Catalyst for adjusting normal / isomeric ratio of butyraldehyde product and adjusting method thereof

Abstract

The invention provides a catalyst for adjusting the normal / isomeric ratio of a butyraldehyde product and an adjusting method of the catalyst. The catalyst comprises a ligand A, a ligand B and a rhodium substrate, wherein the ligand A is one or more of # imgabs 0 #, # imgabs 1 #, # imgabs 2 # or # imgabs 3 #; and the ligand B is # imgabs4 #. The invention provides a catalyst for adjusting the normal / isomer ratio of a formaldehyde product in the process of preparing butyraldehyde through a propylene hydroformylation reaction, and the catalyst has propylene hydroformylation catalytic activity after complexing a ligand A, a ligand B and a rhodium substrate based on an accurately designed ligand combination. A mixed ligand composed of a ligand A and a ligand B according to a certain proportion is added in a propylene hydroformylation reaction to be complexed with rhodium, so that the n-iso-ratio of butyraldehyde can be flexibly adjusted in a range of 1-17.3.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a catalyst for adjusting the normal-to-isobutyraldehyde ratio of a butyraldehyde product and a method for adjusting the same. Background Art

[0002] The products produced by the carbonylation of propylene and CO to butyraldehyde include n-butyraldehyde and isobutyraldehyde. n-Butyraldehyde undergoes condensation and dehydration under the catalytic action of sodium hydroxide to produce octenal. Octenal is then hydrogenated to produce crude octanol, which is then distilled to obtain the final octanol. Therefore, plants aiming to produce butyraldehyde and octanol often desire a high n-to-isobutyraldehyde ratio during the propylene carbonylation process to yield more n-butyraldehyde.

[0003] It's worth noting that the addition reaction of isobutyraldehyde with formaldehyde produces hydroxytrimethylacetaldehyde, which can then be hydrogenated to produce neopentyl glycol. Neopentyl glycol is being adopted in a growing number of applications, such as as a plasticizer in the production of unsaturated resins, oil-free alkyd resins, polyurethane foams and elastomers, a surfactant, insulation materials, printing inks, a polymerization inhibitor, and an additive for synthetic aviation lubricants. Driven by this, market demand for isobutyraldehyde is gradually expanding.

[0004] As demand for isobutyraldehyde increases, the carbonylation of propylene with carbon monoxide to produce butyraldehyde will no longer simply pursue a high normal-to-isobutyraldehyde ratio. Effectively adjusting the ratio of normal-to-isobutyraldehyde by adjusting the catalyst in response to market fluctuations would be more in line with market conditions.

[0005] Currently, a consensus has emerged regarding the reaction mechanism of the carbonylation of propylene and carbon monoxide to butyraldehyde: the primary reason for the different product distributions of n-butyraldehyde and iso-butyraldehyde is the unique electronic structure differences within the catalyst's active center and the steric hindrance surrounding the active center, which are primarily governed by the reaction kinetics. Rhodium exhibits excellent catalytic activity in the carbonylation of propylene due to its ability to simultaneously activate the C=C double bond, carbon monoxide, and hydrogen, enabling the overall reaction to proceed under relatively mild conditions. Organic ligands coordinated with noble metals form a unique spatial structure, resulting in varying degrees of ease of binding between the different carbon atoms in the propylene C=C double bond and the noble metal at the active center, leading to differences in the activation energy barrier for the formation of n-butyraldehyde and iso-butyraldehyde. However, currently reported methods utilize ligands with a single function during the reaction, resulting in a single catalyst performance and limited flexibility in adjusting the n-butyraldehyde to iso-butyraldehyde ratio.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The first object of the present invention is to provide a catalyst for adjusting the normal-to-isobutyraldehyde ratio of a butyraldehyde product during the preparation of butyraldehyde by propylene hydroformylation. The catalyst is based on a precisely designed ligand combination, thereby achieving effective regulation of the normal-to-isobutyraldehyde ratio of the butyraldehyde product, thereby significantly improving the responsiveness of butyraldehyde production to the market. The present invention mainly catalyzes propylene hydroformylation by complexing ligands A and B with a rhodium substrate, and then flexibly adjusts the butyraldehyde normal-to-isobutyraldehyde ratio within the range of 1-17.3 by adjusting the molar ratio between ligand A and ligand B.

