention has the following advantages:

- it provides a sustainable process, by using cheap fats, which cannot be used in food, having a high content of free fatty acids, being of lower quality or recovered from waste;

- produces and uses heterogeneous catalysts in the process, which are easily removed by filtration, without requiring expensive operations to purify the fatty acids methyl esters;

- it ensures reduced consumption of raw materials, and the possibility of reusing catalysts and by-products, contributing to the reduction of manufacturing costs;

- ensures low energy consumption by conducting technological operations at relatively low temperatures;

- does not require costly investments, due to the process's management at atmospheric pressure.

Following are 9 examples of embodiments of the invention.

Example 1 In an installation consisting of a 4-necked flask, equipped with electrically operated stirring, thermometer, drip funnel, condenser and electrically heated water bath, 250 g Mg (NO ₃ ) ₂ · 6H ₂ O are introduced and 180.06 g AI (NO ₃ ) ₃ 9H ₂ Dissolved in 1170 g of distilled water. The Mg ²⁺ / AI ³⁺ atomic ratio is 2: 1. Over this solution the second solution formed by dissolving 88.66 g NaOH and 73.52 g Na2CO3 in 520 g water is dripped. The pH of the reaction mixture is maintained at 10 for 30 minutes. The resulting precipitate is aged at 60 ° C for 2 hours, then filtered, washed with deionized water, dried at 110 ° C and calcined at 500 ° C for 3 hours. The resulting product is suspended in distilled water, maintaining -is stirred for 3 hours, to restore the hydrotalcite structure. The slurry is filtered, resulting in 184 g hydrotalcite cake having 53.6% su and the formula [Mg ²⁺ 0, ₇₅ AI ³⁺ 0,25 (OH) 2] ° ²⁵⁺ (OH ') 0, ₂₅ · m H ₂ A.

184 g of hydrotalcite type Mg: AI = 2: 1 cake was introduced into a mixer, having 53.6% su, 114.3 g sodium metasilicate pentahydrate (Na ₂ SiO ₃ · 5H ₂ O), 86 g distilled water and 25 g bentonite. The mixture is homogenized until it becomes an extruded paste, resulting in granules of about 2 mm in diameter. The granules are dried in a vacuum oven at 100 ° C.

Example 2 In an installation consisting of a 4-necked flask, equipped with electrically operated stirring, thermometer, drip funnel, condenser and electrically heated water bath, 250 g Mg (NO ₃ ) ₂ · 6H ₂ O are introduced and 122.54 g AI (NO ₃ ) ₃ · 9H ₂ O, dissolved in 1170 g of distilled water. The Mg ²⁺ / AI ³⁺ atomic ratio is 3: 1. Over this solution the second solution formed by dissolving 88.66 g NaOH and 73.52 g Na2CO3 in 520 g water is dripped. The pH of the reaction mixture is maintained at 10 for 30 minutes. The resulting precipitate is aged at 60 ° C for 2 hours, then filtered, washed with deionized water, dried at 110 ° C and calcined at 500 ° C for 3 hours. The resulting product is suspended in distilled water, maintaining is stirred for 3 hours to restore the hydrotalcite structure. The slurry is filtered to give 170 g hydrotalcite cake having 51.5% su and the formula [Mg ²⁺ 0, ₇₅ AI ³⁺ 0.25 (OH) 2] ° ²⁵⁺ (OH ') 0, ₂₅ · m H ₂ A.

In a mixer 170 g of hydrotalcite type Mg: AI = 3: 1 cake is introduced into a mixer, having 51.5% su, 105.6 g metasilicate sodium pentahydrate (Na ₂ SiO ₃ · 5H ₂ O), 79 g distilled water and 23 g bentonite. The mixture is homogenized until it becomes an extruded paste, resulting in granules of about 2 mm in diameter. The granules are dried in a vacuum oven at 100 ° C.

