Activated carbon material, its preparation method and application, and method for removing and recycling sulfur dioxide in sulfur-containing waste gas

Abstract

The application relates to the technical field of waste gas treatment, and discloses an activated carbon material, a preparation method and application thereof, and a method for removing and recycling sulfur dioxide in sulfur-containing waste gas. The CO2-TPD test spectrum of the activated carbon material simultaneously contains weak alkaline centers in the range of 80-120 DEG C and medium-strong alkaline centers in the range of 180-260 DEG C, the maximum peak height in the range of 180-260 DEG C is greater than 2000 muV; the activated carbon material has a pore volume ratio of macropores (greater than 100 nm) of more than 70%, an ash content of less than 2%, a high desulfurization rate, good regeneration performance, a SO2 removal rate of more than 99.5%, and an activity stability of more than 99% in 1000 hours.

Description

Technical Field

[0001] This invention relates to the field of waste gas treatment technology, specifically to an activated carbon material, its preparation method and application, and a method for removing and recycling sulfur dioxide from sulfur-containing waste gas. Background Technology

[0002] SO2, as a major air pollutant, has received widespread attention. SO2 damages plant physiology and slows the growth of crops and trees; high concentrations of SO2, if inhaled, can severely irritate the respiratory tract. SO2 is also a primary cause of acid rain. Reports indicate that SO2 emissions have caused acid rain damage to 40% of my country's land area, resulting in annual losses of up to 110 billion yuan. Therefore, controlling and reducing SO2 emissions is a crucial task for the sustainable economic and social development of my country.

[0003] SO2-containing waste gas is generated from industrial heating furnace flue gas, sulfur tail gas, and catalytic cracking regeneration flue gas. With increasingly stringent environmental regulations, SO2 emission reduction is becoming increasingly urgent. Currently, domestic and international SO2 waste gas treatment technologies are mainly divided into two categories: wet and dry methods. Wet methods use liquid absorbents, emulsion absorbents, or absorbent solutions to treat the waste gas, while dry methods use powdered or granular adsorbents, absorbents, or catalysts to remove sulfur dioxide from the flue gas. The most representative and fastest-growing wet desulfurization technology is alkaline scrubbing desulfurization, such as DuPont. TM BELCO's LABSORB TM The technology, employing alkaline washing wet desulfurization, can achieve 50 mg / m³. 3 While alkaline desulfurization processes achieve lower emissions, they generate new secondary pollutants—sodium sulfate-containing wastewater. This wastewater cannot be directly discharged, and further treatment requires substantial investment. Therefore, alkaline desulfurization is significantly restricted, and many companies have begun to prohibit the addition of new alkaline desulfurization processes. Dry desulfurization, due to its simple operation, low equipment investment, and lack of secondary pollution, has developed rapidly in recent years and is considered the most promising desulfurization process. However, its development is limited by adsorbents, as the process demands high-quality adsorbents with both high sulfur capacity and good regenerability. Therefore, it is necessary to explore a new method for treating SO2-containing waste gas to solve the problem of achieving SO2 emission standards in domestic industrial tail gas.

[0004] Activated carbon is a highly absorbent carbon obtained from raw materials such as coal, wood, and fruit shells through high-temperature (300–400℃) carbonization and oxygen-deficient activation (920–960℃) treatment. The inherent hydrophobicity, nonpolarity, and thermal stability of activated carbon make it easily modifiable and activated during use, resulting in unique surface chemistry and pore structure that further enhance its loading capacity and adsorption performance. Activated carbon has a well-developed pore structure and a large specific surface area; the micropore surface area, which controls the adsorption capacity, accounts for over 95% of the total surface area, effectively adsorbing sulfur-containing compounds such as SO2.

[0005] CN1313201C discloses a supported activated carbon catalyst and its preparation method. Activated carbon is used as a support, and additional components are loaded onto the activated carbon support using an impregnation method. The added components are distributed on most of the pore surface of the activated carbon, and the added components account for 0.01%-50% of the weight of the adsorbent. This catalyst mainly removes sulfur dioxide through adsorption, with an SO2 adsorption capacity of up to 16.9%, but the degree of SO2 removal is not mentioned.

