Catalyst composition and use thereof in preparation of isomeric carboxylate ester by hydroesterification of highly branched olefin

Abstract

Disclosed are a catalyst composition, and a use thereof in the preparation of an isomeric carboxylate ester by means of hydroesterification of a highly branched olefin. The catalyst composition comprises a palladium compound, a phosphorus-containing ligand, and an acid promoter. The catalyst composition exhibits excellent activity, selectivity, and stability for a reaction converting highly branched olefins to isomeric carboxylate esters. The method for preparing an isomeric carboxylate ester by means of a hydroesterification reaction using a highly branched olefin as a starting material has a simple synthesis route, mild reaction conditions, and a high target product yield, and is suitable for industrial production.

Description

A catalyst composition and its application in the hydrogen esterification of highly branched olefins to prepare isomeric carboxylic acid esters Technical Field

[0001] This invention belongs to the field of catalytic chemistry and fine chemical synthesis, specifically relating to a catalyst composition containing a noble metal palladium compound and its application in the one-step preparation of isomeric carboxylic acid esters from highly branched olefins, carbon monoxide and fatty alcohols via hydrogen esterification. Background Technology

[0002] Highly branched isononanoic acid is an important organic chemical raw material that can be used to synthesize many high-value-added fine chemical products. For example, pentaerythritol isononanoate, obtained from isononanoic acid, is widely used in industries such as refrigeration oils, plasticizers, lubricants, fragrances and cosmetics, and high-end coatings due to its excellent thermal and antioxidant stability, wide liquid window (-70 to 320°C), low volatility, low hygroscopicity, low toxicity, and good compatibility with refrigerants, metals (e.g., copper, steel, aluminum), and elastic sealing rubbers.

[0003] Currently, isononanoic acid is mainly prepared through diisobutylene hydroformylation and carbonylation carboxylation. The diisobutylene hydroformylation method uses diisobutylene and syngas (CO / H2) as raw materials, and a phosphorus-containing ligand-modified Co or Rh compound as a catalyst. The hydroformylation reaction yields isononanal / isonononol, which is then oxidized to prepare isononanoic acid (see CN1900043A, CN112794796A, CN114149313A). This process not only requires expensive Rh catalysts, but the product isononanal undergoes an aldol condensation reaction to generate high-boiling-point byproducts, which is detrimental to the separation of catalyst and product. When using a Co catalyst, isononanal is prone to hydrogenation byproducts, resulting in the formation of large amounts of isononanol byproducts and severe deactivation of the Co catalyst. The carbonylation-carboxylation method uses diisobutylene, CO, and water as raw materials, with phosphorus-ligand-modified Pd compounds as catalysts, to produce isononanoic acid via carbonylation-carboxylation reactions (Angew. Chem. Int. Ed. 2019, 58, 14365-14373, Catal. Sci. Technol., 2021, 11, 2703-2707). This process requires water as a raw material, causing the water-sensitive phosphorus-ligand-modified Pd catalyst to be easily deactivated. In addition, the product isononanoic acid is highly polar and has a high boiling point, which is detrimental to the separation of homogeneous Pd catalyst and product isononanoic acid.

[0004] An emerging alternative technology route uses diisobutylene, carbon monoxide, and fatty alcohols as raw materials to prepare methyl isononanoate via hydrogen esterification, followed by hydrolysis of methyl isononanoate to obtain isononanoic acid, or transesterification of methyl isononanoate with a polyol to obtain pentaerythritol isononanoate. This technology route is simple, with mild reaction conditions and no accumulation of high-boiling-point byproducts. However, existing catalyst systems have low efficiency, poor stability, and are difficult to recycle. Catalyst deactivation leads to high process costs and pollution, making industrialization difficult. Summary of the Invention

[0005] The technical problem this invention aims to solve is the complexity, high cost, low catalyst efficiency, poor stability, and environmental pollution associated with the synthesis of highly branched isomeric carboxylic esters in existing technologies. To address these problems, this invention provides a high-performance hydrogen esterification catalyst and a method for its use in the hydrogen esterification of highly branched olefins to prepare isomeric carboxylic esters. The hydrogen esterification catalyst is simple to prepare and, when used in the hydrogen esterification of highly branched olefins to prepare isomeric carboxylic esters, exhibits advantages such as high reactant conversion rate, high target product yield, good stability, excellent recycling performance, mild applicable reaction conditions, and easy separation and regeneration from the product. This facilitates the green and efficient production of isomeric carboxylic esters, particularly methyl isononanoate.

[0006] In a first aspect, the present invention provides a catalyst composition comprising a palladium compound, a phosphorus-containing ligand, and an acid promoter, wherein the phosphorus-containing ligand comprises at least one phosphorus-containing ligand containing a P,O-hetero-group and a combination of a second phosphorus-containing ligand selected from one or more of tris(2-tert-butylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(o-tolyl) phosphite, tris(4-methoxyphenyl) phosphite, triphenyl phosphite, trimethylolpropane phosphite, triisopropyl phosphite, tris(tert-butyl) phosphite, triethyl phosphite, diethyl phenyl phosphite, diethyl diphenyl phosphite, and bidentate phosphite ligands La-Ld with the following structures.

[0007] In a second aspect, the present invention provides a method for preparing isomeric carboxylic acid esters by hydrogen esterification of highly branched olefins, characterized in that the method comprises:

[0008] S1. Olefin materials, C 1-4 Fatty alcohols, CO, and catalyst are introduced into a reactor to carry out a hydrogen esterification reaction to obtain a reaction mixture.

[0009] S2. The reaction mixture is subjected to gas-liquid separation to obtain gaseous material and liquid material;

[0010] S3. The liquid phase material is separated to obtain isomeric carboxylic acid esters and a first circulating catalyst;

[0011] In step S1, the catalyst material comprises the catalyst composition according to the first aspect;

[0012] The olefin material contains ≥70% by weight of highly branched C relative to the total weight of the olefin material. 5-16 Olefins.

[0013] In a third aspect, the present invention also provides the use of the catalyst composition according to the first aspect in a hydrogen esterification reaction, preferably in the preparation of isomeric carboxylic acid esters by hydrogen esterification of highly branched olefins, and particularly in the preparation of methyl isononanoate by hydrogen esterification of highly branched C8 olefins.

[0014] In a fourth aspect, the present invention also provides a system for preparing isomeric carboxylic acid esters by hydrogen esterification of highly branched olefins.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] (1) The catalyst can simultaneously catalyze the hydrogen esterification and isomerization of olefins, exhibiting high activity and excellent selectivity for target products;

[0017] (2) The catalyst exhibits excellent stability, is recyclable, and can be regenerated in a simple manner;

[0018] (3) Using highly branched olefins, CO and C 1-4 Using fatty alcohols as raw materials, isomeric carboxylic acid esters can be prepared in one step. The synthetic route is simple, the reaction conditions are mild, and the reaction process has very high atom economy.

[0019] (4) The raw materials are cheap and readily available, and the products are isomeric carboxylic esters, especially methyl isononanoate, which have high added value.

