Preparation method of hierarchical titanium-silicate molecular sieve containing framework manganese and its application in the preparation of adipic acid

Abstract

The present invention discloses a preparation method of a hierarchical titanium silicalite containing framework manganese and its application in the preparation of adipic acid, relating to the technical field of hierarchical zeolite materials and catalysts; the preparation method includes the following steps: adding IPA and deionized water dropwise to TEOS, adding tetrapropylammonium hydroxide dropwise, and stirring until complete hydrolysis to obtain a hydrolysis solution; preparing an aqueous solution of titanium trichloride and an aqueous solution of manganese acetate tetrahydrate; dropping them into the hydrolysis solution and stirring to obtain a colloid; then heating the colloid for hydrolysis, aging overnight at room temperature to obtain an aging solution; adding a mesoporous template agent to the aging solution for further hydrolysis, transferring it to a hydrothermal autoclave for crystallization, and after filtration, washing, drying and calcination, a hierarchical titanium silicalite containing framework manganese is obtained. The present invention adopts one-step hydrothermal synthesis, and the molecular sieve can catalytically activate molecular oxygen to realize one-step green oxidation for the preparation of adipic acid, simplifying the process flow, reducing energy consumption, reducing three wastes, and avoiding the problem of equipment corrosion.

Description

Technical Field

[0001] The present invention relates to the technical field of hierarchical zeolite materials and catalysts, and particularly relates to a preparation method of a hierarchical titanium silicalite molecular sieve containing framework manganese and its application in the preparation of adipic acid. Background Art

[0002] Adipic acid is an important bulk chemical for the production of nylon-66 resin, food additives, plasticizers, and pharmaceutical synthesis. Currently, the global production capacity of adipic acid has reached 3.74 million tons / year and shows an increasing trend year by year, with an annual growth rate of more than 3.36%. At present, there are mainly three processes for the industrial preparation of adipic acid: cyclohexane oxidation method, cyclohexene hydration method, and phenol hydrogenation reduction method. Among them, the production of AA by the two-step oxidation of cyclohexane is the most widely used method. Specifically, cyclohexane is first oxidized to KA oil in air, and then KA oil is oxidized with nitric acid to obtain an adipic acid selectivity of more than 90% ( Figure 1 )

[0003] However, the two-step oxidation method of cyclohexane still has the following deficiencies: 1. The single-pass conversion rate of the air oxidation of cyclohexane is low (3%-4%); 2. The process is divided into two steps, and the process flow is complex; 3. The use of high-concentration nitric acid in the second step leads to high energy consumption and serious equipment corrosion problems; 4. The toxic nitrogen oxides generated during the reaction cause serious environmental pollution and greenhouse effect. Therefore, in order to achieve the goal of "green chemistry", it is of great industrial application significance to design excellent catalysts and develop a new preparation process to directly oxidize cyclohexane to AA using molecular oxygen, hydrogen peroxide, and other green oxidants.

[0004] To solve this problem, many processes have been proposed to produce adipic acid by one-step oxidation of cyclohexane using green oxidants. Yasutaka Ishii et al. developed a solvent-free cyclohexane oxidation process using N-hydroxyphthalimide (NHPI), Mn(acac)2, and Co(OAc)2 as catalysts and molecular oxygen as the oxidant. The reaction was carried out at 100 °C for 20 h to directly oxidize cyclohexane to adipic acid, achieving a cyclohexane conversion of 73% and an adipic acid selectivity of 73%. Zhong Wenzhou et al. further improved this method and prepared adipic acid by one-step oxidation of cyclohexane catalyzed by N-hydroxyphthalimide (NHPI) under the conditions of no cocatalyst and no metal, obtaining a cyclohexane conversion of 27% and an adipic acid selectivity of 79%. However, the NHPI-catalyzed oxidation is a homogeneous reaction, which has problems such as difficult separation and long process flow. The research also found that metal porphyrins can catalyze the oxidation of cyclohexane to prepare adipic acid through a green route. Patent CN105884598A uses heme, a catalyst with a single-metal porphyrin structure, and can obtain a product selectivity of more than 90%. In addition, patents CN1247501C and CN1405131A both disclose the use of metal porphyrins as catalysts to catalyze the oxidation of cyclohexane to adipic acid, but the synthesis of metal porphyrin catalysts is difficult, costly, and the reaction time is relatively long, still requiring further improvement.

