A preparation method of mesoporous adsorbent, mesoporous adsorbent and application thereof

Abstract

The invention discloses a preparation method of a mesoporous adsorbent, a mesoporous adsorbent and an application thereof, wherein the preparation method comprises the following steps: 1) adding a potassium permanganate solution to pre-treat fly ash, modifying it at room temperature and under ultrasonic wave, taking it out and drying it, and then vacuum calcining it; 2) adding the calcined fly ash to an organic sulfur and nitrogen solution, stirring it, filtering it, vacuum drying it, and calcining it to obtain the mesoporous adsorbent. The mesoporous adsorbent prepared by the method can improve the adsorption capacity and desorption efficiency of organic VOCs, and has wide industrial applicability.

Description

Technical Field

[0001] The invention relates to a mesoporous adsorbent, in particular to a preparation method of the mesoporous adsorbent, the mesoporous adsorbent and application thereof, and belongs to the technical field of waste gas treatment. Background Art

[0002] In recent years, the haze problem in my country has become increasingly serious, seriously affecting human health and the harmonious development of society. Haze is mainly caused by high concentrations of aerosols in the atmosphere, including a large amount of organic aerosols, and volatile organic compounds (VOCs) are important precursors to the formation of organic aerosols. A large amount of VOCs will be generated in the petrochemical, coal chemical, oil storage, transportation and sales processes, as well as the production and use of coatings, inks, adhesives, etc. Therefore, it is urgent to strengthen the research and demonstration application of industrial organic waste gas treatment technology.

[0003] At present, the main treatment methods for volatile organic compounds include adsorption, absorption, combustion, condensation, low-temperature plasma oxidation, biological purification, photocatalytic technology, etc. Among them, adsorption is one of the earliest and most mature technologies. This technology has the advantages of high removal efficiency, low energy consumption, mature process, low operating cost and recoverable adsorbent after desorption. It can be used to purify large-flow low-concentration waste gas. Adsorbent performance is a key factor in determining the quality of VOCs removal. Since adsorbents such as activated carbon are generally non-polar structures, they have poor adsorption performance for polar VOCs molecules such as organic ketones, organic alcohols, and organic ethers, and the adsorbent regeneration process usually requires high energy consumption. For example, patent CN2111070117U uses thermal nitrogen regeneration, CN213348299U uses hot steam desorption, and CN112569916A uses vacuum thermal desorption. How to prepare adsorbents suitable for polar VOCs and room temperature desorption through modification is particularly critical.

[0004] Fly ash comes from coal-fired power plants. Its emission will not only generate dust and pollute the atmosphere, but also cause the spread of heavy metal elements if discharged into water bodies, which will seriously endanger human survival and health. At the same time, fly ash itself has a large surface area and porosity, and has good adsorption activity. If fly ash is modified and prepared into a polar molecular adsorbent, it can realize the resource utilization and high value utilization of fly ash. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a preparation method of a mesoporous adsorbent, a mesoporous adsorbent and applications thereof.

[0006] The first object of the present invention is to provide a method for preparing a mesoporous adsorbent. The method uses pretreated fly ash as an adsorption carrier, which is modified with potassium permanganate and then contacted with organic sulfur and nitrogen substances to react. The prepared mesoporous adsorbent can improve the adsorption capacity and desorption efficiency of organic VOCs.

[0007] The second object of the present invention is to provide a mesoporous adsorbent having the characteristics of a large number of mesopores, a large specific surface area, good hydrophobicity, a strong adsorption capacity and easy desorption.

[0008] The third object of the present invention is to provide an application of a mesoporous adsorbent in the field of volatile organic waste gas treatment. The application method is simple and easy, the treatment efficiency is high, and the volatile organic matter can be efficiently treated without generating secondary pollution. At the same time, the desorption efficiency is high, and the adsorbent can be reused.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0010] A method for preparing a mesoporous adsorbent comprises the following steps:

[0011] 1) After pretreatment, the fly ash is modified by adding potassium permanganate solution at room temperature and under ultrasonic wave, and then taken out, dried, and vacuum calcined to obtain potassium permanganate modified fly ash;

[0012] 2) adding the fly ash modified by potassium permanganate into the organic sulfur and nitrogen solution, stirring, filtering, vacuum drying, and calcining to obtain the mesoporous adsorbent.

