A cobalt-based hydroformylation pre-catalyst

Abstract

The present application relates to a kind of ligand-free cobalt-based hydroformylation pre-catalyst and its preparation method and application, belong to fine chemical catalytic material and catalytic reaction technical field.The pre-catalyst is prepared by solvothermal method: the mixture of cobalt precursor and amino-containing compound in solvent is separated by solid-liquid after solvothermal reaction, drying, and calcination at 200~450 °C;Raw material is only composed of cobalt salt, amino-containing compound and optional carrier / solvent, does not contain organic ligand and noble metal.The pre-catalyst can generate cobalt carbonyl active species (infrared 2000~2250 cm ‑1 Characteristic peak) in situ under ≥100 °C, ≥2 MPa in synthesis gas (CO / H2).For olefin hydroformylation, 1-octene conversion is ≥99%, aldehyde selectivity is ≥75%, normal-isomer ratio is about 1.7, significantly better than direct use of cobalt salt (normal-isomer ratio is about 0.5, mainly branched aldehyde).After reaction, product is separated by vacuum distillation at <60 °C, and cobalt-containing residue can be recycled.The solid pre-catalyst prepared by solvothermal method in the present application realizes low-cost, ligand-free, high-linear-selectivity hydroformylation, and has good industrialization prospect.

Description

Technical Field

[0001] This invention relates to a ligand-free cobalt-based hydroformylation precatalyst, its preparation method, and its application, belonging to the field of fine chemical catalytic materials and catalytic reaction technology. Background Technology

[0002] The hydroformylation of olefins is a reaction in which olefins are converted into aldehydes under the action of CO and H2. It is one of the largest homogeneous catalytic processes in industrial scale, with a global annual production capacity of over 10 million tons. The aldehydes and their derivatives are widely used in the manufacture of fine chemicals and bulk chemicals such as alcohols, acids, and esters.

[0003] The catalyst system for hydroformylation has evolved from cobalt to rhodium. Cobalt-based homogeneous catalysts were the earliest industrialized system, with Co₂(CO)₈ as the active species or HCo(CO)₄ generated from its reaction with H₂. However, the carbonyl cobalt species has poor thermal stability and is easily decomposed and deactivated at elevated temperatures. It must be kept stable in the reaction medium under relatively high pressures (20–30 MPa). Furthermore, the preparation of Co₂(CO)₈ itself requires carbonylation of cobalt salts under high-pressure CO conditions, which are demanding. After the reaction, the carbonyl cobalt species coexists with the product aldehyde in the liquid phase, making separation and recovery difficult. Typically, cobalt is recovered by oxidation or acid washing to precipitate it, a complex process with significant cobalt loss.

[0004] To reduce reaction pressure and improve selectivity, cobalt-based homogeneous catalysts modified with phosphine ligands have been proposed. The introduction of ligands improves the thermal stability of cobalt carbonyl species, allowing the reaction to proceed at lower pressures (5–10 MPa), and also enhances the selectivity for n-aldehydes. However, ligand-modified systems also face significant challenges: phosphine ligands are prone to oxidative degradation or C-P bond breakage under reaction conditions, leading to gradual catalyst deactivation; the ratio of ligand to cobalt needs precise control, as excess ligand significantly reduces reaction activity; ligands are costly and difficult to separate and recover from the product; furthermore, cobalt species still exist in a homogeneous form in the reaction solution, making recycling difficult.

[0005] To achieve catalyst separation and recycling, heterogeneous strategies have been extensively studied. In cobalt-based heterogeneous catalysis, Co3O4 and its supported systems are the main research directions. Studies have shown that Au / Co3O4 can catalyze the hydroformylation of 1-hexene under mild conditions with an aldehyde selectivity exceeding 85% (X. Liu, Appl. Catal. B-Environ., 2009, 92(3-4): 206–214), but it depends on the noble metal Au as a promoter; morphology-controlled Co3O4 octahedral nanocrystals can catalyze the hydroformylation of 1-heptene, but the cubic structure with exposed {100} faces only undergoes isomerization (JE Lee, Fuel, 2020, 269: 117397); fibrous Co3O4 can achieve the reductive hydroformylation of 1-octene, but the product is mainly an alcohol rather than an aldehyde (SS Bhagade, Catal. Today, 2017, 309:147–152). Overall, multiphase cobalt-based systems suffer from problems such as low activity, poor aldehyde selectivity, and susceptibility to isomerization or excessive hydrogenation, and there are no successful industrial applications to date (C.-A. Liang, Chin. J. Catal., 2025, 70:115-141).

