A composite desulfurizer for removing SO2, NO x and HCl and a method for preparing the same

Abstract

The present application belongs to the technical field of adsorption desulfurizer, and specifically provides a composite desulfurizer for removing SO2, NO X and HCl and a preparation method thereof. The composite desulfurizer comprises the following components in parts by weight: desulfurizer 25-35 parts, denitration agent 30-50 parts, and modified activated carbon 10-15 parts. The composite desulfurizer can simultaneously and efficiently remove SO2, NO X and HCl, effectively solves the problem that traditional single desulfurizer can only target one pollutant, significantly improves the desulfurization efficiency, meets the increasingly stringent environmental protection requirements, has good renewability, reduces the desulfurization cost, reduces the generation of waste, meets the requirements of environmental protection and sustainable development, and can be used in high-temperature environments and is suitable for use in waste incineration plants.

Description

Technical Field

[0001] This invention belongs to the field of adsorption desulfurization agent technology, specifically relating to a method for removing SO2 and NO. X A composite desulfurizing agent containing HCl and its preparation method. Background Technology

[0002] With the acceleration of industrialization, the pollution problem caused by flue gas emissions has become increasingly serious, including sulfur dioxide (SO₂) and nitrogen oxides (NO₂). x SO2 and hydrogen chloride (HCl) are the main pollutants. Waste incineration has become the primary method of municipal solid waste treatment in my country. Municipal solid waste contains a large amount of organic matter and generally contains sulfur, chlorine, and nitrogen. During combustion, these substances decompose under heat and undergo intense high-temperature oxidation, releasing air pollutants. However, traditional desulfurization, denitrification, and dechlorination technologies mostly treat single pollutants, resulting in low efficiency, high cost, and secondary pollution. In recent years, multi-pollutant synergistic removal technology has gradually attracted attention, aiming to develop a method that can simultaneously and efficiently remove SO2 and NO2. x A composite desulfurizing agent with HCl.

[0003] Chinese patent CN 107297144 B discloses a composite desulfurizing agent, which, by weight percentage, contains 1-15% cyanuric acid, 1-15% cosolvent, 1-20% catalyst, 0-10% chelating agent, 1-20% stabilizer, and 50-95% water. This composite desulfurizing agent is inexpensive, readily available, and can achieve efficient desulfurization and denitrification. However, the components such as water and ethylenediamine, the chelating agent, are easily decomposed and volatilized at high temperatures, making it unsuitable for flue gas treatment in the waste incineration industry.

[0004] Therefore, there is an urgent need to develop a new type of composite desulfurizing agent and its preparation method, which aims to achieve high efficiency in the synergistic removal of multiple air pollutants under high temperature conditions, while also having economic and environmental benefits. Summary of the Invention

[0005] To address the existing technical problems, the purpose of this invention is to provide a method for removing SO2 and NO. X A composite desulfurizing agent containing SO2 and HCl, and its preparation method. The composite desulfurizing agent of this invention can simultaneously and efficiently remove SO2 and NO. X The composite desulfurizer, combined with HCl, effectively solves the problem that traditional single desulfurizers can only target one type of pollutant, significantly improving desulfurization efficiency and meeting increasingly stringent environmental protection requirements. Furthermore, the composite desulfurizer of this invention has good regenerability; the used desulfurizer can be regenerated through simple heat treatment or chemical treatment and reused, reducing desulfurization costs and waste generation, thus meeting environmental protection and sustainable development requirements. Moreover, the composite desulfurizer can be used in high-temperature environments and is suitable for use in waste incineration plants.

[0006] This invention provides a method for removing SO2 and NO. X The composite desulfurizing agent containing HCl comprises, by weight, the following components: 25-35 parts desulfurizing agent, 30-50 parts denitrifying agent, and 10-15 parts modified activated carbon.