[0020] (5) The product isomeric carboxylic acid esters, especially methyl isononanoate, have good chemical stability, avoid the generation of other by-products, have no accumulation of high-boiling-point by-products, and have a Pd loss of <0.1ppm. The post-processing is simple and suitable for industrial production.

[0021] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0022] Figure 1. Results of 50 cycles of hydrogen esterification using a catalyst containing a combination of L2 ligand and tris(2,4-di-tert-butylphenyl) phosphite ligand;

[0023] Figure 2. Results of 20 cycles of hydrogen esterification reaction using a catalyst containing a combination of L2 ligand and tris(2,4-di-tert-butylphenyl) phosphite ligands with only phosphorus-containing ligands added;

[0024] Figure 3. Results of 19 cycles of hydrogen esterification using a catalyst containing a combination of Xantphos ligands and tris(2,4-di-tert-butylphenyl)phosphite ligands;

[0025] Figure 4. Results of 14 cycles of hydrogen esterification using a catalyst containing a combination of L2 and BIPHEPHOS ligands;

[0026] Figure 5. Results of five cycles of hydrogen esterification reaction using a catalyst containing only L2 as a single phosphorus ligand;

[0027] Figure 6. Results of one cycle of hydrogen esterification reaction using a catalyst containing only tris(2,4-di-tert-butylphenyl) phosphite as a single phosphorus-containing ligand;

[0028] Figure 7. Results of six cycles of hydrogen esterification using a catalyst containing a combination of L2 ligands and triphenylphosphine ligands;

[0029] Figure 8. A system flow diagram for the preparation of isomeric carboxylic acid esters by hydrogen esterification of highly branched olefins according to an embodiment of the present invention. Detailed Implementation

[0030] The specific embodiments of this application will be described in detail below. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0031] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0032] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0033] In this paper, the terms "phosphorus-containing ligands with P,O-hetero-groups" and "P,O-hetero-phosphorus-containing ligands" are used interchangeably, referring to ligands in which the P-atoms and O-atoms can form chelate structures with the metal center in the form of five- or six-membered rings, especially bidentate ligands.

[0034] In this article, "highly branched olefins" refers to olefins or mixtures thereof whose molecular structure contains at least one tertiary carbon atom or quaternary carbon atom, for example, olefins or mixtures thereof whose number of tertiary carbon atoms / quaternary carbon atoms accounts for more than 15% of the total number of carbon atoms, especially olefins or mixtures thereof containing at least one tertiary carbon atom and at least one quaternary carbon atom.

[0035] Hydrogen esterification catalyst

[0036] In a first aspect, the present invention provides a catalyst composition comprising at least one palladium compound, at least two phosphorus-containing ligands and at least one acid promoter, wherein the phosphorus-containing ligands comprise at least one phosphorus-containing ligand containing a P,O-heteromeric group and at least one second phosphorus-containing ligand, preferably comprising at least one bidentate phosphorus-containing ligand containing a P,O-heteromeric group and at least one phosphite-based phosphorus-containing ligand.

[0037] The inventors discovered that when using catalysts containing a single phosphorus-containing ligand in the catalytic hydrogen esterification of highly branched olefins to produce isomeric carboxylic esters, even though high catalytic activity was observed in the initial reaction and high yields of the target product were achieved, palladium black often precipitated in the reaction solution after one or more reactions. This indicated that the catalyst was significantly deactivated after one or more uses and was difficult to regenerate and restore its activity. Through extensive screening experiments, the inventors found that using catalysts containing two specific types of phosphorus-containing ligands significantly improved the catalyst's stability, allowing it to be recycled for the hydrogen esterification of highly branched olefins. Furthermore, even after multiple cycles, the catalyst's activity could be restored to high levels through simple regeneration. This significantly improves the cost-effectiveness and industrial feasibility of the hydrogen esterification technology for highly branched olefins to produce isomeric carboxylic esters.

[0038] According to some embodiments, the catalyst composition comprises a palladium compound, a phosphorus-containing ligand, and an acid promoter, wherein the phosphorus-containing ligand comprises at least one phosphorus-containing ligand containing a P,O-heterogroup and 1,2-bis(diphenylphosphine)ethane (DPPE), 1,3-bis(diphenylphosphine)propane (DPPP), 1,4-bis(diphenylphosphine)butane (DPPB), 1,1'-bis(diphenylphosphine)ferrocene (DPPF), 2,2'-bis(diphenylphosphine)-1,1'-binaphthyl (BINAP), 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene (Xantphos), 4,5-bis(diphenylphosphine oxide)-9,9-dimethyloxanthracene (Xantphos bioxide), 4,6-bis(diphenylphosphine)phenoxazine (N-Xantphos), 1,2-bis(di-tert-butylphosphine)benzene (… Combinations of one or more of the following second phosphorus-containing ligands: DTBPMB, 1,1'-bis(di-tert-butylphosphinemethyl)ferrocene, bis(2-diphenylphosphinephenyl) ether (DPEphos), phosphorus-containing ligands containing P,O-hetero-groups, triphenylphosphine, triphenylphosphine oxide, triphenylphosphine mono(sodium m-sulfonate) (TPPMS), triphenylphosphine di(sodium m-sulfonate) (TPPDS), triphenylphosphine tri(sodium m-sulfonate) (TPPTS), tri(2-tert-butylphenyl) phosphite, tri(2,4-di-tert-butylphenyl) phosphite, tri(o-tolyl) phosphite, tri(4-methoxyphenyl) phosphite, triphenylphosphite, trimethylolpropane phosphite, triisopropyl phosphite, tritert-butyl phosphite, triethyl phosphite, diethyl phenyl phosphite, diphenyl phosphite, and bidentate phosphite ligands.

[0039] According to some preferred embodiments, the phosphorus-containing ligand comprises at least one phosphorus-containing ligand containing a P,O-hetero-group and a combination of a second phosphorus-containing ligand selected from tris(2-tert-butylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(o-tolyl) phosphite, tris(4-methoxyphenyl) phosphite, triphenyl phosphite, trimethylolpropane phosphite, triisopropyl phosphite, tris(tert-butyl) phosphite, triethyl phosphite, diethyl phenyl phosphite, diethyl diphenyl phosphite, and bidentate phosphite ligands La-Ld with the following structures.

[0040] According to some more preferred embodiments, the phosphorus-containing ligand comprises at least one phosphorus-containing ligand containing a P,O-hetero-group and a combination of a second phosphorus-containing ligand selected from one or more of tris(2-tert-butylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(o-tolyl) phosphite, tris(4-methoxyphenyl) phosphite, trimethylolpropane phosphite, and 2,2'-bis[(1,1'-biphenyl-2,2'-diyl)phosphite]-3,3'-di-tert-butyl-5,5'-dimethoxy-1,1'-biphenyl (BIPHEPHOS, Ld).

[0041] According to some embodiments, the phosphorus-containing ligand containing the P,O-heteropolymer group has the following structure:

[0042] in,

[0043] X is selected from -CH2-, -C(CH3)2-, -NH-, and the linking bond; R is independently selected from C. 1-6 Alkyl, C 6-18 Aryl, C 1-6 Alkyl-substituted C 6-18 Aryl; Ar is selected from C 6-18 Aryl, preferably phenyl, biphenyl or naphthyl.

