An alkaline spraying system for the production of ethyl chloroformate

Abstract

This invention relates to the field of spray system technology, and more particularly to an alkaline spray system for the production of ethyl chloroformate, comprising the following steps: S1, adding tetramethylammonium hydroxide to water, heating to room temperature, stirring until completely dissolved, adding modified sodium metasilicate, disodium ethylenediaminetetraacetate, and sodium lignosulfonate, controlling the temperature and stirring, filtering to obtain an alkaline solution; S2, turning on the power to the control system, ensuring the control system operates normally, setting the operating parameters of the spray system, starting the alkaline solution pump, drawing the alkaline solution from the storage tank, conveying it through pipelines to the spray heads, adjusting the pump's output flow rate, and starting intermittent, uniform spraying of the alkaline solution. The waste liquid after spraying flows through pipelines into a sedimentation tank for post-treatment. The alkaline spray system of this invention can significantly improve the purification efficiency of acidic gases, heavy metal ions, and organic pollutants in waste gas.

Description

Technical Field

[0001] This invention relates to the field of organic chemical technology, and in particular to an alkaline spraying system for the production of ethyl chloroformate. Background Technology

[0002] Ethyl chloroformate is an important organic chemical raw material with the chemical formula C3H5ClO2. It is a colorless, transparent liquid with a pungent odor. Ethyl chloroformate has wide applications in pesticides, pharmaceuticals, fragrances, and synthetic resins, and its market demand is increasing year by year with the rapid development of related industries. During the production of ethyl chloroformate, a certain amount of waste gas is generated, which may contain pollutants such as sulfides and carbon dioxide. To effectively control and reduce the emission of these pollutants, alkaline spray systems are widely used in the waste gas treatment stage of ethyl chloroformate production. The working principle of the alkaline spray system is to spray an alkaline liquid into the exhaust gas pipeline. Through a chemical reaction between the alkaline liquid and the pollutants in the waste gas, the pollutants are converted into non-volatile salts, thereby reducing the concentration of pollutants in the waste gas and achieving the purpose of purifying the waste gas.

[0003] In existing technologies, alkaline spray systems suffer from uneven spraying, resulting in some waste gas failing to fully contact the alkaline solution, thus affecting the purification effect. Furthermore, the liquid-to-gas ratio of the spray system is low, which may prevent the system from fully absorbing pollutants in the waste gas, especially when the waste gas concentration is high or the flow rate is large, potentially leading to a significant decrease in purification efficiency. Summary of the Invention

[0004] To address the problems mentioned in the background section, the present invention provides an alkaline spraying system for the production of ethyl chloroformate.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An alkaline spraying system for the production of ethyl chloroformate includes the following steps:

[0007] S1. Add tetramethylammonium hydroxide to water, heat to room temperature, stir until completely dissolved, add modified sodium metasilicate, disodium ethylenediaminetetraacetate and sodium lignosulfonate, control the temperature, stir for 30-60 min, filter with a 0.45 μm filter to obtain alkaline solution;

[0008] S2. Turn on the power to the control system to ensure its normal operation. Set the operating parameters of the spray system, start the alkali pump to extract the alkali from the storage tank and transport it to the spray head through the pipeline. Adjust the pump's output flow rate and start intermittently and evenly spraying the alkali. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment.

[0009] Further, in step S1, the mass ratio of tetramethylammonium hydroxide, water, modified sodium metasilicate, disodium ethylenediaminetetraacetate, and sodium lignosulfonate is (2-3):1000:(1-1.5):(0.3-0.5):(0.2-0.3).

[0010] Furthermore, in step S1, the temperature is controlled at 40-50℃ and the stirring speed is 50-100rpm.

[0011] Furthermore, the modified sodium metasilicate in step S1 is prepared by the following steps:

[0012] Sodium metasilicate was added to water and heated to 55-60℃. The mixture was stirred until completely dissolved. Acrylic acid was added and stirring was continued for 30-40 minutes. Ammonium persulfate was added and the pH was adjusted to 7-8. The mixture was kept at 55-60℃ in a constant temperature water bath for 4-6 hours. After the reaction was completed, the mixture was filtered and washed to obtain modified sodium metasilicate.

