Tungsten-bismuth composite oxide catalyst, preparation and use thereof
By using a tungsten-bismuth composite oxide catalyst, the problems of poor catalyst selectivity and stability in the existing glutaraldehyde preparation were solved, achieving efficient and low-cost glutaraldehyde production, which is suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2022-11-28
- Publication Date
- 2026-05-12
AI Technical Summary
Existing methods for preparing glutaraldehyde suffer from poor catalyst selectivity, low yield, and poor stability, making it difficult to improve the production efficiency of glutaraldehyde.
A tungsten-bismuth composite oxide catalyst was used to prepare glutaraldehyde via a simple preparation method, avoiding the use of surfactants and long-term low-temperature crystallization. The catalyst was used for the catalytic oxidation of 1,2-epoxycyclopentane to glutaraldehyde. The molar ratio of hydrogen peroxide to 1,2-epoxycyclopentane was optimized to be 1-1.5, the reaction temperature was 25-80℃, and the reaction time was 2-12 hours.
It achieves high conversion rate (>94%) of 1,2-epoxycyclopentane and high selectivity (up to 96%) of glutaraldehyde. The catalyst has good stability, is easy to separate, and has low cost, making it suitable for industrial applications.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of solid-liquid multiphase catalytic reactions, specifically to a highly efficient catalyst for the catalytic oxidation of 1,2-epoxycyclopentane to glutaraldehyde, and a method for using the catalyst to produce glutaraldehyde. Background Technology
[0002] Glutaraldehyde (GA) is a colorless or pale yellow oily liquid with a pungent odor. It is readily soluble in water and ethanol, soluble in benzene, non-flammable, non-volatile, and unstable in air. It can be oxidized by air at room temperature and readily undergoes condensation and polymerization reactions. It is an important saturated straight-chain aliphatic dialdehyde, a crucial fine chemical product and intermediate, and has cross-linking and protein-fixing properties. It is a highly effective and low-toxicity sterilizing agent, an excellent leather tanning agent, a color picture tube hardening agent, and an organic synthesis agent, widely used in biomedical engineering, cellular immunology, biochemistry, leather chemistry, histochemistry, microbial industry, and environmental protection.
[0003] Existing methods for preparing glutaraldehyde mainly include the pyridine method, the pyran method, the pentylene glycol oxidation method, the glutaric acid reduction method, and the cyclopentene oxidation method. The earliest method used for industrial production was the pyridine method. This method involves reducing pyridine to dihydropyridine, then treating it with hydroxylamine to obtain glutaroxime, and finally using sodium nitrite and hydrochloric acid to convert glutaroxime to glutaraldehyde. This method achieves a conversion rate of 90%, but the yield is less than 50%. This method has been phased out due to its high raw material consumption, high cost, high pollution, and poor product quality. The pyran method uses acrolein and vinyl ether as raw materials to cyclize 2-ethoxy-3,4-dihydropyran, followed by hydrolysis to open the ring and form glutaraldehyde. This method suffers from high raw material costs, a long process route, and low product yield (e.g., patent CN102066302A). Although the pentylene glycol oxidation method has a short reaction route, it is also difficult to industrialize due to its disadvantages such as difficulty in controlling the oxidation depth, low yield, and high cost caused by raw material shortages. The glutaric acid process utilizes glutaric acid, a byproduct of adipic acid production, as a raw material. Palladium is used as a catalyst, and tert-ammonia is used as an auxiliary agent to reduce glutaric acid to glutaraldehyde, with a yield of 55-88%. Compared to the existing pyran process, this method can reduce costs by 20%, but it currently suffers from a short catalyst lifespan.
[0004] Cyclopentene oxidation is a widely studied and currently the most promising synthetic route. The main routes for the catalytic oxidation of cyclopentene to glutaraldehyde include ozone oxidation, oxide oxidation, cyclopentyl-o-diol oxidation, air oxidation, and hydrogen peroxide oxidation. Among these, hydrogen peroxide is used as the oxidant due to its advantages such as low cost, abundant raw material supply, clean process, short route, and mild conditions, thus showing broad development prospects. The process of cyclopentene oxidation to glutaraldehyde under hydrogen peroxide involves cyclopentene first reacting to form 1,2-epoxycyclopentane, then 1,2-epoxycyclopentane converting to the intermediate β-hydroxycyclopentylhydrogen peroxide, which then rearranges to glutaraldehyde. Currently, the catalysts used in this reaction are typically molybdenum-based compounds, tungsten-based compounds, heteropoly acids, composite metal oxides, and tungsten-based molecular sieve catalysts with the active component loaded onto mesoporous molecular sieves.
