METHOD FOR THE COPRODUCTION OF C10 TO C13 OLEFINS AND ESTERS FROM FATTY ACID METHYL ESTERS

Abstract

The present invention addresses to a process for producing olefins and esters in the C10 to C13 range from fatty acid esters through a catalytic hydrogenation reaction followed by cross-metathesis of the hydrogenated product with light olefins.

Claims

1. A process for the coproduction of olefins and C10 to C13 esters from methyl fatty acid esters, the process comprising: a) catalytically hydrogenating methyl fatty acid esters with di- and tri-unsaturated chains; b) lysing the carbonic chains of methyl esters of the hydrogenated mixture by the cross-metathesis reaction with olefins of carbonic chains in the range of C2 to C6; and c) separating esters and olefins from the C10 to C13 chain by fractional distillation.

2. The process of claim 1, wherein the methyl fatty acid ester is obtained from vegetable oils.

3. The process of claim 1, wherein the olefin metathesis catalyst has the following chemical structure: ##STR00001##

4. The process of claim 3, wherein the organic ligand R is selected from the following chemical structures: ##STR00002##

5. The process of to claim 1, wherein the olefin metathesis catalyst has the following structural formula: ##STR00003##

6. The process of claim 5, wherein R1 is ##STR00004## and R2 is hydrogen; or R1 is ##STR00005## and R2 is NHCO.sub.2.sup.iBu; or R1 is ##STR00006## and R2 is NHCO.sub.2.sup.iBu.

7. The process of to claim 1, wherein the olefin is selected from the group consisting of: ethylene, 1-propene, 2-propene, 1-butene, 2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 3-hexene and mixtures thereof.

8. The process of claim 1, wherein the olefin is 1 butene.

9. The process of claim 1, wherein catalytically hydrogenating methyl fatty acid esters is conducted in a reactor at pressures from 5 to 80 bar (0.5 to 8 MPa), with temperature in the range of 30 to 80? C., with stirring from 10 to 2,000 rpm, space velocity from 0.1 to 10 h.sup.?1 or stirring time between 0.01 and 24 h.

10. The process of claim 9, wherein catalytically hydrogenating methyl fatty acid esters is conducted in a reactor at a temperature of 50? C., with 500 rpm of stirring and 0.5 h of stirring time.

11. The process of claim 1, wherein wherein catalytically hydrogenating methyl fatty acid esters occurs in the presence of a hydrogenation catalyst composed of 0.05% m/m to 5.0% m/m metallic palladium and 0.01% m/m to 1% m/m metallic silver deposited on gamma-alumina.

12. The process of claim 11, wherein the hydrogenation catalyst comprises 0.1% m/m to 5% m/m of metallic palladium deposited on active carbon.

13. The process of claim 11, wherein the hydrogenation catalyst comprises 0.05% m/m at 5.0% m/m of metallic palladium deposited on gamma-alumina.

14. The process of claim 11, wherein hydrogenation catalyst comprises 0.1% m/m of doped metallic palladium with 0.01% m/m to 1% m/m of metallic silver deposited on gamma-alumina.

15. The process of claim 12, wherein the hydrogenation catalyst comprises 0.5% m/m of metallic palladium deposited on active carbon.

16. The process of claim 13, wherein the hydrogenation catalyst comprises 0.7% m/m of metallic palladium deposited on gamma-alumina.

17. The process of claim 1, wherein metathesis reaction of olefins is conducted in a reaction vessel under the following conditions: pressure between 0.1 and 50 bar (0.01 and 5 MPa), stirring of the reaction medium at 10 to 2000 rpm, temperature between ?5 and 120? C., stirring time between 0.01 and 24 h.

18. The process for the coproduction of olefins and C10 to C13 esters from methyl fatty acid esters according to claim 17, characterized in that the metathesis reaction of olefins can be conducted in organic solvent and with inert gas.

19. The process of claim 17, wherein metathesis reaction of olefins is conducted with the organic solvent toluene.

20. The process of claim 17, wherein the inert gas is nitrogen or argon with a purity greater than 99.9%.

21. The process of claim 17, wherein the metathesis reaction of olefins is conducted in a reaction vessel under the following preferred conditions: pressure at 5 bar (0.5 MPa), stirring of the reaction medium at 500 rpm, temperature at 50? C., stirring time 0.5 h.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be described in more detail below, with reference to the attached figures which, in a schematic way and not limiting the inventive scope, represent examples of the same. In the drawings, there are:

[0022] FIG. 1 shows the ruthenium (I)-based metathesis catalyst with the R ligand.

