A diphosphine ligand modified rhodium catalyst, its preparation method and application

Abstract

The application provides a kind of phosphine ligand modified rhodium catalyst and its preparation method and application, it is related to catalyst technical field.Dual phosphine ligand modified rhodium catalyst includes active metal component and the dual phosphine ligand of oxidation resistance modification treatment, active metal component is Rh, dual phosphine ligand is one or more of 2,2'-bis (diphenyl phosphine) biphenyl, 1,1'-binaphthalene-2,2'-bisdiphenylphosphine, 4,5-bis (diphenyl phosphine) -9,9-dimethyl xanthene or (S)-DTBM-SEGPHOS.By selecting big steric hindrance dual phosphine ligand, the generation of side reaction is inhibited by steric hindrance, and the selectivity of ethanol aldehyde is improved, and by stereo effect, the coordination configuration of formaldehyde and CO is limited, the linear insertion of C-C bond is promoted to generate ethanol aldehyde, and the dual phosphine ligand of oxidation resistance modification treatment can further enhance the oxidation resistance of ligand skeleton, and improve thermal stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a biphosphine ligand modified rhodium catalyst and a preparation method and application thereof. BACKGROUND

[0002] Glycolaldehyde (HOCH2CHO) is an important chemical raw material, which is widely used in pharmaceutical, perfume and bio-based material fields. It reacts with acrolein to generate ribose, which is a very important molecule in the origin of life. Glycolaldehyde can also be hydrogenated to produce important chemical raw material ethylene glycol. In the food industry, glycolaldehyde can play a good effect as a browning agent, and is an excellent browning initiator for food dyeing, condiments, essences and the like.

[0003] Formaldehyde hydroformylation reaction is an important way to produce glycolaldehyde, and is also an important intermediate step of syngas direct synthesis of ethylene glycol. The formaldehyde hydroformylation catalysts reported at present are mainly Co-based, Ru-based and Rh-based homogeneous catalysts. Among them, Rh catalyst is widely studied due to its best activity. In 1977, Monsanto Company reported in the patent EP0002908A that the use of bis(triphenylphosphine)carbonyl rhodium chloride can realize formaldehyde hydroformylation under relatively mild conditions.

[0004] The existing biphosphine ligand modified rhodium catalysts have the problems of poor thermal stability and poor selectivity. At high temperature (for example, more than 150℃), the existing biphosphine ligand is easy to be oxidized or decomposed, and is easy to generate by-products (ethylene glycol, formic acid, polyformaldehyde, etc.), resulting in rhodium metal agglomeration and deactivation. Therefore, it is necessary to develop a formaldehyde hydroformylation catalyst with high thermal stability and high selectivity. SUMMARY

[0005] In order to solve the above problems, the present application provides a biphosphine ligand modified rhodium catalyst, which solves the problems of poor thermal stability and poor selectivity of the existing formaldehyde hydroformylation catalyst.

[0006] The first aspect of the present application provides a biphosphine ligand modified rhodium catalyst, which comprises an active metal component and an antioxidant modified biphosphine ligand. The active metal component is Rh, and the biphosphine ligand is one or more of 2,2'-bis(diphenylphosphino) biphenyl (abbreviated as BIPHEP), 1,1'-binaphthalene-2,2'-bisdiphenylphosphine (abbreviated as BINAP), 4,5-bisdiphenylphosphino-9,9-dimethylxanthene (abbreviated as Xantphos) or (S)-DTBM-SEGPHOS.

[0007] Specifically, the structural formula of (S)-DTBM-SEGPHOS is

[0008] ,

[0009] The present application can inhibit the generation of side reactions by steric hindrance and improve the selectivity of glycolic aldehyde by selecting a bulky phosphine ligand. The bulky group can protect the rhodium metal center by steric shielding effect, reduce the deactivation caused by metal aggregation or excessive coordination with reactants at high temperature, and limit the coordination configuration of formaldehyde and CO by steric effect, promote the linear insertion of C-C bond to generate glycolic aldehyde, rather than branched insertion to generate formate or condensation byproducts. Moreover, the antioxidant modified phosphine ligand can further enhance the oxidation resistance of the ligand skeleton, reduce the oxidative decomposition of phosphine group (P-C bond) at high temperature, and further improve the thermal stability.