[0013] The fly ash described in the present invention is the fly ash collected from the flue gas after coal combustion, which mainly comes from power plants. Fly ash has a large specific surface area and a loose porous structure, high content of Al2O3 and SiO2, and good adsorption performance, so it is selected as the adsorbent carrier in the present invention for use.

[0014] Further, the method for pretreating fly ash in step 1) is:

[0015] The fly ash is ground into fine powder, passed through a 80-200 mesh sieve, and then washed and dried; the fly ash is dispersed in water, and polyethylene glycol and bentonite are added, mixed evenly, and then extruded and calcined to obtain pretreated fly ash; the fly ash is modified with polyethylene glycol, which can effectively increase the pore size of the fly ash carrier and improve the proportion of mesopore volume. At the same time, the macropores can reduce the difficulty of desorption of the adsorbent, which is conducive to the realization of vacuum desorption process at room temperature.

[0016] Preferably, the mass ratio of the polyethylene glycol, bentonite and fly ash is (0.01-0.05):(0.6-0.8):1; the amount of water used is 60-80% of the total mass of the polyethylene glycol, bentonite and fly ash.

[0017] Furthermore, before obtaining the pretreated fly ash, it undergoes two calcination processes, which are: calcining at 250-400°C for 3-5 hours in an oxygen-rich atmosphere to remove polyethylene glycol; then, calcining at 500-600°C for 3-5 hours in a nitrogen atmosphere to obtain the pretreated fly ash.

[0018] Furthermore, the concentration of the potassium permanganate solution is 1-10%, preferably 2-8%; the amount of the potassium permanganate solution is (2-3):1 according to the mass ratio of the potassium permanganate solution to the pretreated fly ash. After the fly ash is modified with potassium permanganate, the amount of acidic oxygen-containing functional groups on the surface of the fly ash can be effectively increased, and the adsorption capacity of the fly ash for volatile organic compounds can be enhanced. The accompanying ultrasonic treatment can disperse the effect of potassium permanganate, and the ultrasonic treatment can effectively expand the pore structure of the fly ash, effectively remove impurities on the surface of the fly ash, improve the specific surface area of ​​the fly ash, and strengthen the adsorption effect.

[0019] Furthermore, in step 1), the ultrasonic modification conditions are as follows: the ultrasonic frequency is 80 to 120 Hz, and the ultrasonic treatment time is 2 to 3 hours.

[0020] Furthermore, the vacuum calcination conditions in step 1) are: calcination at a temperature of 450-800°C, preferably 500-600°C for 3-5h under vacuum conditions, and a heating rate of <5°C / min. Vacuum calcination can effectively remove impurities in the adsorbent and increase the specific surface area of ​​fly ash.

[0021] Furthermore, the organic sulfur-nitrogen solution is one or both of 2-thiazolamine and thiocyanate solution, preferably 2-thiazolamine;

[0022] In addition to Al2O3 and SiO2, fly ash also contains a variety of metal elements such as Fe, Ca, Mg, etc. [see Guo Baozhu et al., Determination of 13 elements in fly ash by ICP-AES. Liaoning Chemical Industry, 2002.09, 29-5]. These metal elements can coordinate with nitrogen and sulfur elements. The nitrogen coordination can enhance the binding capacity of nitrogen-containing, oxygen-containing and other polar organic substances, thereby enhancing the adsorbent's adsorption capacity for polar substances such as organic ketones, organic alcohols and organic ethers. In addition, the synergistic effect of sulfur doping reduces the energy barrier for VOCs desorption, thereby improving the desorption efficiency at room temperature and vacuum.

[0023] Preferably, the amount of the organic sulfur-nitrogen solution used is (0.01-0.04):1 based on the mass ratio of nitrogen element to potassium permanganate-modified fly ash, and the solution concentration can be 5-20%.

