Use of static mixer in preparation of alicyclic carboxylic acids and esters thereof

Abstract

The invention relates to the use of a static mixer in the preparation of cycloaliphatic carboxylic acids and their esters. The present invention is in the field of production of cycloaliphatic compounds by cyclohydrogenation of aromatic compounds. In the context of the invention there is provided a process for preparing cycloaliphatic compounds, preferably cycloaliphatic carboxylic acids and esters thereof, using a static mixer, as well as an apparatus for carrying out the process.

Description

FIELD OF THE INVENTION

[0001] The present invention belongs to the field of preparing alicyclic compounds by ring hydrogenation of aromatic compounds. In the context of the present invention, there are provided a method for preparing alicyclic compounds, preferably alicyclic carboxylic acids and their esters, using a static mixer, and an apparatus for carrying out the method. BACKGROUND OF THE INVENTION

[0002] Alicyclic polycarboxylic acid esters, such as esters of cyclohexane-1,2-dicarboxylic acid, are used as lubricant components and metalworking aids. They are also used as plasticizers in polyolefin and PVC applications.

[0003] For the plasticization of PVC, esters of phthalic acid, such as dinonyl phthalate or didecyl phthalate, are mainly used. The use of these phthalates is increasingly controversial in the public, and their use in plastics may be restricted. Alicyclic polycarboxylic acid esters, some of which have been described in the literature as plasticizers for plastics, can be a suitable choice as possible substitutes for restricted plasticizers.

[0004] In most cases, the most economical way to prepare alicyclic polycarboxylic acid esters is the ring hydrogenation of the corresponding aromatic polycarboxylic acid esters (such as the above-mentioned phthalates). For this purpose, several methods are known:

[0005] US 3027398 discloses the hydrogenation of dimethyl terephthalate over a supported ruthenium catalyst at 110 °C to 140 °C and 35 to 105 bar.

[0006] In DE 2823165, aromatic carboxylic acid esters are hydrogenated over supported Ni, Ru, Rh, and / or Pd catalysts at 70 °C to 250 °C and 30 to 200 bar to obtain the corresponding alicyclic carboxylic acid esters.

[0007] WO 99 / 32427 and WO 00 / 78704 disclose methods for hydrogenating benzene polycarboxylic acid esters to obtain the corresponding alicyclic compounds.

[0008] The hydrogenation of aromatic compounds is carried out, for example, by reacting a reactant containing an aromatic compound in the liquid phase with a hydrogen-containing hydrogenation gas. For this purpose, the hydrogenation gas must be dissolved in the liquid phase.

[0009] When the hydrogenation gas and the liquid reactant are introduced into the hydrogenation unit, the hydrogen concentration entering the liquid phase from the gas phase increases along the length of the hydrogenation unit. This results in different reaction rates within the hydrogenation unit and thus different space-time yields in the hydrogenation unit. Overall, this concentration gradient leads to a reduction in the total yield of the hydrogenation process.

[0010] Accordingly, a main object of the present invention is to provide a process for preparing alicyclic compounds (preferably alicyclic carboxylic acids and their esters), which process enables a substantially constant space-time yield to be achieved over the entire length of the hydrogenation unit. Summary of the Invention

[0011] The main object of the present invention is achieved by providing a process for preparing one or more alicyclic compounds, the process comprising the following steps:

[0012] i. providing a stream A of one or more aromatic compounds and a stream B of hydrogen-containing hydrogenation gas;

[0013] ii. contacting the streams A and B provided in step i. by means of at least 1 to at most 8 static mixers (4) to obtain a mixed stream C (5), and introducing the stream C (5) into a hydrogenation unit (6);

[0014] iii. hydrogenating one or more aromatic compounds in the hydrogenation unit (6) to obtain one or more corresponding alicyclic compounds;

[0015] iv. obtaining a product mixture comprising one or more alicyclic compounds.

[0016] A static mixer is a mixing element which, due to its internal geometry, is capable of mixing two or more input streams with one another. A static mixer comprises a pipe having flow elements and / or internal members. Mixing is accomplished by guiding the input streams over the flow elements in the pipe and thereby creating a turbulent flow. A static mixer is capable of mixing a substance system comprising two or more components having a gaseous, liquid, supercritical or particulate phase.

[0017] In the present case, at least one static mixer is used. It is also possible to use at most 8 static mixers connected in parallel or in series. For cost reasons, it is already advantageous to use the smallest possible number of static mixers. The static mixer comprises a pipe into which the two streams A and B are fed via a common inlet. At least one, preferably a plurality of, flow elements are arranged in the pipe. Desired mixing of the two streams A and B is achieved by means of the (one or more) flow elements and stream C is formed.

[0018] In the context of the present invention, it has been found that incorporating a static mixer into the hydrogenation unit causes the reactants to mix before entering the hydrogenation unit, thereby greatly increasing the hydrogen concentration in the liquid phase at the start. This results in an improved reaction in the start region of the hydrogenation unit.

[0019] In the context of the present invention, the term "alicyclic compound" is understood to mean those compounds having a saturated ring system with an aliphatic structure. Such compounds are also referred to as alicyclic compounds. Preferably, the alicyclic compounds obtained as products in the context of the present invention have a cyclohexane ring.