[0006] CN111036242A discloses a vanadium-based catalyst and its preparation method. The catalyst can catalytically convert SO2 into SO3. However, vanadium is a toxic metal, which makes the catalyst cost high and causes some secondary pollution during the preparation process.

[0007] CN104549143A discloses an activated carbon desulfurization adsorbent and its preparation method. The activated carbon is modified and prepared into a solid adsorbent by using salts containing metals such as Al, Zn, and Ni and H3PO4 as additives. The adsorbent mainly removes hydrogen sulfide, COS, methanethiol and other substances from the gas through adsorption, but it cannot be used to catalyze the conversion of sulfur dioxide to sulfur trioxide.

[0008] In summary, although some desulfurization catalysts and their preparation methods have been reported, problems such as low sulfur removal rate, complex preparation process, and poor application effect still exist in practical applications. Summary of the Invention

[0009] The purpose of this invention is to overcome the problems existing in the prior art and provide an activated carbon material, its preparation method and application, as well as a method for removing and recycling sulfur dioxide from sulfur-containing waste gas. The activated carbon material provided by this invention has a high desulfurization rate and good regeneration performance, with an SO2 removal rate greater than 99.5% and an activity stability greater than 99% after 1000 hours.

[0010] To achieve the above objectives, the present invention provides an activated carbon material in which the CO2-TPD test spectrum simultaneously contains weakly basic centers in the range of 80-120℃ and moderately strong basic centers in the range of 180-260℃, with the maximum peak height in the range of 180-260℃ exceeding 2000μV; the activated carbon material contains more than 70% of the pore volume of macropores larger than 100nm and has an ash content of less than 2%.

[0011] A second aspect of the present invention provides a method for preparing activated carbon material, the method comprising:

[0012] (1) Carbonize the activated carbon raw material;

[0013] (2) The carbonized activated carbon raw material, binder, and alkaline nitrogen-containing compound are mixed and molded.

[0014] (3) Activate, wash and dry the molding material.

[0015] A third aspect of the present invention provides activated carbon materials prepared by the preparation method described herein.

[0016] The fourth aspect of the present invention provides the application of the activated carbon material of the present invention in adsorption desulfurization, preferably in the removal of sulfur dioxide from sulfur-containing waste gas.

[0017] The fifth aspect of the present invention provides a method for removing and recycling sulfur dioxide from sulfur-containing waste gas, the method comprising: contacting the sulfur-containing waste gas with the activated carbon material described in the present invention for adsorption and desulfurization.

[0018] The activated carbon material provided by this invention can catalyze the conversion of SO2 to SO3 at low temperatures, exhibiting a high desulfurization rate (SO2 removal rate greater than 99.5%). Furthermore, the catalyst has a high macroporous content and numerous basic centers, making it easy to regenerate through water washing, thus maintaining high activity stability and good regeneration performance; its activity stability is greater than 99% after 1000 hours. In addition, the activated carbon material provided by this invention has a low ash content, significantly reducing catalyst wear. Simultaneously, it can be quickly recycled after the catalyst reaches the end of its service life, effectively conserving carbon resources.

[0019] The method for removing and recovering sulfur dioxide from sulfur-containing waste gas provided by this invention can effectively recover sulfur resources, and the device has high operational stability. This method can regenerate the catalyst simultaneously with the reaction of SO2 to SO3, eliminating the need for a separate regeneration reactor or regeneration section. The further generated dilute sulfuric acid can be recovered and reused. In summary, this invention provides a clean, pollution-free, and environmentally compliant method for treating sulfur-containing waste gas, achieving SO2 emissions of less than 50 mg / Nm³ after purification. 3It can meet the requirements of environmental protection regulations and contribute to environmental protection. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of the preparation of activated carbon material (also called catalyst) according to one embodiment of the present invention;

[0021] Figure 2 This is a pore distribution test diagram of the activated carbon material prepared in Example 1;

[0022] Figure 3 This is a test diagram of the distribution of alkaline centers in the activated carbon material prepared in Example 1;

[0023] Figure 4 This is a stability test diagram of the activated carbon material prepared in Example 1;

[0024] Figure 5 This is a stability test diagram of the activated carbon material prepared in Comparative Example 3;

[0025] Figure 6 This is a process flow diagram of the micro-reaction evaluation device for activated carbon materials. Detailed Implementation

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0027] This invention provides an activated carbon material in which both weakly basic centers exist in the range of 80-120℃ and moderately strong basic centers exist in the range of 180-260℃ in the CO2-TPD test spectrum, with the maximum peak height in the 180-260℃ range exceeding 2000μV; the activated carbon material has a pore volume ratio of macropores larger than 100nm of more than 70%, and an ash content of less than 2%.