[0006] This reveals a core contradiction in existing technologies: homogeneous cobalt catalysts exhibit high activity and good aldehyde selectivity, but their preparation conditions are demanding, their stability is poor, and their recycling is difficult; heterogeneous cobalt catalysts are easy to separate, but their activity and selectivity are insufficient. Therefore, there is an urgent need for a novel cobalt-based catalytic system that requires no ligands or precious metals, can be activated in situ under reaction conditions to form active species, and allows for the concentration and recycling of the reaction residue.

[0007] To overcome the shortcomings of existing technologies, this invention provides a novel cobalt-based hydroformylation precatalyst and its preparation method. This precatalyst is prepared through a special synthesis process, requiring no precious metal assistance, and generates catalytically active carbonyl-like cobalt species in situ under reaction conditions. Compared with existing technologies, this invention has the following advantages: (1) the preparation process is simple, requiring no precious metal assistance, and is low in cost; (2) no organic ligands are required, avoiding the problems of high ligand cost, poor stability, and cumbersome operation; (3) the active species are generated in situ under reaction conditions, making operation simple; (4) the catalyst can be recycled through vacuum distillation, exhibiting excellent cycle stability; (5) it can be directly applied to olefin hydroformylation reactions, showing promising industrial application prospects. This invention provides a novel technical route for developing high-performance, low-cost, and easily recyclable cobalt-based hydroformylation catalysts. Summary of the Invention

[0008] The present invention aims to overcome the technical defects of existing cobalt-based hydroformylation catalysts, which require expensive and sensitive phosphine ligands or noble metals to regulate selectivity, while the direct use of low-cost cobalt salts (such as cobalt acetate) results in poor regioselectivity and low yield of straight-chain aldehydes.

[0009] To address the aforementioned problems, this invention provides a ligand-free cobalt-based hydroformylation precatalyst. Through extensive research, this invention proposes a novel inventive concept: utilizing an amino-containing compound (preferably urea) as a structure-directing agent, a solid precatalyst with a specific phase (Co3O4 or an unknown cobalt compound) is prepared by reacting it with cobalt salts via solvothermal processes. This precatalyst can generate active cobalt species in situ under hydroformylation reaction conditions; unexpectedly, its unique phase and surface structure can produce a "ligand-like" regulatory effect, reversing the regioselectivity from predominantly branched aldehydes (positive-to-isotropic ratio ~0.5) under conventional cobalt salt catalysis to predominantly straight-chain aldehydes (positive-to-isotropic ratio >1.5). To achieve this inventive concept, this invention adopts the following technical solution: The precatalyst is prepared by a method including the following steps: mixing a cobalt precursor with an amino-containing compound in a solvent and carrying out a solvothermal reaction; the resulting product is separated into solid and liquid phases, dried, and then calcined at 200-450 °C under an inert atmosphere or an air atmosphere to obtain the precatalyst. The raw materials used in the preparation method consist only of cobalt precursor, amino-containing compound and solvent, without any added organic ligands or precious metal elements.

[0010] The precatalyst has the following phase characteristics: The precatalyst is at 60~120°C. o The phase after drying (C) is one or more of the following: (a), (b), (c), and (d): (a) Co3O4, whose X-ray diffraction pattern shows characteristic diffraction peaks of Co3O4; (b) CoO, whose X-ray diffraction pattern shows characteristic diffraction peaks of CoO; (c) A cobalt compound having characteristic diffraction peaks in its X-ray diffraction pattern at 2θ angles of 14.6 °±0.2 °, 17.3 °±0.2 °, 23.9 °±0.2 °, 29.3 °±0.2 °, 30.9 °±0.2 °, 34.6 °±0.2 °, 35.2 °±0.2 °, 36.3 °±0.2 °, 38.1 °±0.2 ° and 41.8 °±0.2 °; (d) CoCO3, whose X-ray diffraction pattern shows characteristic diffraction peaks of CoCO3.