[0020] In the context of the present invention, "aromatic compound" is understood to mean those compounds having at least one ring system which contains 4n + 2 delocalized electrons in conjugated double bonds, free electron pairs or unoccupied p-orbitals according to Hückel's rule (Hückel-Regel). Preferably, the aromatic compounds used as reactants in the context of the present invention have a benzene ring.

[0021] "Hydrogen-containing hydrogenation gas" is a gas containing hydrogen. In the context of the reaction on which the present invention is based, in addition to the aromatic compound, hydrogen is also used as another reactant. In the hydrogenation reaction carried out, the double bonds in the ring of the aromatic compound used, preferably the double bonds in the benzene ring, are hydrogenated by the addition reaction of hydrogen and thus eliminated. This reaction is carried out in the presence of a solid catalyst. The hydrogen molecules in the hydrogen-containing hydrogenation gas are intermediately bonded to the metal atoms of the catalyst, and the bond between the two hydrogen atoms in the hydrogen molecule is weakened and can interact with the electron-rich multiple bond (double bond). Hydrogenation occurs when two hydrogen atoms are formally transferred to the double bond in each case. This eliminates the double bond in the aromatic compound and gives an alicyclic compound.

[0022] The hydrogenation gas used can be any hydrogen-containing gas mixture that does not contain harmful amounts of catalyst poisons (such as carbon monoxide or hydrogen sulfide). The use of an inert gas is optional, and hydrogen with a purity greater than 95%, especially greater than 98%, is preferably used. The inert gas component can be, for example, nitrogen or methane. Preferably, the amount of hydrogen present in the hydrogenation unit is such that the hydrogen is present in excess, especially in an excess of 1% to 200%, preferably in an excess of 3% to 100%, and particularly preferably in an excess of 5% to 50%, based on the stoichiometric amount required to achieve the possible or desired conversion in the hydrogenation unit. Setting a sufficient excess of hydrogen can have a beneficial effect on the complete hydrogenation of the aromatic bond.

[0023] In the context of the present invention, "hydrogenation unit" is understood to mean a hydrogenation reactor or a plurality of reactors connected in series or a plurality of reactors connected in parallel with each other or a reactor group comprising reactors connected in parallel and in series. Thus, it is understood to mean a reactor or a reactor arrangement that can perform the reactor function in the process according to the present invention.

[0024] Each hydrogenation unit can be charged with fresh hydrogen. However, in order to minimize hydrogen consumption and discharge losses caused by waste gas, it is purposeful to use the waste gas of one hydrogenation unit as the hydrogenation gas of another or the same hydrogenation unit. In addition, the waste gas of one hydrogenation unit can be reused as fresh hydrogen after post-treatment. For example, in a process carried out in two hydrogenation units connected in series, each having a reactor, it is advantageous to feed fresh hydrogen into the first hydrogenation unit and direct the waste gas of the first hydrogenation unit to the second hydrogenation unit. In this case, the reactants and the hydrogenation gas can flow through the hydrogenation units in the opposite order, or be pre-mixed, for example, by a static mixer. During the process of this method, it is advantageous to keep the hydrogen excess below 30%, especially below 20% based on the stoichiometric requirement.

[0025] The hydrogenation according to the invention is preferably carried out in a liquid / gas mixed phase or a liquid phase in two hydrogenation units connected in series. The first hydrogenation unit operates in a loop mode, that is, a part of the hydrogenation discharge from the first hydrogenation unit is directed to the top of the first hydrogenation unit together with the fresh reactants. Preferably, the re-feed is achieved by introducing into a static mixer or feeding without a static mixer. Another part of the discharge of the first hydrogenation unit is hydrogenated in the second hydrogenation unit in a through-flow mode. Preferably, a static mixer can also be present in the feed conduit leading to the second hydrogenation unit. In addition to one large hydrogenation unit in the loop mode, a plurality of small hydrogenation units in the loop mode arranged in series or parallel can also be used. In addition to one large hydrogenation unit flowing in the through-flow mode, a plurality of hydrogenation units connected in series or parallel to each other can also be operated. Preferably, a static mixer is present in each feed conduit of each hydrogenation unit. Preferably, one hydrogenation unit operating in the loop mode and one hydrogenation unit operating in the through-flow mode are used.

[0026] The hydrogenation can be carried out in the absence or preferably in the presence of a solvent. The solvent used can be any liquid that forms a homogeneous solution with the reactants and products, is inert under the hydrogenation conditions, and can be easily separated from the products. The solvent can also be a mixture of multiple substances and can optionally contain water. Preferably, when a solvent is present, the solvent is also mixed with the reactants provided in step i through a static mixer.

[0027] For example, the following substances can be used as solvents: straight-chain or cyclic ethers such as tetrahydrofuran or dioxane, and aliphatic alcohols in which the alkyl group has 1 to 13 carbon atoms.

[0028] The alcohols preferably used as solvents are isopropyl alcohol, n-butanol, isobutanol, n-pentanol, 2-ethylhexanol, nonanol, industrial nonanol mixture, decanol, industrial decanol mixture, tridecanol.

[0029] When using an alcohol as a solvent, it may be expedient to use the corresponding alcohol or corresponding alcohol mixture that will form during the saponification of the product. This will exclude the possibility of forming by-products through transesterification. Another preferred solvent is the hydrogenation product itself.