[0005] Considering the ease of catalyst separation, the research on tungsten-based supported catalysts and tungsten-based molecular sieve catalysts has received widespread attention from scholars. Chinese patent CN1425498 provides a tungsten-containing catalyst supported on TiO2 microspheres via closed crystallization, achieving glutaraldehyde yields ranging from a high of 69.4% to a low of 60.3%. Chinese patent CN1680032A discloses a method for synthesizing a tungsten-based molecular sieve catalyst for the selective catalytic oxidation of cyclopentene to glutaraldehyde using hydrogen peroxide as an oxidant. This method involves in-situ introduction of an active tungsten source into a synthesized all-silica mesoporous molecular sieve framework. The yield of the target product, glutaraldehyde, is 56.9-75.1%, and the selectivity is 73.5%-82%. The catalytic effect is generally moderate, and the catalyst activity and selectivity need further improvement. In the preparation of catalyst CN110372483A, the template agent TPABr was added. The highest yield of the target product glutaraldehyde was 87.1%, and the selectivity of glutaraldehyde was 87.1%. Although its catalytic activity was improved, the stability of the catalyst was poor, and the activity of the catalyst decreased significantly after three cycles. Based on the two patents mentioned above, patent CN113813986A continues the method of in-situ introducing an active tungsten source into the all-silica mesoporous molecular sieve framework. Using Pluronic P123 triblock polymer E020P070E020 as a template agent, a catalyst precursor was prepared by low-temperature long-time crystallization (68-74h), thereby obtaining a tungsten-based molecular sieve catalyst. This catalyst is used in the above reaction and has high catalytic activity, with the highest yield of the target product glutaraldehyde reaching 89.1% and a selectivity of 91.2%. However, the catalyst stability is also poor, and the activity of the catalyst decreases significantly after three cycles. At the same time, the use of Pluronic P123 triblock polymer E020P070E020 increases the catalyst cost, making it difficult to achieve industrialization. CN114426468A employs a three-stage experiment using tungsten-based heterogeneous catalysts W-SBA-15 with varying acid strengths (WO3 mass fractions of 20-25%, 15-20%, and 10-15%, respectively). By adjusting the amount of hydrogen peroxide added and the concentration of hydrogen peroxide on the catalyst surface, the reaction process is controlled, improving selectivity. The conversion rate of cyclopentene is greater than 98%, and the yield of glutaraldehyde exceeds 80%. However, this method also suffers from the problems of poor catalyst stability and high cost associated with patent CN113813986A.
[0006] In summary, glutaraldehyde, as an important chemical intermediate and raw material, has always been limited in production due to inefficient process conditions and catalytic methods, resulting in consistently low yields. Developing superior catalysts and optimal preparation methods for glutaraldehyde is of paramount importance for the industrial production of glutaraldehyde and the development of its downstream products.
[0007] To address the problems existing in the current glutaraldehyde preparation systems: 1) Heterogeneous catalysts for the direct catalytic oxidation of cyclopentene to glutaraldehyde generally suffer from poor selectivity, low yield, and poor stability. 2) Reports on the catalytic oxidation of 1,2-epoxycyclopentane to glutaraldehyde are scarce. Based on our research group's years of experience in the catalytic epoxidation of olefins using heterogeneous phase transfer catalysts, this invention provides a catalyst and method for the catalytic oxidation of 1,2-epoxycyclopentane, a product of olefin epoxidation, to glutaraldehyde, in order to overcome the shortcomings of existing technologies. Summary of the Invention
[0008] To overcome the shortcomings of the existing technology, this invention provides a tungsten-bismuth composite oxide catalyst for the catalytic oxidation of 1,2-epoxycyclopentane (a product of cyclopentene catalytic oxidation) to glutaraldehyde, and a method for using this catalyst in the production of glutaraldehyde. The catalyst of this invention exhibits good stability, maintaining high mechanical strength and chemical stability even during prolonged reactions. It also boasts advantages such as simple preparation method, low raw material cost, and easy scalability. When used in the catalytic oxidation of 1,2-epoxycyclopentane to glutaraldehyde, the catalyst demonstrates high conversion of 1,2-epoxycyclopentane, good selectivity and yield of glutaraldehyde, good catalyst stability, and easy separation, exhibiting significant industrial application value.
