Catalyst and preparation method thereof, and cyclododecatriene catalytic epoxidation method

Abstract

The invention relates to a catalyst, a preparation method thereof and a cyclododecatriene catalytic epoxidation method, graphene powder is added into preparation raw materials of the catalyst, so that the obtained catalyst has proper and ordered mesopores and macropores, and the reactivity center accessibility and diffusion performance of the catalyst are effectively improved; when the catalyst is used in the epoxidation reaction of macrocycloolefin, the catalytic reaction activity and the activity stability which are remarkably improved and the selectivity to a target product are favorably obtained.

Description

Technical Field

[0001] This disclosure relates to a catalyst and its preparation method, and a method for catalytic epoxidation of cyclododecanetriene. Background Technology

[0002] With the rapid development of science and technology, the epoxidation technology of macrocyclic olefins has been continuously advancing and has received increasing attention. Among them, cyclododecanetriene is one of the main macrocyclic polyolefins produced in the petrochemical production process. It is an important organic chemical raw material with broad application prospects, and the products obtained from its epoxidation have high industrial value.

[0003] In the oxidation reaction of organic matter, titanium silicate molecular sieves can catalyze a variety of organic oxidation reactions as oxidation catalysts. They have the advantages of simple process, energy saving, economy and environmental friendliness. However, due to their pore characteristics, they are difficult to apply to the oxidation of cyclic macromolecules such as cyclododecanetriene. Summary of the Invention

[0004] The purpose of this disclosure is to provide a catalyst suitable for the epoxidation of macrocyclic olefins and its preparation method, as well as a method for the catalytic epoxidation of cyclododecanetrienes.

[0005] To achieve the above objectives, the first aspect of this disclosure provides a method for preparing a catalyst, the method comprising:

[0006] A silicon source, a titanium source, an organic template agent, graphene powder, and water are mixed to obtain a mixed slurry; wherein the graphene powder is prepared by supercritical carbon dioxide exfoliation.

[0007] The mixed slurry is subjected to hydrolysis to obtain a hydrolyzed solution;

[0008] The hydrolyzed solution is subjected to a hydrothermal reaction to recover the solid product.

[0009] Optionally, the graphene powder has a D50 particle size of 0.5–5 μm, a sheet diameter of 1–10000 nm, fewer than 10 layers, and a specific surface area of ​​100–800 m². 2 / g.

[0010] Optionally, the graphene powder has a D50 particle size of 1–2.5 μm, a sheet diameter of 10–5000 nm, fewer than 8 layers, and a specific surface area of ​​150–600 m². 2 / g.

[0011] Optionally, the silicon source is one or more selected from methyl silicate, ethyl silicate, propyl silicate, butyl silicate, methylsilane, ethylsilane, and propylsilane; and / or,

[0012] The titanium source is one or more selected from titanate, titanium tetrachloride, and titanium oxysulfate; and / or,

[0013] The organic template agent is selected from one or more of urea, quaternary ammonium bases, fatty amines, and alcohol amines.

[0014] Optionally, the molar ratio of the silicon source (calculated as SiO2), the titanium source (calculated as TiO2), the graphene powder (calculated as carbon), the organic template agent (calculated as nitrogen), and water is 100:(0.5-5):(0.2-10):(10-50):(800-5000).

[0015] Optionally, the mixing conditions include: a temperature of 20–80°C and a time of 0.1–8 h; and / or,

[0016] The conditions for the hydrolysis treatment include: a temperature of 70–100°C and a time of 3–24 hours; and / or,

[0017] The conditions for the hydrothermal reaction include: being carried out under autogenous pressure, at a temperature of 110–200°C, and for a time of 6–96 hours.

[0018] Optionally, the method further includes a step of calcining the solid product; wherein the calcination conditions include a temperature of 400–800°C and a time of 1–12 h.

[0019] A second aspect of this disclosure provides a catalyst prepared by the method described in the first aspect of this disclosure.