[0028] According to a preferred embodiment of the present invention, the pore volume ratio of macropores larger than 100 nm is 70-80%.

[0029] In this invention, the specific surface area of ​​the activated carbon material can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the specific surface area of ​​the activated carbon material is 1000 m². 2 / g or more, preferably 1200-1300m 2 / g.

[0030] In this invention, the pore volume of the activated carbon material can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the pore volume of the activated carbon material is above 0.6 mL / g, preferably 0.7-0.9 mL / g.

[0031] In this invention, the form of activated carbon material is selected and determined according to the reaction requirements. It can be used in a molded structure. According to one embodiment of this invention, the activated carbon material is a molded structure material. Preferably, the molded structure material contains 2-6 wt% binder oxide, and more preferably, the binder oxide is silicon dioxide.

[0032] The aforementioned preferred activated carbon material has a large number of active reaction sites, which is conducive to the catalytic conversion of sulfur dioxide. Furthermore, the sulfuric acid that is ultimately generated and accumulated in the pores of the activated carbon material is easily washed out and removed after water washing, giving the activated carbon material the advantage of easy regeneration.

[0033] Activated carbon materials possessing the aforementioned characteristics can all achieve the objectives of this invention. There are no special requirements for their preparation methods. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the preparation method of the activated carbon material includes:

[0034] (1) Carbonize the activated carbon raw material;

[0035] (2) The carbonized activated carbon raw material, binder, and alkaline nitrogen-containing compound are mixed and molded.

[0036] (3) Activate, wash and dry the molding material.

[0037] In this invention, there are no special requirements for the type of activated carbon raw material. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the activated carbon raw material is one or more of coal-based activated carbon, wood-based activated carbon, and fruit shell activated carbon, preferably fruit shell activated carbon, such as coconut shell activated carbon.

[0038] In this invention, the specific surface area of ​​the activated carbon raw material can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the specific surface area of ​​the activated carbon raw material is 800 m². 2 / g or more, preferably 900-1100m 2 / g.

[0039] In this invention, in order to remove non-carbon components from activated carbon raw materials, the carbonization needs to be carried out in an oxygen-free atmosphere, preferably in an inert atmosphere. There are no special requirements for the type of inert gas, and common inert gases are applicable to this invention. For example, carbonization can be carried out in a nitrogen atmosphere.

[0040] In this invention, the carbonization temperature can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the carbonization temperature is 600-700℃, preferably 630-660℃.

[0041] In this invention, the carbonization time can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the carbonization time is 3-8 hours, preferably 6-7 hours.

[0042] In this invention, there are no special requirements for the instruments used in the carbonization process. Common instruments and equipment that can be used for carbonization are applicable to this invention. For example, a tube furnace can be used to carbonize the raw materials.

[0043] In this invention, there are no special requirements for the type of binder. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the binder is an alkaline binder, preferably one or more of water glass, sodium citrate, and silica sol, more preferably silica sol, with a preferred solid content of 30-40 wt%. Using the aforementioned preferred binder is beneficial for the subsequent extrusion molding of the catalyst, and can increase the number of alkaline active centers on the surface of the activated carbon material and help increase the adsorption pore volume.

[0044] In this invention, a wide range of alkaline nitrogen-containing compounds can be selected. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the alkaline nitrogen-containing compound is one or more of inorganic ammonia and organic amines, more preferably one or more of urea, thiourea, ammonia water, and melamine. Using the aforementioned preferred alkaline nitrogen-containing compounds helps to increase the number of alkaline centers in the activated carbon material.

[0045] In this invention, the weight ratio of alkaline nitrogen-containing compound to activated carbon raw material can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the weight ratio of alkaline nitrogen-containing compound to activated carbon raw material is 5-30:100, preferably 10-15:100.

