Co3O4 catalyst, Fe-Co3O4 catalyst and preparation method and application thereof

Abstract

The invention discloses a Co3O4 catalyst, a Fe-Co3O4 catalyst as well as a preparation method and application of the Co3O4 catalyst and the Fe-Co3O4 catalyst, and belongs to the technical field of catalysts. The preparation method comprises the following steps: firstly, preparing a Co3O4 catalyst with a specific needle-shaped morphology, exposing a crystal face to be a (110) crystal face, and then doping heteroatom Fe into the needle-shaped Co3O4 catalyst, so that the content of oxygen vacancies and the specific surface area are greatly improved; compared with the existing catalyst, the catalyst has the advantages that the esterification reaction effect is better, the yield can reach 89.365%, the catalyst has high mechanical strength and thermal stability, and stable recycling of the catalyst in a continuous process can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a Co3O4 catalyst, an Fe-Co3O4 catalyst, and their preparation methods and applications. Background Art

[0002] Disclosing the information of this background art section is only intended to increase the understanding of the overall background of the present invention, and is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Ethoxyethoxyethyl acrylate (CAS No. 7328-17-8) is a colorless transparent liquid at normal temperature and pressure. It is insoluble in water but miscible with common organic solvents such as ethyl acetate, dichloromethane, chloroform, etc. It has high chemical reactivity, excellent low-temperature flexibility, good diluting power, good weather resistance, good adhesion, anti-solubility, low shrinkage and high hardness. It is often used in the manufacture of optical materials, packaging materials, coatings and adhesives, etc., and can be used as an acrylate monomer to participate in copolymerization or cross-linking reactions in polymerization reactions for the preparation of various polymers and polymer materials. It can also be used in pharmaceutical chemistry and pesticide production.

[0004] Industrially, ethoxyethoxyethyl acrylate is mostly prepared by the esterification reaction of acrylic acid and diethylene glycol monoethyl ether. Traditional esterification reactions mostly use liquid acid catalysts such as concentrated sulfuric acid and p-toluenesulfonic acid. Although they have high catalytic activity, they have problems such as serious equipment corrosion, non-recyclable catalysts, and complex product post-treatment. Although the solid acid catalysts developed in recent years can alleviate the corrosion problem, they generally have defects such as easy loss of acidic sites, poor thermal stability, and difficulty in forming, which easily lead to catalyst deactivation and product selectivity decline during continuous production. Existing metal oxide catalysts (such as alumina, titanium oxide, etc.) often show limitations such as insufficient acid strength and low specific surface area in the esterification reaction, resulting in low reaction efficiency. Summary of the Invention

[0005] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a Co3O4 catalyst, an Fe-Co3O4 catalyst, and their preparation methods and applications. The Co3O4 catalyst and the Fe-Co3O4 catalyst have a high defect and high specific surface area for use in the esterification reaction to prepare ethoxyethoxyethyl acrylate. This method first prepares a Co3O4 catalyst with a specific needle-like morphology, and then incorporates the heteroatom Fe into the needle-like Co3O4 catalyst, thereby greatly increasing the content of oxygen vacancies and the specific surface area. This preparation method is simple to operate, can greatly improve the catalytic activity of the catalyst, and this method has good versatility.

[0006] The present invention innovatively develops Co3O4 catalysts and Fe-Co3O4 catalysts with high specific surface area and rich oxygen vacancy content. The high specific surface area can significantly improve the mass transfer efficiency, and the abundant oxygen vacancies on the surface can effectively adsorb and activate carboxylic acid and hydroxyl components. As Figure 5 shown are the test results of the Fe-Co3O4 catalyst running continuously for 148 hours. As shown in the figure, the conversion rate of the catalyst during operation is stable above 86%, indicating that the catalyst has both high mechanical strength and thermal stability, can realize the stable recycling of the catalyst in the continuous process, and is significantly superior to the existing solid acid catalytic system. In addition, the non-toxic and environmentally friendly characteristics of Co3O4 meet the requirements of the development of green chemistry and provide an innovative solution for the industrial production of high-performance ester compounds.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] In the first aspect, the present invention provides a preparation method of a Co3O4 catalyst, comprising the following steps:

[0009] Ammonia water and alcohol are mixed to form solution A, a cobalt source is dissolved in water to form solution B, a sodium carbonate solution and solution B are successively added to solution A to obtain a mixed solution, which is subjected to hydrothermal reaction, washed and dried, and then calcined to obtain the product.

