The invention relates to a high-energy synthetic fuel 1apos; -methyl-1, 1apos,-methyl-1, 1apos; 2apos, 2apos; , 1apos; carrying out apos; method for purifying-tricyclopropane

Abstract

The invention discloses a purification method of high-energy synthetic fuel 1 '-methyl-1, 1': 2 ', 1' '-tricyclopropane, which comprises the following steps: (1) mixing a 1'-methyl-1, 1 ': 2', 1 ''-tricyclopropane crude product with acid, stirring, and standing the mixture for liquid separation; (2) mixing the supernatant liquid with alkali, stirring, and standing and separating the mixture; and (3) taking the supernatant liquid, and drying to obtain the purified product 1 '-methyl-1, 1': 2 ', 1' '-tricyclopropane. According to the method disclosed by the invention, impurities such as cyclopropyl ketone, water, azine, pyrazoline, nitrogen-containing high polymers and the like in the 1 '-methyl-1, 1': 2 ', 1' '-tricyclopropane crude product can be efficiently removed, and the purified product meets the requirements of aerospace fuel quality. Besides, only two-step reaction and one-step drying treatment are needed in the purification process, operation is easy, cost is low, efficiency is high, meanwhile, the drying agent can be regenerated, and a feasible scheme is provided for medium and small-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of fuels, and in particular relates to a method for purifying high-energy synthetic fuel 1'-methyl-1,1':2',1"-tricyclopropane. Background Art

[0002] Aerospace fuel is the energy source of the power system. Almost all current fuels are obtained by refining petroleum and coal. Although the sources are relatively wide, the performance cannot be further improved due to the fixed fuel composition and low energy of the molecular structure. 1,2-Dicyclopropyl-1-methylcyclopropane, also known as 1′-methyl-1,1′:2′,1″-tricyclopropane, is a synthetic liquid fuel. Due to its ternary tensile ring structure, the specific impulse of this substance is greatly improved compared with the current rocket fuel, which helps to increase the payload of the carrier.

[0003] The synthesis of 1′-methyl-1,1′:2′,1″-tricyclopropane uses cyclopropyl ketone and hydrazine hydrate as the main raw materials, undergoes three steps of reaction to obtain the crude product 1′-methyl-1,1′:2′,1″-tricyclopropane, and then distills it to obtain the pure product. However, due to chemical equilibrium and side reactions, the crude product contains unreacted cyclopropyl ketone, water, intermediate products azine, pyrazoline and nitrogen-containing polymers. Among them, excessive water content will cause the fuel to precipitate crystals at low temperatures, clogging the filter or pipeline; the presence of cyclopropyl ketone will reduce the flash point of 1′-methyl-1,1′:2′,1″-tricyclopropane, posing a safety hazard. In addition, azine, pyrazoline and polymers are easily oxidized, which reduces the quality of the oil and generates actual colloids, seriously affecting the thermal stability and anti-coking properties of 1′-methyl-1,1′:2′,1″-tricyclopropane. Therefore, 1′-methyl-1,1′:2′,1″-tricyclopropane must be fully purified and the impurity content must be strictly controlled before it can be put into engineering applications.

[0004] The Chinese invention patent with publication number CN117623847A discloses a method for purifying 1,2-dicyclopropyl-1-methylcyclopropane, which uses segmented distillation to separate light components and 1′-methyl-1,1′:2′,1″-tricyclopropane in sequence, and the remaining heavy components remain at the bottom of the tower. Finally, phosphomolybdic acid, calcium chloride and other fillers are used for refining to remove the actual colloid remaining in 1′-methyl-1,1′:2′,1″-tricyclopropane to obtain qualified products. However, this process still has great limitations. First, the distillation requires two or more stages of distillation towers, which are complex in structure, cumbersome in operation and expensive in cost, and are not suitable for small and medium-sized scale promotion and application; second, the filler is difficult to regenerate, and becomes a waste solid after refining, which increases the difficulty of post-processing.

