Method for capturing SO2 through metal organic framework material slurry and application of method

Abstract

The invention discloses a method for capturing SO2 through metal organic framework material slurry and application of the method, and belongs to the technical field of SO2 capturing. The method comprises the following steps: S1, mixing MOF and an organic solvent to form a compounded MOF slurry absorbent; s2, putting the MOF slurry absorbent into a reaction device, introducing SO2 into the reaction device, and absorbing under certain pressure and temperature conditions until the absorption is saturated, so as to obtain saturated slurry; and desorbing the saturated slurry at a certain temperature in a vacuum environment, separating SO2 from the MOF slurry absorbent, and recycling the MOF slurry absorbent to absorb SO2. The method has the advantages of simplicity in slurry preparation, high absorption capacity, easiness in desorption, low loss rate and reusability; the method is simple and easy to implement, and has a wide application prospect in the field of SO2 trapping.

Description

Technical Field

[0001] The present invention relates to the technical field of SO2 capture, and in particular to a method for capturing SO2 with a metal organic framework material slurry and an application thereof. Background Art

[0002] The combustion of fossil energy produces a large amount of flue gas, which contains a large amount of SO2, SO3, HCl, HF, NO x and a small amount of harmful organic matter, causing serious environmental pollution. SO2 is the most common sulfur oxide, a colorless and strongly irritating gas, and one of the important pollutants in the atmosphere. It mainly comes from the combustion process of fossil energy (coal, oil and natural gas), as well as non-ferrous metal smelting, oil processing and production, sulfuric acid plant acid production, pulp and paper industry, etc., among which thermal power plants are the most serious. SO2 released into the environment reacts with H2O(g) to form acid rain. The formation of acid rain will seriously erode houses and bridges, reducing their service life; the acidification of surface water and the destruction of the natural environment will cause the death of animals and plants, seriously threatening their survival. SO2 emitted into the atmosphere also causes serious harm to human health and leads to the occurrence of many diseases.

[0003] At present, there are several mature desulfurization technologies, such as using sodium hydroxide, ammonia washing or using limestone-gypsum as an alkaline absorbent. However, these treatment methods still have some disadvantages, such as inconvenient recovery and reuse, pipeline corrosion or generation of liquid or solid waste, high energy consumption, etc.

[0004] Adsorption has been widely used in gas separation due to its advantages such as low energy consumption, convenience and high speed. A variety of porous materials such as zeolites, mesoporous carbons, porous polymers, covalent organic frameworks (COFs) and metal organic frameworks (MOFs) have been used as adsorbents for capturing SO2 under ambient conditions. Among them, MOFs are generally considered to be the most promising candidates due to their easily adjustable structure, controllable pore size, large surface area, and the presence of unsaturated metal sites.

[0005] For example, the Chinese invention patent with publication number CN112742351A discloses a SO2 adsorption material and its preparation method and application, and a method for removing SO2 from SO2-containing flue gas. The SO2 adsorption material contains a carbonized metal organic framework material and a sulfite loaded on the carbonized metal organic framework material, has a high SO2 adsorption capacity, can be regenerated by heating and desorption, and the adsorption amount remains at a high level after multiple cycles of adsorption-desorption. Similarly, the Chinese invention patent with publication number CN114433026A provides a SO2 adsorption material and its preparation method. The SO2 adsorption material obtained by modifying the MOFs material and loading sodium sulfite and disodium ethylenediaminetetraacetate has a high SO2 adsorption capacity and selectivity.

[0006] However, the adsorption method for capturing sulfur dioxide in industry is a semi-continuous process. After the adsorption tower is saturated with adsorption, it needs to be switched to another adsorption tower for absorption. The saturated adsorption tower needs to be desorbed and then adsorbed again. In addition, the heat of the entire process cannot be integrated, resulting in heat loss.

