AU2021104856A4

AU2021104856A4 - Method and device for removing sulfur dioxide from exhaust gas by adsorption regeneration

Info

Publication number: AU2021104856A4
Application number: AU2021104856A
Authority: AU
Inventors: Bin Li; Ping NING; Wenmin QIAN; Zhizhi Xu
Original assignee: Univ Kunming Science & Technology; Yunnan Res Academy Of Eco Environmental Sciences; Kunming University of Science and Technology
Current assignee: Yunnan Research Academy Of Eco Environmental Sciences; Kunming University of Science and Technology
Priority date: 2021-08-03
Filing date: 2021-08-03
Publication date: 2021-10-14
Anticipated expiration: 2029-08-03

Abstract

OF THE DISCLOSURE The present disclosure relates to the technical field of the desulfurization from exhaust gas, and provides a method and device for removing sulfur dioxide from exhaust gas. Sulfur dioxide is adsorbed from exhaust gas with mesoporous alumina; the adsorbed alumina is regenerated and desorbed with microwave irradiation; and the sulfur dioxide is adsorbed again with the regenerated alumina. The provided method shows high desulfurization rate and greatly reduces the discharge of the sulfur dioxide of the exhaust gas. In addition, the waste mesoporous alumina produced by the present disclosure can be used as a raw material in an electrolytic aluminum electrolysis system; no secondary solid waste is produced; moreover, high-concentration sulfur dioxide can be collected in the regeneration process for further application. The present disclosure has good environmental benefits and economic benefits, and has a very wide social value and prospect. The various treatment units of the provided device are configured reasonably, operated stably and capable of realizing continuous production. ABSTRACT DRAWING - FIG 1 17933739_1 (GHMatters) P116904.AU -1/2 12 51 23 31 11 32 43 21 2 4 5 41 44 2242 FIGI 17933723_1 (GHMaters) P116904.AU

Description

-1/2

12 51 23 31

11 32 43 21 2 4 5 41 44

2242

FIGI

17933723_1 (GHMaters) P116904.AU

METHOD AND DEVICE FOR REMOVING SULFUR DIOXIDE FROM EXHAUST GAS BY ADSORPTION REGENERATION TECHNICAL FIELD

[01] The present disclosure relates to the technical field of exhaust gas desulfurization, specifically relates to a method and device for removing sulfur dioxide from exhaust gas by adsorption and regeneration.

BACKGROUNDART

[02] Sulfur dioxide is one of main pollutants in the atmosphere, and is extremely harmful to animals, plants, buildings and human. For example, sulfur dioxide can be absorbed into the blood, and can destroy the activity of enzyme as well as damage to the liver. Due to the reduction effect of sulfur dioxide, it will cause different degrees of damage to plants, and S02 gas at a high concentration will greatly exceed the stand ability of plants. In a short period of time (1 to 2 days or within a few hours), leaves of plants are withered and fall off, and the growth and development are severely blocked until the plants wither and die. In our country, coal-fired boilers and kilns used in power, chemical and smelting industries emit a large amount of exhaust gas, and the exhaust gas contains a large amount of sulfur dioxide. Therefore, the exhaust gas produced by the industrial coal and kilns must be treated to reach a standard limit before it can be discharged.

[03] An exhaust gas desulfurization technology is the most effective way to control S02 pollution. According to whether there is water participating in the desulfurization process as well as dry and wet states of a desulfurization product, wet exhaust gas desulfurization, semi-dry exhaust gas desulfurization and dry exhaust gas desulfurization can be involved. The simple process of the dry desulfurization technology has attracted wide attention. Common dry desulfurizers include molecular sieves, metal oxides, activated carbon, etc., but they generally have the disadvantage of poor regeneration performance.

SUMMARY

[04] In view of this, the present disclosure is directed to provide a method and device for removing sulfur dioxide from exhaust gas by adsorption and regeneration. The provided method shows the high desulfurization efficiency and the excellent regenerationperformance.

[05] In order to achieve the foregoing invention objective, the present disclosure provides the following technical solution.