[0005] There are also some catalysts such as: Patent CN110872224A discloses acid-modified sepiolite, Patent CN109095493A discloses two-dimensional ultrathin CuO@SAPO-34 zeolite materials, Patent CN115301228A discloses multi-metal quasicrystal alloy catalysts, Patent CN113559925A discloses heteropolyacid catalysts with multi-metal centers, and Patent CN115608370A discloses bimetallic hydroxide catalysts. However, these catalysts have problems such as complex preparation processes, poor solvent tolerance, low cyclohexane conversion, and low adipic acid yield. Summary of the Invention

[0006] To solve the above technical problems, the purpose of the present invention is to provide a preparation method of a hierarchical titanium silicalite containing framework manganese and its application in the preparation of adipic acid. By one-step hydrothermal synthesis, the obtained catalyst can catalytically activate molecular oxygen to achieve one-step green oxidation for preparing adipic acid, simplify the process flow, reduce energy consumption, reduce three wastes, and avoid equipment corrosion problems.

[0007] The technical solution of the present invention to solve the above technical problems is as follows: Provide a preparation method of a hierarchical titanium silicalite containing framework manganese, including the following steps:

[0008] (1) Isopropanol (IPA, 99 wt%) and deionized water were added dropwise to tetraethyl orthosilicate (TEOS), and then tetrapropylammonium hydroxide was added dropwise. The mixture was stirred until tetraethyl orthosilicate was completely hydrolyzed to obtain a hydrolysis solution;

[0009] (2) 0.5 mL of titanium trichloride (20 wt%) was diluted in 2 mL of water to obtain an aqueous titanium trichloride solution; 0 - 0.624 g of manganese acetate tetrahydrate was dissolved in 10 g of water to obtain an aqueous manganese acetate tetrahydrate solution; The aqueous titanium trichloride solution and the aqueous manganese acetate tetrahydrate solution were added dropwise to the hydrolysis solution obtained in step (1), and stirred to obtain a colloidal substance;

[0010] (3) The colloidal substance obtained in step (2) was hydrolyzed at 55 °C for 1 h, then the temperature was raised to 85 °C and hydrolysis continued for 8 h, and then aged overnight at room temperature to obtain an aged solution;

[0011] (4) A mesoporous template agent was added to the aged solution obtained in step (3), and hydrolysis was carried out at 80 °C for 6 h, then transferred to a hydrothermal autoclave lined with Teflon, and crystallized at 175 °C for 3 d. After filtration, washing and drying, it was calcined at a rate of 2 °C / min to 550 °C for 6 h to obtain a hierarchical titanium silicalite molecular sieve containing framework manganese.

[0012] Furthermore, in step (1), the mass ratio of tetraethyl orthosilicate, isopropanol, deionized water and tetrapropylammonium hydroxide is 8 - 10 g: 3 - 5 g: 3 - 5 g: 15 - 17 g.

[0013] Furthermore, in step (1), the mass ratio of tetraethyl orthosilicate, isopropanol, deionized water and tetrapropylammonium hydroxide is 9.1 g: 4 g: 4 g: 16 g.

[0014] Furthermore, in step (3), in the aged solution, the molar ratio of SiO2, TiO2, MnO2, TPAOH, H2O is 1:0.015:0 - 0.06:0.36:27.

[0015] Furthermore, in step (4), the mesoporous template agent is phenylaminopropyltrimethoxysilane.

[0016] Furthermore, in step (4), drying is carried out at 80 °C.

[0017] The present invention also provides a hierarchical titanium silicalite molecular sieve containing framework manganese prepared by the preparation method of the above hierarchical titanium silicalite molecular sieve containing framework manganese.

[0018] This hierarchical titanium silicalite molecular sieve containing framework manganese is named HMTS - x (x = 0, 1, 2, 3, 4), where x represents the molar ratio of Mn to Ti species.

[0019] The strategy of the present invention enables multiple metal ions to enter the zeolite framework simultaneously and selectively, and this strategy is simple to operate. By using phenylaminopropyltrimethoxysilane as a mesoporous agent, the connection of coalesced MFI small units can be promoted by forming Si-O-Si covalent bonds with free metal ions and binding them to the framework. This method effectively promotes the formation of a hierarchical structure and avoids the formation of anatase TiO2, which is inferred from the characterization of solid ultraviolet and infrared spectroscopy ( Figure 2 ).

[0020] The present invention also provides the application of the above-mentioned hierarchical titanium-silicon molecular sieve containing framework manganese in the preparation of adipic acid by oxidizing cyclohexane.

