A hydrolysis-resistant catalyst for increasing the production of isobutyraldehyde through propylene hydroformylation and its application.

Abstract

This invention provides a hydrolysis-resistant catalyst for increasing the production of isobutyraldehyde through propylene hydroformylation and its application. The catalyst comprises a ligand and a metal center compound. The ligand has the structure shown in Formula I. The catalyst system of this invention is characterized by hydrolysis resistance and high stability. It is used to catalyze the reaction of propylene with syngas, exhibiting high reactivity, good selectivity, low metal catalyst dosage, and high propylene conversion rate. The positive-to-isobutyraldehyde ratio can reach 1.0 to 1.1:1, thereby achieving the goal of increasing isobutyraldehyde production.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical synthesis and relates to a hydrolysis-resistant catalyst for increasing the production of isobutyraldehyde through propylene hydroformylation and its application. Background Technology

[0002] Hydroformation, also known as the OXO reaction, refers to the reaction of olefins with syngas (H2 and CO) under transition metal catalysis to produce aldehydes or alcohols. First discovered by O. Roelen in 1938 at Ruhr Chemical Company in Germany during Fischer-Tropsch synthesis, it was quickly applied to the hydroformylation of propylene to butyraldehyde and has now become one of the most important homogeneous catalytic reactions in petrochemicals. Aldehydes can be further converted into alcohols, acids, esters, aldol condensation products, and acetals, which are widely used in pharmaceuticals, pesticides, fragrances, detergents, plasticizers, surfactants, and other applications.

[0003] Isobutyraldehyde is an important organic chemical raw material, widely used as a solvent or plasticizer. Many fine chemical products can be derived from isobutyraldehyde, such as isobutanol, neopentyl glycol, methacrylic acid (MAA), methyl methacrylate (MMA), 2,2,4-trimethyl-1,3-pentanediol (TMPD), methyl ethyl ketone, calcium pantothenate, isobutyrate, and isobutyronitrile. Furthermore, these products can be used as raw materials to synthesize even more chemical products, all of which have wide applications. With the development of the petrochemical industry, the demand for isobutyraldehyde is increasing.

[0004] Industrially, isobutyraldehyde is mainly derived from the byproduct of the carbonylation synthesis of butanol and octanol. In recent years, butanol and octanol production units have strived to increase the production of n-butyraldehyde by optimizing or adjusting the n-isorhodium ratio. For example, the currently popular "low-pressure rhodium carbonyl process" uses excess trialkylphosphine as a ligand with a concentration of 5%–15%. In this process, the n-isorhodium ratio of butyraldehyde is 6–10. To improve reaction selectivity and avoid the large-scale use of monophosphine ligands (such as PPh3), researchers have developed a series of ligands such as the Bisbi series, Xantphos series, and the Biphephos series with sterically hindered substituents. These ligands exhibit excellent activity and n-butyraldehyde selectivity in hydroformylation reactions. The high n-isorhodium ratio production process has resulted in increasingly less isobutyraldehyde produced as a byproduct. Furthermore, isobutyraldehyde is difficult to store and transport, which has significantly constrained the development of isobutyraldehyde and its downstream products.

[0005] For existing, mature olefin hydroformylation units, the NH / I ratio of the products can be altered by adjusting operating conditions. Using a mixture of bisphosphites and monophosphites as ligands is crucial. For example, patent CN201753511B reports a method to reduce or increase the NH / I ratio by increasing or decreasing the partial pressure of syngas in the first reaction zone; patent CN101657407B reports a method to reduce the NH / I ratio by reacting organic polyphosphites with water during the reaction, thereby decomposing the organic polyphosphite ligands and reducing their molar ratio with the transition metal; patent CN102741210B discloses a method to increase or decrease the NH / I ratio by increasing or decreasing the rhodium catalyst circulating liquid returned to the first reactor; and patent CN103951550B discloses a method to increase or decrease the NH / I ratio by increasing or decreasing the olefin concentration in the first reaction zone. However, these methods operate under special conditions and are difficult to maintain stable long-term operation of the unit.

