Preparation method and application of catalyst for catalyzing hydroformylation of alpha-olefin to synthesize linear aldehyde

Abstract

The invention discloses a preparation method and application of a catalyst for catalyzing hydroformylation of alpha-olefin to synthesize linear aldehyde. The preparation method comprises the following steps: firstly, adding an Rh-en and Co-en complex solution formed by RhCl3. 3H2O, Co (NO3) 2.6 H2O and ethylenediamine (EDA) into a mixed solution formed by GeO2, tetrapropylammonium hydroxide (TPAOH) and H2O, and uniformly stirring and mixing; then, tetraethoxysilane is added into the mixed solution, and stirring is conducted for 6 h at the room temperature; and then, crystallizing the mixture at 170 DEG C, and roasting in air at 550 DEG C for 6 hours to prepare the Co3Rh1-coated Ge-S-1 catalyst. The Co3Rh1 and Ge-S-1 catalyst and alpha-olefin are added into a high-pressure reaction kettle, CO / H2 mixed gas (V: V, 1: 1) is introduced, and reaction is performed for 6-10 h at 80-120 DEG C. The conversion rate of the alpha-olefin is as high as 97.9%, the selectivity of linear aldehyde is as high as 96.9%, the catalyst still keeps activity after multiple cycles, and Co / Rh active components are not lost. According to the method, the preparation method of the Co3Rh1-coated Ge-S-1 catalyst is simple, the Co3Rh1-coated Ge-S-1 catalyst can keep high catalytic activity and stability in catalysis of alpha-olefin hydroformylation for synthesis of linear aldehyde, and the Co3Rh1-coated Ge-S-1 catalyst is easy for industrial production and conversion.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fine chemical industry, in particular to a preparation method of a catalyst for catalyzing the synthesis of linear aldehyde by hydroformylation of α-olefin and application thereof. BACKGROUND

[0002] Catalytic hydroformylation is an important reaction in chemical industry that converts olefins and syngas (CO / H2) into high-value aldehyde chemicals, with 100% atom economy, and is widely used in the synthesis of fine chemicals, pharmaceuticals and plastic intermediates (Chemical Reviews, 2012, 112(11), 5675-5732). More than 24 million tons of aldehyde compounds are produced annually worldwide through the olefin hydroformylation reaction, among which linear aldehydes (such as n-butyraldehyde, n-pentanal) are more valuable due to their wide application in downstream fields (J. Am. Chem. Soc., 2023, 145(5), 2911-2929). Although traditional homogeneous hydroformylation catalysts such as rhodium-phosphine complexes have high activity and linear aldehyde selectivity, the reaction still faces challenges such as difficulty in selectivity control, high cost of catalyst recovery, metal loss and phosphine ligand pollution of the environment (Angew. Chem. Int. Ed., 2013, 52, 2852-2872). Therefore, the development of efficient and stable heterogeneous catalysts has become a research hotspot. Heterogeneous catalysts anchor active metals on solid supports, achieving easy separation and recycling of catalysts, but early heterogeneous catalysts (such as Rh / SiO2, Rh / Al2O3) often have decreased activity and insufficient selectivity due to metal sintering and low dispersion.

[0003] Zeolite molecular sieves are widely used as supports for heterogeneous catalysts due to their regular pore structure, high specific surface area and adjustable acidity. Among them, Silicalite-1 (S-1) as a full-silicon MFI type zeolite has hydrophobicity and good thermal stability, which is suitable for coating metal active sites to form an "inorganic ligand" microenvironment, achieving high metal dispersion and selectivity. For example, the Rh@S-1 catalyst reported in the literature shows a high linear aldehyde selectivity of up to 970 mol molRh -1 h -1The high propionaldehyde yield of the catalyst is attributed to the enrichment effect of zeolite channels on the gaseous reactants, which significantly improves the reaction rate, highlighting the promotion of zeolite microenvironment on reaction kinetics (J. Am. Chem. Soc., 2025, 147(13), 11301-11308). In recent years, chemical modification of zeolites has become a key strategy to optimize the microenvironment of catalysts. Germanium (Ge)-modified MFI zeolites (Ge-MFI) can enhance metal-support interactions and stabilize highly dispersed metal sites by introducing Ge atoms to modify the electronic properties of the zeolite framework. Studies have shown that Ge species can effectively anchor metals such as Pt and Rh, forming anti-sintering structures. For example, the Pt / Ge-MFI catalyst reported in the literature exhibits excellent self-regeneration ability in the propane dehydrogenation reaction, with no change in activity after 110 cycles, due to the dynamic stabilization of Pt clusters by Ge sites (Science, 2025, 388, 497-502). Extending this strategy to hydroformylation reactions, Ge-modified S-1 molecular sieve-coated Rh metal catalysts are expected to achieve high linear aldehyde selectivity.

