Cobalt-based catalyst for olefin hydroformylation reaction as well as preparation and application of cobalt-based catalyst

Abstract

The invention discloses a cobalt-based catalyst for olefin hydroformylation reaction as well as preparation and application thereof. The method comprises the following steps: adding a precipitator into a cobalt salt solution, carrying out hydrothermal treatment at 150-180 DEG C, centrifuging, washing and drying, and calcining at 200-500 DEG C; and putting the mixture in reducing gas flow at 200-300 DEG C for reduction to obtain the high-valence cobalt catalyst. Or / and reducing the Co3O4 precursor in reducing gas flow at the temperature of 300-450 DEG C to obtain the low-valence cobalt catalyst. The method solves the problems that the prior art depends on complex ligands / bimetals, the regulation dimension is single, the condition is harsh, the universality is poor, and high selectivity, high stability and wide substrate adaptation are difficult to meet at the same time, and the catalyst taking Co < 2 + > / Co < 3 + > as a main component can enable the alcohol selectivity of olefin hydroformylation reaction to reach 90% or above. The low-valence catalyst taking Co0 as a main component can enable the aldehyde selectivity to reach 90% or above.

Description

Technical Field

[0001] This invention relates to a method for selective catalysis of olefin hydroformylation, specifically to a cobalt-based catalyst for olefin hydroformylation reaction and its preparation and application. Background Technology

[0002] Olefin hydroformylation is a core catalytic process in the industrial production of high-value oxygen-containing compounds (such as plasticizers, surfactants, fragrances, and pharmaceutical intermediates). The aldehyde product can be used directly as the target product or further hydrogenated to form an alcohol. Therefore, precisely controlling the aldehyde / alcohol selectivity of the hydroformylation reaction is crucial for achieving targeted product synthesis, optimizing process flow, and improving economic efficiency; it also represents a core technological challenge in this field.

[0003] Existing strategies for controlling the selectivity of aldehydes / alcohols mainly fall into two categories: one is catalyst design optimization, including ligand chemical modification, screening of active metal components, and ratio control; the other is reaction process parameter control, including dynamic adjustment of reaction temperature and pressure, and optimization of the H2 / CO gas ratio. However, all of the above strategies have significant limitations: regarding ligand modification, although methylated ligand catalysts can improve alcohol selectivity, rhodium loss occurs after multiple reaction cycles, leading to a decrease in selectivity; regarding bimetallic catalysts, although the Rh-Ru system can promote aldehyde hydrogenation, it suffers from poor substrate selectivity, numerous side reactions, and high cost; regarding process parameter control, the temperature control method for single-atom cobalt catalysts has a narrow control range, and the parameter adjustment range of CoZrP catalysts is limited and easily affects catalyst stability.

[0004] Existing document 1 (Chinese invention patent application with authorization number CN105712852B) discloses a method for highly selective preparation of n-aldehydes via two-phase hydroformylation of olefins based on polyether quaternary ammonium salt ionic liquids. This method focuses on the highly selective preparation of n-aldehydes and constructs a two-phase catalytic system consisting of a polyether quaternary ammonium salt ionic liquid and an organic phase. A rhodium catalyst is used as the core, combined with specific bisphosphine ligands. The ionic liquid phase supports the rhodium catalyst, and the organic phase is C3-C. 10 Straight-chain 1-olefins and reaction products; reaction temperature 70℃~130℃, syngas pressure 1MPa~10MPa; rhodium catalyst recovered after reaction via two-phase separation. This system achieves 96%~97% regioselectivity for n-aldehydes with rhodium loss as low as 0.05%~0.1%. This technology focuses only on improving the selectivity of n-aldehydes and does not involve selective control of aldehyde-to-alcohol conversion. Essentially, it reduces rhodium loss and improves aldehyde selectivity through ligand and ionic liquid system optimization, rather than controlling product orientation through the inherent characteristics of the catalyst. Furthermore, its catalytic system is only suitable for C3-C reactions. 10Linear 1-olefins lack universality. Reference 2 (Chinese invention patent application CN104591960B) discloses a heterogeneous catalytic method and apparatus for the hydroformylation of olefins to synthesize aldehydes and alcohols. Addressing the difficulty of separating catalysts from products in homogeneous catalysis, a heterogeneous catalytic scheme is proposed. It uses a Co₂C and metal Co complex supported on activated carbon as the main active component catalyst, with one or more of Cu, La, etc., as promoters. The weight content of Co₂C in the catalyst is adjusted from 40% to 75% to meet the CO insertion performance requirements of olefin hydroformylation. Reaction conditions are controlled at pressure 0.1 MPa to 10.0 MPa, temperature 433 K to 503 K, and a H₂ to CO molar ratio in the syngas of (0.1 to 5): 1. A fixed-bed reactor is used to achieve a continuous production mode with continuous feeding of olefins and syngas and continuous product outflow, thereby simplifying the product-catalyst separation process. It adjusts catalytic performance by controlling the crystal phase ratio of Co₂C to metal Co, but does not address the control of the valence state of the active species in the catalyst. This control method is limited to the crystal phase ratio of cobalt-based catalysts and cannot flexibly adapt to the selectivity requirements of aldehydes or alcohols at different reaction stages through inherent characteristics. Moreover, in long-term cyclic reactions, the crystal phase ratio is prone to change due to fluctuations in the reaction environment, which in turn affects the selectivity stability of aldehydes / alcohols. Summary of the Invention