[06] The present disclosure provides a method for removing sulfur dioxide from exhaust gas by adsorption and regeneration, including the following steps:

[07] (1) adsorbing sulfur dioxide from exhaust gas with mesoporous alumina to obtain adsorbed alumina;

[08] (2) recycling the adsorbed alumina with microwave irradiation to obtain regenerated alumina;

[09] (3) adsorbing sulfur dioxide from exhaust gas again with the regenerated

17933739_1 (GHMatters) P116904.AU alumina; and

[10] (4) repeating the steps (2) to (3), and replacing new mesoporous alumina when the adsorption capacity of the mesoporous alumina is reduced to 60% or below of the initial capacity.

[11] Preferably, in the step (1), the mesoporous alumina has a particle size of 40 to meshes.

[12] The contact is to make the exhaust gas to pass through the mesoporous alumina. A ratio of the flow velocity of the exhaust gas to the mass of the mesoporous alumina is to 2000 mL/min: 0.1 g. The adsorption temperature is from 30 to 300°C for I to 120 min.

[13] Preferably, in the step (2), the conditions for the microwave irradiation regeneration include: the microwave power of microwave irradiation being 500 to 2500 W, the temperature being 200 to 600°C, and the time being 10 to 120 min.

[14] The present disclosure provides a device for removing sulfur dioxide from exhaust gas by adsorption and regeneration, including an adsorbent warehouse 1, the adsorbent warehouse 1 being provided with an adsorbent inlet 12;

[15] a fixed bed reactor 2 with a feed port 21 communicating with an adsorbent warehouse outlet 1.1, the fixed bed reactor 2 being also provided with an exhaust gas inlet 22 and an exhaust gas outlet 23;

[16] a dust remover 3 with a dust removal inlet 31 communicating with the exhaust gas outlet 23 of the fixed bed reactor 2;

[17] a microwave regeneration system 4 with a regeneration inlet 41 communicating with a dust removal outlet 32 of the dust remover 3. The microwave regeneration system 4 is provided with a waste adsorbent outlet 42, a regenerated adsorbent outlet 43 and a sulfur dioxide outlet 44. The regenerated adsorbent outlet 43 communicates with the adsorbent inlet 12 of the adsorbent warehouse 1.

[18] Preferably, the device further includes a sulfur dioxide reservoir 5 with a storage inlet 51 communicating with the sulfur dioxide outlet 44 of the microwave regeneration system 4.

[19] The waste adsorbent outlet 42 of the microwave regeneration system 4 communicates with an electrolytic aluminum electrolysis system 6.

[20] The present disclosure provides a method for removing sulfur dioxide from exhaust gas by adsorption and regeneration, including the following steps: (1) adsorbing sulfur dioxide from exhaust gas with mesoporous alumina to obtain adsorbed alumina; (2) recycling the adsorbed alumina with microwave irradiation to obtain regenerated alumina; (3) adsorbing sulfur dioxide from exhaust gas again with the regenerated alumina; and (4) repeating the steps (2) to (3), and replacing new mesoporous alumina when the adsorption capacity of the mesoporous alumina is reduced to 60% or below of the initial capacity. The mesoporous alumina used in the present disclosure has high specific surface area (270 m 2 /g) with large pore channels (7.1 nm), and shows high desulfurization rate for removing sulfur dioxide in the exhaust gas, and can greatly cut down the discharge of the sulfur dioxide in the exhaust gas. The mesoporous alumina regenerated by the microwave irradiation has excellent regeneration performance. Further, the waste mesoporous alumina produced by desulfurization can be conveyed

2 17933739_1 (GHMatters) P116904.AU into the electrolytic aluminum electrolysis system and serves as a raw material. Thus, no secondary solid waste is produced, and the problem that a large number of solid wastes are produced in the traditional desulfurization process can be solved. Further, the present disclosure can collect the high concentration of sulfur dioxide in the regeneration process for utilization, which has good environmental and economic benefits, and has an extremely large social value and wide prospect.

[21] The present disclosure further provides a device for removing sulfur dioxide from exhaust gas by adsorption and regeneration. The various treatment units of the device provided by the present disclosure are configured reasonably, stable in operation and capable of realizing continuous production.

