A transition metal tungstate catalyst and a method for synthesizing valerolactam using the same
The synthesis process of valproamide was simplified by using a transition metal tungstate catalyst supported on activated carbon, which solved the complexity and pollution problems of the existing technology and enabled efficient and economical production of valproamide.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- PUYANG HONGYE ENVIRONMENTAL TECH RES INST CO LTD
- Filing Date
- 2024-03-14
- Publication Date
- 2026-06-09
AI Technical Summary
Existing methods for synthesizing valproic acid have problems such as cumbersome and complex operation steps, harsh reaction conditions, generation of environmentally polluting byproducts, poor reusability of catalysts, and unsatisfactory conversion and selectivity.
A novel process route for the one-step synthesis of valeramide from cyclopentanone was constructed by uniformly mixing the transition metal tungstate, support, and solvent, followed by impregnation at room temperature, drying, and pulverization, and then using the catalyst supported on activated carbon for the ammoximation and Beckmann rearrangement of cyclopentanone.
The process was simplified, production costs were reduced, atom utilization and product yield were improved, wastewater treatment difficulty was reduced, and the catalyst had good reusability.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalytic chemical technology, specifically relating to a transition metal tungstate catalyst and a method for synthesizing valerate using the same. Background Technology
[0002] Valerolamide is a widely used chemical product and an important organic chemical raw material. It can be polymerized and further processed to produce plastics, fibers, and films, showing great application potential in the production of synthetic fibers and plastics.
[0003] Currently, methods for synthesizing valproamide include the Beckmann rearrangement, piperidine oxidation, 1-amino acid cyclization, and lactone amination. Among these methods, the Beckmann rearrangement is the main method for synthesizing lactam and is currently the industrial production method for valproamide. Approximately 90% of the world's valproamide is prepared from cyclopentanone oxime via the Beckmann rearrangement. Compared to the Beckmann rearrangement method, the other methods often suffer from drawbacks such as the use of complex and expensive precious metal catalysts, the high cost and scarcity of starting materials, and the harsh and unsafe production conditions.
[0004] Taking the preparation of valproic acid as an example, the Beckmann rearrangement process is as follows: fuming sulfuric acid is used to form valproic acid sulfate from cyclopentanone oxime. In this process, excess fuming sulfuric acid needs to be added to obtain a high yield of valproic acid. Then, the mixture is neutralized with ammonia water to obtain valproic acid and ammonium sulfate. At present, there is a lack of research on industrial large-scale production methods for valproic acid, and the existing valproic acid synthesis methods also have the following practical production problems: (1) the oxime content in the cyclopentanone oxime ammonification wastewater is high, and the oxime loss is high; (2) the Beckmann rearrangement of cyclopentanone oxime has poor selectivity, high consumption of fuming sulfuric acid, and large ammonium sulfate yield; (3) it is difficult to extract benzene solution from the neutralized valproic acid oil. Therefore, the industry urgently needs to develop an industrial production method for valproic acid that is simple, mild, economical and low-cost. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a transition metal tungstate catalyst and a method for synthesizing valeramide using the same. The synthesis of valeramide using this catalyst has advantages such as simple process, mild conditions, greater economy, and low cost, solving the technical problems of existing industrial valeramide production methods, including cumbersome and complex operating steps, harsh reaction conditions, easy generation of environmentally polluting byproducts during the reaction, and poor catalyst reusability.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A method for preparing a transition metal tungstate catalyst, comprising the following steps:
[0008] The transition metal tungstate, the pretreated carrier, and the solvent are thoroughly mixed and then allowed to stand at room temperature for 8-24 hours. After drying and pulverizing, the product is obtained.
[0009] In this invention, the transition metal is a transition metal from the fourth period of the periodic table, preferably iron, cobalt, nickel, copper, etc., and more preferably cobalt. Specifically, the transition metal tungstate is one or more of FeWO4, CoWO4, NiWO4, and CuWO4, and more preferably CoWO4.