[0020] In a third aspect, this disclosure provides a method for catalytic epoxidation of cyclododecanetriene, the method comprising: contacting cyclododecanetriene, an oxidant, a solvent and a catalyst to carry out an oxidation reaction, wherein the catalyst is the catalyst described in the second aspect of this disclosure.

[0021] Optionally, the oxidant is one or more selected from hydrogen peroxide, tert-butyl hydroperoxide, phenethyl hydroperoxide, isopropylphenyl hydroperoxide, cyclohexyl hydroperoxide, peracetic acid, and peroxypropionic acid; and / or,

[0022] The solvent is one or more selected from acetone, methanol, isopropanol, tert-butanol, ethanol, acetonitrile, acetic acid, and ethyl acetate; and / or,

[0023] The weight ratio of the catalyst, the solvent, the cyclododecanetriene, and the oxidant is 1:(2-100):(0.5-20):(0.2-20); and / or,

[0024] The conditions for the oxidation reaction include: a temperature of 20–100°C and a time of 1–12 h.

[0025] Through the above technical solution, this disclosure adds graphene powder to the raw materials for catalyst preparation, so that the resulting catalyst has suitable ordered mesopores and macropores, which effectively improves the accessibility and diffusion performance of the catalyst's reactive centers. Using this catalyst in the epoxidation reaction of macrocyclic olefins is beneficial to obtaining significantly improved catalytic activity and activity stability, as well as selectivity for the target product.

[0026] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0027] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0028] In a first aspect, this disclosure provides a method for preparing a catalyst, the method comprising the following steps:

[0029] A silicon source, a titanium source, an organic template agent, graphene powder, and water are mixed to obtain a mixed slurry; wherein the graphene powder is prepared by supercritical carbon dioxide exfoliation.

[0030] The mixed slurry is subjected to hydrolysis to obtain a hydrolyzed solution;

[0031] The hydrolyzed solution is subjected to a hydrothermal reaction to recover the solid product.

[0032] The method disclosed herein adds graphene powder to the raw materials for preparing titanium-silicon catalysts, thereby enabling the prepared catalysts to possess suitable ordered mesopores and macropores, effectively improving the accessibility of the catalyst's reactive centers. At the same time, the addition of graphene powder can promote the effective dispersion of titanium species and enhance their binding with silicon species, thereby more specifically improving the diffusion rate of materials in the catalytic reaction, further enhancing the catalyst's reactivity, activity stability, and selectivity for the target product.

[0033] The graphene powder is prepared by supercritical carbon dioxide exfoliation. Graphene powder prepared by supercritical carbon dioxide exfoliation has a more uniform particle size distribution and fewer layers, which is beneficial to improving the reaction activity, activity stability, and selectivity of the catalyst for the target product. For example, the preparation steps of the graphene powder may include: adding graphite to a reaction vessel, sealing the reaction vessel, introducing a gaseous intercalation medium (i.e., carbon dioxide) into the reaction vessel, and controlling the pressure inside the reaction vessel at 1–200 atm by adjusting the gas flow rate of the gaseous intercalation medium. Under this pressure and stirring conditions, the system temperature is raised to 25–500°C to carry out the molecular intercalation reaction for 1–24 hours. After the reaction is completed, rapid depressurization is performed to rapidly reduce the pressure inside the reaction vessel to half or less within 0.1 seconds. Then, the gas is released to atmospheric pressure, the buffer tank is opened, and the graphene powder is obtained.

[0034] In one specific embodiment, the D50 particle size of the graphene powder can be 0.5–5 μm, preferably 1–2.5 μm; its sheet diameter can be 1–10000 nm, preferably 10–5000 nm; the number of layers can be less than 10, preferably less than 8; and the specific surface area can be 100–800 m². 2 / g, preferably 150-600m 2 / g.

[0035] According to this disclosure, the silicon source can be an organosilicon source and / or an inorganic silicon source; specifically, the silicon source can be one or more selected from methyl silicate, ethyl silicate, propyl silicate, butyl silicate, methylsilane, ethylsilane and propylsilane.