[0009] This tungsten-bismuth composite oxide catalyst has the following advantages:
[0010] (1) The catalyst preparation process does not require the addition of surfactants (TPABr or Pluronic P123 triblock polymer), low-temperature long-term crystallization process, or expensive tetraethyl orthosilicate silicon source. The catalyst has low cost and simple preparation process.
[0011] (2) Used in the catalytic oxidation of 1,2-epoxycyclopentane to prepare glutaraldehyde, the conversion rate of 1,2-epoxycyclopentane is >94%, and the selectivity of glutaraldehyde is the highest at 96%.
[0012] (3) The molar ratio of hydrogen peroxide to 1,2-epoxycyclopentane is 1-1.5, preferably 1.1-1.3. This avoids the product separation problems caused by excessive use of hydrogen peroxide. (For example, although the yield of glutaraldehyde in CN113813986A is the highest at 89.1%, the molar ratio of hydrogen peroxide to cyclopentene in its catalytic system is 2:1. An explosion occurred during the separation process of excess hydrogen peroxide, so 1 equivalent of calcium hydroxide needs to be added in the post-treatment to remove the hydrogen peroxide.)
[0013] (4) The obtained tungsten-bismuth composite oxide catalyst has good stability. After being recycled 10 times, the catalyst activity and selectivity remain basically unchanged.
[0014] Technical solution of the present invention
[0015] A method for preparing a tungsten-bismuth composite oxide catalyst includes the following steps:
[0016] (1) Mix the Al2O3 precursor and the aqueous solutions of SiO2 and MgO precursors with a dilute nitric acid solution containing bismuth nitrate (bismuth nitrate mass concentration range 10%-50%) and stir and mature at 0-80℃ for 2-24h to obtain a uniform colloidal solution.
[0017] (2) Add the prepared sodium tungstate aqueous solution dropwise to the colloidal solution obtained in step (1), and continue to stir and age at 20-80℃ for 5-24h. The resulting solid solution suspension is spray-dried at 200℃-300℃ to obtain the catalyst precursor.
[0018] The catalyst precursor is calcined by programmed heating or constant temperature, with a temperature of 300℃–750℃, preferably 400℃–650℃, and a calcination time of 2–20h, preferably 2–8h.
[0019] The SiO2 precursor is selected from one or more of silica sol, 60-400 mesh (preferably 200-300 mesh) column chromatography silica gel, and thin layer chromatography silica gel;
[0020] The precursor of MgO is selected from one or more magnesium salts such as magnesium nitrate, magnesium chloride, magnesium hydroxide, or magnesium oxide;
[0021] The precursor of Al2O3 is selected from one or more aluminum salts such as aluminum hydroxide, aluminum nitrate or aluminum trichloride;
[0022] In step (1), the amount of nitric acid added should be such that the pH of the colloidal solution obtained in step (1) is within the range of 0.1-3.
[0023] In step (2), the mass concentration of bismuth nitrate in a certain amount of dilute nitric acid solution containing bismuth nitrate is 10-50%.
[0024] The amount of deionized water added to the system should meet the requirement that the mass fraction of solid content in the solid solution suspension obtained in step (2) is 5%-45%, preferably 10%-30%.
[0025] The tungsten-bismuth composite oxide catalyst is a silica-based composition containing silicon dioxide, magnesium oxide, aluminum oxide, bismuth oxide and tungsten oxide. Relative to the total molar amount of silicon, magnesium, aluminum, bismuth and tungsten, it contains 42 to 80 mol% silicon, 4 to 30 mol% magnesium, 5.5 to 28 mol% aluminum, 6 to 30 mol% bismuth and 4.5 to 35 mol% tungsten.
[0026] The spray drying temperature of the solid solution suspension is 200℃-320℃, preferably 250℃-300℃;
[0027] The catalyst precursor is roasted in one or more of the following atmospheres: hydrogen, oxygen, air, nitrogen, or argon, preferably in an air atmosphere; the heating method can be programmed heating or constant temperature, with the temperature ranging from 300℃ to 750℃, preferably 400℃ to 650℃, and the roasting time being 2-20 hours, preferably 2-8 hours.
[0028] The tungsten-bismuth composite oxide catalyst prepared by the method described above.