[0004] Bimetallic synergistic effect is another key factor in improving the performance of hydroformylation. Cobalt and rhodium form alloys or single-atom sites, which can adjust the adsorption energy of CO and H2, promote the hydrogenation of acyl intermediates, and thus enhance the selectivity of linear aldehydes. A multi-component synergistic catalyst Co@N-CNTs|RhP significantly reduces the activation energy of olefin hydroformylation reaction through synergistic catalysis. In the hydroformylation of diisobutylene, this catalyst achieves 100% conversion and 94% aldehyde selectivity, with a turnover frequency of 82603 h -1 , which is 15 times the activity of traditional Wilkinson catalysts (ACS Catal., 2025, 15(2), 1399-1410). Studies have found that in the Rh1Co SAA / N-C catalyst, there is a multi-step synergistic catalytic mechanism: H2 molecules preferentially dissociate on Co sites to form Co-H species, while CO adsorbs and inserts into Co sites, thereby promoting the C-C coupling reaction; while the adjacent Rh-Co double sites effectively stabilize the 1-hexene reaction intermediate through synergistic adsorption, improving reaction efficiency (AIChE J., 2025, 71(6), e18798). In addition, the confinement effect of zeolites can inhibit olefin isomerization and hydrogenation side reactions. For example, Rh clusters encapsulated in MFI sinusoidal channels exhibit about 90% chemical selectivity for the hydroformylation of C6-C12 linear alpha-olefins. Although zeolite molecular sieves have made great progress as support materials in olefin hydroformylation research, current studies have mostly focused on single-metal systems (such as Rh or Co), and there is still a need to develop efficient bimetallic site synergistic olefin hydroformylation catalysts to achieve high-selectivity hydroformylation of alpha-olefins to linear aldehydes. SUMMARY

[0005] To solve the problems in the synthesis of linear aldehydes by the aforementioned α-olefin hydroformylation, the present application provides a preparation method of a Co / Rh bimetallic site catalyst (Co3Rh1@Ge-S-1) encapsulated by Ge-modified S-1 molecular sieve; and using the prepared catalyst, a method for the high-selectivity synthesis of linear aldehydes by catalyzing the hydroformylation of linear α-olefins (for example, the hydroformylation of 1-hexene, see the following formula).

[0006]

[0007] To solve the technical problems of the present application, the following technical solutions are adopted:

[0008] A preparation method of a catalyst for the synthesis of linear aldehydes by catalyzing the hydroformylation of α-olefins and the application thereof, the preparation method of the Co3Rh1@Ge-S-1 catalyst is as follows: first, RhCl3·3H2O and Co(NO3)2·6H2O are mixed with ethylenediamine (EDA) to form a precursor solution, and deionized water is added, and then the mixture is subjected to ultrasonic treatment for 10 min to obtain Rh-en and Co-en complex solutions; then, GeO2 is mixed with tetrapropylammonium hydroxide (TPAOH) and H2O, and after stirring at room temperature for 30 min, the prepared Rh-en and Co-en complex solutions are added (mol Co / mol Rh = 3:1), and stirring is continued for another 30 min; then, tetraethyl orthosilicate is added to the mixed solution, and stirring is continued at room temperature for 6 h; subsequently, the mixture is transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reaction kettle, and crystallization is carried out at 170℃ for 72 h; after the reaction is completed, the solid precipitate is collected by centrifugation, and is washed with deionized water and anhydrous ethanol multiple times, and is dried, and then is calcined in a muffle furnace at 550℃ for 6 h. Finally, the Co3Rh1@Ge-S-1 catalyst is obtained.