[0008] The second object of the present invention is to provide a method for adjusting the above-mentioned catalyst, which can achieve effective regulation of the normal-to-isobutyraldehyde ratio of the butyraldehyde product without changing the reaction equipment and reaction conditions, thereby significantly improving the flexible response of production to the market.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted: A catalyst for adjusting the normal-to-isobutyraldehyde ratio of a butyraldehyde product, comprising a ligand A, a ligand B, and a rhodium substrate; Wherein the ligand A is 、 、 or One or more of; The ligand B is .

[0010] Preferably, as a further specific embodiment, the ligand A is , the ligand B is .

[0011] Preferably, as a further specific embodiment, the ligand A is , the ligand B is .

[0012] Preferably, as a further specific embodiment, the ligand A is , the ligand B is .

[0013] Preferably, as a further specific embodiment, the ligand A is , the ligand B is .

[0014] In the present invention, a catalyst is prepared by complexing ligand A, ligand B and a rhodium substrate. The catalyst can adjust the normal-to-iso ratio of the butyraldehyde product during the preparation of butyraldehyde by propylene hydroformylation reaction, thereby achieving flexible adjustment of the normal-to-iso ratio of the butyraldehyde within the range of 1-17.3. The ligand A selected in the present invention is 1,1-binaphthyl-2,2-bisdiphenylphosphine, triphenyl phosphite, triphenylphosphine and tri(o-methylphenyl)phosphine. After a series of creative work, the inventors found that only by using 1,1-binaphthyl-2,2-bisdiphenylphosphine, the catalyst can adjust the normal-to-iso ratio of the butyraldehyde product during the preparation of butyraldehyde by propylene hydroformylation reaction, thereby achieving flexible adjustment of the normal-to-iso ratio of the butyraldehyde within the range of 1-17.3. The catalyst, which is formed by combining any one of 2-bis(diphenylphosphine), triphenyl phosphite, triphenylphosphine, and tri(o-methylphenyl)phosphine with ligand B (4,5-bis(diphenylphosphine-9,9-dimethylxanthene), and then complexing with a rhodium substrate, has the ability to adjust the normal-to-iso ratio of the butyraldehyde product. This is because the steric hindrance of the ligand determines the insertion mode of propylene during the propylene hydroformylation reaction. Therefore, the present invention fixes the ligand configuration of Rh, thereby inhibiting the formation of branched transition states and improving the normal-to-iso ratio. The catalyst obtained by simply adjusting the molar ratio between ligand A and ligand B can achieve flexible adjustment of the normal-to-iso ratio of the butyraldehyde product. Therefore, the present invention uses four ligands A, ligand B and a rhodium substrate for complexation, and by adjusting the molar ratio between ligand A and ligand B, the normal-to-iso ratio of the butyraldehyde product can be flexibly adjusted within the range of 1-17.3. Compared with the method of using a large number of different ligands to achieve different butyraldehyde normal-to-iso ratios in traditional technologies, the catalyst provided by the present invention only requires the simple mixing and use of two fixed ligands to achieve flexible adjustment of the butyraldehyde normal-to-iso ratio. The adjustment method is simple, easy to adjust, and the reaction rate is faster.

[0015] Preferably, as a further specific embodiment, the molar ratio of ligand A to ligand B is 1:100-100:1; Preferably, the mass ratio of the ligand A to the ligand B is 1:10-10:1.

