Halogen-free alkaline earth metal-based catalyst and application thereof in carboxylation reaction
By using halogen-free alkaline earth metal-based catalysts, the problem of halogen-containing catalysts in the prior art is solved, and efficient carboxylation reaction is achieved, reducing operating costs.
Patent Information
- Application Number
- CN202411500399.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-25
- Publication Date
- 2025-02-14
AI Technical Summary
In the prior art, the catalysts used in the carboxylation reaction usually contain halogen, resulting in inconvenience in the environment, equipment and separation process and increasing the investment in the equipment.
A halogen-free alkaline earth metal-based catalyst is provided, which includes calcium, magnesium alkaline earth metal oxide, aluminum salt and silver salt, which is used in carboxylation reactions and is prepared by co-precipitation method to avoid the use of halogen.
The catalyst exhibits high efficiency activity in the carboxylation reaction, with a conversion rate of propylene oxide higher than 99%, and a yield of propylene carbonate higher than 70%, while reducing the operating cost of subsequent purification.
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of catalysts, and in particular relates to a halogen-free alkaline earth metal-based catalyst and application thereof in carboxylation reactions. Background Art
[0002] Converting CO2 into more value-added energy, chemical raw materials and fine chemicals through chemical methods has become a hot topic in current scientific work and has attracted attention from many aspects. Carboxylation reaction is an effective method for fixing CO2. The carbonylation synthesis reaction of carbonate derivatives conforms to the concept of green chemistry. Propylene carbonate has developed rapidly because it can be used as an excellent medium for high-energy batteries and capacitors. It is an important chemical product for the high-value recycling of CO2.
[0003] Up to now, the main reported methods for the synthesis of propylene carbonate are: phosgene method, urea alcoholysis method, propylene oxide carboxylation method, etc. Phosgene is a highly toxic chemical, and this route also produces a large amount of chloride as a by-product, which causes serious corrosion to equipment. The urea method needs further research and development due to its thermodynamic limitations in low-temperature synthesis and high energy consumption at high temperatures. The propylene oxide route has become the mainstream production method in China. Carboxylation catalysts can be divided into homogeneous catalysts and heterogeneous catalysts according to their different states in the reaction system. Homogeneous catalysts include metal complex families, metal halide families, non-metallic organic catalyst families, and ionic liquid catalyst families. Heterogeneous catalysts mainly refer to resins, metal oxides, and homogeneous solid-supported catalysts that have both Lewis acid and alkaline active sites.
[0004] Whether it is the industrialized catalyst or the ionic liquid catalytic system that is a hot research and development topic, they basically contain halogens, which is unfriendly to the environment, equipment, separation and application, and also increases the investment in equipment. Therefore, further research and development is needed. Summary of the invention
[0005] The purpose of the present invention is to provide a halogen-free alkaline earth metal-based catalyst in response to the technical problems existing in the prior art. The catalyst is a halogen-free metal oxide heterogeneous catalytic system, which can be used in a plug flow reactor and a fully mixed flow reactor. Since the catalytic system does not contain halogen, the operating cost of subsequent purification is reduced.
[0006] In order to achieve the purpose of the present invention, the specific technical scheme of the present invention is as follows:
[0007] A halogen-free alkaline earth metal-based catalyst comprises a first component, a second component and a third component; calcium and magnesium alkaline earth metal oxides are used as the first component, accounting for 60%-90% of the total mass of the catalyst, and the molar ratio of magnesium to calcium is 3-6:1; aluminum salt is used as the second component, accounting for 10%-40% of the total mass; silver salt is used as the third component, accounting for 0.01%-0.5% of the total mass, and the sum of the total mass percentages is 100%.
[0008] The above-mentioned halogen-free alkaline earth metal-based catalyst is used in the carboxylation reaction. When used, dimethylformamide (DMF) needs to be introduced as a solvent, and the amount of the solvent added is 1-10 times the mass of the catalyst.
[0009] The preparation method of the above-mentioned halogen-free alkaline earth metal-based catalyst comprises the following steps:
[0010] (1) Weighing the active component in proportion, and then preparing the active component into an aqueous solution with a mass fraction of 15%-17%; and preparing a precipitant aqueous solution at the same time, the concentration of the precipitant aqueous solution is equal to the concentration of the active component aqueous solution (i.e., also 15wt%-17wt%);
[0011] (2) adding the active component aqueous solution and the precipitant aqueous solution into the precipitation kettle at a prescribed rate, stirring while adding; after the addition is completed, when the solution temperature reaches 98±2°C, the oil bath temperature is lowered to 102±2°C, stirring is maintained for 1 hour, and then allowed to stand for more than 5 hours;
[0012] (3) cooling and filtering the substance finally obtained in (2) to obtain a white solid;
[0013] (4) The white solid obtained in (3) was washed three times with deionized water and then dried at 120±2°C to constant weight;
[0014] (5) The material finally obtained in (4) is immersed in an aqueous solution containing silver nitrate for 5-10 hours in equal volume, and then dried to constant weight and calcined to obtain the catalyst.
