A photocatalyst, a preparation method and application thereof
By loading noble metals and active metal photocatalysts onto titanium dioxide nanotubes, the problems of equipment corrosion and environmental pollution in the adipic acid synthesis process were solved, achieving efficient conversion of cyclohexane and good selectivity of adipic acid.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-18
- Publication Date
- 2026-06-19
AI Technical Summary
Existing technologies for the synthesis of adipic acid suffer from severe equipment corrosion, environmental pollution, and ecological damage, and the reaction conditions are dangerous and difficult to control.
A photocatalyst was prepared by supporting noble metals and active metals on titanium dioxide nanotubes for the oxidation of cyclohexane to adipic acid, avoiding the use of solvents and controlling the reaction temperature and pressure.
It achieves high cyclohexane conversion, good adipic acid selectivity, mild reaction conditions, reduced equipment corrosion and environmental pollution, and the catalyst can be reused.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photocatalyst synthesis technology. Specifically, it relates to a photocatalyst, its preparation method, and its application in the synthesis of adipic acid from cyclohexane. Background Technology
[0002] Adipic acid, also known as fatty acid, is an organic diacid with a wide range of applications. Its main use is in the condensation with hexamethylenediamine to produce Nylon-66 (polyhexamethylenediamine), and it can also be used in the production of polyurethane, polyols, biodegradable plastics, plasticizers, and acidulants. Currently, the cyclohexane air oxidation process is widely used industrially to produce adipic acid. Cyclohexane is oxidized in air to produce KA oil (a mixture of cyclohexanone and cyclohexanol), which is then oxidized with concentrated nitric acid to produce adipic acid. This process is rapid, with high conversion and yield, and is economically advantageous. However, this process consumes a large amount of nitric acid, with a concentrated nitric acid consumption of 1.3 t / t adipic acid. The use of concentrated nitric acid causes severe corrosion of equipment and releases large amounts of nitrogen oxides during production, causing environmental pollution and ecological damage. Furthermore, this process requires control of the cyclohexane conversion rate and the selectivity of the KA oil, resulting in low single-pass conversion rates. In recent years, a one-step direct oxidation method for cyclohexane to adipic acid has been extensively studied.
[0003] Patent CN200810030159.2 discloses a method for the direct production of adipic acid from cyclohexane via catalytic oxidation. This method involves mixing cyclohexane, a solvent, an initiator, and a carbon-based catalyst to form a mixed suspension. The suspension is then heated to 50-250°C, and oxygen or air is introduced as an oxidant. The pressure inside the reactor is maintained at 0.1-5 MPa, and the reaction is carried out for 0.1-20 hours. The resulting reaction mixture is then separated to obtain the adipic acid product. However, the high reaction temperature and high oxygen pressure pose a risk of explosion, and the need to add a solvent further complicates the subsequent product separation.
[0004] Patent CN201310512326.8 describes a catalyst for the direct oxidation of cyclohexane to adipic acid. The catalyst consists of a ferromagnetic ferrite metal catalyst and NHPI (N-hydroxyphthalimide) and NAPI (N-acetylphthalimide) radical catalysts. The reaction involves high oxygen pressure, posing a risk of explosion, and requires the addition of a solvent, which affects the separation of subsequent products.
[0005] This master's thesis focuses on the synthesis of titanium dioxide-based composite catalysts and their photocatalytic oxidation performance of cyclohexane. Bi₂O₃ and Bi₂O₃ / TiO₂ composite catalysts were prepared via a hydrothermal method for the photocatalytic oxidation of cyclohexane to cyclohexanol and cyclohexanone. However, the cyclohexane conversion rate was low, the synthesized products were cyclohexanol and cyclohexanone, and a solvent was required for the reaction to proceed.
[0006] This invention provides a photocatalyst and its preparation method. A noble metal I and an active metal II are supported on a titanium dioxide nanotube carrier to prepare a photocatalyst suitable for the oxidation of cyclohexane to adipic acid. The cyclohexane conversion rate is greater than 12%, and the photocatalyst can be reused multiple times. The reaction temperature and pressure for adipic acid preparation are low, no solvent is required during the reaction, and subsequent product separation is easy. Summary of the Invention
[0007] The purpose of this invention is to provide a photocatalyst and its preparation method, which solves the problems of severe equipment corrosion caused by the use of concentrated nitric acid during the synthesis of adipic acid, and the release of large amounts of nitrogen oxides during the production process, resulting in environmental pollution and ecological damage.
