Flue gas desulfurization adsorbent capable of recycling sulfur and carbon as well as preparation method and application of flue gas desulfurization adsorbent

Abstract

The invention provides a flue gas desulfurization adsorbent capable of recovering sulfur and carbon, a preparation method of the flue gas desulfurization adsorbent, and application of the adsorbent in flue gas desulfurization. The material is prepared by the following method: after polyamine is fully methylated, calcium oxide powder is added to fully impregnate a propyl alcohol solution of the polyamine, and drying is performed. Then adding a lignosulfonate aqueous solution into the mixture, completing the digestion process of calcium oxide along with stirring, and then filtering and roasting to obtain the flue gas desulfurization adsorbent particles capable of recovering sulfur and carbon. The adsorbent obtained by the invention can complete desorption on SO2 and CO2 in sequence at high temperature, the desorption process of SO2 and the desorption process of CO2 do not influence each other, and the recycling of sulfur and carbon resources by the adsorbent is realized. In addition, the preparation method provided by the invention is simple, efficient, economical and feasible, the requirements of used equipment and instruments are simple, the yield is high, and the investment and operation cost can be effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of flue gas sulfur and carbon recovery, and in particular relates to a flue gas desulfurization adsorbent capable of recovering sulfur and carbon, and a preparation method and application thereof. Background Art

[0002] Since the slurry contains high concentrations of chloride ions, sulfate ions, and sulfite ions, it has a strong corrosive effect on metals. A typical 300MW coal-fired power generation unit burns 2 million tons of coal per year. Assuming the sulfur content in the coal is 1%, the power plant can produce more than 100,000 tons of desulfurized gypsum per year. Although desulfurized gypsum can be reused as building materials, its utilization rate is only 50%-60% due to its low added value, which means that a considerable amount of desulfurized gypsum can only be disposed of as solid waste in landfills.

[0003] Recovering SO2 from flue gas can convert it into useful chemical products, such as sulfuric acid, sulfur or other sulfur-containing compounds, which are widely used in fertilizer production, pharmaceuticals, papermaking, textiles and other industries. SO2 resource utilization not only reduces the cost of waste treatment, but also creates additional economic value. For companies that rely on external procurement of sulfur-containing raw materials, recycling and utilizing their own SO2 emissions can reduce the procurement cost of raw materials and significantly improve corporate competitiveness.

[0004] Developing adsorbents to achieve adsorption and desorption separation of SO2 in flue gas can effectively avoid secondary pollution and realize multiple chemical adsorption of SO2 and desorption and collection of SO2 cycles, which is of great significance to the development of flue gas desulfurization technology. At present, the most studied adsorbents are ionic liquid adsorbents, which have good stability, high sulfur dioxide capacity and low volatility. By adjusting the operating conditions such as the temperature and pressure of the interaction between ionic liquid adsorbents and SO2, the reversible adsorption of SO2 can be achieved, making the recycling of SO2 possible. However, the synthesis process of most ionic liquid adsorbents is relatively complicated, requiring a large amount of high-purity organic solvents, and the cost is particularly expensive. Secondly, ionic liquids generally exist in liquid phase and show high viscosity, which leads to increased mass transfer resistance and excessive energy consumption in large-scale industrial applications. In particular, it causes a significant decrease in efficiency in the second half of the SO2 adsorption and SO2 desorption process. In addition, in the actual flue gas environment, components such as CO2 and NOx in addition to SO2 will compete with SO2 for the adsorption sites of ionic liquids, reducing the selectivity and capture efficiency of ionic liquids for SO2. Therefore, the above disadvantages limit the practical application of ionic liquid adsorbents in industry.