[0010] Furthermore, the carrier is activated carbon, which undergoes pretreatment before use. The mass ratio of the transition metal tungstate to the carrier is 1:2-4. In this invention, the activated carbon is black granular fruit shell activated carbon, preferably made from high-quality and environmentally friendly coconut shells, peach shells, walnut shells, jujube shells, etc., and more preferably coconut shell activated carbon.
[0011] Specifically, the solvent can be one of cyclohexane, ethanol, distilled water, or acetonitrile. The amount of solvent added should be sufficient to submerge the transition metal tungstate and the support. Mixing can be performed by ultrasonic vibration for 10-40 minutes.
[0012] Specifically, the pretreatment can be one of vacuum drying, forced air drying, mechanical grinding, etc.
[0013] Furthermore, during drying and pulverizing, the product can be dried in an oven or blower dryer at 70-100℃ for 4-12 hours before grinding and pulverizing.
[0014] More preferably, the transition metal tungstate is a transition metal tungstate modified with sodium citrate (C6H5Na3O7·2H2O). It is prepared by the following steps:
[0015] Mix C6H5Na3O7·2H2O aqueous solution and M(NH4)2·(SO4)2·6H2O aqueous solution, then add Na2WO4·2H2O aqueous solution and mix evenly. Then react at 423K-523K for 8-16 hours, cool, separate solid and liquid, and then wash, dry and pulverize to obtain the product.
[0016] M is Fe, Co, Ni or Cu; the molar ratio of C6H5Na3O7·2H2O, M(NH4)2·(SO4)2·6H2O and Na2WO4·2H2O is 1-2:1-2:1.
[0017] This invention provides a transition metal tungstate catalyst prepared by the above-described preparation method.
[0018] This invention provides the application of the above-mentioned transition metal tungstate catalyst in the catalytic synthesis of valproamide.
[0019] This invention provides a method for synthesizing valproamide using the aforementioned transition metal tungstate catalyst, wherein cyclopentanone, the transition metal tungstate catalyst, NH3·H2O and hydrogen peroxide are mixed and reacted at 45-55°C for 4-6 h.
[0020] In this invention, the reaction steps such as the ammonium oxime reaction and the Beckmann rearrangement reaction can all be achieved using existing methods.
[0021] This invention synthesizes a series of activated carbon-supported transition metal tungstate catalysts and investigates their catalytic performance in the cyclopentanone ammoniation and cyclopentanone oxime Beckmann rearrangement reactions. The two-step reactions of cyclopentanone ammoniation and cyclopentanone oxime Beckmann rearrangement are studied in the same reactor, constructing a new one-step process route for the synthesis of valeramide from cyclopentanone. The innovation of this invention lies in the synthesis of a series of activated carbon-supported transition metal tungstate catalysts, thereby constructing a new one-step process route for the synthesis of valeramide from cyclopentanone based on these catalysts. This overcomes the technical shortcomings of existing industrial valeramide production methods, such as cumbersome and complex operation steps, harsh reaction conditions, easy generation of environmentally polluting byproducts during the reaction, poor catalyst reusability, unsatisfactory conversion rate of the valeramide oxime reaction, low atom utilization rate, and low extraction rates of product oil and synthesis wastewater.
[0022] Compared with the prior art, the present invention has the following beneficial effects:
[0023] The activated carbon-supported transition metal tungstate catalyst of the present invention is obtained by uniformly mixing transition metal tungstate, support and solvent, impregnating at room temperature, drying and pulverizing. It has the characteristics of simple process, mild conditions and low cost.
[0024] This invention reveals that using the aforementioned supported transition metal tungstate catalyst for the oxime and rearrangement of cyclopentanone helps improve atom utilization and reduce the oxime content in the production wastewater; it also helps reduce the acid-oxime ratio in the rearrangement, eliminates ammonium sulfate production, improves product yield, reduces wastewater treatment difficulty, and is suitable for industrial-scale production. When the aforementioned transition metal tungstate catalyst is used to synthesize valeramide, the conversion rate of cyclopentanone can reach up to 98%, and the selectivity of the valeramide product can reach 91%. Attached Figure Description
[0025] Figure 1 This is a graph showing the repeatability stability data of the cobalt tungstate catalyst. Detailed Implementation
[0026] The technical solution of the present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto.