[0010] Preferably, the alcohol is ethylene glycol.

[0011] Preferably, the cobalt source is Co(NO3)2·6H2O.

[0012] Preferably, the ratio of ammonia water, alcohol, cobalt source, water, and sodium carbonate solution is (5 - 15 ml):(20 - 30 ml):(1 - 5 g):(4 - 6 ml):(1 - 3 ml), preferably (5 - 15 ml):(20 - 30 ml):(1 - 2 g):(4 - 6 ml):(1 - 3 ml).

[0013] The function of adding ammonia water and ethylene glycol is that ammonia water complexes with metal ions to generate Co(OH)2 crystal nuclei, which is beneficial to the subsequent growth of crystals and facilitates the formation of Co3O4 catalysts by subsequent calcination. The cooperation of ethylene glycol and ammonia water can provide a mild reduction environment, thereby helping the catalyst to generate more surface defects and Lewis acid sites while maintaining the needle-like morphology.

[0014] Preferably, the concentration of the sodium carbonate solution is 1 - 3 M.

[0015] The function of adding the sodium carbonate solution is to induce the growth of Co3O4 along the needle-like morphology and expose the 110 crystal plane (the TEM test results can prove that the main exposed crystal plane of the catalyst is the 110 crystal plane).

[0016] Preferably, during the process of mixing ammonia water and alcohol to form solution A, stir for 20 - 60 min.

[0017] Preferably, during the process of dissolving the cobalt source in water to form solution B, stir for 20 - 60 min.

[0018] Preferably, during the process of adding the sodium carbonate solution and solution B to solution A in sequence to obtain a mixed solution, stir for 20 - 60 min.

[0019] Preferably, in the hydrothermal reaction, the hydrothermal temperature is 150 - 200 °C, preferably 160 - 180 °C, and the hydrothermal reaction time is 10 - 20 h, preferably 15 - 20 h. The temperature cannot be lower than 150 °C. A lower reaction temperature will cause the Co3O4 crystal grains to finally grow into a sheet structure and make its main exposed crystal plane become the 112 crystal plane instead of the 110 crystal plane of the needle-like morphology. The main exposed crystal plane of the catalyst obtained by the preparation method of the present invention is the 110 crystal plane. The temperature can reach up to 200 °C at most, but to ensure the generation of the needle-like morphology of the 110 exposed crystal plane, the optimal reaction temperature is 170 °C.

[0020] Preferably, after the hydrothermal reaction, the reaction solution is washed until the pH = 6 - 8, preferably pH = 7; the drying conditions are drying at 50 - 70 °C for 10 - 15 h.

[0021] Preferably, during the calcination process, the heating rate is 4 - 7 °C / min, the calcination temperature is 250 - 350 °C, preferably 290 - 310 °C, and the calcination time is 2 - 6 h, preferably 2 - 4 h.

[0022] In the second aspect, the present invention provides a Co3O4 catalyst obtained by the above preparation method.

[0023] The Co3O4 catalyst is a nanoscale cubic spinel structure, with a needle-like morphology, and the exposed crystal plane is the (110) crystal plane.

[0024] The specific surface area of the Co3O4 catalyst is 40 - 50 m 2 / g.

[0025] In the third aspect, the present invention provides a preparation method of an Fe-Co3O4 catalyst, including the following steps:

[0026] Mix ammonia water and alcohol to form solution A, dissolve the cobalt source and iron source in water to form solution B, add the sodium carbonate solution and solution B to solution A in sequence to obtain a mixed solution, carry out hydrothermal reaction, then wash and dry, and finally calcine to obtain.

[0027] Preferably, the alcohol is ethylene glycol.

[0028] Preferably, the cobalt source is Co(NO3)2·6H2O; the iron source is Fe(NO3)3·9H2O.

[0029] Preferably, the ratio of ammonia water, alcohol, cobalt source, water, and sodium carbonate solution is (5 - 15 ml):(20 - 30 ml):(1 - 5 g):(4 - 6 ml):(1 - 3 ml), preferably (5 - 15 ml):(20 - 30 ml):(1 - 2 g):(4 - 6 ml):(1 - 3 ml).

[0030] The doping amount of Fe is 0.5% - 1.5% of the mass of the Co3O4 catalyst, preferably 1%.

[0031] Preferably, the concentration of the sodium carbonate solution is 1 - 3 M.

