A sulfonic solid acid catalyst, a preparation method thereof, and a method for catalyzing isomerization of a ketone azine into 2-pyrazoline

Abstract

The application provides a sulfonic acid solid acid catalyst and a preparation method thereof and a method for catalyzing keto-nitrogen isomerization into 2-pyrazoline, and belongs to the technical field of novel aerospace fuels, so as to solve the technical problems of catalyst separation and recovery difficulty and large acid-containing wastewater discharge in the keto-nitrogen isomerization cyclization method catalyzed by a homogeneous acid. The solid acid catalyst mainly comprises methyl sulfonic acid and a carrier amorphous silica, and the main feature of the solid acid catalyst is a high B acid center. In addition, the application provides a method for synthesizing 2-pyrazoline by catalyzing keto-nitrogen isomerization with a sulfonic acid solid acid catalyst, compared with a traditional homogeneous acid method, the catalyst can be easily separated from the reaction system and can be recycled, so that the production cost is reduced; the generation of a large amount of acid-containing wastewater in the removal process of the acid catalyst is solved, so that the wastewater treatment cost is greatly reduced; the method has high catalytic efficiency, and the catalyst can be recycled for three times, so that the catalytic efficiency is maintained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new aerospace fuels, and particularly relates to a sulfonic acid solid acid catalyst, a preparation method thereof, and a method for catalyzing isomerization of ketone hydrazine into 2-pyrazoline. BACKGROUND

[0002] Developing new high-performance propellants is a key to major breakthroughs in the aerospace field. Liquid propellants widely use high-energy fuels such as hydrazine, unsymmetrical dimethylhydrazine, kerosene, and liquid hydrogen to complete aerospace launch tasks such as the Long March series and the Falcon series. However, the currently used propellants have disadvantages such as great toxicity, easy volatilization, and low energy.

[0003] According to public data, cyclopropyl liquid hydrocarbon fuels have advantages such as high volumetric heat value, low freezing point, small dynamic viscosity (better flow performance), and good material compatibility. Increasing the research and development of liquid hydrocarbon fuels with a cyclopropyl ring structure will help China's technical research and development of a descending stage variable thrust liquid oxygen kerosene engine for manned moon landing and the performance improvement of a new generation of launch vehicles. Currently, cyclopropyl liquid hydrocarbon fuels are mainly obtained by high-temperature denitrification of 2-pyrazoline.

[0004]

[0005] Currently, the traditional synthesis method of 2-pyrazoline is mainly a homogeneous acid catalysis isomerization cyclization method of ketone hydrazine, as shown in formula III, that is, ketone hydrazine is subjected to isomerization cyclization under the catalysis of liquid acids such as hydrochloric acid and acetic acid to obtain 2-pyrazoline. Although this method is widely used, it mainly has the following disadvantages: 1. Because the acid catalyst and the reactant are homogeneous, separation and recovery are difficult; 2. The separation and removal process of the acid catalyst will generate a large amount of acid-containing wastewater, which will greatly increase the wastewater treatment cost; 3. The acid catalyst is difficult to recycle and use, which increases the production cost. SUMMARY

[0006] In view of the technical problems of catalyst separation and recovery difficulty and large amount of acid-containing wastewater discharge in the homogeneous acid catalysis isomerization cyclization method of ketone hydrazine, the application provides a sulfonic acid solid acid catalyst, a preparation method thereof, and a method for catalyzing isomerization of ketone hydrazine into 2-pyrazoline. The prepared sulfonic acid solid acid can effectively overcome the problems of catalyst separation and recovery difficulty and large amount of acid-containing wastewater discharge in the traditional homogeneous acid method, and provides a potential technical path for environment-friendly industry.

[0007] In order to achieve the above-mentioned purposes, the technical scheme of the application is as follows:

[0008] A preparation method of a sulfonic acid solid acid catalyst, the steps being as follows:

[0009] (1) Mix an organosilicon and a sulfonic acid to form a uniform solution;

[0010] (2) adding an acidic reagent, stirring until gelling, forming a catalyst intermediate;

[0011] (3) aging and drying the catalyst intermediate, forming a sulfonic solid acid catalyst having B acid active sites.

[0012] The molar ratio of the organosilicon source, the sulfonic acid and the acidic reagent is 1:(0.5-2):(20-40).