[0008] To address the aforementioned technical problems, this application first provides a photocatalyst, which is prepared by supporting active metal I and active metal II on a titanium-based nanotube support, and is used for the oxidation of cyclohexane to adipic acid. The active metal I is a noble metal, one or two of platinum and palladium, and the active metal II is one or more of cobalt, manganese, copper, and chromium. The support is a titanium-based nanotube, preferably a titanium dioxide nanotube.
[0009] The mass content of active metal I is 0.1-1%, and the mass content of active metal II is 0.1-0.5%.
[0010] Secondly, this invention provides a method for preparing the above-mentioned photocatalyst, the preparation steps of which are as follows: 1) Preparation of titanium-based nanotube carriers Titanium material and alkali are added to the reactor, dispersed, heated and reacted, then acid-washed, washed with water until neutral and dried, and finally calcined to obtain the carrier.
[0011] 2) Catalyst Preparation The support, active metal I, and active metal II are placed in a photocatalytic reactor, a solvent is added, the mixture is continuously stirred and nitrogen gas is introduced, and after photoreduction by ultraviolet light is turned on, the product is washed with distilled water and dried and calcined to obtain the catalyst.
[0012] In step (1), the alkali is one or both of sodium hydroxide or potassium hydroxide, and the mass ratio of the alkali to the titanium-based nanotube carrier is 1:1-100.
[0013] The dispersion method described in step (1) is ultrasonic dispersion or shaking table dispersion.
[0014] The heating reaction temperature in step (1) is 110-170℃, the reaction time is 16-48h, the drying time is 80℃ for 5h, the calcination time is 2-10h, and the calcination temperature is 300-500℃.
[0015] The solvent mentioned in step (2) is a mixture of ethanol and water in a mass ratio of 1:1-10, and the amount of solvent added is 50-100 times the mass of the titanium-based nanotubes.
[0016] The ultraviolet lamp mentioned in step (2) is a 350-450W medium-pressure mercury lamp, the photoreduction time is 3-8 hours, the calcination temperature is 500-800℃, and the calcination time is 6-18 hours.
[0017] The ultraviolet lamp mentioned in step (2) is a 350W medium-pressure mercury lamp with a photoreduction time of 3-8 h, a calcination temperature of 500-800℃, and a calcination time of 6-18 h.
[0018] Furthermore, this application provides a method for preparing adipic acid by oxidizing cyclohexane using the above-mentioned photocatalyst. The method involves placing cyclohexane, the catalyst, and the initiator in a photocatalytic reactor, introducing oxygen to carry out the photocatalytic reaction, and then obtaining crude adipic acid. The volume ratio of cyclohexane:catalyst:initiator is (10-100):(1-5):(3-10). The above-mentioned initiators are tert-butyl hydroperoxide and cyclohexanone, wherein the mass ratio of tert-butyl hydroperoxide to cyclohexanone is 1:1-50, the photocatalytic reaction temperature is 60-90℃, the reaction time is 4-12 h, and the oxygen introduction rate is 1L / min.
[0019] Compared with the prior art, the advantages of this invention are: The photocatalyst described in this invention can be applied to the one-step preparation of adipic acid by cyclohexane oxidation, without the need to control the conversion rate and selectivity of KA, and the process route is more optimized than the existing technology; Compared with the existing two-step method for preparing adipic acid from cyclohexane and KA oil, this method eliminates the second step of nitric acid oxidation of KA oil to prepare adipic acid, reducing equipment corrosion and environmental pollution. The photocatalyst described in this invention provides a milder temperature and pressure for the one-step oxidation of cyclohexane to adipic acid, and the photocatalyst can be recycled. The photocatalyst of this invention is made from two active metals, which makes the catalytic activity higher. It does not require the use of solvents to further disperse the reaction raw materials, and the content and ratio of active metals are controlled to reduce the side reactions of adipic acid. Detailed Implementation Example 1
[0020] Photocatalyst preparation: (1) Weigh 5 g TiO2 (P25) and place it in a high-pressure reactor containing 200 mL of 10 mol / L NaOH. Disperse it ultrasonically at 20 °C for 20 min. After sealing, place it in an oven and keep it at 140 °C for 24 h. Cool it naturally to room temperature, discard the supernatant, and grind the TiO2 solid into a fine powder. Adjust the pH to 2.5 with 0.1 mol / L HCl, stir and acid wash at room temperature for 2 h, then wash with distilled water until neutral, dry at 80 °C for 5 h, and calcine at 300 °C for 5 h to obtain the photocatalyst support.