[0010] Optionally, the active metal component accounts for 0.1-5wt% of the total mass of the rhodium catalyst modified by the phosphine ligand. Optionally, the active metal component accounts for 0.1wt%, 0.2wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt% or any value and range therebetween of the total mass of the rhodium catalyst modified by the phosphine ligand.

[0011] Optionally, the preparation method of the antioxidant modified phosphine ligand comprises the following steps:

[0012] S1: Dissolve the phosphine ligand in anhydrous solvent under inert atmosphere, then add n-butyllithium (n-BuLi) to generate a dilithiated intermediate. Optionally, the inert atmosphere can be nitrogen or argon.

[0013] S2: Dissolve pentafluorophenyl bromide (C6F5Br) in anhydrous solvent, then add the dilithiated intermediate solution of step S1 to react, and then extract, reduce pressure and concentrate, and purify to obtain the antioxidant modified phosphine ligand.

[0014] The fluorinated aromatic ring is introduced into the antioxidant modified phosphine ligand, the high bond energy of C-F bond (~485 kJ / mol) can significantly enhance the oxidation resistance of the ligand skeleton, reduce the oxidative decomposition of phosphine group (P-C bond) at high temperature, the hydrophobicity of fluorinated aromatic ring can reduce the attack of water molecules on the rhodium metal center, and the rigid structure of fluorinated aromatic ring can inhibit molecular vibration at high temperature, delay thermal degradation. In addition, in the process of producing glycolic aldehyde by formaldehyde hydroformylation, the strong electron-withdrawing effect of fluorinated aromatic ring can reduce the electron density of rhodium center, weaken the feedback effect of π antibonding orbital of CO, thereby accelerating the CO insertion step and inhibiting excessive hydrogenation, reducing the production of byproducts, and improving the selectivity of glycolic aldehyde.

[0015] Optionally, the molar ratio of the diphosphine ligand, n-butyllithium, and C6F5Br is 1: (2-4): (2-4). Optionally, the molar ratio of the diphosphine ligand, n-butyllithium, and C6F5Br is 1: (2-3): (2-3).

[0016] Optionally, the anhydrous solvent can be anhydrous tetrahydrofuran.

[0017] Optionally, the method for preparing the antioxidant-modified diphosphine ligand further comprises the following steps:

[0018] S01: dissolving the diphosphine ligand, pinacol diboronic acid (B2pin2), and palladium catalyst in a solvent, and reacting at a certain temperature to obtain a monoboronic esterified diphosphine ligand;

[0019] S02: dissolving the monoboronic esterified diphosphine ligand, 4-trifluoromethyl phenylboronic acid (4-CF3-phenylboronic acid), a strong base, and a palladium catalyst in a solvent, and reacting at a certain temperature to obtain a diphosphine ligand-CF3.

[0020] Before introducing the fluorinated aromatic ring, the -CF3 group is introduced on one aromatic ring of the diphosphine ligand through Suzuki coupling, and then the other aromatic ring is subjected to fluorination using a strong nucleophile (n-BuLi), which can ensure the normal progress of the subsequent fluorination reaction. At the same time, the use of 4-(trifluoromethyl) phenylboronic acid to introduce the electron-withdrawing group -CF3 on the diphosphine ligand can reduce the electron density of the Rh metal center, slow down the over-hydrogenation, further slow down the generation of by-products, and improve the selectivity of ethanol aldehyde.

[0021] Optionally, the molar ratio of the diphosphine ligand and pinacol diboronic acid is 1: (1.5-4). Optionally, the molar ratio of the diphosphine ligand and pinacol diboronic acid is 1: (2-3).

[0022] Optionally, the molar ratio of the monoboronic esterified diphosphine ligand, 4-CF3-phenylboronic acid, and a strong base is 1: (1.2-3): (4-6). Optionally, the molar ratio of the monoboronic esterified diphosphine ligand, 4-CF3-phenylboronic acid, and a strong base is 1: (2-3): (4-5).

[0023] Optionally, the palladium catalyst is one or more of palladium acetate, tetrakis(triphenylphosphine)palladium, and dichlorobis(triphenylphosphine)palladium.

[0024] Optionally, the strong base is one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, and cesium carbonate.