[0024] Furthermore, in step 2), the stirring treatment conditions of the potassium permanganate-modified fly ash and the organic sulfur and nitrogen solution are as follows: the stirring temperature is 50 to 90° C., preferably 70 to 80° C., and the stirring time is 10 to 50 min, preferably 20 to 30 min;

[0025] Preferably, in step 2), the calcination atmosphere is nitrogen, helium or argon, preferably nitrogen, the calcination temperature is 450-800° C., preferably 500-600° C., the calcination time is 3-5 h, and the heating rate is <5° C. / min.

[0026] In some examples of the present invention, the normal drying condition is drying at 100-120° C. for 2-5 hours, and the vacuum drying condition is vacuum drying at 180-240° C. for 2-5 hours.

[0027] The present invention also provides a mesoporous adsorbent prepared according to the method described above.

[0028] The present invention also provides an application of the mesoporous adsorbent prepared according to the method described above, which is mainly used in the field of volatile organic waste gas treatment;

[0029] Preferably, the volatile organic waste gas contains single-component organic matter or multi-component organic matter, and the volatile organic matter is required to be not easy to polymerize at room temperature. The adsorbent bed is used in one and reserved in another. The waste gas is discharged after being treated by the adsorbent bed at room temperature and pressure. After the adsorbent is saturated with adsorption, the adsorbent bed is vacuum desorbed at a vacuum pressure of 1 to 15 kPa, preferably 2 to 10 kPa. The desorbed gas is recovered after condensation treatment at a condensation temperature of 0 to 20°C, preferably 5 to 15°C.

[0030] The positive effects of the present invention are:

[0031] 1) After the fly ash is modified with polyethylene glycol, the mesoporous pore volume of the fly ash carrier can be effectively increased, and the macropores are conducive to the removal of organic molecules from the pores;

[0032] 2) After the fly ash is modified by potassium permanganate, the amount and specific surface area of ​​the acidic oxygen-containing functional groups on the surface of the fly ash can be effectively increased, and the adsorption capacity of the fly ash for volatile organic compounds can be enhanced;

[0033] 3) The modification of fly ash by organic sulfur and nitrogen substances can improve the adsorption capacity of the adsorbent for polar molecules. At the same time, the synergistic effect of sulfur doping reduces the energy barrier for VOCs desorption, thereby improving the desorption efficiency at room temperature and vacuum;

[0034] 4) The present invention has a simple process for treating volatile organic waste gas, a mild reaction temperature, low energy consumption, and stable performance during long-term operation. DETAILED DESCRIPTION

[0035] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0036] In the following specific implementation of the present invention:

[0037] The adsorbent is loaded into the adsorption tower for use. The adsorption tower is purchased from Yantai Huada Medical Equipment Co., Ltd.;

[0038] Fly ash, from Huaneng Yantai Bajiao Thermal Power Co., Ltd.;

[0039] Volatile organic waste gas, taking artificially prepared acetone waste gas as an example for research;

[0040] The vacuum system uses the SC920G model produced by IKM;

[0041] The specific surface area was measured by a V-Sorb 2800S specific surface area meter produced by Beijing Jin'ep Technology Co., Ltd.

[0042] The acetone concentration was analyzed by gas chromatography external standard method, and the gas chromatograph was Agilent 7890B produced by Agilent.

[0043] [Example 1]

[0044] (1) Grind the collected fly ash into fine powder, pass through an 80-mesh sieve, wash and dry, take 200g of fly ash fine powder, add 120g of bentonite, 10g of polyethylene glycol and 231g of distilled water, mix well and extrude into shape. First calcine at 400℃ in an oxygen-rich atmosphere for 5h, then roast at 500℃ in a nitrogen atmosphere for 3h to obtain pretreated fly ash;

[0045] (2) Take 200 g of pretreated fly ash, add 400 g of 8 wt % potassium permanganate solution, ultrasonicate under 120 Hz ultrasonic condition for 2 h, then take out and dry at 100 ° C for 4 h and then calcine in vacuum at a calcination temperature of 500 ° C, a calcination time of 3 h, and a heating rate of 4 ° C / min to obtain potassium permanganate modified fly ash;

[0046] (3) Prepare a 10 wt% 2-thiazole solution, add 143.1 g of the 2-thiazole solution to 200 g of potassium permanganate modified fly ash, stir at 70 ° C for 30 min, then take out and vacuum dry at 180 ° C for 4 h, and then calcine in a nitrogen atmosphere at a calcination temperature of 500 ° C, a calcination time of 3 h, and a heating rate of 4 ° C / min to finally obtain a mesoporous adsorbent, which is recorded as adsorbent 1#.