[0036] The titanium source can be a titanium-containing compound. Specifically, the titanium source can be one or more selected from titanate, titanium tetrachloride and titanium oxysulfate, preferably one or more selected from tetrabutyl titanate, tetraisopropyl titanate and titanium oxysulfate.

[0037] The organic template agent may be one or more selected from urea, quaternary ammonium bases, aliphatic amines, and alkanolamines; wherein the quaternary ammonium base may be one or more selected from tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide; the aliphatic amine may be one or more selected from ethylamine, n-butylamine, butanediamine, and hexamethylenediamine; and the alkanolamine may be one or more selected from monoethanolamine, diethanolamine, and triethanolamine.

[0038] The proportions of each raw material can be adjusted within a certain range. In one specific embodiment, the molar ratio of the silicon source (calculated as SiO2), the titanium source (calculated as TiO2), the graphene powder (calculated as carbon), the organic template agent (calculated as nitrogen), and water can be 100:(0.5-5):(0.2-10):(10-50):(800-5000), preferably 100:(1-3):(1-10):(10-25):(1000-2500).

[0039] The mixed slurry is obtained by mixing the raw materials. The mixing conditions may include: a temperature of 20-80°C, preferably 30-50°C; and a time of 0.1-8 hours, preferably 0.5-3 hours.

[0040] To achieve a favorable mixing effect and further enhance the catalytic activity of the catalyst, in a preferred embodiment, the step of mixing the silicon source, titanium source, organic template agent, graphene powder, and water includes:

[0041] The silicon source and the titanium source were first mixed at 20–60°C and a stirring speed of 10–2000 rpm for 0.1–2 hours to obtain the first material;

[0042] The organic template agent, graphene powder, and water are mixed for 0.5 to 3 hours at 20–60°C and a stirring speed of 100–2000 rpm to obtain the second material.

[0043] The first material and the second material are mixed for 1 to 3 hours at 20 to 80°C and a stirring speed of 100 to 2000 rpm to obtain the mixed slurry.

[0044] According to this disclosure, the conditions for the hydrolysis treatment may include: a temperature of 70–100°C, preferably 75–95°C, and a time of 3–24 h, preferably 6–12 h. To achieve a favorable hydrolysis treatment effect and further enhance the catalytic activity of the catalyst, in a preferred embodiment, the temperature of the hydrolysis treatment is 5–70°C higher than the temperature of the mixing (including at least one of the first, second, and third mixtures described above), more preferably 15–55°C higher.

[0045] The conditions for the hydrothermal reaction may include: being carried out under autogenous pressure, at a temperature of 110–200°C, preferably 130–180°C; and a reaction time of 6–96 h, preferably 12–72 h. The material after the hydrothermal reaction is subjected to the required solid-liquid separation to recover the solid phase product.

[0046] Furthermore, the method may also include a step of calcining the solid product; wherein the calcination conditions may include: a temperature of 400–800°C, preferably 500–700°C; and a time of 1–12 h, preferably 2–6 h.

[0047] A second aspect of this disclosure provides a catalyst prepared according to the method described in the first aspect of this disclosure. The catalyst has a mesoporous-macroporous hierarchical porous structure.

[0048] In one specific embodiment, the molar ratio of titanium, silicon, and carbon in the catalyst is (0.5–5):100:(0.1–5), preferably (1–4):100:(0.2–2). Further, the BET specific surface area of ​​the catalyst can be 300–800 cm². 2 / g, preferably 400-600cm 2 / g; total pore volume can be 0.5–2.0 cm³. 3 / g, preferably 0.8~1.6cm 2 / g; the ratio of mesopore volume to total pore volume can be (0.6~1):1, preferably (0.7~0.9):1.

[0049] The catalyst disclosed herein exhibits high accessibility of its reactive active center, good catalytic activity and activity stability, and demonstrates high conversion rate and target product selectivity in catalytic oxidation reactions of cyclic macromolecules such as macrocyclic olefins.