[0025] Optionally, in step S01, the certain temperature is 70-120°C. Optionally, in step S01, the certain temperature is 80-110°C.

[0026] Optionally, the certain temperature is 90-120 DEG C in step S02.

[0027] Optionally, the mesoporous material is one or more of MCM-41, SBA-15, SiO2 and CMK-3, and the phosphine ligand modified rhodium catalyst is immobilized on the mesoporous material to improve the cycle stability of the catalyst.

[0028] The second aspect of the application provides a preparation method of the phosphine ligand modified rhodium catalyst, comprising the following steps:

[0029] The rhodium precursor is added into the organic reagent to prepare a rhodium solution with a certain concentration, and then the anti-oxidation modified phosphine ligand is added, and stirring is performed under an inert gas atmosphere, and then centrifugation, washing and drying are sequentially performed to obtain the phosphine ligand modified rhodium catalyst.

[0030] Optionally, the rhodium precursor is one of Rh(acac)(CO)2, RhCl3, HRh(PPh3)2Cl, Rh(PPh3)3Cl and HRh(PPh3)3.

[0031] Optionally, the certain concentration of the rhodium solution is 5-15 mmol / L.

[0032] Optionally, the organic reagent is one of methanol, ethanol, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran and acetylacetone.

[0033] The third aspect of the application provides an application of the phosphine ligand modified rhodium catalyst in a formaldehyde hydroformylation reaction.

[0034] Optionally, in the formaldehyde hydroformylation reaction, the raw material is a mixed gas of formaldehyde, CO and H2, the molar ratio of CO to H2 is 1: (1-4), the reaction temperature is 100-250 DEG C, and the reaction pressure is 5-10 MPa.

[0035] Compared with the prior art, the application at least has one of the following beneficial effects:

[0036] (1) The phosphine ligand modified rhodium catalyst can select a large steric hindrance phosphine ligand to inhibit the generation of side reactions through steric hindrance and improve the selectivity of ethanol aldehyde, and can limit the coordination configuration of formaldehyde and CO through steric effect to promote the linear insertion of C-C bond to generate ethanol aldehyde, and the anti-oxidation modified phosphine ligand can further enhance the oxidation resistance of the ligand skeleton and improve the thermal stability.

[0037] (2) The phosphine ligand after the antioxidation modification treatment introduces fluorinated aromatic ring, which can enhance the oxidation resistance of the ligand skeleton and improve the thermal stability. In addition, in the process of producing ethanol aldehyde by formaldehyde hydroformylation reaction, the strong electron-withdrawing effect of the fluorinated aromatic ring can reduce the electron density of the rhodium center, weaken the feedback effect of the π antibonding orbital of CO, thereby accelerating the CO insertion step and inhibiting excessive hydrogenation, reducing the production of by-products, and improving the selectivity of ethanol aldehyde.

[0038] (3) The -CF3 group is introduced on one aromatic ring of the phosphine ligand through Suzuki coupling before the fluorination reaction, which can reduce the electron density of the Rh metal center, slow down the excessive hydrogenation, further slow down the generation of by-products, and improve the selectivity of ethanol aldehyde. DETAILED DESCRIPTION

[0039] In order to more clearly illustrate the overall concept of the present application, the following will be described in detail in an exemplary manner.

[0040] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, however, the present application can also be implemented in other ways different from those described herein, therefore, the scope of protection of the present application is not limited by the specific embodiments disclosed below.

[0041] Example 1

[0042] In an exemplary embodiment of the present application, the preparation method of the phosphine ligand modified rhodium catalyst comprises the following steps:

[0043] S1: 651 g of BINAP (1 mol) is dissolved in 5 L of anhydrous THF under a nitrogen atmosphere, cooled to -78℃, then 1.96 L of 1.6 M n-BuLi (3.136 mol) is slowly added dropwise, and stirred for 30 min to generate a double-lithiated intermediate.