[0044] According to some preferred embodiments, the phosphorus-containing ligand containing the P,O-heteromeric group is selected from one or more phosphorus-containing ligands having the following structures:

[0045] According to some preferred embodiments, the phosphorus-containing ligand comprises at least one phosphorus-containing ligand with a P,O-hetero-group selected from L1, L2, L3, L4, L5, L6, DPEphos, Xantphos, and N-Xantphos, and a combination of one or more second phosphorus-containing ligands selected from tris(2-tert-butylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(o-tolyl) phosphite, tris(4-methoxyphenyl) phosphite, triphenyl phosphite, trimethylolpropane phosphite, triisopropyl phosphite, tris(tert-butyl) phosphite, triethyl phosphite, diethyl phenyl phosphite, diphenyl phosphite, and bidentate phosphite ligands La-Ld.

[0046] According to some more preferred embodiments, the phosphorus-containing ligand comprises at least one phosphorus-containing ligand with a P,O-hetero-group selected from L1, L2, L3, L4, L5, L6, DPEphos, Xantphos, and N-Xantphos, and a combination of a second phosphorus-containing ligand selected from one or more of tris(2-tert-butylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(o-tolyl) phosphite, tris(4-methoxyphenyl) phosphite, trimethylolpropane phosphite, and 2,2'-bis[(1,1'-biphenyl-2,2'-diyl)phosphite]-3,3'-di-tert-butyl-5,5'-dimethoxy-1,1'-biphenyl (BIPHEPHOS).

[0047] According to some embodiments, the molar ratio of the phosphorus-containing ligand with the P,O-heteromeric group to the second phosphorus-containing ligand is 1:0.1-10, preferably 1:0.2-5, and more preferably 1:0.5-2. For example, the molar ratio of the phosphorus-containing ligand with the P,O-heteromeric group to the second phosphorus-containing ligand can be 1:0.1, 1:0.2, 1:0.5, 1:0.8, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, 1:10, or any value within any range of two such values.

[0048] According to some embodiments, the palladium compound is selected from one or more of palladium dichloride, bis(acetonitrile)palladium dichloride, palladium acetate, palladium nitrate, palladium trifluoroacetate, bis(triphenylphosphine)palladium dichloride, (1,5-cyclooctadiene)palladium dichloride, allyl palladium chloride, tetra(triphenylphosphine)palladium, bis(acetylacetone)palladium, bis(dibenzylacetone)palladium, and tri(dibenzylacetone)palladium, preferably selected from one or more of palladium acetate, palladium trifluoroacetate, tetra(triphenylphosphine)palladium, bis(acetylacetone)palladium, and tri(dibenzylacetone)palladium.

[0049] According to some embodiments, the acid additive is selected from at least one of organic sulfonic acids, boric acid, benzoic acid, salicylic acid, and Lewis acids containing trifluoromethanesulfonate; the organic sulfonic acids include p-toluenesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, quinoline-8-sulfonic acid, dodecylbenzenesulfonic acid, trifluoromethanesulfonic acid, and methanesulfonic acid; the Lewis acids containing trifluoromethanesulfonate include aluminum trifluoromethanesulfonate, scandium trifluoromethanesulfonate, and bismuth trifluoromethanesulfonate.

[0050] According to some preferred embodiments, the acid additive is selected from at least one of organic sulfonic acids and Lewis acids containing trifluoromethanesulfonate.

[0051] According to some preferred embodiments, the acid additive is selected from one or more of methanesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, quinoline-8-sulfonic acid, trifluoromethanesulfonic acid, aluminum trifluoromethanesulfonate, scandium trifluoromethanesulfonate, and bismuth trifluoromethanesulfonate.

[0052] According to some embodiments, the molar ratio of the total phosphorus-containing ligands to the palladium compound is 1-50:1, preferably 2-5:1. For example, the molar ratio of the total phosphorus-containing ligands to the palladium compound can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, 21:1, 22:1, 23:1, 24:1, 25:1, 26:1, etc. 1, 27:1, 28:1, 29:1, 30:1, 31:1, 32:1, 33:1, 34:1, 35:1, 36:1, 37:1, 38:1, 39:1, 40:1, 41:1, 42:1, 43:1, 44:1, 45:1, 46:1, 47:1, 48:1, 49:1, 50:1, and any value within a range consisting of any two values.

[0053] According to some embodiments, the molar ratio of the acid auxiliary agent to the palladium compound is 1-100:1, preferably 5-20:1. For example, the molar ratio of the acid auxiliary agent to the palladium compound can be 1:1, 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, 95:1, 100:1, or any value within the range of any two values.

[0054] Method for preparing isomeric carboxylic acid esters by hydrogen esterification of highly branched olefins

[0055] In a second aspect, the present invention provides a method for preparing isomeric carboxylic acid esters by hydrogen esterification of highly branched olefins, the method comprising:

[0056] S1. Olefin materials, C 1-4 Fatty alcohols, CO, and catalyst are introduced into a reactor to carry out a hydrogen esterification reaction to obtain a reaction mixture.

[0057] S2. The reaction mixture is subjected to gas-liquid separation to obtain gaseous material and liquid material;

[0058] S3. The liquid phase material is separated to obtain isomeric carboxylic acid esters and a first circulating catalyst.

[0059] According to some embodiments, the catalyst material comprises the catalyst composition according to the first aspect.

[0060] According to some implementation schemes, the catalyst material is fresh catalyst material, recycled catalyst material, or a mixture thereof.

[0061] According to some embodiments, the olefin material contains ≥70% by weight, preferably ≥80% by weight, more preferably ≥90% by weight, and even more preferably ≥95% by weight of highly branched C relative to the total weight of the olefin material. 5-16 Olefins.

[0062] According to some implementation schemes, the high branching degree C 5-16 The olefin is selected from one or more of diisobutylene, triisobutylene, tetraisobutylene, propylene trimer, and propylene tetramer, preferably 2,4,4-trimethyl-1-pentene and / or 2,4,4-trimethyl-2-pentene.

[0063] According to some embodiments, the olefin material is a mixture of highly branched C8 olefins, preferably a mixture of 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene. For example, the olefin material may contain a mixture of 70-80 wt% 2,4,4-trimethyl-1-pentene and 15-30 wt% 2,4,4-trimethyl-2-pentene.

[0064] According to some embodiments, the olefin material is a low-carbon olefin, preferably isobutylene, and is a mixture of products obtained by dimerization or chelation reaction. For example, the olefin material can be a mixture containing highly branched C8 olefins obtained by dimerization or chelation reaction of isobutylene in the presence of an acid catalyst, preferably a mixture containing 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene.

[0065] According to some implementation schemes, the C 1-4 The fatty alcohol is selected from one or more of methanol, ethanol, and isopropanol, with methanol being preferred.