[0021] A method for preparing adipic acid by oxidizing cyclohexane, comprising the following steps:

[0022] React cyclohexane, a solvent, and a hierarchical titanium-silicon molecular sieve containing framework manganese as a catalyst at 120-150 °C and an oxygen pressure of 1-2.5 MPa for 2-12 h to obtain adipic acid.

[0023] Furthermore, the mass ratio of cyclohexane to the solvent is 1:8-1:10; the mass ratio of the hierarchical titanium-silicon molecular sieve containing framework manganese to cyclohexane is 1:40-1:60.

[0024] The present invention has the following beneficial effects:

[0025] 1. The strategy of the present invention can simultaneously incorporate manganese and titanium into the framework of the hierarchical zeolite and avoid the formation of anatase TiO2, obtaining a multifunctional hierarchical manganese-containing titanium-silicon molecular sieve zeolite; the addition of framework manganese enhances the surface acidity and oxygen vacancy concentration of the catalyst, contributing to the activation of oxygen. Framework titanium species are beneficial for activating the C-H of cyclohexane, and the two exhibit good synergistic effects; under relatively mild conditions, HMTS can efficiently oxidize cyclohexane to adipic acid in one pot, achieving high cyclohexane conversion and adipic acid selectivity. The process is simple, the operation is convenient, the reaction energy consumption is low, and the catalyst cost is low, having very good industrial application prospects.

[0026] 2. The titanium and manganese species of the catalyst coexist in the framework and do not induce the massive formation of anatase TiO2 and surface-aggregated MnOx. The introduction of framework manganese not only increases the surface oxygen vacancies but also generates stronger surface acidity through interaction with the hierarchical TS-1 zeolite. During the preparation of the catalyst, we adopted the strategy of simultaneously adding active species and re-coordination. Manganese acetate dihydrate was used as the manganese source, and the coordination and calcination oxidation resulted in more framework manganese, which was highly dispersed in the framework. The catalyst prepared by the above method has the advantages of stable structure, low price, strong anti-sintering property, and good recyclability. It shows excellent cyclohexane conversion in the catalyst activity test. The present invention has the advantages of high adipic acid selectivity and green process. Description of the Drawings

[0027] Figure 1 It is a comparison diagram of the method for preparing adipic acid by oxidizing cyclohexane in the present invention and the commonly used industrial process;

[0028] Figure 2 It is the solid UV and IR characterization diagrams of the catalyst prepared in the present invention. Detailed Embodiments

[0029] The principles and features of the present invention are described below. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. For those not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are adopted. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase. Examples

[0030] A hierarchical titanium-silicon molecular sieve containing framework manganese, and its preparation method includes the following steps:

[0031] (1) 4 g of isopropyl alcohol (IPA, 99 wt%) and 4 g of deionized water were added dropwise to 9.1 g of tetraethyl orthosilicate (TEOS), and then 16 g of tetrapropylammonium hydroxide was added dropwise, and stirred until the tetraethyl orthosilicate was completely hydrolyzed to obtain a hydrolysis solution;

[0032] (2) 0.5 mL of titanium trichloride (20 wt%) was diluted in 2 mL of water to obtain an aqueous solution of titanium trichloride; 0 - 0.624 g of manganese acetate tetrahydrate was dissolved in 10 g of water to obtain an aqueous solution of manganese acetate tetrahydrate; the aqueous solution of titanium trichloride and the aqueous solution of manganese acetate tetrahydrate were added dropwise to the hydrolysis solution obtained in step (1), and stirred to obtain a colloid;

[0033] (3) Hydrolyze the colloidal substance obtained in step (2) at 55 °C for 1 h, then raise the temperature to 85 °C and continue hydrolysis for 8 h, and then age overnight at room temperature to obtain an aging solution; the molar ratio of SiO2, TiO2, MnO2, TPAOH, and H2O is 1:0.015:0 - 0.06:0.36:27;

[0034] (4) Add a mesoporous template agent (phenylaminopropyltrimethoxysilane) to the aging solution obtained in step (3), hydrolyze at 80 °C for 6 h, then transfer it to a hydrothermal autoclave with a Teflon lining, crystallize at 175 °C for 3 d, filter, wash, dry at 80 °C, and calcine at a rate of 2 °C / min to 550 °C for 6 h to obtain a hierarchical titanium silicalite molecular sieve containing framework manganese.