[0009] The support material used in the prepared Co3Rh1@Ge-S-1 catalyst is Ge-modified S-1 zeolite, which has a rich microporous structure and Ge-modified sites, can efficiently adsorb Rh-en and Co-en complexes, and through high-temperature calcination, the Co3Rh1@Ge-S-1 catalyst is prepared.

[0010] The prepared Co3Rh1@Ge-S-1 catalyst has a high specific surface area, excellent stability and a hierarchical pore structure; the specific surface area of the Ge-S-1 support is 348 m 2 ·g -1 , and the average pore size is 0.73 nm; the specific surface area of the Co3Rh1@Ge-S-1 catalyst is 331 m 2 ·g -1The average pore size is 0.67 nm.

[0011] The prepared Co3Rh1@Ge-S-1 catalyst has Co3Rh1 active sites which are highly dispersed and embedded in the Ge-S-1 channel, effectively preventing the loss of Rh active sites.

[0012] The mass ratio of metal to carrier in the prepared Co3Rh1@Ge-S-1 catalyst is Rh:Co:Ge-S-1 = 0.0028:0.0048:1.

[0013] The Co3Rh1@Ge-S-1 catalyst is used in the hydroformylation of alpha-olefins, and the hydroformylation of 1-hexene is used as a probe reaction, and the specific method is as follows: 30 mg of catalyst, 0.5 mmol of 1-hexene and 4 mL of solvent are sequentially added into a 50 mL high-pressure reaction kettle; then, the reaction kettle is purged with CO / H2 (1:1) mixed gas three times at room temperature to replace air, and then the synthesis gas is filled to the specified pressure; the reaction kettle is heated to the set reaction temperature and kept for a certain time; after the reaction is completed, the reaction kettle is cooled to room temperature, the residual gas is released to normal pressure, and the catalyst is recovered by filtration; gas chromatography is used to analyze the conversion rate of 1-hexene and the selectivity of the product, and the conversion rate of 1-hexene is as high as 97.9%, and the selectivity of 1-heptanal is as high as 96.9%.

[0014] The gas pressure of the hydroformylation reaction of alpha-olefins is 1.0-3.0 MPa, the reaction temperature is 80-120 DEG C, and the reaction time is 6-10 hours.

[0015] In the hydroformylation reaction of alpha-olefins, the Co3Rh1@Ge-S-1 catalyst can be recycled for 6 times, and still maintains stable catalytic activity and linear aldehyde selectivity.

[0016] The advantages of the present application are: 1. The Ge modified S-1 molecular sieve encapsulated Co / Rh bimetallic site catalyst Co3Rh1@Ge-S-1 designed and prepared in the present application adopts an in-situ self-assembly synthesis method of adding Rh and Co complex in the synthesis process of Ge-S-1 molecular sieve, and the catalyst preparation method is simple, the conditions are mild, and the catalyst is easy to scale up. 2. The Co / Rh bimetallic site in the Ge-S-1 catalyst is highly dispersed and encapsulated in the Ge-S-1 channel structure, and the catalyst has excellent stability, can be recycled for 6 times, and still has very high activity, and there is no Rh loss. 3. The Co3Rh1@Ge-S-1 catalyst provided in the present application has high alpha-olefin conversion rate and product linear aldehyde yield in the catalytic hydroformylation reaction of alpha-olefins, and the reaction operation is simple, easy to control, easy to industrialize and scale up. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1Scanning electron microscope images of Ge-S-1 support (a), Co3Rh1@Ge-S-1 catalyst (b) prepared in Example 1 of the present application, transmission electron microscope images of Ge-S-1 support (c), Co3Rh1@Ge-S-1 catalyst (d).

[0018] Figure 2 XRD patterns of Ge-S-1 support (a), Co3Rh1@Ge-S-1 catalyst (b) prepared in Example 1 of the present application.