[0013] Furthermore, the specific operating parameters of the spray system in step S2 are as follows: the spray flow rate of the alkaline solution is 20-30 L / min, and the pressure of the spray system is 0.3-0.4 MPa.

[0014] Furthermore, in step S2, the pump's output flow rate is 25-28 L / min.

[0015] Furthermore, in step S2, the intermittent spraying is specifically defined as follows: the duration of each spraying session is 10-15 minutes, and the interval between two spraying sessions is 5 minutes.

[0016] Furthermore, the mass ratio of sodium metasilicate, water, acrylic acid, and ammonium persulfate is (10-12):50:(2-4):(0.08-0.1).

[0017] The beneficial effects of this invention are:

[0018] 1. In the technical solution of this invention, the alkaline solution is composed of tetramethylammonium hydroxide (TMAH), water, modified sodium metasilicate, disodium ethylenediaminetetraacetate (EDTA-2Na), and sodium lignosulfonate, forming a stable suspension or solution. TMAH completely ionizes in water into tetramethylammonium ions and hydroxide ions, serving as the main active components in the neutralization reaction. Modified sodium metasilicate introduces carboxyl and hydroxyl groups through acrylic acid polymerization, enhancing its chelating ability and dispersing properties. EDTA-2Na, with its strong chelating ability, forms stable complexes with metal ions. Sodium lignosulfonate, as a natural polymeric surfactant, provides good dispersibility and wetting properties.

[0019] 2. In the technical solution of this invention, the hydroxide ions provided by TMAH enable the alkaline solution to have a highly efficient neutralization capacity, rapidly reacting with acidic substances in the waste gas to generate salt and water, thereby effectively reducing the concentration of acidic substances in the waste gas. Secondly, the strong chelating ability of EDTA-2Na ensures that heavy metal ions in the waste gas can be effectively removed, forming stable complexes and preventing their accumulation in the environment. Furthermore, the carboxyl and hydroxyl functional groups of modified sodium metasilicate and sodium lignosulfonate endow the alkaline solution with excellent dispersibility and adsorption properties, enabling the transfer of organic pollutants in the waste gas from the gas phase to the liquid phase and fixing them on the surface of the alkaline solution through adsorption. Finally, the synergistic effect between the components further improves the purification efficiency of the alkaline solution. The neutralization reaction of TMAH creates favorable conditions for the adsorption and complexation of other components, while the removal of heavy metal ions by EDTA-2Na reduces interference with other components. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specified, the raw materials used in this invention are all from commercially available conventional products.

[0022] Preparation Example 1

[0023] Modified sodium metasilicate is prepared by the following steps:

[0024] Add 10 kg of sodium metasilicate to 50 kg of water, heat to 55 °C, stir until completely dissolved, add 2 kg of acrylic acid, continue stirring for 30 min, add 0.08 kg of ammonium persulfate, adjust the pH to 7, maintain at 55 °C in a constant temperature water bath, and react for 4 h. After the reaction is complete, filter and wash to obtain modified sodium metasilicate.

[0025] Preparation Example 2

[0026] Modified sodium metasilicate is prepared by the following steps:

[0027] 11 kg of sodium metasilicate was added to 50 kg of water, heated to 58 °C, and stirred until completely dissolved. 3 kg of acrylic acid was added, and stirring was continued for 35 min. 0.09 kg of ammonium persulfate was added, and the pH was adjusted to 7.5. The mixture was kept at 58 °C in a constant temperature water bath for 5 h. After the reaction was completed, the mixture was filtered and washed to obtain modified sodium metasilicate.

[0028] Preparation Example 3

[0029] Modified sodium metasilicate is prepared by the following steps:

[0030] Add 12 kg of sodium metasilicate to 50 kg of water, heat to 60 °C, stir until completely dissolved, add 4 kg of acrylic acid, continue stirring for 40 min, add 0.1 kg of ammonium persulfate, adjust the pH to 8, maintain 60 °C in a constant temperature water bath, and react for 6 h. After the reaction is complete, filter and wash to obtain modified sodium metasilicate.