[0006] To address the shortage of isobutyraldehyde raw materials, related research has been continuously pursued, resulting in a series of methods for synthesizing isobutyraldehyde. For example, CN 112169829 A discloses a bifunctional catalyst for the highly selective hydroformylation of propylene to produce isobutyraldehyde. This catalyst involves impregnating cobalt salt and a nitrogen-containing compound precursor into the pores of an acidic molecular sieve, followed by carbonization at a high temperature. This generates highly dispersed active cobalt carbide centers within the molecular sieve pores in situ, while simultaneously forming an N-modified carbon layer on the surface of the cobalt carbide. This method uses a fixed-bed reactor, achieving a propylene conversion rate of up to 89% and an isobutyraldehyde yield as high as 79%. However, the reaction temperature reaches 200℃, resulting in a relatively low overall propylene utilization rate.

[0007] CN 113416126 A discloses a method for the highly selective preparation of isobutyraldehyde by hydroformylation of propylene. The method designs a copper carbide bimetallic catalyst that can stabilize the presence of secondary carbocations. In this catalyst, CO is adsorbed on the catalyst, and copper carbide activates the carbonyl carbon and combines it with the secondary carbocations. Finally, the carbonyl carbon is released from the copper carbide and nickel to generate isobutyraldehyde.

[0008] CN 109675579 A discloses a method for preparing a catalyst for the synthesis of isobutyraldehyde from methanol and ethanol or propanol. The method involves dissolving a certain amount of vanadate, citric acid, and two or three of the following nitrates: Fe, Cu, Ni, Zr, Ca, and Ce, in an aqueous solution. The mixed solution is then evaporated to dryness in a constant-temperature water bath, followed by polar drying at 100-120℃ and calcination in a muffle furnace at 400-600℃ to prepare a solid catalyst with a unique V-Fe-MN structure (M is Cu or Ni, and N is one of Zr, Ca, and Ce). This catalyst exhibits excellent catalytic performance in the one-step synthesis of isobutyraldehyde from methanol and ethanol or propanol.

[0009] CN104321297A discloses a catalyst and method for improving selectivity for isobutyraldehyde through catalyst induction. In this method, supramolecular ligand assembly includes a tris(3-pyridyl)phosphine, a magnesium-centered tetraphenylporphyrin coordination complex, and a ligand formed in situ through the insertion of the first olefin into the carbonyl rhodium bond, forming a catalytic system that is more selective for branched aldehydes.

[0010] For existing, mature olefin hydroformylation units, the NH / I ratio of the products can be altered by adjusting operating conditions. Using a mixture of diphosphites and monophosphites as ligands is crucial. For example, patent CN201753511B discloses a method to reduce or increase the NH / I ratio by increasing or decreasing the partial pressure of syngas in the first reaction zone; patent CN101657407B discloses a method to reduce the NH / I ratio by reacting organic polyphosphites with water during the reaction, thereby decomposing the organic polyphosphite ligands and reducing their molar ratio with the transition metal; patent CN102741210B discloses a method to increase or decrease the NH / I ratio by increasing or decreasing the rhodium catalyst circulating liquid returned to the first reactor; and patent CN103951550B discloses a method to increase or decrease the NH / I ratio by increasing or decreasing the olefin concentration in the first reaction zone. However, these methods operate under special conditions and are difficult to maintain stable long-term operation of the unit.

[0011] In practice, the presence of trace amounts of water in the system can easily expose phosphite groups, leading to hydrolysis and reduced reaction efficiency. Simultaneously, hydrolysis byproducts can catalyze hydroformylation, reducing selectivity and increasing byproduct content. Patent CN1072691C uses organic amines and metal salts to improve the stability of the catalytic system, but this approach causes product condensation. CN103702758A uses epoxides to improve stability, but oxidation of the epoxides is difficult to prevent in actual operation. CN114057791A discloses a phosphite ligand with good hydrolysis resistance and high activity, but its structure is complex and its synthesis is challenging.

[0012] Therefore, developing methods or materials that can increase the production of isobutyraldehyde remains a key research focus in this field. Summary of the Invention

[0013] To address the shortcomings of existing technologies, the present invention aims to provide a hydrolysis-resistant catalyst for increasing the production of isobutyraldehyde through propylene hydroformylation and its application.

[0014] To achieve this objective, the present invention adopts the following technical solution:

[0015] On one hand, the present invention provides a hydrolysis-resistant catalyst for increasing the production of isobutyraldehyde through propylene hydroformylation, the catalyst comprising a ligand and a metal-centered compound, the ligand having the structure shown in Formula I:

[0016]

[0017] Wherein, P represents a phosphorus atom, and R1 to R6 are independently selected from H, halogen, C1-C4 (e.g., C1, C2, C3, or C4) alkyl, C1-C4 (e.g., C1, C2, C3, or C4) alkoxy, phenyl, trifluoromethyl, or trimethylsilyl.

