A method for carbon fixation into salicylic acid based on plasma

Abstract

The application relates to the technical field of salicylic acid preparation, in particular to a method for preparing salicylic acid based on plasma carbon fixation, which comprises the following steps: high-purity argon gas with a first preset flow rate is introduced into a reaction cavity; a preset positive voltage is applied to the tip of a corona discharge needle through a high-voltage direct-current power supply, water vapor in the discharge reaction cavity is subjected to corona discharge to form non-adiabatic plasma, wherein a large number of high-activity water cluster radical cations are contained; high-purity argon gas containing benzene steam with a second preset flow rate is introduced into the discharge reaction cavity, the water cluster radical cations are contacted with neutral benzene molecules to react, and hydrogen and phenol radical cations are generated. The application can solve the technical problems of the traditional industrial preparation of salicylic acid, such as high cost of complex device, difficulty in water removal in the production process, poor dispersion state of raw materials, high temperature and high pressure, long reaction time, high energy consumption, use of corrosive reagents, too much waste liquid and waste residue, and difficulty in post-treatment, and the like, which cannot meet the green development requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of salicylic acid preparation, and particularly relates to a method for preparing salicylic acid by fixing carbon based on plasma. BACKGROUND

[0002] CO2 is the product of complete combustion of carbon-containing substances, and can also be used as a raw material for preparing many important organic substances. With the increasing consumption of world energy, the neutralization or conversion of CO2 is becoming more and more important. For example, CO2 is used as a raw material to produce important organic intermediates such as formic acid, dimethylformamide, diphenyl carbonate, dialkyl carbonate, carbamate, cyclic carbonate and salicylic acid derivatives. Among them, salicylic acid, as an important organic substance applied in various aspects such as medical treatment, industry, food, agriculture and the like, is an important research topic in the field of CO2 conversion.

[0003] Salicylic acid, also known as o-hydroxybenzoic acid, is a white needle-like crystal or crystalline powder with a bitter taste, stable in air, difficult to dissolve in water, and easy to dissolve in organic solvents and boiling water. It is an important raw material of organic chemical industry, and is widely used in the fields of fine chemical industry such as food preservative, medicine, dye and perfume.

[0004] The industrial production of salicylic acid started late in China, in the late 1950s. At that time, the annual output of China was only two hundred tons per year. After that, with the promotion of industrialization in China, the production of salicylic acid entered an accelerated stage. At present, China is the largest producer of salicylic acid in the world.

[0005] The current domestic salicylic acid production process is as follows: phenol and concentrated sodium hydroxide are uniformly stirred in a container and then put into a multifunctional autoclave and heated to 130 DEG C for reaction; then dry sodium phenolate is obtained by vacuum evaporation; the high-pressure reaction kettle is put into cold water and quickly cooled to room temperature, and CO2 is slowly released, then deionized water is used as an absorption liquid, and then carboxylation is carried out to obtain a crude salicylic acid product; the crude product is dissolved in water, decolorized, filtered, and then sulfuric acid is added for acidification, and then separated, dried to obtain industrial salicylic acid.

[0006] The process has low reaction yield, inconvenient operation, and many reaction by-products, and also needs high-pressure equipment, so the production cost is high.

[0007] Therefore, a method for preparing salicylic acid by fixing carbon based on plasma is provided. SUMMARY

[0008] The purpose of the present application is to provide a method for preparing salicylic acid by fixing carbon based on plasma, which aims to solve the technical problems of high cost of salicylic acid preparation device in the prior art, and difficult water removal, poor dispersion state of raw materials, high temperature and high pressure, high energy consumption, use of corrosive reagents, and too much waste liquid and waste residue in the production process, and difficult post-treatment.

[0009] The application achieves the above-mentioned purpose by the following technical scheme: a method for carbon fixation into salicylic acid based on plasma, comprising the following steps:

[0010] argon gas with a first preset flow rate is introduced into the discharge reaction cavity, a positive high-voltage direct-current power supply is used to apply a preset voltage to the tip of the corona discharge needle, water vapor in the corona ionization cavity is ionized to generate non-adiabatic plasma;

[0011] then, high-purity argon gas containing benzene vapor with a second preset flow rate is introduced into the discharge reaction cavity, neutral benzene molecules react with the non-adiabatic plasma to generate phenol radical cations and hydrogen;

[0012] finally, carbon dioxide gas with a third preset flow rate is introduced into the discharge reaction cavity, the gas flow direction is located behind the intersection point of the first preset flow rate and the second preset flow rate, and the phenol radical cations react to form salicylic acid.

