CN107413166B - Method for treating nitrogen oxide waste gas by recycling carbon-based microporous material - Google Patents
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- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
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- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
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- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
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- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/30—Processes for preparing, regenerating, or reactivating
- B01J20/34—Regenerating or reactivating
- B01J20/3416—Regenerating or reactivating of sorbents or filter aids comprising free carbon, e.g. activated carbon
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- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/30—Processes for preparing, regenerating, or reactivating
- B01J20/34—Regenerating or reactivating
- B01J20/345—Regenerating or reactivating using a particular desorbing compound or mixture
- B01J20/3475—Regenerating or reactivating using a particular desorbing compound or mixture in the liquid phase
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- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/30—Processes for preparing, regenerating, or reactivating
- B01J20/34—Regenerating or reactivating
- B01J20/3483—Regenerating or reactivating by thermal treatment not covered by groups B01J20/3441 - B01J20/3475, e.g. by heating or cooling
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D2259/40—Further details for adsorption processes and devices
- B01D2259/40083—Regeneration of adsorbents in processes other than pressure or temperature swing adsorption
- B01D2259/40088—Regeneration of adsorbents in processes other than pressure or temperature swing adsorption by heating
- B01D2259/40092—Regeneration of adsorbents in processes other than pressure or temperature swing adsorption by heating using hot liquid
Abstract
The invention provides a method for treating nitrogen oxide waste gas by recycling a carbon-based microporous material, belongs to the field of nitrogen oxide waste gas treatment, and can efficiently and repeatedly recycle the carbon-based microporous material to adsorb the nitrogen oxide waste gas at normal temperature. The method for treating the nitrogen oxide waste gas by recycling the carbon-based microporous material comprises the following steps: (1) stacking the carbon-based microporous material in an adsorption column, and introducing nitrogen oxide waste gas at normal temperature for adsorption; (2) after adsorption, taking out the carbon-based microporous material adsorbing the nitrogen oxide waste gas, placing the carbon-based microporous material in a reaction kettle, adding a reducing agent, mixing, sealing the reaction kettle, and heating; (3) and (3) cooling after heating is finished, opening the reaction kettle, heating for drying, taking out the dried carbon-based microporous material, cooling to room temperature, accumulating in an adsorption column, and repeating the operations in the steps (1) to (2).
Description
Technical Field
The invention relates to the field of treatment of nitrogen oxide waste gas, in particular to a method for treating nitrogen oxide waste gas by recycling a carbon-based microporous material.
Background
Nitrogen oxides, which are mainly composed of nitric oxide and nitrogen dioxide, can cause environmental problems such as acid rain, photochemical smog, and ozone layer destruction. Nitrogen dioxide is easily dissolved in water or alkali liquor and is easily adsorbed and can be removed by an absorption method, while nitrogen monoxide is used as a supercritical fluid, has stable chemical properties and is difficult to remove by a common alkali liquor absorption method or a urea reduction method, but nitrogen oxides in smoke and automobile exhaust mainly consist of low-concentration nitrogen monoxide. For the treatment of nitrogen oxide waste gas, the selective catalytic reduction method is mainly used in industry, and the method uses ammonia as a reducing agent and reduces nitric oxide under the action of a catalyst, however, the method needs higher reaction temperature (300-. There are currently adsorbents for the treatment of nitric oxide at ambient temperature, e.g. mesoporous metal oxides, such as MnO2However, such adsorbents are only suitable for handling low concentrations of nitric oxide, e.g., less than 20ppm, and the metal oxides are readily converted to metal nitrates resulting in reduced adsorption performance.
AC. The microporous carbon materials such as ACF and the like have wide raw material sources, large specific surface area and rich micropores, so that the microporous carbon materials have excellent adsorption performance, and compared with metal oxide mesoporous adsorbents, the micropores such as AC and ACF and the like have the functions of adsorbing and oxidizing nitric oxide at the same time, and oxidize the nitric oxide into nitrogen dioxide which is easy to adsorb; has higher removal rate for higher concentration nitric oxide (concentration is about 500 ppm). The existing research shows that when the mass flow ratio of the activated carbon to the flow rate is 5g/l, the concentration of nitric oxide is 1000ppm, and the relative humidity is zero, the removal rate of the nitric oxide can reach 88%. In the presence of relative humidity, the capacity of the carbon-based microporous material to oxidize nitric oxide is obviously reduced, but since adsorption and oxidation are simultaneously performed during a period of time from the beginning of the reaction, the carbon-based microporous material such as AC, ACF and the like has a strong capacity to remove nitric oxide in exhaust gas for a certain period of time even in the presence of relative humidity.