[0015] Furthermore, in the preparation method of the halogen-free alkaline earth metal-based catalyst, the active component is selected from its nitrate or chloride; and the precipitant is urea.
[0016] Furthermore, in the preparation method of the halogen-free alkaline earth metal-based catalyst, in order to fully dissolve the active component and the precipitant, they are heated to 90±2° C. during dissolution.
[0017] Furthermore, in the method for preparing the halogen-free alkaline earth metal-based catalyst, the rate in step (2) is 8-10 mL / s.
[0018] Furthermore, in the preparation method of the halogen-free alkaline earth metal-based catalyst, the drying temperature in step (5) is 120±2° C.; the calcination temperature is 800±50° C., and the time is 1 hour.
[0019] Furthermore, in the method for preparing the halogen-free alkaline earth metal-based catalyst, the catalyst obtained in step (5) is a powder, which can be used after being pressed into tablets.
[0020] Furthermore, when the halogen-free alkaline earth metal-based catalyst prepared by any of the above methods is used for the carboxylation reaction of propylene oxide, in a fully mixed flow reactor, the carbon dioxide pressure is 1-5MPa, the temperature is 130-150°C, the reaction time is 3-5 hours, the propylene oxide conversion rate is >99%, and the yield of propylene carbonate is >70%; based on propylene carbonate, the catalytic activity (space-time yield) is >11g / h·gcat.
[0021] Furthermore, the halogen-free alkaline earth metal-based catalyst prepared by any of the above methods, when the catalyst undergoes propylene oxide carboxylation reaction in a plug flow reactor, the carbon dioxide pressure is 1-5MPa, the temperature is 130-150°C, the residence time is 50-70 minutes, the propylene oxide conversion rate is >99%, and the propylene carbonate yield is >65%; based on propylene carbonate, the catalytic activity (space-time yield) is >40g / h·gcat.
[0022] Compared with the prior art, the present invention has the following beneficial effects:
[0023] (1) The catalyst uses cheaper and more readily available alkaline earth metals as the main component, which is lower in cost than ionic liquid catalysts and is more conducive to replacing traditional iodide catalysts;
[0024] (ii) The catalytic system does not contain halogen, which reduces the operating cost of subsequent purification;
[0025] (III) In this scheme, although DMF is used as a solvent, the boiling points of DMF and propylene carbonate are quite different and are easy to separate. DMF can be used as an additive to battery fluid, and trace amounts of residues have little effect on the battery fluid.
[0026] (iv) Heterogeneous catalysts reduce the difficulty of separating catalysts from products and can be used in different reactors for different working conditions. DETAILED DESCRIPTION
[0027] An application of a halogen-free alkaline earth metal-based catalyst in a carboxylation reaction, the method comprising the following steps:
[0028] The catalytic system comprises an active component (catalyst) and a solvent, wherein the active component uses calcium and magnesium alkaline earth metal oxides as the first component, accounting for 60%-90% of the total mass of the catalyst, and the molar ratio of magnesium to calcium is 3-6:1; aluminum salt is the second component, accounting for 10%-40% of the total mass; and silver salt is the third component, accounting for 0.01%-0.5% of the total mass. The catalyst is used in the carboxylation reaction process, and dimethylformamide (DMF) is introduced as a solvent, and the added mass is 1-10 times that of the catalyst.
[0029] Furthermore, the halogen-free alkaline earth metal-based catalyst is prepared by a coprecipitation method. The metal salts of calcium, magnesium and aluminum are preferably nitrates, and chlorides are secondarily selected, and are prepared into an aqueous solution with a mass fraction of 15%-17%. Urea is selected as the precipitant and prepared into an aqueous solution of the same concentration. After being fully dissolved at 90°C, the two groups of aqueous solutions are added to the precipitation kettle (110°C oil bath) at a rate of 8-10mL / s in the same proportion while stirring. After the addition is completed, after the solution temperature reaches 98±2°C, the oil bath temperature is reduced to 102±2°C, and after stirring for 1-1.5 hours, it is allowed to stand for more than 5 hours. Cool down and filter to obtain a white solid. After washing with deionized water 3 times, it is dried at 120±2°C to constant weight. Then, an equal volume of silver nitrate aqueous solution is impregnated for 5-10h, and after being dried at 120±2°C to constant weight, it is calcined at 800±50°C for 1 hour to obtain a catalyst powder. It can be used directly according to the process, or it can be used after tableting.