[0005] Patent CN119215635A discloses a desulfurizer for removing sulfur-containing gas from flue gas and its preparation method, wherein the main absorption component is calcium magnesium carbonate, calcium fluorophosphate or manganese oxide, the amino acid auxiliary agent is β-alanine or L-alanine, the inhibitor is sodium bicarbonate, and the antioxidant is polyol or polyphenol. Because the mass content of sodium bicarbonate in the preparation method is significantly higher than the mass content of the main absorption component, and the solubility of calcium magnesium carbonate, calcium fluorophosphate or manganese oxide is relatively low, the desulfurizer is actually a suspension of calcium magnesium carbonate, calcium fluorophosphate or manganese oxide dispersed in a sodium bicarbonate aqueous solution. This technology produces wastewater after desulfurization, which brings secondary pollution to the environment, and the SO2 removed is also difficult to recycle. Patent CN110124449A discloses a composite ammonia absorbent for absorbing sulfur dioxide and its preparation method, but the raw materials required to prepare the absorbent are expensive, the regeneration energy consumption is high, and its desulfurization selectivity needs to be improved when applied to actual factory flue gas containing SO2 and CO2 at the same time.

[0006] Therefore, it is of great significance to provide a method for preparing a flue gas desulfurization adsorbent with low cost and high efficiency in recovering sulfur and carbon. Summary of the invention

[0007] In order to solve the above technical problems, the present invention proposes a flue gas desulfurization adsorbent capable of recovering sulfur and carbon, and a preparation method and application thereof.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A flue gas desulfurization adsorbent capable of recovering sulfur and carbon, the preparation method of which comprises the following steps:

[0010] The polyamine is continuously stirred with formaldehyde and formic acid under a nitrogen atmosphere. After the polyamine is fully methylated, ammonia water is added thereto, and impurities such as formaldehyde, water and ammonia water are removed by rotary evaporation. Propanol is added to the product after rotary evaporation, and the supernatant is taken after centrifugation to obtain a propanol solution of the methylated polyamine. Calcium oxide powder is added to the solution, and stirred and fully mixed to achieve full impregnation of the methylated polyamine with the calcium oxide particles. After the impregnated product is dried, a certain amount of lignin sulfonate aqueous solution is poured therein, and the digestion process of calcium oxide is completed with stirring, and then filtered and roasted to obtain the flue gas desulfurization adsorbent particles that can recover sulfur and carbon.

[0011] Beneficial effects: The primary and secondary amine groups of the polyamine are converted into tertiary amines through a methylation reaction. After the calcium oxide particles are impregnated with a propanol solution thereof, the methylated polyamine molecular layer can be tightly wrapped on the outer surface of the calcium oxide particles. After adding the aqueous solution of lignin sulfonate, calcium oxide and water undergo a digestion reaction to generate calcium hydroxide crystals with a larger molar volume. The "expansion" of the calcium hydroxide crystals can increase the specific surface area of ​​the polyamine molecular layer. Moreover, the addition of lignin sulfonate effectively controls the growth direction of the calcium hydroxide crystals, promotes the directional growth of the calcium hydroxide crystals, further increases the specific surface area of ​​the polyamine molecular layer, and even promotes the calcium hydroxide crystals to "tear" the polyamine molecular layer, increasing the probability of contact and reaction between the active sites of calcium hydroxide and the flue gas. Since the calcium hydroxide crystals can be redissolved, granulated and grown in the polyamine solution, the preparation method of the adsorbent that first digests the calcium oxide and then impregnates the loaded polyamine destroys the original structure of the calcium hydroxide crystals, making it difficult to accurately control the loading of the calcium hydroxide on the polyamine. The present invention first uses calcium oxide as a carrier to load polyamine, and then realizes the granulation and growth of calcium hydroxide crystal particles, which effectively avoids the above phenomenon, and the finally prepared adsorbent has a controllable structure and a large specific surface area. When the adsorbent contacts the flue gas, there are a large number of tertiary amine groups and calcium hydroxide active sites that can chemically adsorb SO2 and CO2 in the flue gas respectively. The tertiary amine contained in the polyamine can directly chemically adsorb SO2, but the chemical adsorption amount of CO2 is very low, so it has a high SO2 selectivity. The residual CO2 is then chemically adsorbed by the calcium hydroxide crystal active sites below the polyamine molecular layer.

[0012] Preferably, the mass ratio of the polyamine to calcium oxide is 0.05 to 10:1.

[0013] Preferably, the polyamine includes at least one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine.