Example 3 in an installation consisting of a 4-necked balloon, provided with electrically actuated shaking, thermometer and electrically heated oil bath, having the balloon assembled with a rectifier column with Sulzer-type structured filling, fed mid-water vapor -methanol resulting from the 4-necked flask, the column being coupled to the top with a reflux dispenser, a thermometer, a condenser and a methanol-collecting flask, and the lower part with an aqueous distilled collecting flask, inserted into the 4-necked flask 100 g microalgal oil, with saponification index 203.54 mg KOH / g, acidity index 87.54 mg KOH / g, and 0.12%) water. It is treated with 58 g methanol and 6 g super solid acid catalyst, of the type SO ₄ ² 7SnO ₂ . Stirring is started and the mixture in the flask is heated to 68 ± 2 ° C. Methanol vapors, with water resulting from the esterification reaction of free fatty acids, feed the rectification column. At the top of the column a methanolic fraction is separated, and at the lower one, an aqueous fraction. The reflux ratio is adjusted so that the temperature of the vapor at the top of the column is maintained at 65 ± 0.2 ° C. The methanol fraction is collected in a flask and is re-introduced into the 4-neck flask, and the aqueous fraction, separated in the lower flask, is removed. Stirring and heating are maintained for about 6 hours, until the aqueous fraction is no longer separated in the lower flask, and the acidity index of the reaction mass drops to 0.91 mg KOH / g. The super-acid catalyst is removed by filtration, to be used in subsequent batches, and the filtrate is transferred to an installation consisting of a 4-necked flask, provided with electrically operated stirring, thermometer, condenser and electrically heated oil bath. 5 g of the heterogeneous basic catalyst obtained according to Example 1 is introduced over the filtrate in the flask and the stirring and heating are started. The reaction mass was stirred at 67 ± 2 ° C for 60 minutes, then the catalyst was removed by filtration. 43.2 g of glycerin of 22.84% concentration is separated by decantation, from the methyl esters of crude fatty acids, which are reintroduced into the flask together with the previously catalyst separated by filtration, and with 11.6 g of methanol. The reaction mass was stirred at 67 ± 2 ° C for 60 minutes, then the catalyst was removed by filtration. 5.4 g crude glycerin of 17.6% concentration is separated by decantation from the crude fatty acid methyl esters, from which excess methanol is removed by first distillation at atmospheric pressure, and then in vacuo, then filtered through a acid treated bentonite filter layer. 93.9 g of fatty acid methyl esters are obtained, with the fatty acid composition according to Table 1, and the characteristics according to Table 2.

Example 4 in an installation consisting of a 4-necked balloon, provided with electrically operated stirring, thermometer and electrically heated oil bath, having the balloon assembled with a rectified column with structured filling, fed medially with the resulting water-methanol vapors from the 4-necked flask, the column being coupled at the top with a reflux dispenser, a thermometer, a condenser and a methanol-collecting flask, and at the bottom with an aqueous distilled collecting flask, is inserted into the 4-necked flask 100 g fat residual, recovered from the leather processing industry, with the saponification index 194.21 mg KOH / g, the acidity index of 9.32 mg KOH / g, and 0.15% water. This is treated with 44 g of methanol and 5 g of super acidic catalyst, of the SO ₄ ² 7SnO _{2 type} , recovered from batch 3. Start stirring and heat the mixture in the flask at 68 ± 2 ° C. Methanol vapors, with water resulting from the esterification reaction of free fatty acids, feed the rectification column. At the top of the column a methanolic fraction is separated, and at the lower one, an aqueous fraction. Adjust the reflux ratio

EN 130749 Β1 so that the temperature of the vapor at the top of the column is maintained at 65 ± 0.2 ° C. The methanol fraction is collected in a flask and is re-introduced into the 4-neck flask, and the aqueous fraction, separated in the lower flask, is removed. Stirring and heating are maintained for about 5 hours, until the aqueous fraction is no longer separated in the lower flask, and the acidity index of the reaction mass drops to 0.82 mg KOH / g. The super-acid catalyst is removed by filtration, to be used in subsequent batches, and the filtrate is transferred to an installation consisting of a 4-necked flask, provided with electrically operated stirring, thermometer, condenser and electrically heated oil bath. 6 g of heterogeneous basic catalyst, obtained according to example 2, is introduced over the filtrate in the flask and stirring and heating are started. The reaction mass is stirred at 67 ± 2 ° C for 50 minutes, then the catalyst is removed by filtration. Separate by 37.5 g of glycerin of 25.96% concentration, from the methyl esters of crude fatty acids, which are reintroduced in the flask together with the previously catalyst separated by filtration, and with 8.8 g of methanol. The reaction mass is stirred at 67 ± 2 ° C for 50 minutes, then the catalyst is removed by filtration. 3.4 g crude glycerin of 17.93% concentration is separated by decantation of the crude fatty acid methyl esters, from which excess methanol is removed by first distillation at atmospheric pressure, and then in vacuo, then filtered through a layer. diatomite filter. 94.4 g of fatty acid methyl esters are obtained, with the fatty acid composition according to Table 1, and the characteristics according to Table 2.