[0007] The reaction mechanism and function of this invention are as follows:

[0008] 1. The desulfurizing agent of this invention employs a composition of calcium hydroxide, calcium carbonate, and calcium sulfate, which can effectively reduce the emission of pollutants such as sulfur dioxide, nitrogen oxides, and hydrogen chloride, thus benefiting environmental protection. Calcium hydroxide and calcium carbonate are commonly used desulfurizing agents; their combined use can effectively improve desulfurization efficiency and reduce costs. The introduction of calcium sulfate can effectively improve the strength of the product, thereby enhancing the stability and renewability of the composite desulfurizing agent and reducing subsequent processing costs. Furthermore, the applicant has discovered that mixing calcium sulfate with calcium hydroxide and calcium carbonate improves nitrogen removal efficiency.

[0009] 2. The present invention can improve the calcium conversion rate by adding a small amount of magnesium oxide to the calcium-based desulfurizer, thereby improving the removal of acidic gases. This may be because the presence of magnesium oxide provides a supporting framework and better maintains the pore structure.

[0010] 3. Montmorillonite has a layered structure with large interlayer spacing, providing additional adsorption sites. Organic modification of montmorillonite by adding dimethylaminoethyl methacrylate and dodecyltrimethylammonium bromide further expands the interlayer spacing, increasing adsorption capacity. Simultaneously, the addition of dodecyltrimethylammonium bromide enhances the hydrophobicity of montmorillonite, reducing water molecule adsorption. This hydrophobicity improves the stability of activated carbon under high humidity conditions, reducing the impact of water poisoning and further enhancing the water poisoning resistance of activated carbon. Furthermore, this invention improves the adsorption performance and stability by intercalating titanium dioxide into montmorillonite to improve its dispersibility. Moreover, the double bonds introduced on the titanium dioxide / montmorillonite composite material can be grafted onto coconut shell activated carbon via the double bonds on 3-vinyl-1-(2-propen-1-yl)-1H-imidazolium tetrafluoroborate, ensuring stable adhesion of the titanium dioxide / montmorillonite composite material to the activated carbon. This not only reduces the possibility of activated carbon pore collapse during regeneration but also reduces SO2 and NO... X Furthermore, van der Waals forces exist between HCl molecules and molecules on the surface of titanium dioxide particles. When the molecules on the titanium dioxide surface are heated, the adsorbed SO2 and NO... X Furthermore, HCl molecules can be desorbed from titanium dioxide, thus improving the desulfurization, denitrification, dechlorination performance, and regeneration function of modified activated carbon.

[0011] In some embodiments, the desulfurizing agent is a combination of calcium hydroxide, calcium carbonate, and calcium sulfate.

[0012] In some embodiments, the mass ratio of calcium hydroxide, calcium carbonate, and calcium sulfate is 10:(9.5-10.5):(0.08-0.2).

[0013] Preferably, the particle size of the desulfurizing agent is 150-300 mesh.

[0014] In some embodiments, the denitrifying agent comprises any one or more of urea, polyaniline, and polyamide.

[0015] In some embodiments, the method for preparing the modified activated carbon includes the following steps:

[0016] Q1. Mix sodium-based montmorillonite with deionized water, stir, adjust the pH of the dispersion to 4.5-5.5, add dimethylaminoethyl methacrylate and dodecyltrimethylammonium bromide, heat to 60-80℃ and react for 1-1.5h, cool, filter under reduced pressure to obtain solid, dry, grind, and obtain pretreated montmorillonite;

[0017] Q2. Mix tetrabutyl titanate and aqueous ethanol solution, stir, add the pretreated montmorillonite obtained in step Q1, heat to 60-80℃ and stir to react for 2-4 hours, cool, wash and dry to obtain titanium dioxide / montmorillonite composite material.

[0018] Q3. Mix coconut shell activated carbon with deionized water, stir, add 3-vinyl-1-(2-propen-1-yl)-1H-imidazolium tetrafluoroborate and N,N-dimethylformamide, heat to 50-70℃ and stir for 20-30h, then add the titanium dioxide / montmorillonite composite material obtained in step Q2 and the initiator, and react at 60-80℃ under inert gas protection, cool, wash, filter and dry to obtain modified activated carbon.