[0027] In the following embodiments, unless otherwise specified, all raw materials used are commercially available products or can be prepared using conventional methods in the art.
[0028] In this embodiment, coconut shell activated carbon was selected. Room temperature refers to 25±5℃. m refers to the mass ratio. n refers to the molar ratio.
[0029] When synthesizing valproic acid, the concentration of ammonia (NH3·H2O) used is 25%~28%, and the concentration of hydrogen peroxide is 27.5%~32.5%, both referring to mass percentage concentrations.
[0030] Example 1
[0031] The preparation method of activated carbon-supported iron tungstate catalyst (FeWO4 / C) includes the following steps:
[0032] (1) Carrier pretreatment: Place the activated carbon in a blower dryer and dry it at 70°C for 5 hours;
[0033] (2) Preparation of iron tungstate: Weigh 0.02 mol of C6H5Na3O7·2H2O, Fe(NH4)2·(SO4)2·6H2O and Na2WO4·2H2O (molar ratio 1:1:1) and dissolve them in 40 mL of deionized water to obtain aqueous solutions with a concentration of 0.5 mol / L. Place the 0.5 mol / L C6H5Na3O7·2H2O aqueous solution and the 0.5 mol / L Fe(NH4)2·(SO4)2·6H2O aqueous solution in a 500 mL Erlenmeyer flask and mix them evenly. Then pour in the 0.5 mol / L Na2WO4·2H2O aqueous solution and stir evenly. Then pour the mixture into a 200 mL reaction vessel with a polytetrafluoroethylene liner and place it in a digital display drying oven at a constant temperature of 473 K for 12 hours. After the reaction was completed, the reaction vessel was cooled to room temperature, the product was taken out, filtered and washed to obtain a solid product, and then placed in a vacuum drying oven at 353 K for 3 hours to dry. The dried product was then ground and pulverized with an agate mortar to finally obtain FeWO4 particles modified with sodium citrate.
[0034] (3) Mixing: Add 1g of FeWO4 modified with sodium citrate in step (2), 2g of activated carbon dried in step (1), and 10mL of distilled water to a beaker, place it in an ultrasonic cleaner and ultrasonically stir and mix at 40℃ for 15min until it is fully mixed and a gel-like substance is obtained.
[0035] (4) Impregnation: Let the gelatinous substance from step (3) stand at room temperature for 12 hours to impregnate;
[0036] (5) Drying: Place the gelatinous material after soaking for 12 hours into a blower dryer and dry it at 70°C for 5 hours.
[0037] (6) Grinding: The solid obtained after drying in step (5) is thoroughly ground and pulverized. The resulting solid powder is the iron tungstate catalyst supported on activated carbon, denoted as FeWO4 / C.
[0038] The synthesis of valeramide from cyclopentanone was carried out in a 250 mL three-necked reactor under constant temperature water bath, magnetic stirring, and a low-temperature circulating reflux condenser. Under optimized conditions of solvent-free reaction, 0.01 mol cyclopentanone, m(FeWO4 / C) / m(cyclopentanone) = 0.005, n(NH3·H2O) / n(cyclopentanone) = 4, n(hydrogen peroxide) / n(cyclopentanone) = 2, reaction temperature of 50℃, and reaction time of 5 h, the conversion rate of cyclopentanone was 67.8%, and the selectivity of the product valeramide was 56.0%.