[0030] By using a solvent, the concentration of aromatic compounds in the feed to the hydrogenation unit can be restricted, enabling better temperature control in the hydrogenation unit. This can minimize side reactions and thus increase the product yield. Preferably, the aromatic compound content in the feed to the hydrogenation unit is between 1 wt% and 35 wt%, preferably between 2 wt% and 25 wt%, based on the total amount of the reactants. For a hydrogenation unit operating in a recycle mode, the required concentration range can be adjusted by the recycle ratio (the ratio of the recycled hydrogenation effluent to the amount of reactants used). BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Design examples of the method according to the invention are shown. The following will use Figure 1 the shown design examples to exemplarily describe the method according to the invention. DETAILED DESCRIPTION

[0032] The reactants are supplied to a static mixer via at least two pipes (1, 2), and these two pipes are optionally combined to form a single stream (3). Preferably, one of the two pipes contains a hydrogen-containing hydrogenation gas, while the other contains a liquid aromatic compound. Then they are introduced into the static mixer (4) and supplied as a homogeneous mixture via pipe (5) to a hydrogenation unit (6), where a hydrogenation reaction takes place. The product stream (7) contains a mixture of the alicyclic compound as the product and the reactants with a remaining residual concentration.

[0033] Preferably, the product stream (7) at the outlet of the hydrogenation unit contains less than 0.3 wt%, preferably less than 0.1 wt%, especially less than 0.05 wt%, and particularly preferably less than 0.005 wt% of the aromatic compound used as a reactant.

[0034] Preferably, the static mixer has a geometry such that the fluid in the static mixer has a Reynolds number greater than 100, preferably greater than 200, especially greater than 500, and particularly preferably greater than 900.

[0035] A person skilled in the art can determine the Reynolds number based on the geometry of the static mixer. The general formula for the Reynolds number is known to a person skilled in the art.

[0036] Further preferably, the static mixer has a geometry that mixes the hydrogenation gas provided in step i with the aromatic compounds of the provided liquid phase such that hydrogen from the hydrogen-containing hydrogenation gas is present in the liquid phase at an approximately saturated concentration at the end of the static mixer. A person skilled in the art can determine the saturated concentration in the liquid phase.

[0037] In the context of the present invention, "approximately saturated concentration" is understood to mean that the concentration of hydrogen in the liquid phase is at most 15%, preferably at most 10%, particularly preferably at most 5%, and very particularly preferably at most 1% lower than the saturated concentration. This means, for example, that if the saturated concentration of hydrogen in the liquid phase is 1 g / L, a hydrogen concentration of 0.85 g / L in the liquid phase also means the presence of the saturated concentration.

[0038] Therefore, further preferably, the static mixer has a design selected from the following mixer types: Kenics mixer, Sulzer SMV mixer, Sulzer SMX mixer, Fluitec CSE mixer, and Ross-ISG mixer, preferably the Kenics mixer design.

[0039] The Kenics mixer has a geometry that radially conveys the input stream along the tube wall direction through spiral mixing elements and then returns it towards the center. The combination of alternating left-handed and right-handed elements results in an additional reversal of the flow direction and flow distribution (Stromaufteilung). The input stream is mixed by these flow profiles (Flieβprofile).

[0040] In the context of the present invention, preferably, the hydrogenation of the aromatic compounds provided in step i is carried out using the hydrogen-containing gas provided in step i on one or more solid catalysts arranged in a fixed bed of the hydrogenation unit.

[0041] Further preferably, the solid catalyst contains at least one metal from the eighth subgroup of the periodic table. Preferably, platinum, rhodium, palladium, cobalt, nickel, or ruthenium or a mixture of two or more thereof is used as the active metal, and ruthenium is particularly used as the active metal.

[0042] In addition to the above metals, the catalyst preferably additionally contains at least one metal from the first and / or seventh subgroups of the periodic table. In addition to the metals of the eighth subgroup of the periodic table, rhenium and / or copper are preferably used.

[0043] The catalyst used in this method is the metal as defined above applied to a support material. The support material used is preferably a material containing micropores (pore diameter less than 2 nm), mesopores (pore diameter from 2 to 50 nm), and macropores (pore diameter greater than 50 nm). For example, in terms of pore types, support materials with the following pore combinations are available:

[0044] a) Only mesopores,

[0045] b) micropores and mesopores,

[0046] c) mesopores and macropores,

[0047] d) micropores, mesopores and macropores,

[0048] e) micropores and macropores.

[0049] Activated carbon, silicon carbide, alumina, silica, aluminosilicate, titanium dioxide, zirconium dioxide, magnesium oxide and / or zinc oxide, or mixtures thereof are preferably used as the carrier material.

[0050] Preferably used as the carrier material are solids that are substantially inert under hydrogenation conditions. These are, for example, activated carbon, silicon carbide, silica, titanium dioxide and / or zirconium dioxide, or mixtures of these compounds. Titanium dioxide is very particularly preferably used as the carrier material. Titanium dioxide exists in three modifications (anatase, rutile, brookite), of which anatase and rutile are the most common. The preferred carrier material is Aerolyst (Evonik Operations GmbH). This carrier material consists of 15% - 20% by mass of rutile and 80% - 85% by mass of anatase. Other suitable titanium dioxide carrier materials are, for example, carrier materials based on titanium oxides prepared by the sulfuric acid process. They usually contain >98% anatase.