[0023] FIG. 2 shows the R ligand referring to the metathesis catalyst of FIG. 1, where R can be the chemical structure (II), which corresponds to the structure of the first-generation Grubbs catalysts (GI), or the chemical structure (III), which corresponds to the structure of second-generation Grubbs catalysts (GII).

[0024] FIG. 3 shows another catalyst for metathesis of olefins based on ruthenium (IV), where R1 and R2 are organic radicals. The radical R2 can be a hydrogen atom (H) or the organic radical NHCO.sub.2.sup.iBu (isobutyl formate).

[0025] FIG. 4 shows the organic radical R1 of the metathesis catalyst shown in FIG. 3. The radical R1 can assume two different chemical structures shown: V and VI. When the radical R1 corresponds to structure V, the catalyst is known as a second-generation Hoveyda-Grubbs catalyst (HGII), and when the radical R1 corresponds to structures VI and VII, the catalysts are known as second-generation Hoveyda-Grubbs analogue catalysts.

[0026] FIG. 5 shows the metathesis reaction with 1-butene (butenolysis) with FAMEs from hydrogen-treated soybean oil (BSPHPartially Hydrogenated Soybean Biodiesel) in the presence of the metathesis catalyst (1). FIG. 5 also shows the expected products without parallel isomerization occurring: 1-decene (2), methyl 12-dodecenoate (3), 3-dodecene (4), methyl 9-decenoate (5), 1-heptene (6), methyl 12-pentadecenoate (7), 3-nonene (8), and methyl 12-tridecenoate (9).

[0027] FIG. 6 shows the chromatographic profile obtained by the analysis by gas chromatography of the products obtained in the butenolysis reaction of FAME from hydrogenated soybean oil under conditions in which a significant isomerization occurs, and the products from the isomerization are highlighted with an outline. The peaks present in the chromatogram shown in FIG. 6 refer to the following chemical compounds: 1-heptene (6), toluene (10), octene (11), 3-nonene (8), 1-decene (2), 1-undecene (12), 3-dodecene (4), methyl nonenoate (13), tridecene (14), methyl 9-decenoate (5), methyl undecenoate (15), methyl dodecenoate (16), methyl tridecenoate (9), methyl tetradecenoate (17), methyl pentadecenoate (18), methyl palmitate (19), methyl stearate (20).

DETAILED DESCRIPTION OF THE INVENTION

[0028] Preliminarily, it is emphasized that the description that follows will start from preferred embodiments of the invention. As will be evident to any technician skilled on the subject, however, the invention is not limited to these particular embodiments, but only to the scope of protection defined in the claims.

[0029] This work enabled the development of a previous treatment of the load by hydrogenation under conditions, such that the hydrogenation of compounds with 2 or 3 CC double bonds is highly selective, resulting in compounds with a CC double bond without the isomerization of the double bonds CC occurs significantly. To reduce isomerization, in this invention, catalysts were chosen, as well as the reaction conditions such as temperature, pressure and amount of hydrogen. In addition, the treatment with hydrogen is sufficient for the alkenolysis of FAMEs to occur with high efficiency of the metathesis catalyst, without the need for additional treatments to abate relevant impurities.

[0030] The process of lysis (breaking) of carbon chains of fatty acid methyl esters (FAME) is carried out through metathesis with olefins of chains in the range of C2 to C6 (alkenolysis), where there is a previous treatment by catalytic hydrogenation of the methyl fatty acid esters. The hydrogenation process takes place selectively with di- and tri-unsaturated chains to produce a mixture of hydrogenated products with monounsaturated chains, and in which the migration from the original position of the double bonds in the carbon chain is less than 5%, which is obtained through the choice of catalysts and process conditions. The FAMEs used in this hydrogenation process followed by metathesis with olefins in the C2 to C6 range are preferably obtained from vegetable oils via transesterification with methanol. It will be apparent to experts that the process could be applied to fatty acid ethyl esters, or even fatty acid triglycerides.