[0032] Preferably, during the process of mixing ammonia water and alcohol to form solution A, stir for 20 - 60 min.

[0033] Preferably, during the process of dissolving the cobalt source in water to form solution B, stir for 20 - 60 min.

[0034] Preferably, during the process of adding the sodium carbonate solution and solution B to solution A in sequence to obtain a mixed solution, stir for 20 - 60 min.

[0035] Preferably, in the hydrothermal reaction, the hydrothermal temperature is 150 - 200 °C, preferably 160 - 180 °C, and the hydrothermal reaction time is 10 - 20 h, preferably 15 - 20 h.

[0036] Preferably, the reaction solution after the hydrothermal reaction is washed until the pH = 6 - 8; the drying conditions are drying at 50 - 70 °C for 10 - 15 h.

[0037] Preferably, during the calcination process, the heating rate is 4 - 7 °C / min, the calcination temperature is 250 - 350 °C, preferably 290 - 310 °C, and the calcination time is 2 - 6 h, preferably 2 - 4 h.

[0038] Fourthly, the present invention provides an Fe-Co3O4 catalyst obtained by the above preparation method. The Fe-Co3O4 catalyst has a nanoscale cubic spinel structure, the morphology is a needle-like structure, and the exposed crystal plane is the (110) crystal plane. The specific surface area of the Fe-Co3O4 catalyst is 50 - 60 m 2 / g.

[0039] Fifthly, the present invention provides the application of the above Co3O4 catalyst or Fe-Co3O4 catalyst in the esterification reaction.

[0040] Preferably, the esterification reaction is used for preparing acrylate derivatives.

[0041] In a sixth aspect, the present invention provides a method for preparing ethoxyethoxyethyl acrylate, comprising the following steps:

[0042] Using acrylic acid and diethylene glycol ethyl ether as the reaction solution, cyclohexane as the water-carrying agent, and hydroquinone as the polymerization inhibitor, react with the above-mentioned Co3O4 catalyst or Fe-Co3O4 catalyst.

[0043] Preferably, the reaction time is 6 - 10 h, more preferably 7 - 9 h, and the reaction temperature is 80 - 120 °C, more preferably 90 - 110 °C.

[0044] Preferably, the molar ratio of acrylic acid to diethylene glycol ethyl ether is 1 - 1.5:1, more preferably 1.1 - 1.2:1.

[0045] Preferably, the addition amount of cyclohexane is 20 - 40% of the total mass of the reaction solution, more preferably 25 - 35%.

[0046] Preferably, the addition amount of hydroquinone is 0.5 - 5% of the total mass of the reaction solution, more preferably 0.8 - 2%.

[0047] Preferably, the addition amount of the catalyst is 2 - 10% of the total mass of the reaction solution, more preferably 4 - 6%.

[0048] One or some of the above technical solutions have the following advantages or beneficial effects:

[0049] (1) The present invention provides a method for preparing a Co3O4 catalyst and an Fe-Co3O4 catalyst for esterification reaction. This method is simple to operate and the conditions are easy to control. By simply doping heteroatoms into the specific needle-shaped morphology cobalt tetroxide catalyst, a cobalt tetroxide catalyst with a higher oxygen vacancy content is obtained.

[0050] (2) The catalyst prepared by the method of the present invention has a larger specific surface area and more surface defects, thus showing more excellent esterification reaction performance.

[0051] (3) In addition, due to its simple and easily available raw materials, simple and easy-to-operate preparation method, low cost, non-toxicity, and environmental friendliness, it is suitable for industrial applications.

[0052] (4) Compared with the catalysts used in the prior art for preparing ethoxyethoxyethyl acrylate, such as p-toluenesulfonic acid or methanesulfonic acid, the Co3O4 catalyst and Fe-Co3O4 catalyst provided by the present invention have a higher yield in the esterification reaction for preparing ethoxyethoxyethyl acrylate; and this catalyst has both high mechanical strength and thermal stability, and can realize the stable recycling of the catalyst in the continuous process.

[0053] (5) When using the heteroatom-doped Co3O4 catalyst to prepare ethoxyethoxyethyl acrylate, compared with the catalysts doped with other atoms such as copper atoms (yield 80.621%), the catalyst Fe-Co3O4 doped with iron atoms (yield 89.365%) can achieve better results. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The accompanying drawings forming a part of this invention are used to provide a further understanding of the invention. The schematic embodiments and descriptions thereof of the invention are used to explain the invention and shall not unduly limit the invention.