[0051] In the process according to the invention, the hydrogenation in step iii. is carried out in the liquid phase or the gas phase. The hydrogenation can be carried out continuously or batchwise on a suspended catalyst or on a catalyst arranged in a fixed bed in the form of tablets. In the process according to the invention, hydrogenation is preferably carried out continuously on a catalyst arranged in a fixed bed, where the product / reactant phase is mainly liquid under the reaction conditions.

[0052] Preferably, the hydrogenation in step iii. is carried out at a pressure of 3 to 300 bar, preferably 15 to 200 bar, particularly preferably 50 to 150 bar.

[0053] Further preferably, the hydrogenation in step iii. is carried out at a temperature of 50°C to 250°C, preferably 70°C to 200°C. Due to the exothermic nature of the hydrogenation reaction, the reaction is not carried out at a fixed temperature but within the temperature range described herein. Thus, the temperature of the reaction mixture increases as it flows through the hydrogenation unit.

[0054] In the context of the process according to the invention, it is preferred to provide one or more aromatic carboxylic esters in step i, preferably one or more aromatic mono-, di- and polycarboxylic esters.

[0055] In the context of the process according to the invention, aromatic compounds, such as aromatic polycarboxylic acids and / or monocarboxylic acids or their derivatives, in particular their alkyl esters, can be converted into the corresponding alicyclic polycarboxylic acid compounds. Here, both the full esters and the partial esters can be hydrogenated. Full esters are understood to be compounds in which all acid groups have been esterified. Partial esters are compounds having at least one free acid group (or optionally an acid anhydride group) and at least one ester group.

[0056] If polycarboxylic acid esters are used in the process according to the invention, these polycarboxylic acid esters preferably contain 2, 3 or 4 ester functional groups.

[0057] In the context of the process according to the invention, it is preferred to provide in step i one or more benzene-, biphenyl-, naphthalene-, diphenyl ether-, anthracene-di- or -polycarboxylic acid esters. The alicyclic polycarboxylic acids or their derivatives obtained by the process according to the invention consist of one or more C6 rings which are optionally linked or fused via carbon-carbon bonds.

[0058] Further preferably, in step i one or more aromatic carboxylic acid esters having an alcohol component are provided, the alcohol component being selected from branched or unbranched alkoxyalkyls, cycloalkyls and / or alkyls having 1 to 25 carbon atoms, preferably C8-C 10 phthalates, C8-C 10 terephthalates, C8-C 10 isophthalates and C8-C 10 trimellitates, particularly preferably di-2-ethylhexyl phthalate, diisononyl phthalate, di-2-ethylhexyl terephthalate, diisononyl terephthalate, di-2-ethylhexyl isophthalate, diisononyl isophthalate, tri-2-ethylhexyl trimellitate and triisononyl trimellitate.

[0059] Here, C8 preferably denotes 2-ethylhexyl or n-octyl, C9 denotes isononyl, C 10 denotes isodecyl or 2-propylheptyl.

[0060] The process is preferably a process for hydrogenating benzene-1,2-, -1,3- or -1,4-dicarboxylic acid esters and / or benzene-1,2,3-, -1,2,4- or -1,3,5-tricarboxylic acid esters, that is to say, obtaining isomers of cyclohexane-1,2-, -1,3- or -1,4-dicarboxylic acid esters or cyclohexane-1,2,3-, -1,3,5- or -1,2,4-tricarboxylic acid esters.

[0061] In the process according to the invention, esters of the following aromatic carboxylic acids can be used, for example: naphthalene-1,2-dicarboxylic acid, naphthalene-1,3-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-1,6-dicarboxylic acid, naphthalene-1,7-dicarboxylic acid, naphthalene-1,8-dicarboxylic acid, phthalic acid (benzene-1,2-dicarboxylic acid), isophthalic acid (benzene-1,3-dicarboxylic acid), terephthalic acid (benzene-1,4-dicarboxylic acid), benzene-1,2,3-tricarboxylic acid, benzene-1,2,4-tricarboxylic acid (trimellitic acid), benzene-1,3,5-tricarboxylic acid (trimesic acid), benzene-1,2,3,4-tetracarboxylic acid. It is also possible to use acids formed from the abovementioned acids by substituting one or more hydrogen atoms bonded to the aromatic ring by alkyl, cycloalkyl or alkoxyalkyl groups.

[0062] Preference is given to using, for example, alkyl esters, cycloalkyl esters and alkoxyalkyl esters of the abovementioned acids, where these groups independently of one another contain from 1 to 25 carbon atoms, in particular from 3 to 15 carbon atoms, very particularly from 8 to 13 carbon atoms and especially 9 carbon atoms. These groups can be straight-chain or branched. If the reactant has more than one ester group, these groups can be identical or different.