[0014] Beneficial effects: The flue gas desulfurization adsorbent with recoverable sulfur and carbon obtained by the present invention can efficiently adsorb SO2 and CO2 in flue gas by changing the relative mass ratio of polyamine to calcium oxide before the methylation reaction. After a certain amount of calcium oxide particles are impregnated with the polyamine solution after the methylation reaction, the polyamine molecular layer is tightly wrapped on the outer surface of the calcium oxide particles. Different types of polyamines have different viscosities. If the amount of polyamine is too little, the polyamine molecular layer attached to the outer surface of the calcium oxide particles is too thin and cannot continuously wrap the calcium oxide particles. The number of tertiary amine sites loaded on the outer surface of the calcium oxide particles is relatively small, which reduces the chemical adsorption of SO2 in the flue gas by the adsorbent. If the amount of polyamine is too much, the viscosity is too high, and the polyamine molecular layer loaded on the outer surface of the calcium oxide particles is too thick, which hinders the subsequent effective contact between calcium oxide and the lignin sulfonate aqueous solution, inhibits the digestion of calcium oxide and the subsequent directional growth of calcium hydroxide crystals, causing calcium hydroxide crystals to be difficult to "tear" the polyamine molecular layer, reducing the chemical adsorption of CO2 in the flue gas by the adsorbent.

[0015] Preferably, the mass percentage of the lignin sulfonate aqueous solution is 0.02% to 10%, and the mass ratio of lignin sulfonate to calcium oxide is 0.005 to 2:1.

[0016] Preferably, the lignin sulfonate includes at least one of sodium lignin sulfonate, magnesium lignin sulfonate and calcium lignin sulfonate.

[0017] Beneficial effects: The flue gas desulfurization adsorbent with recoverable sulfur and carbon obtained by the present invention can efficiently adsorb SO2 and CO2 in flue gas, which is also achieved by changing the mass concentration of the lignin sulfonate aqueous solution and the relative mass ratio of lignin sulfonate to calcium oxide. The water in the lignin sulfonate aqueous solution directly participates in the digestion reaction of calcium oxide as a reactant. The lignin sulfonate ions can be complexed with the calcium ions in the calcium hydroxide crystals, reducing the concentration of free calcium ions in the aqueous solution that can be used for calcium hydroxide nucleation, controlling the growth direction of the calcium hydroxide crystals, and increasing the specific surface area of ​​the polyamine wrapped on the outer surface of the calcium oxide particles, further achieving the directional "tearing" of the polyamine molecular layer by the calcium hydroxide crystals in the adsorbent, and providing more reaction sites for the adsorbent to adsorb CO2 in flue gas. If the mass percentage of the lignin sulfonate aqueous solution is too high, it will cause the local viscosity in the digestion solution to be too high, which is easy to cause the agglomeration of calcium hydroxide particles. The mass ratio of lignin sulfonate to calcium oxide is too large. The lignin sulfonate anions will complex the excessive calcium ions in the calcium hydroxide crystals, affecting the growth direction of the calcium hydroxide crystals, forming a disordered crystal structure, and reducing the adsorption efficiency of the adsorbent for SO2 and CO2.

[0018] Preferably, during the digestion of calcium oxide by the aqueous solution of lignin sulfonate, the digestion temperature is 30 to 120° C., and the digestion time is 15 minutes to 3 hours.

[0019] Beneficial effects: The digestion temperature directly determines the digestion reaction rate of calcium hydroxide and water and the complexation rate of lignin sulfonate ions and calcium ions, and the digestion time determines the digestion degree of calcium hydroxide. Appropriate digestion temperature can effectively prevent calcium oxide from generating a large amount of heat during the digestion process, causing a sudden increase in the local temperature of the system, and prevent the agglomeration of particles when the calcium hydroxide grains grow; the appropriate digestion time can ensure the full progress of the digestion reaction and the directional growth of calcium hydroxide grains, which is conducive to controlling the growth direction of calcium hydroxide crystals, so that the calcium hydroxide crystals in the adsorbent can directional "tear" the polyamine molecular layer, increase the specific surface area of ​​the adsorbent, and provide more reaction sites for the adsorbent to adsorb CO2 in flue gas.

[0020] Preferably, the roasting temperature of the product after the digestion reaction of lignin sulfonate with calcium oxide is 90 to 350° C., and the roasting time is 30 minutes to 3 hours.