[0018] The catalyst system described in this invention exhibits high hydrolysis resistance and stability. Starting from existing hydroformylation technology, this invention designs a catalyst composition containing a novel eight-membered ring phosphite ligand to adjust the selectivity of propylene hydroformylation. The positive-to-isobutyraldehyde ratio can reach 1.0–1.1:1, significantly increasing the yield of isobutyraldehyde. More importantly, the phosphorus atom in this composition bonds with a sterically hindered ortho-bisphenol compound, forming a highly hydrophobic eight-membered intracyclic phosphite, restricting the intrusion of water molecules, significantly improving hydrolysis resistance, and exhibiting long-term activity. This catalytic system can be used to upgrade existing butanol and octanol industrial plants to increase the yield of isobutyraldehyde.

[0019] In this invention, unless otherwise stated, halogen means a halogenated element throughout, and may be, for example, F, Cl, Br or I; unless otherwise stated, C1-C4 alkyl means a branched or straight alkyl group having 1-4 carbon atoms, and may be, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl; unless otherwise stated, C1-C4 alkoxy means a group formed by attaching a "C1-C4 alkyl" to an O atom.

[0020] Preferably, the ligand is any one of the following ligands L1-L12:

[0021]

[0022]

[0023] Preferably, the metal center compound includes an iron compound, a cobalt compound, a nickel compound, a ruthenium compound, a rhodium compound, an iridium compound, or a palladium compound. Cobalt compounds or rhodium compounds are preferred, and rhodium compounds are even more preferred.

[0024] Preferably, the rhodium compound is selected from rhodium ethyl acetate (Rh(OAc)3), rhodium acetylacetone dicarbonyl acetate (Rhacac(CO)2), and rhodium carbonyl (Rh4(CO)3). 12Rhodium ethyl acetate of 1,5-cyclooctadiene ([Rh(OAc)(COD)]2), phosphoramidite carbonyl rhodium or acetylacetone phosphoramidite carbonyl rhodium, or any one or a combination of at least two of these.

[0025] Preferably, the molar ratio of the ligand and the metal atoms in the metal center compound is 1 to 10:1, for example 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, preferably 2 to 8:1.

[0026] On the other hand, the present invention provides a method for increasing the production of isobutyraldehyde by hydroformylation of propylene, the method comprising reacting propylene with syngas under the catalysis of the catalyst described above to obtain isobutyraldehyde.

[0027] Preferably, the specific operation of the reaction is as follows: dissolving the catalyst as described above in a solvent to prepare a catalyst solution, adding propylene and synthesis gas to the catalyst solution, and reacting to obtain isobutyraldehyde.

[0028] Preferably, the concentration of the ligand in the catalyst solution is 50 to 1800 ppm, for example 50 ppm, 80 ppm, 100 ppm, 300 ppm, 500 ppm, 700 ppm, 900 ppm, 1000 ppm, 1300 ppm, 1500 ppm or 1800 ppm, and the preferred ligand concentration is 200 to 1200 ppm.

[0029] Preferably, the molar ratio of carbon monoxide to hydrogen in the synthesis gas is 0.5 to 2:1, for example, 0.5:1, 0.8:1, 1:1, 1.3:1, 1.5:1, 1.8:1 or 2:1, and more preferably, the molar ratio of carbon monoxide to hydrogen is 0.9 to 1.3:1.

[0030] Preferably, the reaction temperature is 65–100°C, for example 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, with a preferred reaction temperature of 70–85°C.

[0031] Preferably, the reaction pressure is 0.8 to 3.0 MPa, for example 0.8 MPa, 1.0 MPa, 1.5 MPa, 1.8 MPa, 2.0 MPa, 2.3 MPa, 2.5 MPa, 2.8 MPa or 3.0 MPa, and more preferably 1.0 to 2.3 MPa.