[0047] [Example 2]

[0048] (1) Grind the collected fly ash into fine powder, pass it through a 160-mesh sieve, wash it with water and dry it, take 200 g of fly ash fine powder, add 160 g of bentonite, 8 g of polyethylene glycol and 220.8 g of distilled water, mix them evenly and extrude them, first calcine them at 350° C. in an oxygen-rich atmosphere for 4 h, and then roast them at 550° C. in a nitrogen atmosphere for 4 h to obtain pretreated fly ash;

[0049] (2) Take 200 g of pretreated fly ash, add 440 g of 6 wt% potassium permanganate solution, ultrasonicate under 100 Hz ultrasonic condition for 2.5 h, then take out and dry at 105 ° C for 4.5 h and then calcine in vacuum at a calcination temperature of 550 ° C, a calcination time of 4 h, and a heating rate of 5 ° C / min to obtain potassium permanganate modified fly ash;

[0050] (3) Prepare a 10 wt% 2-thiazole solution, add 214.6 g of the 2-thiazole solution to 200 g of potassium permanganate modified fly ash, stir at 72 ° C for 28 min, then take out and vacuum dry at 200 ° C for 4.5 h, and then calcine in a nitrogen atmosphere at a calcination temperature of 550 ° C, a calcination time of 5 h, and a heating rate of 5 ° C / min to finally obtain a mesoporous adsorbent, which is recorded as adsorbent 2#.

[0051] [Example 3]

[0052] (1) Grind the collected fly ash into fine powder, pass it through a 200-mesh sieve, wash it with water and dry it, take 200 g of fly ash fine powder, add 140 g of bentonite, 6 g of polyethylene glycol and 276.8 g of distilled water, mix them evenly and extrude them, first calcine them at 320° C. in an oxygen-rich atmosphere for 3 h, and then calcine them at 600° C. in a nitrogen atmosphere for 5 h to obtain pretreated fly ash;

[0053] (2) Take 200 g of pretreated fly ash, add 520 g of 4 wt% potassium permanganate solution, ultrasonicate under 80 Hz ultrasonic conditions for 3 h, then take it out and dry it at 110° C. for 5 h, and then vacuum calcine it at a calcination temperature of 600° C., a calcination time of 5 h, and a heating rate of 5° C. / min to obtain potassium permanganate modified fly ash;

[0054] (3) Prepare a 10 wt% 2-thiazole solution, add 286 g of the 2-thiazole solution to 200 g of potassium permanganate modified fly ash, stir at 76 ° C for 25 min, then take out and vacuum dry at 220 ° C for 5 h, and then calcine in a nitrogen atmosphere at a calcination temperature of 600 ° C, a calcination time of 4 h, and a heating rate of 5 ° C / min to finally obtain a mesoporous adsorbent, which is recorded as adsorbent 3#.

[0055] [Example 4]

[0056] (1) Grind the collected fly ash into fine powder, pass it through a 140-mesh sieve, wash it with water and dry it, take 200 g of fly ash fine powder, add 160 g of bentonite, 4 g of polyethylene glycol and 254.8 g of distilled water, mix them evenly and extrude them, first calcine them at 300° C. in an oxygen-rich atmosphere for 4 h, and then roast them at 500° C. in a nitrogen atmosphere for 4 h to obtain pretreated fly ash;

[0057] (2) Take 200 g of pretreated fly ash, add 600 g of 2 wt% potassium permanganate solution, ultrasonicate under 90 Hz ultrasonic conditions for 2.5 h, then take it out and dry it at 115 ° C for 4.5 h and then calcine it in vacuum at a calcination temperature of 500 ° C, a calcination time of 4 h, and a heating rate of 5 ° C / min to obtain potassium permanganate modified fly ash;