[0031] Example 1

[0032] An alkaline spraying system for the production of ethyl chloroformate includes the following steps:

[0033] S1. Add 2 kg of tetramethylammonium hydroxide to 1000 kg of water, heat to room temperature, stir until completely dissolved, add 1 kg of modified sodium metasilicate prepared in Preparation Example 1, 0.3 kg of disodium ethylenediaminetetraacetate and 0.2 kg of sodium lignosulfonate, control the temperature at 40°C, stir at 50 rpm for 30 min, filter with a 0.45 μm filter to obtain an alkaline solution;

[0034] S2. Turn on the power to the control system and ensure that the control system is operating normally. Set the operating parameters of the spray system: the spray flow rate of the alkali solution is 20-30 L / min, the pressure of the spray system is 0.3 MPa, start the alkali solution pump to draw the alkali solution from the storage tank and transport it to the spray head through the pipeline. Adjust the output flow rate of the pump to 25 L / min and start intermittently and uniformly spraying the alkali solution. The duration of each spray is 10 minutes, and the interval between two sprays is 5 minutes. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment.

[0035] Example 2

[0036] An alkaline spraying system for the production of ethyl chloroformate includes the following steps:

[0037] S1. Add 2.2 kg of tetramethylammonium hydroxide to 1000 kg of water, heat to room temperature, stir until completely dissolved, add 1.1 kg of modified sodium metasilicate prepared in Preparation Example 2, 0.32 kg of disodium ethylenediaminetetraacetate and 0.22 kg of sodium lignosulfonate, control the temperature at 42°C, stir at 50 rpm for 35 min, filter with a 0.45 μm filter to obtain an alkaline solution;

[0038] S2. Turn on the power to the control system and ensure its normal operation. Set the operating parameters of the spray system: the spray flow rate of the alkali solution is 22 L / min, and the pressure of the spray system is 0.31 MPa. Start the alkali solution pump to extract the alkali solution from the storage tank and transport it to the spray head through the pipeline. Adjust the pump output flow rate to 25.5 L / min and start intermittently and uniformly spraying the alkali solution. The duration of each spray is 12 minutes, and the interval between two sprays is 5 minutes. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment.

[0039] Example 3

[0040] An alkaline spraying system for the production of ethyl chloroformate includes the following steps:

[0041] S1. Add 2.5 kg of tetramethylammonium hydroxide to 1000 kg of water, heat to room temperature, stir until completely dissolved, add 1.2 kg of modified sodium metasilicate prepared in Preparation Example 3, 0.34 kg of disodium ethylenediaminetetraacetate and 0.23 kg of sodium lignosulfonate, control the temperature at 45°C, stir at 60 rpm for 40 min, filter with a 0.45 μm filter to obtain an alkaline solution;

[0042] S2. Turn on the power to the control system and ensure its normal operation. Set the operating parameters of the spray system: the spray flow rate of the alkali solution is 25 L / min, and the pressure of the spray system is 0.34 MPa. Start the alkali solution pump to extract the alkali solution from the storage tank and transport it to the spray head through the pipeline. Adjust the pump output flow rate to 26 L / min and start intermittently and uniformly spraying the alkali solution. The duration of each spray is 13 minutes, and the interval between two sprays is 5 minutes. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment.

[0043] Example 4

[0044] An alkaline spraying system for the production of ethyl chloroformate includes the following steps:

[0045] S1. Add 2.6 kg of tetramethylammonium hydroxide to 1000 kg of water, heat to room temperature, stir until completely dissolved, add 1.4 kg of modified sodium metasilicate prepared in Preparation Example 1, 0.4 kg of disodium ethylenediaminetetraacetate and 0.28 kg of sodium lignosulfonate, control the temperature at 45°C, stir at 80 rpm for 45 min, filter with a 0.45 μm filter to obtain an alkaline solution;

[0046] S2. Turn on the power to the control system and ensure its normal operation. Set the operating parameters of the spray system: the spray flow rate of the alkali solution is 25 L / min, and the pressure of the spray system is 0.37 MPa. Start the alkali solution pump to extract the alkali solution from the storage tank and transport it to the spray head through the pipeline. Adjust the pump output flow rate to 27 L / min and start intermittently and uniformly spraying the alkali solution. The duration of each spray is 14 min, and the interval between two sprays is 5 min. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment.