[0031] The metathesis catalyst consists of ruthenium, whose chemical structures and radicals are shown in FIGS. 1 to 4. The carbon chain olefins in the range from C2 to C6 are: ethene, 1-propene, 2-propene, 1-butene, 2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 3-hexene or mixtures thereof, it being preferable to use 1-butene because it is easier to access and used exclusively for products in the range of interest when reacting with methyl oleate. The olefin content is less important than the existence of relevant impurities. Impurities such as: peroxides, sulfonated elements, and others can be harmful even at levels below 100 ppm (0.01%). The short chain olefin must have impurity contents less than 100 ppm, preferably less than 10 ppm.

[0032] The process is conducted in four main steps: [0033] a) catalytic hydrogenation of methyl fatty acid esters with di- and tri-unsaturated chains; [0034] b) the lysis (or breaking) of the carbonic chains of methyl esters of the hydrogenated mixture by the cross-metathesis reaction with olefins of carbonic chains in the range of C3 to C6; [0035] c) separation of esters and olefins from the C10 to C13 chain by fractional distillation.

[0036] The hydrogenation step is conducted in a batch reactor or, even, mixing reactor (CSTRContinuous Stirred Tank Reactor), at pressures from 5 to 80 bar (0.5 to 8 MPa), with a temperature in the range of 30 to 80? C., with stirring of 10 to 2,000 rpm (revolutions per minute), space velocities from 0.1 to 10 h.sup.?1 or stifling time between 0.01 and 24 h. This step is preferably carried out in a mixture-type reactor (CSTR), at a temperature of 50? C., with 500 rpm of stirring and 0.5 h of stifling time. Alternatively, a fixed bed reactor can be used in the same ranges of the mentioned variables.

[0037] Decreasing temperature tends to reduce isomerization. It will be evident to specialists that temperatures even lower than those reported can be used with benefits for selectivity, but at the expense of reaction speed. Hydrogen pressure appears to have little influence on isomerization for certain catalysts. Pressures from 15 bar (1.5 MPa) to 80 bar (8 MPa) can be used, but the reaction must be stopped when the gauge pressure indicates the consumption of the stoichiometric amount of hydrogen necessary to hydrogenate di- and tri-unsaturated FAMEs to monounsaturated FAMEs. In the experimental arrangement used, this amount is approximately 15 bar (1.5 MPa). It will be obvious to experts that lower hydrogen pressures could be used, provided the reactor is fed back with enough hydrogen to reach the stoichiometric value. Higher hydrogen pressures could also be used as long as there are safety conditions for doing so.

[0038] The metathesis reaction of olefins is conducted in a reaction vessel under the following conditions: pressure between 0.1 and 50 bar (0.01 and 5 MPa), stirring of the reaction medium at 10 to 2000 rpm, temperature between ?5 and 120? C., stirring time between 0.01 h and 24 h. This reaction is preferably carried out under the following conditions: pressure at 5 bar (0.5 MPa), stirring of the reaction medium at 500 rpm, temperature at 50? C., stirring time 0.5 h.

[0039] It is known that the first-generation Grubbs catalysts (GI?structure I, ligand II) have a much lower performance than the second-generation Grubbs (GIIstructure Iligand III) in the butenolysis of FAMEs and triglycerides. It is also known that the second-generation Hoveyda-Grubbs catalyst (HGIIstructure IVligand V) and its analogues (structure IVligand VI) have similar activity to the GII catalyst. Furthermore, it is known that several catalysts with structures similar to I and IV are active for this reaction. The metathesis catalysts used were selected among dozens of possibilities, just to demonstrate that with the hydrogenation treatment of FAMEs under the selected conditions, isomerization products of the double bond are not formed, and butenolysis can be performed with a higher number of rotations (TON) to 50 thousand for these catalysts. The TON number specifies the maximum use that can be made of a catalyst, for a given reaction in particular, under the conditions defined by a series of molecular reactions or reaction cycles, which occur in the active center of the catalyst until its activity drops. The use of similar catalysts is already known in the state of the art and would be obvious to specialists.

EXAMPLES

[0040] Below, so that the invention can be better understood, experiments are presented that illustrate the invention, without, however, being considered limiting.

