Preparation method of gemini benzene sulfonate intercalated hydrotalcite and application of gemini benzene sulfonate intercalated hydrotalcite in flue gas desulfurization

Abstract

The invention discloses a composite metal oxide desulfurizer as well as a preparation method and application thereof, and the preparation method comprises the following steps: dissolving a metal active component precursor salt and a precipitator in a solvent to obtain a mixed solution A; dissolving gemini benzene sulfonate in a solvent to obtain a mixed solution B; the mixed solution A and the mixed solution B are mixed and then placed in a closed environment without a carbon dioxide atmosphere, a hydrothermal reaction is conducted, and hydrotalcite compound crystals are obtained; roasting the hydrotalcite compound crystal to obtain powder; mixing the powder, a binder and a pore-enlarging agent, and performing extrusion forming to obtain the desulfurizing agent, the molar ratio of the metal ions to the precipitant to the gemini benzene sulfonate in the metal active component precursor salt is 1: (0.8-1.2): (0.1-0.4). No organic solvent is added, so that the method is simple and green; the prepared hydrotalcite compound is high in crystal crystallinity, and the desulfurization activity is enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical environmental protection, and particularly relates to a preparation method of a gemini benzenesulfonate intercalated hydrotalcite and its application in flue gas desulfurization. Background Art

[0002] SO2 is a colorless and strongly pungent acidic gas, and its large-scale emission will cause serious harm to humans and the ecological environment. As a common air pollutant, SO2 mainly comes from the flue gas generated by the combustion of fossil energy. In order to reduce the emission of SO2, various flue gas treatment technologies have been proposed, which can be classified into wet, dry, and semi-dry flue gas desulfurization according to the process characteristics.

[0003] The wet flue gas desulfurization technology is mature and widely used, but its system is complex, the equipment is huge, the investment and operation costs are high, and there is secondary pollution. Compared with the wet flue gas desulfurization technology, the dry desulfurization has the advantages of small floor area, simple equipment operation, and low cost, and has been widely concerned since it was proposed.

[0004] Dry flue gas desulfurization refers to the catalytic conversion of SO in the flue gas into metal sulfate or sulfite under the action of a desulfurizer and fixing it, so as to effectively reduce the concentration of sulfur oxides in the discharged flue gas. The desulfurizer can generally be divided into two types: renewable and non-renewable. Among them, the renewable desulfurizer refers to the catalytic conversion of sulfur in metal sulfate or sulfite into SO2, H2S or elemental sulfur under the action of a reducing gas, so as to restore the initial reaction activity of the desulfurizer. x

[0005] ​The selectable renewable desulfurizers mainly include single metal oxides, supported adsorbents, spinels, and composite metal oxides derived from hydrotalcite-like compounds. Metal-based catalysts include transition metals, noble metals, and non-noble metals, which have good structural tunability, abundant Lewis acid active sites, and high activity stability, thus showing excellent catalytic reduction reaction activity. However, such adsorbents are difficult to reduce and have a low sulfur capacity. Supported adsorbents mainly use some materials with high surface area, high porosity, and good chemical stability as carriers, such as γ-Al2O3, activated carbon, and molecular sieves, and load some metal active components. They have the advantage of low adsorption temperature (25-50°C), but such adsorbents have a low sulfur capacity and are easily affected by factors such as temperature and adsorption gas composition. Spinel-type desulfurizers have a simple preparation process, good desulfurization effect, and mature process, and are the main type of desulfurization adsorbents for commercial applications at present. However, the Mg content in such desulfurizers is low, and the bulk phase sulfates are difficult to regenerate and reduce, resulting in unstable activity. The composite metal oxide desulfurizer has a relatively high Mg content and has become a research hotspot due to its advantages such as high sulfur capacity, large specific surface area, and good cycle stability. The desulfurization performance of the composite metal oxide desulfurizer is closely related to the structure and morphology of the uncalcined hydrotalcite-like compound (LDHs) crystals. LDHs belong to the hexagonal crystal system, and the two-dimensional lamellar plates are arranged layer by layer in the three-dimensional direction. Some M 2+ in the lamellar plates can be isomorphously substituted by M 3+ , making it positively charged. The guest anions are inserted between the lamellar plates to neutralize the positive charge of the main lamellar plates, making the overall crystal structure electrically neutral. The intercalated anions can affect the layer spacing of the LDHs crystals along the c-axis direction, which is mainly related to the size, quantity, valence state of the anions, and the interaction strength with the hydroxyl groups of the main lamellar plates. Then, how to adjust the structural properties of the hydrotalcite-like compounds to further improve the desulfurization performance of the composite metal oxide desulfurizer obtained by calcination diffraction. Summary of the Invention

[0006] The problem to be solved by the present invention is: how to further improve the desulfurization performance of the composite metal oxide desulfurizer.

