MXPA99008459A - Procedure for obtaining oxo-alcohol superior from olef mixtures - Google Patents

Abstract

The present invention relates to: A process for obtaining higher oxo-alcohols from mixtures of isomeric olefins with 5 to 24 carbon atoms, by hydroformylation in the presence of a catalyst, at elevated temperature and under high pressure, in which the hydroformylation is carried out in one step, the transformation of the olefins for one pass is limited to 40 to 90%, the reaction mixture, conveniently after separating the catalyst, is selectively hydrogenated, the hydrogenation mixture is separated by distillation and the olefin fraction is fed back to the hydroformylation

Description

PROCEDURE FOR OBTAINOXO-UPPER ALCOHOLS FROM OLEFIN MIXTURES The invention relates to a process for obtainhigher oxo-alcohols by hydroformylatolefin mixtures, which includes a selective hydrogenation of hydroformylation mixtures, as well as a feedback of the non-transformed olefins. As is known, higher alcohols, especially those with 6 to 25 carbon atoms, can be obtained by catalytic hydroformylation (or oxo-reaction) of the olefins with a less carbon atom and the subsequent catalytic hydrogenation of the reaction mixtures. which contain aldehyde or alcohol. They are mainly used as educts for the preparation of plasticizers or detergents. The type of catalyst system and the optimal reaction conditions for hydroformylation depend on the reactivity of the olefin used. The dependence of olefin reactivity on its structure is described, for example, in J. Falbe, New Syntheses with Carbon Monoxide, Sprr-Verlag, Berlin, Heidelberg, New York, 1980, page 95 et seq. The different reactivity especially of isomeric octenes is also known (B.L. Haymore, A. van Hasselt, R. Beck, Annals of the New York Acad. Sci., 415 (1983), pages 159-175).

The olefin technical mixtures that are used as educts for the oxo-synthesis, contain olefin isomers of the most diverse structures with different degrees of branch different position of the double bond in the molecule and, eventually, also different number of carbon atoms . The above is especially valid for olefin mixtures, which were obtained by di-, tri- or other oligomerizations of olefins with 2 to 5 carbon atoms or other easily accessible higher olefins, or, by co-oligomerization of the olefins cited. As examples of typical isomeric olefin mixtures which by rhodium catalyzed hydroformylation or, preferably, catalyzed by cobalt, can be converted to the correspondmixtures of aldehyde and alcohol, tri- and tetrapropenes, as well as di-, tri- and tetrabutenes The rate of the hydroformylation reaction increases with increasnumber of carbon atoms, as well as the degree of branch The reaction rate of linear olefins may be 5 to 10 times higher than that of the branched isomers. Also the position of the double bond in the olefin molecule affects the reactivity. The olefins with final double bond react clearly faster than the isomers with the double bond in the interior of the molecule. Due to the different reactivity of the olefin isomers, relatively long reaction times are required if it is desired to achieve the broadest possible conversion of the olefins. However, in this way the product yield is reduced due to undesired secondary and subsequent reactions. The same happens when you try to reduce the reaction times by higher reaction temperatures. Mainly due to the different reactivity of the isomers, it is difficult in the case of the hydroformylation of olefin mixtures to obtain high transformations and, simultaneously, high selectivities. An object of the invention is to provide a process for obtainhigher oxo-alcohols from the correspondolefin mixtures, which combines high transformations with high selectivities and, furthermore, is characterized by high space-time yields. In accordance with the forego the subject of the invention is a process for obtainhigher oxo-alcohols from mixtures of isomeric olefins with 5 to 24 carbon atoms, by hydroformylation in the presence of a catalyst, at elevated temperature and under high pressure , in which the hydroformylation is carried out in one step, the transformation of the olefins for one pass is limited to 40 to 90%, the reaction mixture (conveniently after removing the catalyst) is selectively hydrogenated, the hydrogenation mixture is distilled off and the olefin fraction is fed back to the hydroformylation. The process according to the invention can be carried out batchwise, however, continuous work is advantageous. The Figure shows the block diagram of an installation, in which the procedure can be carried out continuously. In the reactor 1, the mixture of olefin 2, the synthesis gas (carbon monoxide and hydrogen) 3, and the catalyst 4 are introduced. The hydroformylation mixture 5 is decompressed, the decompression gas 6 (synthesis gas not consumed ) is removed and the decompressed hydroformylation mixture is released from the catalyst 4 in the catalyst 7 separation, which, optionally after being supplemented with fresh catalyst, is fed back into the reactor 1. The hydroformylation mixture 8 free of catalyst is brought to the hydrogenation 9, in which the aldehydes, as well as the acetals of aldehydes, obtained as by-products, and the esters of the alcohols, especially their formates, are hydrogenated to the alcohols. In the distillation 11, from the hydrogenation mixture 10, the low-boiling substances 12, which consist mainly of untransformed isomeric olefins, are separated and taken together with fresh olefins 13, as a mixture of olefin 2 into reactor 1.