[0005] Therefore, it is necessary to provide a purification method which can effectively remove impurities in 1′-methyl-1,1′:2′,1″-tricyclopropane and has a simple and easy operation process and low cost.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for purifying high-energy synthetic fuel 1′-methyl-1,1′:2′,1″-tricyclopropane. The method of the present invention can efficiently remove impurities such as cyclopropyl ketone, water, azine, pyrazoline, nitrogen-containing polymers, etc. in crude 1′-methyl-1,1′:2′,1″-tricyclopropane, and the purified product meets the quality requirements of aerospace fuel. In addition, the purification process of the present invention only requires two-step reaction and one-step drying treatment, which is simple to operate, low in cost, and high in efficiency. At the same time, the desiccant can be regenerated, providing a feasible solution for small and medium-scale production.

[0008] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0009] The present invention provides a method for purifying high-energy synthetic fuel 1′-methyl-1,1′:2′,1″-tricyclopropane, comprising:

[0010] (1) mixing the crude 1′-methyl-1,1′:2′,1″-tricyclopropane product with an acid, stirring, and allowing the mixture to stand for separation;

[0011] (2) taking the upper layer of liquid and mixing it with alkali, stirring it, and letting the mixture stand to separate the liquids;

[0012] (3) The upper layer of liquid is taken and dried to obtain a purified product, 1′-methyl-1,1′:2′,1″-tricyclopropane.

[0013] The main impurities in the crude 1′-methyl-1,1′:2′,1″-tricyclopropane include cyclopropyl ketone, water, azine, pyrazoline and nitrogen-containing polymers. The purification method of the present invention firstly performs the steps of acid treatment and liquid separation to remove azine, pyrazoline and nitrogen-containing polymers; then performs the steps of alkali treatment and liquid separation to remove cyclopropyl ketone, and finally performs drying treatment to remove residual water. Therefore, the method of the present invention only requires two-step reaction and one-step drying treatment, is simple to operate, is easy to remove impurities, has low cost and high efficiency, and the desiccant can be regenerated, thereby providing a feasible solution for small and medium-scale production.

[0014] In a further embodiment, in step (1), the acid is selected from a combination of one or more of hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, methanesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, trifluoroacetic acid, and trichloroacetic acid.

[0015] Preferably, the acid comprises water, and the content of the water is 5%-66%.

[0016] Among the acids, the oxygen-free acid exists in the form of an aqueous solution and can be used directly without the need for additional water; whereas the oxygen-containing acid often exists in the form of a pure substance or a high-concentration solution and needs to be diluted with water before use, thereby providing the necessary water for the hydrolysis of azine.

[0017] In the above scheme, the acid promotes the rapid hydrolysis of the residual azine into cyclopropyl ketone and hydrazine, and forms salts with hydrazine and pyrazoline, and at the same time forms salts with nitrogen-containing polymers. The salt substances enter the water phase, and the organic matter is almost insoluble in water. The organic phase and the aqueous phase are separated by standing and separating the liquids, wherein the organic phase is located in the upper layer and the aqueous phase is located in the lower layer. The lower layer liquid is discarded, and the organic phase is retained to obtain the first step treatment product, wherein the impurities are cyclopropyl ketone and water.

[0018] As a preferred embodiment, the acid is hydrochloric acid. Hydrochloric acid is used in the present invention because it is cheap and readily available and does not easily carbonize the reactants. The concentration of commercially available hydrochloric acid is 12 mol / L and the water content is 66%.

[0019] In a further embodiment, the amount of the acid used is determined according to the content of azine and nitrogen-containing polymer in the crude 1′-methyl-1,1′:2′,1″-tricyclopropane.

[0020] In a further embodiment, the mass of the added acid is 25% to 100% of the total mass of azine and nitrogen-containing polymer in the crude 1′-methyl-1,1′:2′,1″-tricyclopropane product;

[0021] Preferably, the mass of the acid is 50% of the total mass of the azine and the nitrogen-containing polymer in the crude 1′-methyl-1,1′:2′,1″-tricyclopropane product.