[0021] (2) To the support obtained above, add 0.06 g of H2PtCl6·6H2O and 0.045 g of cobalt acetate, then add ethanol and distilled water to a final volume of 400 mL. Place the mixture in a photocatalyst synthesis reactor and stir continuously until homogeneous. Purge with nitrogen for 30 min to remove oxygen from the mixture. Turn on the ultraviolet lamp and reduce the mixture with a 350 W medium-pressure mercury lamp in a nitrogen atmosphere for 6 h. Wash the product with distilled water and dry at 500 °C for 12 h to obtain the Co / Pt-TiO2 photocatalyst.
[0022] (P25 is titanium dioxide produced by Degussa, Germany, and the same applies below.) Preparation of adipic acid: 500 mL of cyclohexane, 10 g of Co / Pt-TiO2 photocatalyst, 2 mL of tert-butyl hydrogen peroxide, and 50 mL of cyclohexanone were added to a photocatalytic reactor as initiators. A 350 W medium-pressure mercury lamp was used as the light source, and oxygen was continuously introduced at a rate of 1 L / min to keep the photocatalyst in suspension. After reacting at 60 °C for 4 h, the mixture was cooled to room temperature, filtered, and analyzed. The results showed that the cyclohexane conversion rate was 13.2% and the adipic acid selectivity was 80.5%. Example 2
[0023] Photocatalyst preparation: (1) Weigh 5 g TiO2 (P25) and place it in a high-pressure reactor containing 200 mL of 10 mol / L NaOH. Disperse it ultrasonically at 20 °C for 20 min, seal it, and place it in an oven. Keep it at 100 °C for 20 h. Cool it naturally to room temperature, discard the supernatant, and grind the TiO2 solid into a fine powder. Adjust the pH to 2.5 with 0.1 mol / L HCl, stir and acid wash at room temperature for 2 h, then wash it with distilled water until neutral, dry it at 80 °C for 5 h, and calcine it at 300 °C for 5 h to obtain the photocatalyst support.
[0024] (2) To the support obtained above, add 0.06 g of H2PtCl6·6H2O and 0.045 g of cobalt acetate, then add ethanol and distilled water to a final volume of 400 mL. Place the mixture in a photocatalyst synthesis reactor and stir continuously until homogeneous. Purge with nitrogen for 30 min to remove oxygen from the mixture. Turn on the ultraviolet lamp and reduce the mixture with a 350 W medium-pressure mercury lamp in a nitrogen atmosphere for 4 h. Wash the product with distilled water and dry at 600 °C for 12 h to obtain the Co / Pt-TiO2 photocatalyst.
[0025] Preparation of adipic acid: 500 mL of cyclohexane, 10 g of Co / Pt-TiO2 photocatalyst, 2 mL of tert-butyl hydrogen peroxide, and 50 mL of cyclohexanone were added to a photocatalytic reactor as initiators. A 350 W medium-pressure mercury lamp was used as the light source, and oxygen was continuously introduced at a rate of 1 L / min to keep the photocatalyst in suspension. After reacting at 60 °C for 6 h, the mixture was cooled to room temperature, and the reaction mixture was removed, filtered, and analyzed. The results showed that the cyclohexane conversion rate was 12.5% and the adipic acid selectivity was 86.6%. Example 3
[0026] Photocatalyst preparation: (1) Weigh 5 g TiO2 (P25) and place it in a high-pressure reactor containing 150 mL of 1 mol / L NaOH. Disperse it ultrasonically at 20 °C for 20 min, seal it, and place it in an oven. Keep it at 130 °C for 16 h. Cool it naturally to room temperature, discard the supernatant, and grind the TiO2 solid into a fine powder. Adjust the pH to 2.5 with 0.1 mol / L HCl, stir and acid wash at room temperature for 2 h, then wash it with distilled water until neutral, dry it at 80 °C for 5 h, and calcine it at 350 °C for 5 h to obtain the photocatalyst support.