A part of the low-boiling substances can be removed from the olefin circulation as low boiling residual substances 14. The crude alcohol mixture 15 is transformed into pure alcohol in an additional distillation not shown. The educts for hydroformylation are mixtures of monoolefins with 5 to 24 carbon atoms and final or central CC double bond, such as 1- or 2-pentene, 2-methyl-1-butene, 1-, 2- or 3-hexen, the isomeric mixture of 5 carbon atoms (dipropene) which is produced in the dimerization of propene, 1-heptene, 2- or 3-methyl-1-hexene, 1-octene, the isomeric mixture of olefin with 9 atoms carbon (dibutene) which is produced in the dimerization of butenene, 1-nonene, 2-, 3- or 4-methyl-1-octene, the isomeric mixture of 9-carbon atoms (tripropene) which is produced in the trimerization of propene, 1-, 2- or 3-decene, 2-ethyl-1-octene, 1 -dodecene, the isomeric mixture of 12-carbon olefin (tetrapropene or tributene) which is produced in the tetramerization of propene or in the trimerization of butenene, 1-tetradecene, 1- or 2-hexadecene, mixtures of 16-carbon olefin (tetrabutene) which are produced in the tetramerization of butenene, as well as olefin mixtures with different numbers of carbon atoms ( preferably 2 to 4), obtained by co-oligomerization of olefins, optionally after distillative separation in fractions with identical or similar number of carbon atoms. Preferred educts are olefin mixtures with 8, 9, 12 or 16 carbon atoms. The invention is not found in the type or in the conditions of hydroformylation. Rather, the olefins are hydroformylated in a manner known per se. That is to say, one works with rhodium catalysts, or preferably cobalt catalysts, as well as with or without complex stabilizing additives, such as organic phosphines or phosphites. The temperatures and pressures, depending on the catalyst and the olefin mixture, can vary within wide limits. A description of the hydroformylation of olefins is found, for example, in J. Falbe, New Syntheses with Carbon Monoxide, Springer-Verlag, Heidelberg-New York, 1980, page 99 et seq., As well as in Kirk-Othmer, Encyclopedia of Chemical Technology, Volume 17, 4th edition, John Wiley & Sons, pages 902-919 (1996). An essential feature of the invention is that the degree of transformation for a pass at 40 to 90% is limited. Advantageously, the olefins are converted to 65 to 80%. Preferred educts are mixtures of olefins with 8, 9, 12 or 16 carbon atoms, which consist of a large number of different isomers. As stated above, straight chain olefins react best with final olefinic double bonds. The reaction capacity decreases the more, the more branched the molecule is and / or the further inside the molecule the double bond is found. The transformation delimitation according to the invention has the consequence that the olefins capable of reacting, preferably react; those less able to react, remain in the reaction mixture and, after the selective hydrogenation thereof, are fed back to the hydroformylation. By means of the delimitation of the transformation, the selectivity of the hydroformylation is increased. With the olefin feedback, the total residence time for the less reactive olefins is prolonged. As a result of the olefin feedback, higher total olefin transformations are achieved with less formation of side products and, thus, with higher aldehyde yield, and, after hydrogenation, with higher alcohol yields. In addition, the smaller amount of secondary products facilitates the processing of the reaction mixtures. In comparison with the one-step procedure without olefin refed, the process according to the invention, thanks to the selective hydrogenation and the olefin feedback, it increases the ptability of obtaining oxo-alcohols. The degree of transformation of the olefins is limited to the desired value, suitably modifying the reaction conditions of the hydrmylation. By choosing lower reaction temperatures and / or catalyst concentrations, as well as shorter reaction times, the olefin transformation can be reduced. The degree of transformation for one pass of the olefin 2 mixture (= mixture of fresh olefin 13 + low boiling point substances 12) is determined based on the amount and composition of the olefin 2 mixture as well as the amount and the composition of the low boiling point substances 12, plus the low boiling point substances 14. The degree of total transformation is determined based on the amount and composition of the fresh olefin mixture 13, as well as the of the amounts of olefin separated with the other low-boiling substances 14. For the determination of the olefin contents in the various flow rates, the analysis by gas chromatography can be used. Conveniently, the reaction mixtures of the hydrmylation are first freed from the catalyst, again in a manner known per se. If a cobalt catalyst was used, the above can be effected by pressure discharge, separation of the aqueous catalyst phase, oxidation of the cobalt carbonyl compounds remaining in the hydrmylation mixture, with air or oxygen and the washing of the cobalt catalyst. the cobalt compounds that are obtained with water or aqueous acid. The de-cobalt processes are well known, see for example, J. Falbe, cited above, 164-165 (BASF-Process), Kirk-Othmer, cited above, as well as European Patent EP-0 850 905 Al. Si as a catalyst of hydrmylation a rhodium compound was used, it can be separated as a distillation residue from the hydrmylation mixture by thin layer evaporation. The reaction mixtures of the hydrmylation, released from the catalyst, according to the degree of conversion, generally contain 3-40% by weight, usually 5 to 30% by weight, of easily boiled substances with a lower boiling point than the aldehydes, especially olefins, furthermore the corresponding saturated hydrocarbons, as well as water and, optionally, methanol, likewise 30-90% by weight of aldehydes, 5-60% by weight of alcohols, up to 10% by weight of formates of these alcohols and 5-15% by weight of difficult boiling substances are higher boiling points than alcohols. However, it should be noted that the process according to the invention can also be carried out with hydrmylation mixtures, the composition of which does not agree with this data in this and / or that relation. The selective hydrogenation of the hydrmylation mixtures suitably released from the hydrmylation catalyst is another essential feature of the process according to the invention. In it, the aldehydes and certain accompanying substances, including acetals of the aldehydes as well as esters of the alcohols, and especially the formates of them, are hydrogenated to the desired alcohols. Since the transformation in the hydrmylation stage is defined, it is decisive for the ptability of the process that in the hydrogenation, the non-transformed olefins are not or practically not hydrogenated, so that they can be separated from the hydrogenation mixture and fed back to the hydrmylation. A selective hydrogenation of the hydrmylation mixtures is the object of Patent Application 198 42 370.5 (O.Z. 5356), currently pending. Accordingly, the reaction mixtures of the hydrmylation are hydrogenated by water at elevated temperature and under high pressure, in a carrier catalyst, which contains copper, nickel and chromium as active components. Preferred catalysts of this type are carrier catalysts which, as active components, contain copper and nickel in concentrations of respectively 0.3 to 15% by weight, chromium in a concentration of 0.05 to 3.5% by weight, as well as an alkali metal component in a concentration from 0.01 to 1.6% by weight, advantageously 0.02-1.2% by weight, respectively based on the carrier catalyst. Another advantageous carrier catalyst contains copper, nickel and chromium in the indicated amounts, but no alkali metal component. Suitable carrier substances are, in particular, silicon dioxide and aluminum oxide. The quantities indications refer to the catalyst obtained as described below, not yet reduced. In the hydrogenation, the aldehydes in the hydroformylation mixtures, with transformations of more than 98% at a selectivity of more than 99%, are hydrogenated in only one hydrogenation step to obtain the corresponding alcohols. The esters and the acetals are also transformed into the desired alcohols. Surprisingly, the starting olefins contained in the mixture remain in general unprocessed, although precisely the preferred carrier catalysts, under comparable conditions, also virtually quantitatively hydrogenate the double olefinic bond in 2-ethylhex-2-enal ( EP 0 326 674 A2). The hydrogenation can be carried out in the low pressure range of less than 30 bar 'and with high space-time yields. The catalytic components mentioned can be homogeneously distributed in the pores of a carrier material or enriched in their edge regions. In the first case, an aqueous solution is prepared, which contains as components of the catalyst the components in the form of metal salts and its volume is conveniently about 0.8 times the volume of the pores of the carrier material. As salts of copper, nickel and chromium, those which, when heated, are transformed into oxides, such as nitrates and acetates, are advantageously used. If the catalyst is to contain an alkali metal component, it can be introduced together with chromium in the form of an alkanichromate or an alkalidichromate, especially chromate or sodium dichromate. The concentration of the metal salts in the solution depends on the desired concentration of the respective component in the finished catalyst. The metal salt solution is then sprayed onto the previously unheated carrier material, which is in a dripping drum, and penetrates its pores. Subsequently, the catalyst is dried. If a catalyst with components that are enriched in the edge regions of a porous carrier material or more or less free of pores is desired, then the metal salt solution can be sprayed onto a preheated carrier material and continue to be heated during the spraying, so that the water evaporates and the catalytic components are fixed essentially on the surface of the carrier material. After applying the catalytic components, the catalysts of both types are calcined, ie, according to the catalyst precursor used, they are heated to temperatures of 200 to 400 ° C, the catalyst precursors being transformed into the oxides. Subsequently, the catalyst is reduced with hydrogen. The reduction can be carried out immediately after obtaining the catalyst or, conveniently, only in the hydrogenation reactor. Advantageously, the catalysts are used in a form in which they offer a lower resistance to flow, for example, in the form of granules, pellets or shaped bodies, such as tablets, cylinders, bar extrudates or rings. Conveniently, they are activated prior to their use by heating in hydrogen flow, for example, at the stated hydrogenation temperatures of 150 to 250 ° C, if they were not reduced in the reactor. The hydrogenation can be carried out continuously or discontinuously and both in the gas phase and also in the liquid phase. Hydrogenation is preferred in the liquid phase, since the gas phase process, due to the necessary circulation of large volumes of gas, requires more energy. To this it is added that the evaporation of the aldehydes, given an increasing number of carbon atoms, requires more and more energy and, in addition, the loading of educts in the reaction gas decreases, so that a gas phase process in the case of aldehydes with a carbon number greater than about 8, it makes the total process economically almost impossible.