[0055] Figure 1 SEM image of the Co3O4 catalyst prepared in Example 1 of the present invention;

[0056] Figure 2 TEM image of the Co3O4 catalyst prepared in Example 1 of the present invention;

[0057] Figure 3 XRD spectra of the Co3O4 catalyst prepared in Example 1 of the present invention and the Fe-Co3O4 catalyst prepared in Example 2;

[0058] Figure 4 XPS spectra of the Co3O4 catalyst prepared in Example 1 of the present invention and the Fe-Co3O4 catalyst prepared in Example 2;

[0059] Figure 5 Stability test results of the Fe-Co3O4 catalyst prepared in Example 2 of the present invention when used to prepare ethoxyethoxyethyl acrylate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0060] All reagents used in the present invention are commercially available.

[0061] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0062] Preparation of Co3O4 Catalyst in Example 1

[0063] 10 mL of ammonia water and 25 mL of ethylene glycol were poured into a 50 mL beaker and stirred for 30 min to form Solution A. 1.4551 g of Co(NO3)2·6H2O was dissolved in 5 mL of deionized water and stirred for 30 min to form Solution B. 1.5 mL of a 1 M sodium carbonate solution was added to Solution A, and then Solution B was dropped into Solution A, and then stirring was continued for 30 min. Then the above-dispersed solution was transferred to a stainless-steel autoclave and hydrothermally reacted at 170 °C for 17 hours. After the reaction was completed and cooled to room temperature, the pink suspension was washed thoroughly until the pH = 7 and dried overnight. The dried pink solid was calcined at 300 °C for 3 hours. Finally, the Co3O4 catalyst was prepared.

[0064] Figure 1 SEM image of the needle-shaped Co3O4 catalyst with a specific morphology prepared in Example 1, Figure 1 showing the morphology of the Co3O4 catalyst.

[0065] Figure 2 TEM image of the needle-shaped Co3O4 catalyst with a specific morphology prepared in Example 1, Figure 2 The results in it show that the exposed crystal plane of the catalyst is the (110) crystal plane perpendicular to the (220) crystal plane and the (111) crystal plane.

[0066] Preparation of the Fe-Co3O4 catalyst with a doping amount of 1% in Example 2

[0067] 10 mL of ammonia water and 25 mL of ethylene glycol were poured into a 50 mL beaker and stirred for 30 min to form Solution A. 1.4551 g of Co(NO3)2·6H2O and 0.03 g of Fe(NO3)3·9H2O were dissolved in 5 mL of deionized water and stirred for 30 min to form Solution B. 1.5 mL of a 1 M sodium carbonate solution was added to Solution A, and then Solution B was dropped into Solution A, and then stirring was continued for 30 min. Then the above-dispersed solution was transferred to a stainless-steel autoclave and hydrothermally reacted at 170 °C for 17 hours. After the reaction was completed and cooled to room temperature, the suspension was washed thoroughly until the pH = 7 and dried overnight. The dried solid was calcined at 300 °C for 3 hours. Finally, the Fe-Co3O4 catalyst was prepared.

[0068] Example 3 Preparation of ethoxyethoxyethyl acrylate using the Co3O4 catalyst

[0069] A certain amount of reaction solution was added to a flask and mixed evenly. The molar ratio of acrylic acid to diethylene glycol ethyl ether in the reaction solution was 1.1:1. Cyclohexane accounting for 30% of the total mass of the reaction solution was added as a water-carrying agent, hydroquinone accounting for 1% of the total mass of the reaction solution was added as an inhibitor, and Co3O4 prepared in Example 1 accounting for 5% of the total mass of the reaction solution was added as a catalyst. The reaction temperature was 100 °C and the reaction time was 8 hours. After cooling, a sample was taken. Analysis proved that the yield of ethoxyethoxyethyl acrylate was 78.574%.

[0070] Example 4 Preparation of ethoxyethoxyethyl acrylate using Fe-Co3O4 catalyst

[0071] A certain amount of reaction solution was added to a flask and mixed evenly. The molar ratio of acrylic acid to diethylene glycol ethyl ether in the reaction solution was 1.1:1. Cyclohexane accounting for 30% of the total mass of the reaction solution was added as a water-carrying agent, hydroquinone accounting for 1% of the total mass of the reaction solution was added as an inhibitor, and Fe-Co3O4 prepared in Example 2 accounting for 5% of the total mass of the reaction solution was added as a catalyst. The reaction temperature was 100 °C and the reaction time was 8 hours. After cooling, a sample was taken. Analysis proved that the yield of ethoxyethoxyethyl acrylate was 89.365%.