[0039] Example 2
[0040] The preparation method of activated carbon-supported cobalt tungstate catalyst (CoWO4 / C) includes the following steps:
[0041] (1) Carrier pretreatment: Place the activated carbon in a blower dryer and dry it at 70°C for 5 hours;
[0042] (2) Preparation of cobalt tungstate: Weigh 0.02 mol of C6H5Na3O7·2H2O, Co(NH4)2·(SO4)2·6H2O and Na2WO4·2H2O (molar ratio 1:1:1) and dissolve them in 40 mL of deionized water to obtain aqueous solutions with a concentration of 0.5 mol / L. Place the 0.5 mol / L C6H5Na3O7·2H2O aqueous solution and the 0.5 mol / L Co(NH4)2·(SO4)2·6H2O aqueous solution in a 500 mL Erlenmeyer flask and mix them evenly. Then pour in the 0.5 mol / L Na2WO4·2H2O aqueous solution and stir evenly. Then pour the mixture into a 200 mL reaction vessel with a polytetrafluoroethylene liner and place it in a digital display drying oven at a constant temperature of 473 K for 12 hours. After the reaction was completed, the reaction vessel was cooled to room temperature, the product was taken out, filtered and washed to obtain a solid product, and then placed in a vacuum drying oven at 353 K for 3 hours to dry. The dried product was then ground and pulverized with an agate mortar to finally obtain sodium citrate modified CoWO4 particles.
[0043] (3) Mixing: Add 1g of CoWO4 modified with sodium citrate in step (2), 2g of activated carbon dried in step (1), and 10mL of distilled water to a beaker, place it in an ultrasonic cleaner and ultrasonically stir and mix at 40℃ for 25min until it is fully mixed and a gel-like substance is obtained.
[0044] (4) Impregnation: Let the gelatinous substance from step (3) stand at room temperature for 12 hours to impregnate;
[0045] (5) Drying: Place the gelatinous material after soaking for 12 hours into a blower dryer and dry it at 80°C for 5 hours.
[0046] (6) Grinding: The solid obtained after drying in step (5) is thoroughly ground and pulverized. The resulting solid powder is the cobalt tungstate catalyst supported on activated carbon, denoted as CoWO4 / C.
[0047] The synthesis of valeramide from cyclopentanone was carried out in a 250 mL three-necked reactor under constant temperature water bath, magnetic stirring, and a low-temperature circulating reflux condenser. Under optimized conditions of solvent-free reaction, 0.01 mol cyclopentanone, m(CoWO4 / C) / m(cyclopentanone) = 0.005, n(NH3·H2O) / n(cyclopentanone) = 4, n(hydrogen peroxide) / n(cyclopentanone) = 2, reaction temperature of 50 °C, and reaction time of 5 h, the conversion rate of cyclopentanone was 98%, and the selectivity for the product valeramide was 91%.
[0048] Example 3
[0049] The preparation method of activated carbon-supported nickel tungstate catalyst (NiWO4 / C) includes the following steps:
[0050] (1) Carrier pretreatment: Place the activated carbon in a blower dryer and dry it at 75°C for 5 hours;
[0051] (2) Preparation of nickel tungstate: Weigh 0.02 mol of C6H5Na3O7·2H2O, Ni(NH4)2·(SO4)2·6H2O and Na2WO4·2H2O (molar ratio 1:1:1) and dissolve them in 40 mL of deionized water to obtain aqueous solutions with a concentration of 0.5 mol / L. Place the 0.5 mol / L C6H5Na3O7·2H2O aqueous solution and the 0.5 mol / L Ni(NH4)2·(SO4)2·6H2O aqueous solution in a 500 mL Erlenmeyer flask and mix them evenly. Then pour in the 0.5 mol / L Na2WO4·2H2O aqueous solution and stir evenly. Then pour the mixture into a 200 mL reaction vessel with a polytetrafluoroethylene liner and place it in a digital display drying oven at a constant temperature of 473 K for 12 hours. After the reaction was completed, the reaction vessel was cooled to room temperature, the product was taken out, filtered and washed to obtain a solid product, and then placed in a vacuum drying oven at 353 K for 3 hours to dry. The dried product was then ground and pulverized with an agate mortar to finally obtain NiWO4 particles modified with sodium citrate.