[0005] The purpose of this invention is to provide a cobalt-based catalyst for the hydroformylation of olefins, its preparation, and its application. This invention solves the problems of existing technologies, such as reliance on complex ligands / bimetals, limited control dimensions, stringent conditions, poor universality, and difficulty in simultaneously achieving high selectivity, high stability, and broad substrate compatibility. By controlling the catalyst reduction conditions, the valence state distribution of cobalt active species in the catalyst is adjusted, using Co... 2+ / Co 3+ The catalyst, primarily Co, can achieve an alcohol selectivity of over 90% in the hydroformylation of olefins. 0 The low-valence catalyst, which is mainly composed of aldehydes, can achieve a selectivity of over 90%, enabling the directional generation of aldehydes and / or alcohols.

[0006] To achieve the above objectives, the present invention provides a method for preparing a cobalt-based catalyst for olefin hydroformylation reaction, the method comprising: (1) Add a precipitant to the cobalt salt solution, perform hydrothermal treatment at 150℃~180℃, centrifuge, wash, dry, and calcine at 200℃~500℃ to obtain the Co3O4 precursor; (2) When the Co3O4 precursor is placed in a reducing gas stream at 200℃~300℃, a high-valence cobalt catalyst is obtained; Or / when the Co3O4 precursor is reduced in a reducing gas stream at 300℃~450℃, a low-valent cobalt catalyst is obtained; The high-valent cobalt catalyst contains Co. 2+ / Co 3+ Co-free 0 (or Co) 0 The content is below the detection limit and does not affect the catalytic performance; the low-valent cobalt catalyst contains Co. 0 Co-free 2+ / Co 3+ (or Co) 2+ / Co 3+ The content is below the detection limit and does not affect the catalytic performance.

[0007] The "Co3O4 precursor" of this invention is crucial for ensuring the dispersion of active species. Using unreduced Co3O4 precursor as a catalyst results in low conversion rates and no aldehyde or alcohol formation. The reduction step is a core prerequisite for activating the catalytic activity of Co3O4 and achieving directional selectivity. The unreduced Co3O4 precursor contains only spinel-structured Co. 2+ / Co 3+ Without active valence state regulation, it cannot activate H2 or CO, resulting in low conversion rates due to unactivated active sites; it lacks directional catalytic ability; and it produces high levels of byproducts (olefin isomerization products). A hydrogen concentration of 5%–100% is crucial for ensuring the reduction degree. The effect of hydrogen concentration on the performance of the prepared catalyst was investigated using a 2% H2 / 98% Ar method. The prepared catalyst, with Co as its active ingredient, was then used in the catalyst… 2+ / Co 3+ Mainly (small amount of Co) 0 Insufficient hydrogen concentration leads to incomplete reduction, Co 0 The amount produced is small, and its aldehyde selectivity is lower than that of hydrogen gas with a volume fraction of 5% to 100%.

[0008] Preferably, in step (1), the cobalt salt in the cobalt salt solution includes any one or more of cobalt nitrate, cobalt carbonate, cobalt chloride, cobalt sulfate, and cobalt acetate; the precipitant includes any one or more of hydroxide, carbonate, bicarbonate, and urea.

[0009] Preferably, the hydrothermal treatment time is 2h to 10h and the pH value is 7 to 10; the heating rate of the hydrothermal treatment at 150℃ to 180℃ is 20℃ / min to 10℃ / min.

[0010] Preferably, the calcination time is 2h to 10h and the heating rate is 2℃ / min to 10℃ / min.

[0011] Preferably, in step (2), the reducing gas flow contains 5% to 100% hydrogen by volume and 0% to 95% inert gas (such as nitrogen, argon or helium by volume); the flow rate of the reducing gas flow is 5 mL / min to 20 mL / min.

[0012] Preferably, in step (2), the reduction time is 1h to 3h and the heating rate is 2℃ / min to 10℃ / min.