However, the carbon-based microporous materials such as AC, ACF and the like have poor reusability, because the surface of the carbon-based material is easily oxidized by nitrogen dioxide-like complexes formed by nitric oxide and oxygen to form acidic oxygen-containing functional groups, and the acidic oxygen-containing functional groups are not beneficial to nitric oxide adsorption, the adsorption performance of the carbon-based microporous material is increasingly poor along with the increase of cycle times, researches show that the carbon-based microporous material loses the adsorption capacity to the nitric oxide and only has the oxidation capacity after being heated and cycled for 2-3 times, but the carbon-based microporous material cannot achieve a high removal rate only by the oxidation capacity in the presence of relative humidity. The existing research is mainly carried out under the condition that the relative humidity is zero, and the related achievement of adsorbing the nitrogen oxides, particularly the nitric oxide in the exhaust gas by efficiently and repeatedly utilizing the carbon-based microporous material is not available.
Disclosure of Invention
The invention aims to provide a method for treating nitrogen oxide waste gas by recycling a carbon-based microporous material, which can efficiently and repeatedly recycle the carbon-based microporous material to adsorb nitric oxide in the nitrogen oxide waste gas at normal temperature, saves cost, improves the utilization rate of the carbon-based microporous material, and keeps or even improves the adsorption efficiency of the carbon-based microporous material.
The invention relates to a method for treating nitrogen oxide waste gas by recycling a carbon-based microporous material, which comprises the following steps:
(1) stacking the carbon-based microporous material in an adsorption column, and introducing nitrogen oxide waste gas at normal temperature for adsorption;
(2) after adsorption, taking out the carbon-based microporous material adsorbing the nitrogen oxide waste gas, placing the carbon-based microporous material in a reaction kettle, adding a reducing agent, mixing, sealing the reaction kettle, and heating;
(3) and (3) cooling after heating is finished, opening the reaction kettle, heating for drying, taking out the dried carbon-based microporous material, cooling to room temperature, accumulating in an adsorption column, and repeating the operations in the steps (1) to (2).
Specifically, the reducing agent is an ammonia solution. The mass ratio of the volume of the ammonia water solution to the carbon-based microporous material is more than or equal to 1:4ml/g, and the mass concentration of the ammonia water solution is more than or equal to 5%.
As a preferable scheme, the specific step of heating in the step (2) is to seal the reaction kettle, then place the sealed reaction kettle in an oven with the temperature of less than or equal to 200 ℃ to heat for more than or equal to 20min, and more preferably, the temperature of the oven is 180-.
Alternatively, the temperature for reheating and drying in step (3) is 120-.
As an alternative, the grain diameter of the carbon-based microporous material is less than or equal to 10 meshes.
Alternatively, the nitrogen oxide off-gas is a mixed off-gas of nitrogen monoxide and nitrogen dioxide or a nitrogen monoxide off-gas.
As an alternative, the relative humidity of the nitrogen oxide exhaust gas is 0-60%.
Compared with the prior art, the invention has the beneficial effects that:
1. by utilizing the promotion effect of the temperature in the heated closed space on the reaction, compared with the method of reducing the adsorbed nitric oxide by utilizing the reducing agent at normal temperature, the reduction reaction in the reaction kettle is quicker and more thorough, the volume of the required reducing solution is smaller than that of the solution required for absorbing and reducing at normal temperature, at least 80 percent of adsorption cost is saved, and meanwhile, the efficiency is improved;
2. compared with the prior art that the reduction reaction is carried out at the temperature of 300-;
3. compared with the condition that the adsorption performance of the adsorbent is reduced after the nitric oxide is absorbed and reduced at normal temperature in the prior art, the adsorption performance of the carbon-based microporous material is improved after the nitric oxide is reduced in the reaction kettle, and the high-performance cyclic utilization of the carbon-based microporous material is realized;
4. the invention has higher removal capability to the nitrogen oxide waste gas with zero relative humidity and even with non-zero relative humidity;
5. because the reduction reaction is carried out in a closed space, the reducing agent which is not completely reacted can be recovered, and the cost is further saved.