[0007] The Chinese invention patent with the publication number CN108579378A provides a method for effectively utilizing sulfur dioxide in waste gas, wherein an absorption liquid prepared from tertiary amine organic matter and organic solvent absorbs SO2 in waste gas to obtain a solid absorption product, which is then used in an organic synthesis reaction to synthesize sulfonamide substances. The absorption liquid absorbs SO2 to achieve the effect of liquid-solid phase separation, and the obtained solid phase product has stable properties and can be directly used in organic synthesis reactions to synthesize a variety of high value-added products. It can also achieve the regeneration of the absorbent (tertiary amine) during the reaction process, and the organic solvent in the liquid phase can be recovered and added to the absorbent to absorb SO2 cyclically. However, this process uses a phase-change absorbent and captures SO2 based on chemical absorption, and the overall process energy consumption is high; secondly, phase change will occur during the absorption process, and the captured absorbent needs to be separated from the solid and liquid, and then regenerated. The process is complicated and requires the addition of absorbent, and the continuity also needs to be optimized.

[0008] In summary, providing a process for capturing SO2 that overcomes the defects of the existing methods such as complex steps, lack of continuity, high energy consumption, and inability to achieve heat integration is of great significance to the field of SO2 capture technology. Summary of the invention

[0009] In view of the above-mentioned defects of the prior art, in the first aspect of the present invention, a method for capturing SO2 using a metal organic framework material slurry is provided, which has the advantages of simple process, continuous operation, high absorption capacity, easy desorption, good stability, recyclability and low loss rate, and comprises the following steps: S1. Mixing MOF and an organic solvent to form a composite MOF slurry absorbent; S2. Place the MOF slurry absorbent in a reaction device, introduce SO2 into the reaction device, and absorb it under certain pressure and temperature conditions until the absorption is saturated to obtain a saturated slurry; then desorb the saturated slurry under a certain temperature and vacuum environment to separate SO2 and the MOF slurry absorbent, and recycle the MOF slurry absorbent to absorb SO2.

[0010] Preferably, in S1, MOF includes one of ZIF-8, ZIF-67, CAF-20, DTU-67, and MOF-74.

[0011] Preferably, in S1, the organic solvent includes one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and polyethylene glycol dimethyl ether.

[0012] The present invention preferably uses the above-mentioned type of macromolecular solvent to overcome the pore blockage caused by the MOF pore structure being filled with liquid. In addition, there is no loss of solvent during the entire absorption process, and the selected macromolecular solvent has a low vapor pressure and low volatility, which is conducive to reducing the loss rate and ensuring the continuous operation of SO2 capture.

[0013] Preferably, in S1, the mass fraction of MOF in the MOF slurry absorbent is 5 wt.%-20 wt.%.

[0014] Preferably, in S2, the absorption temperature is 20-50°C, and the absorption pressure is 0-20 kPa.

[0015] Preferably, in S2, the absorption time is 1-5 min.

[0016] Preferably, in S2, when the pressure in the reaction device remains unchanged, it is considered to have reached a state of absorption saturation.

[0017] Preferably, in S2, the desorption temperature is 60-90°C.

[0018] In the process of SO2 capture, the lower the regeneration temperature of desorption, the lower the energy consumption; the higher the regeneration temperature, the more thorough the desorption. Within the preferred range of the present invention, both the energy consumption reduction and the desorption requirements can be taken into account.

[0019] Preferably, in S2, when recycled and reused, the saturated slurry is transported to a desorption device and desorbed under a certain temperature and vacuum environment; wherein, the saturated slurry is transported from the reaction device to a heat exchange device and heat exchanged with the MOF slurry absorbent separated by the desorption device; the saturated slurry after heat exchange is transported to the desorption device for desorption, and the MOF slurry absorbent after heat exchange re-enters the reaction device to capture SO2.

[0020] In the actual industrial continuous capture of SO2 process, heat integration is mainly achieved by heat exchange between the reaction device (such as absorption tower, reactor, etc.) and the desorption device (such as desorption tower) through a heat exchange device (such as a heat exchanger). Specifically, the MOF slurry absorbent in the absorption tower enters the absorption tower from the top of the tower to absorb SO2, and the absorbed saturated slurry enters the heat exchanger to exchange heat with the MOF slurry absorbent coming out of the bottom of the desorption tower, and then re-enters the top of the absorption tower to capture SO2, while the saturated slurry containing SO2 at the bottom of the absorption tower enters the desorption tower for desorption after heat exchange, so that the heat in the entire capture process is effectively integrated, greatly reducing energy waste.