[0027] (2) To the support obtained above, add 0.06 g of H2PtCl6·6H2O and 0.047 g of manganese acetate, then add ethanol and distilled water to a final volume of 400 mL. Place the mixture in a photocatalyst synthesis reactor and stir continuously until homogeneous. Purge with nitrogen for 30 min to remove oxygen from the mixture. Turn on the ultraviolet lamp and reduce the mixture with a 350 W medium-pressure mercury lamp in a nitrogen atmosphere for 5 h. Wash the product with distilled water and dry at 700 °C for 12 h to obtain the Mn / Pt-TiO2 photocatalyst.
[0028] Preparation of adipic acid: 500 mL of cyclohexane, 10 g of Mn / Pt-TiO2 photocatalyst, 2 mL of tert-butyl hydrogen peroxide, and 50 mL of cyclohexanone were added to a photocatalytic reactor as initiators. A 350 W medium-pressure mercury lamp was used as the light source, and oxygen was continuously introduced at a rate of 1 L / min to keep the photocatalyst in suspension. After reacting at 70 °C for 8 h, the mixture was cooled to room temperature, and the reaction mixture was removed, filtered, and analyzed. The results showed that the cyclohexane conversion rate was 12.6% and the adipic acid selectivity was 83.4%. Example 4
[0029] Photocatalyst preparation: (1) Weigh 5 g TiO2 (P25) and place it in a high-pressure reactor containing 800 mL of 15 mol / L NaOH. Disperse it ultrasonically at 20 °C for 20 min, seal it, and place it in an oven. Keep it at 110 °C for 28 h. Cool it naturally to room temperature, discard the supernatant, and grind the TiO2 solid into a fine powder. Adjust the pH to 2.5 with 0.1 mol / L HCl, stir and acid wash at room temperature for 2 h, then wash it with distilled water until neutral, dry it at 80 °C for 5 h, and calcine it at 350 °C for 3 h to obtain the photocatalyst support.
[0030] (2) To the support obtained above, add 0.06 g of H2PtCl6·6H2O and 0.047 g of manganese acetate, then add ethanol and distilled water to a final volume of 400 mL. Place the mixture in a photocatalyst synthesis reactor and stir continuously until homogeneous. Purge with nitrogen for 30 min to remove oxygen from the mixture. Turn on the ultraviolet lamp and reduce the mixture with a 350 W medium-pressure mercury lamp in a nitrogen atmosphere for 3 h. Wash the product with distilled water and dry at 800 °C for 12 h to obtain the Mn / Pt-TiO2 photocatalyst.
[0031] Preparation of adipic acid: 500 mL of cyclohexane, 10 g of Mn / Pt-TiO2 photocatalyst, 2 mL of tert-butyl hydrogen peroxide, and 50 mL of cyclohexanone were added to a photocatalytic reactor as initiators. A 350 W medium-pressure mercury lamp was used as the light source, and oxygen was continuously introduced at a rate of 1 L / min to keep the photocatalyst in suspension. After reacting at 70 °C for 10 h, the mixture was cooled to room temperature, and the reaction mixture was removed, filtered, and analyzed. The results showed that the cyclohexane conversion rate was 12.3% and the adipic acid selectivity was 82.8%. Example 5
[0032] Photocatalyst preparation: (1) Weigh 5 g TiO2 (P25) and place it in a high-pressure reactor containing 200 mL of 10 mol / L KOH. Disperse it ultrasonically at 20 °C for 20 min. After sealing, place it in an oven and keep it at 150 °C for 32 h. Cool it naturally to room temperature, discard the supernatant, and grind the TiO2 solid into a fine powder. Adjust the pH to 2.5 with 0.1 mol / L HCl, stir and acid wash at room temperature for 2 h, then wash with distilled water until neutral, dry at 80 °C for 5 h, and calcine at 350 °C for 3 h to obtain the photocatalyst support.
[0033] (2) To the carrier obtained above, add 0.04 g of palladium chloride and 0.047 g of copper acetate, then add ethanol and distilled water to a final volume of 400 mL. Place the mixture in a photocatalyst synthesis reactor and stir continuously until homogeneous. Purge with nitrogen gas for 30 min to remove oxygen from the mixture. Turn on the ultraviolet lamp and reduce the mixture with a 350 W medium-pressure mercury lamp in a nitrogen atmosphere for 7 h. Wash the product with distilled water and dry at 500 °C for 12 h to obtain the Cu / Pd-TiO2 photocatalyst.