6. Compared with the existing method for absorbing the nitrogen oxide waste gas by using solutions such as alkali solution and the like, the method disclosed by the invention avoids the problems that a large amount of waste liquid is generated and needs to be recycled, and has the advantages of simple steps, low cost and high safety.
Drawings
FIG. 1 is a graph showing the transient removal rate of nitric oxide with the number of times of using activated carbon in the case of regenerating activated carbon with ammonia water under heating conditions in the reaction vessel according to example 1 of the present invention;
FIG. 2 is a graph showing the transient removal rate of nitric oxide with the number of times of use of activated carbon in the case of regenerating activated carbon using ammonia water at normal temperature according to comparative example 1 of the present invention;
FIG. 3 is a graph showing the transient removal rate of nitric oxide with the number of times of using activated carbon in comparative example 2 according to the present invention in which activated carbon is regenerated by a thermal desorption method;
FIG. 4 is a graph showing the change of the total removal rate of nitrogen monoxide with the number of times of using activated carbon within 150min when the activated carbon is regenerated using ammonia water under heating conditions in the reaction vessel of example 1 of the present invention;
FIG. 5 is a graph showing the change of the total removal rate of nitrogen monoxide in 150min with the number of times of use of activated carbon in the case of regenerating activated carbon using ammonia water at normal temperature according to comparative example 1 of the present invention;
FIG. 6 is a graph showing the change of the total removal rate of nitrogen monoxide with the number of times of use of activated carbon within 150min in the case of the method of comparative example 2 of the present invention in which activated carbon is regenerated by a thermal desorption method.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention provides a method for treating nitrogen oxide waste gas by recycling a carbon-based microporous material, which comprises the following steps:
s1, the carbon-based microporous material is stacked in an adsorption column, and nitrogen oxide waste gas is introduced at normal temperature for adsorption.
In the step, the carbon-based microporous material is used for adsorbing the nitrogen oxide waste gas at normal temperature, and the mass of the carbon-based microporous material and the volume ratio of the nitrogen oxide waste gas can be correspondingly adjusted according to the concentrations of nitrogen oxides such as nitric oxide, nitrogen dioxide and the like in the carbon-based microporous material and the nitrogen oxide waste gas. Generally, in adsorption, the larger the addition amount of the carbon-based microporous material is, the better the adsorption effect is, but the cost is high, and the smaller the volume fraction of the nitrogen oxide in the nitrogen oxide waste gas is, the better the adsorption effect is, and a large amount of carbon-based microporous material is inevitably needed for adsorbing the high-concentration nitrogen oxide waste gas. It should be noted that, the material of the present invention and the adsorption column are filled with nitrogen oxide waste gas for adsorption, and other industrial adsorption methods and devices in the field can be used in the method of the present invention, so as to realize the adsorption of the carbon-based microporous material on the nitrogen oxide waste gas.
And S2, taking out the carbon-based microporous material adsorbing the nitrogen oxide waste gas after adsorption is finished, putting the material into a reaction kettle, adding a reducing agent solution, mixing, sealing the reaction kettle, and heating.
In the step, the carbon-based microporous material for adsorbing the nitrogen oxide waste gas and the reducing agent are heated in the closed reaction kettle, the reduction effect is good, the nitrogen oxide can be reduced into nitrogen and water, the reduction reaction in the reaction kettle is rapid and thorough by utilizing the promotion effect of the temperature in the closed space after heating on the reaction, and the adsorption performance of the reduced carbon-based microporous material is not reduced but improved to some extent. It should be noted that, due to the sealing reaction, the heating temperature in this step is lower than the heating temperature of the conventional reduction reaction in the art, and the corresponding reaction can be completed.
S3, cooling after heating, opening the reaction kettle, heating again for drying, taking out the dried carbon-based microporous material, cooling to room temperature, accumulating in an adsorption column, and repeating the operation of the steps S1-S2.