[0011] The activation characteristics of the precatalyst are as follows: Under a syngas (CO / H2) atmosphere, treatment at ≥100 °C and ≥2 MPa pressure can generate cobalt carbonyl species, whose infrared spectra are in the range of 2000–2143 cm⁻¹. -1 and 2143~2250 cm -1 The presence of two sets of CO adsorption characteristic peaks in the region indicates that various catalytically active Co-CO structures were formed in situ.

[0012] The preparation method of the precatalyst includes the following steps: (a) Mixing the cobalt precursor with an amino-containing compound in a solvent; (b) The mixture from step (a) is subjected to a solvothermal reaction at 100-200 °C for 6-72 hours; (c) Separate the product from step (b) into solid and liquid phases, collect the solid, wash it, and dry it at 60-120 °C; (d) The product dried in step (c) is calcined at 200-450 °C for 2-6 hours under an inert atmosphere or an air atmosphere.

[0013] The raw material selection for the precatalyst: The cobalt precursor is selected from one or more of cobalt nitrate, cobalt acetate, cobalt carbonate, cobalt chloride, and cobalt oxalate. Preferably, the cobalt precursor is selected from cobalt nitrate, cobalt acetate, cobalt chloride, and cobalt oxalate. When cobalt carbonate is used as the precursor, the phase evolution of the resulting precatalyst is different from that of the above precursors (see Example 5 and discussion for details).

[0014] The amino-containing compound is selected from one or more of urea, ammonia, ethylenediamine, triethylamine, and ammonium acetate.

[0015] The molar ratio of the cobalt precursor to the amino-containing compound is 1:0.5 to 1:3.

[0016] When liquid phase processing is used, the solvent is selected from one or more of water, methanol, ethanol, isopropanol, and propylene glycol.

[0017] Optionally, a solid carrier, such as activated carbon, molecular sieve, or metal oxide, can be added to further improve the dispersibility of cobalt species and facilitate the rapid formation of active substances.

[0018] The above-mentioned precatalyst was used to catalyze the hydroformylation reaction of olefins with syngas. The olefins were selected from one or more of 1-octene, 2-octene, and diisobutylene.

[0019] The pre-catalyst hydroformylation reaction method includes: The pre-catalyst, olefin substrate, CO, and H2 are added to a reactor, and the reaction is carried out at a temperature of 120–180 °C, a pressure of 2–6 MPa, and an H2 / CO molar ratio of 0.5–2. During the reaction, the pre-catalyst is converted in situ into an active cobalt species, catalyzing the conversion of the olefin into the corresponding aldehyde product.

[0020] After the reaction is complete, the product is separated by vacuum distillation at <60 °C. The cobalt-containing residue obtained can be directly recycled for the next reaction.

[0021] The beneficial effects of this invention are as follows: The precatalyst exhibits a well-defined structure and good stability: prepared via a solvothermal method, the precatalyst is a single phase or mixture of Co3O4, CoO, or an unknown cobalt compound (with clearly defined XRD characteristic peaks). This precatalyst is a solid powder and can be stably stored at room temperature in air for extended periods (at least several months), avoiding the problems of easy decomposition and the need for low-temperature storage associated with traditional Co2(CO)8, and also outperforming the air sensitivity of phosphine ligand-modified cobalt catalysts.

[0022] The preparation method is simple, the conditions are mild, and the cost is low: This invention uses a two-step method of "solvent thermal reaction + calcination" to prepare the precatalyst. No oxygen-free operation is required, and the calcination atmosphere can be either an inert gas or air. The equipment requirements are low, and it is easy to scale up production. The raw materials consist only of cobalt precursor, amino-containing compound, and optional solvent and solid support. There are no added organic ligands (such as phosphine ligands, amine ligands, etc.) and no precious metal elements (such as Au, Pt, Pd, etc.), which significantly reduces the cost of raw materials.