[0058] (3) Prepare a 10 wt% 2-thiazole solution, add 72 g of the 2-thiazole solution to 200 g of potassium permanganate modified fly ash, stir at 80 ° C for 20 min, then take out and vacuum dry at 240 ° C for 4.5 h, and then calcine in a nitrogen atmosphere at a calcination temperature of 550 ° C, a calcination time of 3 h, and a heating rate of 5 ° C / min to finally obtain a mesoporous adsorbent, which is recorded as adsorbent 4#.

[0059] [Example 5]

[0060] (1) Grind the collected fly ash into fine powder, pass it through a 100-mesh sieve, wash it with water and dry it, take 200 g of fly ash fine powder, add 120 g of bentonite, 2 g of polyethylene glycol and 193.2 g of distilled water, mix them evenly and extrude them into a mold, first calcine them at 250° C. in an oxygen-rich atmosphere for 5 h, and then roast them at 550° C. in a nitrogen atmosphere for 3 h to obtain pretreated fly ash;

[0061] (2) Take 200g of pretreated fly ash, add 540g of 4.5wt% potassium permanganate solution, ultrasonicate for 3h under 110Hz ultrasonic condition, then take out and dry at 120℃ for 4h and then calcine in vacuum at 550℃ for 3h and heating rate of 4℃ / min to obtain potassium permanganate modified fly ash;

[0062] (3) Prepare a 10 wt% 2-thiazole solution, add 250.4 g of the 2-thiazole solution to 200 g of potassium permanganate modified fly ash, stir at 74 ° C for 24 min, then take out and vacuum dry at 210 ° C for 4 h, and then calcine in a nitrogen atmosphere at a calcination temperature of 500 ° C, a calcination time of 5 h, and a heating rate of 4 ° C / min to finally obtain a mesoporous adsorbent, which is recorded as adsorbent 5#.

[0063] [Comparative Example 1]

[0064] The adsorbent was prepared in a method substantially the same as that in Example 3, except that polyethylene glycol was not used for modification in step (1), and the amount of water was modified accordingly, as follows:

[0065] (1) Grind the collected fly ash into fine powder, pass it through a 200-mesh sieve, wash it with water and dry it, take 200 g of fly ash fine powder, add 140 g of bentonite and 272 g of distilled water, mix them evenly and extrude them, first calcine them at 320° C. in an oxygen-rich atmosphere for 3 h, and then roast them at 600° C. in a nitrogen atmosphere for 5 h to obtain pretreated fly ash;

[0066] (2) Take 200g of pretreated fly ash, add 520g of 4wt% potassium permanganate solution, ultrasonicate under 80Hz ultrasonic condition for 3h, then take out and dry at 110℃ for 5h and then calcine in vacuum, the calcination temperature is 600℃, the calcination time is 5h, the heating rate is 5℃ / min, and potassium permanganate modified fly ash is obtained;

[0067] (3) Prepare a 10 wt% 2-thiazole solution, add 286.4 g of the 2-thiazole solution to 200 g of potassium permanganate modified fly ash, stir at 76 ° C for 25 min, then take out and vacuum dry at 220 ° C for 5 h, and then calcine in a nitrogen atmosphere at a calcination temperature of 600 ° C, a calcination time of 4 h, and a heating rate of 5 ° C / min to finally obtain a mesoporous adsorbent, which is recorded as adsorbent D1#.

[0068] [Comparative Example 2]

[0069] The adsorbent was prepared in a method substantially the same as that in Example 3, except that step (2) was deleted, specifically:

[0070] (1) Grind the collected fly ash into fine powder, pass it through a 200-mesh sieve, wash it with water and dry it, take 200 g of fly ash fine powder, add 140 g of bentonite, 6 g of polyethylene glycol and 276.8 g of distilled water, mix them evenly and extrude them, first calcine them at 320° C. in an oxygen-rich atmosphere for 3 h, and then calcine them at 600° C. in a nitrogen atmosphere for 5 h to obtain pretreated fly ash;

[0071] (2) Prepare a 10 wt% 2-thiazole solution, add 286 g of the 2-thiazole solution to 200 g of pretreated fly ash, stir at 76 ° C for 25 min, then take out and vacuum dry at 220 ° C for 5 h, and then calcine in a nitrogen atmosphere at a calcination temperature of 600 ° C, a calcination time of 4 h, and a heating rate of 5 ° C / min to finally obtain a mesoporous adsorbent, which is recorded as adsorbent D2#.