[0046] In this invention, the weight ratio of binder to activated carbon raw material can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the weight ratio of binder to activated carbon raw material is 2-20:100, preferably 12-18:100.

[0047] In this invention, the content of carbonized activated carbon raw material in the slurry after mixing carbonized activated carbon raw material, binder, and alkaline nitrogen-containing compound has a wide range of selectable values. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the content of carbonized activated carbon raw material in the slurry after mixing carbonized activated carbon raw material, binder, and alkaline nitrogen-containing compound is 60-80 wt%.

[0048] In this invention, to facilitate subsequent extrusion molding, a solvent can be added to the mixed slurry of carbonized activated carbon raw material, binder, and alkaline nitrogen-containing compound to ensure uniform mixing of the substances. There are no special requirements for the type of solvent; for example, water can be used as a solvent. There are no special requirements for the amount of solvent used; it can be selected according to actual needs, as long as it can fully dissolve and uniformly mix the substances. Further details are omitted here.

[0049] In this invention, there are no special requirements for the molding method of the activated carbon material. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the activated carbon material is formed by extrusion.

[0050] In this invention, there are no special requirements for the extrusion type. Commonly used extrusion types can be selected according to actual needs. For example, φ4 templates can be used on an extrusion machine to form φ4×3-10 activated carbon strips.

[0051] In this invention, the method for preparing activated carbon material further includes: crushing the carbonized activated carbon raw material to 60 mesh or higher before step (2). Adopting the aforementioned preferred scheme is beneficial for the subsequent extrusion molding of the activated carbon material.

[0052] In this invention, there are no special requirements for the crushing equipment. Commonly used crushers are all applicable to this invention. Those skilled in the art can select according to actual needs, which will not be elaborated here.

[0053] According to a preferred embodiment of the present invention, the activation is carried out in an oxygen-free atmosphere, preferably in an inert atmosphere. There are no special requirements for the type of inert gas; common inert gases are applicable to the present invention and can be selected according to the actual situation. For example, activation can be carried out in a nitrogen atmosphere.

[0054] According to a preferred embodiment of the present invention, the activation is carried out in the presence of potassium-containing vapor. The activation is achieved by injecting potassium-containing vapor at high temperature. The main purpose of the activation is to increase the proportion of macropores above 100 nm in the activated carbon material. Pore formation is achieved by introducing potassium-containing vapor at a higher temperature.

[0055] In this invention, there are no special requirements for the type of potassium-containing steam. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the potassium-containing steam is one or more of potassium hydroxide steam, potassium bromide steam, and potassium chloride steam, preferably potassium hydroxide steam.

[0056] In this invention, the concentration of potassium vapor in the activation gas stream can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the concentration of potassium vapor in the activation gas stream is 0.05-0.15 mol / L.

[0057] In this invention, the activation temperature can be selected over a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the activation temperature is 900-1000℃, preferably 930-970℃.

[0058] In this invention, the activation time can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the activation time is 4-10 hours, preferably 5-6 hours.

[0059] In this invention, there are no special requirements for the equipment used in the activation process. Common equipment that can be used for activation is applicable to this invention and will not be described in detail here. For example, activation can be carried out in a tube furnace.

[0060] The washing process described in this invention has no special requirements. According to a preferred embodiment of this invention, the washing process includes acid washing, water washing and alkaline washing performed in sequence.

[0061] In this invention, there are no special requirements for the number of pickling cycles. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the pickling is performed 2-3 times.

[0062] In this invention, the pH of the acid solution used for pickling is not particularly required. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the pH of the acid solution is 1-2.

[0063] In this invention, there are no special requirements for the type of acid solution. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the acid solution is one or more of sulfuric acid, hydrochloric acid, and nitric acid, preferably hydrochloric acid.

[0064] In this invention, there are no special requirements for pickling time, which can be selected according to actual needs. For example, the pickling time can be selected as 7-10 hours.

[0065] The purpose of acid washing in this invention is to remove heavy metal ions from activated carbon materials, thereby reducing the ash content of activated carbon materials, improving the wear resistance of activated carbon materials, and reducing the pressure drop of activated carbon material bed.

[0066] In this invention, there are no special requirements for the number of washes. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the washes are performed 3-4 times.