[0047] Example 5

[0048] An alkaline spraying system for the production of ethyl chloroformate includes the following steps:

[0049] S1. Add 3 kg of tetramethylammonium hydroxide to 1000 kg of water, heat to room temperature, stir until completely dissolved, add 1.5 kg of modified sodium metasilicate prepared in Preparation Example 2, 0.5 kg of disodium ethylenediaminetetraacetate and 0.3 kg of sodium lignosulfonate, control the temperature at 50°C, stir at 100 rpm for 60 min, filter with a 0.45 μm filter to obtain an alkaline solution;

[0050] S2. Turn on the power to the control system and ensure its normal operation. Set the operating parameters of the spray system: the spray flow rate of the alkali solution is 30L / min, and the pressure of the spray system is 0.4MPa. Start the alkali solution pump to extract the alkali solution from the storage tank and transport it to the spray head through the pipeline. Adjust the pump output flow rate to 28L / min and start intermittently and uniformly spraying the alkali solution. The duration of each spray is 15 minutes, and the interval between two sprays is 5 minutes. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment.

[0051] Comparative Example 1

[0052] The difference between this comparative example and Example 1 is that tetramethylammonium hydroxide is not added; the remaining steps are the same as in Example 1.

[0053] Comparative Example 2

[0054] The difference between this comparative example and Example 2 is that modified sodium metasilicate is not added; the remaining steps are the same as in Example 2.

[0055] Comparative Example 3

[0056] The difference between this comparative example and Example 3 is that disodium ethylenediaminetetraacetate is not added; the remaining steps are the same as in Example 3.

[0057] Comparative Example 4

[0058] The difference between this comparative example and Example 4 is that sodium lignosulfonate is not added; the remaining steps are the same as in Example 4.

[0059] Comparative Example 5

[0060] The difference between this comparative example and Example 5 is that a 30% sodium hydroxide solution is used instead of an alkaline solution; the remaining steps are the same as in Example 5.

[0061] The concentrations of acidic gases, heavy metal ions, and organic pollutants in the exhaust gases before and after treatment in Examples 1-5 and Comparative Examples 1-5 were determined using chemical analysis methods. Gas chromatography was used to determine the concentration of acidic gases. Atomic absorption spectrometry was used to determine the concentration of heavy metal ions. High-performance liquid chromatography was used to determine the concentration of organic pollutants. The purification efficiency of each example and comparative example was calculated as: Purification efficiency = (Concentration before treatment - Concentration after treatment) / Concentration before treatment × 100%. The results are shown in Table 1.

[0062] Table 1. Purification efficiency results of Examples 1-5 and Comparative Examples 1-5

[0063]

[0064]

[0065] Table 1 shows that the acid gas purification efficiencies of Examples 1-5 are generally high, all above 90%. This is likely due to the synergistic effect of tetramethylammonium hydroxide and modified sodium metasilicate in the alkaline solution. Tetramethylammonium hydroxide is a strong base that can effectively neutralize acid gases, while modified sodium metasilicate may increase the adsorption and reactivity of the alkaline solution for acid gases through its special chemical structure. In Comparative Example 1, without the addition of tetramethylammonium hydroxide, the purification efficiency decreased (85.7%). This indicates that tetramethylammonium hydroxide has a significant neutralizing effect on acid gases in the alkaline system. In Comparative Example 2, without the addition of modified sodium metasilicate, the purification efficiency also decreased (87.4%). This indicates that modified sodium metasilicate plays an important role in enhancing the purification capacity of the alkaline solution for acid gases. Although the purification efficiency of Comparative Examples 3-5 was slightly lower than that of the Examples, it was higher than that of Comparative Examples 1 and 2, indicating that components such as disodium ethylenediaminetetraacetate and sodium lignosulfonate also contributed to the purification of acidic gases, but not as significantly as tetramethylammonium hydroxide and modified sodium metasilicate.