For the hydrogenation of the liquid phase, various variants of the process can be selected. It can be carried out adiabatically or practically isothermally, that is, with an increase in temperature of < 10 ° C, in one or two stages. In the latter case, the two reactors, conveniently tube reactors, can operate in an adiabatic or practically isothermal manner. Likewise, it is possible to hydrogenate the hydroformylation mixtures in straight pass or with product feedback. The reactors can operate as direct current reactors with a trickle flow or, preferably, with high liquid loads (pulse flow). In the interest of a high space-time yield, the reactors operate preferably with high liquid loads of 5-100 m3, especially of 15-50 m3 per m2 of cross section of the empty reactor and hour. If a reactor operates in an isothermal manner and with a straight pass, the specific catalyst load (LHSV) can adopt values between 0.1 and 10 h "1, preferably between 0.5 and 5 hf 1. The liquid phase hydrogenation is carried out in In general, under a total pressure of 5 to 30 bar, especially between 15 and 25 bar, hydrogenation in the gas phase can also be carried out at lower pressures, with correspondingly large gas volumes. in the case of hydrogenation in the liquid or gaseous phase they are located between 120 and 220 ° C, especially between 140 and 180 ° C. After the hydrogenation, the reaction mixtures are processed in a manner known per se, by distillation. above is conveniently carried out under reduced pressure, for example, at an absolute pressure of 400 to 900 mbar, in which olefins are recovered as the predominant component of the fraction of readily boiling substances. The predominant part of the fraction of easily boiled substances, usually 60 to 98%, is fed back into the hydroformylation. The remaining portion of the fraction of easily boiled substances, ie 2 to 40%, can be locked out of the olefin circulation, so that the concentration of the inert saturated hydrocarbons that were formed in the hydroformylation stage by hydrogenation of olefins, do not exceed 70%, preferably, keep below 60%.