[0044] S2: 775 g of C6F5Br (3.138 mol) is added dropwise, slowly warmed to room temperature, stirred for 12 h, then 1 L of saturated ammonium chloride is added for quenching reaction, extracted with ethyl acetate, the organic phases are combined, concentrated under reduced pressure, then purified by silica gel column chromatography to obtain BINAP-(C6F5)2. The reaction general formula involved in steps S1 and S2 is as follows:

[0045] BINAP+C6F5Br+n-BuLi→BINAP-(C6F5)2+LiBr+C4H 10

[0046] S3: 2.03 g of RhCl3(0.0097 mol) was dissolved in 970 mL of anhydrous ethanol to prepare a rhodium solution of 10 mmol / L, then 997 g of BINAP-(C6F5)2 was added to the rhodium solution, stirred at room temperature for 6 h under a nitrogen atmosphere, and then reduced by passing H2for 2 h. The double phosphine ligand modified rhodium catalyst was obtained by centrifugation, washing, and drying in sequence. The mass fraction of Rh in the double phosphine ligand modified rhodium catalyst was 0.1 wt%.

[0047] Example 2

[0048] In an exemplary embodiment of the present application, the preparation method of the double phosphine ligand modified rhodium catalyst comprises the following steps:

[0049] S1: 631.3 g of BINAP was dissolved in 5 L of anhydrous THF under a nitrogen atmosphere, cooled to -78°C, and then 1.267 L of 1.6 M n-BuLi (2.028 mol) was slowly added dropwise and stirred for 30 min to form a double lithium intermediate.

[0050] S2: 751.3 g of C6F5Br (3.042 mol) was added dropwise, slowly warmed to room temperature, stirred for 12 h, then 1 L of saturated ammonium chloride was added for quenching, extracted with ethyl acetate, the organic phases were combined, concentrated under reduced pressure, and then purified by silica gel column chromatography to obtain BINAP-(C6F5)3. The reaction general formula involved in steps S1 and S2 is as follows:

[0051] BINAP + C6F5Br + n-BuLi → BINAP-(C6F5)3 + LiBr + C4H 10

[0052] S3: 75.5 g of Rh(acac)(CO)2(0.2915 mol) was dissolved in 19.43 L of anhydrous tetrahydrofuran to prepare a rhodium solution of 15 mmol / L, then 970 g of BINAP-(C6F5)3 was added to the rhodium solution, stirred at room temperature for 8 h under a nitrogen atmosphere, and then centrifuged, washed, and dried in sequence to obtain the double phosphine ligand modified rhodium catalyst. The mass fraction of Rh in the double phosphine ligand modified rhodium catalyst was 3 wt%.

[0053] Example 3

[0054] In an exemplary embodiment of the present application, the preparation method of the double phosphine ligand modified rhodium catalyst comprises the following steps:

[0055] S1: 325.5 g BINAP was dissolved in 3 L of anhydrous tetrahydrofuran under a nitrogen atmosphere, cooled to -78°C, and then 654 mL of 1.6 M n-BuLi (1.046 mol) was slowly added dropwise, and stirred for 30 min to generate a dilithiation intermediate.

[0056] S2: 258.3 g of C6F5Br (1.046 mol) was added dropwise, slowly warmed to room temperature, stirred for 12 h, then 500 ml of saturated ammonium chloride was added for quenching, extracted with ethyl acetate, combined organic phases, concentrated under reduced pressure, and then purified by silica gel column chromatography to obtain BINAP-(C6F5)2. The general reaction formula involved in steps S1 and S2 is as follows:

[0057] BINAP + C6F5Br + n-BuLi → BINAP-(C6F5)2 + LiBr + C4H 10

[0058] S3: 453.3 g of Rh(PPh3)3Cl (0.485 mol) was dissolved in 48.5 L of methanol to prepare a rhodium solution of 10 mmol / L, then 546.7 g of BINAP-(C6F5)2 was added to the rhodium solution, stirred at room temperature under a nitrogen atmosphere for 12 h, and then treated by centrifugation, washing, and vacuum drying in sequence to obtain a phosphine ligand modified rhodium catalyst, and the mass fraction of Rh in the total mass of the phosphine ligand modified rhodium catalyst was 5 wt%.

[0059] Example 4

[0060] In an exemplary embodiment of the present application, the preparation method of the phosphine ligand modified rhodium catalyst comprises the following steps:

[0061] S1: 277.4 g of BIPHEP was dissolved in 3 L of anhydrous tetrahydrofuran under a nitrogen atmosphere, cooled to -78°C, and then 595 mL of 1.6 M n-BuLi (0.952 mol) was slowly added dropwise, and stirred for 30 min to generate a dilithiation intermediate.