[0067] In the water washing process of this invention, there are no special requirements for the pH of the solution after washing. The purpose of this invention can be achieved as long as the pH of the solution is close to neutral. The appropriate pH can be selected according to actual needs. For example, the water washing process can be carried out until the pH of the solution is in the range of 7-9.

[0068] The purpose of water washing in this invention is to remove the acid residue from the pickling process in order to facilitate the subsequent alkaline washing process.

[0069] In this invention, there are no special requirements for the number of alkaline washes. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the alkaline wash is performed 3-4 times.

[0070] In this invention, the pH of the alkaline solution used for alkaline washing is not particularly required. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the pH of the alkaline solution is 12-13.

[0071] In this invention, there are no special requirements for the type of alkali used in the alkaline washing. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the alkali is one or more of potassium hydroxide, calcium hydroxide, and sodium hydroxide, preferably sodium hydroxide.

[0072] In this invention, there are no special requirements for the alkaline washing time, which can be selected according to actual needs. For example, the alkaline washing time can be selected as 7-10 hours.

[0073] The purpose of alkaline washing in this invention is to modify activated carbon materials with alkali, so that the activated carbon materials have more alkaline centers, thereby improving the catalytic activity of the activated carbon materials.

[0074] In this invention, the activated carbon material needs to be dried after washing. There are no special requirements for the drying conditions, and commonly used drying methods can achieve the purpose of this invention. Those skilled in the art can choose according to actual needs, which will not be elaborated here.

[0075] In this invention, the dried shaped activated carbon material can be crushed and shaped according to actual production needs, so as to facilitate the removal of the reaction products generated in the activated carbon material and make the activated carbon material easy to regenerate. There are no special requirements for the shaping size, which depends on the actual situation of the device. For example, it can be shaped to 4-8 mesh.

[0076] This invention provides activated carbon materials prepared by the method described herein. The activated carbon materials provided by this invention exhibit high desulfurization rates and good regeneration performance.

[0077] This invention provides the application of the activated carbon material described herein in adsorption desulfurization, preferably in the removal of sulfur dioxide from sulfur-containing waste gas.

[0078] This invention provides a method for removing and recycling sulfur dioxide from sulfur-containing waste gas. The method includes: contacting the sulfur-containing waste gas with the activated carbon material described in this invention for adsorption and desulfurization.

[0079] According to a preferred embodiment of the present invention, the contact is carried out in the presence of demineralized water. Using the aforementioned preferred embodiment, by spraying demineralized water, sulfur trioxide generated from the reaction of sulfur dioxide and oxygen in the sulfur-containing waste gas further reacts with water to generate dilute sulfuric acid, thereby achieving the recovery and utilization of sulfur resources.

[0080] In this invention, the volumetric composition of each component in the sulfur-containing waste gas can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the sulfur-containing waste gas contains: less than 0.15% SO2, 3-15% O2, 5-20% water by volume, and an inert gas. The inert gas is generally N2.

[0081] In this invention, the gas volume hourly space velocity (VHSV) of the sulfur-containing waste gas can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the VHSV of the sulfur-containing waste gas is 1500-4000 h⁻¹. -1 .

[0082] In this invention, the temperature range for adsorption desulfurization is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the temperature for adsorption desulfurization is 30-100℃.

[0083] According to a preferred embodiment of the present invention, the method for removing and recycling sulfur dioxide in sulfur-containing waste gas provided by the present invention can achieve an SO2 conversion rate of over 99.5%.

[0084] In this invention, when sulfur-containing waste gas comes into contact with modified activated carbon material, sulfur dioxide and oxygen are adsorbed onto the active sites of the activated carbon material. The adsorbed sulfur dioxide reacts with oxygen to generate adsorbed sulfur trioxide, thereby achieving the removal of sulfur dioxide. Subsequently, by spraying a certain amount of demineralized water onto the reactor bed, the sulfur trioxide in the pores of the activated carbon material reacts with water to generate sulfuric acid. After the generated sulfuric acid is washed out with water, the active sites in the pores of the activated carbon material can catalyze the oxidation of new SO2. Therefore, the method for removing and recovering sulfur dioxide from sulfur-containing waste gas provided by this invention can operate continuously, thereby achieving efficient desulfurization and effective recovery of sulfur resources.