[0013] The present invention provides a cobalt-based catalyst for olefin hydroformylation reaction prepared by the method described above.

[0014] This invention provides an application of a cobalt-based catalyst prepared as described in the method for the hydroformylation of olefins.

[0015] Preferably, the olefin is a medium- to long-chain α-olefin with a total of 5 or more carbon atoms, and the carbon chain contains an ester group, methyl-10-undecenoate.

[0016] More preferably, the medium-to-long chain α-olefin is an olefin with a carbon chain length of 5 to 15, a five- to eight-membered ring olefin, or an olefin containing an ester group.

[0017] More preferably, the olefin with a carbon chain length of 5 to 15 is selected from 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetracene, 1-tetradecene, or 1-pentadene.

[0018] Preferably, when generating the aldehyde with one more carbon atom in the medium-to-long-chain α-olefin, the catalyst used is a catalyst containing Co. 0 A low-cost cobalt catalyst; for the formation of the medium-to-long-chain α-olefin alcohol with one more carbon atom, the catalyst used is a Co-containing catalyst. 2+ / Co 3+ The high-valence cobalt catalyst, wherein the medium- and long-chain α-olefin in the alcohol with one more carbon is selected from olefins with a carbon chain length of 5 to 15, five- to eight-membered ring olefins, or olefins containing ester groups.

[0019] More preferably, the reaction conditions for the hydroformylation of the olefin are as follows: in a batch reactor, the synthesis gas volume ratio is CO:H2 = (1~3):1, the reaction pressure is 0.1 MPa~10.0 MPa, the reaction temperature is 40℃~200℃, and the reaction solvent is selected from any one or more of cyclohexane, toluene, 1,4-dioxane, tetrahydrofuran, and p-xylene.

[0020] More preferably, the catalyst used is one containing Co. 0 When using a low-cost cobalt catalyst, the reaction solvent is selected from any one of cyclohexane, toluene, 1,4-dioxane, tetrahydrofuran, and p-xylene, and the reaction temperature is ≤140℃; the catalyst used is a Co-containing catalyst. 2+ / Co 3+The high-valent cobalt catalyst is reacted in a polar ether solvent (tetrahydrofuran or 1,4-dioxane).

[0021] This invention discloses a cobalt-based catalyst for the hydroformylation of olefins, its preparation, and its application. This catalyst overcomes the limitations of existing technologies, which rely on complex ligands / bimetals, have limited control dimensions, require stringent conditions, and lack universality, making it difficult to simultaneously achieve high selectivity, high stability, and broad substrate compatibility. It offers the following advantages: 1. The Co3O4 precursor of this invention is prepared by a two-step precipitation-hydrothermal method. Specific technical details include: first, precipitation at room temperature (10~70℃, pH 7~10) to form a cobalt-based hydroxide / carbonate precursor, followed by a hydrothermal reaction at 150~180℃, rather than a single hydrothermal treatment; and the hydrothermal heating rate (10~20℃ / min) and holding time (2~10h) need to be controlled in conjunction with the precipitation pH. The principle is that the two-step operation of "dropwise addition of NaOH precipitation → hydrothermal reaction at 180℃ for 5h" avoids particle agglomeration caused by direct precipitation—room temperature precipitation with pH 7~10 ensures complete precipitation of cobalt ions without impurities, while the subsequent hydrothermal reaction promotes particle crystallization through high temperature and pressure, forming a Co3O4 precursor with uniform particle size, laying the foundation for the dispersion of active species during subsequent reduction.

[0022] 2. The catalyst of this invention exhibits high selectivity and controllability: By adjusting the catalyst reduction temperature, precise control of the valence state of cobalt active species is achieved—using Co... 2+ / Co 3+ Using a high-valent cobalt catalyst as the primary catalyst and a polar ether solvent (tetrahydrofuran or 1,4-dioxane) as the reaction solvent, the alcohol selectivity of the hydroformylation reaction of olefins can reach over 90%. 0 The use of a low-cost cobalt catalyst as the main component and a reaction temperature of ≤140℃ can achieve an aldehyde selectivity of over 90%, solving the problem of difficult selectivity control in existing technologies.

[0023] 3. The catalysts of this invention exhibit excellent stability: after four cycles of use, the activity and selectivity of both catalysts show no significant decline; they have broad substrate versatility: they can efficiently catalyze straight-chain olefins, internal olefins, cyclic olefins, and functional group-containing olefins; the preparation process is simple and low-cost: the catalysts use inexpensive cobalt salts as raw materials, requiring no complex ligand modification or noble metal doping, and the preparation process only requires hydrothermal treatment, calcination, and reduction, making the process easy to scale up; the reaction conditions are mild, lower than the reaction conditions of existing bimetallic catalysts or high-temperature controlled processes, resulting in low energy consumption and low equipment requirements, making them suitable for industrial applications. Attached Figure Description

[0024] Figure 1 The images show the XRD characterization of catalyst A in Example 1 and catalyst B in Example 2.