[0050] In a third aspect, this disclosure provides a cyclododecanetriene (chemical formula C...) 12 H 18 A method for catalytic epoxidation (CAS No. 16988-38-6), comprising: contacting a cyclododecanetriene, an oxidant, a solvent and a catalyst to carry out an oxidation reaction, wherein the catalyst is the catalyst described in the second aspect of this disclosure.

[0051] The oxidant may be one or more selected from hydrogen peroxide, tert-butyl hydrogen peroxide, phenethyl hydrogen peroxide, isopropylphenyl hydrogen peroxide, cyclohexyl hydrogen peroxide, peracetic acid, and perpropionic acid, preferably hydrogen peroxide; the oxidant may be in the form of an aqueous solution, and its concentration may be, for example, 10-40% by weight. The solvent may be one or more selected from acetone, methanol, isopropanol, tert-butanol, ethanol, acetonitrile, acetic acid, and ethyl acetate.

[0052] The weight ratio of the catalyst, the solvent, the cyclododecanetriene, and the oxidant can be 1:(2-100):(0.5-20):(0.2-20), preferably 1:(5-50):(1-10):(0.5-10).

[0053] The conditions for the oxidation reaction may include: a temperature of 20–100°C, preferably 30–80°C; a pressure of 0–1 MPa, preferably 0–0.5 MPa; and a time of 1–12 h, preferably 2–6 h.

[0054] The method disclosed herein can effectively improve the feed conversion rate and the selectivity of the target monoepoxide product, wherein the monoepoxide product is 1,2-epoxy-5,9-cyclododecadiene (chemical formula C). 12 H 18 Specifically, the raw material conversion rate can reach over 20%, and the selectivity for 1,2-epoxy-5,9-cyclododecadiene can reach over 80%.

[0055] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0056] In the examples, the BET specific surface area, mesopore volume, and total pore volume of the catalyst were tested using the low-temperature N2 adsorption-desorption method.

[0057] Example 1

[0058] (1) Add 1g of graphite to the reactor, introduce gaseous intercalation medium (carbon dioxide) into the reactor, and control the pressure inside the reactor at 1 atm by adjusting the gas flow rate of the gaseous intercalation medium. Under the conditions of this pressure and stirring speed of 200 rpm, raise the system temperature to 200℃ to carry out the molecular intercalation reaction. After reacting for 0.5h, rapidly depressurize to reduce the pressure inside the reactor to half or less within 0.1s. Then release the gas to atmospheric pressure, open the buffer tank, and obtain 0.9g of graphene powder. The graphene powder has a D50 particle size of 1.8μm, a sheet diameter of 870~1880nm, a number of layers of 3~8, and a specific surface area of ​​221m². 2 / g.

[0059] (2) Ethyl silicate and tetrabutyl titanate were stirred and mixed at 30°C for 0.5 h at a stirring speed of 600 rpm to obtain the first material; the above graphene powder was stirred and mixed with tetrapropylammonium hydroxide aqueous solution (25% by weight) at 35°C for 2 h at a stirring speed of 300 rpm to obtain the second material; the first material and the second material were mixed and stirred at 75°C for 2 h at a stirring speed of 500 rpm to obtain a mixed slurry. The molar ratio of ethyl silicate (as SiO2), tetrabutyl titanate (as TiO2), graphene powder (as C), tetrapropylammonium hydroxide (as N) and water was 100:3:1:25:2500.

[0060] (3) The above mixed slurry was hydrolyzed at 80°C for 6 hours to obtain a hydrolyzed solution.

[0061] (4) The above hydrolysis solution was transferred to a sealed high-pressure reactor and subjected to hydrothermal reaction at 170°C and autogenous pressure for 48 hours. The solid product was recovered, filtered, washed, and naturally dried. Then it was calcined at 500°C for 3 hours to obtain the catalyst prepared in this embodiment. The molar ratio of titanium, silicon and carbon in the catalyst was 2.6:100:0.3. Data such as BET specific surface area are listed in Table 1.