BRIEF DESCRIPTION OF THE DRAWINGS

[22] FIG. 1 is a schematic structural diagram of a device for removing sulfur dioxide from exhaust gas by adsorption and regeneration according to the present disclosure. 1: adsorbent warehouse; 11: adsorbent warehouse outlet; 12: adsorbent inlet; 2: fixed bend reaction region; 21: feed port; 22: exhaust gas inlet; 23: exhaust gas outlet; 3: dust remover; 31: dust removal inlet; 32: dust removal outlet; 4: microwave regeneration system; 41: regeneration inlet; 42: waste adsorbent outlet; 43: regenerated adsorbent outlet; 44: sulfur dioxide outlet; 5: sulfur dioxide reservoir; 51: storage inlet; 6: electrolytic aluminum electrolysis system; and 7: electrolytic aluminum discharge exhaust gas system.

[23] FIG. 2 illustrates an N 2 adsorption-desorption isotherm of mesoporous alumina prepared in Embodiment 1.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[24] The present disclosure provides a method for removing sulfur dioxide from exhaust gas by adsorption and regeneration, including the following steps:

[25] (1) adsorbing sulfur dioxide from exhaust gas with mesoporous alumina to obtain adsorbed alumina;

[26] (2) recycling the adsorbed alumina with microwave irradiation to obtain regenerated alumina;

[27] (3) adsorbing sulfur dioxide from exhaust gas again with the regenerated alumina;

[28] (4) repeating the steps (2) to (3), and replacing new mesoporous alumina when the adsorption capacity of the mesoporous alumina is reduced to 60% or below of the initial capacity.

[29] In the present disclosure, unless otherwise specified, all raw material components are commercially known to persons skilled in the art.

[30] In the present disclosure, the sulfur dioxide is adsorbed from the exhaust gas with the mesoporous alumina to obtain the adsorbed alumina.

[31] The present disclosure has no special limitation to the source of the exhaust gas as long as the exhaust gas contains sulfur dioxide. In the embodiment of the present disclosure, the exhaust gas preferably uses simulated exhaust gas that preferably includes sulfur dioxide, air, etc.; and the concentration of the sulfur dioxide in the

3 17933739_1 (GHMatters) P116904.AU simulated exhaust gas is 50 to 2000 ppm, preferably 500 ppm. In the present disclosure, preferably, the exhaust gas flows through the mesoporous alumina.

[32] In the present disclosure, the mesoporous alumina has a particle size of 20 to 200 meshes, more preferably 40 to 60 meshes.

[33] In the present disclosure, the mesoporous alumina is preferably obtained by the following steps: Pluronic P123, concentrated nitric acid, aluminum isopropoxide and an alcohol solvent were mixed completely, and the obtained solutions were crystallized and calcined in sequence to obtain the mesoporous alumina. In the present disclosure, the mass ratio of the Pluronic P123 to the concentrated nitric acid to the aluminum isopropoxide is preferably 0.8-1: 1-3: 2-4, more preferably 0.9: 1.5: 2.5. In the present disclosure, the concentration of hydrochloric acid is preferably 37 wt%, and a ratio of the mass of the aluminum isopropoxide to the volume of the hydrochloric acid is preferably 2-3 g: 1.4-1.6 mL. In the present disclosure, the alcohol solvent preferably includes one or more of ethanol, methanol and glycerol; a ratio of the mass of the aluminum isopropoxide to the volume of an alcohol reagent is preferably 1 g: 5-20 mL, more preferably 1 g:10 mL. In the present disclosure, the mixing method is preferably to dissolve the Pluronic P123 in the alcohol solvent, and then the nitric acid and the aluminum isopropoxide were added and mixed; room temperature is preferred for mixing temperature, and the time of the mixing is preferably 3 to 8 h, more preferably 5 h. In the present disclosure, the temperature of the crystallization is preferably 60 to 100°C, more preferably 70 to 80°C; the time of the crystallization is preferably 40 to 80 h, more preferably 60 to 70 h. The crystallization is preferably carried out in a constant temperature furnace; and the crystallization process forms mesoporous micelles through a self-assembling process. In the present disclosure, the temperature rate rising from the room temperature to the temperature of the calcination is preferably 5 to 20°C/min, more preferably 10 to 15°C/min; the temperature of the calcination is 500 to 800°C, more preferably 600 to 700°C; the time of the calcination is preferably 2 to 8 h, more preferably 4 to 6 h; and the atmosphere of the calcination is preferably air. After the calcination, the present disclosure preferably further includes tableting and molding the calcined alumina, thus obtaining the mesoporous alumina. The present disclosure has no special limitation to the method of tableting, as long as the mesoporous alumina can be tableted and formed to 40 to 60 meshes. The mesoporous alumina prepared by the present disclosure has the characteristics of high specific surface area and large channel, and is favorable for increasing the number of cycles.