[0019] In some embodiments, the mass ratio of sodium montmorillonite, dimethylaminoethyl methacrylate, and dodecyltrimethylammonium bromide in step Q1 is 10:(0.5-0.7):(0.35-0.55).

[0020] In some embodiments, the mass ratio of the pretreated montmorillonite to tetrabutyl titanate in step Q2 is 1:(0.5-1).

[0021] In some embodiments, the mass ratio of 3-vinyl-1-(2-propen-1-yl)-1H-imidazolium tetrafluoroborate, coconut shell activated carbon, and titanium dioxide / montmorillonite composite material in step Q3 is (14-18):(400-600):1.

[0022] In some embodiments, the composite desulfurizing agent further comprises 4-6 parts by weight of magnesium oxide.

[0023] Another aspect of the present invention is to provide a method for removing SO2 and NO as described above. X The preparation method of the composite desulfurizing agent containing HCl includes the following steps:

[0024] A composite desulfurizing agent is obtained by mixing desulfurizing agent, denitrifying agent, and modified activated carbon.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. The composite desulfurizing agent of the present invention can simultaneously and efficiently remove SO2 and NO. X The addition of HCl effectively solves the problem that traditional single desulfurizing agents can only target one type of pollutant, significantly improving desulfurization efficiency and meeting increasingly stringent environmental protection requirements. Furthermore, the composite desulfurizing agent of this invention has excellent renewability, reducing desulfurization costs and waste generation, thus meeting the requirements of environmental protection and sustainable development. Moreover, the composite desulfurizing agent can be used in high-temperature environments and is suitable for use in waste incineration plants.

[0027] Traditional desulfurization processes, such as semi-dry, dry, and wet desulfurization, treat pollutants after they are generated, which is costly and produces a large amount of fly ash. However, the composite desulfurizing agent of this invention can be used in the front-end control of pollutant generation, replacing traditional processes and eliminating traditional desulfurization systems and activated carbon systems, thereby effectively reducing fly ash by nearly 50%.

[0028] 2. The desulfurizing agent of the present invention is a combination of calcium hydroxide, calcium carbonate and calcium sulfate, which can effectively reduce the emission of pollutants such as sulfur dioxide, nitrogen oxides and hydrogen chloride, thus benefiting environmental protection.

[0029] 3. The magnesium oxide of the present invention can improve the calcium conversion rate, thereby enhancing the removal of acidic gases.

[0030] 4. This invention, on the one hand, increases the adsorption capacity by further expanding the interlayer spacing of montmorillonite through the addition of dimethylaminoethyl methacrylate and dodecyltrimethylammonium bromide; simultaneously, the pretreated montmorillonite exhibits better hydrophobicity, improving the water-toxicity resistance of activated carbon. On the other hand, intercalating titanium dioxide into montmorillonite improves its dispersibility, thereby enhancing its adsorption performance and stability. Furthermore, the titanium dioxide / montmorillonite composite material can be grafted onto coconut shell activated carbon, reducing the possibility of activated carbon pore collapse during regeneration and improving the desulfurization, denitrification, dechlorination performance, and regeneration function of the modified activated carbon. Detailed Implementation

[0031] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0032] Each composite desulfurizer was prepared according to the proportions and preparation methods of the raw materials specified in the following examples and comparative examples.

[0033] To facilitate implementation of this invention by those skilled in the art, the manufacturers of some raw materials for the embodiments and comparative examples are described below:

[0034] The desulfurizing agents calcium hydroxide, calcium carbonate, and calcium sulfate all have a particle size of 200 mesh.

[0035] Coconut shell activated carbon: purchased from Henan Yutai Environmental Protection Materials Co., Ltd., model YT-19;

[0036] Unless otherwise specified, all other raw materials can be purchased from the market.

[0037] Preparation Example 1

[0038] The preparation method of modified activated carbon A includes the following steps:

[0039] Q1. Mix 200g sodium montmorillonite with 400mL deionized water, stir well, adjust the pH of the dispersion to 5, add 12g dimethylaminoethyl methacrylate and 9g dodecyltrimethylammonium bromide, heat to 70℃ and react for 1h, cool to room temperature, filter under reduced pressure to obtain solid, dry at 105℃ for 4h, grind to obtain pretreated montmorillonite.