[0062] Example 2

[0063] The catalyst was prepared according to the method of Example 1, except that in step (2), the molar ratio of tetrabutyl silicate (as SiO2), tetrabutyl titanate (as TiO2), graphene powder (as C), tetrapropylammonium hydroxide (as N) and water was 100:5:0.2:30:5000; and in step (3), the mixed slurry was hydrolyzed at 70°C for 12 h. The molar ratio of titanium, silicon and carbon in the catalyst prepared in this example was 4.1:100:0.1, and the BET specific surface area and other data are listed in Table 1.

[0064] Example 3

[0065] The catalyst was prepared according to the method of Example 1, except that the graphene powder prepared in step (1) had a D50 particle size of 0.5 μm, a sheet diameter of 560–2900 nm, 3–6 layers, and a specific surface area of ​​310 m². 2 / g. The molar ratio of titanium, silicon and carbon in the catalyst prepared in this example is 2.7:100:0.9, and the BET specific surface area and other data are listed in Table 1.

[0066] Example 4

[0067] The catalyst was prepared using the method of Example 1, the only difference being that the graphene powder prepared in step (1) had a D50 particle size of 5 μm, a sheet diameter of 2500–7000 nm, 6–10 layers, and a specific surface area of ​​115 m². 2 / g. The molar ratio of titanium, silicon and carbon in the catalyst prepared in this embodiment is 2.1:100:0.1, and the BET specific surface area and other data are listed in Table 1.

[0068] Comparative Example 1

[0069] The catalyst was prepared according to the method of Example 1, except that graphene powder was not added in step (2). The molar ratio of titanium to silicon in the catalyst prepared in this comparative example was 2.5:100, and the BET specific surface area and other data are listed in Table 1.

[0070] Comparative Example 2

[0071] The catalyst was prepared according to the method in Example 1, except that the graphene powder used in this comparative example was prepared by redox method (purchased from Changzhou Sixth Element Materials Technology Co., Ltd., trade number SE1233, D50 particle size 2.6 μm, sheet diameter 2100–4300 nm, number of layers 2–6, specific surface area 242 m²). 2 / g). The molar ratio of titanium, silicon and carbon in the catalyst prepared in this comparative example is 2.2:100:0.5, and the BET specific surface area and other data are listed in Table 1.

[0072] Comparative Example 3

[0073] The catalyst was prepared according to the method in Example 1, except that the graphene powder used in this comparative example was prepared by solid-phase intercalation exfoliation (purchased from Deyang Xitan Technology Co., Ltd., trade number HE-01, D50 particle size 2μm, sheet diameter 1500-3000nm, number of layers 2-10, specific surface area 124m²). 2 / g). The molar ratio of titanium, silicon and carbon in the catalyst prepared in this comparative example is 2.0:100:0.1, and the BET specific surface area and other data are listed in Table 1.

[0074] Table 1

[0075] <![CDATA[BET specific surface area, cm 2 / g]]> <![CDATA[Total pore volume, cm 2 / g]]> Mesopore volume / Total pore volume Example 1 452 1.352 0.847 Example 2 389 0.748 0.663 Example 3 375 0.953 0.616 Example 4 358 1.697 0.901 Comparative Example 1 420 0.296 0.224 Comparative Example 2 373 1.752 0.913 Comparative Example 3 391 0.478 0.397

[0076] Test Implementation Examples

[0077] The catalysts prepared in the examples and comparative examples were used for the catalytic epoxidation reaction of cyclododecanetrienes, and the specific steps are as follows:

[0078] The catalyst, acetone, cyclododecanetriene, and hydrogen peroxide aqueous solution (H2O2 content 30 wt%) were sealed in a high-pressure reactor at a weight ratio of catalyst:acetone:cyclododecanetriene:hydrogen peroxide aqueous solution = 1:30:8:5 and reacted at 60°C for 3 h. The product concentration was determined by an Agilent 6890N gas chromatograph using a capillary column (30 m × 0.25 mm) HP-1. The conversion rate of cyclododecanetriene and the selectivity of the monoepoxide product were calculated according to the following formula, where the monoepoxide product was 1,2-epoxy-5,9-cyclododecanediene. The results are shown in Table 2.