[0023] In-situ generation of active cobalt species with excellent catalytic performance: The pre-catalyst of this invention can rapidly generate active species after treatment in a syngas (CO / H2) atmosphere at ≥120 °C and ≥2 MPa pressure, with its infrared spectrum in the range of 2000 ~ 2143 cm⁻¹. -1 and 2143 ~ 2250 cm -1 The presence of two sets of CO adsorption characteristic peaks in the region indicates the in-situ formation of catalytically active Co-CO structural species. In the hydroformylation reaction of olefins (1-octene, 160 °C, 4 MPa, 2 h), the precatalyst of this invention exhibits excellent activity, aldehyde selectivity, and n-aldehyde selectivity (see Example 1 for details).

[0024] The product separation is simple and the catalytic system is recyclable: After the reaction is completed, the product can be separated by vacuum distillation at <60 °C. The cobalt-containing residue obtained after distillation can be directly recycled for the next reaction, realizing the effective recovery and utilization of cobalt species and further reducing the cost of catalyst.

[0025] The substrate applicability is broad: the precatalyst of the present invention is not only highly efficient for straight-chain α-olefins (1-octene), but also exhibits good hydroformylation activity for branched-chain olefins (diisobutylene) and internal olefins (2-octene) (see Example 2 for details).

[0026] Effectively solves the core defects of existing technologies:

[0027] An unknown cobalt compound phase was discovered: During the solvothermal preparation process, this invention discovered a cobalt compound not previously documented in the literature, with clearly defined XRD characteristic peaks (14.6 °, 17.3 °, 23.9 °, 29.3 °, 30.9 °, 34.6 °, 35.2 °, 36.3 °, 38.1 °, 41.8 °). This compound exhibits hydroformylation catalytic activity after heat treatment. This discovery provides new possibilities for the phase design of cobalt-based catalysts.

[0028] The solvothermal method has irreplaceable advantages: compared with other preparation methods (reflux method, deposition precipitation method, grinding method), the precatalyst prepared by the solvothermal method exhibits the best performance in terms of activity, selectivity, and reproducibility. Experiments show that the solvothermal method can generate high pressure in a closed system, promoting the full reaction of cobalt precursors with amino-containing compounds to form highly dispersed Co3O4 or unknown cobalt compounds with specific crystal planes, which is difficult to achieve with other atmospheric pressure or solid-phase methods. Therefore, the solvothermal method constitutes the best embodiment of the present invention, possessing outstanding substantive features and significant progress. Attached Figure Description

[0029] Figure 1 The XRD curves of some of the precatalysts prepared in Examples 1, 5, and 6 of this invention under different temperature treatments are shown.

[0030] Figure 2 This is the in-situ infrared absorption spectrum of S1 in Embodiment 1 of the present invention.

[0031] Figure 3 This is a color comparison of the reaction solution after S1 (left) reacts with commercial Co3O4 (right) in Example 1 of the present invention. Detailed Implementation

[0032] The following describes implementation methods of several preferred embodiments of the present invention.

[0033] Example 1 (1) Experimental methods Preparation: Dissolve 1.0 g Co(NO3)2·6H2O and 0.5 g urea in 50 mL of deionized water, transfer to a 100 mL hydrothermal reactor, and react at 100 °C for 12 h. After cooling, centrifuge, wash three times each with water and ethanol, and dry at 120 °C for 4 h. Then, heat to 250 °C under N2 atmosphere, hold at that temperature for 4 h, and allow to cool naturally to obtain a black powder, denoted as S1.

[0034] Characterization: XRD showed cubic phase Co3O4 and unknown species (characteristic diffraction peaks at 2θ angles of 14.6°, 17.3°, 23.9°, 29.3°, 30.9°, 34.6°, 35.2°, 36.3°, 38.1° and 41.8°).