[0063] In the process according to the invention, as the aromatic polycarboxylic esters, the following compounds can be used, for example: monomethyl terephthalate, dimethyl terephthalate, diethyl terephthalate, di-n-propyl terephthalate, di-n-butyl terephthalate, diisobutyl terephthalate, di-tert-butyl terephthalate, dipentyl terephthalate, monoethylene glycol terephthalate, diethylene glycol terephthalate, n-octyl terephthalate, diisooctyl terephthalate, di-2-ethylhexyl terephthalate, di-n-nonyl terephthalate, diisononyl terephthalate, di-2-propylheptyl terephthalate, di-n-decyl terephthalate, di-n-undecyl terephthalate, diisodecyl terephthalate, diisododecyl terephthalate, ditridecyl terephthalate, di-n-octadecyl terephthalate, diisooctadecyl terephthalate, di-n-eicosyl terephthalate, monocyclohexyl terephthalate; monomethyl phthalate, dimethyl phthalate, di-n-propyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, di-tert-butyl phthalate, monoethylene glycol phthalate, diethylene glycol phthalate, di-n-octyl phthalate, diisooctyl phthalate, di-2-ethylhexyl phthalate, di-n-nonyl phthalate, diisononyl phthalate, di-n-decyl phthalate, di-2-propylheptyl phthalate, diisodecyl phthalate, di-n-undecyl phthalate, diisoundecyl phthalate, ditridecyl phthalate, di-n-octadecyl phthalate, diisooctadecyl phthalate, di-n-eicosyl phthalate, monocyclohexyl phthalate; dicyclohexyl phthalate, monomethyl isophthalate, dimethyl isophthalate, diethyl isophthalate, di-n-propyl isophthalate, di-n-butyl isophthalate, diisobutyl isophthalate, di-tert-butyl isophthalate, monoethylene glycol isophthalate, diethylene glycol isophthalate, di-n-octyl isophthalate, diisooctyl isophthalate, di-2-ethylhexyl isophthalate, di-n-nonyl isophthalate, diisononyl isophthalate, di-n-decyl isophthalate, diisodecyl isophthalate, di-n-undecyl isophthalate, diisododecyl isophthalate, di-n-dodecyl isophthalate, ditridecyl isophthalate, di-n-octadecyl isophthalate, diisooctadecyl isophthalate, di-n-eicosyl isophthalate, monocyclohexyl isophthalate.

[0064] The process according to the invention is in principle also applicable to benzoic acid and its esters. This is understood to mean not only alkyl benzoates, but also benzoates of diols, such as ethylene glycol dibenzoate, diethylene glycol dibenzoate, triethylene glycol dibenzoate or propylene glycol dibenzoate. The alcohol component of the alkyl benzoates can consist of 1 to 25 carbon atoms, preferably 8 to 13 carbon atoms, and is in each case straight-chain or branched.

[0065] On an industrial scale, aromatic esters, especially fully esters, are usually preferably prepared from alcohol mixtures. Suitable alcohol mixtures are, for example:

[0066] A C5 alcohol mixture prepared by hydroformylation of linear butene followed by hydrogenation; a C5 alcohol mixture prepared by hydroformylation and subsequent hydrogenation of a butene mixture containing linear butene and isobutene; a C6 alcohol mixture prepared by hydroformylation and subsequent hydrogenation of pentene or a mixture of two or more pentenes; a C7 alcohol mixture prepared by hydroformylation and subsequent hydrogenation of the trimerization of ethylene or the dimerization of propylene or a mixture of hexene isomers or another hexene isomer mixture; a C8 alcohol mixture prepared by aldol condensation of n-butyraldehyde and subsequent hydrogenation, such as 2-ethylhexanol (2 isomers); a C9 alcohol mixture prepared by dimerization, hydroformylation and hydrogenation of C4 olefins. The preparation of C9 alcohols can be carried out starting from a mixture of isobutene or linear butene or a mixture of linear butene and isobutene. The dimerization of C4 olefins can be carried out with various catalysts, such as proton acids, zeolites, organometallic nickel compounds or solid nickel-containing catalysts. The hydroformylation of the C8 olefin mixture can be carried out with a rhodium catalyst or a cobalt catalyst; a C 10 alcohol mixture; 2-propylheptanol (2 isomers) prepared by aldol condensation of valeraldehyde and subsequent hydrogenation; a C 10 alcohol mixture prepared by aldol condensation of a mixture of at least two C5 aldehydes and subsequent hydrogenation; a C 13 alcohol mixture prepared by hydroformylation and subsequent hydrogenation of hexavinyl, tetrapropylene or tributylene.

[0067] Other alcohol mixtures can be obtained by hydroformylation of an olefin or an olefin mixture followed by hydrogenation, said olefin or olefin mixture being produced, for example, in Fischer-Tropsch synthesis, hydrocarbon dehydrogenation, metathesis reaction, polygas process or other industrial processes.

[0068] Olefin mixtures of olefins with different carbon atom numbers can also be used for the preparation of alcohol mixtures.

[0069] In the process according to the invention, all ester mixtures prepared from aromatic polycarboxylic acids and the above alcohol mixtures can be used. According to the invention, esters prepared from phthalic acid or phthalic anhydride and a mixture of isomeric alcohols having 4 to 13 carbon atoms are preferably used.