[0079] Cyclododecanetriene conversion rate = (Weight of input cyclododecanetriene – Weight of remaining cyclododecanetriene after reaction) / Weight of input cyclododecanetriene × 100%

[0080] Monoepoxide product selectivity = (molar amount of monoepoxide product in the product) / (weight of cyclododecanetriene added – weight of cyclododecanetriene remaining after reaction) × 100%

[0081] Table 2

[0082] Cyclododecanetriene conversion rate / % Monocyclic oxidation product selectivity / % Example 1 36.2 88 Example 2 28.5 86 Example 3 25.3 82 Example 4 20.0 85 Comparative Example 1 0.1 30 Comparative Example 2 6.5 49 Comparative Example 3 7.2 46

[0083] As shown in Table 2, the catalyst provided in this disclosure has higher feed conversion rate and target product selectivity for the epoxidation reaction of cyclododecanetriene.

[0084] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0085] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0086] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for preparing a catalyst, characterized in that, The method includes: A silicon source, a titanium source, an organic template agent, graphene powder, and water are mixed to obtain a mixed slurry; wherein the graphene powder is prepared by supercritical carbon dioxide exfoliation. The mixed slurry is subjected to hydrolysis to obtain a hydrolyzed solution; The hydrolyzed solution is subjected to a hydrothermal reaction to recover the solid product.

2. The method according to claim 1, wherein, The graphene powder has a D50 particle size of 0.5–5 μm, a sheet diameter of 1–10000 nm, fewer than 10 layers, and a specific surface area of ​​100–800 m². 2 / g.

3. The method according to claim 2, wherein, The graphene powder has a D50 particle size of 1–2.5 μm, a sheet diameter of 10–5000 nm, fewer than 8 layers, and a specific surface area of ​​150–600 m². 2 / g.

4. The method according to claim 1, wherein, The silicon source is one or more selected from methyl silicate, ethyl silicate, propyl silicate, butyl silicate, methylsilane, ethylsilane, and propylsilane; and / or, The titanium source is one or more selected from titanate, titanium tetrachloride, and titanium oxysulfate; and / or, The organic template agent is selected from one or more of urea, quaternary ammonium bases, fatty amines, and alcohol amines.

5. The method according to claim 1, wherein, The molar ratio of the silicon source (calculated as SiO2), the titanium source (calculated as TiO2), the graphene powder (calculated as carbon), the organic template agent (calculated as nitrogen), and water is 100:(0.5-5):(0.2-10):(10-50):(800-5000).

6. The method according to claim 1, wherein, The mixing conditions include: a temperature of 20–80°C and a time of 0.1–8 hours; and / or, The conditions for the hydrolysis treatment include: a temperature of 70–100°C and a time of 3–24 hours; and / or, The conditions for the hydrothermal reaction include: being carried out under autogenous pressure, at a temperature of 110–200°C, and for a time of 6–96 hours.

7. The method according to claim 1, wherein, The method further includes a step of calcining the solid product; wherein the calcination conditions include a temperature of 400–800°C and a time of 1–12 h.

8. The catalyst prepared by the method according to any one of claims 1 to 7.

9. A method for catalytic epoxidation of cyclododecanetriene, characterized in that, The method includes: contacting cyclododecanetriene, an oxidant, a solvent, and a catalyst to carry out an oxidation reaction, wherein the catalyst is the catalyst according to claim 8.

10. The method according to claim 9, wherein, The oxidant is one or more selected from hydrogen peroxide, tert-butyl hydroperoxide, phenethyl hydroperoxide, isopropylphenyl hydroperoxide, cyclohexyl hydroperoxide, peracetic acid, and peroxypropionic acid; and / or, The solvent is one or more selected from acetone, methanol, isopropanol, tert-butanol, ethanol, acetonitrile, acetic acid, and ethyl acetate; and / or, The weight ratio of the catalyst, the solvent, the cyclododecanetriene, and the oxidant is 1:(2-100):(0.5-20):(0.2-20); And / or, The conditions for the oxidation reaction include: a temperature of 20–100°C and a time of 1–12 h.