[0066] According to some implementation schemes, in step S1, the molar ratio of the palladium compound to the highly branched olefin in the catalyst material is 1:20-20000, preferably 1:50-10000, more preferably 1:80-5000, and even more preferably 1:100-1000. For example, the molar ratio of palladium compound to highly branched olefin in the catalyst material can be 1:20, 1:50, 1:80, 1:100, 1:150, 1:200, 1:300, 1:400, 1:500, 1:800, 1:1000, 1:2000, 1:3000, 1:4000, 1:5000, 1:6000, 1:7000, 1:8000, 1:9000, 1:10000, 1:12000, 1:15000, 1:18000, 1:20000, or any value within any range of two such values.

[0067] According to some implementation schemes, in step S1, the highly branched olefin reacts with the C 1-4 The molar ratio of fatty alcohols is 1:1-20, preferably 1:2-12, and more preferably 1:3-6. For example, the molar ratio of palladium compound to highly branched olefin in the catalyst material can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, or any value within any range of any two values.

[0068] According to some implementation schemes, in step S1, the temperature of the hydrogen esterification reaction is 60℃-250℃, preferably 90℃-200℃, more preferably 100℃-160℃, and even more preferably 100℃-140℃.

[0069] According to some implementation schemes, in step S1, the pressure of the hydrogen esterification reaction is 1 MPa-12 MPa, preferably 2 MPa-10 MPa, and more preferably 5 MPa-8 MPa.

[0070] According to some implementation schemes, in step S1, the hydrogen esterification reaction takes 1-40 hours, preferably 3-20 hours, and more preferably 5-15 hours.

[0071] According to some implementation schemes, in step S2, the gaseous material is recycled back to step S1 as a circulating CO material, preferably after condensation and / or absorption, and then recycled back to step S1.

[0072] According to some implementation schemes, in step S2, the gas-liquid separation can be carried out in a gas-liquid separation tank under conditions of cooling without pressure reduction. The temperature of the gas-liquid separation can be 0℃-100℃, preferably 20℃-80℃, and more preferably 20℃-40℃.

[0073] According to some implementation schemes, in step S3, the separation process includes a de-alcoholization process and a deesterification process.

[0074] According to some embodiments, the conditions for the alcohol removal process are controlled such that the alcohol content in the liquid phase material before the alcohol removal process is less than 0.1 wt%, for example less than 0.05 wt% or less than 0.01 wt%.

[0075] According to some implementation schemes, in step S3, the liquid phase material is subjected to de-alcoholization treatment to obtain alcohol material and mixture material, the alcohol material is recycled to step S1, and the mixture material is subjected to deesterification treatment to obtain isomeric carboxylic acid ester and first circulating catalyst.

[0076] According to some preferred embodiments, the dealcoholization process includes, but is not limited to, atmospheric distillation. The deesterification process includes a phase separation process and / or vacuum distillation. The phase separation process includes separating isomeric carboxylic esters and the first recycled catalyst material after settling.

[0077] According to some preferred embodiments, the alcohol removal process and the deesterification process are carried out under normal pressure.

[0078] According to some embodiments, the method further includes step S4: purifying the isocarboxylic acid ester obtained in step S3 to obtain the purified isocarboxylic acid ester and an optional second circulating catalyst.

[0079] According to some preferred embodiments, the refining process includes distillation and / or rectification.

[0080] According to some embodiments, atmospheric or vacuum distillation or rectification can be employed, and the distillation or rectification separation device can be a vacuum or atmospheric pressure distillation kettle, a rectification column, or a thin-film evaporator, or other distillation separation devices known in the art. In one embodiment, the pressure of the vacuum distillation kettle or rectification column is ≤10. -2 MPa, for example ≤10 -3 MPa, for example ≤10 -4 MPa; column bottom temperature can be 70-200℃; thin film evaporator pressure ≤10mmHg, for example ≤6mmHg, for example ≤1mmHg; heating surface temperature can be 35-150℃, for example 40-100℃, for example 45-70℃; residence time can be 1-30 minutes, for example 1-10 minutes, for example 1-2 minutes. If a distillation column is used, the reflux ratio can be 1-20:1, for example 1-10:1.

[0081] According to some embodiments, the method further includes step S5: recycling the first circulating catalyst or the first circulating catalyst and the second circulating catalyst to step S1, optionally adding ligands and / or acid promoters to carry out a hydrogen esterification reaction.

[0082] According to some preferred embodiments, the molar ratio of the supplemented ligand to the initially added ligand is 0.01-200:100, preferably 0.1-100:100, and more preferably 1-50:100. For example, the molar ratio of the supplemented ligand to the initially added ligand can be 0.01:100, 0.02:100, 0.03:100, 0.04:100, 0.05:100, 0.06:100, 0.07:100, 0.08:100, 0.09:100, 0.1:100, 0.2:100, 0.5:100, 0.8:100, 1: 100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, 20:100, 50:100, 80:100, 100:100, 120:100, 150:100, 180:100, 200:100, and any value within a range of any two values.

[0083] According to some preferred embodiments, the molar ratio of the supplemented acid additive to the initially added acid additive is 0.01-200:100, preferably 0.1-150:100, and more preferably 1-100:100. For example, the molar ratio of the supplemented acid additive to the initially added acid additive can be 0.01:100, 0.02:100, 0.03:100, 0.04:100, 0.05:100, 0.06:100, 0.07:100, 0.08:100, 0.09:100, 0.1:100, 0.2:100, 0.5:100, 0.8:100, 1... :100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, 20:100, 50:100, 80:100, 100:100, 120:100, 150:100, 180:100, 200:100, and any value within the range of any two values.

[0084] According to some preferred embodiments, the method includes:

[0085] S1. Olefin materials, C 1-4 Fatty alcohols, CO, and catalyst are introduced into a reactor to carry out a hydrogen esterification reaction to obtain a reaction mixture.

[0086] S2. The reaction mixture is subjected to gas-liquid separation to obtain gaseous material and liquid material. Optionally, the gaseous material is recycled as recycled CO material to step S1.

[0087] S3. The liquid phase material is subjected to alcohol removal treatment to obtain alcohol material and mixture material. Optionally, the alcohol material is recycled to step S1, and the mixture material is subjected to deesterification treatment to obtain isomeric carboxylic acid ester and first circulating catalyst.

[0088] S4. Optionally, the isocarboxylic acid ester obtained in step S3 is purified to obtain the purified isocarboxylic acid ester and, optionally, a second circulating catalyst.

[0089] S5. Recycle the first circulating catalyst or the first circulating catalyst and the second circulating catalyst to step S1, optionally adding ligands and / or acid auxiliaries, for the next hydrogen esterification reaction.

[0090] Application of hydrogen esterification catalysts

[0091] In a third aspect, the present invention provides the use of the catalyst composition according to the first aspect in a hydrogen esterification reaction, preferably in the preparation of isomeric carboxylic acid esters by hydrogen esterification of highly branched olefins, and particularly in the preparation of methyl isononanoate by hydrogen esterification of highly branched C8 olefins.

[0092] System for preparing isomeric carboxylic acid esters by hydrogen esterification of highly branched olefins

[0093] In a fourth aspect, the present invention provides a system for the hydrogen esterification of highly branched olefins to prepare isomeric carboxylic acid esters, particularly a system for the method of preparing isomeric carboxylic acid esters by hydrogen esterification of highly branched olefins according to the second aspect, comprising a hydrogen esterification reaction unit I, a gas-liquid separation unit II, a separation and processing unit III, and optionally a catalyst regeneration unit IV.