[0029] The application of the tungsten-bismuth composite oxide catalyst in the catalytic oxidation of 1,2-epoxycyclopentane to prepare glutaraldehyde.
[0030] The tungsten-bismuth composite oxide catalyst is used for the catalytic oxidation of 1,2-epoxycyclopentane to prepare glutaraldehyde, comprising the following steps: mixing the tungsten-bismuth composite oxide catalyst with a reaction solvent, adding 1,2-epoxycyclopentane, adding hydrogen peroxide solution, and preparing glutaraldehyde through a catalytic oxidation reaction.
[0031] The amount of the tungsten-bismuth composite oxide catalyst added is 1-10% of the mass of 1,2-epoxycyclopentane, preferably 1-5%.
[0032] The molar ratio of hydrogen peroxide to 1,2-epoxycyclopentane is 1-1.5, preferably 1.1-1.3.
[0033] The volume-to-mass ratio of the solvent to 1,2-epoxycyclopentane is 1.5-8:1 (mL:g), preferably 2-4:1 (mL:g).
[0034] The reaction temperature is 25℃-80℃, preferably 25℃-50℃, and the reaction time is 2-12 hours, preferably 2-6 hours;
[0035] The reaction solvent is one or more of isopropanol, tert-amyl alcohol, tert-butanol, ethylene glycol monomethyl ether, and ethylene glycol.
[0036] The catalyst of this invention exhibits excellent stability, maintaining high mechanical strength and chemical stability even during prolonged reactions. It also boasts advantages such as simple preparation method, low raw material cost, and easy scalability. When used in the catalytic oxidation of 1,2-epoxycyclopentane to glutaraldehyde, the catalyst demonstrates high conversion of 1,2-epoxycyclopentane, good selectivity and yield of glutaraldehyde, excellent catalyst stability, and easy separation, exhibiting significant industrial application value. Detailed Implementation
[0037] The present invention will now be described in detail with reference to the embodiments, but the scope of the present invention is not limited to the embodiments described below.
[0038] Example 1
[0039] (1) In a 250mL round-bottom flask, add 10g of 30% silica sol (pH=4), 3.0g of aluminum nitrate nonahydrate, 1.96g of magnesium hydroxide and a nitric acid solution containing 4.0g of bismuth nitrate (composed of 3g of 65% concentrated nitric acid, 10mL of deionized water and 4.0g of bismuth nitrate), 60mL of deionized water, mix well, and keep the mixture at 50℃ for 20h with stirring to obtain a homogeneous colloidal solution (pH range 1.20).
[0040] (2) Add sodium tungstate aqueous solution (prepared from 5.0 g sodium tungstate and 10 mL deionized water) dropwise to the colloidal solution obtained in step (1), and continue to stir and age at 50 °C for 12 h. The resulting solid solution suspension (solid content of 15.8%) is spray-dried at 270 °C-280 °C to obtain the catalyst precursor. Place the solid in a tube furnace and calcine it under nitrogen with a programmed temperature increase. Starting at 30 °C, the temperature is increased to 300 °C at a rate of 2.25 °C / min, and held at 300 °C for 3 h. Then, starting at 300 °C, the temperature is increased to 550 °C at a rate of 2.5 °C / min, and held at 550 °C for 3 h. After natural cooling, SiO2-MgO-Al2O3-Bi2O3-WO3-1 (elemental molar ratio Si:Mg:Al:Bi:W=42.07:28.32:6.74:8.54:14.34) tungsten-bismuth composite oxide catalyst A was obtained.
[0041] Example 2
[0042] (1) In a 250mL round-bottom flask, add 10g of 30% silica sol (pH=4), 3.0g of aluminum nitrate nonahydrate, 2.05g of magnesium nitrate hexahydrate, and a nitric acid solution containing 6.7g of bismuth nitrate (composed of 3g of 65% concentrated nitric acid, 20mL of deionized water, and 6.7g of bismuth nitrate), 40mL of deionized water, mix well, and keep the mixture at 60℃ for 20h with stirring to obtain a homogeneous colloidal solution (pH range 1.05).