[34] In the present disclosure, a ratio of the flow velocity of the exhaust gas to the mass of the mesoporous alumina is preferably 50 to 2000 mL/min: 0.1 g, more preferably 100 to 1500 mL/min: 0.1 g; the temperature of the adsorption is preferably to 300°C, more preferably 50 to 100°C; the time of the adsorption is preferably 1 to 120 min, more preferably 5 to 30min.

[35] After the adsorbed alumina is obtained, the present disclosure recovers the adsorbed alumina and performs microwave irradiation regeneration to obtain the regenerated alumina.

[36] In the present disclosure, the adsorbed alumina is subjected to the microwave irradiation regeneration and desorption and is reused in the removal of the sulfur

4 17933739_1 (GHMatters) P116904.AU dioxide from the exhaust gas. In the present disclosure, the conditions for the microwave irradiation regeneration and desorption preferably include: the microwave power of microwave irradiation is preferably 500 to 2500 W, more preferably 1500 to 2000 W; and the temperature of the microwave irradiation is preferably 200 to 600°C, more preferably 300 to 400 °C. The time for rising temperature from the room temperature to the temperature of the microwave irradiation is preferably 2 to 3min. With respect to the time for rising the temperature to the desired temperature of the microwave irradiation, the time of 10 to 120 min is preferred, more preferably 20 to 60 min. Compared with a temperature field under conventional heating, the temperature field under microwave heating is more synergistic and selective, and its energy can be concentrated on specific absorbing impurities, so as to perform precise regeneration of desulfurization mesoporous alumina. By the adoption of the microwave irradiation regeneration and desorption, the present disclosure can shorten the regeneration and desorption time; the harmful gas adsorbed in the mesoporous alumina can be regenerated and desorbed using the microwave irradiation; the regeneration effect of the mesoporous alumina can be guaranteed to the maximum extent. In the regeneration process, the sulfur dioxide adsorbed in the mesoporous alumina is desorbed. In the present disclosure, the desorbed sulfur dioxide with high-concentration is preferably desorbed. In the specific embodiments of the present disclosure, the recycled high-concentration sulfur dioxide can be used for acid production to realize reutilization and improvement of the economic benefit.

[37] After the regenerated alumina is obtained, the present disclosure makes the regenerated alumina again contact the exhaust gas again for sulfur dioxide adsorption. In the present disclosure, the operating conditions for the second contact with the exhaust gas for the sulfur dioxide adsorption are consistent with the above-mentioned solution, and descriptions thereof are omitted here.

[38] The present disclosure repeats the steps of adsorbent regeneration and sulfur dioxide adsorption, so that when the adsorption capacity of the mesoporous alumina is reduced to 60% or below of the initial capacity, new mesoporous alumina is replaced. In the specific embodiments of the present disclosure, the number of repeated uses of the mesoporous alumina is preferably 1 to 10. The present disclosure preferably feeds the waste mesoporous alumina with the adsorption capacity reduced to 60% or below of the initial capacity into an electrolytic aluminum electrolysis system and is comprehensively used as a raw material to avoid resource waste and production of secondary solid waste.