[0021] Beneficial effects: Heat treatment of the digestion product at an appropriate roasting temperature and roasting time can volatilize or decompose the polyamine molecules remaining on the surface of the calcium hydroxide crystals and not firmly supported by the calcium hydroxide crystals, and can also further embed the polyamine molecules firmly supported by the calcium hydroxide crystals into the calcium hydroxide lattice structure, which is beneficial to reduce the binding energy between the calcium hydroxide grains and inhibit the agglomeration of the calcium hydroxide particles.

[0022] A flue gas desulfurization adsorbent capable of recovering sulfur and carbon and a preparation method thereof. The flue gas desulfurization adsorbent capable of recovering sulfur and carbon is prepared.

[0023] Beneficial effects: The adsorbent particles obtained by the present invention have a large number of tertiary amine groups and calcium hydroxide active sites on their surfaces, which can chemically adsorb SO2 and CO2 in the flue gas respectively. The tertiary amine contained in the polyamine can directly chemically adsorb SO2, but the chemical adsorption amount of CO2 is very low, so it has a high selectivity for SO2. The residual CO2 is then chemically adsorbed by the calcium hydroxide crystal active sites below the polyamine molecular layer.

[0024] Application of a flue gas desulfurization adsorbent capable of recovering sulfur and carbon in recovering sulfur and carbon resources in flue gas

[0025] Beneficial effect: After the adsorbent prepared by the present invention adsorbs SO2 and CO2 in the flue gas, due to the large difference in the chemical adsorption energies of the tertiary amine groups in the polyamine and the active sites of calcium hydroxide for SO2 and CO2, the adsorbent can sequentially desorb SO2 and CO2 through a programmed temperature rising process, and the desorption processes of SO2 and CO2 do not affect each other, thereby realizing the recycling of sulfur and carbon resources by the adsorbent.

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] The present invention loads the polyamine after methylation reaction on the outer surface of calcium oxide particles, and completes the in-situ digestion reaction of calcium oxide by adding lignin sulfonate aqueous solution, which can not only increase the specific surface area of ​​the polyamine, but also effectively control the growth direction of calcium hydroxide crystals, promote the directional growth of calcium hydroxide crystals, and increase the probability of contact and reaction between calcium hydroxide active sites and flue gas by "tearing" the polyamine molecular layer through calcium hydroxide crystals. Compared with the adsorbent preparation method of first digesting calcium oxide to generate calcium hydroxide and then loading polyamines, the present invention ensures the directional growth and controllable structure of calcium hydroxide crystals generated after digestion. The adsorbent has a large specific surface area, and a large number of tertiary amine groups and calcium hydroxide active sites on its surface can chemically adsorb SO2 and CO2 in flue gas respectively. Compared with other technologies, the adsorbent obtained by the present invention can sequentially desorb SO2 and CO2 at high temperature, and the desorption processes of SO2 and CO2 do not affect each other, thereby realizing the recycling of sulfur and carbon resources by the adsorbent. In addition, compared with other flue gas sulfur recovery technologies, the preparation method provided by the present invention is simple, efficient, economical and feasible, and the equipment and instruments used have simple requirements and high output, which can effectively reduce investment and operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0029] Figure 1 X-ray diffraction (XRD) diagram of the adsorbent obtained in Examples 1-3 of the present invention;

[0030] Wherein, (a) is Example 1, (b) is Example 2, and (c) is Example 3;

[0031] FIG2 is a scanning electron microscope (SEM) image of the adsorbent particles obtained in Examples 1-3 of the present invention;

[0032] Wherein, (a) is Example 1, (b) is Example 2, and (c) is Example 3;

[0033] FIG3 is a graph showing the change in concentration of the adsorbents obtained in Example 2 of the present invention and Comparative Example 1 during the adsorption and desorption of SO2 and CO2 as a function of reaction time.

[0034] Among them, (a) is Example 2, and (b) is Comparative Example 1. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] The embodiment of the present invention provides a method for preparing a flue gas desulfurization adsorbent capable of recovering sulfur and carbon, comprising the following steps:

[0038] After the polyamine is fully methylated, calcium oxide powder is added to fully impregnate and dry the propanol solution, and then a lignin sulfonate aqueous solution is added thereto, and the calcium oxide digestion process is completed with stirring, and then filtered and roasted to obtain the flue gas desulfurization adsorbent particles capable of recovering sulfur and carbon.