[0034] Preparation of adipic acid: 500 mL of cyclohexane, 10 g of Cu / Pd-TiO2 photocatalyst, 2 mL of tert-butyl hydrogen peroxide, and 50 mL of cyclohexanone were added to a photocatalytic reactor as initiators. A 350 W medium-pressure mercury lamp was used as the light source, and oxygen was continuously introduced at a rate of 1 L / min to keep the photocatalyst in suspension. After reacting at 80 °C for 12 h, the mixture was cooled to room temperature, filtered, and analyzed. The results showed that the cyclohexane conversion rate was 13.4% and the adipic acid selectivity was 79.7%. Example 6
[0035] Photocatalyst preparation: (1) Weigh 5 g TiO2 (P25) and place it in a high-pressure reactor containing 200 mL of 10 mol / L KOH. Disperse it ultrasonically at 20 °C for 20 min. After sealing, place it in an oven and keep it at 160 °C for 36 h. Cool it naturally to room temperature, discard the supernatant, and grind the TiO2 solid into a fine powder. Adjust the pH to 2.5 with 0.1 mol / L HCl, stir and acid wash at room temperature for 2 h, then wash with distilled water until neutral, dry at 80 °C for 5 h, and calcine at 400 °C for 3 h to obtain the photocatalyst support.
[0036] (2) To the carrier obtained above, add 0.04 g of palladium chloride and 0.047 g of copper acetate, then add ethanol and distilled water to a final volume of 400 mL. Place the mixture in a photocatalyst synthesis reactor and stir continuously until homogeneous. Purge with nitrogen for 30 min to remove oxygen from the mixture. Turn on the ultraviolet lamp and reduce the mixture with a 350 W medium-pressure mercury lamp in a nitrogen atmosphere for 8 h. Wash the product with distilled water and dry at 600 °C for 12 h to obtain the Cu / Pd-TiO2 photocatalyst.
[0037] Preparation of adipic acid: 500 mL of cyclohexane, 10 g of Cu / Pd-TiO2 photocatalyst, 2 mL of tert-butyl hydrogen peroxide, and 50 mL of cyclohexanone were added to a photocatalytic reactor as initiators. A 350 W medium-pressure mercury lamp was used as the light source, and oxygen was continuously introduced at a rate of 1 L / min to keep the photocatalyst in suspension. After reacting at 80 °C for 4 h, the mixture was cooled to room temperature, and the reaction mixture was removed, filtered, and analyzed. The results showed that the cyclohexane conversion rate was 13.6% and the adipic acid selectivity was 76.6%. Example 7
[0038] Photocatalyst preparation: (1) Weigh 5 g TiO2 (P25) and place it in a high-pressure reactor containing 200 mL of 10 mol / L KOH. Disperse it ultrasonically at 20 °C for 20 min. After sealing, place it in an oven and keep it at 170 °C for 42 h. Cool it naturally to room temperature, discard the supernatant, and grind the TiO2 solid into a fine powder. Adjust the pH to 2.5 with 0.1 mol / L HCl, stir and acid wash at room temperature for 2 h, then wash with distilled water until neutral, dry at 80 °C for 5 h, and calcine at 400 °C for 3 h to obtain the photocatalyst support.
[0039] (2) To the support obtained above, add 0.04 g of palladium chloride and 0.045 g of cobalt acetate, then add ethanol and distilled water to a final volume of 400 mL. Place the mixture in a photocatalyst synthesis reactor and stir continuously until homogeneous. Purge with nitrogen gas for 30 min to remove oxygen from the mixture. Turn on the ultraviolet lamp and reduce the mixture with a 350 W medium-pressure mercury lamp in a nitrogen atmosphere for 6 h. Wash the product with distilled water and dry at 700 °C for 12 h to obtain the Co / Pd-TiO2 photocatalyst.
[0040] Preparation of adipic acid: 500 mL of cyclohexane, 10 g of Co / Pd-TiO2 photocatalyst, 2 mL of tert-butyl hydrogen peroxide, and 50 mL of cyclohexanone were added to a photocatalytic reactor as initiators. A 350 W medium-pressure mercury lamp was used as the light source, and oxygen was continuously introduced at a rate of 1 L / min to keep the photocatalyst in suspension. After reacting at 90 °C for 6 h, the mixture was cooled to room temperature, filtered, and analyzed. The results showed that the cyclohexane conversion rate was 13.0% and the adipic acid selectivity was 78.2%.