[0022] As a specific implementation, generally, the content of azine and nitrogen-containing polymer in the crude product is about 8wt%, and the amount of hydrochloric acid is determined to be 2wt% to 8wt%, preferably 4wt%. Too high an amount wastes materials, while too low an amount cannot fully decompose azine.

[0023] In a further embodiment, in step (1), the reaction temperature is room temperature.

[0024] In a further embodiment, in step (2), the base is selected from a combination of one or more of hydrazine, methylhydrazine, and unsymmetrical dimethylhydrazine;

[0025] Preferably, the base is hydrazine.

[0026] In the above scheme, the base (such as hydrazine) undergoes a condensation reaction with the residual cyclopropyl ketone in the organic phase to generate a hydrazone and eliminate one molecule of water. Due to the presence of the residual amino group of the hydrazone, the hydrazone is water-soluble and enters the aqueous phase together with the excess hydrazine. The separation is completed by standing the liquid and discarding the lower aqueous phase. The organic phase is retained to obtain the second step treatment product, in which the impurity is water.

[0027] In a further embodiment, the amount of the base used is determined according to the cyclopropyl ketone content of the crude 1′-methyl-1,1′:2′,1″-tricyclopropane after treatment in step (1).

[0028] In a further embodiment, the mass of the added base is 20% to 45% of the mass of the cyclopropyl ketone after the crude 1′-methyl-1,1′:2′,1″-tricyclopropane product is treated in step (1);

[0029] Preferably, the mass of the base is 27% of the mass of cyclopropyl ketone after the crude 1′-methyl-1,1′:2′,1″-tricyclopropane product is treated in step (1).

[0030] As a specific implementation method, generally, when the content of azine and nitrogen-containing polymer in the crude product is about 8%, after the first step of treatment, the content of cyclopropyl ketone in the crude product is about 9%, and the amount of hydrazine is determined to be 2% to 4%, preferably 2.5%. If the amount is too high, the material will be wasted, and if the amount is too low, it will not fully react with cyclopropyl ketone, resulting in residual cyclopropyl ketone.

[0031] In a further embodiment, in step (2), the reaction temperature is room temperature.

[0032] Furthermore, in step (2), the reaction time is 1 h to 3 h, preferably 1 h.

[0033] In a further embodiment, a desiccant is used for drying in step (3);

[0034] Preferably, the desiccant is selected from a combination of one or more of anhydrous sodium sulfate, polyacrylamide, mesoporous γ-alumina, and 5A molecular sieve;

[0035] Preferably, the desiccant is mesoporous γ-alumina.

[0036] In the above scheme, the γ-alumina is a commercially available product, which has a 40-mesh spherical appearance and a hydrophilic surface, and its BET specific surface area is as high as 280 m 2 / g, can quickly absorb residual water, strong adsorption capacity, the final water content does not exceed 50ppm. And γ-alumina is easy to regenerate, after filtering, vacuum microwave treatment can restore the drying capacity.

[0037] In a further embodiment, the mass of the desiccant is 0.1% to 2% of the mass of the crude product of 1′-methyl-1,1′:2′,1″-tricyclopropane;

[0038] Preferably, the mass of the desiccant is 1% of the mass of the crude 1′-methyl-1,1′:2′,1″-tricyclopropane product.

[0039] Furthermore, the drying process in step (3) is as follows: a desiccant (e.g., γ-alumina) is added to the top of a stainless steel column at a volume space velocity of 4 min -1 The crude product to be dehydrated is injected, and the final purified product is received from the bottom.

[0040] In a further embodiment, the temperature of the purification process is room temperature.

[0041] In the purification method of the present invention, the reaction temperature is room temperature. This is because the flash point of 1′-methyl-1,1′:2′,1″-tricyclopropane is only 42° C. In order to avoid fire hazards, heating conditions are not used. Since the reaction is slow at low temperatures, lower temperatures are not used.