[0021] In the second aspect of the present invention, there is provided application of the method for capturing SO2 with a metal organic framework material slurry according to the first aspect of the present invention in the field of SO2 capture.

[0022] Based on the above technical scheme, the design concept and principle of the present invention is that the MOF slurry absorbent is used to capture SO2. Compared with the simple adsorption and capture of SO2 by porous materials, the MOF particles are made to flow, and the whole process can be operated continuously to achieve continuous capture of SO2. The MOF slurry absorbent enters the analytical device for desorption and then re-enters the reaction device to capture SO2. At the same time, heat integration can be achieved to reduce energy consumption.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention provides a method for capturing SO2 using a metal organic framework material slurry, which has the advantages of simple slurry preparation, high absorption capacity, easy desorption, low loss rate and reusability.

[0024] The present invention provides an application of a method for capturing SO2 using a metal organic framework material slurry, which is simple and easy to implement and has broad application prospects in the field of SO2 capture. DETAILED DESCRIPTION

[0025] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0026] Example 1 The method for capturing SO2 using metal organic framework material slurry comprises the following steps: S1. Add 4.5 g ZIF-8 into a beaker, and then weigh 25.5 g polyethylene glycol dimethyl ether and mix them evenly (a total of 30 g), and the solid content of ZIF-8 is 15 wt.%, to form a composite MOF slurry absorbent; S2. Add the MOF slurry absorbent to the reactor. To ensure that the reactor is in a closed state, use a vacuum pump to evacuate the air in the reactor and observe whether the vacuum gauge reading changes. If there is no change, the airtightness is good. Set the temperature in the reactor to 30 °C, turn on the magnetic stirring, open the SO2 gas cylinder, and adjust the pressure reducing valve. After the device is operating normally, if the pressure in the reactor no longer changes, it is considered to have reached gas-liquid equilibrium, that is, absorption saturation, and a saturated slurry is obtained. After equilibrium, vacuum desorb the MOF slurry absorbent at 80 °C and reuse it.

[0027] When the application scenario of this method changes from a laboratory environment to the continuous capture of SO2 in an industrial scale, technicians in this field can implement it by using a device of corresponding scale according to actual conditions. At this time, heat integration is achieved by heat exchange between the absorption tower and the desorption tower through a heat exchanger. In S2, the MOF slurry absorbent in the absorption tower enters the absorption tower from the top of the tower to absorb SO2, and the absorbed saturated slurry enters the heat exchanger, exchanges heat with the MOF slurry absorbent coming out of the bottom of the desorption tower, and then re-enters the top of the absorption tower to capture SO2, while the saturated slurry containing SO2 at the bottom of the absorption tower enters the analysis tower for desorption after heat exchange, so that the heat in the entire capture process is effectively integrated and SO2 is captured continuously.

[0028] Example 2 This embodiment is basically the same as Embodiment 1, except that the MOF material type used in this embodiment is ZIF-67.

[0029] Example 3 This embodiment is basically the same as Embodiment 1, except that the MOF material type used in this embodiment is DTU-67.

[0030] Example 4 This embodiment is basically the same as Embodiment 1, except that the MOF material type used in this embodiment is MOF-74.

[0031] Example 5 This embodiment is basically the same as Embodiment 1, except that the MOF material type used in this embodiment is CAF-20.

[0032] Example 6 The method for capturing SO2 using metal organic framework material slurry comprises the following steps: S1. Add 4.5 g CAF-20 into a beaker, and then weigh 25.5 g ethylene glycol dimethyl ether and mix them evenly (a total of 30 g). The solid content of CAF-20 is 15 wt.%, to form a composite MOF slurry absorbent. S2. Add the MOF slurry absorbent to the reactor. To ensure that the reactor is in a closed state, use a vacuum pump to evacuate the air in the reactor and observe whether the vacuum gauge reading changes. If there is no change, the airtightness is good. Set the temperature in the reactor to 30 °C, turn on the magnetic stirring, open the SO2 gas cylinder, and adjust the pressure reducing valve. After the device is operating normally, if the pressure in the reactor no longer changes, it is considered to have reached gas-liquid equilibrium, that is, absorption saturation, and a saturated slurry is obtained. After equilibrium, vacuum desorb the MOF slurry absorbent at 80 °C and reuse it.