[0085] The specific desulfurization principle of this invention is as follows:

[0086] SO2 + C → C-SO2 (1)

[0087] O2 + C → C-O2 (2)

[0088] 2C-SO2 + C-O2 → 2C-SO3 (3)

[0089] SO3 + H2O → H2SO4 (4)

[0090] (C represents the active sites on the surface of activated carbon, and - represents adsorption.)

[0091] The method for removing and recovering sulfur dioxide from sulfur-containing waste gas provided by this invention can regenerate activated carbon materials simultaneously with the reaction of SO2 to SO3, eliminating the need for a separate regeneration reactor or regeneration section. The final 5%-25% concentration dilute sulfuric acid can be recycled. This method is a clean, pollution-free, and environmentally compliant approach to treating sulfur-containing waste gas. It effectively recovers sulfur resources, achieves an SO2 removal rate greater than 99.5%, and reduces SO2 emissions to less than 50 mg / Nm³ after purification. 3 It can meet the requirements of environmental protection regulations and contribute to environmental protection.

[0092] In this invention, the pore distribution of the activated carbon material is determined using the mercury porosimetry method.

[0093] In this invention, the specific surface area and pore volume of the activated carbon material were measured in accordance with GB / T 7702.20-2008.

[0094] In this invention, the ash content of the activated carbon material was determined using the method specified in GB / T 12496.3-1999.

[0095] Determination of the basicity center of activated carbon materials:

[0096] CO2-TPD experiments were conducted on activated carbon materials using a Beijing Bio-Tech PCA-1200 chemisorption analyzer combined with a GAS-100Q quadruple mass spectrometer to investigate the alkalinity of the activated carbon materials. The strength of alkalinity was determined by the CO2 desorption temperature, and the alkalinity was obtained from the peak area of ​​the CO2 desorption peak. Typical procedure: 250 mg of activated carbon material sample was weighed and pretreated at 300 °C under high-purity nitrogen (flow rate 30 mL / min) for 20 min. The temperature was then lowered to room temperature (30 °C), and CO2 (flow rate 30 mL / min, concentration 99.999%) was introduced for adsorption for 30 min. After adsorption, nitrogen was purged for 15 min, and then the temperature was raised to 400 °C for desorption, with a heating rate maintained at 10 °C / min. The CO2 temperature change was recorded using a thermal conductivity detector during the heating process.

[0097] Evaluation and testing methods for activated carbon materials:

[0098] The microreactor was constructed from a stainless steel tube with an inner diameter of 20 mm and placed inside a constant temperature chamber. The adsorbent loading was 20 ml, and the top was filled with quartz sand of the same particle size for mixing and preheating. The SO2 content in the inlet and outlet gases of the reactor was analyzed using an MGA-6 infrared flue gas analyzer.

[0099] The laboratory inlet sulfur-containing waste gas had the following gas volume composition: SO2 0.1%, O2 10%, water 10%, with the remainder being N2, and a gas hourly space velocity (GHSV) of 2500 h⁻¹. -1 The performance of activated carbon materials was evaluated at a reaction temperature of 50℃.

[0100] Using the reaction SO2 + 1 / 2O2 + nH2O = H2SO4 + (n-1)H2O as the index reaction, the catalytic activity of activated carbon materials was investigated, and the SO2 conversion rate η of the activated carbon materials was calculated according to the following formula:

[0101]

[0102] C0 and C1 represent the volume concentrations of SO2 at the inlet and outlet, respectively.

[0103] The process flow of the laboratory micro-reflection evaluation device is as follows: Figure 6 As shown.

[0104] Example 1

[0105] The preparation process of activated carbon materials is as follows Figure 1 As shown, the specific steps include:

[0106] (1) Carbonization: Weigh 1000g of material with a specific surface area of ​​932m² 2 / g of coconut shell activated carbon was placed in a tube furnace and carbonized at 650℃ under a nitrogen atmosphere for 6 hours.

[0107] (2) Crushing: The carbonized activated carbon is placed in a crusher and crushed to 60 mesh.

[0108] (3) Extrusion: Measure 150g of silica sol (solid content 30wt%), weigh 125g of urea and dissolve it in 400mL of water to make a urea solution. Add the above solution to the crushed carbon powder in sequence, knead it thoroughly on the extruder, and then extrude it to form carbon powder. Activated carbon strips.