[0062] S2: 235.2 g of C6F5Br (0.952 mol) was added dropwise, slowly warmed to room temperature, stirred for 12 h, then 500 ml of saturated ammonium chloride was added for quenching, extracted with ethyl acetate, combined organic phases, concentrated under reduced pressure, and then purified by silica gel column chromatography (petroleum ether / ethyl acetate volume ratio 10:1) to obtain BIPHEP-(C6F5)2. The general reaction formula involved in steps S1 and S2 is as follows:

[0063] BIPHEP + n-BuLi + C6F5Br → BIPHEP-(C6F5)2 + LiBr + C4H 10

[0064] S3: 123.6 g of rhodium dicarbonyl acetylacetone Rh(PPh3)3Cl (0.477 mol) was dissolved in 47.7 L of anhydrous N,N-dimethylformamide to form a 10 mmol / L rhodium solution, then 722.4 g of BIPHEP-(C6F5)2 was added to the rhodium solution, and the mixture was stirred at 50°C for 10 h under a nitrogen atmosphere, and then sequentially subjected to centrifugation, washing, and vacuum drying to obtain 1 kg of phosphine ligand modified rhodium catalyst, and the mass fraction of Rh in the total mass of the phosphine ligand modified rhodium catalyst was 5%.

[0065] Example 5

[0066] In an exemplary embodiment of the present application, the method for preparing the phosphine ligand modified rhodium catalyst comprises the following steps:

[0067] S1: 282.5 g of Xantphos was dissolved in 3 L of anhydrous tetrahydrofuran under a nitrogen atmosphere, and then slowly added with 555 mL of 1.6 M n-BuLi (0.888 mol) dropwise while cooling to -78°C, and the mixture was stirred for 30 min to form a double-lithiated intermediate.

[0068] S2: 219.3 g of C6F5Br (0.888 mol) was added dropwise, and the mixture was slowly warmed to room temperature and stirred for 12 h, then 500 mL of saturated ammonium chloride was added to quench the reaction, and the mixture was extracted with ethyl acetate, and the organic phases were combined and concentrated under reduced pressure, and then purified by silica gel column chromatography (petroleum ether / ethyl acetate volume ratio 10:1) to obtain Xantphos-(C6F5)2. The reaction general formula involved in steps S1 and S2 is as follows:

[0069] Xantphos + n-BuLi + C6F5Br → Xantphos-(C6F5)2 + LiBr + C4H 10

[0070] S3: 123.6 g of rhodium dicarbonyl acetylacetone Rh(PPh3)3Cl (0.477 mol) was dissolved in 47.7 L of anhydrous N,N-dimethylformamide to form a 10 mmol / L rhodium solution, then 722.4 g of BIPHEP-(C6F5)2 was added to the rhodium solution, and the mixture was stirred at 50°C for 10 h under a nitrogen atmosphere, and then sequentially subjected to centrifugation, washing, and vacuum drying to obtain 1 kg of phosphine ligand modified rhodium catalyst, and the mass fraction of Rh in the total mass of the phosphine ligand modified rhodium catalyst was 5%.

[0071] Example 6

[0072] In an exemplary embodiment of the present application, the method for preparing the phosphine ligand modified rhodium catalyst comprises the following steps:

[0073] S01: 138.2 g BINAP (0.22 mol) and 112.9 g pinacolatobisboronic acid (B2pin2) (0.44 mol) were dissolved in 2 L of toluene, 8.05 g of Pd(dppf)Cl2was added, and reflux was carried out at 110°C for 12 hours to obtain a monoboronate-esterified bisphosphine ligand.

[0074] S02: Then 88.8 g of 4-CF3-phenylboronic acid (0.43 mol) and 35.5 g of NaOH (dissolved in 0.5 L of water) were added, and reflux was continued for 24 hours. The liquid was separated, the organic phase was washed with saturated brine, dried, concentrated under reduced pressure, and purified by column chromatography to obtain BINAP-CF3.