Example 5 in an installation consisting of a 4-necked balloon, provided with electrically actuated shaking, thermometer and electrically heated oil bath, having the balloon assembled with a Sulzer-type structured filling rectifier column fed mid-water vapor -methanol resulting from the 4-necked flask, the column being coupled to the top with a reflux dispenser, a thermometer, a condenser and a methanol-collecting flask, and the lower part, with an aqueous distilled flask, to the 4-flask 100 g residual oil collected from fast food units, with a saponification index of 191.43 mg KOH / g, an acidity index of 12.25 mg KOH / g, and 0.11% water, which is treats with 33 g methanol and 4 g solid acid catalyst, of the SO ₄ ² 7SnO _{2 type} . Stirring is started and the mixture in the flask is heated to 68 ± 2 ° C. Methanol vapors, with water resulting from the esterification reaction of free fatty acids, feed the rectification column. At the top of the column a methanolic fraction is separated, and at the lower one, an aqueous fraction. The reflux ratio is adjusted so that the temperature of the vapor at the top of the column is maintained at 65 ± 0.2 ° C. The methanol fraction is collected in a flask and is re-introduced into the 4-neck flask, and the aqueous fraction, separated in the lower flask, is removed. Stirring and heating are maintained for about 6 hours until the water no longer separates, and the acidity index drops to 0.85 mg KOH / g. The super-acid catalyst is removed by filtration, and the filtrate is transferred to an installation consisting of a 4-necked flask, equipped with electrically operated stirring, thermometer, condenser and electrically heated oil bath. 5 g of the heterogeneous basic catalyst, obtained according to example 2, is introduced over the filtrate in the flask and the agitation and heating are started. The reaction mass is stirred at 67 ± 2 ° C for 90 minutes, then the catalyst is removed by centrifugation. 24 g glycerin 38.71% concentration is separated by decantation, from the methyl esters of crude fatty acids, which are reintroduced into the flask together with the previously catalyst separated by filtration, and with 9.9 g methanol. The reaction mass is stirred at 67 ± 2 ° C for 90 minutes, then the catalyst is removed by filtration. 4.9 g crude glycerin of 23.14% concentration is separated by decantation from the crude fatty acid methyl esters, from which excess methanol is removed by first distillation at atmospheric pressure, and then in vacuo, and the esters are filtered through. a filter layer of activated carbon and silica gel. 94.7 g of fatty acid methyl esters are obtained, with the fatty acid composition according to Table 1, and the characteristics according to Table 2.

RO 130749 Β1

Example 6 In an installation consisting of a 4-necked flask, equipped with electrically operated shaking, thermometer, electrically heated oil bath and condenser, 100 g of camelina oil, with the saponification index 189.62 mg KOH / g is introduced. , the acidity index of 0.47 mg KOH / g, and 0.07% water, together with 22 g methanol recovered from the previous batches, and 4 g heterogeneous basic catalyst prepared according to Example 1, recovered from the previous batches. Shaking and heating are on. The reaction mass is stirred at 67 ± 2 ° C for 90 minutes, then the catalyst is removed by filtration. 17 g glycerin 54.13% is separated by decantation from the methyl esters of fatty acids, which are reintroduced into the flask together with the previously catalyst separated by filtration, and with 6.6 g methanol. The reaction mass is stirred at 67 ± 2 ° C for 90 minutes, then the catalyst is removed by filtration. Separate 5 g of glycerin of 17.81% concentration, from the methyl esters of crude fatty acids, from which excess methanol is removed by first distillation at atmospheric pressure, and then in vacuo, and the esters are filtered through a filtering layer. of bentonite. 95.3 g of fatty acid methyl esters are obtained, with the fatty acid composition according to Table 1, and the characteristics according to Table 2.