[0070] Preferably, the process according to the invention comprises the following steps:

[0071] i. Provide an aromatic compound which is one or more esters selected from phthalic acid, isophthalic acid, terephthalic acid and trimellitic acid, particularly preferably selected from di-n-butyl terephthalate, dipentyl terephthalate, di-2-ethylhexyl terephthalate, diisononyl terephthalate, dipentyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate, dipentyl isophthalate, di-2-ethylhexyl isophthalate, diisononyl isophthalate, tripentyl trimellitate, tri-2-ethylhexyl trimellitate, triisononyl trimellitate or a mixture thereof,

[0072] and a hydrogen-containing hydrogenation gas;

[0073] ii. Contact the substances provided in step i. through a static mixer and introduce them into a hydrogenation unit (6);

[0074] iii. Hydrogenate one or more aromatic compounds in the hydrogenation unit (6) to obtain one or more corresponding alicyclic compounds;

[0075] iv. Obtain a product mixture containing one or more alicyclic compounds selected from dialkyl cyclohexane-1,2-dicarboxylate, dialkyl cyclohexane-1,3-dicarboxylate, dialkyl cyclohexane-1,4-dicarboxylate and cyclohexane-1,2,4-tricarboxylate, particularly preferably selected from di-n-butyl cyclohexane-1,4-dicarboxylate, dipentyl cyclohexane-1,4-dicarboxylate, di-2-ethylhexyl cyclohexane-1,4-dicarboxylate, diisononyl cyclohexane-1,4-dicarboxylate, dipentyl cyclohexane-1,2-dicarboxylate, di-2-ethylhexyl cyclohexane-1,2-dicarboxylate, diisononyl cyclohexane-1,2-dicarboxylate, dipentyl cyclohexane-1,3-dicarboxylate, di-2-ethylhexyl cyclohexane-1,3-dicarboxylate, diisononyl cyclohexane-1,3-dicarboxylate, tripentyl cyclohexane-1,2,4-tricarboxylate, tri-2-ethylhexyl cyclohexane-1,2,4-tricarboxylate, triisononyl cyclohexane-1,2,4-tricarboxylate.

[0076] The resulting product depends on the reactants used. For example, when diisononyl phthalate is used as the reactant, diisononyl cyclohexane-1,2-dicarboxylate is obtained as the product. Thus, di-2-ethylhexyl cyclohexane-1,2-dicarboxylate is obtained from di-2-ethylhexyl phthalate.

[0077] Preferably, the method according to the present invention comprises the following steps:

[0078] i. Provide a reactant containing diisononyl phthalate (DINP) or di-2-ethylhexyl phthalate (DEHP) and a hydrogen-containing hydrogenation gas;

[0079] ii. Contact the substances provided in step i. through a static mixer and introduce them into the hydrogenation unit (6);

[0080] iii. Hydrogenate one or more aromatic compounds in the hydrogenation unit (6) to obtain the corresponding alicyclic compounds;

[0081] iv. Obtain a product mixture containing diisononyl cyclohexane-1,2-dicarboxylate or di-2-ethylhexyl cyclohexane-1,2-dicarboxylate.

[0082] In addition, for example, when using diisononyl terephthalate as a reactant, diisononyl cyclohexane-1,4-dicarboxylate is obtained as a product. Thus, di-2-ethylhexyl cyclohexane-1,4-dicarboxylate is obtained from di-2-ethylhexyl terephthalate.

[0083] Preferably, the method according to the present invention comprises the following steps:

[0084] i. Provide a reactant containing diisononyl terephthalate or di-2-ethylhexyl terephthalate and a hydrogen-containing hydrogenation gas;

[0085] ii. Contact the substances provided in step i. through a static mixer and introduce them into the hydrogenation unit (6);

[0086] iii. Hydrogenate the one or more aromatic compounds in the hydrogenation unit (6) to obtain the corresponding alicyclic compounds;

[0087] iv. Obtain a product mixture containing diisononyl cyclohexane-1,4-dicarboxylate or di-2-ethylhexyl cyclohexane-1,4-dicarboxylate.

[0088] In addition, for example, when using triisononyl trimellitate as a reactant, triisononyl cyclohexane-1,2,4-tricarboxylate is obtained as a product. Thus, tri-2-ethylhexyl cyclohexane-1,2,4-tricarboxylate is obtained from tri-2-ethylhexyl trimellitate.

[0089] Preferably, the method according to the present invention comprises the following steps:

[0090] i. Provide a reactant containing triisononyl trimellitate (TINTM) or tri-2-ethylhexyl trimellitate (TOTM) and a hydrogen-containing hydrogenation gas;

[0091] ii. Contact the substances provided in step i. through a static mixer and introduce them into the hydrogenation unit (6);

[0092] iii. Hydrogenate the one or more aromatic compounds in the hydrogenation unit (6) to obtain the corresponding alicyclic compounds;

[0093] iv. A product mixture containing tris(isononyl) cyclohexane-1,2,4-tricarboxylate or tris(2-ethylhexyl) cyclohexane-1,2,4-tricarboxylate is obtained.

[0094] The method according to the invention is preferably carried out under the following conditions.