[0075] S1: 179.9 g of BINAP-CF3was dissolved in 1.5 L of anhydrous tetrahydrofuran under a nitrogen atmosphere, cooled to -78°C, and then 278 mL of 1.6 M n-BuLi (0.444 mol) was slowly added dropwise. After stirring for 30 min, a dilithiated intermediate was generated.

[0076] S2: 109.6 g of C6F5Br (0.444 mol) was added dropwise, slowly warmed to room temperature, and stirred for 12 h. Then 500 ml of saturated ammonium chloride was added for quenching, extracted with ethyl acetate, the organic phases were combined, concentrated under reduced pressure, and then purified by silica gel column chromatography to obtain BINAP-CF3-(C6F5)2.

[0077] S3: 238.1 g of Rh(PPh3)3Cl (0.255 mol) was dissolved in 25.5 L of anhydrous methanol to prepare a 10 mmol / L rhodium solution. Then 761.9 g of BINAP-CF3-(C6F5)2was added to the rhodium solution, stirred at room temperature under a nitrogen atmosphere for 12 h, and then treated by centrifugation, washing, and vacuum drying in sequence to obtain a bisphosphine ligand-modified rhodium catalyst. Rh accounted for 5 wt% in the total mass of the bisphosphine ligand-modified rhodium catalyst.

[0078] Example 7

[0079] S01: 283.0 g of BIPHEP and 370.3 g of B2pin2were dissolved in 3 L of toluene, 17.8 g of Pd(dppf)Cl2was added, and reflux was carried out at 110°C for 12 hours to obtain a monoboronate-esterified bisphosphine ligand.

[0080] S02: Then 291.6 g of 4-CF3-phenylboronic acid and 633.5 g of cesium carbonate (dissolved in 0.75 L of water) were added, and reflux was continued for 24 hours. The liquid was separated, the organic phase was washed with saturated brine, dried, concentrated under reduced pressure, and purified by column chromatography to obtain BIPHEP-CF3.

[0081] S1: 316 g of BIPHEP-CF3 was dissolved in 2 L of anhydrous tetrahydrofuran under a nitrogen atmosphere, cooled to -78 °C, and then 607.5 mL of 1.6 M n-BuLi (0.972 mol) was slowly added dropwise, and stirred for 30 min to generate a dilithiated intermediate.

[0082] S2: 240 g of C6F5Br (0.972 mol) was added dropwise, slowly warmed to room temperature, stirred for 12 h, then 500 ml of saturated ammonium chloride was added for quenching, extracted with ethyl acetate, the organic phases were combined, concentrated under reduced pressure, and then purified by silica gel column chromatography to obtain BIPHEP-CF3-(C6F5)2.

[0083] S3: 454 g of Rh(PPh3)3Cl (0.486 mol) was dissolved in 48.6 L of anhydrous methanol to prepare a 10 mmol / L rhodium solution, then 546 g of BIPHEP-CF3-(C6F5)2 was added to the rhodium solution, stirred at room temperature under a nitrogen atmosphere for 20 h, then treated by centrifugation, washing, and vacuum drying in sequence to obtain a diphosphine ligand modified rhodium catalyst, and the Rh accounted for 5 wt% in the total mass of the diphosphine ligand modified rhodium catalyst.

[0084] Example 8

[0085] Based on Example 7, the main difference is that the diphosphine ligand BIPHEP is replaced by Xantphos, and the other steps are similar to Example 7.

[0086] Example 9

[0087] Based on Example 1, the main difference is that the active metal component accounts for 0.05 wt% in the total mass of the diphosphine ligand modified rhodium catalyst.

[0088] Comparative Example 1

[0089] Based on Example 1, the main difference is that the diphosphine ligand is not subjected to antioxidant modification treatment.

[0090] Comparative Example 2

[0091] Based on Example 1, the main difference is that the diphosphine ligand is bis(diphenylphosphino)methane.

[0092] Test Example:

[0093] The catalyst prepared in the above examples and comparative examples was applied to the formaldehyde hydroformylation reaction: the catalyst prepared in the examples and comparative examples was added into a reaction kettle, DMF was added as solvent, then formaldehyde aqueous solution (concentration 40%) was pumped in, CO and H2 mixed gas was introduced, the molar ratio of CO and H2 was 1:2, the reaction temperature was 240℃, the reaction pressure was 5 MPa, and the stirring speed was 800 rpm. The product was analyzed by gas chromatography after cooling, and the results are shown in Table 1.