[0072] Figure 2 XRD patterns of the Co3O4 catalyst prepared in Example 1 and the Fe-Co3O4 catalyst prepared in Example 2. From Figure 2 it can be seen that after doping with a trace amount of heteroatom Fe, the crystal phase of the catalyst did not change, and the prepared catalysts were all typical spinel Co3O4 structures.

[0073] Figure 3 XPS spectra of the Co3O4 catalyst prepared in Example 1 and the Fe-Co3O4 catalyst prepared in Example 2, where O2 represents oxygen vacancies. From Figure 3 it can be seen that the oxygen vacancy content of the treated catalyst has increased significantly.

[0074] Table 1

[0075]

[0076] Table 1 shows the specific surface areas of the Co3O4 catalyst prepared in Example 1 and the Fe-Co3O4 catalyst prepared in Example 2. It can be seen from Table 1 that the specific surface area of the catalyst doped with a trace amount of heteroatom Fe has increased significantly.

[0077] Comparative Example 1 Preparation of ethoxyethoxyethyl acrylate using p-toluenesulfonic acid as a catalyst

[0078] A certain amount of reaction solution was added to a flask and mixed evenly. The molar ratio of acrylic acid to diethylene glycol ethyl ether in the reaction solution was 1.1:1. Cyclohexane accounting for 30% of the total mass of the reaction solution was added as a water-carrying agent, hydroquinone accounting for 1% of the total mass of the reaction solution was added as an inhibitor, and p-toluenesulfonic acid accounting for 5% of the total mass of the reaction solution was added as a catalyst. The reaction temperature was 100 °C and the reaction time was 8 hours. After cooling, a sample was taken. Analysis proved that the yield of ethoxyethoxyethyl acrylate was 62.656%.

[0079] Comparative Example 2 Methanesulfonic acid was used as a catalyst in the preparation of ethoxyethoxyethyl acrylate

[0080] A certain amount of reaction solution was added to a flask and mixed evenly. The molar ratio of acrylic acid to diethylene glycol ethyl ether in the reaction solution was 1.1:1. Cyclohexane accounting for 30% of the total mass of the reaction solution was added as a water-carrying agent, hydroquinone accounting for 1% of the total mass of the reaction solution was added as an inhibitor, and methanesulfonic acid accounting for 5% of the total mass of the reaction solution was added as a catalyst. The reaction temperature was 100 °C and the reaction time was 8 hours. After cooling, a sample was taken. Analysis proved that the yield of ethoxyethoxyethyl acrylate was 68.193%.

[0081] Comparative Example 3

[0082] 10 mL of ammonia water and 25 mL of ethylene glycol were poured into a 50 mL beaker and stirred for 30 min to form Solution A. 1.4551 g of Co(NO3)2·6H2O and 0.016 g of Cu(NO3)2·3H2O were dissolved in 5 mL of deionized water and stirred for 30 min to form Solution B. 1.5 mL of a 1 M sodium carbonate solution was added to Solution A, and then Solution B was dropped into Solution A, and then stirring was continued for 30 min. Then the above-dispersed solution was transferred to a stainless steel autoclave and hydrothermally reacted at 170 °C for 17 hours. After the reaction ended and cooled to room temperature, the suspension was washed thoroughly until pH = 7 and dried overnight. The dried solid was calcined at 300 °C for 3 hours. Finally, the Cu-Co3O4 catalyst was prepared.

[0083] A certain amount of reaction solution was added to a flask and mixed evenly. The molar ratio of acrylic acid to diethylene glycol ethyl ether in the reaction solution was 1.1:1. Cyclohexane accounting for 30% of the total mass of the reaction solution was added as a water-carrying agent, hydroquinone accounting for 1% of the total mass of the reaction solution was added as an inhibitor, and the Cu-Co3O4 prepared in Example 2 accounting for 5% of the total mass of the reaction solution was added as a catalyst. The reaction temperature was 100 °C and the reaction time was 8 hours. After cooling, a sample was taken. Analysis proved that the yield of ethoxyethoxyethyl acrylate was 80.621%.