[0013] The organosilicon source is ethyl orthosilicate; the sulfonic acid is one or two or more of trifluoromethanesulfonic acid, methylsulfonic acid, chlorosulfonic acid, hexylsulfonic acid, 1,2-ethanedisulfonic acid and vinylsulfonic acid; and the acidic reagent is any one of formic acid, acetic acid or propionic acid.

[0014] The aging of the catalyst intermediate in step (3) is normal temperature aging, for 12-24 h; and the drying is vacuum drying, at a temperature of 100-120℃ for 6-12 h.

[0015] The steps (1) to (3) are all carried out under an inert gas atmosphere.

[0016] A sulfonic solid acid catalyst, comprising an amorphous silica carrier and methylsulfonic acid, with B acid as the active site.

[0017] A method for catalyzing the isomerization of a ketone azine into 2-pyrazoline by a sulfonic solid acid catalyst, comprising the following steps: mixing the ketone azine and the sulfonic solid acid catalyst, and reacting to prepare the 2-pyrazoline compound.

[0018] The ketone azine has the structural formula as shown in formula I:

[0019]

[0020] The 2-pyrazoline compound has the structural formula as shown in formula II:

[0021]

[0022] The reaction is carried out under a nitrogen atmosphere.

[0023] The reaction is carried out at a temperature of 40-100℃ for 6-8 h.

[0024] The molar ratio of the ketone azine to the sulfonic solid acid catalyst is (100:1)-(25:1).

[0025] The present application has the following advantages: using ketone azine as the raw material and a sulfonic solid acid catalyst with high B acid sites as the catalyst, the isomerization of the ketone azine into 2-pyrazoline is carried out under mild conditions, and the 2-pyrazoline compound is obtained in high yield and high purity. Figure 7As shown, isomerization cyclization synthesis 2-pyrazoline compounds, using B acid and L acid double active site synergies, efficient isomerization synthesis 2-pyrazoline compounds, its principle as shown in Figure 8 and 9 The following significant advantages compared to traditional homogeneous acid method: 1, the catalyst is easy to separate from the reaction system, and can be recycled, reducing production costs; 2, solve the acid catalyst removal process of a large number of acid wastewater, greatly reducing the cost of wastewater treatment; 3, with high catalytic efficiency, while recycling three times, keep good catalytic efficiency. The method involved in the present invention is successfully implemented, which provides a potential technical path for environment-friendly industry. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creating any creative labor.

[0027] Figure 1 IR spectrum of the product 3,5,5-trimethyl-2-pyrazoline of example 1.

[0028] Figure 2 The product 3,5,5-trimethyl-2-pyrazoline of example 1 1 H NMR and 13 C NMR spectrum.

[0029] Figure 3 IR spectrum of the product 3,5-dimethyl-5-methyl-2-pyrazoline of example 2.

[0030] Figure 4 The product 3,5-dimethyl-5-methyl-2-pyrazoline of example 2 1 H NMR and 13 C NMR spectrum.

[0031] Figure 5 IR spectrum of the product 3,5-dimethyl-5-methyl-2-pyrazoline of example 3.

[0032] Figure 6 The product 3,5-dimethyl-5-methyl-2-pyrazoline of example 3 1 H NMR and 13 C NMR spectrum.

[0033] Figure 7 Schematic diagram of the interaction between methane sulfonic acid and silica carrier.

[0034] Figure 8 The acid center mechanism of catalyst L.

[0035] Figure 9 The acid center mechanism of catalyst B. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort fall within the protection scope of the present application.

[0037] Embodiment 1

[0038] A sulfonic acid solid acid catalyst, the preparation method comprising the following steps:

[0039] 0.1 mol of tetraethyl orthosilicate is weighed in a conical flask, and nitrogen is used for replacement, so that the system is always in an inert environment. Then, 0.1 mol of methyl sulfonic acid is added dropwise to the system, and stirring is continued for ten minutes. Then, 3 mol of anhydrous formic acid is added dropwise to the system, and stirring is continued until it forms a gel at a certain moment, and then the stirring is stopped, and the system is kept inert. The system is aged at room temperature for 12 hours. After aging, the system is placed in a vacuum drying oven, and dried at 100 DEG C for 6 hours. Then, the system is taken out, and ground with a pestle to obtain a sample of the prepared methyl sulfonic acid solid acid catalyst.

[0040] The following application examples 1-5 all use the methyl sulfonic acid solid acid catalyst prepared in embodiment 1.