[0025] Figure 2The above are H2-TPR characterization diagrams of the precursor, catalyst A in Example 1, and catalyst B in Example 2. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that: if specific conditions are not explicitly marked in the examples, they should be performed according to conventional conditions or conditions recommended by the manufacturer; if the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be purchased on the market.

[0028] In this invention, all features defined in the form of numerical ranges or percentage ranges (e.g., numerical values, quantities, contents, and concentrations) are described only for the sake of brevity and convenience. Therefore, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and each numerical value (including integers and fractions) within that range.

[0029] The features mentioned in this invention can be combined arbitrarily, and all possible combinations should be considered as included within the scope of this specification, provided that there is no contradiction in the combination of such features. Each feature disclosed in this specification can be replaced by any alternative feature capable of achieving the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are merely general examples of equivalent or similar features.

[0030] In this invention, unless otherwise stated, the term "medium- and long-chain α-olefin" specifically refers to olefins with a total number of 5 or more carbon atoms, preferably olefins with a total number of carbon atoms in the range of 5 to 15.

[0031] Example 1 A method for preparing a cobalt-based catalyst for olefin hydroformylation reaction, the method comprising: (1) Preparation of Co3O4 precursor Weigh out 0.01 mol Co(NO3)2・6H2O and 0.01 mol CoCl2・6H2O respectively, add 30 mL of deionized water, and stir magnetically for 30 min until completely dissolved; then slowly add 10 mL of 1 mol / L NaOH solution and continue stirring for 1 h; transfer the mixture to a 50 mL polytetrafluoroethylene-lined reactor and keep it at 180℃ for 5 h; after cooling to room temperature, centrifuge at 8000 rpm for 10 min to collect the precipitate, wash it 4 times alternately with ethanol and deionized water, and dry it under vacuum at 60℃ for 10 h; finally, place the dried product in a muffle furnace and calcine it at 400℃ for 3 h to obtain black Co3O4 precursor powder.

[0032] (2) Take 2.0 g of Co3O4 precursor powder and place it in a reduction furnace. Introduce H2 gas flow (flow rate 50 mL / min) and heat to 250℃ at 5℃ / min. Hold at 250℃ for 3 h. After cooling to room temperature, switch to N2 protection (after the reduction reaction is completed, maintain the reducing gas flow (such as H2), stop heating, and let the reactor cool naturally with the furnace (cooling rate is about 5℃ / min~8℃ / min, no additional rate control is required) until the temperature of the outer wall of the reactor is consistent with room temperature (25±2℃), then turn off the reducing gas). Collect catalyst A (high-valent cobalt catalyst, containing Co). 2+ / Co 3+ ).

[0033] Example 2 The preparation method of a cobalt-based catalyst for olefin hydroformylation is basically the same as that in Example 1, except that: In step (2), the heating rate of 5℃ / min to 250℃ and holding at 250℃ for 3 hours was adjusted to 5℃ / min to 350℃ and holding at 350℃ for 1 hour; catalyst B (low-valent cobalt catalyst, containing Co) was obtained through the same operation as in Example 1. 0 ).

[0034] like Figure 1 The image shows the XRD characterization patterns of catalyst A in Example 1 and catalyst B in Example 2, where A is the catalyst prepared in Example 1 and B is the catalyst prepared in Example 2. Figure 1 It can be seen that for catalyst A (reduction at 250℃, high-valent cobalt catalyst): obvious Co3O4 characteristic peaks appear in the diffraction pattern (corresponding to JCPDS standard card No. 01-078-1969), with peak positions of 31.3° (220), 36.8° (311), 44.8° (400), 59.4° (511), and 65.3° (440), respectively, with no Co. 0 Characteristic peak (Co) 0The standard peak positions are 44.2°, 51.5°, and 75.9° (corresponding to JCPDS No. 01-071-4617). This demonstrates that the cobalt species in catalyst A is primarily Co. 2+ / Co 3+ The dominant peak is Co3O4 (incompletely reduced), and the characteristic peaks are sharp and free of impurities, indicating that the Co3O4 crystal structure is intact and well-dispersed. For catalyst B (reduced at 350℃, low-valent cobalt catalyst): the characteristic peaks of Co3O4 completely disappear in the diffraction pattern, replaced by Co. 0 The three strong characteristic peaks are 44.2° (111), 51.5° (200), and 75.9° (220), with sharp peak shapes and high intensity, proving that Co3O4 has been completely reduced to metallic Co. 0 Therefore, reduction temperature is the core factor controlling the crystal phase of cobalt species—reduction at 200℃~300℃ can only partially reduce Co3O4 (preserving the Co3O4 crystal phase, i.e., Co). 2+ / Co 3+ ), can be completely converted to Co by reduction at 300℃~450℃. 0 The crystal phase is consistent with the core technology of "valence state regulation" in this invention.