[0035] The obtained hierarchical titanium silicalite molecular sieve containing framework manganese is named HMTS-x (x = 0, 1, 2, 3, 4), where x represents the molar ratio of Mn to Ti species. Example

[0036] A method for preparing adipic acid by oxidizing cyclohexane, comprising the following steps:

[0037] React 2.4 g of cyclohexane, 21 g of a solvent (acetonitrile), and 0.05 g of a hierarchical titanium silicalite molecular sieve containing framework manganese (HMTS-1) as a catalyst at 140 °C and an oxygen pressure of 2 MPa for 6 h to obtain adipic acid.

[0038] The conversion rate of cyclohexane is 58.3%, and the selectivity of adipic acid is 54.7%. Example

[0039] A method for preparing adipic acid by oxidizing cyclohexane, comprising the following steps:

[0040] React 2.4 g of cyclohexane, 21 g of a solvent (acetonitrile), and 0.05 g of a hierarchical titanium silicalite molecular sieve containing framework manganese (HMTS-2) as a catalyst at 140 °C and an oxygen pressure of 2 MPa for 6 h to obtain adipic acid.

[0041] The conversion rate of cyclohexane is 74.4%, and the selectivity of adipic acid is 62.2%. Example

[0042] A method for preparing adipic acid by oxidizing cyclohexane, comprising the following steps:

[0043] React 2.4 g of cyclohexane, 21 g of a solvent (acetonitrile), and 0.05 g of a hierarchical titanium silicalite molecular sieve containing framework manganese (HMTS-3) as a catalyst at 140 °C and an oxygen pressure of 2 MPa for 6 h to obtain adipic acid.

[0044] The conversion rate of cyclohexane is 81.6%, and the selectivity of adipic acid is 71.5%. Example

[0045] A method for preparing adipic acid by oxidizing cyclohexane, comprising the following steps:

[0046] React 2.4 g of cyclohexane, 21 g of a solvent (acetonitrile), and 0.05 g of a hierarchical titanium silicalite containing framework manganese (HMTS-4) as a catalyst at 140 °C and an oxygen pressure of 2 MPa for 6 h to obtain adipic acid.

[0047] The conversion rate of cyclohexane is 79.1%, and the selectivity of adipic acid is 68.3%. Example

[0048] A method for preparing adipic acid by oxidizing cyclohexane, comprising the following steps:

[0049] React 2.4 g of cyclohexane, 21 g of a solvent (acetonitrile), and 0.05 g of a hierarchical titanium silicalite containing framework manganese (HTS-1) as a catalyst at 140 °C and an oxygen pressure of 2 MPa for 6 h to obtain adipic acid.

[0050] The conversion rate of cyclohexane is 43.4%, and the selectivity of adipic acid is 41.1%. Example

[0051] A method for preparing adipic acid by oxidizing cyclohexane, comprising the following steps:

[0052] React 2.4 g of cyclohexane, 21 g of a solvent (acetone), and 0.05 g of a hierarchical titanium silicalite containing framework manganese (HMTS-3) as a catalyst at 140 °C and an oxygen pressure of 2 MPa for 6 h to obtain adipic acid.

[0053] The conversion rate of cyclohexane is 61.6%, and the selectivity of adipic acid is 56.4%. Example

[0054] A method for preparing adipic acid by oxidizing cyclohexane, comprising the following steps:

[0055] React 10 g of cyclohexane and 0.2 g of a hierarchical titanium silicalite containing framework manganese (HMTS-3) as a catalyst at 140 °C and an oxygen pressure of 2 MPa for 6 h to obtain adipic acid.

[0056] The conversion rate of cyclohexane is 28.5%, and the selectivity of adipic acid is 58.1%. Example

[0057] A method for preparing adipic acid by oxidizing cyclohexane, comprising the following steps:

[0058] React 2.4 g of cyclohexane, 21 g of a solvent (acetonitrile), and 0.05 g of a hierarchical titanium silicalite molecular sieve containing framework manganese (HMTS-3) as a catalyst at 140 °C and an oxygen pressure of 2.5 MPa for 6 h to obtain adipic acid.

[0059] The conversion rate of cyclohexane is 83.4%, and the selectivity of adipic acid is 69.8%. Example

[0060] A method for preparing adipic acid by oxidizing cyclohexane, comprising the following steps:

[0061] React 2.4 g of cyclohexane, 21 g of a solvent (acetonitrile), and 0.05 g of a hierarchical titanium silicalite molecular sieve containing framework manganese (HMTS-3) as a catalyst at 135 °C and an oxygen pressure of 2 MPa for 6 h to obtain adipic acid.