In the step, nitrogen oxides adsorbed by the carbon-based microporous material, particularly nitrogen monoxide which is difficult to treat, are converted into a small amount of nitrogen and water through a reduction reaction, the adsorption performance of the carbon-based microporous material can be recovered after drying and cooling, the carbon-based microporous material can be repeatedly utilized, and heating desorption can be continuously carried out after adsorption. Since the carbon-based microporous material may contain moisture and unreacted reducing agent after being taken out of the reaction vessel, the moisture and unreacted reducing agent may be removed by drying, but it is understood that the moisture and the reducing agent may be removed by other conventional means in the art. It should be noted that nitrogen can be directly volatilized after the reaction kettle is opened in the small-batch nitrogen oxide waste gas treatment, and the reaction kettle can be connected with a nitrogen treatment device to recycle nitrogen in the large-batch or even industrialized treatment process.
In a specific embodiment, the reducing agent is an ammonia water solution, and more preferably, the mass ratio of the volume of the ammonia water solution to the carbon-based microporous material is more than or equal to 1:4ml/g, and the mass concentration of the ammonia water solution is more than or equal to 5%. Under the above preferred conditions, the ratio of the aqueous ammonia solution to the carbon-based microporous material can promote the reduction of nitrogen oxides, particularly nitric oxide, adsorbed in the carbon-based microporous material, and it is understood that any nitric oxide reducing agent commonly used in the art can be used for the reaction of the carbon-based microporous material. The proportion is optimized according to the reaction of the carbon-based microporous material adsorbed with the nitric oxide and the ammonia water solution, but in the actual reaction process, the proportion of the ammonia water can be increased or the proportion of the carbon material can be increased according to the implementation requirement when the ammonia water is volatile or the carbon material is too much. In order to ensure the recycling of the carbon material, the mass ratio of the volume of the ammonia water solution to the carbon-based microporous material can be 1:4ml/g or more than 1:4ml/g, such as 1:3ml/g, 1:2ml/g, 1:1ml/g and 2:1 ml/g. As for the concentration of the aqueous ammonia solution, the mass concentration of the aqueous ammonia solution commonly used in the art can be used for the reduction reaction of the present invention, and it can be understood that the higher the mass concentration of the aqueous ammonia solution is, the smaller the volume amount is required, but the reaction effect of the aqueous ammonia solution with too low concentration is not as the aqueous ammonia solution within the mass concentration range of the aqueous ammonia solution defined by the present invention.
In a preferred embodiment, the heating in step (2) is specifically performed by sealing the reaction kettle, and then placing the sealed reaction kettle in an oven with the temperature of less than or equal to 200 ℃ for heating for more than or equal to 20 min. Compared with the existing heating temperature of about 400 ℃, the heating temperature of the method is reduced by half, and the desorption effect is better than that of the existing heating desorption method. However, in order to ensure the smooth progress of the desorption reaction, the heating temperature is too low to achieve a good desorption effect. As a more preferred example, the temperature of the oven is 180-200 deg.C, and the specific temperature may be 180 deg.C, 185 deg.C, 190 deg.C, 195 deg.C, 200 deg.C. It is understood that the temperature of the oven may also be a reasonable temperature such as 150 deg.C or the like slightly below 180 deg.C to ensure desorption. It should be noted that the adsorption reaction of the present invention is not large in scale, heating can be performed in an oven, and in a specific industrial operation process, the heating mode can be other common heating modes of a reaction kettle. The heating time can be adjusted according to the using amount of the carbon-based microporous material, the heating time of the carbon-based microporous material can be 20min in the test stage, and the heating reaction time can be prolonged according to the actual reaction condition due to the large using amount of the carbon-based microporous material in the industrial operation stage.
In an alternative embodiment, the temperature for drying in step (3) is 120-. Based on different carbon-based microporous materials, the heating and drying temperature is any temperature capable of drying the carbon-based microporous materials.