[0094] According to some implementation schemes, the inlet of the hydrogen esterification reaction unit I is connected to the CO feed line 1, the alcohol feed line 2, the catalyst feed line 3, and the olefin feed line 4. The outlet of the hydrogen esterification reaction unit I is connected to the inlet of the gas-liquid separation unit II via a connecting line 8. The catalyst feed line 3 is connected to the palladium feed line 5, the acid feed line 6, and the ligand feed line 7. The ligand feed line 7 includes a first ligand feed line 7-i and a second ligand feed line 7-ii.

[0095] According to some embodiments, the hydrogen esterification reaction unit I includes at least one reactor, such as, but not limited to, a batch reactor, a tubular reactor, or a combination thereof.

[0096] According to some embodiments, the hydrogen esterification reaction unit I comprises at least two reactors connected in series. The reaction temperatures of the two reactors can be the same, lower at the beginning and higher at the end, or higher at the beginning and lower at the end. According to some embodiments, reducing the residence time of the material in the high-temperature reaction zone helps to reduce catalyst decomposition.

[0097] According to some implementation schemes, CO material can be introduced from the bottom of one reactor or from the bottom of multiple reactors.

[0098] According to some implementation schemes, the ratio of CO to highly branched olefins introduced into different reactors can be the same or different. The ratio of CO to highly branched olefins in each reactor can be adjusted to an optimal value, which is beneficial for improving conversion rate and selectivity.

[0099] According to some implementation schemes, when a tubular reactor is used, CO, alcohol, and catalyst are introduced from the bottom of the tubular reactor, and the reaction mixture is removed from the top of the tubular reactor.

[0100] According to some implementation schemes, when a tubular reactor is used, CO, alcohol, and catalyst are introduced from the top of the tubular reactor, and the reaction mixture is removed from the bottom of the tubular reactor.

[0101] According to some implementation schemes, the gas-liquid separation unit II has a gas phase outlet and a liquid phase outlet. The gas phase outlet is connected to the CO feed line 2 via the CO circulation line 9, and the liquid phase outlet is connected to the inlet of the separation and processing unit III via the connecting line 10.

[0102] According to some implementation schemes, the gas-liquid separation unit II includes, but is not limited to, at least one liquid separator or flash tank.

[0103] According to some implementation schemes, the separation processing unit III includes a de-alcoholization unit III-1 and a deesterification unit III-2.

[0104] According to some implementation schemes, the liquid phase outlet of the gas-liquid separation unit II is connected to the inlet of the de-alcoholization unit III-1 via a connecting line 10.

[0105] According to some embodiments, the dealcoholization unit III-1 has an alcohol feed outlet and a mixture outlet. The alcohol feed outlet is connected to the alcohol feed line 2 via an alcohol circulation line 11. The mixture outlet is connected to the inlet of the deesterification unit III-2 via a connecting line 12.

[0106] According to some embodiments, the deesterification unit III-2 has an ester material outlet 13 and a catalyst material outlet. The catalyst material outlet is connected to the catalyst material feed line 3 via a catalyst circulation line 14 and to the inlet of the catalyst regeneration unit IV via a connecting line 15. The inlet of the catalyst regeneration unit IV is also connected to an acid material line 6 and a ligand material line 7. The ligand material line 7 includes a first ligand material line 7-i and a second ligand material line 7-ii. The outlet of the catalyst regeneration unit is connected to the catalyst material feed line 3 via a catalyst circulation line 16.

[0107] The present invention also discloses the following embodiments.

[0108] Scheme 1. A catalyst, said catalyst being composed of a palladium compound, a phosphorus-containing ligand, and an acid promoter; wherein the molar ratio of the phosphorus-containing ligand to the palladium compound (P / Pd) is 1–50:1; and the molar ratio of the acid promoter to the palladium compound is 1–100:1;

[0109] The palladium compound is selected from one of palladium dichloride, bis(acetonitrile)palladium dichloride, palladium acetate, palladium nitrate, palladium trifluoroacetate, bis(triphenylphosphine)palladium dichloride, (1,5-cyclooctadiene)palladium dichloride, allyl palladium chloride, tetra(triphenylphosphine)palladium, di(acetylacetone)palladium, bis(dibenzylacetone)palladium, and tri(dibenzylacetone)palladium.

[0110] The phosphorus-containing ligand is selected from 1,2-bis(diphenylphosphine)ethane, 1,3-bis(diphenylphosphine)propane, 1,4-bis(diphenylphosphine)butane, 1,1'-bis(diphenylphosphine)ferrocene, 2,2'-bis(diphenylphosphine)-1,1'-binaphthyl, 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, 4,5-bis(diphenylphosphine oxide)-9,9-dimethyloxanthracene, and 4,6-bis(diphenylphosphine)phenoxane. Azine, 1,2-bis(di-tert-butylphosphine)benzene, 1,1'-bis(di-tert-butylphosphine)ferrocene, tris(2,4-di-tert-butylphenyl)phosphite, trimethylolpropane phosphite, 2,2'-bis[(1,1'-biphenyl-2,2'-diyl)phosphite]-3,3'-di-tert-butyl-5,5'-dimethoxy-1,1'-biphenyl and one or more combinations of phosphorus-containing ligands containing P,O-hetero-groups;

[0111] The acid additive is one or more combinations of organic sulfonic acids, boric acid, benzoic acid, salicylic acid, and Lewis acids containing trifluoromethanesulfonate; the organic sulfonic acids include p-toluenesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, quinoline-8-sulfonic acid, dodecylbenzenesulfonic acid, trifluoromethanesulfonic acid, and methanesulfonic acid; the Lewis acids containing trifluoromethanesulfonate include aluminum trifluoromethanesulfonate, scandium trifluoromethanesulfonate, and bismuth trifluoromethanesulfonate.

[0112] Option 2. The application of the catalyst described in Option 1 in the carbonylation and esterification of diisobutylene to prepare methyl isononanoate, characterized in that it specifically includes:

[0113] The catalyst, composed of palladium compound, phosphorus-containing ligand, and acid auxiliary agent, diisobutylene, and methanol were added to a stainless steel high-pressure reactor. After sealing the reactor, the atmosphere inside was replaced three times with CO gas. Then, CO gas at 3-6 MPa was introduced, and the reaction was carried out at 90-150°C for 3-24 hours. After the reaction was completed, the reaction solution was cooled to room temperature and gas chromatographic analysis was performed. Hexadecane was used as an internal standard to calculate the conversion rate of diisobutylene and the chromatographic yield of methyl isononanoate. The reaction solution was then subjected to vacuum distillation to separate the methyl isononanoate product and the catalyst. The molar ratio of palladium compound to diisobutylene was 1:50-20000; the molar ratio of diisobutylene to methanol was 1:1-10; the P / Pd molar ratio of phosphorus-containing ligand to palladium compound in the catalyst was 1-50:1, and the molar ratio of acid auxiliary agent to palladium compound was 1-100:1.