[39] The present disclosure further provides a device for removing sulfur dioxide from exhaust gas by adsorption and regeneration, including an adsorbent warehouse 1, a fixed bed reactor 2, a dust remover 3, and a microwave regeneration system 4.

[40] The device provided by the present disclosure includes the adsorbent warehouse 1. The adsorbent warehouse 1 is provided with an adsorbent warehouse outlet 11 and an adsorbent inlet 12. In the present disclosure, the adsorbent warehouse 1 is used to store the initial mesoporous alumina and the regenerated mesoporous alumina, and continuously and uniformly add mesoporous alumina to a feed port 21 of the fixed bed reactor.

5 17933739_1 (GHMatters) P116904.AU

[41] The device provided by the present disclosure includes the fixed bed reactor 2. In the present disclosure, the fixed bed reactor 2 is provided with the feed port 21, an exhaust gas inlet 22 and an exhaust gas outlet 23. The feed port 21 communicates the adsorbent warehouse outlet 1.1 of the adsorbent warehouse 1. The exhaust gas inlet 22 preferably communicates with an electrolytic aluminum discharge exhaust gas system 7, and the electrolytic aluminum discharge exhaust gas system 7 is used to provide exhaust gas. The exhaust gas is preferably defluorinated exhaust gas. In the present disclosure, the fixed bed reactor is preferably a reaction tube, and a material of the reaction tube is preferably quartz glass. The fixed bed reactor 2 used in the present disclosure can use a fewer of catalysts and a smaller reaction vessel to achieve higher desulfurization efficiency.

[42] The device provided by the present disclosure includes the dust remover 3. The dust remover 3 is provided with a dust removal inlet 31 and a dust removal outlet 32. In the present disclosure, the dust removal inlet 31 of the dust remover 3 communicates with the exhaust gas outlet 23 of the fixed bed reactor 2. The present disclosure has no special requirements on the specific structure of the dust remover 3. In the specific embodiment of the present disclosure, it is preferable to select the dust remover according to the granular properties of the mesoporous alumina after the sulfur dioxide adsorption, the recycling efficiency of the mesoporous alumina, the performance of the dust remover, and the economic benefits. In the present disclosure, the adsorbed mesoporous alumina is recycled through the dust remover.

[43] The device provided by the present disclosure includes the microwave regeneration system 4. The microwave regeneration system 4 is provided with a regeneration inlet 41, a waste adsorbent outlet 42, a regenerated adsorbent outlet 43, and a sulfur dioxide outlet 44. The regeneration inlet 41 communicates with the dust removal outlet 32 of the dust remover 3. The regenerated adsorbent outlet 43 communicates with the adsorbent inlet 12 of the adsorbent warehouse 1. The waste adsorbent outlet 42 preferably communicates with an electrolytic aluminum electrolysis system 6. The microwave regeneration system is a novel regeneration technology developed on the basis of the thermal regeneration method that uses electricity as an energy source, uses a magnetron to generate microwaves, and uses huge energy brought by irradiation to realize regeneration. The present disclosure does not have special requirements for the microwave regeneration system, but uses a microwave regeneration system that is well known to those skilled in the art.

[44] The device provided by the present disclosure also preferably includes a sulfur dioxide reservoir 5. The sulfur dioxide reservoir 5 is provided with a storage inlet 51. In the present disclosure, the sulfur dioxide reservoir 5 communicates with the sulfur dioxide outlet 44 of the microwave regeneration system 4. In the embodiments of the present disclosure, the sulfur dioxide reservoir 5 is preferably an air bag. In the present disclosure, the sulfur dioxide reservoir is used to temporarily store the regenerated high-concentration sulfur dioxide, which is convenient for subsequent acid production or other uses.

[45] The device provided by the present disclosure can realize continuous production and greatly improve the desulfurization efficiency.