Comparative example Hydroformylation of di-n-butene In a high-pressure autoclave of 5 1, which was equipped with a stirrer and electric heating, 2000 g of di-n-butene were hydroformylated (olefin with 8 carbon atoms of the process). OXENO-octol), in the presence of a cobalt catalyst, at 180 ° C and constant pressure of the synthesis gas at 280 bar. The synthesis gas contained 50% by volume of CO and 50% by volume of H2. To obtain the cobalt hydrocarbons which act as a catalyst, an aqueous solution of cobalt acetate with 0.95% by weight of Co was used as a precursor. The cobalt acetate solution was treated for 7 h at 170 ° C and 280 bar with the synthesis gas with agitation. After cooling to room temperature and decompressing, the cobalt hydrocarbons which were formed were taken up with the di-n-butene of educt to the organic phase. After separating the aqueous phase, the di-n-butene charged with the cobalt hydrocarbons, containing 0.025% by weight of Co (calculated as metal), was hydroformylated for 3 hours under the aforesaid reaction conditions. After cooling to room temperature, the reaction mixture was decompressed, removed from the autoclave and, by treatment with 5% acetic acid and air, was released at 80 ° C from the cobalt catalyst. 2488 g of hydroformylation mixture were obtained, which were analyzed by gas chromatography (GC). The results are shown in Table 1. Subsequently a reaction of di-n-butene of 89.3% with a selectivity of valuable product of 90.7% was reached, which is equivalent to a yield of valuable product of 81.0%, referred to the di- n-butene employed. The aldehydes of 9 carbon atoms, the alcohols of 9 carbon atoms and the isononylformates are considered valuable products.