[0013] Compared with the prior art, the method for preparing salicylic acid provided by the application has the advantages of simple device, mild preparation conditions, high safety, energy saving and environmental protection, and mainly does not need to use corrosive reagents and has few by-products.

[0014] According to an aspect of the above technical scheme, the non-adiabatic plasma includes water cluster radical cations with high chemical reactivity, i.e., (H2O) n ·+ ion.

[0015] According to an aspect of the above technical scheme, the first preset flow rate is 100 mL / min-400 mL / min.

[0016] According to an aspect of the above technical scheme, the curvature radius of the tip of the discharge needle is 0.01 mm-0.1 mm.

[0017] According to an aspect of the above technical scheme, the second preset flow rate is 100 mL / min-400 mL / min.

[0018] According to an aspect of the above technical scheme, the third preset flow rate is 100 mL / min-1 L / min.

[0019] According to an aspect of the above technical scheme, the preset voltage is +1.0 kV-+8.0 kV.

[0020] According to an aspect of the above technical solution, the counter electrode can be an electrode at the inlet of a mass spectrometer, that is, the method of the application is coupled with a mass spectrometer, and after the three gas flows of preset flow rates intersect and converge, the gas flow containing product ions enters the ion transmission channel of the mass spectrometer, and then is detected by the mass analyzer of the mass spectrometer, so that the preparation process of salicylic acid can be monitored online.

[0021] According to an aspect of the above technical solution, the counter electrode can be conductive glass (such as I TO, FTO, etc.), and after the three gas flows of preset flow rates intersect and converge, the gas flow containing product ions is enriched on the counter electrode (the conductive glass) under the action of the corona electric field, and water or other absorption solvents for enriching salicylic acid are arranged on the conductive glass.

[0022] The application has the following beneficial effects:

[0023] The application can solve the technical problems in the prior art, such as high cost of a salicylic acid preparation device, difficulty in water removal in a production process, poor dispersion state of raw materials, high temperature and high pressure, high energy consumption, use of corrosive reagents, too much waste liquid and waste residue, and difficulty in post-processing. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A flow chart of the method for preparing salicylic acid in the application;

[0025] Figure 2 A first mass spectrum scan graph of the preparation of non-adiabatic plasma under a corona discharge, a first mass spectrum scan graph of the reaction of non-adiabatic plasma with neutral benzene, and a first mass spectrum scan graph of the reaction of generated phenol radical cations with carbon dioxide;

[0026] Figure 3 A high-performance liquid chromatogram of benzene, phenol and salicylic acid standard products, and a high-performance liquid chromatogram of an absorption liquid after the product in the application is enriched on the conductive glass (counter electrode) with water as the product absorption solvent. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0028] A method for preparing salicylic acid based on plasma carbon sequestration, comprising the following steps:

[0029] Step S1, a first preset flow rate and a preset humidity of argon gas are introduced into the discharge reaction cavity. Specifically, the first preset flow rate is 100 mL / min-400 mL / min.

[0030] A preset voltage is applied to the tip of the corona discharge needle to form a non-adiabatic plasma by water vapor corona discharge. The non-adiabatic plasma includes (H2O)2+ ions and (H2O) n ·+ ions and the like. Please refer to Figure 2 (a), the mass spectrum scan diagram of the non-adiabatic plasma prepared under the corona discharge shows that the non-adiabatic plasma includes (H2O)2 ·+ (m / z 36), (H2O)3 ·+ (m / z 54), H + (H2O)2(m / z 37), H + (H2O)3(m / z 55), H + (H2O)4(m / z 73), H + (H2O)5(m / z 91) plasma, hot electrons and excited state argon atoms. The (H2O) n ·+ ions are highly active and can react with substances in contact with them.

[0031] Under atmospheric pressure, the non-adiabatic plasma is prepared by low-energy corona discharge to convert water vapor into highly active (H2O)2 ·+ ions, and the reaction conditions are simple, safe, less polluting and energy-saving.

[0032] In addition, the preset voltage is +1.0 kV to +8.0 kV.

[0033] Step S2, a second preset flow rate of argon gas containing benzene vapor is introduced into the discharge reaction cavity to react with the (H2O)2 ·+ active ions to form phenol radical cations and release hydrogen.