[0016] When the present invention uses a catalyst formed by the complexation of ligand A, ligand B and rhodium substrate to catalyze the n-butyraldehyde product, since BINAP, triphenyl phosphite, PPh3 and P(o-Tol)3 in ligand A all have large steric hindrance, the rigid binaphthyl skeleton of BINAP makes it have strong steric hindrance, thereby hindering the ligand of linear propylene, and thus promoting the formation of branched paths, when the molar ratio of BINAP is greater than that of ligand B, the wide bite angle advantage of ligand B can be suppressed, further reducing the selectivity of n-butyraldehyde, while triphenyl phosphite, PPh3 and Although P(o-Tol)3 and the other two are monophosphine ligands with less steric hindrance than BINAP, they will still occupy the coordination site of Rh when their molar ratio is too high, thereby weakening the linear regulation effect of Xantphos. Moreover, the steric hindrance of P(o-Tol)3 is greater among the three, which is more likely to lead to an increase in branched products. At the same time, since some of the ligands in ligand A are electron-rich ligands (such as PPh3 and P(o-Tol)3), the electron-rich ligands will increase the electron density of Rh, thereby stabilizing the branched transition state (isobutyraldehyde path), while electron-deficient ligands (such as triphenyl phosphite) should theoretically promote the formation of linear products. However, since its steric hindrance may still dominate, it will still lead to a decrease in the normal-iso ratio; in addition, ligand B has a wide bite angle, which enables it to form a stable chelate structure with the rhodium substrate, which is conducive to promoting the end-coordination of linear propylene and inhibiting the asymmetric coordination of the Rh center, thereby reducing the branched path, thereby further improving the selectivity of n-butyraldehyde. Therefore, the present invention adopts ligand A and ligand B as mixed ligands and adjusts the molar ratio between the two to achieve flexible adjustment of the normal-iso ratio of the butyraldehyde product. This is because when the molar ratio of ligand A is lower than that of ligand B, the mixed ligand A and ligand B are In the obtained mixed ligand, ligand B is dominant, and Rh mainly forms a stable chelate structure with Xantphos, thereby providing a wide coordination space, thereby promoting linear insertion, and thus achieving a higher positive-isomer ratio; when the molar ratio of ligand A is higher than that of ligand B, ligand A is dominant in the mixed ligand obtained by mixing ligand A and ligand B. Rh is more likely to combine with the monodentate ligand in ligand A to form a monophosphine ligand environment with less spatial constraint, thereby better allowing branched olefin insertion; and if ligand A is BINAP, its rigid structure will force Rh to enter the branched-selective configuration, thereby reducing the positive-isomer ratio.

[0017] Therefore, it can be seen from the above that the molar ratio between ligand A and ligand B will significantly affect the normal-to-isobutyraldehyde ratio. This is because the present invention mainly adjusts the molar ratio between ligand A and ligand B to achieve flexible adjustment of the normal-to-isobutyraldehyde ratio within the range of 1-17.3.

[0018] Preferably, as a further specific embodiment, the rhodium substrate is rhodium (1,5-cyclooctadiene) chloride dimer or rhodium dicarbonyl acetylacetonate.

[0019] In the propylene hydroformylation reaction, the choice of rhodium substrate has an important influence on the catalyst activity and selectivity. When the rhodium substrate is selected as chlorinated (1,5-cyclooctadiene) rhodium dimer, it has high ligand flexibility. The COD contained in it is a weak coordination ligand and is easy to dissociate under the reaction conditions, thereby quickly releasing coordination vacancies, which is convenient for introducing the target ligand. At the same time, its Cl - The weak coordination ability of rhodium can adjust the electron density of the rhodium center, thereby slightly increasing the positive-isomer ratio. Therefore, when the rhodium substrate is rhodium (1,5-cyclooctadiene) chloride dimer, it is more stably bound to ligand B because its rapidly dissociated COD and chloride ions can more efficiently form a chelate structure, resulting in a higher positive-isomer ratio. If dicarbonyl acetylacetonate rhodium is selected, due to the two CO ligands it contains, it can directly participate in the catalytic cycle in the hydroformylation reaction without the need for additional introduction of CO for activation. Moreover, when it is combined with a rigid bidentate ligand, due to the presence of the initial CO ligand, it is easier to form a highly selective planar tetragonal configuration, further improving the positive-isomer ratio.

[0020] The present invention also provides a method for adjusting the normal-to-isobutyraldehyde ratio of a butyraldehyde product using the above-mentioned catalyst for adjusting the normal-to-isobutyraldehyde ratio of the butyraldehyde product, comprising the following steps: preparing a catalyst, and then adding the catalyst into a solvent and stirring to dissolve it to obtain a mixed solution; The temperature and pressure are set, and then propylene, nitric oxide and hydrogen are introduced into the mixed liquid in sequence.

[0021] Preferably, as a further specific embodiment, the amount of the catalyst used is 0.005%-2% of the total mass of the solvent.