[0114] To facilitate understanding of the present invention, the following embodiments are provided. However, these embodiments are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0115] Example

[0116] The present invention will be described in detail below through embodiments. Unless otherwise specified, all raw materials used in the following embodiments are commercially available.

[0117] In the following examples and comparative examples, the olefin feedstock was a commercially available C8 olefin with the following composition: 75.1 wt% 2,4,4-trimethyl-1-pentene, 21.2 wt% 2,4,4-trimethyl-2-pentene, and the balance being other multi-branched olefins.

[0118] In the following examples and comparative examples, the hydrogen esterification reactor used was a single batch reactor.

[0119] In the following examples and comparative examples, the chemical reagents used were purchased from Shanghai Aladdin Chemical Reagent Co., Ltd., Shanghai McLean Biochemical Co., Ltd., and Alfaisa China Co., Ltd., and could be used directly without further purification. The solvents were dried and distilled before use.

[0120] In the following examples and comparative examples, the ligands used were commercially available or synthesized according to existing techniques. Synthetic methods are described in the Journal of Catalysis (2023), 426, 214-221; and the Journal of Molecular Structure (2025), 1336, 1421-27.

[0121] In the following examples and comparative examples, the yield of the product methyl isononanoate was determined by Anglient-7890 gas chromatography (HP-PONA 50m × 0.2mm capillary column) equipped with a high-pressure sampler, and calculated using n-hexadecane as an internal standard. The yields were calculated individually for each reaction procedure (initial reaction or cyclic reaction).

[0122] The catalyst single-pass lifetime is calculated as follows: when the yield of methyl isononanoate decreases to about 80%, the catalyst is considered to have begun to be significantly deactivated, and the number of reactions the catalyst undergoes is the catalyst single-pass lifetime.

[0123] Example 1 (Initial Reaction)

[0124] Examples I-1 to 27 and Comparative Examples I-1 to 32

[0125] 0.2 mmol of palladium compound, 0.6 mmol of phosphorus-containing ligand (or 0.3 mmol each of two phosphorus-containing ligands, i.e., phosphorus-containing ligand 1 and phosphorus-containing ligand 2 with P,O- heterogroups), 3 mmol of acid auxiliaries, 100 mmol of diisobutylene, and 500 mmol of methanol were added to a stainless steel autoclave. After ensuring the airtightness of the apparatus, the atmosphere inside the autoclave was purged with CO gas three times, and then CO was introduced to 6.0 MPa. The reaction mixture was heated to 130 °C and reacted for 10 hours to obtain the reaction mixture. The reaction mixture was cooled to room temperature, and a sample was taken for gas chromatography analysis. The yield of methyl isononanoate was calculated using n-hexadecane as an internal standard.

[0126] The composition of the catalysts used in Examples (Ex.) I-1 to 27 and Comparative Examples (CE.) I-1 to 32 and the yield of methyl isononanoate in the first reaction are shown in Table 1.

[0127] Table 1. Initial reaction results of diisobutene hydrogen esterification to prepare methyl isononanoate using different catalysts

[0128] Note: BIPHEPHOS: 2,2'-bis[(1,1'-biphenyl-2,2'-diyl)phosphite]-3,3'-di-tert-butyl-5,5'-dimethoxy-1,1'-biphenyl; DPPE: 1,2-bis(diphenylphosphine)ethane; DPPP: 1,3-bis(diphenylphosphine)propane; DPPB: 1,4-bis(diphenylphosphine)butane; DPPF: 1,1'-bis(diphenylphosphine)ferrocene; BINAP: 2,2'-bis(diphenylphosphine)-1,1'-binaphthyl; Xantphos: 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene; N-Xantphos: 4,6-bis(diphenylphosphine)phenoxazine; DPEphos: bis(2-diphenylphosphinephenyl) ether; TPPMS: triphenylphosphine mono(sodium m-sulfonate); TPPTS: triphenylphosphine tri(sodium m-sulfonate).

[0129] Examples I-28 to 32

[0130] The method was carried out according to Examples I-Ex.1, except that the molar amounts of L2, tris(2,4-di-tert-butylphenyl) phosphite, and benzenesulfonic acid in the catalyst were adjusted, as shown in Table 2. The yields of methyl isononanoate in the first reactions of Examples I-28–32 are shown in Table 2.

[0131] Table 2. Effect of the molar amounts of L2, tris(2,4-di-tert-butylphenyl) phosphite, and benzenesulfonic acid in the catalyst on the diisobutylene hydrogen esterification reaction.

[0132] Example II (Cyclic Reaction)

[0133] Example II-1

[0134] (1) 0.2 mmol palladium acetate, 0.3 mmol L2 ligand, 0.3 mmol tris(2,4-di-tert-butylphenyl) phosphite, 3 mmol benzenesulfonic acid, 100 mmol diisobutylene, and 500 mmol methanol were added to a stainless steel autoclave. After ensuring the airtightness of the apparatus, the atmosphere inside the autoclave was purged with CO gas three times, and then CO was introduced to 6.0 MPa. The reaction mixture was heated to 130 °C and reacted for 10 hours to obtain the reaction mixture. A sample was taken for gas chromatography analysis, and the yield of methyl isononanoate was calculated using n-hexadecane as an internal standard.

[0135] (2) Separate the reaction mixture into gas and liquid phases to obtain CO-containing gaseous and liquid phases, and recycle the CO-containing gaseous phase.

[0136] (3) Methanol is separated from the liquid material by atmospheric pressure distillation, and then methyl isononanoate is separated by sedimentation and stratification.

[0137] (4) The remaining liquid phase material is recycled as a circulating catalyst to replace the fresh catalyst in step (1) for hydrogen esterification reaction with diisobutylene and methanol. Steps (1)-(4) are repeated for recycling. During the recycling process, when the yield of methyl isononanoate drops to about 80% (for example, after the 10th, 20th, 30th and 40th reactions), 0.1 mmol L2 ligand, 0.1 mmol tris(2,4-di-tert-butylphenyl) phosphite and 0.1 mmol benzenesulfonic acid are added to the circulating catalyst before the next round of recycling.

[0138] The yield of methyl isononanoate after 50 cycles using a catalyst comprising an L2 ligand and a tris(2,4-di-tert-butylphenyl) phosphite ligand combination is shown in Figure 1. As shown in Figure 1, the catalyst maintains good activity after 50 cycles in the preparation of methyl isononanoate via the hydrogen esterification of diisobutylene, indicating its excellent cycling stability and easy regeneration by adding ligands and acid promoters.

[0139] Example II-2

[0140] The method was carried out according to Example II-1, except that in step (4), during the cyclic process, when the yield of methyl isononanoate dropped to below about 80% (e.g., after the 10th and 17th reactions), only phosphorus-containing ligands (0.1 mmol L2 and 0.1 mmol tris(2,4-di-tert-butylphenyl)phosphite) were added without adding acid auxiliaries.

[0141] The yield of methyl isononanoate after 21 cycles of addition of only phosphorus-containing ligands without acid promoters is shown in Figure 2. This example demonstrates that even during cycling, the catalyst activity can be significantly restored by adding only phosphorus-containing ligands without acid promoters, achieving a 93% methyl isononanoate yield after the 10th cycle. The catalyst maintains good activity after 20 cycles.