[0007] The purpose of the present invention is to provide a method for preparing a composite metal oxide desulfurizer using gemini benzenesulfonate, including:

[0008] Dissolve the metal active component precursor salt and the precipitant in a solvent to obtain a mixed solution A;

[0009] Dissolve the gemini benzenesulfonate in a solvent to obtain a mixed solution B;

[0010] Mix the mixed solution A and the mixed solution B and carry out a hydrothermal reaction in an atmosphere without carbon dioxide and in a sealed environment to obtain hydrotalcite-like compound crystals. The temperature of the hydrothermal reaction is 120-180°C, and the time of the hydrothermal reaction is 4-10 h;

[0011] The hydrotalcite-like compound crystals are calcined to obtain a powder. The calcination temperature is 450-550 °C and the calcination time is 5-12 h;

[0012] The powder, binder and pore-expanding agent are mixed and extruded into shape to obtain the desulfurizer;

[0013] The molar ratio of metal ions, precipitating agent and gemini benzenesulfonate in the metal active component precursor salt is: 1:2-10:0.1-0.4.

[0014] As a possible design, the molecular structural formula of the gemini benzenesulfonate is as follows:

[0015]

[0016] Among them, R1 is an alkyl group of C 10 -C 16 and R2 is an alkylene group of C2-C6.

[0017] As a possible design, the metal active components in the metal active component precursor salt include Mg 2+ , Al 3+ and Ce 3+ , and the molar ratio is Mg 2+ : Al 3+ : Ce 3+ =2:0.5-1:0-0.5.

[0018] As a possible design, the molar concentration ratio of the precipitating agent in the mixed solution A to the total molar concentration of metal ions in the metal active component is 2-10:1.

[0019] As a possible design, the mass ratio of the binder to the powder is 1:1-1:3, and the content of the pore-expanding agent in the desulfurizer is 1-5 wt%.

[0020] As a possible design, the metal active component precursor salt includes at least one of sulfates, chlorides, nitrates and acetates of the metal active component.

[0021] As a possible design, the precipitating agent is urea.

[0022] As a possible design, the binder is aluminum glue and the pore-expanding agent is sesbania powder.

[0023] As a possible design, the hydrotalcite-like compound crystals are dried before being calcined. The drying temperature is 60-90 °C. A washing step may also be included before drying, and grinding may also be included between drying and calcination. The particle size of the powder obtained after grinding is generally not more than 300 mesh.

[0024] The carbon dioxide-free atmosphere can be a nitrogen atmosphere or an inert gas atmosphere. Before the reaction under high pressure, the mixture A and the mixture B can also be stirred evenly at room temperature first, and the stirring time is generally about 0.5 h. The reaction process can be carried out in common high-pressure equipment, such as a high-pressure reaction kettle, etc.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1. In the process of preparing the hydrotalcite-like compound crystal, the gemini benzenesulfonate is added in the present invention, and the gemini benzenesulfonate ions intercalate into the hydrotalcite layer interlayer, thereby affecting the morphology of the final hydrotalcite-like compound crystal and the performance of the desulfurizer.

[0027] 2. By adjusting the length of the hydrophobic end alkyl chain in the gemini benzenesulfonate ions, the interlayer spacing and the layer thickness of the hydrotalcite can be effectively adjusted, thereby effectively changing the morphology of the hydrotalcite-like compound crystal and finally affecting the performance of the composite metal oxide desulfurizer obtained after sintering.

[0028] 3. The method for preparing the composite metal oxide desulfurizer by using the gemini benzenesulfonate disclosed in the present invention is obtained by a one-step method without adding any organic solvents, which is simple and green; the desulfurization activity of the prepared composite metal oxide desulfurizer is improved.

[0029] 4. Through the preparation method disclosed in the present invention, the prepared composite metal oxide desulfurizer is very suitable for desulfurization in gases, especially for flue gas desulfurization. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Figure 1 It is the structural formula diagram of the gemini benzenesulfonate ions in Example 1;

[0032] Figure 2 It is the structural formula diagram of the gemini benzenesulfonate ions in Example 2;

[0033] Figure 3 It is the SEM diagram of the composite metal oxide in Example 1;

[0034] Figure 4 It is the SEM diagram of the composite metal oxide in Comparative Example 1. Detailed Embodiments

[0035] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clear and understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0036] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0037] It should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0038] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality" means two or more unless otherwise specifically defined.