[0034] Specifically, the second preset flow rate is 100 mL / min-400 mL / min. Please refer to Figure 2 (b), the mass spectrum scan diagram of the gas-phase molecular-ion reaction between (H2O)2 ·+ and benzene vapor shows that phenol radical cations can be formed after the reaction.

[0035] Step S3, a third preset flow rate of carbon dioxide gas is introduced, which is located behind the intersection point of the first preset flow rate and the second preset flow rate, so that the phenol radical cations generated by the first preset flow rate and the second preset flow rate react with carbon dioxide.

[0036] Specifically, the third preset flow rate is 100 mL / min-1 L / min. Please refer to Figure 2 (c), the first mass spectrum scan diagram of the gas phase molecule-ion reaction of phenol radical cation and carbon dioxide shows that salicylic acid radical cation can be formed after the reaction.

[0037] The product-enriched absorption liquid is collected, and high performance liquid chromatography is performed, and compared with the standard products of benzene, phenol and salicylic acid, so as to further prove that the salicylic acid can be efficiently prepared.

[0038] In an atmospheric environment, a non-adiabatic plasma is prepared by low-energy corona discharge, and water vapor is converted into high-activity (H2O)2 ·+ ions, benzene vapor is introduced into the channel to form phenol radical cation, and then carbon dioxide gas is introduced to prepare salicylic acid, which has the advantages of mild conditions, low energy consumption, simple equipment structure, convenient use and high safety, especially without using strong corrosive acid reagents, and less by-products.

[0039] Example 1

[0040] The first embodiment of the present application provides a method for preparing salicylic acid, which comprises steps S1-S3:

[0041] Step S1, a first preset flow rate of high-purity argon is introduced into the discharge reaction cavity, a preset voltage is applied to the tip of the discharge needle by means of a direct-current positive high-voltage power supply, an electric field is formed, water vapor is corona discharged to form a non-adiabatic plasma containing water cluster radical cations.

[0042] Specifically, the first preset flow rate is 100 mL / min, and the preset voltage is +5.5 kV.

[0043] Step S2, the second preset flow rate is 100 mL / min.

[0044] Step S3, a third preset flow rate of carbon dioxide gas is introduced into the discharge reaction cavity from the direction, and reacts with the phenol radical cation in the non-adiabatic plasma to form salicylic acid.

[0045] Specifically, the third preset flow rate is 600 mL / min, and the ion transmission tube temperature is set to 150 DEG C.

[0046] Example 2

[0047] The method for preparing salicylic acid provided by the second embodiment of the present application is different from the method for preparing salicylic acid in the first embodiment.

[0048] The preset voltage is +3.0 kV.

[0049] Embodiment three

[0050] The method for preparing salicylic acid provided in the third embodiment of the present application is different from the method for preparing aniline in the first embodiment in that:

[0051] The preset voltage is +3.0 kV.

[0052] Embodiment four

[0053] The method for preparing salicylic acid provided in the fourth embodiment of the present application is different from the method for preparing salicylic acid in the first embodiment in that:

[0054] The preset voltage is +3.0 kV.

[0055] Embodiment five

[0056] The method for preparing salicylic acid provided in the fifth embodiment of the present application is different from the method for preparing salicylic acid in the first embodiment in that:

[0057] The preset voltage is +3.0 kV.

[0058] Embodiment six

[0059] The method for preparing salicylic acid provided in the sixth embodiment of the present application is different from the method for preparing salicylic acid in the first embodiment in that:

[0060] The preset voltage is +3.0 kV.

[0061] Please refer to Table 1 below, which shows the parameters corresponding to the above-mentioned embodiments one to six of the present application.

[0062] Table 1

[0063]

[0064] It should be noted that embodiments one to six are prepared under the corresponding process conditions, and tested by a mass spectrometer.

[0065] It can be known from the data of embodiments one to six that the non-adiabatic plasma is prepared by low-energy corona discharge, and the water vapor is converted into high-activity (H2O)2 ·+; and then introducing benzene vapor into the introduction channel to form phenol radical cations through molecular ion reaction; and finally introducing carbon dioxide into the rear end to convert it into salicylic acid. This method has the advantages of mild conditions, low energy consumption, simple structure, easy use, high safety, and can effectively solve the technical problems of complex device, high cost, large amount of waste and low yield in the prior art.