[0022] In the invention, the amount of catalyst and solvent used is also subject to certain restrictions. When the amount of catalyst used is 0.005%-2% of the total mass of the solvent, the effect that can be achieved is excellent; if the amount of solvent used is too small and the catalyst concentration is high, it may cause ligand aggregation or precipitation, resulting in uneven catalytic activity; and if the solvent is excessive, it will accelerate the decomposition or loss of the catalyst, thereby leading to an increase in by-products, and indirectly affecting the catalyst's effect on regulating the positive-isomer ratio.

[0023] Preferably, as a further specific embodiment, the solvent is toluene, the temperature is 60-120° C., and the pressure is 0.5-3.0 MPa; Preferably, the pressure is 1.5-3.0 MPa.

[0024] In the present invention, when the normal-to-isobutyraldehyde ratio is adjusted by using a catalyst, temperature and pressure are very important to the present invention. When the temperature is 60-120°C and the pressure is 0.5-3.0 MPa; preferably, when the pressure is 1.5-3.0 MPa, the effect that can be achieved is excellent. If the temperature is too high, the rhodium substrate may decompose or the ligand may be oxidized, thereby reducing the catalytic efficiency and affecting the adjustment of the normal-to-isobutyraldehyde ratio; if the temperature is too low, the reaction rate may be too low.

[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a catalyst for adjusting the normal-to-isobutyraldehyde ratio of formaldehyde products during the preparation of butyraldehyde by propylene hydroformylation reaction. The catalyst is based on a precisely designed ligand combination. After ligand A and ligand B are complexed with a rhodium substrate, the catalyst has catalytic activity for propylene hydroformylation. By adding a mixed ligand composed of ligand A and ligand B in a certain ratio into the propylene hydroformylation reaction and complexing with rhodium, the normal-to-isobutyraldehyde ratio can be flexibly adjusted within the range of 1-17.3.

[0026] (2) The present invention provides a method for regulating the above-mentioned catalyst, which can achieve effective regulation of the normal-to-isobutyraldehyde ratio of the butyraldehyde product without changing the reaction equipment and reaction conditions, thereby significantly improving the flexible response of production to the market. DETAILED DESCRIPTION

[0027] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. However, those skilled in the art will understand that the embodiments described below are part of the embodiments of the present invention, not all of them, and are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] In order to more clearly illustrate the technical solutions of the present invention, specific embodiments are provided below for illustration.

[0029] Example 1 The specific steps of the regulation method of the present invention are: In a 50 ml autoclave, 5 mg (0.01 mmol) of (1,5-cyclooctadiene) rhodium chloride dimer, 12.6 mg (0.02 mmol) of ligand A, wherein ligand A is 1,1-binaphthyl-2,2-bisdiphenylphosphine, 11.8 mg (0.02 mmol) of ligand B, and 4.0 ml of toluene were added; Then, 2.5 bar of propylene, 8.7 bar of carbon monoxide, and 8.7 bar of hydrogen were introduced in sequence, and the temperature was raised to 80°C while stirring. The reaction was then stirred at this temperature for 4 hours, and the reaction solution was cooled to 0°C; After slowly releasing the pressure, samples were taken for gas chromatography analysis. According to the gas chromatography results, the propylene conversion rate was >99%, and the ratio of n-butyraldehyde to isobutyraldehyde in the product was 5.2.

[0030] Example 2 In a 50 ml autoclave, 5 mg (0.019 mmol) of dicarbonyl acetylacetonate rhodium, 7.2 mg (0.012 mmol) of ligand A, wherein ligand A is 1,1-binaphthyl-2,2-bisdiphenylphosphine, 15.7 mg (0.027 mmol) of ligand B, and 4.0 ml of toluene were added; Then, 2.5 bar of propylene, 8.7 bar of carbon monoxide, and 8.7 bar of hydrogen were introduced in sequence, and the temperature was raised to 120°C while stirring; The reaction was stirred at this temperature for 4 hours, and the reaction solution was cooled to 0°C and then slowly depressurized. Samples were taken for gas chromatography analysis. According to the gas phase results, the propylene conversion rate was >99%, and the ratio of n-butyraldehyde to isobutyraldehyde in the product was 8.8.