[0043] (2) Add sodium tungstate aqueous solution (prepared from 2.5g sodium tungstate and 5mL deionized water) dropwise to the colloidal solution obtained in step (1), and continue to stir and age at 50℃ for 10h. The resulting solid solution suspension (solid content of 18.0%) is spray-dried at 260℃-270℃ to obtain the catalyst precursor. Place the solid in a tube furnace and calcine under nitrogen with programmed temperature rise. Starting at 30℃, the temperature is increased to 300℃ at a rate of 2.25℃ / min, and held at 300℃ for 3h. Then, starting at 300℃, the temperature is increased to 600℃ at a rate of 5℃ / min, and held at 600℃ for 6h. After natural cooling, SiO2-MgO-Al2O3-Bi2O3-WO3-2 (elemental molar ratio Si:Mg:Al:Bi:W=54.63:8.75:8.75:18.56:9.31) tungsten-bismuth composite oxide catalyst B is obtained.
[0044] Example 3
[0045] (1) In a 250mL round-bottom flask, add 3g of 200-300 mesh silica gel, 3.0g of aluminum nitrate nonahydrate, 2.05g of magnesium nitrate hexahydrate and a nitric acid solution containing 6.7g of bismuth nitrate (composed of 3g of 65% concentrated nitric acid, 20mL of deionized water and 6.7g of bismuth nitrate), 50mL of deionized water, mix well, and keep the mixture at 65℃ for 24h with stirring to obtain a homogeneous colloidal solution (pH range of 1.45).
[0046] (2) Add sodium tungstate aqueous solution (prepared from 2.5g sodium tungstate and 5mL deionized water) dropwise to the colloidal solution obtained in step (1), and continue to stir and age at 50℃ for 20h. The resulting solid solution suspension (solid content of 18.0%) is spray-dried at 260℃-270℃ to obtain the catalyst precursor. The solid is placed in a tube furnace and calcined under nitrogen with programmed temperature rise. Starting at 30℃, the temperature is increased to 300℃ at a rate of 2.25℃ / min, and held at 300℃ for 3h. Then, starting at 300℃, the temperature is increased to 600℃ at a rate of 10℃ / min, and held at 600℃ for 4h. After natural cooling, SiO2-MgO-Al2O3-Bi2O3-WO3-3 (elemental molar ratio Si:Mg:Al:Bi:W=54.63:8.75:8.75:18.56:9.31) tungsten-bismuth composite oxide catalyst C is obtained.
[0047] Example 4
[0048] (1) In a 250mL round-bottom flask, add 20g of 30% silica sol (pH=4), 3.0g of aluminum nitrate nonahydrate, 2.05g of magnesium nitrate hexahydrate, and a nitric acid solution containing 3.35g of bismuth nitrate (composed of 5g of 65% concentrated nitric acid, 10mL of deionized water, and 3.35g of bismuth nitrate), 30mL of deionized water, mix well, and keep the mixture at 40℃ for 20h with stirring to obtain a homogeneous colloidal solution (pH range 0.55).
[0049] (2) Add sodium tungstate aqueous solution (prepared from 3.76 g sodium tungstate and 8 mL deionized water) dropwise to the colloidal solution obtained in step (1), and continue to stir and age at 50 °C for 10 h. The resulting solid solution suspension (solid content of 21.3%) is spray-dried at 260 °C-270 °C to obtain the catalyst precursor. Place the solid in a tube furnace and calcine under nitrogen with programmed temperature rise. Starting at 30 °C, the temperature is increased to 300 °C at a rate of 2.25 °C / min, and held at 300 °C for 3 h. Then, starting at 300 °C, the temperature is increased to 700 °C at a rate of 8 °C / min, and held at 700 °C for 5 h. After natural cooling, SiO2-MgO-Al2O3-Bi2O3-WO3-4 (elemental molar ratio Si:Mg:Al:Bi:W=72.82:5.83:5.83:6.18:9.33) tungsten-bismuth composite oxide catalyst D is obtained.