[0030] The halogen-free alkaline earth metal-based catalyst is used as an example reaction for the carboxylation of propylene oxide. In a fully mixed flow reactor, the carbon dioxide pressure is 1-5 MPa, the temperature is 130-150° C., the reaction time is 3-5 hours, the propylene oxide conversion rate is >99%, and the yield of propylene carbonate is >70%. Based on propylene carbonate, the catalytic activity (space-time yield) is >11 g / h·gcat.
[0031] The halogen-free alkaline earth metal-based catalyst, when undergoing propylene oxide carboxylation reaction in a plug flow reactor, has a carbon dioxide pressure of 1-5 MPa, a temperature of 130-150° C., a residence time of 50-70 minutes, a propylene oxide conversion rate of >99%, and a propylene carbonate yield of >65%. The catalytic activity (space-time yield) is >40 g / h·gcat based on propylene carbonate.
[0032] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.
[0033] Any feature disclosed in this specification (including claims and abstract), unless otherwise stated, may be replaced by other equivalent or alternative features having similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.
[0034] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.
[0035] Embodiment 1:
[0036] Preparation of Catalyst A:
[0037] Magnesium nitrate hexahydrate, calcium nitrate, and anhydrous aluminum nitrate were prepared into a metal salt aqueous solution with a mass fraction of 15% in a molar ratio of 5:1:1.7. The amount of urea used as a precipitant was higher than the theoretical amount, and the metal salt aqueous solution was prepared into an equal volume solution of the same concentration. Then, the metal salt aqueous solution and the precipitant aqueous solution were fully dissolved at 90°C, and the two groups of aqueous solutions were added to the precipitation kettle (110°C oil bath, stirring and adding) at the same speed of 10mL / s for equal volume co-precipitation. After the addition was completed, when the solution temperature reached 98°C, the oil bath temperature was reduced to 102°C, and stirring was maintained for 1 hour. After standing for 5 hours, it was filtered to room temperature to obtain a white solid. The white solid was washed 3 times with deionized water, filtered and dried at 120°C to constant weight. Then, a silver nitrate solution was added and immersed in equal volumes at room temperature for 5 hours. Among them, the molar ratio of silver nitrate to calcium nitrate is 0.006:1. After soaking, the mixture was dried at 120°C to constant weight, and then calcined at 800°C for 1 hour to obtain catalyst powder, which was then formed into catalyst A.
[0038] Embodiment 2:
[0039] Preparation of Catalyst B
[0040] Magnesium chloride hexahydrate, calcium chloride hexahydrate, and aluminum nitrate hexahydrate are prepared into a metal salt aqueous solution with a mass fraction of 16% in a molar ratio of 6:1:1. The amount of urea used as a precipitant is much higher than the theoretical value, and the metal salt solution is prepared into an equal volume solution with the same concentration. The remaining steps are the same as in Example 1 to prepare catalyst B. The molar ratio of silver nitrate to calcium nitrate is 0.01:1.
[0041] Embodiment 3:
[0042] Catalyst A (prepared in Example 1) was used in a tank reactor for the carboxylation reaction of propylene oxide with carbon dioxide.
[0043] In a 1L stainless steel reactor, 500g of propylene oxide, 50g of DMF, 10g of catalyst A, 3MPa of carbon dioxide, temperature 140±2°C, reaction time 4 hours, propylene oxide in the product is below the GC detection line, propylene carbonate 630g.
[0044] Embodiment 4:
[0045] Catalyst B (prepared in Example 2) was used for the carboxylation reaction of propylene oxide with carbon dioxide in a fixed bed reactor.
[0046] In a fixed bed reactor, 18 g of catalyst A, 3.5 MPa of carbon dioxide, a hot spot temperature of 145 ± 2 ° C, propylene oxide and DMF were prepared in a mass ratio of 10:1, 200 g was fed per hour, and the product contained an average of 220 g of propylene carbonate per hour, and the propylene oxide in the product was below the GC detection line.
[0047] Comparative Example 1:
[0048] Catalyst C preparation:
[0049] Magnesium nitrate hexahydrate, calcium nitrate and anhydrous aluminum nitrate were prepared in a molar ratio of 3:3:1.7 in the same manner as in Example 1, and catalyst C was obtained after molding.
[0050] Catalyst C (prepared in Comparative Example 1) was used in a tank reactor for the carboxylation reaction of propylene oxide and carbon dioxide. The test method was the same as that of Example 3, and the product contained 7.8% by weight of propylene oxide and 568 g of propylene carbonate.