[0084] Table 2

[0085]

[0086] From the comparison between the examples and the comparative examples shown in Table 2, it can be seen that the prepared Fe-Co3O4 catalyst has a significantly better yield of ethoxyethoxyethyl acrylate than the traditional p-toluenesulfonic acid catalyst and methanesulfonic acid catalyst. This may be because the abundant oxygen vacancies on the surface of Co3O4 form local electron defect regions, significantly enhancing the electron migration ability on the catalyst surface. Figure 3 The XPS results in [reference] show that the prepared catalysts all have abundant oxygen vacancies. The carboxyl group (-COOH) of acrylic acid is preferentially adsorbed on the Co 3+ sites adjacent to the oxygen vacancies. Through the strong polarization of the Lewis acid sites, the lone pair electrons of the carboxyl oxygen are transferred to Co 3+ , resulting in a decrease in the electron cloud density of the C=O double bond and an increase in the electrophilicity of the carbonyl carbon, thus reducing the reaction activation energy. The hydroxyl group (-OH) of diethylene glycol ethyl ether is adsorbed on the basic sites (O 2- or Co 2+ -O - ) on the surface of Co3O4, and deprotonation occurs to generate a more nucleophilic alkoxy group (-O - ), significantly improving the nucleophilic attack efficiency. The oxygen vacancies act as a "bridge" for proton transfer, assisting the rapid transfer of the hydroxyl proton (H + ) of the carboxyl group of acrylic acid to the oxygen atom of the alkoxy group, forming a tetrahedral intermediate. The high specific surface area can provide abundant active sites, ensuring the directional arrangement of acrylic acid molecules and diethylene glycol ethyl ether, reducing steric hindrance, and increasing the formation rate of the transition state. In addition, the generated H2O molecules are preferentially adsorbed in the oxygen vacancy region and rapidly desorbed through the weak binding energy of the oxygen vacancies to the H2O, breaking the equilibrium limitation of the esterification reaction and promoting the reaction towards the product direction. During the reaction process, the Co 3+ / Co 2+ redox pair repairs the surface oxygen vacancies through dynamic electron transfer to maintain the stability of the catalytic active sites. Due to the above advantages, the catalyst prepared by the present invention has extremely excellent catalytic efficiency for the esterification reaction.

[0087] From the comparison between Example 4 and Comparative Example 3, it can be seen that Fe doping has a more excellent catalytic efficiency for the esterification reaction than Cu doping, and the performance of the catalyst does not improve significantly after Cu doping. This may be because although Cu doping can also increase the content of oxygen vacancies in the catalyst, it will also annihilate the Lewis acid sites on the catalyst surface. On the contrary, Fe doping can not only increase the content of oxygen vacancies in the catalyst, but also increase the content of Lewis acid sites in the catalyst. The Lewis acid sites are also extremely important for the catalyst to catalyze the esterification reaction of diethylene glycol ethyl ether and acrylic acid. Therefore, not all heteroatoms can achieve the same effect as Fe doping.

[0088] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a Co3O4 catalyst, characterized in that, It includes the following steps: Ammonia water and alcohol are mixed to form solution A, a cobalt source is dissolved in water to form solution B, a sodium carbonate solution and solution B are successively added to solution A to obtain a mixed solution, which is subjected to hydrothermal reaction, washed and dried, and then calcined to obtain the product.

2. The preparation method according to claim 1, characterized in that, The alcohol is ethylene glycol; Preferably, the cobalt source is Co(NO3)2·6H2O; Preferably, the ratio of ammonia water, alcohol, cobalt source, water, and sodium carbonate solution is (5 - 15 ml):(20 - 30 ml):(1 - 5 g):(4 - 6 ml):(1 - 3 ml), preferably (5 - 15 ml):(20 - 30 ml):(1 - 2 g):(4 - 6 ml):(1 - 3 ml); Preferably, the concentration of the sodium carbonate solution is 1 - 3 M; Preferably, during the process of mixing ammonia water and alcohol to form solution A, stirring is carried out for 20 - 60 min; Preferably, during the process of dissolving the cobalt source in water to form solution B, stirring is carried out for 20 - 60 min; Preferably, during the process of successively adding the sodium carbonate solution and solution B to solution A to obtain a mixed solution, stirring is carried out for 20 - 60 min; Preferably, in the hydrothermal reaction, the hydrothermal temperature is 150 - 200 °C, preferably 160 - 180 °C, and the hydrothermal reaction time is 10 - 20 h, preferably 15 - 20 h; Preferably, the reaction solution after hydrothermal reaction is washed until the pH = 6 - 8; the drying condition is drying at 50 - 70 °C for 10 - 15 h; Preferably, during the calcination process, the heating rate is 4 - 7 °C / min, the calcination temperature is 250 - 350 °C, preferably 290 - 310 °C, and the calcination time is 2 - 6 h, preferably 2 - 4 h.