[0109] (4) Activation: Under a nitrogen atmosphere, the activated carbon strips are placed in a tube furnace and the temperature is set to 950℃ to activate the carbon strips. At the same time, 0.1mol / L potassium hydroxide vapor is injected as an activating agent and the activation time is 6h.

[0110] (5) Washing: The activated carbon strips are sequentially acid-washed, water-washed, and alkali-washed. Acid washing: Hydrochloric acid is used as the washing solution in the acid washing tank to acid wash the activated carbon. The pH of the washing solution is controlled at 2. The washing method is immersion washing. The washing time is 7 hours and the number of washings is 3. Water washing: The activated carbon strips are washed with water in the water washing tank. The washing is 4 times until the pH reaches 7. Alkali washing: The activated carbon strips are washed with sodium hydroxide in the alkali washing tank. The pH of the washing solution is controlled at 13. The washing time is 8 hours and the number of washings is 4.

[0111] (6) Shaping: The strip-shaped activated carbon material is crushed and shaped to a size of 8 mesh.

[0112] The pore distribution of the activated carbon material prepared in Example 1 is shown in the figure. Figure 2 Specific surface area and pore volume are shown in Table 1, and the distribution of alkaline centers is shown in Table 2. Figure 3 It can be seen that the activated carbon material has weakly basic and moderately basic centers in the range of 80-120℃ and 180-260℃, and the maximum peak height in the range of 180-260℃ is greater than 2000μV.

[0113] Examples 2-6

[0114] Following the method of Example 1, only some of the preparation conditions involved in the preparation process were changed. Compared to Example 1, the specific changes in preparation conditions involved in Examples 2-6 are listed in Table 1.

[0115] The distribution of alkaline centers in the activated carbon materials prepared in Examples 2-6 and Figure 3 similar.

[0116] Table 1

[0117]

[0118]

[0119] Comparative Examples 1-6

[0120] Following the method of Example 1, only some preparation conditions involved in the preparation process were changed. The specific changes in preparation conditions involved in Comparative Examples 1-6 are listed in Table 2.

[0121] Table 2

[0122]

[0123]

[0124] Test Example 1

[0125] The activated carbon materials prepared in Examples 1-6 and Comparative Examples 1-6 were tested according to the evaluation and testing methods for activated carbon materials, and the results are listed in Table 3.

[0126] Table 3

[0127]

[0128]

[0129] Test Example 2

[0130] Following the evaluation and testing methods for activated carbon materials, the activated carbon material prepared in Example 1 was subjected to a 1000-hour regeneration stability study. The results are shown below. Figure 4 ,from Figure 4 It can be seen that the conversion rate of activated carbon material is stable at over 99% within 1000 hours, indicating good regeneration stability.

[0131] Test Example 3

[0132] Following the evaluation and testing methods for activated carbon materials, the activated carbon material prepared in Comparative Example 3 was subjected to a 1000-hour regeneration stability study. The results are shown below. Figure 5 ,from Figure 5 It can be seen that the activated carbon material maintains good regeneration stability in the first 200 hours. After 200 hours, the SO2 conversion rate gradually decreases, and the decrease becomes more and more significant as the evaluation time increases.

[0133] The preferred embodiments of the present invention have been described above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An activated carbon material, characterized in that, The CO2-TPD test spectrum of this activated carbon material shows both weakly basic centers in the range of 80-120℃ and moderately strong basic centers in the range of 180-260℃, with the maximum peak height in the range of 180-260℃ being greater than 2000μV; the pore volume ratio of macropores larger than 100nm in the activated carbon material is more than 70%, and the ash content is less than 2%.

2. The activated carbon material according to claim 1, wherein, The pore volume ratio of macropores larger than 100nm is 70-80%; and / or The specific surface area of ​​the activated carbon material is 1000 m². 2 / g or more, preferably 1200-1300m 2 / g; and / or The activated carbon material has a pore volume of 0.6 mL / g or higher, preferably 0.7-0.9 mL / g; and / or The activated carbon material is a molded structural material; preferably, the molded structural material contains 2-6 wt% binder oxide, more preferably, the binder oxide is silicon dioxide.

