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IMPROVED PROCESS FOR THE SELECTIVE HYDROGENATION OF VEGETABLE OILS

20170362537 · 2017-12-21

    Inventors

    Cpc classification

    International classification

    Abstract

    Process for the catalytic hydrogenation of vegetable oils wherein the oil is placed in contact with molecular hydrogen in the presence of a metal catalyst, and the process is performed in the absence of water or in the presence of a quantity of water equal to or less than 5:1 with respect to the weight of the metal catalyst and at a temperature equal to or less than 50° C.

    Claims

    1. A process for the catalytic hydrogenation of vegetable oils wherein the oil is placed in contact with molecular hydrogen in the presence of a metal catalyst, wherein said process is performed in the absence of water or in the presence of a quantity of water equal to or less than 5:1 with respect to the weight of the metal catalyst and at a temperature from 18 to 3° C.

    2. The process according to claim 1, wherein said metal catalyst is selected from nickel, platinum, palladium, osmium, iridium, copper, iron, rhodium, ruthenium, molybdenum, tungsten and mixtures thereof.

    3. The process according to claim 2, wherein said metal catalyst comprises metallic Palladium.

    4. A process according to claim 3, wherein the hydrogenation is performed in the presence of 20 mg/kg-500 mg/kg of metallic Palladium with respect to the vegetable oil.

    5. The process according to claim 3, wherein said metal catalyst comprises 0.1-5% by weight of metallic Palladium.

    6. The process according to claim 1, wherein said metal catalyst is supported.

    7. The process according to claim 6, wherein the support of said metal catalyst is selected from alumina, carbon, CeO.sub.2, ZrO.sub.2, CrO.sub.2, TiO.sub.2, MgO, silica, inorganic-organic sol-gel matrices, polycrystalline oxide substrates, amorphous carbon, zeolites, aluminosilicates, alkaline earth carbonates such as magnesium carbonate, calcium carbonate or barium carbonate, barium sulfate, montmorillonites, polymer matrices, ion-exchange resins, polyfunctional resins, ceramic supports or a mixture of two or more thereof.

    8. The process according to claim 7, wherein the catalyst comprises metallic Palladium supported on alumina or carbon.

    9. The process according to claim 1, wherein the said process is performed at a molecular Hydrogen pressure of from 1 to 15 bar.

    10. The process according to claim 9 wherein the molecular Hydrogen pressure is of below 5 bar.

    11. The process according to claim 1 performed in the presence of a organic solvent selected from hydrocarbons, esters, ketones, C3-C6 alcohols, and ethers.

    12. The process according to claim 11, wherein the weight ratio of organic solvent to vegetable oil is from 0.25:1 to 3:1.

    13. The process according to claim 12, wherein the weight ratio of organic solvent to vegetable oil is from 1:1 to 2:1.

    14. A process for the catalytic hydrogenation reaction of vegetable oils selected from sunflower oil, oils from Brassicaceae or Cardoon oils, the said hydrogenation reaction being performed using a metal catalyst and in the absence of water or in the presence of a quantity of water equal to or less than 5:1 with respect to the weight of the metal catalyst and at a temperature equal of 18 to3° C.

    15. An oxidative cleavage reaction process which comprises using an oil obtained from the process according to claim 1 as starting material.

    16. The process according to claim 4, wherein said metal catalyst comprises 0.1-5% by weight of metallic Palladium.

    17. The process according to claim 2, wherein the said process is performed at a molecular Hydrogen pressure of from 1 to 15 bar.

    18. The process according to claim 3, wherein the said process is performed at a molecular Hydrogen pressure of from 1 to 15 bar.

    19. The process according to claim 4, wherein the said process is performed at a molecular Hydrogen pressure of from 1 to 15 bar.

    20. The process according to claim 5, wherein the said process is performed at a molecular Hydrogen pressure of from 1 to 15 bar.

    Description

    EXAMPLES

    [0061] In the following examples the carboxylic acid composition of the oil was determined after transesterification of an oil sample (140 μl) in 140 μl of methanolic KOH (2N). The methyl esters of the carboxylic acids were extracted from the methanolic solutions in 3 ml of hexane and then analyzed in a gas chromatograph equipped with flame ionization detector (FID) and a capillary column SLB-IL111 100 m×0.25 mm×0.2 micron (SUPELCO) at a constant pressure of 275 kPa.

    [0062] Temperature programme of the oven: 100° C. (35 min)—2.5° C./min—140° C. (30 min)—5.0° C./min—260° C. (25 min) for a total time of 130 min.

    [0063] Temperature of the injector: 250° C.; split ratio=250:1; carrier gas: helium.

    [0064] The conversion of diunsaturated acids (C18: 2) was determined as follows:

    [00001] ( Σ .Math. .Math. starting .Math. .Math. C .Math. .Math. 18 .Math. : .Math. 2 - Σ .Math. .Math. final .Math. .Math. C .Math. .Math. 18 .Math. : .Math. 2 ) Σ .Math. .Math. starting .Math. .Math. C .Math. .Math. 18 .Math. : .Math. 2 ,

    [0065] where Σ starting C18: and Σ final C18:2 correspond to the sum of the % weight of the various isomers of the diunsaturated C18 acids relative to the total carboxylic acid composition, before and after the hydrogenation reaction, respectively.