[0042] In a further embodiment, the crude 1′-methyl-1,1′:2′,1″-tricyclopropane product contains no less than 70%wt of 1′-methyl-1,1′:2′,1″-tricyclopropane;

[0043] Preferably, the main impurities in the crude 1′-methyl-1,1′:2′,1″-tricyclopropane include cyclopropyl ketone, water, azine, pyrazoline, and nitrogen-containing polymers.

[0044] In a further embodiment, in the purification method of the present invention, a glass, enamel-lined or stainless steel reactor is used in the reaction process; and a liquid separation kettle is used in the static liquid separation process.

[0045] The present invention also provides a pure product of 1′-methyl-1,1′:2′,1″-tricyclopropane prepared by the above purification method;

[0046] Preferably, in the pure 1′-methyl-1,1′:2′,1″-tricyclopropane, the content of cyclopropyl ketone is less than 150 ppm, and the content of water is less than 100 ppm;

[0047] More preferably, in the pure product of 1′-methyl-1,1′:2′,1″-tricyclopropane, azine, pyrazoline and nitrogen-containing polymers are completely removed.

[0048] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0049] 1. The present invention sequentially removes nitrogen-containing substances, cyclopropyl ketone and water in the crude product of 1′-methyl-1,1′:2′,1″-tricyclopropane by using acid, alkali and desiccant. Therefore, the method of the present invention only requires two-step reaction and one-step drying treatment, has simple operation steps, can quickly and efficiently remove impurities, so that the content of cyclopropyl ketone in the purified 1′-methyl-1,1′:2′,1″-tricyclopropane product is less than 150 ppm, the content of water is less than 100 ppm, and azine, pyrazoline and nitrogen-containing polymers are completely removed.

[0050] 2. The purification method of the present invention has a fast processing process and requires simple equipment. It can be completed with simple devices such as a reaction kettle and a liquid separator, and there is no need to design and build a distillation tower, so the cost is low.

[0051] 3. The impurity removal reagents (acids and alkalis) used in the purification method of the present invention are relatively cheap, and the desiccant is regenerable, so the output of the three wastes is controlled, which is more environmentally friendly.

[0052] In summary, the purification method of the present invention can remove impurities efficiently, and the operation process is simple and the cost is low, which lays a foundation for the promotion of purification methods of 1′-methyl-1,1′:2′,1″-tricyclopropane and its analogs on a small and medium scale. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in combination with the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0054] Detection method:

[0055] Water: Determined by Karl-Fischer method. Use a syringe to extract 0.1 mL of the sample to be tested, inject it into the reaction solution of the Karl-Fischer water analyzer, and read the value from the instrument screen after the reading stabilizes, which is the water content of the sample.

[0056] Other organic matter except water: Determined by gas chromatography, equipped with hydrogen flame ionization detector and DB-5 capillary column (30m*0.25mm*0.25μm), carrier gas N2 flow rate 0.8mL / min, injection port temperature 260℃, step heating rate 10℃ / min, detector background temperature 260℃. According to the peak area normalization method, the content of each component is calculated by the peak area ring ratio after deducting the water content.

[0057] Example 1

[0058] (1) 30 kg of crude 1′-methyl-1,1′:2′,1″-tricyclopropane and 1.2 kg of 12 mol / L hydrochloric acid were injected into a 50 L glass reactor, maintained at room temperature, and stirred vigorously at 300 rpm for 10 min;

[0059] (2) The reaction solution was transferred into a 50 L separatory kettle and allowed to stand for 2 h. The lower layer of liquid was slowly discharged after observation by a liquid level gauge.

[0060] (3) The upper layer of liquid was transferred to another 50 L glass reactor, 750 g of hydrazine was injected, and the reaction was vigorously stirred at 300 rpm for 2 h;

[0061] (4) The reaction solution was transferred into a 50 L separatory kettle and allowed to stand for 2 h. The lower layer of liquid was slowly discharged after observation by a liquid level gauge.