[0033] Example 7 This embodiment is basically the same as Embodiment 6, except that the organic solvent used in this embodiment is diethylene glycol dimethyl ether.

[0034] Test Example 1 This test example records the effects of different MOF slurry absorbents in Examples 1-7 on SO2 capture. The results are shown in Table 1.

[0035] Table 1: Effect of different MOF slurry absorbents on SO2 capture

[0036] From the results in Table 1, it can be seen that Example 5 has the best effect. Under the same conditions, the absorption capacity is as high as 42.98 mmol / L. It can be concluded that the CAF-20 / polyethylene glycol dimethyl ether system has the best capture effect, and the slurry composed of CAF-20 and polyethylene glycol dimethyl ether has an advantage in capturing SO2.

[0037] Taking the MOF slurry absorbent of Example 5 as an example, the experimental effect of the slurry in absorbing SO2 after 5 cycles (under similar equilibrium pressure) was statistically analyzed, and the results are shown in Table 2.

[0038] Table 2: Experimental results of 5 times of SO2 absorption by CAF-20 / polyethylene glycol dimethyl ether

[0039] The above results show that this method has good cycle stability and repeated use effect.

[0040] In summary, the SO2 composite absorbent of the present invention has the advantages of simple preparation, high SO2 absorption capacity, good stability, recyclability, low loss rate, etc., and has good application prospects in the field of SO2 capture.

[0041] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for capturing SO2 using a metal organic framework slurry, characterized in that: The steps include: S1. Mixing MOF and an organic solvent to form a composite MOF slurry absorbent; S2. Place the MOF slurry absorbent in a reaction device, introduce SO2 into the reaction device, and absorb it under certain pressure and temperature conditions until the absorption is saturated to obtain a saturated slurry; then desorb the saturated slurry under a certain temperature and vacuum environment to separate SO2 and the MOF slurry absorbent, and recycle the MOF slurry absorbent to absorb SO2.

2. The method for capturing SO2 using a metal organic framework slurry according to claim 1, characterized in that: In S1, MOF includes one of ZIF-8, ZIF-67, CAF-20, DTU-67, and MOF-74.

3. The method for capturing SO2 using a metal organic framework slurry according to claim 1, characterized in that: In S1, the organic solvent includes one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and polyethylene glycol dimethyl ether.

4. The method for capturing SO2 using a metal organic framework slurry according to claim 1, characterized in that: In S1, the mass fraction of MOF in the MOF slurry absorbent is 5 wt.%-20 wt.%.

5. The method for capturing SO2 using a metal organic framework material slurry according to claim 1, characterized in that: In the S2, the absorption temperature is 20-50°C, and the absorption pressure is 0-20 kPa.

6. The method for capturing SO2 using a metal organic framework slurry according to claim 1, characterized in that: In the S2, the absorption time is 1-5 min.

7. The method for capturing SO2 using a metal organic framework slurry according to claim 1, characterized in that: In the above S2, when the pressure in the reaction device remains unchanged, it is considered that the absorption saturation state has been reached.

8. The method for capturing SO2 using a metal organic framework slurry according to claim 1, characterized in that: In the step S2, the desorption temperature is 60-90°C.

9. The method for capturing SO2 using a metal organic framework slurry according to claim 1, characterized in that: In S2, when recycled and reused, the saturated slurry is transported to the desorption device and desorbed under a certain temperature and vacuum environment; wherein, the saturated slurry is transported from the reaction device to the heat exchange device and heat exchanged with the MOF slurry absorbent separated by the desorption device; the saturated slurry after heat exchange is transported to the desorption device for desorption, and the MOF slurry absorbent after heat exchange re-enters the reaction device to capture SO2.

10. Application of the method for capturing SO2 using a metal organic framework material slurry as claimed in any one of claims 1 to 9 in the field of SO2 capture.

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