3. A Co3O4 catalyst, characterized in that, Obtained by the preparation method described in claim 1 or 2.

4. The Co3O4 catalyst according to claim 1, wherein The Co3O4 catalyst is a nanoscale cubic spinel structure, with a needle-like morphology, and the exposed crystal plane is the (110) crystal plane; Preferably, the specific surface area of the Co3O4 catalyst is 40-50 m 2 / g.

5. A preparation method of a Fe-Co3O4 catalyst, characterized in that, It includes the following steps: Ammonia water and alcohol are mixed to form solution A, a cobalt source and an iron source are dissolved in water to form solution B, a sodium carbonate solution and solution B are successively added to solution A to obtain a mixed solution, which is subjected to hydrothermal reaction, washed and dried, and then calcined to obtain the product.

6. The Fe-Co3O4 catalyst according to claim 1, wherein The alcohol is ethylene glycol; Preferably, the cobalt source is Co(NO3)2·6H2O; the iron source is Fe(NO3)3·9H2O; Preferably, the ratio of ammonia water, alcohol, cobalt source, water, and sodium carbonate solution is (5 - 15 ml):(20 - 30 ml):(1 - 5 g):(4 - 6 ml):(1 - 3 ml), preferably (5 - 15 ml):(20 - 30 ml):(1 - 2 g):(4 - 6 ml):(1 - 3 ml); Preferably, the doping amount of Fe is 0.5% - 1.5% of the mass of the Co3O4 catalyst, preferably 1%; Preferably, the concentration of the sodium carbonate solution is 1 - 3 M; Preferably, during the process of mixing ammonia water and alcohol to form solution A, stirring is carried out for 20 - 60 min; Preferably, during the process of dissolving the cobalt source in water to form solution B, stirring is carried out for 20 - 60 min; Preferably, during the process of successively adding the sodium carbonate solution and solution B to solution A to obtain a mixed solution, stirring is carried out for 20 - 60 min; Preferably, in the hydrothermal reaction, the hydrothermal temperature is 150 - 200 °C, preferably 160 - 180 °C, and the hydrothermal reaction time is 10 - 20 h, preferably 15 - 20 h; Preferably, the reaction solution after the hydrothermal reaction is washed until the pH = 6 - 8; the drying condition is drying at 50 - 70 °C for 10 - 15 h; Preferably, during the calcination process, the heating rate is 4 - 7 °C / min, the calcination temperature is 250 - 350 °C, preferably 290 - 310 °C, and the calcination time is 2 - 6 h, preferably 2 - 4 h.

7. A Fe-Co3O4 catalyst, characterized in that, Obtained by the preparation method according to claim 5 or 6; Preferably, the Fe-Co3O4 catalyst is a nanoscale cubic spinel structure, the morphology is a needle-like structure, and the exposed crystal plane is the (110) crystal plane; Preferably, the specific surface area of the Fe-Co3O4 catalyst is 50-60 m 2 / g.

8. Use of the Co3O4 catalyst according to claim 3 or 4 or the Fe-Co3O4 catalyst according to claim 7 in an esterification reaction; Preferably, the esterification reaction is used to prepare acrylate derivatives.

9. A method for preparing ethoxyethoxyethyl acrylate, characterized in that, Comprising the following steps: Using acrylic acid and diethylene glycol ethyl ether as the reaction solution, cyclohexane as the water-carrying agent, hydroquinone as the polymerization inhibitor, and adding the Co3O4 catalyst according to claim 3 or 4 or the Fe-Co3O4 catalyst according to claim 7 for reaction.

10. The preparation method according to claim 9, characterized in that, The reaction time is 6 - 10 h, and the reaction temperature is 80 - 120 °C; Preferably, the molar ratio of acrylic acid to diethylene glycol ethyl ether is 1 - 1.5:1; Preferably, the addition amount of cyclohexane is 20 - 40% of the total mass of the reaction solution; Preferably, the addition amount of hydroquinone is 0.5 - 5% of the total mass of the reaction solution; Preferably, the addition amount of the catalyst is 2 - 10% of the total mass of the reaction solution.

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