[0035] Catalytic reaction: In a 100 mL autoclave, 10 mg of the above precatalyst, 20 mL of toluene, 126 μL of 1-octene, and 20 μL of dodecane (internal standard) were added. The autoclave was purged with syngas (H2 / CO=1:1) and pressurized to 4 MPa. The temperature was raised to 160 °C, and the reaction was stirred for 2 h. The results are shown in Table 1. Cyclic reaction: After the reaction, solid and liquid were separated, and the filtrate was rotary evaporated to dryness at 50 °C to obtain a dark yellow solid. The solid was redissolved in toluene, and a second reaction was carried out under the same conditions (without adding fresh pre-catalyst). After the reaction was completed, it was again rotary evaporated to dryness at 50 °C, redissolved in toluene, and a third reaction was carried out under the same conditions. The above operation was repeated 4 times, and the conversion rate of 1-octene was still >95%, proving that the cobalt-containing residue could be reused. The results are shown in Table 2.

[0036] (2) Comparative Example 1: Blank reaction, without external catalyst, under the same reaction conditions, the results are shown in Table 1; (2) Comparative Examples 2-6: Commercial Co3O4, CoO, Co2O3, Co2(CO)8, and Co(OAc)2·4H2O were used instead of the above precatalysts (keeping the amount of Co added consistent), and the reaction conditions were the same. The results are shown in Table 1.

[0037] (3) Comparative Example 7: No urea was added during the preparation process, and the rest were the same. The resulting sample was recorded as S2. The reaction conditions were the same, and the results are shown in Table 1.

[0038] Table 1. Comparison of hydroformylation performance between the precatalyst of this invention and commercial Co-based materials.

[0039] As shown in Table 1, commercial Co3O4 and CoO, as well as S2 prepared without urea, exhibit almost no olefin hydroformylation activity under the same conditions. Although Co2O3 has some activity, its aldehyde selectivity is low, with the main product being an inner olefin that is isomerizes 1-octene. Traditional catalysts Co2(CO)8 and Co(OAc)2 both possess excellent olefin hydroformylation activity, but their aldehyde selectivity is still significantly lower than that of S1. Furthermore, the aldehydes obtained from Co2(CO)8 and Co(OAc)2 are predominantly isomers (N / I < 0.7), while S1 predominantly produces normal aldehydes.

[0040] Table 2. Recyclability performance of the precatalyst of this invention

[0041] The data in Table 2 show that the precatalyst described in this invention has good recycling performance.

[0042] Example 2 Using 2-octene as a substrate and the precatalyst S1 from Example 1, under the same reaction conditions, the conversion was >99% and the aldehyde selectivity was 55.1%.

[0043] Using diisobutylene as a substrate and precatalyst S1 from Example 1, the reaction was carried out for 6 h under the same conditions, with a conversion rate of ~95% and an aldehyde selectivity of 72.1%.

[0044] The reaction results of different substrate configurations show that the precatalyst of the present invention can be applied to a variety of olefin substrates with different configurations.

[0045] Example 3 Urea was replaced with amino-containing compounds such as ammonia, ethylenediamine, triethylamine, and ammonium acetate, respectively, and the rest was the same as in Example 1. The resulting pre-catalysts were named S3, S4, S5, and S6 in sequence.

[0046] The catalytic reaction was carried out for 4 hours, and other procedures were the same as in Example 1. The results are shown in Table 3.

[0047] Table 3. Hydroformylation performance of precatalysts under different precipitants

[0048] As shown in Table 3, the absence of a precipitant can affect the activity of the precatalyst. In conjunction with Example 1, urea is preferred.

[0049] Example 4 Ethanol, isopropanol, and ethylene glycol were used instead of water, and the rest was the same as in Example 1. The resulting precatalysts were named S7, S8, and S9 respectively.

[0050] The catalytic reaction was carried out under the same conditions as in Example 1, and the results are shown in Table 4.

[0051] Table 4. Hydroformylation performance of the precatalyst in different solvents

[0052] As shown in Table 4, the solvent has a significant impact on the performance of the precatalyst. Based on Example 1, water is preferred.