[0032] Preferably, the reaction time is 0.5-10h, for example 0.5h, 0.8h, 1h, 3h, 5h, 8h or 10h.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The catalyst of this invention is used to catalyze the reaction of propylene with syngas. It exhibits high reactivity, good selectivity, low metal catalyst dosage, and high propylene conversion rate. The isobutyraldehyde ratio can reach 1.0–1.1:1, thus achieving the goal of increasing isobutyraldehyde production. Furthermore, the catalyst used in this method is highly stable and can be reused multiple times. Even after repeated use, it maintains a low isobutyraldehyde ratio, high conversion rate, and low hydrolysis rate. This method can be used to upgrade existing butanol and octanol industrial plants to increase isobutyraldehyde production. Detailed Implementation

[0035] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0036] Examples 1-5

[0037] [Rh(acac)(CO)2] (0.01 mmol), the phosphite ligand specified in Table 1 (0.04 mmol), and 50 mL of anhydrous toluene were added to a 300 mL stainless steel autoclave. The gas inside the autoclave was purged three times with nitrogen. 20 g of propylene was added, and a mixed gas (H2:CO = 1:1, partial pressure 1.5 MPa) was introduced. The autoclave was heated to 75 °C with stirring, and gas was added during the reaction. After the specified reaction time, the autoclave was cooled and depressurized. The contents of the autoclave were weighed, and a sample was taken for gas chromatography (GC) to determine the molar ratio of n-butyraldehyde to isobutyraldehyde. The results are listed in Table 1.

[0038] Comparative Example 1

[0039] Add 0.01 mmol of [Rh(acac)(CO)2] and 50 mL of anhydrous toluene to a 300 mL stainless steel autoclave. Replace the gas in the autoclave three times with nitrogen. Add 20 g of propylene and purge with a mixed gas (H2:CO = 1:1, partial pressure 1.5 MPa). Heat to 75 °C with stirring, adding gas as needed during the reaction. After the specified reaction time, cool and depressurize, open the autoclave, weigh, and take a sample for gas chromatography (GC) to determine the molar ratio (n-butyraldehyde / isobutyraldehyde).

[0040] Table 1 Effect of different conditions on the selectivity of propylene hydroformylation

[0041]

[0042] Example 6

[0043] [Rh(acac)(CO)2] (0.01 mmol), phosphite ligand L9 (0.04 mmol), and 50 mL of anhydrous toluene were added to a 300 mL stainless steel autoclave equipped with a pressure gauge under an air atmosphere. The gas in the autoclave was purged three times with nitrogen, and 20 g of olefin (Table 2) was added. A mixed gas (H2:CO = 1:1, partial pressure 1.5 MPa) was introduced. The mixture was heated to 75 °C with stirring, and gas was added during the reaction. After the specified reaction time, the autoclave was cooled and depressurized, the contents were opened and weighed, and a sample was taken for gas chromatography (GC) to determine the molar ratio of n-butyraldehyde to isobutyraldehyde. The results are listed in Table 2.

[0044] Table 2. Effect of catalytic system on the selectivity of hydroformylation of different olefins

[0045] Olefins reaction temperature time Positive and negative ratio 1 1-Butene 80 8 1.72 2 1-Butene 85 8 0.61 3 Isobutylene 85 8 --

[0046] The hydroformylation product of isobutene is only isopentanal, not n-pentanal, so there is no concept of an isopentanal-to-isobutanal ratio. As shown in the table above, the catalytic system provided by this invention can also be used for the hydroformylation reaction of butene.

[0047] Example 7

[0048] Using L9 ligand and following the reaction conditions in the examples, after the reaction was completed, only the product butyraldehyde was removed by distillation. The reaction solution was then re-introduced with propylene and syngas for a cyclic reaction. The results are shown in Table 3.

[0049] Table 3

[0050] Loop count Water content % Conversion rate % Positive and negative ratio Hydrolysis rate % 5 0.2 99 1.01 0.04 10 0.3 98 1.10 0.06 15 0.5 98 1.08 0.09

[0051] As can be seen from Table 3, after multiple cycles, the conversion rate and the ratio of positive to negative of ligand L9 only changed significantly, while the water content and hydrolysis rate did not increase significantly. This indicates that ligand L9 has very good hydrolysis resistance.

[0052] Using L10 ligand and following the reaction conditions in the examples, after the reaction was completed, only the product butyraldehyde was removed by distillation. The reaction solution was then re-introduced with propylene and synthesis gas for a cyclic reaction. The results are shown in Table 4.

[0053] Table 4

[0054] Loop count Water content % Conversion rate % Positive and negative ratio Hydrolysis rate % 5 0.2 98 1.02 0.02 10 0.2 99 1.08 0.05 15 0.5 99 1.12 0.08

[0055] After multiple cycles, the conversion rate and the ratio of positive to negative of ligand L10 showed no significant changes, while the water content and hydrolysis rate did not show significant increases, indicating that ligand L10 has very good hydrolysis resistance.