    [0066] The selectivity with respect to the monounsaturated acids (C18:1) was determined as follows:

    [00002] ( Σ .Math. .Math. final .Math. .Math. C .Math. .Math. 18 .Math. : .Math. 1 - Σ .Math. .Math. starting .Math. .Math. C .Math. .Math. 18 .Math. : .Math. 1 ) ( Σ .Math. .Math. starting .Math. .Math. C .Math. .Math. 18 .Math. : .Math. 2 - Σ .Math. .Math. final .Math. .Math. C .Math. .Math. 18 .Math. : .Math. 2 )

    [0067] where final Σ C18:1 and Σ starting C18:1 correspond to the sum of the % weight of the various isomers of monounsaturated C18 acids relative to the total carboxylic acid composition, after and before the hydrogenation reaction, respectively, and Σ starting C18:2 and Σ final C18:2 correspond to the sum of the % weight of the various isomers of the diunsaturated C18 acids relative to the total carboxylic acid composition, before and after the hydrogenation reaction, respectively.

    [0068] The trans-isomerization degree of the monounsaturated acids formed by hydrogenation was determined as follows:

    [00003] Σ .Math. .Math. C .Math. .Math. 18 .Math. : .Math. 1 .Math. .Math. trans ( Σ .Math. .Math. final .Math. .Math. C .Math. .Math. 18 .Math. : .Math. 1 - Σ .Math. .Math. starting .Math. .Math. C .Math. .Math. 18 .Math. : .Math. 1 )

    [0069] where Σ C18:1 trans corresponds to the sum of the % by weight of the trans isomers of monounsaturated C18 acids relative to the total carboxylic acid composition after the hydrogenation reaction, and Σ final C18:1 and Σ starting C18:1 correspond to the sum of the % weight of the various isomers of monounsaturated C18 acids relative to the total carboxylic acid composition, after and before the hydrogenation reaction, respectively.

    Example 1 (Comparative)

    [0070] 500 g of sunflower oil containing 56% by weight of linoleic acid with respect to the total fatty acids content were hydrogenated in an autoclave fitted with a stirrer in the presence of 15.5 g of catalyst based on palladium supported on y-alumina (0.2% by weight of Pd—“G68G” produced by Sud Chemie) at a temperature of 118° C., maintaining a hydrogen pressure between 2 and 5 bar. The reaction was interrupted after 80 minutes. The conversion of linoleic acid, determined by gas chromatographic analysis, was 34.5%, with selectivity for mono-unsaturated acids of 28.9%.

    Example 2

    [0071] The hydrogenation reaction was carried out in a cylindrical reactor with 500 ml capacity, equipped with electromagnetic stirrer and thermometer and connected to a hydrogen cylinder by means of mass flow meter.

    [0072] The reactor was charged with 50 g of cardoon oil, 150 ml (96 g) of petroleum ether and 0.84 g of catalyst in powder form consisting of 0.3% Pd/Al.sub.2O.sub.3 (Johnson Matthey; initial water content of 4.2% by weight), previously dried in vacuo at 80° C. for 2 hours (final water content of 1.13% corresponding to a weight ratio H2O:Pd of 3.8:1).

    [0073] The reactor was connected to a pump in order to remove the air and then fed with a stream of H.sub.2 with a flowrate of 30 ml/minute.

    [0074] The reactor was stirred vigorously for 110 minutes at 700 rpm, while maintaining a temperature of 5-6° C. in a cryostat. By means of a reactor output counter the quantity of absorbed hydrogen was measured, the value being equal to 2.71.

    [0075] The catalyst was filtered and the organic solvent was evaporated in order to obtain the hydrogenated cardoon oil. The percentage weight composition of C18 carboxylic acids of the hydrogenated oil relative to the total carboxylic acid composition as measured by means of GC analysis after 110 minutes' reaction, relative to the composition of the cardoon starting oil, is shown in Table 1.

    [0076] The conversion of linoleic acid was equal to 85% and the selectivity with respect to the oleic acid was 90%. As can be easily calculated from the data in Table 1, the trans-isomerization degree of the monounsaturated C18 acids formed by hydrogenation is of merely 18.6%.

    TABLE-US-00001 TABLE 1 Carboxylic acid composition Cardoon oil Example 2 Example 3 Hydrogenation time — 110 mns 137 mns Hydrogenation Temperature — 5-6° C. 20° C. C 18:0  3.2 7.4  7.8 C 18:1 cis 25.6 63.3  64.5 C 18:1 trans — 8.6 13.5 C 18:2 59.4 8.9  2.55 C 18:3  0.2 — — Conversion C18:2 —   85% 95.7% Selectivity C18:1 — 91.7% 92.3% 9-cis C18:1/Σ C18:1 96.7% 62.0% 59.0% 12-cis C18:1/Σ C18:1 — 24.7% 22.7% trans-isomerization degree of — 18.6% 25.7% C18:1 formed

    Example 3

    [0077] The hydrogenation reaction was carried out in the same reactor as that used in Example 2 with 50 g of cardoon oil, 50 g of petroleum ether and 0.757 g of catalyst in powder form consisting of 0.33%/Al.sub.2O.sub.3 (Johnson Matthey; water content equal to 0.4% by weight), with a resultant H.sub.2O:Pd weight ratio of 1.2:1.

    [0078] The reactor was connected to a pump in order to remove the air and then fed with a stream of H.sub.2 with a flowrate of 30 ml/minute.

    [0079] The reactor was stirred vigorously for about 137 minutes at 700 rpm, while maintaining a temperature of 20° C. in a cryostat. By means of a reactor output counter the quantity of absorbed hydrogen was measured, the value being equal to 2.71.

    [0080] The catalyst was filtered and the organic solvent was evaporated in order to obtain the hydrogenated cardoon oil. The percentage composition by weight of C18 carboxylic acids of the hydrogenated oil is shown in Table 1.

    [0081] The conversion of linoleic acid in presence of a water/Pd ratio of 1.2:1 was more than 95% and the selectivity with respect to the oleic acid higher than 90%, maintaining a selectivity with respect to the cis isomers higher than 80%. As can be seen from Table 1, the trans-isomerization degree after the hydrogenation reaction performed at 20° C. is of 25.7%.