[0019] Figure 3 N2 adsorption-desorption curves and pore size distribution curves of Ge-S-1 support (a), Co3Rh1@Ge-S-1 catalyst (b) prepared in Example 1 of the present application.

[0020] Figure 4 Cyclic use effect diagram of Co3Rh1@Ge-S-1 catalyst prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0021] Example 1

[0022] A preparation method of a catalyst for catalyzing α-olefin hydroformylation to synthesize linear aldehyde and application thereof, the specific method is as follows: first, 24.1 mg of RhCl3·3H2O and 80.0 mg of Co(NO3)2·6H2O are mixed with 0.6 mL of ethylenediamine to form a precursor solution, and 0.6 mL of deionized water is added, and the mixture is ultrasonically treated for 10 min to obtain Rh-en and Co-en complex solutions; then, 15.2 mg of GeO2 is mixed with 13 g of TPAOH and 19.875 g of H2O, and after stirring at room temperature for 30 min, the prepared Rh-en and Co-en complex solutions (mol Co / mol Rh = 3:1) are added at the same time, and then stirred for 30 min; then, 8.32 g of tetraethyl orthosilicate is added to the mixed solution, and stirred at room temperature for 6 h, and the mixture is transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reaction kettle, and crystallized at 170 ℃ for 72 h; after crystallization, the solid precipitate is collected by centrifugation, and washed with deionized water and anhydrous ethanol several times in turn, and dried, and then calcined in a muffle furnace at 550 ℃ for 6 h to obtain a Co3Rh1@Ge-S-1 catalyst, the Rh content in the catalyst is 0.28%, and the Co content is 0.48%.

[0023] Example 2

[0024] A preparation method of a catalyst for catalyzing α-olefin hydroformylation to synthesize linear aldehyde and application thereof, the specific method is as follows: 30 mg of Co3Rh1@Ge-S-1 catalyst in example 1, 0.5 mmol of 1-hexene and 4 mL of toluene solvent are added into a high-pressure reaction kettle, 2 MPa of CO / H2 mixed gas (V:V, 1:1) is filled, and reaction is carried out at 100 ℃ for 8 h, and 1-hexene conversion rate is as high as 97.9% and 1-heptanal selectivity is as high as 96.9% detected by gas chromatography analysis.

[0025] Example 3-11

[0026] A preparation method of a catalyst for catalyzing α-olefin hydroformylation to synthesize linear aldehyde and application thereof, the specific method is as follows: according to the method in example 2, 30 mg of Co3Rh1@Ge-S-1 catalyst in example 1, 0.5 mmol of α-olefin compound and 4 mL of toluene solvent are added into a 50 mL high-pressure reaction kettle, 2 MPa of CO / H2 mixed gas (V:V, 1:1) is filled, and reaction is carried out at 100 ℃ for 8 h, and α-olefin conversion rate and linear aldehyde selectivity are shown in the following table (table 1), Co3Rh1@Ge-S-1 catalyst has good linear aldehyde selectivity in catalyzing different α-olefin hydroformylation.

[0027] Table 1. Reaction results of Co3Rh1@Ge-S-1 catalyst in catalyzing different α-olefin hydroformylation to synthesize linear aldehyde.

[0028]

[0029] Example 12

[0030] A preparation method of a catalyst for catalyzing α-olefin hydroformylation to synthesize linear aldehyde and application thereof, the specific method is as follows: after Co3Rh1@Ge-S-1 catalyst in example 2 is filtered and washed, 0.5 mmol of 1-hexene and 4 mL of toluene solvent are added into a 50 mL high-pressure reaction kettle, 2 MPa of CO / H2 mixed gas (V:V, 1:1) is filled, and reaction is carried out at 100 ℃ for 8 h, and Co3Rh1@Ge-S-1 catalyst is used for 6 times, 1-hexene conversion rate is higher than 92%, linear aldehyde selectivity is higher than 94%, Rh content is detected by ICP, and no Co / Rh active site loss is found.