[0052] (3) Mixing: Add 1g of NiWO4 modified with sodium citrate in step (2), 2g of activated carbon dried in step (1), and 10mL of distilled water to a beaker, place it in an ultrasonic cleaner and ultrasonically stir and mix at 40℃ for 15min until it is fully mixed and a gel-like substance is obtained.
[0053] (4) Impregnation: Let the gelatinous substance from step (3) stand at room temperature for 12 hours to impregnate;
[0054] (5) Drying: Place the gelatinous material after soaking for 12 hours into a blower dryer and dry it at 70°C for 5 hours.
[0055] (6) Grinding: The solid obtained after drying in step (5) is thoroughly ground and pulverized. The resulting solid powder is the nickel tungstate catalyst supported on activated carbon, denoted as NiWO4 / C.
[0056] The synthesis of valeramide from cyclopentanone was carried out in a 250 mL three-necked reactor under constant temperature water bath, magnetic stirring, and a low-temperature circulating reflux condenser. Under optimized conditions of solvent-free reaction, 0.01 mol cyclopentanone, m(NiWO4 / C) / m(cyclopentanone) = 0.005, n(NH3·H2O) / n(cyclopentanone) = 4, n(hydrogen peroxide) / n(cyclopentanone) = 2, reaction temperature of 50℃, and reaction time of 5 h, the conversion rate of cyclopentanone was 75.2%, and the selectivity of the product valeramide was 66.7%.
[0057] Example 4
[0058] The preparation method of activated carbon-supported copper tungstate catalyst (CuWO4 / C) includes the following steps:
[0059] (1) Carrier pretreatment: Place the activated carbon in a blower dryer and dry it at 75°C for 5 hours;
[0060] (2) Preparation of copper tungstate: Weigh 0.02 mol of C6H5Na3O7·2H2O, Cu(NH4)2·(SO4)2·6H2O and Na2WO4·2H2O (molar ratio 1:1:1) and dissolve them in 40 mL of deionized water to obtain aqueous solutions with a concentration of 0.5 mol / L. Place the 0.5 mol / L C6H5Na3O7·2H2O aqueous solution and the 0.5 mol / L Cu(NH4)2·(SO4)2·6H2O aqueous solution in a 500 mL Erlenmeyer flask and mix them evenly. Then pour in the 0.5 mol / L Na2WO4·2H2O aqueous solution and stir evenly. Then pour the mixture into a 200 mL reaction vessel with a polytetrafluoroethylene liner and place it in a digital display drying oven at a constant temperature of 473 K for 12 hours. After the reaction was completed, the reaction vessel was cooled to room temperature, the product was taken out, filtered and washed to obtain a solid product, and then placed in a vacuum drying oven at 353 K for 3 hours to dry. The dried product was then ground and pulverized with an agate mortar to finally obtain CuWO4 particles modified with sodium citrate.
[0061] (3) Mixing: Add 1g of CuWO4 modified with sodium citrate in step (2), 2g of activated carbon dried in step (1), and 10mL of distilled water to a beaker, place it in an ultrasonic cleaner and ultrasonically stir and mix at 40℃ for 15min until it is fully mixed and a gel-like substance is obtained.
[0062] (4) Impregnation: Let the gelatinous substance from step (3) stand at room temperature for 18 hours to impregnate;
[0063] (5) Drying: Place the gelatinous material after soaking for 12 hours into a blower dryer and dry it at 70°C for 5 hours.
[0064] (6) Grinding: The solid obtained after drying in step (5) is thoroughly ground and pulverized. The resulting solid powder is the copper tungstate catalyst supported on activated carbon, denoted as CuWO4 / C.