[0039] Example 1

[0040] This example provides a preparation method of a composite metal oxide desulfurizer, and its specific steps include:

[0041] (1) Preparation of hydrotalcite-like compounds

[0042] Prepare 500 ml of a mixed solution of magnesium nitrate, aluminum nitrate, cerium nitrate and urea, denoted as mixed solution A. Among them: the concentration of magnesium nitrate is 0.65 mol / L, the concentration of aluminum nitrate is 0.31 mol / L, the concentration of cerium nitrate is 0.04 mol / L, and the concentration of urea is 5 mol / L.

[0043] Prepare 250 ml of a mixed solution of gemini benzenesulfonate anionic surfactant, denoted as mixed solution B, among which: the structural formula of the gemini benzenesulfonate ion in gemini benzenesulfonate is as Figure 1 , and the concentration is 0.15 mol / L.

[0044] After mixing and stirring the mixed solutions A and B at room temperature for 0.5 h, transfer them to a 1000 ml polytetrafluoroethylene high-pressure reactor and react at 120 °C for 6 h under a nitrogen atmosphere. Then, perform centrifugal separation, wash with deionized water until neutral, and finally wash once with ethanol. The obtained solid is dried overnight in an oven at 90 °C and then ground into a powder (greater than 300 mesh).

[0045] (2) Preparation of the composite metal oxide desulfurizer

[0046] Transfer the hydrotalcite-like compound powder prepared in step (1) to a muffle furnace and calcine it at 500 °C for 6 h in an air atmosphere to obtain the corresponding composite metal oxide powder, where the heating rate is 2 °C / min.

[0047] Weigh 70 g of the composite metal oxide powder, add 40 g of aluminum gel, 2.2 g of talc powder, and 60 g of deionized water. After mixing well, extrude into a shape, and then place it at room temperature for 48 h, dry at 100 °C for 12 h, and calcine at 500 °C for 4 h to obtain the corresponding desulfurizer S1.

[0048] Example 2

[0049] This example provides a method for preparing a composite metal oxide desulfurizer, and its specific steps include:

[0050] (1) Preparation of the hydrotalcite-like compound

[0051] Prepare a 500 ml mixed solution of magnesium nitrate, aluminum nitrate, cerium nitrate, and urea, denoted as mixed solution A. Among them, the concentration of magnesium nitrate is 0.65 mol / L, the concentration of aluminum nitrate is 0.31 mol / L, the concentration of cerium nitrate is 0.04 mol / L, and the concentration of urea is 5 mol / L.

[0052] Prepare a 250 ml mixed solution of gemini benzenesulfonate anionic surfactant, denoted as mixed solution B, where the structural formula of the gemini benzenesulfonate ion in gemini benzenesulfonate is as Figure 2 , and the concentration is 0.15 mol / L.

[0053] After mixing and stirring the mixed solutions A and B at room temperature for 0.5 h, transfer them to a 1000 ml polytetrafluoroethylene high-pressure reactor, and react at 120 °C for 6 h under a nitrogen atmosphere. Then, perform centrifugal separation, wash with deionized water until neutral, and finally wash once with ethanol. The obtained solid is dried overnight in an oven at 90 °C and then ground into a powder (greater than 300 mesh).

[0054] (2) Preparation of the composite metal oxide desulfurizer

[0055] Transfer the hydrotalcite - like compound powder prepared in step (1) to a muffle furnace, and calcine it at 500 °C for 6 h in an air atmosphere to obtain the corresponding composite metal oxide powder, where the heating rate is 2 °C / min.

[0056] Weigh 70 g of the composite metal oxide powder, add 40 g of aluminum gel, 2.2 g of sesbania powder and 60 g of deionized water. After mixing evenly, extrude it into a shape, and then place it at room temperature for 48 h, dry it at 100 °C for 12 h, and calcine it at 500 °C for 4 h to obtain the corresponding desulfurizer S2.

[0057] Example 3

[0058] This example provides a preparation method of a composite metal oxide desulfurizer, and its specific steps include:

[0059] (1) Preparation of hydrotalcite - like compound

[0060] Prepare a 500 - ml mixed solution of magnesium nitrate, aluminum nitrate, cerium nitrate and urea, denoted as mixed solution A. Among them, the concentration of magnesium nitrate is 0.65 mol / L, the concentration of aluminum nitrate is 0.31 mol / L, the concentration of cerium nitrate is 0.04 mol / L, and the concentration of urea is 5 mol / L.