[0051] Comparative Example 2:
[0052] Preparation of Catalyst D:
[0053] Magnesium nitrate hexahydrate and calcium nitrate were prepared in a molar ratio of 5:1 in the same manner as in Example 1, and catalyst D was obtained after molding.
[0054] Catalyst D (prepared in Comparative Example 2) was used in a tank reactor for the carboxylation reaction of propylene oxide and carbon dioxide. The test method was the same as that of Example 3, and the product contained 4.8% by weight of propylene oxide and 522 g of propylene carbonate.
[0055] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.
[0056] This background section is provided to generally present the context of the invention, and the work of the presently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither explicitly nor implicitly admitted to be prior art to the present invention.
Claims
1. A halogen-free alkaline earth metal-based catalyst, characterized in that: The catalyst comprises a first component, a second component and a third component; calcium and magnesium alkaline earth metal oxides are used as the first component, the first component accounts for 60%-90% of the total mass of the catalyst, and the molar ratio of magnesium to calcium is 3-6:1; aluminum salt is used as the second component, the second component accounts for 10%-40% of the total mass; silver salt is used as the third component, the third component accounts for 0.01%-0.5% of the total mass, and the sum of the total mass percentages is 100%.
2. The use of a halogen-free alkaline earth metal-based catalyst in a carboxylation reaction as claimed in claim 1, characterized in that: The catalytic system of the carboxylation reaction comprises a catalyst and a solvent; wherein the solvent is dimethylformamide, and the added amount of the solvent is 1-10 times the mass of the catalyst.
3. The method for preparing the halogen-free alkaline earth metal-based catalyst according to claim 1, characterized in that The following steps are involved: (1) Weighing the active component in proportion, and then preparing the active component into an aqueous solution with a mass fraction of 15% to 17%; and preparing a precipitant aqueous solution at the same time, wherein the concentration of the precipitant aqueous solution is equal to the concentration of the active component aqueous solution; (2) adding the active component aqueous solution and the precipitant aqueous solution into the precipitation kettle at a certain rate, stirring while adding; after the addition is completed, when the solution temperature reaches 98±2°C, the oil bath temperature is lowered to 102±2°C, stirring is maintained for 1-1.5 hours, and then allowed to stand for more than 5 hours; (3) cooling and filtering the substance finally obtained in (2) to obtain a white solid; (4) The white solid obtained in (3) was washed three times with deionized water and then dried at 120±2°C to constant weight; (5) The material finally obtained in (4) is immersed in an equal volume of an aqueous solution containing silver nitrate for 5-10 hours, then dried to constant weight and calcined to obtain a halogen-free alkaline earth metal-based catalyst.
4. The method for preparing the halogen-free alkaline earth metal-based catalyst according to claim 3, characterized in that: The active component is selected from nitrate or chloride thereof; the precipitant is urea.
5. The method for preparing the halogen-free alkaline earth metal-based catalyst according to claim 3, characterized in that: In step (1), in order to fully dissolve the active component and the precipitant, they are heated to 90±2° C. during dissolution.
6. The method for preparing the halogen-free alkaline earth metal-based catalyst according to claim 3, characterized in that: The rate in step (2) is 8-10 mL / s.
7. The method for preparing the halogen-free alkaline earth metal-based catalyst according to claim 3, characterized in that: The drying temperature in step (5) is 120±2°C; the calcination temperature is 800±50°C, and the time is 1 hour.
8. The method for preparing the halogen-free alkaline earth metal-based catalyst according to claim 3, characterized in that: The catalyst obtained after calcination in step (5) is pressed into tablets to obtain a halogen-free alkaline earth metal-based catalyst.
9. A halogen-free alkaline earth metal-based catalyst prepared by the method according to any one of claims 3 to 8, characterized in that: When the catalyst is used for the carboxylation reaction of propylene oxide, in a fully mixed flow reactor, the carbon dioxide pressure is 1-5MPa, the temperature is 130-150°C, the reaction time is 3-5 hours, the propylene oxide conversion rate is greater than 99%, the yield of propylene carbonate is greater than 70%; based on propylene carbonate, the space-time yield is greater than 11g / h·gcat.
10. A halogen-free alkaline earth metal-based catalyst prepared by the method according to any one of claims 3 to 8, characterized in that: When the catalyst undergoes propylene oxide carboxylation reaction in a plug flow reactor, the carbon dioxide pressure is 1-5MPa, the temperature is 130-150°C, the residence time is 50-70 minutes, the propylene oxide conversion rate is greater than 99%, the propylene carbonate yield is greater than 65%; and the space-time yield is greater than 40g / h·gcat based on propylene carbonate.