Example 1: Selective Hydrogenation of Soybean FAME and Ethenolysis

[0041] The hydrogenation reactions were carried out in a stainless-steel autoclave. A mass of FAMEs containing 17.1 mmol of methyl linoleate (10.3 g of FAMEs) and a mass of catalyst containing 0.005 mmol of palladium were added to a glass beaker. The glass beaker was placed in a stainless-steel reactor, which was pressurized with hydrogen. Finally, the reactor was placed on a heating plate with magnetic stirring, previously heated to the reaction temperature, and the pressure drop was recorded over time through a pressure transducer coupled to a fieldlogger recorder. The products were analyzed by gas chromatography and gas chromatography coupled to mass spectrometry. To determine whether there was the migration of double bonds, the hydrogenation products were separated and subjected to ethenolysis (metathesis with ethene), using the first-generation Grubbs catalyst (GI), although this is much less active and stable than the GII and HGII. The use of second-generation Grubbs and Hoveyda-Grubbs catalysts leads to the isomerization concomitant with the ethenolysis. As the ethenolysis was used here only in the context of an analytical tool to detect isomerization during hydrogenation, the poor performance of the catalyst was not an impediment. Under the tested conditions of ethenolysis, it was determined that the isomerization of the double bond does not occur. Thus, if products only explainable by the isomerization of the double bond occur, this isomerization occurred in the hydrogenation step. The results are shown in Table 1. The low presence of C9, C11, C12 and C14 products, for example, in tests 7 and 8, indicates that an isomerization did not occur in the hydrogenation step. Corroborating the results of the analysis by ethenolysis, the analysis by gas chromatography was performed using a column and chromatographic conditions in which the positional and geometric double bond isomers are separated. This analysis was consistent with the results using the ethenolysis as an analytical tool; that is, the incidence of isomerization products was minimal.

Example 2: Butenolysis

[0042] Soybean FAME hydrogenated as described in example 1 was subjected to butenolysis, and hydrogenation was the only previous treatment after synthesis of the FAMEs. In a steel reactor containing a magnetic bar coated with PTFE, under an inert atmosphere, 20 mL of the selectively hydrogenated soybean FAME, the second-generation Grubbs catalyst (GII) were introduced in a molar ratio of 15.6 ppm in relation to the number of moles of CC double bonds. The reactor was closed and cooled to ?5? C. (268 K). Five grams of 1-butene (purity greater than 99%) were condensed in the reactor, which was closed and transferred to an aluminum block previously heated to 60? C. under magnetic stirring, where it remained for 60 minutes. The reactor was removed, cooled and excess pressure (if any) was released through a needle valve under exhaustion. An aliquot of the products was taken and analyzed by gas chromatography. The results are presented in Table 2, where the fraction of products containing the ester group is identified.

[0043] The metathesis with 1-butene (butenolysis) was performed with hydrogen-treated soybean FAMEs (BSPH). The expected products without parallel isomerization occurring are shown in FIG. 5.

[0044] FIG. 6 shows the chromatographic profile (gas chromatography) of the butenolysis products of hydrogenated soybean FAME under conditions in which a significant isomerization occurs and the products from isomerization are highlighted with an outline. The distribution of unsaturated esters, products of the butenolysis, are shown in Table 2. The presence of methyl undecenoate and methyl tetradecenoate indicates the occurrence of isomerization. Thus, the quantification of these products is a way to monitor the occurrence of the position isomerization and the smaller the sum value, the smaller the occurrence of isomerization. Selected examples of the distribution of products in the olefinic fraction are shown in Table 3.

[0045] The pretreatment by hydrogenation under the conditions described in Table 2 in the tests with the PdAg/Al.sub.2O.sub.3 catalyst at 30? C. at 15 and 80 bar (1.5 and 8 MPa) indicate low isomerization, either in the hydrogenation phase or in the butenolysis phase. Since the only treatment is hydrogenation, the GII and HGII catalysts reach rotation numbers (turnover numberTON) greater than 50,000, indicating that the pre-treatment with hydrogen is sufficient to obtain a high performance for the metathesis catalyst.