[0142] Example II-3

[0143] The procedure was carried out according to Example II-1, except that the combination of 0.3 mmol L2 ligand and 0.3 mmol tris(2,4-di-tert-butylphenyl) phosphite was used instead of the combination of 0.3 mmol Xantphos ligand and 0.3 mmol tris(2,4-di-tert-butylphenyl) phosphite.

[0144] The yields of methyl isononanoate after 19 cycles using a catalyst comprising Xantphos ligand and tris(2,4-di-tert-butylphenyl) phosphite are shown in Figure 3. As shown in Figure 3, the catalyst maintained good activity after 19 cycles in the diisobutylene hydroesterification reaction to prepare methyl isononanoate, indicating its excellent cycling stability. When the yield of methyl isononanoate decreased from 98% in the first reaction to 79% after the 10th reaction, by adding 0.1 mmol of Xantphos ligand, 0.1 mmol of tris(2,4-di-tert-butylphenyl) phosphite, and 0.1 mmol of benzenesulfonic acid, the yields of methyl isononanoate in the 11th-20th reactions were still 98%-83%, indicating that the catalyst can be easily regenerated by adding ligands and acid promoters.

[0145] Example II-4

[0146] The procedure was carried out according to Example II-1, except that the combination of 0.3 mmol L2 ligand and 0.3 mmol tris(2,4-di-tert-butylphenyl) phosphite was replaced with a combination of 0.3 mmol L2 ligand and 0.3 mmol BIPHEPHOS ligand.

[0147] The yields of methyl isononanoate after 14 cycles using a catalyst containing a combination of L2 and BIPHEPHOS ligands are shown in Figure 4. As shown in Figure 4, the catalyst maintained good activity after 14 cycles in the preparation of methyl isononanoate via the hydrogen esterification of diisobutylene. When the yield of methyl isononanoate decreased from 96% in the first reaction to 80% after the 7th reaction, the addition of 0.1 mmol L2, 0.1 mmol BIPHEPHOS, and 0.1 mmol benzenesulfonic acid resulted in methyl isononanoate yields of 93%–82% in the 8th–15th reactions, indicating that the catalyst can be easily regenerated by adding ligands and acid promoters.

[0148] Comparative Example II-1

[0149] The procedure was carried out according to Example II-1, except that the combination of 0.3 mmol L2 ligand and 0.3 mmol tris(2,4-di-tert-butylphenyl) phosphite was replaced with 0.6 mmol L2 ligand.

[0150] The yields of methyl isononanoate using a catalyst containing only L2 as the phosphorus-containing ligand in five cycles are shown in Figure 5. After the fifth hydrogen esterification reaction, the yield of methyl isononanoate decreased from 95% in the first reaction to 68%, and palladium black precipitate gradually formed in the reaction solution. In the sixth hydrogen esterification reaction, even with the addition of 0.2 mmol of L2 ligand and 0.1 mmol of benzenesulfonic acid, the catalyst activity could not be restored, and the yield of methyl isononanoate decreased to 64%, indicating that the catalyst has poor stability and its activity could not be restored even with the addition of ligand and acid promoter.

[0151] Comparative Example II-2

[0152] The procedure was carried out according to Example II-1, except that the combination of 0.3 mmol L2 ligand and 0.3 mmol tris(2,4-di-tert-butylphenyl) phosphite ligand was replaced with 0.6 mmol tris(2,4-di-tert-butylphenyl) phosphite ligand.

[0153] The yields of methyl isononanoate using a catalyst containing only tris(2,4-di-tert-butylphenyl) phosphite as a phosphorus-containing ligand in two cycles are shown in Figure 6. After the first hydrogenation reaction, a large amount of palladium black precipitate formed in the reaction solution. In the second hydrogenation reaction, the yield of methyl isononanoate decreased from 90% in the first reaction to 1%. Even with the addition of 0.2 mmol of tris(2,4-di-tert-butylphenyl) phosphite ligand and 0.1 mmol of benzenesulfonic acid, the catalyst activity could not be recovered in the third hydrogenation reaction, with a methyl isononanoate yield of <2%, indicating that the catalyst has very poor stability.

[0154] Comparative Example II-3

[0155] The procedure was carried out according to Example II-1, except that the combination of 0.3 mmol L2 ligand and 0.3 mmol triphenylphosphine ligand was used instead of the combination of 0.3 mmol L2 ligand and 0.3 mmol tri(2,4-di-tert-butylphenyl) phosphite.

[0156] The yields of methyl isononanoate using a catalyst containing a combination of L2 and triphenylphosphine as phosphorus-containing ligands in six cycles are shown in Figure 7. This catalyst exhibits low catalytic activity in the hydrogen esterification of diisobutylene to prepare methyl isononanoate. The methyl isononanoate yield decreased from 83% in the first reaction to 45% after the sixth reaction. After the addition of 0.1 mmol L2, 0.1 mmol triphenylphosphine, and 0.1 mmol benzenesulfonic acid, the seventh reaction yielded 43% methyl isononanoate, indicating that the catalyst activity cannot be restored by adding ligands and acid promoters.

[0157] Example III (Different C8 Olefins)

[0158] The reaction was carried out according to the method of Examples I-Ex.1, except that the C8 olefins shown in Table 3 were used, and the reaction results are shown in Table 2. As shown in Table 2, the catalyst of the present invention has specific catalytic activity for highly branched C8 olefins.

[0159] Table 3. Results of the hydrogen esterification of different C8H6 olefins to prepare methyl isononanoate using catalysts composed of palladium acetate, L2, tris(2,4-di-tert-butylphenyl) phosphite and benzenesulfonic acid.

[0160] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A catalyst composition, characterized in that, The catalyst composition comprises a palladium compound, a phosphorus-containing ligand, and an acid promoter. The phosphorus-containing ligand comprises at least one phosphorus-containing ligand containing a P,O-hetero-group and a combination of a second phosphorus-containing ligand selected from tris(2-tert-butylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(o-tolyl) phosphite, tris(4-methoxyphenyl) phosphite, triphenyl phosphite, trimethylolpropane phosphite, triisopropyl phosphite, tris(tert-butyl) phosphite, triethyl phosphite, diethyl phenyl phosphite, diphenyl phosphite, and bidentate phosphite ligands La-Ld with the following structures.

2. The catalyst composition according to claim 1, characterized in that, The phosphorus-containing ligand comprises at least one phosphorus-containing ligand containing a P,O-hetero-group and a combination of a second phosphorus-containing ligand selected from one or more of tris(2-tert-butylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(o-tolyl) phosphite, tris(4-methoxyphenyl) phosphite, trimethylolpropane phosphite, and 2,2'-bis[(1,1'-biphenyl-2,2'-diyl)phosphite]-3,3'-di-tert-butyl-5,5'-dimethoxy-1,1'-biphenyl (BIPHEPHOS).