[0039] S1. Continuously stir the polyamine, formaldehyde and formic acid under a nitrogen atmosphere, add ammonia water to the polyamine after the polyamine is fully methylated, and remove the formaldehyde, water and ammonia water by rotary evaporation. Add propanol to the liquid product after rotary evaporation, take the supernatant after centrifugation, and obtain a propanol solution of the methylated polyamine;

[0040] S2, adding calcium oxide powder to the solution obtained after step S1, stirring and mixing thoroughly to achieve full impregnation of the methylated polyamine with calcium oxide particles, and obtaining a solid phase product after drying;

[0041] S3. Pour the lignin sulfonate aqueous solution into the solid phase product obtained after the end of step S2, and complete the digestion process of calcium oxide with stirring. The obtained paste can be washed with deionized water and filtered to obtain solid particles, which are placed in a tubular furnace under an inert atmosphere for roasting to obtain the flue gas desulfurization adsorbent particles capable of recovering sulfur and carbon.

[0042] In some preferred embodiments, the mass ratio of the polyamine to calcium oxide is 0.05-10:1; in some more preferred embodiments, the mass ratio of the polyamine to calcium oxide is 0.5:1.

[0043] In some preferred embodiments, the polyamine includes at least one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine; in some more preferred embodiments, the polyamine is tetraethylenepentamine.

[0044] In some preferred embodiments, the mass percentage of the lignin sulfonate aqueous solution is 0.02% to 10%, and the mass ratio of lignin sulfonate to calcium oxide is 0.005 to 2:1; in some more preferred embodiments, the mass percentage of the lignin sulfonate aqueous solution is 0.25%, and the mass ratio of lignin sulfonate to calcium oxide is 0.03:1.

[0045] In some preferred embodiments, the lignin sulfonate includes at least one of sodium lignin sulfonate, magnesium lignin sulfonate, and calcium lignin sulfonate.

[0046] In some preferred embodiments, during the digestion of calcium oxide by the aqueous solution of lignin sulfonate, the digestion temperature is 30 to 120° C., and the digestion time is 15 minutes to 3 hours.

[0047] In some preferred embodiments, the roasting temperature of the product after the digestion reaction of lignin sulfonate with calcium oxide is 90-350° C., and the roasting time is 30 minutes to 3 hours.

[0048] After the methylation reaction, the primary amine and secondary amine groups in the polyamine are converted into tertiary amines. Tertiary amines can chemically adsorb SO2, but the chemical adsorption amount of CO2 in flue gas is very low, and it has a high SO2 selectivity. The polyamine after the methylation reaction is loaded on the outer surface of the calcium oxide particles, and the in-situ digestion reaction of calcium oxide is completed by adding a lignin sulfonate aqueous solution, which increases the specific surface area of ​​the polyamine, and can effectively control the growth direction of the calcium hydroxide crystals. The polyamine molecular layer is "torn" by the calcium hydroxide crystals, and the probability of contact and reaction between the active sites of calcium hydroxide and the flue gas is increased. A large number of tertiary amine groups and calcium hydroxide active sites on the surface of the adsorbent can chemically adsorb SO2 and CO2 in the flue gas respectively. The adsorbent obtained by the present invention can sequentially desorb SO2 and CO2 at high temperature, and the desorption processes of SO2 and CO2 are independent of each other. Therefore, the adsorbent prepared by the embodiment of the present invention can realize the recycling of sulfur and carbon resources by the adsorbent.

[0049] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0050] Example 1

[0512] A method for preparing a flue gas desulfurization adsorbent capable of recovering sulfur and carbon comprises the following steps:

[0005] (1) Nitrogen was continuously introduced into a three-necked flask to replace the air therein, 1.5 g of tetraethylenepentamine was added thereto, 18 mL of formaldehyde and 25 mL of formic acid were added dropwise under a nitrogen atmosphere, and the mixture was heated in an oil bath at 120° C. for 15 hours, followed by the addition of 20 mL of aqueous ammonia. All products were transferred to a rotary evaporator and rotary evaporated at 60° C. to remove liquid impurities. Since the remaining product contained solid impurities, it was washed with propanol and separated by a centrifuge. The supernatant after centrifugation was the propanol solution of methylated tetraethylenepentamine;