[0072] [Comparative Example 3]

[0073] The adsorbent was prepared in a method substantially the same as that in Example 3, except that step (3) was deleted and the potassium permanganate-modified fly ash prepared in step (2) was directly used as the mesoporous adsorbent, specifically:

[0074] (1) Grind the collected fly ash into fine powder, pass it through a 200-mesh sieve, wash it with water and dry it, take 200 g of fly ash fine powder, add 140 g of bentonite, 6 g of polyethylene glycol and 276.8 g of distilled water, mix them evenly and extrude them, first calcine them at 320° C. in an oxygen-rich atmosphere for 3 h, and then calcine them at 600° C. in a nitrogen atmosphere for 5 h to obtain pretreated fly ash;

[0075] (2) Take 200 g of pretreated fly ash, add 520 g of 4 wt% potassium permanganate solution, and ultrasonicate for 3 h under 80 Hz ultrasonic conditions. Then take it out and dry it at 110°C for 5 h and then calcine it in vacuum at a calcination temperature of 600°C, a calcination time of 5 h, and a heating rate of 5°C / min to obtain potassium permanganate-modified fly ash as a mesoporous adsorbent, which is recorded as adsorbent D3#.

[0076] [Comparative Example 4]

[0077] The adsorbent was prepared in a method substantially the same as that in Example 3, except that the 2-thiazole in step (3) was replaced by pyridine having the same nitrogen content, as follows:

[0078] (1) Grind the collected fly ash into fine powder, pass it through a 200-mesh sieve, wash it with water and dry it, take 200 g of fly ash fine powder, add 140 g of bentonite, 6 g of polyethylene glycol and 276.8 g of distilled water, mix them evenly and extrude them, first calcine them at 320° C. in an oxygen-rich atmosphere for 3 h, and then calcine them at 600° C. in a nitrogen atmosphere for 5 h to obtain pretreated fly ash;

[0079] (2) Take 200 g of pretreated fly ash, add 520 g of 4 wt% potassium permanganate solution, ultrasonicate under 80 Hz ultrasonic conditions for 3 h, then take it out and dry it at 110° C. for 5 h, and then vacuum calcine it at a calcination temperature of 600° C., a calcination time of 5 h, and a heating rate of 5° C. / min to obtain potassium permanganate modified fly ash;

[0080] (3) Prepare a 10 wt% pyridine solution, add 452 g of pyridine solution to 200 g of potassium permanganate modified fly ash, stir at 76 ° C for 25 min, then take out and vacuum dry at 220 ° C for 5 h, and then calcine in a nitrogen atmosphere at a calcination temperature of 600 ° C, a calcination time of 4 h, and a heating rate of 5 ° C / min to finally obtain a mesoporous adsorbent, which is recorded as adsorbent D4#.

[0081]

Application Example 1

[0082] This application example uses the following experimental conditions to evaluate the performance of each adsorbent prepared in the above embodiments and comparative examples:

[0083] Before the experiment, the specific surface area, average pore size, pore volume and mechanical strength of each catalyst were measured (as shown in Table 1), and then the adsorption effect of acetone waste gas was tested. Specifically, an artificial mixture containing 10000 mg / m 3 The air containing acetone is used as acetone waste gas; adsorbent is placed in the adsorption tower (each adsorbent is loaded with 100g), and then the acetone waste gas is passed into the adsorption tower, the waste gas flow rate is 1.5L / min, the bed temperature is kept at 40℃, and the acetone concentration at the outlet is continuously tested. When the concentration exceeds 50mg / m 3 Stop the experiment and record the adsorption effect of the adsorbent as shown in Table 1.