[0062] The conversion rate of cyclohexane is 68.8%, and the selectivity of adipic acid is 58.2%. Example

[0063] A method for preparing adipic acid by oxidizing cyclohexane, comprising the following steps:

[0064] React 2.4 g of cyclohexane, 21 g of a solvent (acetonitrile), and 0.05 g of a hierarchical titanium silicalite molecular sieve containing framework manganese (HMTS-3) as a catalyst at 135 °C and an oxygen pressure of 2 MPa for 12 h to obtain adipic acid.

[0065] The conversion rate of cyclohexane is 86.5%, and the selectivity of adipic acid is 69.8%.

[0066] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a hierarchical titanium-silicate molecular sieve containing framework manganese, characterized in that It includes the following steps: (1) Drop isopropanol and deionized water into tetraethyl orthosilicate, and then drop tetrapropylammonium hydroxide, and stir until tetraethyl orthosilicate is completely hydrolyzed to obtain a hydrolysis solution; (2) Dilute 0.5 mL of titanium trichloride with a concentration of 20 wt% in 2 mL of water to obtain an aqueous solution of titanium trichloride; dissolve 0 - 0.624 g of manganese acetate tetrahydrate in 10 g of water to obtain an aqueous solution of manganese acetate tetrahydrate; drop the aqueous solution of titanium trichloride and the aqueous solution of manganese acetate tetrahydrate into the hydrolysis solution obtained in step (1), and stir to obtain a colloid; (3) Hydrolyze the colloid obtained in step (2) at 55 °C for 1 h, then raise the temperature to 85 °C and continue to hydrolyze for 8 h, and then age overnight at room temperature to obtain an aging solution; (4) Add a mesoporous template agent to the aging solution obtained in step (3), hydrolyze at 80 °C for 6 h, then transfer it to a hydrothermal kettle with a Teflon liner, crystallize at 175 °C for 3 d, filter, wash and dry, and calcine at a rate of 2 °C / min to 550 °C for 6 h to obtain a hierarchical titanium silicalite containing framework manganese; 2. The preparation method of the hierarchical titanium silicalite containing framework manganese as described in claim 1, characterized in that, In step (1), the mass ratio of tetraethyl orthosilicate, isopropanol, deionized water and tetrapropylammonium hydroxide is 8 - 10 g: 3 - 5 g: 3 - 5 g: 15 - 17 g.

3. The preparation method of the hierarchical titanium silicalite containing framework manganese according to claim 1 or 2, characterized in that, In step (1), the mass ratio of tetraethyl orthosilicate, isopropanol, deionized water and tetrapropylammonium hydroxide is 9.1 g: 4 g: 4 g: 16 g.

4. The preparation method of the hierarchical titanium silicalite containing framework manganese as described in claim 1, characterized in that, In step (3), in the aging solution, the molar ratio of SiO2, TiO2, MnO2, TPAOH, H2O is 1: 0.015: 0 - 0.06: 0.36:

27.

5. The preparation method of the hierarchical titanium silicalite containing framework manganese as described in claim 1, characterized in that, In step (4), the mesoporous template agent is phenylaminopropyltrimethoxysilane.

6. The preparation method of the hierarchical titanium silicalite containing framework manganese as described in claim 1, characterized in that, In step (4), dry at 80 °C.

7. The hierarchical titanium silicalite containing framework manganese prepared by the preparation method of the hierarchical titanium silicalite containing framework manganese according to any one of claims 1 - 5.

8. Use of the hierarchical titanium silicalite containing framework manganese according to claim 7 in the preparation of adipic acid by oxidizing cyclohexane.

9. A method for preparing adipic acid from cyclohexane oxide, characterized in that, It includes the following steps: React cyclohexane, a solvent and the hierarchical titanium silicalite containing framework manganese as a catalyst according to claim 7 at 120 - 150 °C and an oxygen pressure of 1 - 2.5 MPa for 2 - 12 h to obtain adipic acid.

10. The method for preparing adipic acid from cyclohexane oxide as claimed in claim 9, wherein, The mass ratio of cyclohexane to the solvent is 1: 8 - 1: 10; the mass ratio of the hierarchical titanium silicalite containing framework manganese to cyclohexane is 1: 40 - 1: 60.

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