[0094] Table 1

[0095]

[0096] Referring to Table 1, the biphosphine ligand modified rhodium catalyst prepared in the application was applied to the production of ethanol aldehyde by formaldehyde hydroformylation. At high temperature (more than 200℃), the formaldehyde conversion rate was not less than 40%, and the ethanol aldehyde selectivity was not less than 35%. It is proved that the biphosphine ligand modified rhodium catalyst has good high-temperature stability and high selectivity.

[0097] Comparative Example 1 and Example 1 are mainly different in that the biphosphine ligand is not subjected to antioxidant modification treatment. At high temperature, the biphosphine ligand is oxidized and decomposed, resulting in the agglomeration and deactivation of rhodium metal.

[0098] The above only describes the embodiments of the application and is not intended to limit the application. The application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the application shall be included in the scope of the claims of the application.

Claims

1. A rhodium catalyst modified with a diphosphine ligand, characterized in that, The phosphine ligand modified rhodium catalyst comprises an active metal component and an antioxidant modified phosphine ligand, the active metal component is Rh, and the antioxidant modified phosphine ligand is one or more of 2,2'-bis(diphenylphosphino) biphenyl, 1,1'-binaphthalene-2,2'-bisdiphenylphosphine, 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene or (S)-DTBM-SEGPHOS; The method for preparing the antioxidant modified phosphine ligand comprises the following steps: S1: dissolving the phosphine ligand in anhydrous solvent under an inert atmosphere, and then adding n-butyllithium to generate a dilithiated intermediate; S2: dissolving pentafluorophenyl bromide in anhydrous solvent, and then adding the dilithiated intermediate solution obtained in step S1 to react, and then sequentially performing extraction, vacuum concentration and purification to obtain the antioxidant modified phosphine ligand; The molar ratio of the phosphine ligand, n-butyllithium and pentafluorophenyl bromide is 1: (2-4): (2-4).

2. The diphosphine ligand-modified rhodium catalyst according to claim 1, wherein, The active metal component accounts for 0.1-5 wt% of the total mass of the phosphine ligand modified rhodium catalyst.

3. The diphosphine ligand-modified rhodium catalyst according to claim 1, wherein The method for preparing the antioxidant modified phosphine ligand further comprises the following steps: S01: dissolving the phosphine ligand, pinacol diboronic acid and a palladium catalyst in a solvent, and then reacting at a certain temperature to obtain a monoboronic esterified phosphine ligand; S02: dissolving the monoboronic esterified phosphine ligand, 4-CF3-phenylboronic acid, a strong base and a palladium catalyst in a solvent, and then reacting at a certain temperature to obtain a phosphine ligand-CF3.

4. The diphosphine ligand-modified rhodium catalyst according to claim 3, wherein The molar ratio of the phosphine ligand and pinacol diboronic acid is 1: (1.5-4); The molar ratio of the monoboronic esterified phosphine ligand, 4-CF3-phenylboronic acid and the strong base is 1: (1.2-3): (4-6).

5. The diphosphine ligand-modified rhodium catalyst according to claim 3, wherein The palladium catalyst is one or more of palladium acetate, tetrakis(triphenylphosphine)palladium and dichlorobis(triphenylphosphine)palladium; The strong base is one or more of sodium hydroxide, potassium hydroxide, potassium carbonate and cesium carbonate.

6. A process for the preparation of a rhodium catalyst modified with a diphosphine ligand according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: adding a rhodium precursor into an organic reagent to prepare a rhodium solution with a certain concentration, then adding the antioxidant modified phosphine ligand, stirring under an inert gas atmosphere, and then sequentially performing centrifugation, washing and drying treatment to obtain the phosphine ligand modified rhodium catalyst.

7. The production method according to claim 6, wherein The rhodium precursor is one of Rh(acac)(CO)2, RhCl3, HRh(PPh3)2Cl, Rh(PPh3)3Cl and HRh(PPh3)3.

8. The phosphine ligand modified rhodium catalyst according to any one of claims 1-5 is applied in a formaldehyde hydroformylation reaction.

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