[0053] (2) Add 3 g of calcium oxide powder to the solution obtained after step S1, place it in a magnetic stirrer and stir to fully mix the two, stir for 30 minutes, dry the product in a vacuum drying oven at 80° C. for 2 hours, and collect the solid phase product after drying;

[0054] (3) Pour 25 g of a 0.25% by mass calcium lignin sulfonate aqueous solution into the solid phase product obtained after step S2, and keep stirring continuously at 80° C. for 1 hour to complete the digestion process of calcium oxide. After washing the obtained paste with deionized water and filtering it with suction, put it into a tubular furnace under an inert atmosphere and keep it at 200° C. for 1 hour to obtain the flue gas desulfurization adsorbent particles capable of recovering sulfur and carbon, which are recorded as adsorbent-1.

[0055] Example 2

[0056] A method for preparing a flue gas desulfurization adsorbent capable of recovering sulfur and carbon comprises the following steps:

[0057] (1) Nitrogen was continuously introduced into a three-necked flask to replace the air therein, 1.5 g of tetraethylenepentamine was added thereto, 18 mL of formaldehyde and 25 mL of formic acid were added dropwise under a nitrogen atmosphere, and the mixture was heated in an oil bath at 120° C. for 15 hours, followed by the addition of 20 mL of aqueous ammonia. All products were transferred to a rotary evaporator and rotary evaporated at 60° C. to remove liquid impurities. Since the remaining product contained solid impurities, it was washed with propanol and separated by a centrifuge. The supernatant after centrifugation was the propanol solution of methylated tetraethylenepentamine;

[0058] (2) Add 3 g of calcium oxide powder to the solution obtained after step S1, place it in a magnetic stirrer and stir to fully mix the two, stir for 30 minutes, dry the product in a vacuum drying oven at 80° C. for 2 hours, and collect the solid phase product after drying;

[0059] (3) Pour 37 g of 0.25% by mass calcium lignin sulfonate aqueous solution into the solid phase product obtained after step S2, and keep stirring continuously at 80° C. for 1 hour to complete the digestion process of calcium oxide. After washing the obtained paste with deionized water and filtering it with suction, put it into a tubular furnace under an inert atmosphere and keep it at 200° C. for 1 hour to obtain the flue gas desulfurization adsorbent particles capable of recovering sulfur and carbon, which are recorded as adsorbent-2.

[0060] Example 3

[0061] A method for preparing a flue gas desulfurization adsorbent capable of recovering sulfur and carbon comprises the following steps:

[0062] (1) Nitrogen was continuously introduced into a three-necked flask to replace the air therein, 1.5 g of tetraethylenepentamine was added thereto, 18 mL of formaldehyde and 25 mL of formic acid were added dropwise under a nitrogen atmosphere, and the mixture was heated in an oil bath at 120° C. for 15 hours, followed by the addition of 20 mL of aqueous ammonia. All products were transferred to a rotary evaporator and rotary evaporated at 60° C. to remove liquid impurities. Since the remaining product contained solid impurities, it was washed with propanol and separated by a centrifuge. The supernatant after centrifugation was the propanol solution of methylated tetraethylenepentamine;

[0063] (2) Add 3 g of calcium oxide powder to the solution obtained after step S1, place it in a magnetic stirrer and stir to fully mix the two, stir for 30 minutes, dry the product in a vacuum drying oven at 80° C. for 2 hours, and collect the solid phase product after drying;

[0064] (3) Pour 50 g of a 0.25% by mass calcium lignin sulfonate aqueous solution into the solid phase product obtained after step S2, and keep stirring continuously at 80° C. for 1 hour to complete the digestion process of calcium oxide. After washing the obtained paste with deionized water and filtering it with suction, put it into a tubular furnace under an inert atmosphere and keep it at 200° C. for 1 hour to obtain the flue gas desulfurization adsorbent particles capable of recovering sulfur and carbon, which are recorded as adsorbent-3.