[0084] Table 1. Adsorption effect of adsorbents

[0085]

[0086] From the above test results, it can be seen that the adsorbent prepared by each embodiment of the present invention not only has the advantages of large specific surface area, large average pore size, high porosity and high mechanical strength, but also has good adsorption effect on VOCs in acetone waste gas and good practicality. In addition, by comparing the test results of catalyst 3# and D1#, it can be seen that the average pore size and pore volume of the adsorbent modified by polyethylene glycol are significantly improved, which can show advantages in the desorption performance in Application Example 2.

[0087] From the test results of comparing catalysts 3# and D2#, it can be seen that potassium permanganate modification can effectively increase the specific surface area of ​​the adsorbent and the number of oxygen-containing functional groups on the surface, thereby increasing the adsorption capacity of the adsorbent for organic molecules.

[0088] From the test results of comparing catalysts 3# and D3#, it can be seen that the specific surface area and other properties of the adsorbent without 2-thiazole modification have no obvious changes, but the adsorption performance is significantly reduced, and the adsorption capacity is even lower than that of D2# with low specific surface area. It is inferred that the nitrogen coordination modification improves the adsorption capacity of the adsorbent for polar molecules.

[0089] From the test results of comparing catalysts 3# and D4#, it can be seen that the specific surface area and adsorption performance of the adsorbent prepared with pyridine as the modifier have no obvious changes. The desorption performance is further tested through Application Example 2.

[0090]

Application Example 2

[0091] Catalyst 3#, D1# and D4# were used for adsorption and desorption test evaluation and comparison. The experimental conditions are as follows:

[0092] Artificially formulated to contain 10000mg / m 3The air containing acetone is used as acetone waste gas; adsorbent is placed in the adsorption tower (each adsorbent is loaded with 100g), and then the acetone waste gas is passed into the adsorption tower, the waste gas flow rate is 1.5L / min, the bed temperature is kept at 40℃, and the acetone concentration at the outlet is continuously tested. When the concentration exceeds 50mg / m 3 The adsorption was stopped, and then vacuum desorption was performed on the adsorbent at room temperature. The vacuum was evacuated to 5 kPa, and the desorption time was 1 h. After the desorption, an adsorption experiment was performed. The adsorption-desorption was performed three times each, and the desorption efficiency and adsorption capacity were recorded each time. The results are shown in Table 2:

[0093] Table 2. Evaluation results of adsorption-desorption effect of adsorbents

[0094]

[0095] Comparing the test results of catalyst 3# and D1#, it can be seen that the adsorbent that has not been modified with polyethylene glycol is not completely desorbed each time, resulting in a gradual decrease in adsorption performance. Comparing the test results of catalyst 3# and D4#, it can be seen that the adsorbent that has only been modified by nitrogen coordination without sulfur doping has better adsorption performance, but due to insufficient desorption time each time, some organic matter cannot be quickly desorbed from the pores, and the adsorption capacity slowly decreases.

[0096] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a mesoporous adsorbent, characterized in that: The following steps are involved: 1) After pretreatment, the fly ash is modified by adding potassium permanganate solution at room temperature and under ultrasonic wave, and then taken out, dried and calcined in vacuum to obtain potassium permanganate modified fly ash; 2) adding potassium permanganate modified fly ash to an organic sulfur and nitrogen solution, stirring, filtering, vacuum drying, and calcining to obtain the mesoporous adsorbent; the organic sulfur and nitrogen solution is one or both of 2-thiazolamine and trithiocyanate solution; The method for pre-treating fly ash in step 1) is: The fly ash is ground into fine powder, passed through a 80-200 mesh sieve, and then washed and dried; the fly ash is dispersed in water, and polyethylene glycol and bentonite are added, mixed evenly, and then extruded and calcined to obtain pretreated fly ash.

2. The method for preparing a mesoporous adsorbent according to claim 1, characterized in that: The mass ratio of the polyethylene glycol, bentonite and fly ash is (0.01-0.05):(0.6-0.8):1; the amount of water used is 60-80% of the total mass of the polyethylene glycol, bentonite and fly ash.