[0031] Example 3 In a 50 ml autoclave, 5 mg (0.01 mmol) of (1,5-cyclooctadiene) rhodium chloride dimer, 6.3 mg (0.02 mmol) of ligand A, 11.8 mg (0.02 mmol) of ligand B, and 4.0 ml of toluene were added, wherein ligand A was triphenyl phosphite; Then, 2.5 bar of propylene, 8.7 bar of carbon monoxide, and 8.7 bar of hydrogen were introduced in sequence, and the temperature was raised to 80°C while stirring; The reaction was stirred at this temperature for 4 hours, and the reaction solution was cooled to 0°C. After slowly releasing the pressure, a sample was taken for gas chromatography analysis. According to the gas phase results, the propylene conversion rate was >99%, and the ratio of n-butyraldehyde to isobutyraldehyde in the product was 6.7.

[0032] Example 4 In a 50 ml autoclave, 5 mg (0.01 mmol) of (1,5-cyclooctadiene) rhodium chloride dimer, 5.3 mg (0.02 mmol) of ligand A, 11.8 mg (0.02 mmol) of ligand B and 4.0 ml of toluene were added, wherein ligand A was triphenylphosphine; Then, 2.5 bar of propylene, 8.7 bar of carbon monoxide, and 8.7 bar of hydrogen were introduced in sequence, and the temperature was raised to 120°C while stirring; The reaction was stirred at this temperature for 4 hours, and the reaction solution was cooled to 0° C. After slowly releasing the pressure, a sample was taken for gas chromatography analysis. The gas phase results showed that the propylene conversion rate was >99%, and the ratio of n-butyraldehyde to isobutyraldehyde in the product was 4.9.

[0033] Example 5 In a 50 ml autoclave, 10 mg (0.02 mmol) of (1,5-cyclooctadiene) rhodium chloride dimer, 12.3 mg (0.04 mmol) of ligand A, 23.5 mg (0.04 mmol) of ligand B and 4.0 ml of toluene were added, wherein ligand A was tri(o-methylphenyl)phosphine; 2.5 bar of propylene, 8.7 bar of carbon monoxide, and 8.7 bar of hydrogen were introduced in sequence, and the temperature was raised to 60°C while stirring.

[0034] The reaction was stirred at this temperature for 4 hours, and the reaction solution was cooled to 0° C. After slowly releasing the pressure, a sample was taken for gas chromatography analysis. The gas phase results showed that the propylene conversion rate was >99%, and the ratio of n-butyraldehyde to isobutyraldehyde in the product was 6.7.

[0035] Comparative Example 1 The specific implementation is consistent with Example 1, except that the ligand C with the following structure is used to replace the ligand B and the molar ratio between the ligand B and the ligand C is adjusted to obtain comparative examples 1-5, wherein the specific results are shown in Table 1 below;

[0036] Table 1 Regulation of n-isobutyraldehyde ratio by ligand A-1 and ligand C

[0037] Experimental Example 1 The specific implementation is consistent with Example 1, except that the molar ratio between ligand A and ligand B is adjusted to set Experimental Examples 1-5, and then the normal-isobutyraldehyde ratio of the butyraldehyde products of Experimental Examples 1-5 is measured. The final results are shown in Table 2 below. Table 2 Regulation of n-isobutyraldehyde ratio by ligand A and ligand B

[0038] Experimental Example 2 The specific implementation is consistent with Example 2, except that the molar ratio between ligand A and ligand B is adjusted to set Experimental Examples 6-11, and then the normal-isobutyraldehyde ratio of the butyraldehyde product of Experimental Examples 6-11 is measured. The final results are shown in Table 3 below; Table 3 Regulation of n-isobutyraldehyde ratio by ligand A and ligand B

[0039] Experimental Example 3 The specific implementation method is consistent with Example 3, except that the molar ratio between ligand A and ligand B is adjusted to set Experimental Examples 12-16, and then the normal-isobutyraldehyde ratio of the butyraldehyde products of Experimental Examples 12-16 is measured. The final results are shown in Table 4 below; Table 4 Regulation of n-isobutyraldehyde ratio by ligand A and ligand B