TABLE-US-00001 TABLE 1 Chromatographic analysis and ethenolysis of partially hydrogenated soybean FAMEs under different conditions. Hydrogenation P (bar) Retention time (min) Ethenolysis 1 bar = T 18. 2 . 31.6 2. 33.2 33.7 34.2 38. Conversion Distribution of products (%) Test Catalyst 0.1 MPa (? C.) C C C C C C C C C FAME (load) 14 0 2 0 0 0 1 Pd/C 15 13 22 20 31 3 8 0 3 41 2 82 5 2 2 2 Pd 1 80 1 11 21 2 14 0 0 48 1 5 3 5 34 1 Al O 3 Pd/Al O 1 0 12 16 40 2 3 4 1 0 35 32 16 14 23 7 4 Pd/Al O 1 50 4 2 27 2 5 Pd/Al O 1 30 12 11 17 42 2 15 0 1 49 1 57 3 5 34 1 6 Pd/Al O 1 20 12 11 1 42 2 15 0 0 47 1 3 4 35 1 7 Pd/Al O 0 13 12 10 41 16 0 7 47 0 67 1 3 2 0 8 Pd/Al O 80 30 13 12 9 45 1 19 2 0 1 0 2 1 3 33 0 Conditions: .sup.a Soy FAME Hydrogenation = Soy FAME (22.0 mL), 0.005 mmol Pd, 700 rpm. .sup.b Ethenolysis and partially hydrogenated soy FAME (10 mL), G-I (10.0 mg), toluene (4.5 mL), ethylene (4.0 bar (0.4 MPa)), 50? C., 4 h, 500 rpm. .sup.c Conversion, calculated by gas chromatography using the area of methyl palmitate as an internal standard. .sup.d Considering only products containing an ester function. .sup.e Initial pressure of 80 bar (8 MPa) and the reaction was stopped after consuming 16 bar (1.6 MPa) of H.sub.2. indicates data missing or illegible when filed

TABLE-US-00002 TABLE 2 Soybean FAME hydrogenation followed by butenolysis. Hydrogenation Butenolysis Distribution of butenolysis esters (%) Hydrogenation Condition Catalyst for conversion methyl methyl methyl methyl methy methyl Catalyst butenolysis (%) dodecenoate I1 + I2 1 P A 80? C. 1 bar Grubbs 20 15 22 22 12 10 27 2 P B 80? C. 1 bar (structure I 90 2 24 22 5 14 1 3 P C 80? C. 1 bar ligand II) 8 28 24 19 12 1 4 P D 30? C. bar 2 26 22 22 12 1 5 P E 30? C. bar 2 8 2 23 7 12 1 6 P F 30? C. bar 2 3 2 2 23 14 4 7 P G 30? C. 3 2 23 23 1 4 8 P H 30? C. 29 2 23 20 18 4 P I 0? C. 80 bar 81 3 4 25 21 4 14 8 10 P J 30? C. 80 bar 84 3 4 25 21 4 14 8 11 P K 0? C. 80 bar Hovey 82 29 24 2 7 1 12 12 P L 30? C. bar Grubbs 81 3 2 28 21 4 14 8 13 P M 30? C. 80 bar (structure IV, 7 3 2 22 24 2 1 4 ligand V) Notes: 1Products derived from isomerization: I1 + I2. 2Hydrogenation condition: 22 mL of soybean biodiesel; catalyst: mass equivalent to 0.01 mmol of Pd; reaction stopped after consumption of the stoichiometric amount of hydrogen. 3Butenolysis conditions: 20 ml of partially hydrogenated soybean biodiesel (BSPH), 5 g of butene, 60? C., 2 h, amount of catalyst: 15.6 ppm (relative to the number of double bonds in the used BSPH). 4vacuum distilled BSPH before the butenolysis reaction. indicates data missing or illegible when filed

TABLE-US-00003 TABLE 3 Selected examples of the distribution of products in the olefinic fraction for the hydrogenation of soybean FAME followed by butenolysis Distribution of the olefinic fraction (%) Test heptene octene nonene 1-decene undecene dodecene 4 13 7 15 35 11 20 6 15 2 13 42 2 27 9 15 2 13 40 4 26 Note: 1reaction conditions: same as in Table 2 present in notes 2 and 3.