EXAMPLE (according to the invention) Hydroformylation of di-n-butene with 8-C-olefin refed 2488 g of the hydroformylation mixture of the comparative example were selectively hydrogenated while preserving the olefins, to obtain the valuable 9-atom alcohol product carbon. The hydrogenation was carried out batchwise in a 5 1 autoclave, at 180 ° C and 20 bar H2 pressure in the liquid phase, in the presence of a carrier catalyst with 12.1 wt% Cu, 3.0 wt% of Ni and 2.5% by weight of Cr in aluminum oxide as a carrier material. Then, in a laboratory distillation column, from the hydrogenation mixture, the olefins that did not react as low boiling substances and the high boiling substances were distilled from the valuable products. 250 g of a fraction of low-boiling substances were obtained, which, according to the gas chromatography analysis, in addition to 98.7% by weight of hydrocarbons of 8 carbon atoms, of which it was 78.4% by weight olefins of 8 atoms of carbon, contained about 1.3% by weight of methanol (sequential product of the hydrogenation of isononylformate).

The fraction of low boiling substances and 2000 g of di-n-butene, ie in total 2250 g of educt with 2193 g of olefin of 8 carbon atoms, were hydroformylated as in the comparative example, at 180 ° C in a 5 1 autoclave and a synthesis gas pressure of 280 bar, in the presence of a cobalt catalyst. A synthesis gas with 50% by volume of CO and 50% by volume of H2 was used again. With a cobalt content of 0.024% by weight of Co, based on the olefin mixture of 8 carbon atoms, this mixture was hydroformylated for 3 hours. After cooling to room temperature, the reaction mixture was decompressed, removed from the autoclave and, by treatment with 5% acetic acid and air at 80 ° C, was released from the Co catalyst. 2731 g of hydroformylation mixture were obtained, which were analyzed by gas chromatography. The results are indicated in Table 1. Subsequently, an 8-carbon olefin reaction of 88.2% was achieved with a 90.9% valuable product selectivity, which is equivalent to a yield of 80.2% valuable product, referred to the olefin of 8 carbon atoms used. Again, the aldehydes of 9 carbon atoms, the alcohols of 9 carbon atoms and the isononylformates are considered valuable products. In order to be able to evaluate the influence of the olefin feedback in accordance with the present invention on the performance of valuable products, the yield referred to the 8-carbon-olefin (di-n-butene and 8-carbon-olefin refed) became to the amount of fresh di-n-butene used (2000 g). According to said conversion, a yield of 88.0% based on di-n-butene results. With respect to the hydroformylation without olefin feedback according to the comparative example, with it an increase in the yields of valuable product of about 8% is obtained. In practice, the paraffins of 8 carbon atoms and a part of the olefins of 8 carbon atoms are blocked by a purge with the continuous process.