In an optional embodiment, the particle size of the carbon-based microporous material is less than or equal to 10 meshes, the particle size of the carbon-based microporous material is small, the adsorption effect is high, and the contact area with the reducing agent is large, so that the desorption reaction of the carbon-based microporous material is facilitated, but it can be understood that the corresponding adsorption and desorption reactions can be completed when the particle size of the carbon-based microporous material is greater than 10 meshes.
In an alternative embodiment, the nitrogen oxide exhaust gas is a mixed exhaust gas of nitrogen monoxide and nitrogen dioxide or a nitrogen monoxide exhaust gas. The invention focuses on the adsorption and treatment of nitric oxide off-gas, since the adsorption and removal of nitrogen dioxide is relatively easy in the art.
In an alternative embodiment the relative humidity of the nitrogen oxide exhaust gas is 0-60%. The nitrogen oxide waste gas treatment is usually carried out under the condition that the humidity is zero, but the relative humidity of the waste gas in the actual operation cannot be zero. Although the relative humidity of the nitrogen oxide exhaust gas is given in the present invention, the present invention is not limited to this.
In order to more clearly describe the method for recycling the carbon-based microporous material to treat the nitrogen oxide exhaust gas provided by the embodiment of the invention in detail, the following description will be made with reference to specific embodiments.
Preparing simulated gas: 10000ppm nitric oxide with the flow rate of 40ml/min and 99.999 percent nitrogen with the flow rate of 360ml/min are introduced into a gas mixing bottle together to be mixed, air is blown into a wide-mouth bottle filled with water at the flow rate of 400ml/min by using an air pump, the air after bubbling is mixed with the mixed gas of the nitric oxide and the nitrogen in the wide-mouth bottle to form 800ml/min simulated gas, and the distance between the inlet of the mixed gas of the nitric oxide and the nitrogen and the inlet of the air is more than 15 cm.
(II) adsorbing nitric oxide by using an adsorption column: 5g of 10-20 meshes of active carbon is tightly packed in a quartz tube adsorption column with the diameter of 4cm, and the space velocity is 3600h through calculation-1And two ends of the adsorption column are compacted by disc-shaped nylon cloth and rubber plugs with holes, the two ends of the adsorption column are firstly closed, and the prepared simulation gas is discharged through a bypass and is connected to an inlet of a KM940 smoke gas analyzer. Until the concentration of nitric oxide reaches the normal valueDetecting and recording the relative humidity of the exhaust gas by using a hygrometer after the calculated value, opening inlets at two ends of the adsorption column, closing a bypass, starting timing, recording the concentration of nitric oxide once every 10min, totally adsorbing for 150min, and calculating the transient removal rate η of nitric oxide, wherein η is C/COC is the outlet concentration, COIs the inlet concentration; and calculating the amount of adsorbed nitric oxide by integration to calculate the overall removal rate delta of nitric oxide within 150min, wherein delta is m/moM is the amount of adsorbed nitric oxide, moIs the amount of nitric oxide entering the adsorption column.
The method is used for treating the nitrogen oxide waste gas at normal temperature. Experiments show that compared with the method for reducing the nitric oxide adsorbed in the activated carbon by using the reducing agent at normal temperature, the method for reducing the nitric oxide adsorbed in the activated carbon in the reaction kettle can reduce the adsorbed nitric oxide more quickly and thoroughly, and the adsorption performance of the activated carbon in the subsequent cyclic adsorption process is improved. Because the reduction reaction is carried out in a closed space, the possibility of recovering the incompletely reacted reducing agent is provided.
Example 1: preparing the simulated gas according to the method (I), measuring that the relative humidity is 40%, the volume fraction of oxygen is 10.3% and the volume fraction of nitric oxide is 520ppm, enabling the gas to pass through the adsorption column in the method (II), simultaneously starting timing, recording the concentration of nitric oxide once every 10min, totally adsorbing for 150min, and drawing a curve of the transient removal rate of nitric oxide along with the change of time (see figure 1).
Taking out the activated carbon after adsorbing for 150min, placing the activated carbon in a reaction kettle, adding 1.25ml of ammonia water solution with the mass concentration of 7%, mixing, placing the closed reaction kettle in a drying oven at 180 ℃, stopping heating after 30min, opening the reaction kettle after cooling, reheating and drying for 90min at 180 ℃, taking out the dried activated carbon, cooling to room temperature, repeating the steps, carrying out adsorption test by using regenerated activated carbon, making a curve (shown in figure 1) of transient removal rate changing along with time, calculating the integral removal rate of nitric oxide within 150min (shown in figure 4), and repeating the adsorption test for 5 times.