3. A method for preparing an activated carbon material, characterized in that, The method includes: (1) Carbonize the activated carbon raw material; (2) The carbonized activated carbon raw material, binder, and alkaline nitrogen-containing compound are mixed and molded. (3) Activate, wash and dry the molding material.

4. The preparation method according to claim 3, wherein, In step (1), The activated carbon raw material is one or more of coal-based activated carbon, wood-based activated carbon, and fruit shell activated carbon, preferably fruit shell activated carbon; The specific surface area of ​​the activated carbon raw material is 800 m². 2 / g or more, preferably 900-1100m 2 / g; and / or The carbonization conditions include: The procedure shall be carried out under an oxygen-free atmosphere, preferably under an inert atmosphere; and / or The temperature is 600-700℃, preferably 630-660℃; and / or The time is 3-8 hours, preferably 6-7 hours.

5. The preparation method according to claim 3 or 4, wherein, In step (2), The binder is an alkaline binder, preferably one or more of water glass, sodium citrate, and silica sol, more preferably silica sol, and the silica sol preferably has a solid content of 30-40 wt%; and / or The alkaline nitrogen-containing compound is one or more of inorganic ammonia and organic amines, more preferably one or more of urea, thiourea, ammonia water, and melamine; and / or The weight ratio of alkaline nitrogen-containing compounds to activated carbon raw materials is 5-30:100, preferably 10-15:100; and / or The weight ratio of binder to activated carbon raw material is 2-20:100, preferably 12-18:100; and / or In the slurry composed of carbonized activated carbon raw material, binder, and alkaline nitrogen-containing compounds, the content of carbonized activated carbon raw material is 60-80 wt%; and / or The forming process is extrusion molding; and / or The method also includes crushing the carbonized activated carbon raw material to 60 mesh or above before performing step (2).

6. The preparation method according to any one of claims 3-5, wherein, Activation conditions include: The procedure should be carried out in an oxygen-free atmosphere, preferably in an inert atmosphere. and / or The activation was carried out in the presence of potassium-containing vapor; Preferably, the potassium-containing vapor is one or more of potassium hydroxide vapor, potassium bromide vapor, and potassium chloride vapor, preferably potassium hydroxide vapor; preferably, the concentration of the potassium-containing vapor in the activation gas stream is 0.05-0.15 mol / L; and / or The temperature is 900-1000℃, preferably 930-970℃; and / or The time is 4-10 hours, preferably 5-6 hours.

7. The preparation method according to any one of claims 3-6, wherein, The washing process includes sequential acid washing, water washing, and alkaline washing; Preferably, The pickling conditions include: pickling is performed 2-3 times; and / or the pH of the acid solution is 1-2; and / or the acid solution is one or more of sulfuric acid, hydrochloric acid, and nitric acid, preferably hydrochloric acid; and / or the pickling time is 7-10 hours. and / or Wash with water 3-4 times until the solution pH is 7-9; and / or The conditions for alkaline washing include: alkaline washing is performed 3-4 times; and / or the pH of the alkaline solution is 12-13; and / or the alkaline is one or more of potassium hydroxide, calcium hydroxide, and sodium hydroxide, preferably sodium hydroxide; and / or the alkaline washing time is 7-10 hours.

8. Activated carbon material prepared by the preparation method according to any one of claims 3-7.

9. The application of the activated carbon material according to any one of claims 1, 2, and 8 in adsorption desulfurization, preferably in the removal of sulfur dioxide from sulfur-containing waste gas.

10. A method for removing and recovering sulfur dioxide from sulfur-containing waste gas, characterized in that, The method includes: The sulfur-containing waste gas is contacted with the activated carbon material described in any one of claims 1, 2, and 8 for adsorption and desulfurization. Preferably, The contact is carried out in the presence of desalinated water; and / or The sulfur-containing waste gas contains, by volume, less than 0.15% SO2, 3-15% O2, 5-20% water, and inert gases; and / or The conditions for adsorption desulfurization include: The volumetric space velocity of sulfur-containing waste gas is 1500-4000 h⁻¹. -1 ; and / or Temperature 30-100℃; and / or The SO2 conversion rate is above 99.5%.

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