[0041] Example 8: Preparation of adipic acid Using the photocatalyst prepared in Example 1, 500 mL of cyclohexane, 10 g of Co / Pt-TiO2 photocatalyst, 2 mL of tert-butyl hydrogen peroxide, and 50 mL of cyclohexanone were added to a photocatalytic reactor as initiators. A 350 W medium-pressure mercury lamp was used as the light source, and oxygen was continuously introduced at a rate of 1 L / min to keep the photocatalyst in suspension. After reacting at 60 °C for 4 h, the mixture was cooled to room temperature, filtered, and the filtered photocatalyst was subjected to 5 cyclohexane oxidation reactions before analysis. The results showed a cyclohexane conversion rate of 11.8% and an adipic acid selectivity of 76.9%.
[0042] Comparative Example 1: Photocatalyst preparation: (1) Weigh 5 g TiO2 (P25) and place it in a high-pressure reactor containing 200 mL of 10 mol / L NaOH. Disperse it ultrasonically at 20 °C for 20 min. After sealing, place it in an oven and keep it at 140 °C for 24 h. Cool it naturally to room temperature, discard the supernatant, and grind the TiO2 solid into a fine powder. Adjust the pH to 2.5 with 0.1 mol / L HCl, stir and acid wash at room temperature for 2 h, then wash with distilled water until neutral, dry at 80 °C for 5 h, and calcine at 300 °C for 5 h to obtain the photocatalyst support.
[0043] (2) Add 0.045 g of cobalt acetate to the carrier obtained above, then add ethanol and distilled water to a final volume of 400 mL. Place the mixture in a photocatalyst synthesis reactor and stir continuously until homogeneous. Purge with nitrogen gas for 30 min to remove oxygen from the mixture. Turn on the ultraviolet lamp and reduce the mixture with a 350 W medium-pressure mercury lamp in a nitrogen atmosphere for 6 h. Wash the product with distilled water and dry at 500 °C for 12 h to obtain the Co-TiO2 photocatalyst.
[0044] Preparation of adipic acid: 500 mL of cyclohexane, 10 g of Co-TiO2 photocatalyst, 2 mL of tert-butyl hydrogen peroxide, and 50 mL of cyclohexanone were added to a photocatalytic reactor as initiators. A 350 W medium-pressure mercury lamp was used as the light source, and oxygen was continuously introduced at a rate of 1 L / min to keep the photocatalyst in suspension. After reacting at 60 °C for 4 h, the mixture was cooled to room temperature, and the reaction mixture was removed, filtered, and analyzed. The results showed that the cyclohexane conversion rate was 6.8% and the adipic acid selectivity was 75.8%.
[0045] Comparative Example 2: Photocatalyst preparation: (1) Weigh 5 g TiO2 (P25) and place it in a high-pressure reactor containing 200 mL of 10 mol / L NaOH. Disperse it ultrasonically at 20 °C for 20 min. After sealing, place it in an oven and keep it at 140 °C for 24 h. Cool it naturally to room temperature, discard the supernatant, and grind the TiO2 solid into a fine powder. Adjust the pH to 2.5 with 0.1 mol / L HCl, stir and acid wash at room temperature for 2 h, then wash with distilled water until neutral, dry at 80 °C for 5 h, and calcine at 300 °C for 5 h to obtain the photocatalyst support.
[0046] (2) Add 0.06 g of H2PtCl6·6H2O to the carrier obtained above, then add ethanol and distilled water to 400 mL, place it in a photocatalyst synthesis reactor, stir continuously until uniform, and purge with nitrogen for 30 min to remove oxygen from the mixture. Turn on the ultraviolet lamp, and reduce with a 350 W medium-pressure mercury lamp for 6 h in a nitrogen atmosphere. Wash the product with distilled water and dry at 500 °C for 12 h to obtain the Pt-TiO2 photocatalyst.
[0047] Preparation of adipic acid: 500 mL of cyclohexane, 10 g of Pt-TiO2 photocatalyst, 2 mL of tert-butyl hydrogen peroxide, and 50 mL of cyclohexanone were added to a photocatalytic reactor as initiators. A 350 W medium-pressure mercury lamp was used as the light source, and oxygen was continuously introduced at a rate of 1 L / min to keep the photocatalyst in suspension. After reacting at 60 °C for 4 h, the mixture was cooled to room temperature, filtered, and analyzed. The results showed that the cyclohexane conversion rate was 9.5% and the adipic acid selectivity was 50.3%.