[0040] Experimental Example 4 The specific implementation method is consistent with Example 4, except that the molar ratio between ligand A and ligand B is adjusted to set Experimental Examples 17-21, and then the normal-isobutyraldehyde ratio of the butyraldehyde products of Experimental Examples 17-21 is measured. The final results are shown in Table 5 below; Table 5 Regulation of n-isobutyraldehyde ratio by ligand A and ligand B

[0041] Experimental Example 5 The specific implementation method is consistent with Example 5, except that the molar ratio between ligand A and ligand B is adjusted to set Experimental Examples 22-26, and then the normal-isobutyraldehyde ratio of the butyraldehyde products of Experimental Examples 22-26 is measured. The final results are shown in Table 6 below; Table 6 Regulation of n-isobutyraldehyde ratio by ligand A and ligand B

[0042] Therefore, it can be seen from the above Examples 1-5, Comparative Examples and Experimental Examples 1-5 that in the present invention, a catalyst is prepared by complexing ligand A, ligand B and a rhodium substrate, and the catalyst can adjust the normal-iso ratio of the butyraldehyde product during the preparation of butyraldehyde by propylene hydroformylation reaction, thereby achieving flexible adjustment of the normal-iso ratio of butyraldehyde within the range of 1-17.3, wherein the ligand A selected in the present invention are 1,1-binaphthyl-2,2-bisdiphenylphosphine, triphenyl phosphite, triphenylphosphine and tri(o-methylphenyl)phosphine. After a series of creative work, the inventors found that only by adopting The catalyst produced by combining any one of 1,1-binaphthyl-2,2-bisdiphenylphosphine, triphenyl phosphite, triphenylphosphine, and tri(o-methylphenyl)phosphine with ligand B (4,5-bisdiphenylphosphine-9,9-dimethylxanthene) to form a mixed ligand and then complexing it with a rhodium substrate has the ability to adjust the normal-to-isomer ratio of the butyraldehyde product. This is because during the propylene hydroformylation reaction, the steric hindrance of the ligand determines the insertion mode of propylene. Therefore, the present invention uses a rigid bidentate ligand to fix the ligand configuration of Rh, thereby inhibiting the formation of branched transition states and thus improving the normal-to-isomer ratio. When a chiral or rigid bidentate phosphine ligand is complexed with metallic rhodium (Rh), the catalyst obtained by simply adjusting the molar ratio between ligand A and ligand B can achieve flexible adjustment of the normal-to-isomer ratio of the butyraldehyde product. Therefore, the present invention uses four ligands A, ligand B and a rhodium substrate for complexation, and by adjusting the molar ratio between ligand A and ligand B, the normal-to-iso ratio of the butyraldehyde product can be flexibly adjusted within the range of 1-17.3. Compared with the method of using a large number of different ligands to achieve different butyraldehyde normal-to-iso ratios in traditional technologies, the catalyst provided by the present invention only requires the simple mixing and use of two fixed ligands to achieve flexible adjustment of the butyraldehyde normal-to-iso ratio. The adjustment method is simple, easy to adjust, and the reaction rate is faster.

[0043] It can be seen from the comparative example that when a ligand other than ligand A is selected and mixed with ligand B, it does not have the ability to adjust the normal-to-isobutyraldehyde ratio of the butyraldehyde product. Therefore, for the present invention, only by selecting ligand A and ligand B as mixed ligands can the catalyst prepared therefrom achieve flexible adjustment of the normal-to-isobutyraldehyde ratio of the butyraldehyde product.