[0040] Q2. Mix 90g tetrabutyl titanate and 300mL 50wt% ethanol aqueous solution, stir evenly, add 120g of pretreated montmorillonite obtained in step Q1, heat to 70℃ and stir for 3h, cool to room temperature, wash twice with deionized water, and dry at 105℃ for 10h to obtain titanium dioxide / montmorillonite composite material.

[0041] Q3. Mix 5000g of coconut shell activated carbon with 40L of deionized water and stir evenly. Add 160g of 3-vinyl-1-(2-propen-1-yl)-1H-imidazolium tetrafluoroborate and 5000mL of N,N-dimethylformamide. Heat to 60℃ and stir for 24h. Then add 10g of titanium dioxide / montmorillonite composite material and 1.5g of azobisisobutyronitrile obtained in step Q2. React at 80℃ for 3h under nitrogen protection. Cool to room temperature, wash twice with deionized water, filter under reduced pressure to obtain solid, dry at 105℃ for 12h, and grind to obtain modified activated carbon A.

[0042] Preparation Example 2

[0043] The preparation method of modified activated carbon B is the same as that of preparation example 1, except that the amount of dimethylaminoethyl methacrylate added in step Q1 is 8g.

[0044] Preparation Example 3

[0045] The preparation method of modified activated carbon C is the same as that of preparation example 1, except that the amount of dodecyltrimethylammonium bromide added in step Q1 is 5g.

[0046] Preparation Example 4

[0047] The preparation method of modified activated carbon D is the same as that of preparation example 1, except that the amount of tetrabutyl titanate added in step Q2 is 55g.

[0048] Preparation Example 5

[0049] The preparation method of modified activated carbon E is the same as that of preparation example 1, except that the amount of 3-vinyl-1-(2-propen-1-yl)-1H-imidazolium tetrafluoroborate added in step Q3 is 130g.

[0050] Example 1

[0051] A method for removing SO2 and NO X The composite desulfurizing agent of HCl, by weight, includes 30 parts of desulfurizing agent, 40 parts of denitrifying agent, and 12.5 parts of modified activated carbon A; wherein the desulfurizing agent is composed of calcium hydroxide, calcium carbonate and calcium sulfate in a mass ratio of 10:10:0.14, and the denitrifying agent is urea.

[0052] The preparation method of the composite desulfurizing agent of the present invention includes the following steps:

[0053] A composite desulfurizing agent is obtained by mixing a desulfurizing agent, a denitrifying agent, and modified activated carbon A.

[0054] Example 2

[0055] A method for removing SO2 and NO X The composite desulfurizing agent of HCl, by weight, includes 30 parts desulfurizing agent, 40 parts denitrifying agent, 2.5 parts modified activated carbon A1, and 5 parts magnesium oxide; wherein, the desulfurizing agent is composed of calcium hydroxide, calcium carbonate and calcium sulfate in a mass ratio of 10:10:0.14, and the denitrifying agent is urea.

[0056] The preparation method of the composite desulfurizing agent of the present invention includes the following steps:

[0057] A composite desulfurizing agent is obtained by mixing desulfurizing agent, denitrifying agent, modified activated carbon A, and magnesium oxide.

[0058] Example 3

[0059] A method for removing SO2 and NO X The composite desulfurizing agent of HCl, by weight, includes 25 parts desulfurizing agent, 30 parts denitrifying agent, and 10 parts modified activated carbon A; wherein the desulfurizing agent is composed of calcium hydroxide, calcium carbonate and calcium sulfate in a mass ratio of 10:9.5:0.08, and the denitrifying agent is urea.

[0060] The preparation method of the composite desulfurizer of the present invention is the same as that in Example 1.

[0061] Example 4

[0062] A method for removing SO2 and NO X The composite desulfurizing agent of HCl, by weight, includes 35 parts of desulfurizing agent, 50 parts of denitrifying agent, and 15 parts of modified activated carbon A; wherein the desulfurizing agent is composed of calcium hydroxide, calcium carbonate and calcium sulfate in a mass ratio of 10:10.5:0.2, and the denitrifying agent is urea.