[0041] Application example 1

[0042] A sulfonic acid solid acid catalyst catalyzes isomerization and cyclization of acetone ketazine to obtain 3,5,5-trimethyl-2-pyrazoline, and the steps are as follows:

[0043] 1) Acetone ketazine (0.5 mol, 56 g) is added to a 500 mL three-necked flask, and nitrogen is continuously introduced to make the system in an inert environment.

[0044] 2) Then, 5.9 g (active component: 0.85 mmol / g) of the methyl sulfonic acid solid acid catalyst is added.

[0045] 3) The stirring is started at 300 rpm, and heating is started, and the temperature is slowly increased to 85 DEG C, and the reaction is carried out for 8 hours.

[0046] 4) The temperature is decreased to room temperature, and the internal standard method is used for quantitative analysis by using Agilent GC-8890. Figure 1 and Figure 2The infrared and nuclear magnetic resonance spectra confirmed the successful preparation of 3,5,5-trimethyl-2-pyrazoline.

[0047] Application Example 2

[0048] A sulfonic acid solid acid catalyst catalyzes the azo-isomerization cyclization of butanone to yield 3,5-diethyl-5-methyl-2-pyrazoline, the steps of which are as follows:

[0049] 1) Add 0.5 mol, 70 g of butanone ketazine to a 500 mL three-necked flask and continuously purge with nitrogen gas to keep the system in an inert environment.

[0050] 2) Next, add 11.3g (active component: 0.85mmol / g) of methanesulfonic acid solid acid catalyst;

[0051] 3) Start stirring at 300 rpm, turn on heating, and slowly raise the temperature to 95°C. React for 8 hours.

[0052] 4) After cooling to room temperature, the internal standard method was used, and quantitative analysis was performed using an Agilent GC-8890 analyzer. (Combined with...) Figure 3 and Figure 4 The infrared and nuclear magnetic resonance spectra confirmed the successful preparation of 3,5-diethyl-5-methyl-2-pyrazoline.

[0053] Application Example 3

[0054] A sulfonic acid-based solid acid catalyst catalyzes the azo-isomerization cyclization of pentanone to yield 3,5-dipropyl-5-methyl-2-pyrazoline, the steps of which are as follows:

[0055] 1) Add 1 mol, 168 g of pentoketone ketazine to a 500 mL three-necked flask and continuously purge with nitrogen gas to keep the system in an inert environment.

[0056] 2) Next, add 23.5g (active component: 0.85mmol / g) of methanesulfonic acid solid acid catalyst;

[0057] 3) Start stirring at 300 rpm, turn on heating, and slowly raise the temperature to 90°C. React for 8 hours.

[0058] 4) After cooling to room temperature, the internal standard method was used, and quantitative analysis was performed using an Agilent GC-8890 analyzer. (Combined with...) Figure 5 and Figure 6 The infrared and nuclear magnetic resonance spectra confirmed the successful preparation of 3,5-dipropyl-5-methyl-2-pyrazoline.

[0059] Application Example 4

[0060] A sulfonic acid solid acid catalyst catalyzes the azo isomerization cyclization of 4-methyl-2-pentanone to yield 3,5-diisobutyl-5-methyl-4,5-dihydro-1H-pyrazole, the steps of which are as follows:

[0061] 1) 4-methyl-2-pentanone ketone azine (0.5 mol, 98 g) was added to a 500 mL three-necked flask, continuously purging nitrogen to make the system inert;

[0062] 2) Then 23.5 g (active component: 0.85 mmol / g) of a solid acid catalyst of methyl sulfonic acid was added;

[0063] 3) Stirring was started at 300 rpm, heating was started, and the temperature was slowly raised to 95°C, and the reaction was carried out for 8 h;

[0064] 4) The temperature was lowered to room temperature, and quantitative analysis was carried out by internal standard method using Agilent GC-8890.

[0065] Application Example 5

[0066] A sulfonic acid solid acid catalyst catalyzes the isomerization and cyclization of cyclopropyl ketone azine to obtain 5-methyl-3,5-dicyclopropylpyrazoline, and the steps are as follows:

[0067] 1) Cyclopropyl ketone azine (0.5 mol, 84 g) was added to a 500 mL three-necked flask, continuously purging nitrogen to make the system inert;

[0068] 2) Then 11.3 g (active component: 0.85 mmol / g) of a solid acid catalyst of methyl sulfonic acid was added;

[0069] 3) Stirring was started at 300 rpm, heating was started, and the temperature was slowly raised to 95°C, and the reaction was carried out for 8 h;

[0070] 4) The temperature was lowered to room temperature, and quantitative analysis was carried out by internal standard method using Agilent GC-8890.