Example 7 In a plant consisting of a 4-necked flask, equipped with electrically operated shaking, thermometer, electrically heated oil bath and condenser, 100 g of palm oil is introduced, with the saponification index 201.44 mg KOH / g , the acidity index of 0.47 mg KOH / g, and 0.06% water, together with 20 g methanol and 4 g heterogeneous basic catalyst, prepared according to example 2, recovered from the previous batches. Shaking and heating are on. The reaction mass is stirred at 67 ± 2 ° C for 90 minutes, then the catalyst is removed by filtration. 16.4 g glycerin 59.95% is separated by decantation from the fatty acid methyl esters, which are reintroduced into the flask together with the previously separated catalyst by filtration, and with 6 g methanol. The reaction mass is stirred at 67 ± 2 ° C for 90 minutes, then the catalyst is removed by filtration. 5.4 g of 15.83% glycerin are separated by decantation from the crude fatty acid methyl esters, from which excess methanol is removed by first distillation at atmospheric pressure, and then in vacuo, and the esters are filtered through a Silica gel filter layer. 95.2 g of methyl esters of fatty acids are obtained, with the fatty acid composition according to Table 1, and the characteristics according to Table 2.

Example 8

Follow the procedure described in example 3, 4 or 5, replacing the microalgal oil, the residual fat recovered from the leather processing industry, or the residual oil, collected from fast food units, with rapeseed oil, soybeans, sunflower, camelina, saffron, in, hemp, cotton, peanuts, pumpkin, corn germs, coconut, palm, palm kernels, castor, olives, cocoa butter, pork lard, fish, squash fat, soy of bovine animals, sheep as such or mixtures thereof, in their natural state (raw), purified or recovered from waste, having an acidity index greater than 2 mg KOH / g. The yields and characteristics of the products thus obtained fall within the limits of the values presented in the examples above.

Example 9

Follow the procedure described in Example 6 or 7, replacing camel or palm oil with rapeseed oil, soybean, sunflower, saffron, flax, hemp, cotton, peanuts, pumpkin, corn germs, coconut, seeds palm, castor, olive, microalgal oil, cocoa butter, pork, fish, squash fat, bovine, sheep fat, as such or mixtures thereof, in their natural state (raw), purified or recovered from waste, having an acidity index of less than 2 mg KOH / g, and a water content of less than 0.1%. The yields and characteristics of the products thus obtained fall within the limits of the values presented in the examples above.

RO 130749 Β1

Table 1

The fatty acid composition of the fatty acid methyl esters

Nr. Components,% weight Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 1. Methyl octanoate, C8: 0 0 0.39 0 0 0 2. Methyl decanoate, CI0: 0 0 0.28 0.17 0 0 3. Methyl dodecanoate, Cl 2: 0 0 0.17 0.08 0 0.44 4. Methyl tetradecanoate, C14: 0 19.95 3.32 0.05 0 1.26 5. Methyl tetradecenoate, CI4: 1 3.70 0 0 0 0 6. Methyl hexadecanoate, CI6: 0 20.23 31.45 5.49 6.53 38.74 7. Methyl hexadecenoate, CI6: 1 32.67 3.42 0.10 0 0 8. Methyl hexadecadienoate, CI6: 2 4.64 0 0 0 0 9. Methyl hexadecatetraenoate, CI6: 4 1.57 0 0 0 0 10. Methyl octadecanoate, CI8: 0 0 20.14 4.98 2.93 4.74 11. Methyl octadecenoate, CI8: 1 4.30 37.77 31,32 18,20 43.49 12. Methyl octadecadienoate, CI8: 2 9.67 2.34 56.91 19.92 11.33 13. Methyl octadecatrienoate, CI8: 3 3.26 0.61 0.27 28:19 0 14. Methyl Icosanoate, C20: 0 0 0.11 0 2.09 0 15. Methyl icosaenoate, C20: l 0 0 0 15.47 0 16. Methyl Icosadienoate, C20: 2 0 0 0 1.69 0 17. Methyl Icosatrienoate, C20: 3 0 0 0 0.92 0 18. Methyl docosanoate, C22: 0 0 0 0 0.41 0 19. Methyl docosaenoate, C22: l 0 0 0.63 3.65 0

Table 2

Characteristics of methyl esters of fatty acids

Nr. Characteristics Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 1. Methyl ester content,% (g) 97.23 97.81 97.19 98.12 98.01 2. Density at 15 ° C, kg / mj 869 872 874 880 886 3. Acidity index, mg KOH / g 0.10 0.13 0.12 0.17 0.14 4. Water content,% (mg / kg) 89 97 74 110 93 5. Methanol content,% (g) 0.11 0.13 0.12 0.09 0.12 6. Monoglyceride content,% (g) 0.62 0.58 0.54 0.64 0.59 7. Diglyceride content,% (g) 0.17 0.15 0.12 0.13 0.19 8. Triglyceride content,% (g) 0.15 0.18 0.19 0.14 0.17 9. Free glycerin content,% (g) 0.016 0,018 0.013 0,015 0.017 10. Metal content (Na + K), mg / kg 2.56 3.14 2.94 3.01 2.87 11. Metal content (Ca + Mg), mg / kg 0.53 0.79 0.92 0.47 0.81