[0061] Prepare a 250 - ml mixed solution of gemini benzenesulfonate anionic surfactant, denoted as mixed solution B. Among them, the structural formula of the gemini benzenesulfonate anion in gemini benzenesulfonate is as Figure 1 , and the concentration is 0.3 mol / L.

[0062] Mix and stir the mixed solutions A and B at room temperature for 0.5 h, then transfer them to a 1000 - ml polytetrafluoroethylene high - pressure reactor, and react at 120 °C for 6 h in a nitrogen atmosphere. Then, perform centrifugal separation, wash with deionized water until neutral, and finally wash once with ethanol. The obtained solid is dried overnight in an oven at 90 °C and then ground into powder (greater than 300 mesh).

[0063] (2) Preparation of composite metal oxide desulfurizer

[0064] Transfer the hydrotalcite - like compound powder prepared in step (1) to a muffle furnace, and calcine it at 500 °C for 6 h in an air atmosphere to obtain the corresponding composite metal oxide powder, where the heating rate is 2 °C / min.

[0065] Weigh 70 g of the composite metal oxide powder, add 40 g of aluminum gel, 2.2 g of sesbania powder and 60 g of deionized water. After mixing evenly, extrude it into a shape, and then place it at room temperature for 48 h, dry it at 100 °C for 12 h, and calcine it at 500 °C for 4 h to obtain the corresponding desulfurizer S3.

[0066] Comparative Example 1

[0067] This embodiment provides a method for preparing a composite metal oxide desulfurizer, and the specific steps include:

[0068] (1) Preparation of hydrotalcite-like compounds

[0069] Prepare 500 ml of a mixed solution of magnesium nitrate, aluminum nitrate, cerium nitrate and urea, denoted as mixed solution A. Among them, the concentration of magnesium nitrate is 0.65 mol / L, the concentration of aluminum nitrate is 0.31 mol / L, the concentration of cerium nitrate is 0.04 mol / L, and the concentration of urea is 5 mol / L.

[0070] Transfer mixed solution A and 250 ml of deionized water to a 1000 ml polytetrafluoroethylene high-pressure reaction kettle. The polytetrafluoroethylene high-pressure reaction kettle reacts at 120 °C for 6 h. Then, perform centrifugal separation, wash with deionized water until neutral, and finally wash once with ethanol. The obtained solid is dried overnight in an oven at 90 °C and then ground into powder (greater than 300 mesh).

[0071] (2) Preparation of composite metal oxide desulfurizer

[0072] Transfer the hydrotalcite-like compound powder prepared in step (1) to a muffle furnace and calcine it at 500 °C for 6 h in an air atmosphere to obtain the corresponding composite metal oxide powder, where the heating rate is 2 °C / min.

[0073] Weigh 70 g of the composite metal oxide powder, add 40 g of aluminum gel, 2.2 g of sesbania powder and 60 g of deionized water, mix well and then extrude into shape. Then, place it at room temperature for 48 h, dry at 100 °C for 12 h, and calcine at 500 °C for 4 h to obtain the corresponding desulfurizer D1.

[0074] Perform activity evaluation on the desulfurizers obtained in Examples 1-3 and Comparative Example 1, as follows.

[0075] The flue gas composition for the evaluation experiment can be: the volume fraction of SO2 is 0.1-2%, the volume fraction of O2 is 2-4%, the volume fraction of CO2 is 10-30%, and the rest is nitrogen. The regeneration of the desulfurizer in the evaluation experiment uses H2 / N2, and the volume fraction of H2 is about 10%.

[0076] The composition of the inlet raw material gas in this experiment is shown in Table 1, and the space velocity of the desulfurization reaction is 500 h -1 , and the desulfurization activity evaluation is carried out at a reaction temperature of 500 °C.

[0077] Table 1 Composition of raw material gas

[0078] Gas composition <![CDATA[SO2]]> <![CDATA[O2]]> <![CDATA[CO2]]> <![CDATA[N2]]> Volume percentage (%) 0.5 4 20 75.5

[0079] The evaluation test began. First, 3 g of small particles (composite metal oxide desulfurizer) with a particle size of 20 - 40 mesh were weighed and loaded into a fixed-bed micro-reactor, and were fixed with quartz wool on the upper and lower layers respectively.

[0080] During the reaction process, when the SO2 content in the outlet gas was higher than 400 mg / m 3 3, the gas flow was switched to a reducing gas flow. After the regeneration was completed, the next desulfurization reaction cycle was entered, and the sulfur capacity of the composite metal oxide desulfurizer at this time was calculated.