[0050] Comparative Example 1
[0051] (1) In a 100mL round-bottom flask, add 20g of 30% silica sol (pH=4), 3.0g of aluminum nitrate nonahydrate, 2.05g of magnesium nitrate hexahydrate, and a dilute nitric acid solution (composed of 5g of 65% concentrated nitric acid and 10mL of deionized water), along with 30mL of deionized water. Mix thoroughly and maintain the mixture at 40℃ with stirring for 20h to obtain a homogeneous colloidal solution. (pH range: 0.45)
[0052] (2) Add sodium tungstate aqueous solution (prepared from 3.76 g sodium tungstate and 8 mL deionized water) dropwise to the colloidal solution obtained in step (1), and continue to stir and age at 50 °C for 10 h. The resulting solid solution suspension (solid content of 18.10%) is spray-dried at 260 °C-270 °C to obtain the catalyst precursor. Place the solid in a tube furnace and calcine under nitrogen with programmed temperature rise. Starting at 30 °C, the temperature is increased to 300 °C at a rate of 2.25 °C / min, and held at 300 °C for 3 h. Then, starting at 300 °C, the temperature is increased to 600 °C at a rate of 2.5 °C / min, and held at 600 °C for 3 h. After natural cooling, SiO2-MgO-Al2O3-WO3-Comparative Example 1 Cat. (elemental molar ratio Si:Mg:Al:W = 77.62:6.21:6.22:9.95) tungsten-based composite oxide catalyst D1 is obtained.
[0053] Comparative Example 2
[0054] (1) In a 250mL round-bottom flask, add 20g of 30% silica sol (pH=4), 3.0g of aluminum nitrate nonahydrate, 2.05g of magnesium nitrate hexahydrate, and a nitric acid solution containing 3.35g of bismuth nitrate (composed of 5g of 65% concentrated nitric acid, 10mL of deionized water, and 3.35g of bismuth nitrate), 30mL of deionized water, mix well, and keep the mixture at 40℃ for 20h with stirring to obtain a homogeneous colloidal solution (pH range 0.55).
[0055] (2) Add sodium tungstate aqueous solution (prepared from 1.2g sodium tungstate and 8mL deionized water) dropwise to the colloidal solution obtained in step (1), and continue to stir and age at 50℃ for 10h. The resulting solid solution suspension (solid content of 18.9%) is spray-dried at 260℃-270℃ to obtain the catalyst precursor. Place the solid in a tube furnace and calcine it under nitrogen with a programmed temperature increase. Starting at 30℃, the temperature is increased to 300℃ at a rate of 2.25℃ / min, and held at 300℃ for 3h. Then, starting at 300℃, the temperature is increased to 600℃ at a rate of 2.5℃ / min, and held at 600℃ for 3h. After natural cooling, SiO2-MgO-Al2O3-Bi2O3-WO3-Comparative Example 2Cat. (elemental molar ratio Si:Mg:Al:Bi:W=77.76:6.23:6.23:6.60:3.18) tungsten-bismuth composite oxide catalyst D2 was obtained.
[0056] Example 5
[0057] (1) In a 100mL round-bottom flask, add 20g of 30% silica sol (pH=2), 3.0g of aluminum nitrate nonahydrate, 2.05g of magnesium nitrate hexahydrate, and a nitric acid solution containing 3.35g of bismuth nitrate (composed of 2.5g of 65% concentrated nitric acid, 5mL of deionized water, and 3.35g of bismuth nitrate), 10mL of deionized water, mix well, and keep the mixture at 80℃ for 20h with stirring to obtain a homogeneous colloidal solution (pH range 0.95).
[0058] (2) Add sodium tungstate aqueous solution (prepared from 3.76 g sodium tungstate and 8 mL deionized water) dropwise to the colloidal solution obtained in step (1), and continue to stir and age at 50 °C for 10 h. The resulting solid solution suspension (solid content of 31.5%) is spray-dried at 250 °C-260 °C to obtain the catalyst precursor. Place the solid in a tube furnace and calcine under nitrogen with programmed temperature rise. Starting at 30 °C, the temperature is increased to 300 °C at a rate of 2.25 °C / min, and held at 300 °C for 5 h. Then, starting at 300 °C, the temperature is increased to 500 °C at a rate of 2.5 °C / min, and held at 500 °C for 5 h. After natural cooling, SiO2-MgO-Al2O3-Bi2O3-WO3-5 (elemental molar ratio Si:Mg:Al:Bi:W=72.82:5.83:5.83:6.18:9.33) tungsten-bismuth composite oxide catalyst E is obtained.