Claims (5)

claims 1. Heterogeneous basic catalyst, for the production of biodiesel, based on methyl esters 3 of fatty acids, characterized in that it consists of sodium metasilicate pentahydrate, hydrotalcite with an atomic ratio Mg ²⁺ / AI ³⁺ of 2: 1, having the formula [Mg ²⁺ 0 66AI ³⁺ 0 33 (O Η) ₂ ] ° ^'33+ (OH) _{0 33} m 5 H ₂ O, or hydrotalcite with the Mg ²⁺ / AI3 + atomic ratio of 3: 1, having the formula [Mg ²⁺ 0 75AI ³⁺ 0, ₂₅ (OH) ₂ ] ° ²⁵⁺ (OH) _{0 25} m H ₂ O and bentonite, the hydrotalcite being 144 ... 150% 7 by weight compared to sodium metasilicate and 38% bentonite compared to sodium metasilicate, the catalyst being reusable. 9 2. Process for obtaining the heterogeneous basic catalyst, characterized in that sodium metasilicate pentahydrate (Na ₂ SiO ₃ · 5H ₂ O) is mixed with the hydrotalcite cake with the atomic ratio Mg ²⁺ / AI ³⁺ of 2: 1, having 53.6% su, or hydrotalcite cake with the atomic ratio Mg ²⁺ / AI ³⁺ of 3: 1, having 53.6% su, in proportion of 161% by weight compared to the metasilicate 13 sodium pentahydrate, with bentonite 21.8% by weight compared to sodium metasilicate pentahydrate, and with water 75% by weight sodium metasilicate pentahydrate, 15 until it becomes an extruded paste, resulting in granules about 2 mm in diameter. , which is dried at 100 ° C in a vacuum oven. 17 3. A process for obtaining methyl esters of fatty acids, by chemically processing the fats containing free fatty acids, in several steps, using the heterogeneous basic catalyst 19 defined in claim 1, characterized in that, in the first step, the fats is treated with methanol in a proportion of 20 ... 58% by weight, and with a catalyst 21 solid superacid, fresh or recovered from the previous batches, of the type SO ₄ ² / SnO ₂ , in proportion of 4 ... 6% by weight, at 68 ± 2 ° C, the water resulting from the 23 fatty acid esterification reaction is separated from the methanol in a rectifying column, being removed, and the methanol is recirculated until the acidity index of the reaction mass drops below 25 mg 2 KOH / g, then the superacid solid catalyst is removed by filtration, which can be reused, and the filtrate is treated in the next step has a heterogeneous basic catalyst, 27 fresh or recovered from the previous batches, in a proportion of 4 ... 6% by weight compared to fat, at temperatures of 67 ± 2 ° C, for 60 ... 90 min, if Removes the catalyst by 29 filtration or centrifugation, separates by decanting or centrifuging glycerin from the fatty acid methyl esters, which are further treated with the heterogeneous base catalyst, previously 31 separated, at temperatures of 67 ± 2 ° C for 60. .90 min, together with methanol taken from 20 ... 30% by weight compared to the methanol initially used, the catalyst is removed by filtration 33 or centrifugation, the glycerine is separated by the fatty acid methyl esters, from which it is removed. the excess methanol by first distillation at atmospheric pressure, and then in vacuo, 35 and the methyl esters are filtered through an inorganic filter layer. 4. Process according to claim 3, characterized in that the fats are chosen 37 from the microalgal oil, rapeseed, camelina, soy, sunflower, saffron, flax, hemp, cotton, peanuts, pumpkin, corn germs, coconut, corn kernels palm, castor, olive, microalgal oil, 39 cocoa butter, pork lard, fish, fattening oil, bovine, sheep fat, as such or mixtures thereof, in their natural state (raw), purified or recovered from waste and 41 inorganic filter layer is selected from bentonite, acid treated bentonite, diatomite, silica gel, activated carbon. 43 5. Process according to claim 3, characterized in that, in the case of fats with an acidity index of less than 2 mg KOH / g and a water content of less than 0.1%, the first step of esterification of of free fatty acids with superacid solid catalyst.