[0095] A Kenics mixer is installed in the feed of the hydrogenation unit, which results in a Reynolds number greater than 100 in the mixer. In the mixer feed, the concentration of the aromatic compound as a reactant is between 5% by mass and 30% by mass, especially between 8% by mass and 15% by mass. In the output stream of the hydrogenation unit, the concentration of the reactant is between 0.3% by mass and 8% by mass, especially between 1.5% by mass and 4% by mass.

[0096] After introducing the output stream of the static mixer into the hydrogenation unit, the hydrogenation reaction is carried out on the catalyst.

[0097] The catalyst in the hydrogenation unit has a liquid hourly space velocity (LHSV, liters of fresh reactant per liter of catalyst per hour) of 0.1 to 5 h -1 , especially 0.5 to 3 h -1 .

[0098] The area load in the hydrogenation unit is 25 to 140 m 3 / m 2 / h, especially 50 to 90 m 3 / m 2 / h.

[0099] The average hydrogenation temperature in the hydrogenation unit is 70 to 150 °C, especially 80 to 120 °C.

[0100] The hydrogenation pressure in the hydrogenation unit is 25 to 200 bar, especially 80 to 110 bar.

[0101] This method variant is particularly suitable for the hydrogenation of phthalates, especially isononyl phthalate (as the isomer mixture "diisononyl phthalate", e.g., from Evonik OXENO GmbH & Co. KG 9).

[0102] Another aspect of the invention is to provide an apparatus for implementing the method of the invention, which comprises at least one hydrogenation unit (6), a static mixer (4) and one or more feed streams (1, 2), wherein the static mixer is configured such that the feed streams A and B (1, 2) contact each other and then are introduced into the hydrogenation unit (6) via the stream C (5).

[0103] The apparatus according to the invention preferably comprises feed streams of two, three, four or more static mixers.

[0104] Preferably, the hydrogenation unit (6) has one or more solid catalysts, preferably wherein the solid catalyst comprises at least one metal of subgroup VIII of the Periodic Table of the Elements, particularly preferably ruthenium. The description of the catalyst used herein applies equally.

[0105] Further preferably, a mixture of an aromatic compound and the corresponding alicyclic compound is present in the hydrogenation unit, preferably a mixture of an aromatic carboxylic acid ester having an alcohol component and the corresponding alicyclic compound, the alcohol component being selected from branched or unbranched alkoxyalkyl, cycloalkyl and / or alkyl having 1 to 25 carbon atoms, and the aromatic carboxylic acid ester preferably being selected from C8-C 10 phthalates, C8-C 10 terephthalates, C8-C 10 isophthalates and C8-C 10 trimellitates, particularly preferably di-2-ethylhexyl phthalate, diisononyl phthalate, di-2-ethylhexyl terephthalate, diisononyl terephthalate, di-2-ethylhexyl isophthalate, diisononyl isophthalate, tri-2-ethylhexyl trimellitate and triisononyl trimellitate, diisononyl phthalate and / or didecyl phthalate, and diisononyl cyclohexanedicarboxylate and / or didecyl cyclohexanedicarboxylate and the corresponding alicyclic compounds.

[0106] Another aspect of the invention is the use of a static mixer for bringing two or more feed streams into contact before introduction into one or more hydrogenation units, preferably for bringing an aromatic compound and a hydrogen-containing hydrogenation gas into contact, preferably wherein the mixer has a Kenics mixer design.

[0107] Preferably, the static mixer has a geometry such that the fluid in the static mixer has a Reynolds number greater than 100, preferably greater than 200, particularly preferably greater than 500, and most preferably greater than 900.

[0108] Further preferably, the static mixer has a geometry such that the hydrogenation gas provided in step i is mixed with the provided liquid-phase aromatic compound such that hydrogen from the hydrogen-containing hydrogenation gas is present in the liquid phase at an approximately saturated concentration at the end of the static mixer.

[0109] In the context of the present invention, preference is given to the use of the alicyclic polycarboxylic acid esters prepared according to the invention as plasticizers in plastics. Preferred plastics are PVC, homopolymers or copolymers based on ethylene, propylene, butadiene, vinyl acetate, glycidyl acrylate, glycidyl methacrylate, acrylates, acrylates having an alkyl group with a branched or unbranched alcohol having 1 to 10 carbon atoms bonded to the oxygen atom of the ester group, styrene, acrylonitrile, cyclic olefins.

[0110] Representatives of the above categories may mention, for example, the following plastics:

[0111] Polyacrylates having the same or different alkyl groups having 4 to 8 carbon atoms bonded to the oxygen atom of the ester group, in particular polyacrylates having n-butyl, n-hexyl, n-octyl and 2-ethylhexyl groups as well as isononyl groups, polymethacrylates, polymethyl methacrylate, acrylate-butyl acrylate copolymers, methacrylate-butyl methacrylate copolymers, ethylene-vinyl acetate copolymers, chlorinated polyethylene, nitrile rubber, acrylonitrile-butadiene-styrene copolymers, ethylene-propylene copolymers, ethylene-propylene-diene copolymers, styrene-acrylonitrile copolymers, acrylonitrile-butadiene rubber, styrene-butadiene elastomers, methacrylate-styrene-butadiene copolymers and / or nitrocellulose.

[0112] Furthermore, the alicyclic polycarboxylic acid esters prepared according to the invention can be used to modify plastic mixtures, such as mixtures of polyolefins and polyamides.