Example 2: a model gas was prepared by the method (I) above, the relative humidity was measured to be 40%, the volume fraction of oxygen was measured to be 10.3%, and the volume fraction of nitric oxide was measured to be 520ppm, and the gas was passed through the adsorption column (II) above.
And taking out the activated carbon after adsorption for 150min, placing the activated carbon in a reaction kettle, adding the activated carbon and 2.5ml of 7% ammonia water solution, mixing, sealing the reaction kettle, placing the reaction kettle in a 200 ℃ oven, stopping heating after 30min, cooling, opening the reaction kettle, heating and drying for 90min at 180 ℃, taking out the dried activated carbon, cooling to room temperature, and repeating the steps to perform adsorption by using regenerated activated carbon.
Example 3: a model gas was prepared by the method (I) above, the relative humidity was measured to be 40%, the volume fraction of oxygen was measured to be 10.3%, and the volume fraction of nitric oxide was measured to be 520ppm, and the gas was passed through the adsorption column (II) above.
And taking out the activated carbon after adsorbing for 150min, placing the activated carbon in a reaction kettle, adding 5ml of ammonia water solution with the mass concentration of 7%, mixing, sealing the reaction kettle, placing the reaction kettle in a baking oven at 190 ℃, stopping heating after 30min, opening the reaction kettle after cooling, heating and drying for 90min at 180 ℃, taking out the dried activated carbon, cooling to room temperature, and repeating the steps to adsorb by using regenerated activated carbon.
Comparative example 1: preparing the simulated gas according to the method (I), measuring that the relative humidity is 40%, the oxygen volume fraction is 10.3% and the nitric oxide volume fraction is 520ppm, enabling the gas to pass through the adsorption column in the method (II), simultaneously starting timing, recording the nitric oxide concentration every 10min, totally adsorbing for 150min, and making a curve of the transient removal rate changing along with time (see figure 2). Taking out the activated carbon after adsorbing for 150min, placing the activated carbon in a conical flask, adding 10ml of ammonia water solution with the mass concentration of 7%, mixing and sealing, shaking for 60min at normal temperature, filtering out ammonia water, heating the activated carbon at 180 ℃ for 90min, drying, taking out the dried activated carbon, cooling to room temperature, repeating the steps, performing adsorption test by using regenerated activated carbon, making a curve (shown in figure 2) of transient removal rate changing along with time, calculating the integral removal rate of nitric oxide within 150min (shown in figure 5), and repeating the adsorption test for 3 times.
Comparative example 2: preparing a simulated gas according to the method (I), measuring that the relative humidity is 40%, the volume fraction of oxygen is 10.3% and the volume fraction of nitric oxide is 520ppm, enabling the gas to pass through the adsorption column in the method (2), starting timing, recording the concentration of nitric oxide every 10min, totaling adsorption for 150min, and making a curve of the transient removal rate changing along with time (see figure 3). And (3) taking out the activated carbon after adsorption for 150min, heating for 90min at 250 ℃ (250 ℃ is the complete desorption temperature of nitrogen oxides on the activated carbon) to desorb nitric oxide, cooling to room temperature, repeating the steps, performing an adsorption test by using regenerated activated carbon, making a curve (shown in figure 3) of the transient removal rate changing along with time, calculating the integral removal rate (shown in figure 6) of the nitric oxide within 150min, and repeating the adsorption test for 3 times.