[0065] Comparative Example 1

[0066] A method for preparing a flue gas desulfurization adsorbent comprises the following steps:

[0067] (1) Nitrogen was continuously introduced into a three-necked flask to replace the air therein, 1.5 g of tetraethylenepentamine was added thereto, 18 mL of formaldehyde and 25 mL of formic acid were added dropwise under a nitrogen atmosphere, and the mixture was heated in an oil bath at 120° C. for 15 hours, followed by the addition of 20 mL of aqueous ammonia. All products were transferred to a rotary evaporator and rotary evaporated at 60° C. to remove liquid impurities. Since the remaining product contained solid impurities, it was washed with propanol and separated by a centrifuge. The supernatant after centrifugation was the propanol solution of methylated tetraethylenepentamine;

[0068] (2) Add 3 g of resin particles to the solution obtained after step S1, place it in a magnetic stirrer and stir to fully mix the two. After stirring for 30 minutes, dry the product in a vacuum drying oven at 80°C for 2 hours. After drying, collect the solid phase product and record it as adsorbent-4.

[0069] Performance Testing

[0070] 1. The adsorbent materials prepared in Examples 1-3 were characterized by X-ray diffraction (XRD). The characterization results are as follows: Figure 1 shown. Figure 1 Among them, (a) is Example 1, (b) is Example 2, and (c) is Example 3.

[0071] Will Figure 1 Comparison of the middle curves (a), (b) and (c) shows that the characteristic peaks of the three are consistent with the characteristic peaks on the PDF card of calcium hydroxide, indicating that polyamines such as tetraethylenepentamine do not have a crystal structure and cannot be detected by XRD characterization. Examples 1-3 all contain calcium hydroxide crystals. Figure 1 The characteristic peak intensities of the middle curves (a), (b), and (c) increase successively, indicating that as the amount of calcium lignin sulfonate added increases, more calcium hydroxide crystals grow in a directional manner and "tear" the tetraethylenepentamine layer, and the specific surface area of ​​the calcium hydroxide crystals exposed on the adsorbent surface gradually increases.

[0072] 2. The adsorbents prepared in Examples 1-3 were characterized by scanning electron microscopy (SEM), and the characterization results are shown in Figure 2. In Figure 2, (a) is Example 1, (b) is Example 2, and (c) is Example 3.

[0073] Comparing the various parts of the accompanying drawings in Figure 2, it can be seen that calcium lignin sulfonate has a regulating effect on the apparent morphology of the adsorbent particles. Comparing Example 1, Example 2 and Example 3, it is found that the introduction of a small amount of calcium lignin sulfonate is not enough to make the calcium hydroxide crystals grow and "tear" the tetraethylene pentamine layer. At this time, the tetraethylene pentamine layer wrapped on the outer surface of the calcium hydroxide crystals is thicker, and the exposed surface area of ​​the calcium hydroxide crystals is smaller. With the increase in the amount of calcium lignin sulfonate used, the calcium hydroxide crystals grow larger and larger, and the thickness of the tetraethylene pentamine layer becomes thinner until it is "torn". When the amount of calcium lignin sulfonate used is too high, as shown in Figure 2 (c), the growth of the calcium hydroxide crystals is unstable, forming a messy crystal structure. Figure 2 (b) shows that the appropriate amount of calcium lignin sulfonate used can effectively increase the specific surface area of ​​the adsorbent and improve the adsorption efficiency of the adsorbent for SO2 and CO2.

[0074] 3. The adsorbents prepared in Examples 1-3 were characterized by nitrogen adsorption-desorption, and the specific surface area of ​​the prepared adsorbents was measured. The BET data of the adsorbents prepared in Examples 1-3 are shown in Table 1:

[0075] Table 1

[0076] It can be seen from Table 1 that the specific surface areas of the calcium-based adsorbents obtained in Examples 1, 2, and 3 are 23.47 m 2 / g, 42.66m 2 / g and 21.85m 2 / g. This indicates that the appropriate mass ratio of calcium lignin sulfonate to calcium oxide is beneficial to increasing the specific surface area of ​​the adsorbent, thereby improving its adsorption performance for SO2 and CO2.