[0066] Examples 1-5 all showed high purification efficiencies for heavy metal ions, and the purification efficiency showed a slight upward trend with the increase of modified sodium metasilicate (Examples 1-5), possibly because the special structure of modified sodium metasilicate has a strong adsorption capacity for heavy metal ions. Comparative Example 2, without the addition of modified sodium metasilicate, showed a significant decrease in purification efficiency (81.2%), indicating the key role of modified sodium metasilicate in heavy metal ion purification. Although the purification efficiencies of other comparative examples were slightly lower than those of the examples, they were all higher than those of Comparative Example 2, indicating that components such as tetramethylammonium hydroxide, disodium ethylenediaminetetraacetate, and sodium lignosulfonate also contributed to the purification of heavy metal ions.

[0067] The purification efficiency of organic pollutants in Examples 1-5 increased with the increase of modified sodium metasilicate, reaching its highest level (84.7%) in Example 4. This may be because modified sodium metasilicate not only has a purification effect on acidic gases and heavy metal ions, but also has a certain adsorption or degradation capacity for organic pollutants. In Comparative Example 4, without the addition of sodium lignosulfonate, the purification efficiency decreased (77.1%). Sodium lignosulfonate may enhance the dispersion and degradation capacity of the alkaline solution for organic pollutants through its surface activity. Comparative Example 5, using 30% sodium hydroxide solution instead of alkaline solution, had the lowest purification efficiency (70.9%). This indicates that the alkaline solution designed in this experiment is significantly superior to a single strong alkaline solution in purifying organic pollutants.

[0068] In summary, the alkaline spraying systems of Examples 1-5 can significantly improve the purification efficiency of acidic gases, heavy metal ions, and organic pollutants in exhaust gas.

[0069] In the description of this specification, the reference to terms such as "example," "various examples," etc., means that a specific feature, structure, material, or characteristic described in connection with that example or preparation is included in at least one example or preparation of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same example or preparation. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more examples or preparations.

[0070] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An alkaline spraying system for the production of ethyl chloroformate, characterized in that, Includes the following steps: S1. Add tetramethylammonium hydroxide to water, heat to room temperature, stir until completely dissolved, add modified sodium metasilicate, disodium ethylenediaminetetraacetate and sodium lignosulfonate, control the temperature, stir for 30-60 min, filter with a 0.45 μm filter to obtain alkaline solution; S2. Start the alkali pump to extract the alkali from the storage tank and transport it to the spray head through the pipeline. Adjust the pump output flow rate and start intermittently and evenly spraying the alkali. The waste liquid after spraying flows into the sedimentation tank through the pipeline for post-treatment. The modified sodium metasilicate in step S1 is prepared by the following steps: Sodium metasilicate was added to water and heated to 55-60℃. The mixture was stirred until completely dissolved. Acrylic acid was added and stirring was continued for 30-40 minutes. Ammonium persulfate was added and the pH was adjusted to 7-8. The mixture was kept at 55-60℃ in a constant temperature water bath for 4-6 hours. After the reaction was completed, the mixture was filtered and washed to obtain modified sodium metasilicate.

2. The alkaline spraying system for producing ethyl chloroformate according to claim 1, characterized in that, In step S1, the mass ratio of tetramethylammonium hydroxide, water, modified sodium metasilicate, disodium ethylenediaminetetraacetate, and sodium lignosulfonate is (2-3):1000:(1-1.5):(0.3-0.5):(0.2-0.3).

3. The alkaline spraying system for producing ethyl chloroformate according to claim 1, characterized in that, In step S1, the temperature is controlled at 40-50℃ and the stirring speed is 50-100rpm.

4. The alkaline spraying system for producing ethyl chloroformate according to claim 1, characterized in that, The specific operating parameters of the spray system in step S2 are as follows: the spray flow rate of the alkaline solution is 20-30 L / min, and the pressure of the spray system is 0.3-0.4 MPa.

5. The alkaline spraying system for producing ethyl chloroformate according to claim 1, characterized in that, In step S2, the pump output flow rate is 25-28 L / min.

6. The alkaline spraying system for producing ethyl chloroformate according to claim 1, characterized in that, In step S2, the intermittent spraying is specifically defined as follows: the duration of each spraying session is 10-15 minutes, and the interval between two spraying sessions is 5 minutes.

7. The alkaline spraying system for producing ethyl chloroformate according to claim 1, characterized in that, The mass ratio of sodium metasilicate, water, acrylic acid, and ammonium persulfate is (10-12):50:(2-4):(0.08-0.1).

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