[0035] like Figure 2 The image shows the H2-TPR characterization diagrams of the precursor, catalyst A in Example 1, and catalyst B in Example 2. (Source: [Insert source here]) Figure 2 It can be seen that for the Co3O4 precursor, two consecutive reduction peaks appear: the first peak is located at 250℃~320℃ (main peak at 280℃), corresponding to Co in Co3O4. 3+ →Co 2+ The reduction reaction (reaction formula: Co3O4 + H2 → 3CoO + H2O); the second peak is located at 350℃~450℃ (main peak at 400℃), corresponding to the Co in CoO. 2+ →Co 0 The reduction reaction (reaction formula: CoO + H2 → Co + H2O) proves that the precursor is pure Co3O4. For catalyst A (reduction at 250℃): only a weak hydrogen-consuming peak appears in the 250~320℃ range (the peak area is only 10% of the first peak of the precursor), and hydrogen-consuming peaks also appear in the 350~450℃ range. This indicates that the reduction at 250℃ can only reduce a portion of Co. 3+ →Co 2+ (Co not triggered) 2+ →Co 0 Furthermore, the reduction reaction is nearly complete (with very little remaining hydrogen consumption), and the final product is Co. 2+ / Co 3+Mixed valence state (i.e., high-valence cobalt catalyst), consistent with XRD analysis. For catalyst B (reduction at 350℃): no hydrogen consumption peak in the 250~320℃ range (Co). 3+ Completely → Co 2+ Only one strong hydrogen-consuming peak appears in the 350–450 °C range (peak area is 95% of the second peak of the precursor), and the peak position is slightly shifted towards the lower temperature (380 °C). This indicates that reduction at 350 °C can reduce Co... 2+ High efficiency → Co 0 The reduction reaction was almost complete, and the final product was pure Co. 0 (i.e., low-cost cobalt catalyst), and XRD analysis and catalytic performance data ( Figure 1 (Complete match)

[0036] Comparative Example 1 The preparation method of a cobalt-based catalyst is basically the same as that in Example 1, except that: No step (1); In step (2), 2.0g of Co3O4 precursor powder was adjusted to 2.0g of CoO powder, and the heating rate was adjusted from 5℃ / min to 250℃ and held at 250℃ for 3h to 5℃ / min to 350℃ and held at 350℃ for 3h. Catalyst 1 was obtained by the same operation as in Example 1.

[0037] Comparative Example 2 The preparation method of a cobalt-based catalyst is basically the same as that in Example 1, except that: Step (2) is omitted; 50 mg of Co3O4 precursor is directly used as catalyst 2.

[0038] Comparative Example 3 To investigate the effect of hydrogen concentration on the performance of the prepared catalyst, the preparation method was basically the same as in Example 1, with the following differences: In step (2), the H2 gas flow is adjusted to 2% H2 / 98% Ar, the flow rate remains unchanged, and catalyst 3 is obtained by the same operation as in Example 1.

[0039] Example 3 The preparation method of a cobalt-based catalyst for olefin hydroformylation is basically the same as that in Example 1, except that: In step (2), the temperature holding time of 250°C for 3 hours was adjusted to 250°C for 1 hour; the C catalyst was obtained by the same operation as in Example 1.

[0040] Example 4 The preparation method of a cobalt-based catalyst for olefin hydroformylation is basically the same as that in Example 1, except that: In step (2), the heating rate of 5℃ / min to 250℃ and holding at 250℃ for 3h was adjusted to 5℃ / min to 300℃ and holding at 300℃ for 1h; the D catalyst was obtained through the same operation as in Example 1.

[0041] Example 5 The preparation method of a cobalt-based catalyst for olefin hydroformylation is basically the same as that in Example 1, except that: In step (2), the heating rate of 5℃ / min to 250℃ and holding at 250℃ for 3h was adjusted to heating rate of 5℃ / min to 300℃ and holding at 300℃ for 2h; catalyst E was obtained through the same operation as in Example 1.