[0077] 4. The adsorbents prepared in Example 2 and Comparative Example 1 were tested for their adsorption and desorption performance of SO2 and CO2 in flue gas. The test results are shown in (a) and (b) of Figure 3. Specifically, the adsorption reaction conditions of SO2 and CO2 during the test were: dry basis SO2 concentration 700 mg / Nm 3 , dry basis NOx concentration 300mg / Nm 3 , CO2 volume concentration of 10%, O2 volume concentration of 5%, water vapor volume concentration of 8%, N2 as balance gas, simulated flue gas flow rate of 280mL / min, adsorbent loading of 0.5g, adsorption reaction temperature of 90℃. During the test, the SO2 and CO2 desorption reaction conditions were: N2 volume concentration of 100%, simulated flue gas flow rate of 280mL / min, adsorbent loading of 0.5g, and the desorption reaction temperature was programmed from 60℃ to 155℃ at a heating rate of 2.5℃ / min, and then programmed to 305℃ at a heating rate of 5℃ / min. The SO2 and CO2 concentrations during the reaction were detected by an infrared flue gas analyzer, the adsorption performance of the adsorbent was evaluated by the SO2 and CO2 penetration time, and the desorption performance of the adsorbent was evaluated by the peak area of ​​SO2 and CO2 concentrations. In Figure 3, C in the vertical axis refers to the SO2 and CO2 concentrations detected by the infrared flue gas analyzer at a certain moment of the reaction, and C0 refers to the SO2 and CO2 concentrations in the simulated flue gas detected by the infrared flue gas analyzer when the adsorbent dosage is zero.

[0078] As can be seen from Figure 3, compared with comparative example 1 using resin particles to load methylated tetraethylenepentamine, the adsorbent obtained by the present invention effectively improves the adsorption amount of SO2 and CO2 by the adsorbent, and prolongs the penetration time of SO2 and CO2 by the adsorbent. The adsorbent obtained by the present invention can sequentially desorb SO2 and CO2 under programmed temperature conditions, and the desorption processes of SO2 and CO2 are independent of each other, which conveniently realizes the recycling of sulfur and carbon resources by the adsorbent.

[0079] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, shall make equivalent replacements or changes according to the technical solution and its concept of the present invention, which shall be included in the protection scope of the invention. Therefore, the protection scope of this application shall be based on the protection scope of the claims.

Claims

1. A flue gas desulfurization adsorbent capable of recovering sulfur and carbon and a preparation method thereof, characterized in that: The following steps are involved: (1) In a nitrogen atmosphere, polyamine, formaldehyde and formic acid are continuously stirred, and after the polyamine is fully methylated, ammonia water is added thereto, and formaldehyde, water and ammonia water are removed by rotary evaporation. Propanol is added to the liquid product after rotary evaporation, and the supernatant is collected after centrifugation to obtain a propanol solution of the methylated polyamine; (2) Adding calcium oxide powder to the obtained propanol solution of the methylated polyamine, stirring and mixing thoroughly to achieve full impregnation of the methylated polyamine with the calcium oxide particles, and drying to obtain a solid phase product.

2. The method according to claim 1, characterized in that The mass ratio of polyamine to calcium oxide is 0.05-10:

1.

3. The method according to claims 1 and 2, characterized in that The polyamine includes at least one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine.

4. The method according to claim 1, characterized in that The mass percentage of the lignin sulfonate aqueous solution is 0.02% to 10%, and the mass ratio of the lignin sulfonate to calcium oxide is 0.005 to 2:

1.

5. The method according to claims 1 and 4, characterized in that The lignin sulfonate includes at least one of sodium lignin sulfonate, magnesium lignin sulfonate and calcium lignin sulfonate.

6. The method according to claim 1, characterized in that During the digestion of calcium oxide by the aqueous solution of lignin sulfonate, the digestion temperature is 30 to 120° C. and the digestion time is 15 minutes to 3 hours.

7. The method according to claim 1, characterized in that The roasting temperature of the product after the digestion reaction of lignin sulfonate with calcium oxide is 90-350° C., and the roasting time is 30 minutes-3 hours.

8. The flue gas desulfurization adsorbent capable of recovering sulfur and carbon as claimed in any one of claims 1 to 7 and the flue gas desulfurization adsorbent capable of recovering sulfur and carbon prepared by the preparation method thereof.

9. Use of the flue gas desulfurization adsorbent capable of recovering sulfur and carbon as claimed in claim 8 in recovering sulfur and carbon in flue gas.

Images