[0044] As can be seen from the embodiments and experimental examples, the molar ratio between ligand A and ligand B significantly affects the normal-to-iso ratio of butyraldehyde. This is because the present invention mainly adjusts the molar ratio between ligand A and ligand B to achieve flexible regulation of the normal-to-iso ratio of butyraldehyde in the range of 1-17.3. When the catalyst formed by the complexation of ligand A, ligand B and rhodium substrate is used to catalyze the normal-to-iso ratio of butyraldehyde product, BINAP, triphenyl phosphite, PPh3 and P(o-Tol)3 in ligand A all have large steric hindrance, and the rigid binaphthyl skeleton of BINAP makes it have strong steric hindrance, thereby hindering the ligand of linear propylene, thereby promoting the formation of branched propylene. Therefore, when the molar ratio of BINAP is greater than that of ligand B, the wide bite angle advantage of ligand B can be suppressed, further reducing the selectivity of n-butyraldehyde. Although triphenyl phosphite, PPh3 and P(o-Tol)3 are monophosphine ligands with smaller steric hindrance than BINAP, when their molar ratio is too high, they will still occupy the coordination site of Rh, thereby weakening the linear regulation effect of Xantphos. Among the three, P(o-Tol)3 has greater steric hindrance, which is more likely to lead to an increase in branched products. At the same time, since some of the ligands in ligand A are electron-rich ligands (such as PPh3 and P(o-Tol)3), the electron-rich ligands will increase the electron density of Rh, thereby stabilizing The branched transition state (isobutyraldehyde path) is determined, and although the electron-deficient ligand (such as triphenyl phosphite) should theoretically promote the formation of linear products, its steric hindrance may still dominate, thus still leading to a decrease in the normal-isobutyraldehyde ratio; in addition, ligand B has a wide bite angle, so that it can form a stable chelate structure with the rhodium substrate, which is conducive to promoting the end-position coordination of linear propylene and inhibiting the asymmetric coordination of the Rh center, thereby reducing the branched path, thereby further improving the selectivity of n-butyraldehyde. Therefore, the present invention adopts ligand A and ligand B as mixed ligands and adjusts the molar ratio between the two to achieve flexible adjustment of the normal-isobutyraldehyde ratio. This is because when the ligand When the molar ratio of A is lower than that of ligand B, ligand B is dominant in the mixed ligand obtained by mixing ligand A and ligand B, and Rh mainly forms a stable chelate structure with Xantphos, thereby providing a wide coordination space, thereby promoting linear insertion, and thus achieving a higher positive-isomer ratio; when the molar ratio of ligand A is higher than that of ligand B, ligand A is dominant in the mixed ligand obtained by mixing ligand A and ligand B, and Rh is more likely to combine with the monodentate ligand in ligand A to form a monophosphine ligand environment with less spatial constraint, thereby better allowing the insertion of branched olefins; and if ligand A is BINAP, its rigid structure will force Rh to enter the branched-selective configuration, thereby reducing the positive-isomer ratio.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A catalyst for adjusting the normal-to-isobutyraldehyde ratio of a butyraldehyde product, characterized in that: The catalyst comprises ligand A, ligand B and rhodium substrate; Wherein the ligand A is 、 、 or Any of; The ligand B is .

2. The catalyst according to claim 1, characterized in that The ligand A is , the ligand B is .

3. The catalyst according to claim 1, characterized in that The ligand A is , the ligand B is .

4. The catalyst according to claim 1, characterized in that The ligand A is , the ligand B is .

5. The catalyst according to claim 1, characterized in that The ligand A is , the ligand B is .

6. The catalyst according to claim 1, characterized in that The molar ratio of ligand A to ligand B is (1:100)-(100:1); Preferably, the mass ratio of the ligand A to the ligand B is (1:10)-(10:1).

7. The catalyst according to claim 1, characterized in that The rhodium substrate is rhodium (1,5-cyclooctadiene) chloride dimer or rhodium dicarbonyl acetylacetonate.

8. A method for adjusting the normal-to-isobutyraldehyde ratio of a butyraldehyde product using the catalyst for adjusting the normal-to-isobutyraldehyde ratio of a butyraldehyde product according to any one of claims 1 to 7, characterized in that: The following steps are involved: preparing a catalyst, and then adding the catalyst into a solvent and stirring to dissolve it to obtain a mixed solution; The temperature and pressure are set, and then propylene, nitric oxide and hydrogen are introduced into the mixed liquid in sequence.

9. The method for adjusting the normal isotropic ratio of butyraldehyde product by using the catalyst for adjusting the normal isotropic ratio of butyraldehyde product according to claim 8, characterized in that: The amount of the catalyst used is 0.005%-2% of the total mass of the solvent.

10. The method for adjusting the normal-to-isobutyraldehyde ratio of a butyraldehyde product using the catalyst for adjusting the normal-to-isobutyraldehyde ratio of a butyraldehyde product according to claim 8, characterized in that: The solvent is toluene, the temperature is 60-120° C., and the pressure is 0.5-3.0 MPa; Preferably, the pressure is 1.5-3.0 MPa.

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