[0053] Example 5 Cobalt nitrate was replaced with cobalt acetate, cobalt chloride, cobalt carbonate, and cobalt oxalate respectively, and the rest was the same as in Example 1. The resulting pre-catalysts were successively named S10 (and S10-A250 when calcined in air), S11, S12, and S13.

[0054] The catalytic reaction was carried out under the same conditions as in Example 1, and the results are shown in Table 5.

[0055] Table 5. Precatalyst hydroformylation performance of different cobalt precursors

[0056] In Table 4, except for cobalt carbonate (S12), the dried products of the precatalysts prepared from the other precursors all exhibited characteristic diffraction peaks of the unknown cobalt compound, and after calcination, they were all dominated by Co3O4. The dried and calcined products of cobalt carbonate (S12) only showed the phase characteristics of cobalt carbonate, and no diffraction signals of the unknown cobalt compound or Co3O4 were observed. However, it still exhibited certain hydroformylation catalytic activity (conversion >99%, aldehyde selectivity 35.1%), indicating that the cobalt carbonate precursor may form catalytically active species through a mechanism different from the aforementioned phase evolution pathways.

[0057] Example 6 (1) Experimental methods Pre-catalyst preparation: 1.0 g Co(NO3)2·6H2O, 0.5 g urea, and 1 g support were dissolved in 50 mL deionized water and transferred to a 100 mL hydrothermal reactor. The mixture was reacted at 100 °C for 12 h. After cooling, the mixture was centrifuged, washed three times each with water and ethanol, and dried at 120 °C for 4 h. Then, it was treated at 250 °C for 4 h under a N2 atmosphere and allowed to cool naturally to obtain a black powder. When the support was activated carbon, ZSM-5, Al2O3, or SiO2, it was designated as S14(350)2·6H2O. o C roasting is designated as S14-350), S15, S16, and S17.

[0058] The reaction was carried out with a catalyst dosage of 20 mg, and the other steps were the same as in Example 1. The results are shown in Table 6.

[0059] (2) Comparative Example 1: Preparation of precatalyst by mechanical grinding. 1.0 g Co(NO3)2·6H2O, 0.5 g urea and 1 g activated carbon were mixed and ground evenly, and treated at 250 °C for 4 h under N2 atmosphere. After natural cooling, a black powder was obtained, which was denoted as S18.

[0060] (3) Comparative Example 2: Precatalyst prepared by ethanol reflux method. 1.0 g Co(NO3)2·6H2O, 0.5 g urea and 1 g activated carbon were refluxed in 50 mL ethanol for 12 h, cooled and centrifuged, washed three times each with water and ethanol, and dried at 120 °C for 4 h. It was then treated at 250 °C for 4 h under N2 atmosphere and cooled naturally to obtain a black powder, denoted as S19.

[0061] (3) Comparative Example 3: Precatalyst prepared by impregnation method. 1.0 g Co(NO3)2·6H2O, 0.5 g urea and 1 g activated carbon were stirred in 5 mL deionized water at room temperature for 4 h, and then allowed to stand for 2 h. o Dry at C for 4 h. Then, treat at a constant temperature of 250 °C for 4 h under N2 atmosphere, and allow to cool naturally to obtain a black powder, denoted as S20.

[0062] (4) Comparative Example 4: Precatalyst prepared by deposition precipitation method. 1.0 g Co(NO3)2·6H2O, 0.5 g urea and 1 g activated carbon were stirred evenly in 50 mL deionized water and heated to 80°C. o C, stir at constant temperature for 4 h. After cooling, centrifuge, wash three times each with water and ethanol, and dry at 120 °C for 4 h. Treat at constant temperature of 250 °C for 4 h under N2 atmosphere, and cool naturally to obtain a black powder, denoted as S21.

[0063] In the comparative example, S18~S21 reacted under the same conditions, and the results are shown in Table 6.

[0064] Table 6. Hydroformylation performance of supported precatalysts and precatalysts prepared by non-supported methods

[0065] As shown in the first five rows of Table 6, the supported precatalyst also exhibits good hydroformylation performance, and generally has a better N / I ratio. As a precatalyst, the support improves the dispersion of Co species and promotes the formation of active species, thus making it a viable option. There are certain differences between different supports, with activated carbon being the preferred choice.