[0042] Example 6 The preparation method of a cobalt-based catalyst for olefin hydroformylation is basically the same as that in Example 1, except that: In step (2), 600 mg of Co3O4 precursor powder was placed in a fixed-bed quartz tube reactor and a gas flow of 10% H2 / 90% Ar (volume ratio) was introduced (total flow rate 15 mL / min); the F catalyst (high-valence cobalt catalyst) was obtained by the same operation as in Example 1.

[0043] Experimental Example 1: Verifying the Catalytic Performance of the Catalyst Catalysts A to E prepared in Examples 1 to 6 and Comparative Examples 1 to 3 of this invention were applied to the hydroformylation reaction of medium- and long-chain α-olefins under corresponding hydroformylation reaction conditions. The purpose of this application is to examine the catalytic performance of different catalysts and different reaction conditions in the hydroformylation reaction of medium- and long-chain α-olefins to generate higher alcohols and higher aldehydes through the valence state regulation of active species.

[0044] (1) Effect of different catalysts on the catalytic performance of hydroformylation products 0.5 mmol of 1-octene, 50.0 mg of catalyst (catalysts A-E prepared in Examples 1-6 of this invention), and 3.0 mL of THF were added to a 100 mL batch reactor. After sealing the reactor, it was purged three times with 1 MPa syngas (H2 / CO = 1:1) to a pressure of 4 MPa. The temperature was raised to 140 °C, and the reaction was stirred for 12 h. After the reaction was completed, the reactor was cooled to room temperature (after the hydroformylation reaction was completed, the heating device was turned off, and the reactor was allowed to cool naturally at room temperature. After the temperature inside the reactor dropped to room temperature, the remaining pressure inside the reactor was slowly released at a rate ≤0.5 MPa / min to prevent product splashing before opening the reactor lid to take a sample). Biphenyl was added to the sample as an internal standard. The reaction solution was analyzed by gas chromatography using an HP-7890N equipped with an HP-5 capillary column and an FID detector. The results are shown in Table 1.

[0045] Table 1. Product selectivity of the catalyst in the hydroformylation reaction in the examples. As shown in Table 1, Examples 1-6 of this invention used Co3O4 as a precursor and, by controlling the H2 reduction temperature, prepared high-valent cobalt species (Co... 2+ / Co 3+ Catalysts primarily composed of cobalt (catalyst A and catalyst C) and those primarily composed of low-cost cobalt species (Co) 0 Catalysts (Catalyst B, Catalyst D, and Catalyst E) were used for the hydroformylation of olefins. Under syngas conditions of 140℃, 4MPa, and H2 / CO = 1:1, Catalyst A catalyzed the reaction for 12 hours to induce the directed formation of alcohols (1-octene conversion > 99%, alcohol selectivity 91%), while Catalyst B catalyzed the reaction for 12 hours to induce the directed formation of aldehydes (1-octene conversion > 99%, aldehyde selectivity 90%). Comparative Example 1 directly used the reduction of CoO (a non-Co3O4 precursor), and the resulting catalyst 1 contained only Co. 0 The conversion rate was 90%, the selectivity for aldehydes was 78%, and the selectivity for alcohols was 5%. This was because the absence of the Co3O4 precursor led to the Co... 0 Poor dispersibility; aldehyde selectivity was lower than that of Example 2B (93%), proving that the "Co3O4 precursor" is key to ensuring the dispersibility of active species. Comparative Example 2 used unreduced Co3O4 precursor as catalyst, with a conversion rate of 8% and 100% selectivity for byproducts, with no aldehyde or alcohol formation; the unreduced Co3O4 precursor contained only spinel-structured Co. 2+ / Co 3+ Without active valence state regulation, it cannot activate H2 or CO, resulting in low conversion rates due to unactivated active sites; it lacks directional catalytic ability; and it produces a high amount of byproducts (olefin isomerization products). This demonstrates that the reduction step in Example 2 of this invention is a core prerequisite for activating the catalytic activity of Co3O4 and achieving directional selectivity, further highlighting the necessity of the reduction step in Example 2. Comparative Example 3 investigated the effect of hydrogen concentration on the performance of the prepared catalyst using 2% H2 / 98% Ar. The prepared catalyst was prepared with Co... 2+ / Co 3+ Mainly (small amount of Co) 0 The conversion rate was 92%, the selectivity for aldehydes was 30%, and the selectivity for alcohols was 64%. Insufficient hydrogen concentration led to incomplete reduction. (Co) 0 The low amount of aldehyde produced and the lower selectivity of aldehyde compared to catalyst B (93%) in Example 2 of this invention demonstrate that a hydrogen concentration of 5% to 100% is crucial to ensuring the degree of reduction.