3. The catalyst composition according to claim 1 or 2, characterized in that, The phosphorus-containing ligand containing the P,O-heteropolymer group has the following structure: in, X is selected from -CH2-, -C(CH3)2-, -NH-, and the linking bond; R is independently selected from C. 1-6 Alkyl, C 6-18 Aryl, C 1-6 Alkyl-substituted C 6-18 Aryl; Ar is selected from C 6-18 Aryl, preferably phenyl, biphenyl or naphthyl; Preferably, the phosphorus-containing ligand containing the P,O-heteromeric group is selected from one or more phosphorus-containing ligands having the following structures:

4. The catalyst composition according to any one of the preceding claims, characterized in that, The molar ratio of the phosphorus-containing ligand containing the P,O- heterogroup to the second phosphorus-containing ligand is 1:0.1-10, preferably 1:0.2-5.

5. The catalyst composition according to any one of the preceding claims, wherein the palladium compound is selected from one or more of palladium dichloride, bis(acetonitrile)palladium dichloride, palladium acetate, palladium nitrate, palladium trifluoroacetate, bis(triphenylphosphine)palladium dichloride, (1,5-cyclooctadiene)palladium dichloride, allyl palladium chloride, tetra(triphenylphosphine)palladium, bis(acetylacetone)palladium, bis(dibenzylacetone)palladium, and tri(dibenzylacetone)palladium, preferably selected from one or more of palladium acetate, palladium trifluoroacetate, tetra(triphenylphosphine)palladium, bis(acetylacetone)palladium, and tri(dibenzylacetone)palladium.

6. The catalyst composition according to any one of the preceding claims, wherein the acid promoter is selected from one or more of p-toluenesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, quinoline-8-sulfonic acid, dodecylbenzenesulfonic acid, trifluoromethanesulfonic acid, methanesulfonic acid, boric acid, benzoic acid, salicylic acid, aluminum trifluoromethanesulfonate, scandium trifluoromethanesulfonate, and bismuth trifluoromethanesulfonate, more preferably one or more of methanesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, quinoline-8-sulfonic acid, trifluoromethanesulfonic acid, aluminum trifluoromethanesulfonate, scandium trifluoromethanesulfonate, and bismuth trifluoromethanesulfonate.

7. The catalyst composition according to any one of the preceding claims, wherein the total molar ratio of the phosphorus-containing ligands to the palladium compound is 1-50:1, preferably 2-5:1; and / or the molar ratio of the acid promoter to the palladium compound is 1-100:1, preferably 5-20:

1.

8. A method for preparing isomeric carboxylic acid esters by hydrogen esterification of highly branched olefins, characterized in that, The method includes: S1. Olefin materials, C 1-4 Fatty alcohols, CO, and catalyst are introduced into a reactor to carry out a hydrogen esterification reaction to obtain a reaction mixture. S2. The reaction mixture is subjected to gas-liquid separation to obtain gaseous material and liquid material; S3. The liquid phase material is separated to obtain isomeric carboxylic acid esters and a first circulating catalyst; In step S1, the catalyst material comprises the catalyst composition according to any one of claims 1-7; The olefin material contains ≥70% by weight of highly branched C relative to the total weight of the olefin material. 5-16 Olefins.

9. The method according to claim 8, characterized in that, In step S1, the molar ratio of the palladium compound to the highly branched olefin in the catalyst material is 1:20-20000, preferably 1:50-10000, more preferably 1:80-5000, and even more preferably 1:100-1000; and / or The highly branched olefin and the C 1-4 The molar ratio of fatty alcohols is 1:1-20, preferably 1:2-12, and more preferably 1:3-6.

10. The method according to claim 8 or 9, characterized in that, In step S1, the temperature of the hydrogen esterification reaction is 60℃-250℃, preferably 90℃-200℃, more preferably 100℃-160℃; and / or The pressure of the hydrogen esterification reaction is 1 MPa-12 MPa, preferably 2 MPa-10 MPa, more preferably 5 MPa-8 MPa; and / or The hydrogen esterification reaction takes 1-40 hours, preferably 3-20 hours, and more preferably 5-15 hours.

11. The method according to any one of claims 8-10, characterized in that, In step S3, the separation process includes a dealcoholization process and a deesterification process; Preferably, the conditions for the alcohol removal treatment are controlled such that the alcohol content in the liquid phase material is less than 0.1 wt% before the deesterification treatment is performed; Preferably, the dealcoholization process includes atmospheric distillation; the deesterification process includes stratification and / or vacuum distillation.

12. The method according to any one of claims 8-11, characterized in that, The method further includes step S4: purifying the isocarboxylic acid ester obtained in step S3 to obtain the purified isocarboxylic acid ester and an optional second-cycle catalyst. Preferably, the refining process includes distillation and / or rectification.

13. The method according to any one of claims 8-12, characterized in that, The method further includes step S5: recycling the first circulating catalyst or the first circulating catalyst and the second circulating catalyst to step S1, optionally adding ligands and / or acid auxiliaries to carry out the hydrogen esterification reaction; Preferably, the molar ratio of the supplemented ligand to the initially added ligand is 0.01-200:100, more preferably 0.1-100:100, and even more preferably 1-50:100; Preferably, the molar ratio of the supplemented acid additive to the initially added acid additive is 0.01-200:100, more preferably 0.1-150:100, and even more preferably 1-100:

100.

14. The method according to any one of claims 8-13, characterized in that, The C 1-4 Fatty alcohols are selected from one or more of methanol, ethanol, and isopropanol; and / or The highly branched C 5-16 The olefin is selected from one or more of diisobutylene, triisobutylene, tetraisobutylene, propylene trimer, and propylene tetramer, preferably 2,4,4-trimethyl-1-pentene and / or 2,4,4-trimethyl-2-pentene.

15. A system for the hydrogen esterification of highly branched olefins to prepare isomeric carboxylic acid esters, comprising a hydrogen esterification reaction unit, a gas-liquid separation unit, a separation and processing unit, and optionally a catalyst regeneration unit. The inlet of the hydrogen esterification reaction unit is connected to the CO feed line, the alcohol feed line, the catalyst feed line, and the olefin feed line, and the outlet of the hydrogen esterification reaction unit is connected to the inlet of the gas-liquid separation unit. The gas-liquid separation unit has a gas phase outlet and a liquid phase outlet. The liquid phase outlet is connected to the inlet of the separation and processing unit. Preferably, the gas phase outlet is connected to the CO feed pipeline via a CO circulation pipeline. The separation and processing unit includes a de-alcoholization unit and a de-esterification unit. The liquid phase outlet of the gas-liquid separation unit is connected to the inlet of the de-alcoholization unit. The de-alcoholization unit has an alcohol material outlet and a mixed material outlet. The mixed material outlet is connected to the inlet of the de-esterification unit. Preferably, the alcohol material outlet is connected to the alcohol feed pipeline via an alcohol circulation pipeline. The deesterification unit has an ester material outlet and a catalyst material outlet. The catalyst material outlet is connected to the catalyst material feed pipeline via a catalyst circulation pipeline and to the inlet of the catalyst regeneration unit IV via a connecting pipeline. The outlet of the catalyst regeneration unit is connected to the catalyst material feed pipeline via a catalyst circulation pipeline.

16. Use of the catalyst composition according to any one of claims 1-7 for catalyzing the hydrogen esterification reaction of highly branched olefins.

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