6 17933739_1 (GHMatters) P116904.AU

[46] FIG. 1 is a schematic structural diagram of the device provided by the present disclosure. The specific process of using the device of the present disclosure to remove sulfur dioxide from exhaust gas will be described below with reference to FIG. 1. Mesoporous alumina continuously enters the fixed bed reactor 2 from the adsorbent warehouse 1; exhaust gas enters from the exhaust gas inlet 2.2 of the fixed bed reactor 2 and comes into contact with the mesoporous alumina. The adsorbed exhaust gas and an adsorbent flow out from the exhaust gas outlet 23 of the fixed bed reactor 2 into the dust remover 3. The dust remover collects the adsorbed mesoporous alumina, and the desulfurized exhaust gas meets a standard limit and then is discharged. The collected adsorbent enters the microwave regeneration system 4 for regeneration, and the regenerated adsorbent is returned to the adsorbent warehouse 5 for reuse. The sulfur dioxide desorbed in the regeneration process enters the sulfur dioxide reservoir 5; the adsorbent repeats the process of adsorbing sulfur dioxide and regeneration till the adsorption capacity is reduced to 60% or below, the adsorbent is discharged from the waste adsorbent outlet 42 of the microwave regeneration system 4 and enters the electrolytic aluminum electrolysis system 6.

[47] The technical solutions in the present disclosure will be described clearly and completely below in combination with the accompanying drawings in the embodiments of the present disclosure. It is apparent that the described embodiments are a part of the embodiments of the present disclosure, not all the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those ordinarily skilled in the art without creative work shall fall within the protection scope of the present disclosure.

[48] Embodiment 1

[49] (1) Preparation of mesoporous alumina: 0.8 g of Pluronic P123 was dissolved in mL of ethanol, the solution was added into 1.6 mL of nitric acid with the concentration of 37 wt% and 2.0 g of aluminum isopropoxide for stirring for 5 h, the mixture was crystallized in a constant temperature furnace at 65°C for 75 h, the obtained sample was calcined in air at 550°C for 4 h and then was tableted and molded to 40 to 60 meshes to obtain the mesoporous alumina.

[50] (2) The device in FIG. 1 was used to remove sulfur dioxide from simulated exhaust gas. A specific flow was as follows:

[51] (2.1) the mesoporous alumina was continuously put into the fixed bed reactor 2 from the adsorbent warehouse 1 to adsorb sulfur dioxide from the simulated exhaust gas (the concentration of the sulfur dioxide was measured every 2 to 5 min) to obtain adsorbed alumina, wherein a ratio of the flow velocity of the simulated exhaust gas to the mass of the mesoporous alumina was 200 mL/min: 0.1 g, the temperature of the adsorption was 30°C, and the time of the adsorption was 60 min;

[52] (2.2) the adsorbed exhaust gas and the adsorbed alumina came out from the exhaust gas outlet 23 of the fixed bed reactor 2 into the dust remover 3; the dust remover collected the adsorbed mesoporous alumina; the desulfurized exhaust gas met the standard and then was discharged; the collected adsorbed alumina was regenerated in the microwave regeneration system 4 filled with high-purity nitrogen to obtain the regenerated alumina, wherein the microwave power was1800 W; the room temperature

7 17933739_1 (GHMatters) P116904.AU was maintained for 20 min after rising to 400°C for 2 to 3 min; the desorbed sulfur dioxide in the regeneration process was stored in the sulfur dioxide reservoir 5;

[53] (2.3) the regenerated adsorbent was returned to the adsorbent warehouse 5 and then entered the fixed bed reactor 2 again to adsorb the sulfur dioxide; after the mesoporous alumina was repeatedly used for 5 times, the adsorption capacity was reduced to 90.2% of the initial capacity; and the waste mesoporous alumina was discharged from the waste mesoporous alumina outlet 4.2 of the microwave regeneration system into the electrolytic aluminum electrolysis system 6.

[54] The initial sulfur dioxide content of the exhaust gas, the desulphurization efficiency in the recycling process of the mesoporous alumina, and the regeneration efficiency of the mesoporous alumina are shown in FIG. 2 and Table 1:

Table 1 Desulphurization result of sulfur dioxide from simulated exhaust gas Initial sulfur dioxide Sulfur dioxide Regeneration Number of content of the content in efficiency of the cycles simulated exhaust desulphurized mesoporous gas/200 mL/min exhaust gas/% alumina /%

1 97.6

/ 2 94.6 96.9 3 500 94 96.3 4 92.2 94.5 5 90.2 92.4

[55] The regeneration efficiency of the mesoporous alumina is a ratio of the adsorption rate of the regenerated mesoporous alumina to the initial adsorption rate, and used data is at the 5th min.