[0081] Table 2 Desulfurization effect of the composite metal oxide desulfurizer prepared by the present invention

[0082]

[0083]

[0084] As can be seen from Table 2, by adding gemini benzenesulfonate during the preparation process of the hydrotalcite-like compound, it is beneficial to improve the sulfur capacity of the desulfurizer, thereby improving the desulfurization effect of the composite metal oxide desulfurizer. The regeneration of this composite metal oxide desulfurizer can be achieved only with hydrogen. The regenerated composite metal oxide desulfurizer still has a high sulfur capacity.

[0085] As can be seen from Examples 1 - 3, during the preparation process of the composite metal oxide desulfurizer, it is only necessary to dissolve the gemini benzenesulfonate in water and then react it with the metal ion solution. This process does not require the addition of any organic solvents, the reaction conditions are mild, the preparation steps are simple, and the desulfurization activity of the prepared composite metal oxide desulfurizer is improved. Therefore, it is worthy of popularization and application.

[0086] It was found that during the preparation process of the hydrotalcite-like compound crystals, when gemini benzenesulfonate was added, the gemini benzenesulfonate ions intercalated into the hydrotalcite layer, thus affecting the morphology of the final hydrotalcite-like compound crystals and the performance of the desulfurizer. It was also found that by adjusting the length of the hydrophobic alkyl chain in the gemini benzenesulfonate ions, the interlayer spacing and layer thickness of the hydrotalcite can be effectively adjusted, thereby effectively changing the morphology of the hydrotalcite-like compound crystals, and finally affecting the performance of the composite metal oxide desulfurizer obtained after sintering.

[0087] The above specific embodiments further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a composite metal oxide desulfurizer using bisphenylsulfonate, characterized in that: The method includes: Dissolving a metal active component precursor salt and a precipitant in a solvent to obtain a mixed solution A; Dissolving a gemini benzenesulfonate in a solvent to obtain a mixed solution B; Mixing the mixed solution A and the mixed solution B and subjecting them to hydrothermal reaction in an environment without carbon dioxide atmosphere and in a sealed environment to obtain a hydrotalcite-like compound crystal. The temperature of the hydrothermal reaction is 120-180°C, and the time of the hydrothermal reaction is 4-10 h; Performing calcination treatment on the hydrotalcite-like compound crystal to obtain a powder. The calcination temperature is 450-550°C, and the calcination time is 5-12 h; Mixing the powder, a binder, and a pore-expanding agent, and extruding them into a mold to obtain the desulfurizer; The molar ratio of the metal ion in the metal active component precursor salt, the precipitant, and the gemini benzenesulfonate is: 1:2-10:0.1-0.

4.

2. The method for preparing a desulfurizer of composite metal oxide desulfurizer using gemini benzene sulfonate according to claim 1, characterized in that: The molecular structural formula of the gemini benzenesulfonate is as follows: Among them, R1 is an alkyl group of C 10 -C 16 , and R2 is an alkylene group of C2-C6.

3. The method for preparing a desulfurizer of composite metal oxide desulfurizer using gemini benzene sulfonate according to claim 1, characterized in that: The metal active component in the metal active component precursor salt includes Mg 2+ , Al 3+ and Ce 3+ , and the molar ratio is Mg 2+ : Al 3+ : Ce 3+ = 2:0.5 to 1:0 to 0.

5.

4. The method for preparing a desulfurizer of composite metal oxide desulfurizer using gemini benzene sulfonate according to claim 1, characterized in that: The precipitant in the mixed solution A is urea, and the total molar concentration ratio of it to the metal ion in the metal active component is 2-10:

1.

5. The method for preparing a desulfurizer of composite metal oxide desulfurizer using gemini benzene sulfonate according to claim 1, characterized in that: The mass ratio of the binder to the powder is 1:1-1:3, and the content of the pore-expanding agent in the desulfurizer is 1-5 wt%.

6. The method for preparing a desulfurizer of composite metal oxide desulfurizer using gemini benzene sulfonate according to claim 1 or 5, characterized in that: The binder is aluminum glue, and the pore-expanding agent is sesbania powder.

7. The method for preparing a desulfurizer of composite metal oxide desulfurizer using gemini benzene sulfonate according to claim 1, characterized in that: The metal active component precursor salt includes at least one of sulfates, chlorides, nitrates, and acetates of the metal active component.

8. The method for preparing a desulfurizer of composite metal oxide using gemini benzene sulfonate as claimed in claim 1, wherein: Before the hydrotalcite-like compound crystal is subjected to calcination treatment, it is dried. The drying temperature is 60-90°C.

9. The composite metal oxide desulfurizer obtained by the method according to any one of claims 1-8.

10. The application of the composite metal oxide desulfurizer according to claim 9 in flue gas desulfurization.

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