[0071] Comparative Application Example

[0072] A sulfonic acid catalyst catalyzes the isomerization and cyclization of cyclopropyl ketone azine to obtain 5-methyl-3,5-dicyclopropylpyrazoline, and the steps are as follows:

[0073] 1) Cyclopropyl ketone azine (0.5 mol, 84 g) was added to a 500 mL three-necked flask, continuously purging nitrogen to make the system inert;

[0074] 2) Then 9.6 mmol of a catalyst of methyl sulfonic acid was added;

[0075] 3) Stirring was started at 300 rpm, heating was started, and the temperature was slowly raised to 95°C, and the reaction was carried out for 8 h;

[0076] 4) The temperature was lowered to room temperature, and quantitative analysis was carried out by internal standard method using Agilent GC-8890.

[0077] Recovery of the solid acid catalyst

[0078] The steps for recovering solid methanesulfonic acid catalyst are as follows:

[0079] After the reaction in Application Examples 1-5 is completed, and the reaction solution has cooled to room temperature, the solid acid catalyst is filtered and recovered using a 0.25 μm nylon organic filter membrane, washed, and vacuum dried for recycling. The cyclic reaction is carried out under the same conditions as in Application Examples 1-5 (including reaction temperature, molar ratio, stirring speed, and reaction time).

[0080] Table 1. Experimental data from Application Examples 1-5

[0081] Item Conversion rate Selectivity Application Example 1 96.2 99.2 Application Example 2 95.0 99.5 Application Example 3 93.1 98.5 Application Example 4 45.3 99.0 Application Example 5 69.6 74.7 Comparative Application Example 49.8 73.2

[0082] Table 2 shows the experimental conditions for repeated use of Examples 1-5 (methanesulfonic acid solid acid catalyst is recycled).

[0083]

[0084]

[0085] Application Examples 1-5 and the cycle stability test of the methanesulfonic acid solid acid catalyst are shown in Tables 1 and 2. Table 1 shows that the supported catalyst has good versatility and, corresponding to Application Examples 1-2, has excellent catalytic efficiency and a significant improvement in conversion rate compared to sulfonic acid alone.

[0086] Table 2 illustrates that the supported catalyst has good cyclic practicality: 1. The catalyst is easy to separate from the reaction system and can be recycled, reducing production costs; 2. It solves the problem of generating a large amount of acid-containing wastewater during the removal of acid catalysts, greatly reducing wastewater treatment costs; 3. It has both high catalytic efficiency and can be recycled three times to maintain good catalytic efficiency.

[0087] Example 2

[0088] A sulfonic acid-based solid acid catalyst, the preparation method includes the following steps:

[0089] Weigh 0.1 mol of tetraethyl orthosilicate into an Erlenmeyer flask and purge with nitrogen to maintain an inert environment. Then, add 0.1 mol of chlorosulfonic acid dropwise while stirring for ten minutes. Next, add 2 mol of anhydrous formic acid dropwise while stirring until a gel forms instantaneously at a certain point. Stop stirring and maintain the system inert for 24 hours at room temperature. After aging, place the sample in a vacuum drying oven and dry at 100°C for 6 hours. Remove the sample and grind it with a pestle to obtain the prepared methanesulfonic acid solid acid catalyst.

[0090] Example 3

[0091] A sulfonic acid solid acid catalyst, the preparation method comprising the following steps:

[0092] Take 0.1 mol of tetraethyl orthosilicate in a conical flask, and replace it with nitrogen to keep the system in an inert environment. Then, add 0.2 mol of trifluoromethanesulfonic acid dropwise to the system, continuously stir for ten minutes, and then add 2 mol of anhydrous acetic acid dropwise to it. Continue stirring until it forms a gel at a certain moment, stop stirring, and keep the system inert. Age it at room temperature for 15 hours. After aging, place it in a vacuum drying oven, dry it at 120°C for 8 hours, take it out, and grind it with a pestle. The sample of the methyl sulfonic acid solid acid catalyst is prepared.