[0048] Comparative Example 3: Photocatalyst preparation: (1) Weigh 5 g TiO2 (P25) and place it in a high-pressure reactor containing 200 mL of 10 mol / L NaOH. Disperse it ultrasonically at 20 °C for 20 min. After sealing, place it in an oven and keep it at 140 °C for 24 h. Cool it naturally to room temperature, discard the supernatant, and grind the TiO2 solid into a fine powder. Adjust the pH to 2.5 with 0.1 mol / L HCl, stir and acid wash at room temperature for 2 h, then wash with distilled water until neutral, dry at 80 °C for 5 h, and calcine at 300 °C for 5 h to obtain the photocatalyst support.
[0049] (2) To the support obtained above, add 0.06 g of H2PtCl6·6H2O and 0.045 g of cobalt acetate, then add ethanol and distilled water to a final volume of 400 mL. Place the mixture in a photocatalyst synthesis reactor and stir continuously until homogeneous. Purge with nitrogen for 30 min to remove oxygen from the mixture. Turn on the ultraviolet lamp and reduce the mixture with a 350 W medium-pressure mercury lamp in a nitrogen atmosphere for 6 h. Wash the product with distilled water and dry at 500 °C for 12 h to obtain the Co / Pt-TiO2 photocatalyst.
[0050] Preparation of adipic acid: 500 mL of cyclohexane and 10 g of Co / Pt-TiO2 photocatalyst were added to a photocatalytic reactor. A 350 W medium-pressure mercury lamp was used as the light source, and oxygen was continuously introduced at a rate of 1 L / min to keep the photocatalyst in suspension. After reacting at 60 °C for 4 h, the mixture was cooled to room temperature, filtered, and analyzed. The results showed that the cyclohexane conversion rate was 5.2% and the adipic acid selectivity was 53.1%.
[0051] Comparative Example 4: Photocatalyst preparation: (1) Weigh 5 g TiO2 (P25) and place it in a high-pressure reactor containing 200 mL of 10 mol / L NaOH. Disperse it ultrasonically at 20 °C for 20 min. After sealing, place it in an oven and keep it at 140 °C for 24 h. Cool it naturally to room temperature, discard the supernatant, and grind the TiO2 solid into a fine powder. Adjust the pH to 2.5 with 0.1 mol / L HCl, stir and acid wash at room temperature for 2 h, then wash with distilled water until neutral, dry at 80 °C for 5 h, and calcine at 500 °C for 5 h to obtain the photocatalyst support.
[0052] (2) To the support obtained above, add 0.06 g of H2PtCl6·6H2O and 0.045 g of cobalt acetate, then add ethanol and distilled water to a final volume of 400 mL. Place the mixture in a photocatalyst synthesis reactor and stir continuously until homogeneous. Purge with nitrogen for 30 min to remove oxygen from the mixture. Turn on the ultraviolet lamp and reduce the mixture with a 350 W medium-pressure mercury lamp in a nitrogen atmosphere for 6 h. Wash the product with distilled water and dry at 500 °C for 12 h to obtain the Co / Pt-TiO2 photocatalyst.
[0053] Preparation of adipic acid: 500 mL of cyclohexane, 10 g of Co / Pt-TiO2 photocatalyst, 2 mL of tert-butyl hydrogen peroxide, and 50 mL of cyclohexanone were added to a photocatalytic reactor as initiators. A 350 W medium-pressure mercury lamp was used as the light source, and oxygen was continuously introduced at a rate of 1 L / min to keep the photocatalyst in suspension. After reacting at 60 °C for 4 h, the mixture was cooled to room temperature, filtered, and analyzed. The results showed that the cyclohexane conversion rate was 8.8% and the adipic acid selectivity was 62.1%.
[0054] Comparative Example 5: Photocatalyst preparation: (1) Weigh 5 g TiO2 (P25) and place it in a high-pressure reactor containing 200 mL of 10 mol / L NaOH. Disperse it ultrasonically at 20 °C for 20 min. After sealing, place it in an oven and keep it at 140 °C for 24 h. Cool it naturally to room temperature, discard the supernatant, and grind the TiO2 solid into a fine powder. Adjust the pH to 2.5 with 0.1 mol / L HCl, stir and acid wash at room temperature for 2 h, then wash with distilled water until neutral, dry at 80 °C for 5 h, and calcine at 300 °C for 5 h to obtain the photocatalyst support.