[0063] The preparation method of the composite desulfurizer of the present invention is the same as that in Example 1.

[0064] Example 5

[0065] A method for removing SO2 and NO X The composite desulfurizing agent of HCl and its preparation method are the same as in Example 1, except that an equal amount of modified activated carbon B is used to replace modified activated carbon A.

[0066] Example 6

[0067] A method for removing SO2 and NO X The composite desulfurizing agent of HCl and its preparation method are the same as in Example 1, except that an equal amount of modified activated carbon C is used to replace modified activated carbon A.

[0068] Example 7

[0069] A method for removing SO2 and NO X The composite desulfurizing agent of HCl and its preparation method are the same as in Example 1, except that an equal amount of modified activated carbon D is used to replace modified activated carbon A.

[0070] Example 8

[0071] A method for removing SO2 and NO X The composite desulfurizing agent of HCl and its preparation method are described in the same way as in Example 1, except that an equal amount of modified activated carbon E is used to replace modified activated carbon A.

[0072] Example 9

[0073] A method for removing SO2 and NO X The composite desulfurizing agent of HCl and its preparation method are described in the same way as in Example 1, except that the desulfurizing agent is composed of calcium hydroxide and calcium carbonate in a mass ratio of 1:1.

[0074] Comparative Example 1

[0075] A method for removing SO2 and NO X The composite desulfurizing agent and HCl and its preparation method are described in the same way as in Example 1, except that an equal amount of coconut shell activated carbon is used to replace modified activated carbon A.

[0076] Effect evaluation:

[0077] The composite desulfurizing agents prepared in Examples 1-9 and Comparative Example 1 were tested and analyzed. The specific results are shown in Tables 1-2.

[0078] Performance testing:

[0079] (1) A flue gas purification ultra-low emission system was constructed after a small mechanical grate type waste incinerator in a county-level waste incineration plant in southwestern my country. A composite desulfurizing agent was introduced into the high-temperature removal reaction chamber of the flue gas purification ultra-low emission system. The residence time of the high-temperature flue gas in the reaction chamber was 4 seconds, and the dosage of the composite desulfurizing agent was controlled at 15 kg / t of waste. The high-temperature flue gas treatment capacity of this device was 16000 Nm³. 3 / h, SO2 and NO were measured and analyzed before and after treatment using a flue gas analyzer. X and the HCl removal rate.

[0080] Table 1

[0081] Serial Number <![CDATA[SO2 removal rate / %]]> <![CDATA[NO X Removal rate / % HCl removal rate / % Example 1 99.4 98.6 95.2 Example 2 99.6 98.8 95.5 Example 3 98.9 97.5 94.9 Example 4 99.4 98.5 95.2 Example 5 96.5 95.5 94.2 Example 6 97.9 96.4 93.7 Example 7 97.1 95.9 93.3 Example 8 97.4 96.1 94.0 Example 9 99.0 96.5 94.9 Comparative Example 1 93.2 92.4 89.8

[0082] As shown in Table 1, the composite desulfurizing agents prepared in Examples 1-4 have excellent adsorption and removal rates, and can simultaneously and efficiently remove SO2 and NO. X and HCl.

[0083] Compared to Example 1, Examples 5-6 altered the mass ratio of sodium-based montmorillonite, dimethylaminoethyl methacrylate, and dodecyltrimethylammonium bromide in the preparation of modified activated carbon, resulting in a decrease in adsorption capacity. Example 7 changed the mass ratio of pretreated montmorillonite to tetrabutyl titanate, leading to a decrease in the stability and adsorption capacity of the modified activated carbon. Example 8 changed the mass ratio of 3-vinyl-1-(2-propen-1-yl)-1H-imidazolium tetrafluoroborate, coconut shell activated carbon, and titanium dioxide / montmorillonite composite material, resulting in weak grafting stability of the titanium dioxide / montmorillonite composite material and coconut shell activated carbon. All of these changes affected the adsorption capacity of SO2 and NO in Examples 5-8. X The removal efficiency of HCl.