[0062] (5) A stainless steel column (inner diameter 80 mm, length 400 mm) filled with 300 g of γ-alumina was charged with a volumetric space velocity of 4 min. -1 The organic phase liquid from the previous step is injected and the final purified product is received from the bottom.

[0063] The contents of various substances in the original crude product and the purified product are shown in Table 1, where the remainder refers to other substances whose structures cannot be accurately known, and it has been verified that they have no effect on the quality and performance of the fuel.

[0064] Table 1

[0065]

[0066]

[0067] Embodiment 2-7

[0068] The difference between Example 2-7 and Example 1 is that the original crude products are taken from different batches of 1′-methyl-1,1′:2′,1″-tricyclopropane crude products (the purity and water content of the crude products are shown in Table 2), and the purification steps and conditions are the same.

[0069] Then, the content of 1′-methyl-1,1′:2′,1″-tricyclopropane and the water content in the purified product obtained in the above Examples 2-7 were analyzed, and the results are shown in Table 2:

[0070] Table 2

[0071]

[0072] It can be seen from the above data that the purification method of the present invention can be used to purify crude fuel products. For crude products with a 1′-methyl-1,1′:2′,1″-tricyclopropane content in the range of 71.7% to 97.1%, a significant purification effect can be achieved, and the purified product can reach a purity of not less than 99.6%.

[0073] Embodiment 8-11

[0074] Examples 8-11 are based on Example 1, except that the types of acid, base and desiccant are changed, and the dosage, purification steps and conditions are the same. The details are shown in the following table.

[0075] Table 3

[0076] Example acid Alkali Desiccant Example 8 Hydrobromic acid Hydrazine γ-Alumina Example 9 sulfuric acid Unsymmetrical dimethylhydrazine Anhydrous sodium sulfate Example 10 Methanesulfonic acid Unsymmetrical dimethylhydrazine 5A molecular sieve Embodiment 11 p-Toluenesulfonic acid Methylhydrazine Polyacrylamide

[0077] Then the content of the substances before and after purification in each embodiment was detected, and the specific results are as follows:

[0078] Table 4

[0079]

[0080] Result analysis: From the above data, it can be seen that the purification method of the present invention can be used to purify the crude fuel product. For the crude 1′-methyl-1,1′:2′,1″-tricyclopropane, a significant purification effect can be achieved, and the purified product can reach a purity of not less than 99.6%. It can be seen that no matter what kind of acid, base, and desiccant used in the present invention, similar effects can be achieved. From the perspective of material cost and catalyst reusability, the treatment combination of hydrochloric acid, hydrazine, and γ-alumina is preferred.

[0081] Comparative Example 1

[0082] The difference between this comparative example and Example 1 is that only the acid treatment process is eliminated, and other conditions are the same.

[0083] Comparative Example 2

[0084] The difference between this comparative example and Example 1 is that only the alkali treatment process is eliminated, and other conditions are the same.

[0085] Comparative Example 3

[0086] The difference between this comparative example and Example 1 is that only the drying process is eliminated, and other conditions are the same.

[0087] Comparative Example 4

[0088] The difference between this comparative example and Example 1 is that the methanesulfonic acid used is not diluted with water, and other conditions are the same.

[0089] The contents of various substances in Example 1 and Comparative Examples 1 to 3 were measured, and the results are shown in Table 5:

[0090] Table 5

[0091]

[0092]

[0093] It should be noted that, in the above table, 1 ppm = 0.0001% = 1 mg / kg.

[0094] It can be seen from the data in Table 5 that compared with Example 1, the residual amount of cyclopropyl ketone in Comparative Example 1 is too high, and it fails to continue to react with hydrazine, and the generated hydrazone enters the water phase and is removed, which will lead to a decrease in the flash point of the product and bring potential safety hazards.

[0095] Compared with Example 2, in Comparative Example 2, azine, pyrazoline and nitrogen-containing polymers were not removed. Such substances are very easy to oxidize and discolor in the air, which seriously affects the thermal stability and anti-coking performance of the product.