[0066] The last four rows of Table 6 show that, as long as cobalt salts and urea (or amino compounds) are present, different preparation methods can obtain a certain degree of hydroformylation activity, but their performance is far lower than that of the solvothermal method used in this invention.

Claims

1. A cobalt-based hydroformylation precatalyst, characterized in that, The product is prepared by a method including the following steps: mixing a cobalt precursor with an amino-containing compound in a solvent and carrying out a solvothermal reaction; the resulting product is then subjected to solid-liquid separation, dried, and then subjected to an inert atmosphere or air atmosphere at 200-450°C. o The precatalyst was obtained by calcination at C. The raw materials used in the preparation method consist only of cobalt precursor, amino-containing compound and solvent, without any added organic ligands and without precious metal elements.

2. The precatalyst according to claim 1, characterized in that, The phase of the precatalyst is one or more of the following (a), (b), (c), and (d): (a) Co3O4, whose X-ray diffraction pattern shows characteristic diffraction peaks of Co3O4; (b) CoO, whose X-ray diffraction pattern shows characteristic diffraction peaks of CoO; (c) A cobalt compound having characteristic diffraction peaks in its X-ray diffraction pattern at 2θ angles of 14.6 °±0.2 °, 17.3 °±0.2 °, 23.9 °±0.2 °, 29.3 °±0.2 °, 30.9 °±0.2 °, 34.6 °±0.2 °, 35.2 °±0.2 °, 36.3 °±0.2 °, 38.1 °±0.2 ° and 41.8 °±0.2 °; (d) CoCO3, whose X-ray diffraction pattern shows characteristic diffraction peaks of CoCO3.

3. The precatalyst according to claim 1, characterized in that, The precatalyst is prepared from a cobalt precursor via solvothermal reaction and calcination, and satisfies the following phase evolution characteristics: The dried product of the cobalt precursor after solvothermal reaction and before calcination is mainly composed of the cobalt compound phase described in claim 2, and mainly composed of Co3O4 phase after calcination; wherein the cobalt precursor does not include cobalt carbonate; the precatalyst is prepared by solvothermal reaction using cobalt carbonate as a precursor, and retains the cobalt carbonate phase before and after calcination.

4. The precatalyst according to claim 1, characterized in that, The precatalyst is heated at ≥100°C in a syngas atmosphere. o C. Treatment under pressure ≥2 MPa can generate a Co-CO structure, whose infrared spectrum is in the range of 2000~2143 cm⁻¹. -1 2143~2250cm -1 Two sets of CO adsorption characteristic peaks appeared in the region.

5. The precatalyst according to claim 1, characterized in that, The solvothermal reaction temperature is 100~200℃. o C, the reaction time is 6~72 hours; the drying temperature is 60~120℃. o C; The roasting time is 2 to 6 hours.

6. The precatalyst according to claim 1, characterized in that, The cobalt precursor is selected from one or more of cobalt nitrate, cobalt acetate, cobalt carbonate, cobalt chloride, and cobalt oxalate; the amino-containing compound is selected from one or more of urea, ammonia, ethylenediamine, triethylamine, and ammonium acetate; the molar ratio of the cobalt precursor to the amino-containing compound is 1:0.5 to 1:3; the solvent is selected from one or more of water, methanol, ethanol, and isopropanol.

7. A method for olefin hydroformylation reaction using the precatalyst according to any one of claims 1 to 6, characterized in that, The precatalyst according to any one of claims 1 to 6, the olefin substrate, CO, and H2 are added to the reactor, and the mixture is heated at a temperature of 120 to 180°C. o C. The reaction is carried out under conditions of pressure 2~6 MPa and H2 / CO molar ratio 0.5~2, wherein the catalyst is converted in situ into active species to catalyze the reaction during the process; after the reaction, the catalyst is placed at <60 °C. o The product is separated by vacuum distillation at C, and the cobalt-containing residue obtained can be directly recycled for the next reaction; the olefin substrate is selected from one or more of 1-octene, 2-octene, and diisobutylene.

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