[0113] In addition to the above uses, the alicyclic polycarboxylic acid esters prepared according to the invention can be used as components of lubricating oils, coolants and metalworking fluids. They can also be used as components of paints, coatings, inks and adhesives.

Claims

1. A method for preparing one or more alicyclic compounds, comprising the steps of: i. providing a stream A of one or more aromatic compounds and a stream B of a hydrogenation gas containing hydrogen; ii. contacting the streams A and B provided in step i. through at least 1 to at most 8 static mixers (4) to obtain a mixed stream C (5), and introducing the stream C (5) into the hydrogenation unit (6); iii. hydrogenating the one or more aromatic compounds in a hydrogenation unit (6) to obtain one or more corresponding alicyclic compounds; iv. A product mixture (7) comprising one or more alicyclic compounds is obtained.

2. The method according to claim 1, wherein the static mixer comprises a pipeline, into which the two material flows A and B are fed via a common inlet, wherein at least one, preferably a plurality of flow elements are arranged in the pipeline, thereby achieving a desired mixing of the two material flows A and B.

3. The method according to any of the preceding claims, wherein the static mixer has a design selected from the following mixer types: Kenics mixer, Sulzer SMV mixer, Sulzer SMX mixer, Fluitec CSE mixer and Ross-ISG mixer, preferably the Kenics mixer design.

4. The process according to any one of the preceding claims, wherein the hydrogenation in step iii. is carried out using the hydrogenation gas containing hydrogen provided in step i. over a solid catalyst arranged in a fixed bed in the hydrogenation unit (6).

5. The process according to claim 4, wherein the catalyst comprises at least one metal of the eighth subgroup of the periodic table, preferably ruthenium.

6. The process according to any one of the preceding claims, wherein the hydrogenation in step iii. is carried out at a pressure of 3 to 300 bar, preferably 15 to 200 bar, particularly preferably 50 to 150 bar.

7. The process according to any one of the preceding claims, wherein the hydrogenation in step iii. is carried out at a temperature of 50 to 250°C, preferably 70 to 200°C.

8. The process according to any one of the preceding claims, wherein one or more aromatic carboxylic acid esters, preferably one or more aromatic mono-, di- and polycarboxylic acid esters, are provided in step i.

9. The process according to any one of the preceding claims, wherein one or more benzene-, biphenyl-, naphthalene-, diphenyl ether-, anthracene-di- or polycarboxylic acid esters are provided in step i.

10. The process according to any one of the preceding claims, wherein in step i, one or more aromatic carboxylic acid esters having an alcohol component selected from branched or unbranched alkoxyalkyl, cycloalkyl and / or alkyl groups having 1 to 25 carbon atoms are provided, the aromatic carboxylic acid esters being preferably C8-C 10 Phthalate, C8-C 10 Terephthalate, C8-C 10 Isophthalates and C8-C 10 The trimellitic acid esters are particularly preferably di-2-ethylhexyl phthalate, diisononyl phthalate, di-2-ethylhexyl terephthalate, diisononyl terephthalate, di-2-ethylhexyl isophthalate, diisononyl isophthalate, tri-2-ethylhexyl trimellitate and triisononyl trimellitate. 11 . The method according to claim 1 , wherein the static mixer has a geometry such that the fluid in the static mixer has a Reynolds number of greater than 100, preferably greater than 200, in particular greater than 500, particularly preferably greater than 900.

12. An apparatus for implementing the method according to any one of claims 1 to 11, comprising at least one hydrogenation unit (6), a static mixer (4) and one or more feed streams (1, 2), wherein the static mixer is configured so that the feed streams (1, 2) are in contact with each other and then introduced into the hydrogenation unit (6) via the stream (5).

13. The apparatus according to claim 12, wherein the hydrogenation unit (6) has one or more solid catalysts, preferably wherein the solid catalyst comprises at least one metal of the eighth subgroup of the periodic table, particularly preferably ruthenium.

14. The apparatus according to any one of claims 12 or 13, wherein a mixture of aromatic compounds and corresponding alicyclic compounds is present in the hydrogenation unit, preferably a mixture of aromatic carboxylic acid esters and their corresponding alicyclic compounds having an alcohol component selected from branched or unbranched alkoxyalkyl, cycloalkyl and / or alkyl groups having 1 to 25 carbon atoms, the aromatic carboxylic acid esters being preferably selected from C8-C 10 Phthalate, C8-C 10 Terephthalate, C8-C 10 Isophthalates and C8-C 10 Trimellitic acid esters, particularly preferably di-2-ethylhexyl phthalate, diisononyl phthalate, di-2-ethylhexyl terephthalate, diisononyl terephthalate, di-2-ethylhexyl isophthalate, diisononyl isophthalate, tri-2-ethylhexyl trimellitate and triisononyl trimellitate, diisononyl phthalate and / or didecyl phthalate as well as diisononyl cyclohexanedicarboxylate and / or didecyl cyclohexanedicarboxylate and their corresponding alicyclic compounds.

15. Use of a static mixer for contacting two or more feed streams, preferably aromatic compounds and a hydrogenation gas comprising hydrogen, prior to introduction into one or more hydrogenation units, preferably wherein the mixer is of Kenics mixer design.

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