By comparing example 1 with comparative example 1 and comparative example 2, and referring to fig. 1-3 and fig. 4-6, it can be seen that fig. 3 and fig. 6 show that the activated carbon regenerated by direct heating desorption has the worst repeated recycling effect, and the adsorption performance of the activated carbon is remarkably reduced compared with that after the activated carbon is regenerated by ammonia water at normal temperature or directly heated. Fig. 2 and 5 show that the adsorption performance of the activated carbon regenerated by ammonia water at normal temperature is also reduced, and the reduction speed is slower than that of the activated carbon regenerated by desorption by direct heating. And figures 1 and 4 show that the reduction reaction in the reaction kettle is quicker and more thorough by utilizing the reaction kettle to regenerate the activated carbon, after the nitric oxide is reduced in the reaction kettle, the adsorption performance of the activated carbon on the nitric oxide is not lost but improved, the use times are obviously increased, and the removal effect is good. The volume of the required reducing solution is smaller than that required by absorption reduction by ammonia water at normal temperature. Because the reduction reaction is carried out in a closed space, the possibility of recovering the incompletely reacted reducing agent is provided. The adsorption effect is not reduced when the number of times of repetition is large, and the adsorption effect is excellent compared with the regeneration of the activated carbon by ammonia water and the regeneration of the activated carbon by direct heating desorption at normal temperature.
Claims (4)
1. The method for treating the nitrogen oxide waste gas by recycling the carbon-based microporous material is characterized by comprising the following steps of:
(1) stacking the carbon-based microporous material in an adsorption column, and introducing nitrogen oxide waste gas at normal temperature for adsorption, wherein the particle size of the carbon-based microporous material is less than or equal to 10 meshes;
(2) after adsorption, taking out the carbon-based microporous material adsorbing the nitrogen oxide waste gas, placing the material in a reaction kettle, adding a reducing agent, mixing, sealing the reaction kettle, placing the sealed reaction kettle in an oven with the temperature of 180-200 ℃, heating for 20-30min, wherein the reducing agent is an ammonia water solution, and the relative humidity of the nitrogen oxide waste gas is 40-60%;
(3) and (3) after heating, opening the reaction kettle, heating for drying, taking out the dried carbon-based microporous material, cooling to room temperature, accumulating in an adsorption column, and repeating the operations in the steps (1) to (2).
2. The method for recycling the carbon-based microporous material to treat the nitrogen oxide waste gas as claimed in claim 1, wherein the mass ratio of the volume of the ammonia water solution to the carbon-based microporous material is greater than or equal to 1:4ml/g, and the mass concentration of the ammonia water solution is greater than or equal to 5%.
3. The method for recycling the exhaust gas containing nitrogen oxides from carbon-based microporous materials as claimed in claim 1, wherein the temperature for reheating and drying in step (3) is 120-180 ℃.
4. The method for recycling carbon-based microporous materials to treat nitrogen oxide exhaust gas according to any one of claims 1 to 3, wherein the nitrogen oxide exhaust gas is a mixed exhaust gas of nitrogen monoxide and nitrogen dioxide or a nitrogen monoxide exhaust gas.
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| CN1227506A (en) * | 1996-07-11 | 1999-09-01 | 三菱重工业株式会社 | Exhaust gas denitration method |
| CN102068960A (en) * | 2010-12-11 | 2011-05-25 | 上海纳米技术及应用国家工程研究中心有限公司 | Regeneration method of honeycomb activated carbon absorbent for absorbing nitric oxide |
| CN102688689A (en) * | 2012-06-05 | 2012-09-26 | 山西英诺普环保咨询有限公司 | Flue gas denitration method |
| CN204447762U (en) * | 2015-02-06 | 2015-07-08 | 宁波喆能节能科技有限公司 | The absorption tower that a kind of reduction efficiency is high |
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| CN101879435B (en) * | 2010-06-08 | 2013-05-08 | 华东理工大学 | High-adsorption-capacity room-temperature nitrogen oxide adsorbent and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1227506A (en) * | 1996-07-11 | 1999-09-01 | 三菱重工业株式会社 | Exhaust gas denitration method |
| CN102068960A (en) * | 2010-12-11 | 2011-05-25 | 上海纳米技术及应用国家工程研究中心有限公司 | Regeneration method of honeycomb activated carbon absorbent for absorbing nitric oxide |
| CN102688689A (en) * | 2012-06-05 | 2012-09-26 | 山西英诺普环保咨询有限公司 | Flue gas denitration method |
| CN204447762U (en) * | 2015-02-06 | 2015-07-08 | 宁波喆能节能科技有限公司 | The absorption tower that a kind of reduction efficiency is high |
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