[0059] Example 6
[0060] Application example of tungsten-bismuth composite oxide catalyst in the catalytic oxidation of 1,2-epoxycyclopentane to glutaraldehyde:
[0061] 0.2 g of the tungsten-bismuth composite oxide catalyst from the above examples and comparative examples was added to a 150 mL three-necked flask, along with 30 mL of tert-butanol as solvent. The mixture was stirred until homogeneous, and then 10 g of 1,2-epoxycyclopentane was added. At a reaction temperature of 35 °C, 8.9 g of 50% hydrogen peroxide was slowly added dropwise over a period of 120 min, maintaining the reaction temperature at 35 ± 3 °C during the addition. After the addition was complete, the reaction was continued at 35 °C for 6 h. The reaction results were confirmed by gas chromatography. The experimental results are shown in the table below:
[0062]
[0063] Example 7
[0064] Example of using tungsten-bismuth composite oxide catalysts for the catalytic oxidation of 1,2-epoxycyclopentane to glutaraldehyde: Effect of solvent
[0065] 0.15 g of the tungsten-bismuth composite oxide catalyst B from Example 2 was added to a 150 mL three-necked flask, along with 30 mL of solvent. The mixture was stirred until homogeneous, and then 10 g of 1,2-epoxycyclopentane was added. At a reaction temperature of 50 °C, 8.9 g of 50% hydrogen peroxide was slowly added dropwise over a period of 120 min, maintaining the reaction temperature at 50 ± 3 °C throughout the addition. After the addition was complete, the reaction was continued at 50 °C for 6 h. Gas chromatography was used to confirm the reaction results. The experimental results are shown in the table below:
[0066]
[0067] Example 8
[0068] Example of using tungsten-bismuth composite oxide catalyst for the catalytic oxidation of 1,2-epoxycyclopentane to glutaraldehyde: catalyst dosage
[0069] 0.25 g of the tungsten-bismuth composite oxide catalyst B from Example 2 was added to a 150 mL three-necked flask, followed by 30 mL of tert-butanol solvent. The mixture was stirred until homogeneous, then 10 g of 1,2-epoxycyclopentane was added. At a reaction temperature of 30 °C, 8.9 g of 50% hydrogen peroxide was slowly added dropwise over a period of 120 min, maintaining the reaction temperature at 30 ± 3 °C. After the addition was complete, the reaction was continued at 30 °C for 8 h. Gas chromatography was used to confirm the reaction results. The experimental results are shown in the table below:
[0070]
[0071] Example 9
[0072] Application example of tungsten-bismuth composite oxide catalyst for the catalytic oxidation of 1,2-epoxycyclopentane to glutaraldehyde: cyclic reaction
[0073] 0.25 g of the tungsten-bismuth composite oxide catalyst B from Example 2 was added to a 150 mL three-necked flask, followed by 40 mL of tert-butanol solvent. The mixture was stirred until homogeneous, and then 10 g of 1,2-epoxycyclopentane was added. At a reaction temperature of 40 °C, 8.9 g of 50% hydrogen peroxide was slowly added dropwise over a period of 120 min, maintaining the reaction temperature at 40 ± 3 °C. After the addition was complete, the reaction was continued at 40 °C for 8 h, and the reaction results were confirmed by gas chromatography.
[0074] Catalyst post-cycle treatment method: After the reaction, the reaction solution is cooled to room temperature, tungsten-bismuth composite oxide catalyst B is filtered, washed three times with 5 mL tert-butanol, dried under vacuum at 40 °C for 5 h, and directly used for the next cycle reaction.
[0075] The experimental results are shown in the table below:
[0076]
[0077] As can be seen from the table above, the catalyst can still maintain good catalytic activity after 10 cycles, and the corresponding yield of the catalyst is 88.5%, indicating that the catalyst of the present invention has good phase stability and can maintain high mechanical strength and chemical stability during long-term reaction.
Claims
1. A method for preparing a tungsten-bismuth composite oxide catalyst, characterized in that, Includes the following steps: (1) Mix the Al2O3 precursor and the aqueous solutions of SiO2 and MgO precursors with a dilute nitric acid solution containing bismuth nitrate. The mass concentration of bismuth nitrate is in the range of 10%-50%. Stir and mature at 0-80°C for 2-24 h to obtain a uniform colloidal solution. (2) Add the prepared sodium tungstate aqueous solution dropwise to the colloidal solution obtained in step (1), and continue to stir and age at 20-80 °C for 5-24 h. The resulting solid solution suspension is spray-dried at 200 °C-300 °C to obtain the catalyst precursor. The catalyst precursor is calcined by programmed heating or isothermal calcination at a temperature of 300 °C–750 °C for 2–20 h.
2. The preparation method according to claim 1, characterized in that, The catalyst precursor is calcined by programmed heating or isothermal roasting at a temperature of 400 °C - 650 °C for 2-8 h.