[0056] Comparative Example 2

[0057] Referring to Example 7, the ligand was replaced with triphenyl phosphite. The test results showed a conversion rate of 97% and an isotropic ratio of 1.3. After 5 cycles, the water content was 0.2%, the conversion rate was 50%, the isotropic ratio was 4, and the hydrolysis rate was 16.42%.

[0058] Example 8

[0059] L9 ligand and triphenyl phosphite ligand were dissolved in butyraldehyde to prepare 500 ppm solutions, which were then stirred at 75 °C. The water content and ligand hydrolysis rate were measured at specific time intervals, as shown in Table 5.

[0060] Table 5

[0061]

[0062] As shown in Table 5, compared with existing triphenyl phosphites, the L9 ligand containing an eight-membered ring has a lower water content and hydrolysis rate. This is because the phosphorus atom bonds with the sterically hindered ortho-bisphenol compound to form a highly hydrophobic eight-membered intracyclic phosphite, which restricts the intrusion of water molecules and significantly improves the resistance to hydrolysis.

[0063] The applicant declares that this invention illustrates the hydrolysis-resistant propylene hydroformylation catalyst for increasing isobutyraldehyde production and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product, addition of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. A hydrolysis-resistant catalyst for increasing the production of isobutyraldehyde through propylene hydroformylation, characterized in that, The catalyst comprises a ligand and a metal-centered compound, wherein the ligand is any one of the following ligands L1-L12: 。 2. The hydrolysis-resistant catalyst for increasing the production of isobutyraldehyde through propylene hydroformylation according to claim 1, characterized in that, The metal-centered compound includes iron compounds, cobalt compounds, nickel compounds, ruthenium compounds, rhodium compounds, iridium compounds, or palladium compounds.

3. The hydrolysis-resistant catalyst for increasing the production of isobutyraldehyde through propylene hydroformylation according to claim 2, characterized in that, The metal center compound is a cobalt compound or a rhodium compound.

4. The hydrolysis-resistant catalyst for increasing the production of isobutyraldehyde through propylene hydroformylation according to claim 3, characterized in that, The metal center compound is a rhodium compound.

5. The hydrolysis-resistant catalyst for increasing the production of isobutyraldehyde through propylene hydroformylation according to claim 4, characterized in that, The rhodium compound is selected from any one or a combination of at least two of the following: rhodium ethyl acetate, rhodium acetylacetone dicarbonyl acetate, rhodium carbonyl, rhodium 1,5-cyclooctadiene ethyl acetate, rhodium phosphorusamide carbonyl, or rhodium acetylacetone phosphorusamide carbonyl.

6. The hydrolysis-resistant catalyst for increasing the production of isobutyraldehyde through propylene hydroformylation according to claim 1, characterized in that, The molar ratio of metal atoms in the ligand and the metal center compound is 1 to 10:

1.

7. The hydrolysis-resistant catalyst for increasing the production of isobutyraldehyde through propylene hydroformylation according to claim 6, characterized in that, The molar ratio of metal atoms in the ligand and the metal center compound is 2~8:

1.

8. A method for increasing the production of isobutyraldehyde by hydroformylation of propylene, the method comprising reacting propylene with syngas under the catalysis of any one of claims 1-7 to obtain isobutyraldehyde.

9. The method according to claim 8, characterized in that, The specific operation of the reaction is as follows: the catalyst is dissolved in a solvent to prepare a catalyst solution, propylene and synthesis gas are added to the catalyst solution, and isobutyraldehyde is obtained by reaction.

10. The method according to claim 8, characterized in that, The concentration of ligands in the catalyst solution is 50~1800 ppm.

11. The method according to claim 10, characterized in that, The concentration of ligands in the catalyst solution is 200~1200 ppm.

12. The method according to claim 8, characterized in that, The molar ratio of carbon monoxide to hydrogen in the synthesis gas is 0.5 to 2:

1.

13. The method according to claim 12, characterized in that, The molar ratio of carbon monoxide to hydrogen in the synthesis gas is 0.9~1.3:

1.

14. The method according to claim 8, characterized in that, The reaction temperature is 65~100℃.

15. The method according to claim 14, characterized in that, The reaction temperature is 70~85℃.

16. The method according to claim 8, characterized in that, The reaction pressure is 0.8~3.0 MPa.

17. The method according to claim 16, characterized in that, The reaction pressure is 1.0~2.3 MPa.

18. The method according to claim 8, characterized in that, The reaction time is 0.5-10 hours.

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