[0055] (2) To the support obtained above, add 0.06 g of H2PtCl6·6H2O and 0.045 g of cobalt acetate, then add ethanol and distilled water to a final volume of 400 mL. Place the mixture in a photocatalyst synthesis reactor and stir continuously until homogeneous. Purge with nitrogen for 30 min to remove oxygen from the mixture. Turn on the ultraviolet lamp and reduce the mixture with a 350 W medium-pressure mercury lamp in a nitrogen atmosphere for 6 h. Wash the product with distilled water and dry at 300 °C for 12 h to obtain the Co / Pt-TiO2 photocatalyst.
[0056] Preparation of adipic acid: 500 mL of cyclohexane, 10 g of Co / Pt-TiO2 photocatalyst, 2 mL of tert-butyl hydrogen peroxide, and 50 mL of cyclohexanone were added to a photocatalytic reactor as initiators. A 350 W medium-pressure mercury lamp was used as the light source, and oxygen was continuously introduced at a rate of 1 L / min to keep the photocatalyst in suspension. After reacting at 60 °C for 4 h, the mixture was cooled to room temperature, filtered, and analyzed. The results showed that the cyclohexane conversion rate was 10.2% and the adipic acid selectivity was 68.5%.
[0057] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A photocatalyst, characterized in that: The photocatalyst is prepared by supporting active metal I and active metal II on a titanium-based nanotube support and is used for the oxidation of cyclohexane to adipic acid. The active metal I is a noble metal, one or two of platinum and palladium, and the active metal II is one or more of cobalt, manganese, copper and chromium. The support is a titanium-based nanotube.
2. The photocatalyst according to claim 1, characterized in that... The mass content of active metal I is 0.1-1%, the mass content of active metal II is 0.1-0.5%, and the mass ratio of active metal I to active metal II is 0.1:
10.
3. The method for preparing the photocatalyst according to claim 1 or 2, characterized in that... The preparation steps are as follows: 1) Preparation of titanium-based nanotube carriers Titanium material and alkali are added to the reactor, dispersed, heated and reacted, then acid washed, washed with water until neutral and dried, and then calcined to obtain titanium-based nanotube carriers. 2) Catalyst Preparation Titanium-based nanotube supports were placed in a photocatalytic reactor with active metal I and active metal II. Solvent was added, and the mixture was continuously stirred and nitrogen gas was introduced. After photoreduction by ultraviolet light, the product was washed with distilled water and dried and calcined to obtain the catalyst.
4. The method for preparing the photocatalyst according to claim 3, characterized in that, The alkali mentioned in step (1) is one or both of sodium hydroxide or potassium hydroxide, and the mass ratio of the alkali to the titanium material is 1-100:
1.
5. The method for preparing the photocatalyst according to claim 3, characterized in that, The dispersion method described in step (1) is ultrasonic dispersion or shaking table dispersion.
6. The method for preparing the photocatalyst according to claim 3, characterized in that, The heating reaction temperature in step (1) is 110-170℃, the reaction time is 16-48 h, the drying time is 80℃ for 5 h, the calcination time is 2-10 h, and the calcination temperature is 300-500℃.
7. The method for preparing the photocatalyst according to claim 3, characterized in that, The solvent mentioned in step (2) is a mixture of ethanol and water in a mass ratio of 1:1-10, and the amount of solvent added is 50-100 times the mass of the titanium-based nanotubes.
8. The method for preparing the photocatalyst according to claim 3, characterized in that, The ultraviolet lamp mentioned in step (2) is a 350W medium-pressure mercury lamp with a photoreduction time of 3-8 h, a calcination temperature of 500-800℃, and a calcination time of 6-18 h.
9. A method for preparing adipic acid by cyclohexane oxidation, characterized in that... The photocatalyst prepared by any one of claims 1-8 is obtained by placing cyclohexane, catalyst and initiator in a photocatalytic reactor and introducing oxygen to carry out a photocatalytic reaction; wherein the volume ratio of cyclohexane:catalyst:initiator is (10-100):(1-5):(3-10).
10. The method according to claim 9, characterized in that, The initiators are tert-butyl hydroperoxide and cyclohexanone, with a mass ratio of tert-butyl hydroperoxide to cyclohexanone of 1:1-50. The photocatalytic reaction temperature is 60-90℃, the reaction time is 4-12 h, and the oxygen introduction rate is 1 L / min.