Claims

1. A method for preparing a catalyst for the hydroformylation of α-olefins to synthesize linear aldehydes and its application, characterized in that: First, RhCl3·3H2O and Co(NO3)2·6H2O were mixed with ethylenediamine (EDA) to form precursor solutions, and deionized water was added. The mixture was then sonicated for 10 min to obtain Rh-en and Co-en complex solutions. Next, GeO2 was mixed with tetrapropylammonium hydroxide (TPAOH) and H2O, stirred at room temperature for 30 min, and then the prepared Rh-en and Co-en complex solutions (mol) were added simultaneously. Co / mol Rh =3:1), and stirred for 30 min; then, tetraethyl orthosilicate was added to the mixed solution and stirred at room temperature for 6 h; subsequently, the mixture was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor and crystallized at 170 °C for 72 h; after the reaction was completed, the solid precipitate was collected by centrifugation and washed repeatedly with deionized water and anhydrous ethanol, dried, and calcined in a muffle furnace at 550 °C for 6 h to obtain the Co3Rh1@Ge-S-1 catalyst.

2. The preparation method and application of the catalyst for the hydroformylation of α-olefins to synthesize linear aldehydes according to claim 1, characterized in that: The Co3Rh1@Ge-S-1 catalyst prepared using Ge-modified S-1 zeolite as the support material has abundant microporous structure and Ge-modified sites, which can efficiently adsorb Rh-en and Co-en complexes. The Co3Rh1@Ge-S-1 catalyst is obtained by high-temperature calcination.

3. The preparation method and application of the catalyst for the hydroformylation of α-olefins to synthesize linear aldehydes according to claim 1, characterized in that: The prepared Co3Rh1@Ge-S-1 catalyst exhibits high specific surface area, excellent stability, and a hierarchical porous structure. The Co3Rh1 active sites are highly dispersed and embedded within the Ge-S-1 channels, effectively preventing the loss of Rh active sites. The specific surface area of ​​the Ge-S-1 support is 348 m². 2 ·g -1 The average pore size is 0.73 nm; the specific surface area of ​​the Co3Rh1@Ge-S-1 catalyst is 331 m². 2 ·g -1 The average pore size is 0.67 nm.

4. The preparation method and application of the catalyst for the hydroformylation of α-olefins to synthesize linear aldehydes according to claim 1, characterized in that: The mass ratio of metal to support in the prepared Co3Rh1@Ge-S-1 catalyst is Rh:Co:Ge-S-1 = 0.0028:0.0048:

1.

5. The preparation method and application of the catalyst for the hydroformylation of α-olefins to synthesize linear aldehydes according to claim 1, characterized in that: The Co3Rh1@Ge-S-1 catalyst was used for the hydroformylation of 1-hexene. 30 mg of catalyst, 0.5 mmol of 1-hexene, and 4 mL of solvent were sequentially added to a 50 mL high-pressure reactor. Subsequently, the reactor was purged three times at room temperature using a CO / H2 (1:1) mixture, and then syngas was introduced to the specified pressure. The reactor was heated to the set reaction temperature and maintained for a certain time. After the reaction, the reactor was cooled to room temperature, and the residual gas was released to atmospheric pressure. The catalyst was recovered by filtration. Gas chromatography analysis of the 1-hexene conversion and product selectivity showed a 1-hexene conversion of up to 97.9% and a 1-heptanal selectivity of up to 96.9%.

6. The preparation method and application of the catalyst for the catalytic hydroformylation of α-olefins to synthesize linear aldehydes according to claim 1, characterized in that: The gas pressure for the hydroformylation reaction of α-olefins is 1.0-3.0 MPa, the reaction temperature is 80-120℃, and the reaction time is 6-10 hours.

7. The preparation method and application of the catalyst for the hydroformylation of α-olefins to synthesize linear aldehydes according to claims 1 and 5, characterized in that: The Co3Rh1@Ge-S-1 catalyst can be recycled up to 6 times for the hydroformylation reaction of the α-olefins, and still maintains high catalytic activity. The conversion rate of 1-hexene is higher than 92%, and the selectivity of linear aldehydes is higher than 94%. No loss of Co / Rh active sites was observed.

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