[0065] The synthesis of valeramide from cyclopentanone was carried out in a 250 mL three-necked reactor under constant temperature water bath, magnetic stirring, and a low-temperature circulating reflux condenser. Under optimized conditions of solvent-free reaction, 0.01 mol cyclopentanone, m(CuWO4 / C) / m(cyclopentanone) = 0.005, n(NH3·H2O) / n(cyclopentanone) = 4, n(hydrogen peroxide) / n(cyclopentanone) = 2, reaction temperature of 50℃, and reaction time of 5 h, the conversion rate of cyclopentanone was 53.8%, and the selectivity of the product valeramide was 46.9%.
[0066] Example 5
[0067] The reuse of catalysts is of great significance for industrial production. Taking advantage of the solid nature of catalysts, after the reaction is complete, the catalyst can be recovered and reused by centrifuging, washing with acetonitrile, and drying.
[0068] The verification was carried out using a cobalt tungstate catalyst supported on activated carbon (CoWO4 / C) as an example.
[0069] The reusability of the catalyst was investigated under the following feeding conditions: no solvent, 0.01 mol of cyclopentanone, m(CoWO4 / C) / m(cyclopentanone) = 0.005, n(NH3·H2O) / n(cyclopentanone) = 4, n(hydrogen peroxide) / n(cyclopentanone) = 2, reaction temperature 50℃, and reaction time 5 h. The results are as follows: Figure 1 As shown.
[0070] Figure 1 The experimental results show that during the repeated use of the activated carbon-supported cobalt tungstate catalyst CoWO4 / C, the conversion rate of cyclopentanone remained above 91%, and the selectivity of valeramide remained above 84%. The catalyst maintained relatively stable catalytic activity in five consecutive cycles, indicating that the catalyst (CoWO4 / C) has good reusability.
[0071] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.
Claims
1. The application of a transition metal tungstate catalyst in the catalytic synthesis of valeramide from cyclopentanone, characterized in that, The transition metal tungstate catalyst was prepared via the following steps: The transition metal tungstate, the pretreated carrier, and the solvent are mixed evenly, then allowed to stand at room temperature for 8-24 hours for impregnation, and then dried and pulverized to obtain the final product. The transition metal tungstate is one or more of FeWO4, CoWO4, NiWO4, and CuWO4.
2. The application of the transition metal tungstate catalyst as described in claim 1 in the catalytic synthesis of valeramide from cyclopentanone, characterized in that, The carrier is activated carbon, and the mass ratio of the transition metal tungstate to the activated carbon is 1:2-4.
3. The application of the transition metal tungstate catalyst as described in claim 1 in the catalytic synthesis of valeramide from cyclopentanone, characterized in that, The solvent is cyclohexane, ethanol, distilled water, or acetonitrile.
4. The application of the transition metal tungstate catalyst as described in claim 1 in the catalytic synthesis of valeramide from cyclopentanone, characterized in that, The pretreatment is one of vacuum drying, forced air drying, or mechanical grinding.
5. The application of the transition metal tungstate catalyst as described in claim 1 in the catalytic synthesis of valproic acid from cyclopentanone, characterized in that, The drying process involves drying at 70-100℃ for 4-12 hours.
6. The application of the transition metal tungstate catalyst as described in claim 2 in the catalytic synthesis of valeramide from cyclopentanone, characterized in that, The transition metal tungstate is a sodium citrate-modified transition metal tungstate; it is prepared by the following steps: Mix C6H5Na3O7·2H2O aqueous solution and M(NH4)2·(SO4)2·6H2O aqueous solution, then add Na2WO4·2H2O aqueous solution and mix evenly. Then react at 423K-523K for 8-16 hours, cool, separate solid and liquid, and then wash, dry and pulverize to obtain the product. M is Fe, Co, Ni or Cu; the molar ratio of C6H5Na3O7·2H2O, M(NH4)2·(SO4)2·6H2O and Na2WO4·2H2O is 1-2:1-2:
1.
7. A method for synthesizing valproic acid, characterized in that, Cyclopentanone, the transition metal tungstate catalyst prepared in claim 1, NH3·H2O and hydrogen peroxide were mixed and reacted at 45-55℃ for 4-6 h.