3. The preparation method according to claim 1, characterized in that, The precursor of SiO2 is selected from one or more of silica sol, 60-400 mesh column chromatography silica gel, and thin layer chromatography silica gel; the precursor of MgO is selected from one or more of magnesium nitrate, magnesium chloride, magnesium hydroxide, or magnesium oxide; the precursor of Al2O3 is selected from one or more of aluminum hydroxide, aluminum nitrate, or aluminum trichloride.
4. The preparation method according to claim 3, characterized in that, The precursor of SiO2 is selected from one or more of silica sol, 200-300 mesh column chromatography silica gel, and thin layer chromatography silica gel.
5. The method for preparing a tungsten-bismuth composite oxide catalyst according to claim 1, characterized in that, The amount of nitric acid added in step (1) should maintain the pH range of the colloidal solution obtained in step (1) as 0.1-3; the mass concentration of bismuth nitrate in the dilute nitric acid solution containing bismuth nitrate in step (1) is 10-50%; the amount of deionized water added in the system should meet the requirement that the mass fraction of solid content in the solid solution suspension obtained in step (2) is 5%-45%.
6. The preparation method according to claim 5, characterized in that, The amount of deionized water added to the system should meet the requirement that the mass fraction of solid content in the solid solution suspension obtained in step (2) is 10%-30%.
7. The preparation method according to claim 1, characterized in that, The tungsten-bismuth composite oxide catalyst is a silica-based composition containing silicon dioxide, magnesium oxide, aluminum oxide, bismuth oxide and tungsten oxide. Relative to the total molar amount of silicon, magnesium, aluminum, bismuth and tungsten, it contains 42-80 mol% silicon, 4-30 mol% magnesium, 5.5-28 mol% aluminum, 6-30 mol% bismuth and 4.5-35 mol% tungsten.
8. The preparation method according to claim 1, characterized in that, The spray drying temperature of the solid solution suspension is 200 ℃-300 ℃; the calcination atmosphere of the catalyst precursor is one or more of oxygen, air, nitrogen or argon atmosphere, and the heating method can be programmed heating or constant temperature, with the temperature between 300 ℃ and 750 °C and the calcination time between 2 and 20 h.
9. The preparation method according to claim 8, characterized in that, The spray drying temperature of the solid solution suspension is 250 °C-300 °C; the catalyst precursor is calcined in an air atmosphere; the heating method can be programmed heating or constant temperature, with a temperature of 400 °C-650 °C; the calcination time is 2-8 h.
10. A tungsten-bismuth composite oxide catalyst prepared by any one of the preparation methods according to claims 1-8.
11. The application of the tungsten-bismuth composite oxide catalyst of claim 10 in the catalytic oxidation of 1,2-epoxycyclopentane to glutaraldehyde.
12. The application according to claim 11, characterized in that, The tungsten-bismuth composite oxide catalyst is used for the catalytic oxidation of 1,2-epoxycyclopentane to prepare glutaraldehyde, comprising the following steps: mixing the tungsten-bismuth composite oxide catalyst with a reaction solvent, adding 1,2-epoxycyclopentane, adding hydrogen peroxide solution, and preparing glutaraldehyde through a catalytic oxidation reaction.
13. The application according to claim 11 or 12, characterized in that: The amount of the tungsten-bismuth composite oxide catalyst added is 1-10% of the mass of 1,2-epoxycyclopentane; the molar ratio of hydrogen peroxide to 1,2-epoxycyclopentane is 1-1.5; and the volume-to-mass ratio of the solvent to 1,2-epoxycyclopentane is 1.5-8:1 (mL:g).
14. The application according to claim 13, characterized in that: The amount of the tungsten-bismuth composite oxide catalyst added is 1-5% of the mass of 1,2-epoxycyclopentane; the molar ratio of hydrogen peroxide to 1,2-epoxycyclopentane is 1.1-1.3; and the volume-to-mass ratio of the solvent to 1,2-epoxycyclopentane is 2-4:1 (mL:g).
15. The application according to claim 12, characterized in that, The reaction temperature is 25 ℃-80 ℃; the reaction time is 2-12 hours; the reaction solvent is one or more of isopropanol, tert-amyl alcohol, tert-butanol, ethylene glycol monomethyl ether, and ethylene glycol.
16. The application according to claim 15, characterized in that, The reaction temperature is 25 ℃-50 ℃; the reaction time is 2-6 hours.