[0046] (2) Effect of different temperatures on the catalytic performance of hydroformylation to aldehyde / alcohol formation The method of hydroformylation of catalysts A and B at different temperatures is the same as the method of (1) above for the effect of different catalysts on the catalytic performance of hydroformylation products. The results are detailed in Table 2.

[0047] Table 2. Effects of catalysts A and B on the selectivity of hydroformyl alcohols at different temperatures. As shown in Table 2, the catalyst provided by this invention controls the hydroformylation of long-chain α-olefins to generate higher alcohols and aldehydes by varying the valence state of the active metal at different reduction temperatures. For catalyst A (Co... 2+ / Co 3+ (Mainly): At 120℃, the temperature is relatively low, and H2 in Co 2+ / Co 3+ The activation rate at acidic sites is slow (high energy barrier for HH bond breaking), resulting in incomplete hydrogenation of the aldehyde → alcohol. Therefore, the alcohol selectivity is only 72%, and the aldehyde selectivity remains at 36%. At 140℃: the temperature rises to the optimal range for H2 activation (energy barrier drops to its lowest level), the hydrogenation rate increases significantly, the aldehyde is almost completely converted to an alcohol, the alcohol selectivity rises to 91%, and the aldehyde selectivity drops to 6%. At 160℃: the excessively high temperature does not lead to a decrease in selectivity (alcohol selectivity 93%), because Co... 2+ / Co 3+ The Lewis acidity remained stable at 160℃, and the high temperature accelerated the mass transfer rate, maintaining a conversion rate of 99%, proving that catalyst A (high-valent cobalt catalyst) has a wide applicable temperature range (140~160℃). For catalyst B (Co... 0 (Mainly): At 120℃: the temperature is relatively low, CO and Co... 0 The coordination activation rate of Co is slow, but Co 0 There is no hydrogenation activity, therefore the aldehyde selectivity remains as high as 94% (only a small amount of aldehyde remains due to incomplete reaction), and the conversion rate is 99% (olefin adsorption is not affected by low temperature); at 140℃: the temperature rises to the optimal range for CO activation, the CO insertion rate accelerates, the aldehyde selectivity remains at 93%, and the conversion rate is 99%; at 160℃: the temperature is too high, leading to Co... 0 Slight particle aggregation reduced the number of active sites, and high temperature promoted the olefin isomerization side reaction, so the aldehyde selectivity dropped to 80%, while the alcohol selectivity increased slightly (15%) due to the side reaction. This proves that the temperature of catalyst B (low-valent cobalt catalyst) needs to be controlled at ≤140℃ to avoid aggregation.

[0048] (3) Effect of different solvents on the catalytic performance of hydroformylation to aldehyde / alcohol The method of hydroformylation of catalysts A and B in different solvents is the same as the method of (1) above for the effect of different catalysts on the catalytic performance of hydroformylation products. The results are detailed in Table 3.

[0049] Table 3. Effects of catalysts A and B on the selectivity of hydroformyl alcohols in different solvents. As shown in Table 3, the catalyst A (high-valent cobalt catalyst, Co) provided by this invention 2+ / Co 3+ Mainly): THF / 1,4-dioxane (polar ether solvent): The oxygen atom in the solvent molecule can react with Co. 2+ / Co 3+ The formation of weak coordination bonds (electron transfer from O to Co) stabilizes Co. 2+ / Co 3+ The Lewis acidic sites (preventing acidic sites from being occupied by reaction impurities) do not hinder the adsorption of H2 and aldehyde intermediates, thus achieving an alcohol selectivity of up to 91% / 90% and an aldehyde selectivity of only 6% / 7%; Toluene (a non-polar solvent): lacks strong coordinating atoms (such as O, N), and cannot stabilize Co. 2+ / Co 3+ The acidic sites of catalyst A are easily occupied by olefin molecules, leading to a decrease in H2 activation efficiency and hindering the aldehyde-to-alcohol hydrogenation reaction. Therefore, the alcohol selectivity drops sharply to 12%, while the aldehyde selectivity rises to 83%, proving that polar ether solvents are a necessary condition for catalyst A to achieve high alcohol selectivity. For catalyst B (Co... 0 (Mainly): Toluene / THF / 1,4-dioxane: Regardless of solvent polarity, aldehyde selectivity remains at 89%~93%, while alcohol selectivity is only 5%~7%. The reason is Co... 0 Co has a high d-orbital electron density, requires no solvent stability (no acidic sites), and solvent molecules (regardless of polarity) cannot compete with it. 0 Active sites (CO and Co) 0 The coordination ability of catalyst B is much stronger than that of solvent, so the CO insertion reaction is not affected by solvent and the aldehyde selectivity is stable, proving that catalyst B has a wider range of solvent adaptability.