Table 1 Composition of hydroformylation mixtures In a one-stage process, therefore, the yield of valuable product can no longer be significantly improved by a higher di-n-butene reaction, since with the increase in reaction a decrease in selectivity occurs by sequential reactions. The process according to the invention, on the other hand, allows a greater di-n-butene reaction to obtain valuable products without reducing the selectivity.

Claims (18)

1. A process for obtaining higher oxo-alcohols from mixtures of isomeric olefins with 5 to 24 carbon atoms, by hydroformylation in the presence of a catalyst, at elevated temperature and under high pressure, characterized in that the hydroformylation is carried out in one step , the transformation of the olefins for one passage is limited to 40 to 90%, the reaction mixture, conveniently after separating the catalyst, is selectively hydrogenated, the hydrogenation mixture is distilled off and the olefin fraction is fed back to the hydroformylation.

2. A process according to claim 1, characterized in that mixtures of olefin with 8, 9, 12 or 16 carbon atoms are used as hydroformylation starting materials.

3. A process according to claim 1 or 2, characterized in that the reaction mixture of the hydroformylation is hydrogenated at elevated temperature and high pressure, in a carrier catalyst, which contains copper, nickel and chromium as active components.

4. A process according to claim 3, characterized in that a carrier catalyst is used which as active components contains copper and nickel in concentrations of respectively 0.3 to 15% by weight, chromium in a concentration of 0.05 to 3.5% by weight and a alkali metal component in a concentration of 0.01 to 1.6% by weight, respectively based on the carrier catalyst.

5. A process according to claim 4, characterized in that the concentration of the alkali metal component is 0.2-1.2% by weight.

6. A process according to claim 4, characterized in that the carrier catalyst does not contain any alkali metal component.

7. A process according to any of claims 1 to 6, characterized in that the carrier material of the catalyst is silicon dioxide or aluminum oxide.

8. A process according to any of claims 1 to 7, characterized in that the active catalyst components are homogeneously distributed in the pores of the carrier material.

9. A process according to any of claims 1 to 7, characterized in that the said catalyst components are enriched homogeneously in the edge areas of the carrier material.

10. A process according to any of claims 1 to 9, characterized in that the hydrogenation is carried out continuously or discontinuously in a liquid phase.

11. A process according to any of claims 1 to 10, characterized in that the hydrogenation is carried out in liquid phase under a total pressure of 5 to 30 bar.

12. A method according to claim 11, characterized in that the total pressure is from 15 to 25 bar.

13. A process according to any of claims 1 to 12, characterized in that the hydrogenation is carried out at 120 to 220 ° C.

14. A method according to claim 13, characterized in that the temperature is from 140 to 180 ° C.

15. A process according to any of claims 1 to 14, characterized in that the hydrogenation is carried out in liquid phase and with liquid loads of 5-100 m3 per square meter cross section of the empty reactor and hour.

16. A process according to claim 15, characterized in that the liquid loading is 15-50 m3 per m2 of empty reactor cross section and hour.

17. A process according to any of claims 1 to 16, characterized in that the hydrogenation mixture is distilled off and the olefins are fed back to the hydroformylation.

18. A process according to claim 17, characterized in that 2 to 40% of readily boiling substances are blocked from the olefin circulation.