[56] It can be known from Table 1 that the mesoporous alumina has high initial adsorption efficiency and good regeneration effect.

[57] The N 2 adsorption-desorption isotherm of the mesoporous alumina is shown in FIG. 2. It can be known from FIG. 2 that the mesoporous alumina is prepared in the present disclosure.

[58] The NOVA 4200e adsorber was used to measure the specific surface area and a porous structure of the mesoporous alumina. Test conditions were listed as followed: 0.1 g of mesoporous alumina was pretreated at 300°C for 3 h under a vacuum condition to remove impurities, high-purity nitrogen was used as an adsorbent, and the specific area and the pore channel were measured at a liquid nitrogen temperature (-196°C). Measurement results: the specific surface area of the mesoporous alumina: 270 m2/g, and the pore channel: 7.1 nm.

[59] Embodiment 2

[60] The sulfur dioxide was removed according to the method of Embodiment 1, and a difference from Embodiment 1 is that the temperature of the adsorption in the step 8 17933739_1(GHMatters) P116904.AU

(2.1) was 100°C.

[611 Embodiment 3

[621 The sulfur dioxide was removed according to the method of Embodiment 1, and a difference from Embodiment 1 is that the temperature of the adsorption in the step (2.1) was 200°C.

[63] Embodiment 4

[64] The sulfur dioxide was removed according to the method of Embodiment 1, and a difference from Embodiment 1 is that the temperature of the adsorption in the step (2.1) was 250°C.

[65] Embodiment 5

[66] The sulfur dioxide was removed according to the method of Embodiment 1, and a difference from Embodiment 1 is that a ratio of the flow velocity of the simulated exhaust gas in the step (2.1) to the mass of the mesoporous alumina was 400 mL/min: 0.1 g.

[67] Embodiment 6

[68] The sulfur dioxide was removed according to the method of Embodiment 1, and a difference from Embodiment 1 is that a ratio of the flow velocity of the simulated exhaust gas in the step (2.1) to the mass of the mesoporous alumina was 800 mL/min: 0.1 g.

[69] Embodiment 7

[70] The sulfur dioxide was removed according to the method of Embodiment 1, and a difference from Embodiment 1 is that a ratio of the flow velocity of the simulated exhaust gas in the step (2.1) to the mass of the mesoporous alumina was 1500 mL/min: 0.1 g.

[71] Embodiment 8

[72] The sulfur dioxide was removed according to the method of Embodiment 1, and a difference from Embodiment 1 is that a ratio of the flow velocity of the simulated exhaust gas in the step (2.1) to the mass of the mesoporous alumina was 2000 mL/min: 0.1 g.

[73] Embodiment 9

[74] The sulfur dioxide was removed according to the method of Embodiment 1, and a difference from Embodiment 1 is that the time of the microwave adsorption in the step (2.1) was 60 min.

[75] Comparative example 1

[76] The sulfur dioxide was removed according to the method of Embodiment 1, and a difference from Embodiment 1 is that the mesoporous alumina is replaced with commercial alumina.

[77] Comparative example 2

[78] The sulfur dioxide was removed according to the method of Embodiment 1, and a difference from Embodiment 1 is that the mesoporous alumina is replaced with potassium-modified mesoporous alumina.