[0066] In combination with the data of Example One and Example Two, it can be known that, in consideration of energy consumption, the preset voltage applied to the corona discharge needle is +5.5 kV, and the efficiency of preparing salicylic acid is the highest.

[0067] In combination with the data of Example One and Example Three, it can be known that, unilateral increase of the gas flow rate of argon does not improve the efficiency of reaction to generate salicylic acid, and the first preset flow rate is 100 mL / min, and the efficiency of preparing salicylic acid is the highest.

[0068] In combination with the data of Example One and Example Four, it can be known that, unilateral increase of the content of benzene vapor slightly increases the yield of salicylic acid, but the increase of salicylic acid yield is limited, and it is not the optimal process condition, so the second preset flow rate is 100 mL / min, which is the preferred scheme for preparing salicylic acid.

[0069] In combination with the data of Example One and Example Five, it can be known that, unilateral increase of the content of carbon dioxide significantly increases the yield of salicylic acid and the efficiency of carbon sequestration, and the unconverted carbon dioxide can be reused. Therefore, the third preset flow rate is 1 L / min, which is the preferred scheme for preparing salicylic acid.

[0070] In combination with the data of Example One and Example Six, it can be known that, increasing the temperature of the reaction (the temperature of the ion transmission tube) forces the cleavage of water cluster radical cations, which is not conducive to the formation of salicylic acid precursors (phenol radical cations), so the temperature of the ion transmission tube is 150℃, which is the preferred scheme for preparing salicylic acid.

[0071] In addition, it should be understood that, although the present specification is described in terms of embodiments, each embodiment does not contain only one independent technical solution, and the description manner of the specification is only for the sake of clarity, and the person skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be combined to form other embodiments that can be understood by the person skilled in the art.

Claims

1. A method for converting carbon to salicylic acid based on plasma, characterized in that, Includes the following steps: S1. High-purity argon gas with a first preset flow rate is introduced. A preset DC positive high voltage is applied to the tip of the corona discharge needle through a high-voltage power supply, forming a strong corona electric field between the needle and the counter electrode, and forming non-insulated plasma by corona discharge of trace water vapor in the discharge reaction chamber. S2. High-purity argon gas containing benzene vapor is introduced at a second preset flow rate. Neutral benzene molecules react with the non-adiabatic plasma phase in step S1 to generate phenol radical cations and hydrogen gas. S3. Carbon dioxide gas at a third preset flow rate is introduced into the discharge reaction chamber, and the gas flow is located behind the intersection of the first preset flow rate gas flow and the second preset flow rate gas flow, and undergoes a molecular-ion reaction with the phenol free radical cation in step S2 to prepare salicylic acid.

2. The method for plasma-based carbon fixation to salicylic acid according to claim 1, characterized in that: The non-adiabatic plasma contains a large number of highly reactive water cluster free radical cations, namely: (H2O). n ·+ ion.

3. The method for plasma-based carbon fixation to salicylic acid according to claim 1, characterized in that: The first preset flow rate is 100ml / min-400ml / min.

4. The method for plasma-based carbon fixation to salicylic acid according to claim 1, characterized in that: The radius of curvature of the tip of the discharge needle is 0.01mm-0.1mm.

5. The method for plasma-based carbon fixation to salicylic acid according to claim 1, characterized in that: The second preset flow rate is 100 mL / min-400 mL / min.

6. The method for plasma-based carbon fixation to salicylic acid according to claim 1, characterized in that: The third preset flow rate is 100 mL / min - 1 L / min.

7. The method for plasma-based carbon fixation to salicylic acid according to claim 1, characterized in that: The preset voltage is +1.0kV to +8.0kV.

8. The method for plasma-based carbon fixation to salicylic acid according to claim 1, characterized in that: The counter electrode is the electrode at the inlet of the mass spectrometer. After the three preset flow rates of gas converge and react, the gas containing product ions enters the ion transmission channel of the mass spectrometer and is then detected by the mass analyzer of the mass spectrometer, allowing for online monitoring of the preparation process of salicylic acid.

9. The method for plasma-based carbon fixation to salicylic acid according to claim 1, characterized in that: The counter electrode is made of conductive glass. After the three preset flow rates of gas converge and react, the gas containing product ions is enriched on the counter electrode under the action of the corona electric field.

10. The method for plasma-based carbon fixation to salicylic acid according to claim 9, characterized in that: The conductive glass is provided with water or other absorbent solvents for enriching salicylic acid.

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