[0096] Compared with Example 1, the water content of Comparative Example 3 is too high, and ice crystals are easily precipitated under low temperature conditions, which harms the pipeline and blocks the filter.

[0097] In Comparative Example 4, compared with Example 1, methanesulfonic acid does not contain water and cannot hydrolyze azine. The azine content is high and cannot be significantly removed.

[0098] It can be seen that the present invention can effectively purify the crude product of 1′-methyl-1,1′:2′,1″-tricyclopropane and obtain a high-purity product, the quality of which meets the use requirements in the aerospace field.

[0099] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with the present invention can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A method for purifying high-energy synthetic fuel 1'-methyl-1,1':2',1"-tricyclopropane, characterized in that: include: (1) mixing the crude 1'-methyl-1,1':2',1"-tricyclopropane product with an acid, stirring, and allowing the mixture to stand for liquid separation; (2) taking the upper layer of liquid and mixing it with alkali, stirring it, and letting the mixture stand to separate the liquids; (3) taking the upper liquid layer and drying it to obtain a purified product, 1'-methyl-1,1':2',1"-tricyclopropane.

2. The purification method according to claim 1, characterized in that In step (1), the acid is selected from a combination of one or more of hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, methanesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, trifluoroacetic acid, and trichloroacetic acid; Preferably, the acid includes water, and the content of the water is 5%-66%; Preferably, the acid is hydrochloric acid.

3. The purification method according to claim 1 or 2, characterized in that: The mass of the added acid is 25% to 100% of the total mass of azine and nitrogen-containing polymer in the crude 1'-methyl-1,1':2',1"-tricyclopropane product; Preferably, the mass of the acid is 50% of the total mass of azine and nitrogen-containing polymer in the crude 1'-methyl-1,1':2',1"-tricyclopropane product.

4. The purification method according to claim 1, characterized in that In step (2), the base is selected from a combination of one or more of hydrazine, methylhydrazine, and unsymmetrical dimethylhydrazine; Preferably, the base is hydrazine.

5. The purification method according to claim 1 or 4, characterized in that: The mass of the added base is 20% to 45% of the mass of cyclopropyl ketone after the crude 1'-methyl-1,1':2',1"-tricyclopropane product is treated in step (1); Preferably, the mass of the base is 27% of the mass of cyclopropyl ketone after the crude 1'-methyl-1,1':2',1"-tricyclopropane product is treated in step (1).

6. The purification method according to claim 1, characterized in that: In step (3), a desiccant is used for drying; Preferably, the desiccant is selected from a combination of one or more of anhydrous sodium sulfate, polyacrylamide, mesoporous γ-alumina, and 5A molecular sieve; Preferably, the desiccant is mesoporous γ-alumina.

7. The purification method according to claim 1 or 6, characterized in that: The mass of the desiccant is 0.1% to 2% of the mass of the crude product of 1'-methyl-1,1':2',1"-tricyclopropane; Preferably, the mass of the desiccant is 1% of the mass of the crude 1'-methyl-1,1':2',1"-tricyclopropane product.

8. The purification method according to any one of claims 1 to 7, characterized in that: The temperature of the purification process is room temperature.

9. The purification method according to any one of claims 1 to 8, characterized in that: The crude 1'-methyl-1,1':2',1"-tricyclopropane product has a 1'-methyl-1,1':2',1"-tricyclopropane content of not less than 70%wt; Preferably, the main impurities in the crude 1'-methyl-1,1':2',1"-tricyclopropane include cyclopropyl ketone, water, azine, pyrazoline, and nitrogen-containing polymers.

10. A pure product of 1'-methyl-1,1':2',1"-tricyclopropane prepared by the purification method according to any one of claims 1 to 9; Preferably, in the pure 1'-methyl-1,1':2',1"-tricyclopropane, the content of cyclopropyl ketone is less than 150 ppm, and the content of water is less than 100 ppm; More preferably, in the pure product of 1'-methyl-1,1':2',1"-tricyclopropane, azine, pyrazoline and nitrogen-containing polymers are completely removed.

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