3. The method for preparing a mesoporous adsorbent according to claim 2, characterized in that: Before obtaining the pretreated fly ash, the fly ash is subjected to two calcination processes, which are: calcining at 250-400°C for 3-5 hours in an oxygen-rich atmosphere to remove polyethylene glycol; then, calcining at 500-600°C for 3-5 hours in a nitrogen atmosphere to obtain the pretreated fly ash.

4. The method for preparing a mesoporous adsorbent according to any one of claims 1 to 3, characterized in that: The concentration of the potassium permanganate solution is 1-10%; the amount of the potassium permanganate solution used is calculated based on the mass ratio of the potassium permanganate solution to the pretreated fly ash, which is (2-3):

1.

5. The method for preparing a mesoporous adsorbent according to claim 4, characterized in that: The concentration of the potassium permanganate solution is 2-8%.

6. The method for preparing a mesoporous adsorbent according to claim 4, characterized in that: In step 1), the ultrasonic modification conditions are as follows: the ultrasonic frequency is 80 to 120 Hz, and the ultrasonic treatment time is 2 to 3 hours.

7. The method for preparing a mesoporous adsorbent according to claim 6, characterized in that: In step 1), the vacuum calcination conditions are: under vacuum conditions, the temperature is 450-800° C., the calcination time is 3-5 hours, and the heating rate is less than 5° C. / min.

8. The method for preparing a mesoporous adsorbent according to claim 7, characterized in that: The vacuum calcination conditions in step 1) are: under vacuum conditions, the temperature is 500-600°C.

9. The method for preparing a mesoporous adsorbent according to any one of claims 1 to 3, characterized in that: The organic sulfur and nitrogen solution is a 2-thiazolamine solution.

10. The method for preparing a mesoporous adsorbent according to claim 9, characterized in that: The dosage of the organic sulfur-nitrogen solution is calculated based on the mass ratio of nitrogen element to potassium permanganate-modified fly ash, which is (0.01-0.04):

1.

11. The method for preparing a mesoporous adsorbent according to claim 9, characterized in that: In step 2), the stirring conditions of the potassium permanganate modified fly ash and the organic sulfur and nitrogen solution are: the stirring temperature is 50 to 90° C. and the stirring time is 10 to 50 minutes.

12. The method for preparing a mesoporous adsorbent according to claim 11, characterized in that: In step 2), the stirring conditions of the potassium permanganate modified fly ash and the organic sulfur and nitrogen solution are: the stirring temperature is 70-80° C. and the stirring time is 20-30 min.

13. The method for preparing a mesoporous adsorbent according to claim 11, characterized in that: In step 2), the calcination atmosphere is nitrogen, helium or argon, the calcination temperature is 450-800° C., the calcination time is 3-5 hours, and the heating rate is <5° C. / min.

14. The method for preparing a mesoporous adsorbent according to claim 13, characterized in that: The calcination atmosphere in step 2) is nitrogen.

15. The method for preparing a mesoporous adsorbent according to claim 13, characterized in that: In step 2), the calcination temperature is 500-600°C, the calcination time is 3-5h, and the heating rate is <5°C / min.

16. A mesoporous adsorbent prepared according to the method according to any one of claims 1 to 15.

17. Use of a mesoporous adsorbent prepared by the method according to any one of claims 1 to 15, characterized in that: Applied in the field of volatile organic compound waste gas treatment.

18. The use according to claim 17, characterized in that The volatile organic waste gas contains single-component organic matter or multi-component organic matter, and the volatile organic matter is required to be not easy to polymerize at room temperature. The adsorbent bed is used in one and reserved in another. The waste gas is discharged after being treated by the adsorbent bed at room temperature and pressure. After the adsorbent is saturated with adsorption, the adsorbent bed is vacuum desorbed at a vacuum pressure of 1 to 15 kPa. The desorbed gas is recovered after condensation treatment at a condensation temperature of 0 to 20°C.

19. The use according to claim 18, characterized in that The vacuum pressure is 2~10kPa.

20. The use according to claim 18, characterized in that Condensation temperature 5~15℃.

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