[0050] Experimental Example 2: Verifying the stability of the catalyst Taking catalyst A and catalyst B prepared in Examples 1 and 2 as examples, the reusability of the two catalysts in the catalytic hydroformylation reaction of 1-octene was investigated. The specific operation method was the same as that in Experiment 1 (1) regarding the effect of different catalysts on the catalytic performance of the hydroformylation reaction product. The reaction data of catalyst reuse are shown in Tables 4 and 5.

[0051] Table 4. Reusability of catalyst A in Example 1 Table 5. Reusability of catalyst B in Example 2 As can be seen from Tables 4 and 5, the two catalysts prepared in this invention can be reused at least four times while maintaining a high level of catalytic activity.

[0052] Experimental Example 3: Verifying the substrate adaptability of the catalyst Taking catalyst A and catalyst B prepared in Examples 1 and 2 as examples, the general performance of the two catalysts in catalyzing the hydroformylation reaction of different olefins was investigated. The specific operation method was basically the same as that in Experiment 1 (1) regarding the effect of different catalysts on the catalytic performance of the hydroformylation reaction product. The difference was that 0.5 mmol of different olefin substrates were used instead of 0.5 mmol of 1-octene. The specific structure and reaction results are shown in Tables 5 and 6 below.

[0053] Table 6 Catalytic performance of catalyst A in different olefin hydroformylation reactions to alcohols Note: In the table, l / b represents the positive-to-negative ratio of the generated aldehydes, and the same applies to the following tables.

[0054] Table 7 Catalytic performance of catalyst A in the hydroformylation of olefins to aldehydes As can be seen from Tables 5 and 6, the catalytic materials prepared in this invention exhibit excellent catalytic activity and good applicability when applied to the hydroformylation reactions of different aliphatic olefins.

[0055] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for preparing a cobalt-based catalyst for the hydroformylation reaction of olefins, characterized in that, The method includes: (1) Add a precipitant to the cobalt salt solution, perform hydrothermal treatment at 150℃~180℃, centrifuge, wash, dry, and calcine at 200℃~500℃ to obtain the Co3O4 precursor; (2) When the Co3O4 precursor is placed in a reducing gas stream at 200℃~300℃, a high-valence cobalt catalyst is obtained; Or / when the Co3O4 precursor is reduced in a reducing gas stream at 300℃~450℃, a low-valent cobalt catalyst is obtained; The high-valent cobalt catalyst contains Co. 2+ / Co 3+ ; The low-cost cobalt catalyst contains Co. 0 .

2. The method according to claim 1, characterized in that, In step (1), the cobalt salt in the cobalt salt solution includes any one or more of cobalt nitrate, cobalt carbonate, cobalt chloride, cobalt sulfate, and cobalt acetate; the precipitant includes any one or more of hydroxide, carbonate, bicarbonate, and urea.

3. The method according to claim 2, characterized in that, The hydrothermal treatment time is 2h~10h, and the pH value is 7~10; the heating rate of the hydrothermal treatment at 150℃~180℃ is 20℃ / min~10℃ / min.

4. The method according to claim 2, characterized in that, The calcination time is 2h to 10h, and the heating rate is 2℃ / min to 10℃ / min.

5. The method according to claim 1, characterized in that, In step (2), the reducing gas stream contains 5% to 100% hydrogen and 0% to 95% inert gas by volume.

6. The method according to claim 1, characterized in that, In step (2), the reduction time is 1h to 3h and the heating rate is 2℃ / min to 10℃ / min.

7. A cobalt-based catalyst for olefin hydroformylation prepared by the method according to any one of claims 1 to 6.

8. The application of a cobalt-based catalyst for the hydroformylation of olefins prepared by the method according to any one of claims 1 to 6 in the hydroformylation of olefins.

9. The application according to claim 8, characterized in that, The hydroformylation reaction produces an aldehyde with one more carbon atom in the medium-to-long chain α-olefin and / or an alcohol with one more carbon atom in the medium-to-long chain α-olefin.

10. The application according to claim 9, characterized in that, When generating the aldehyde with one more carbon atom in the medium-to-long-chain α-olefin, the catalyst used is a catalyst containing Co. 0 A low-cost cobalt catalyst; for the formation of the medium-to-long-chain α-olefin alcohol with one more carbon atom, the catalyst used is a Co-containing catalyst. 2+ / Co 3+ The high-valence cobalt catalyst, wherein the medium- and long-chain α-olefin in the alcohol with one more carbon is selected from olefins with a carbon chain length of 5 to 15, five- to eight-membered ring olefins, or olefins containing ester groups.

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