[0093] Example 4

[0094] A sulfonic acid solid acid catalyst, the preparation method comprising the following steps:

[0095] Take 0.1 mol of tetraethyl orthosilicate in a conical flask, and replace it with nitrogen to keep the system in an inert environment. Then, add 0.05 mol of 1,2-ethanedisulfonic acid dropwise to the system, continuously stir for ten minutes, and then add 4 mol of anhydrous formic acid dropwise to it. Continue stirring until it forms a gel at a certain moment, stop stirring, and keep the system inert. Age it at room temperature for 16 hours. After aging, place it in a vacuum drying oven, dry it at 110°C for 6 hours, take it out, and grind it with a pestle. The sample of the methyl sulfonic acid solid acid catalyst is prepared.

[0096] Example 5

[0097] A sulfonic acid solid acid catalyst, the preparation method comprising the following steps:

[0098] Take 0.1 mol of tetraethyl orthosilicate in a conical flask, and replace it with nitrogen to keep the system in an inert environment. Then, add 0.1 mol of methyl sulfonic acid dropwise to the system, continuously stir for ten minutes, and then add 3 mol of anhydrous propionic acid dropwise to it. Continue stirring until it forms a gel at a certain moment, stop stirring, and keep the system inert. Age it at room temperature for 12 hours. After aging, place it in a vacuum drying oven, dry it at 100°C for 10 hours, take it out, and grind it with a pestle. The sample of the methyl sulfonic acid solid acid catalyst is prepared.

[0099] Example 6

[0100] A sulfonic acid solid acid catalyst, the preparation method comprising the following steps:

[0101] Take 0.1 mol of ethyl orthosilicate in a conical flask, and replace it with nitrogen to keep the system in inert environment, then add 0.1 mol of vinyl sulfonic acid drop by drop to the system, continue stirring for ten minutes, then add 3 mol of anhydrous formic acid drop by drop to it, continue stirring until it forms a gel at a certain time, then stop stirring, keep the system inert, and age at room temperature for 12 hours. After aging, put it in a vacuum drying oven, dry at 100°C for 6 hours, take it out, and grind it with a pestle. The sample, methyl sulfonic acid solid acid catalyst, is obtained.

[0102] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A process for the isomerization of ketone azine into 2-pyrazoline catalyzed by a sulfonic solid acid catalyst, characterized in that, The steps are as follows: mixing and reacting the ketone hydrazones and the sulfonic acid solid acid catalyst to prepare 2-pyrazoline compounds; The ketone hydrazones have the structural formula as shown in the formula: ； The structural formula of the 2-pyrazoline compound is as shown in the following formula (I): (I) ； The preparation method of the sulfonic acid solid acid catalyst comprises the following steps: (1) mixing an organic silicon source and a sulfonic acid to form a uniform solution; (2) adding an acidic reagent and stirring until a gel is formed to form a catalyst intermediate; (3) aging and drying the catalyst intermediate to form the sulfonic acid solid acid catalyst with B acid active centers; The molar ratio of the organic silicon source, the sulfonic acid and the acidic reagent is 1:(0.5-2):(20-40); The organic silicon source is tetraethyl orthosilicate; the sulfonic acid is one or two or more of trifluoromethane sulfonic acid, methyl sulfonic acid, chlorosulfonic acid, hexyl sulfonic acid, 1,2-ethanedithioic acid and vinyl sulfonic acid; and the acidic reagent is any one of formic acid, acetic acid or propionic acid; The aging of the catalyst intermediate in the step (3) is normal temperature aging, and the time is 12-24 h; the drying is vacuum drying, the vacuum drying temperature is 100-120 DEG C, and the time is 6-12 h; The steps (1) to (3) are all carried out in an inert gas atmosphere.

2. The process for isomerization of ketone azine into 2-pyrazoline catalyzed by sulfonic solid acid catalyst according to claim 1, characterized in that, The reaction atmosphere is a nitrogen atmosphere.

3. The process for isomerization of ketone azine into 2-pyrazoline catalyzed by sulfonic solid acid catalyst according to claim 1, characterized in that, The reaction temperature is 40-100 DEG C, and the time is 6-8 h.

4. The process for isomerization of ketone azine into 2-pyrazoline catalyzed by sulfonic solid acid catalyst according to claim 1, characterized in that, The molar ratio of the ketone hydrazones to the sulfonic acid solid acid catalyst is (100:1)-(25:1).

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