[79] Desulfurization effects when the adsorption in the step (2.1) is carried out for 5 min in Embodiments 1 to 9 and Comparative examples 1 to 2 are shown in Table 2:

9 17933739_1 (GHMatters) P116904.AU

Table 2 Desulphurization result of sulfur dioxide from simulated exhaust gas

Initial sulfur dioxide content

Example of the simulated exhaust Desulphurization rate/%

gas/200 mL/min

Embodiment 1 97.6

Embodiment 2 87.4

Embodiment 3 77.6

Embodiment 4 66

Embodiment 5 89

Embodiment 6 84

Embodiment 7 500 69

Embodiment 8 67

Embodiment 9 94

Comparative 17 example 1

Comparative 85.2 example 2

[80] It can be seen from Table 2 that the removing effect of sulfur dioxide is far better for the mesoporous alumina than that of the commercial alumina, and at the same time, it is also better than the potassium-modified mesoporous alumina; the removing effect of sulfur dioxide over the mesoporous alumina decreases with the increase of temperature; at the same time, the removing effect of sulfur dioxide over the mesoporous alumina decreases with the increase of the gas flow velocity of the sulfur dioxide; and in addition, the time of the microwave radiation regeneration has little impact on the removing effect of sulfur dioxide over the mesoporous alumina.

[81] It can be seen from the above embodiments that the method provided by the present disclosure shows a high desulfurization rate; the waste mesoporous alumina can be used in the electrolytic aluminum electrolysis system; no secondary solid waste is produced; moreover, the high-concentration sulfur dioxide can be collected in the regeneration process for further application. The present disclosure has good environmental benefits and economic benefits, and shows a very wide social value and prospect.

[82] The above describes only the preferred embodiments of the present disclosure. It should be noted that those of ordinary skill in the art can further make several improvements and retouches without departing from the principles of the present

10 17933739_1 (GHMatters) P116904.AU disclosure. These improvements and retouches shall all fall within the protection scope of the present.

[831 It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

[84] In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

11 17933739_1(GHMatters) P116904.AU

Claims

WHAT IS CLAIMED IS:

1. A method for removing sulfur dioxide from exhaust gas by adsorption and regeneration, comprising the following steps: (1) adsorbing sulfur dioxide from exhaust gas with mesoporous alumina to obtain adsorbed alumina; (2) recycling the adsorbed alumina with microwave irradiation to obtain regenerated alumina; (3) adsorbing sulfur dioxide from exhaust gas again with the regenerated alumina; (4) repeating the steps (2) to (3), and replacing new mesoporous alumina when the adsorption capacity of the mesoporous alumina is reduced to 60% or below of the initial capacity.

2. The method according to claim 1, wherein in the step (1), the mesoporous alumina has a particle size of 40 to 60 meshes; the exhaust gas passes through the mesoporous alumina; a ratio of the flow velocity of the exhaust gas to the mass of the mesoporous alumina is 50 to 2000 mL/min: 0.1 g; the adsorption temperature is 30 to 300°C; and the time is I to 120 min.

3. The method according to claim 1, wherein in the step (2), the conditions for the microwave irradiation regeneration comprise: the microwave power of microwave irradiation being 500 to 2500 W, the temperature being 200 to 600°C and the time being to 120 min.

4. A device for removing sulfur dioxide from exhaust gas by adsorption and regeneration, comprising an adsorbent warehouse (1), wherein the adsorbent warehouse (1) is provided with an adsorbent inlet (12); a fixed bed reactor (2) with a feed port (21) communicating with an adsorbent warehouse outlet (11), wherein the fixed bed reactor (2) is also provided with an exhaust gas inlet (22) and an exhaust gas outlet (23); a dust remover (3) with a dust removal inlet (31) communicating with the exhaust gas outlet (23) of the fixed bed reactor (2); a microwave regeneration system (4) with a regeneration inlet (41) communicating with a dust removal outlet (32) of the dust remover (3), wherein the microwave regeneration system (4) is provided with a waste adsorbent outlet (42), a regenerated adsorbent outlet (43) and a sulfur dioxide outlet (44); and the regenerated adsorbent outlet (43) communicates with the adsorbent inlet (12) of the adsorbent warehouse (1).

5. The device according to claim 4, further comprising a sulfur dioxide reservoir (5) with a storage inlet (51) communicating with the sulfur dioxide outlet (44) of the microwave regeneration system (4), wherein the waste adsorbent outlet (42) of the microwave regeneration system (4) communicates with an electrolytic aluminum electrolysis system (6).

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