[0084] Compared to Example 1, which did not include calcium sulfate, Example 9 showed a decrease in product strength, affecting removal efficiency, particularly denitrification efficiency.

[0085] Comparative Example 1, compared to Example 1, used an equal amount of commercially available coconut shell activated carbon, SO2, NO X The removal efficiency of HCl decreased significantly.

[0086] (2) The regeneration performance of the composite desulfurizing agents of Examples 1-2 and Comparative Example 1 was evaluated. The composite desulfurizing agents were applied to the flue gas, and the regeneration cycle was 3 times. The SO2 concentration in the flue gas was 500 mg / Nm³. 3 .

[0087] Table 2

[0088]

[0089] As shown in Table 2, the composite desulfurizers prepared in Examples 1-2 have excellent renewability and still have a high desulfurization rate; while the coconut shell activated carbon in Comparative Example 1 has relatively poor adsorption and desulfurization performance after regeneration and recycling.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present application in any way. Although the present application discloses the preferred embodiment as described above, it is not intended to limit the present application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. A method for removing SO2 and NO X A composite desulfurizing agent containing HCl, characterized in that, By weight, the composite desulfurizing agent comprises the following components: 25-35 parts desulfurizing agent, 30-50 parts denitrifying agent, and 10-15 parts modified activated carbon. The desulfurizing agent is a combination of calcium hydroxide, calcium carbonate and calcium sulfate; The method for preparing the modified activated carbon includes the following steps: Q1. Mix sodium-based montmorillonite with deionized water, stir, adjust the pH of the dispersion to 4.5-5.5, add dimethylaminoethyl methacrylate and dodecyltrimethylammonium bromide, heat to 60-80℃ and react for 1-1.5h, cool, filter under reduced pressure to obtain solid, dry, grind, and obtain pretreated montmorillonite; Q2. Mix tetrabutyl titanate and aqueous ethanol solution, stir, add the pretreated montmorillonite obtained in step Q1, heat to 60-80℃ and stir to react for 2-4 hours, cool, wash and dry to obtain titanium dioxide / montmorillonite composite material. Q3. Mix coconut shell activated carbon with deionized water, stir, add 3-vinyl-1-(2-propen-1-yl)-1H-imidazolium tetrafluoroborate and N,N-dimethylformamide, heat to 50-70℃ and stir for 20-30h, then add the titanium dioxide / montmorillonite composite material obtained in step Q2 and the initiator, and react at 60-80℃ under inert gas protection, cool, wash, filter and dry to obtain modified activated carbon; The mass ratio of sodium montmorillonite, dimethylaminoethyl methacrylate, and dodecyltrimethylammonium bromide in step Q1 is 10:(0.5-0.7):(0.35-0.55). The mass ratio of the pretreated montmorillonite to tetrabutyl titanate in step Q2 is 1:(0.5-1). The mass ratio of 3-vinyl-1-(2-propen-1-yl)-1H-imidazolium tetrafluoroborate, coconut shell activated carbon, and titanium dioxide / montmorillonite composite material in step Q3 is (14-18):(400-600):

1.

2. A method for removing SO2 and NO according to claim 1 X A composite desulfurizing agent containing HCl, characterized in that, The mass ratio of calcium hydroxide, calcium carbonate, and calcium sulfate is 10:(9.5-10.5):(0.08-0.2).

3. A method for removing SO2 and NO according to claim 1 X A composite desulfurizing agent containing HCl, characterized in that, The denitrifying agent comprises any one or more of urea, polyaniline, and polyamide.

4. A method for removing SO2 and NO according to claim 1 X A composite desulfurizing agent containing HCl, characterized in that, The components also include 4-6 parts by weight of magnesium oxide.

5. A method for removing SO2 and NO according to any one of claims 1-4 X The method for preparing a composite desulfurizing agent of HCl is characterized in that, The process includes the following steps: mixing desulfurizing agent, denitrifying agent, and modified activated carbon to obtain a composite desulfurizing agent.

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