CN110327911B - Preparation method of catalyst for removing 1, 2-dichlorobenzene waste gas - Google Patents
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Abstract
The invention discloses a preparation method of a catalyst for removing 1, 2-dichlorobenzene waste gas, which comprises the following steps of firstly, placing chromium-containing waste liquid in a sealed container, and aerating carbon dioxide into the container to obtain carbonated chromium-containing waste liquid; then adding ferrous carbonate into the carbonated chromium-containing waste liquid, and stirring under sealed condition to obtain reduced carbonated chromium-containing waste liquid; and finally, adding calcium hydroxide into the reduced and carbonated chromium-containing waste liquid, stirring under a sealed condition until a precipitate is generated, carrying out solid-liquid separation, and placing the solid in an atmosphere furnace for thermal decomposition treatment to obtain the 1, 2-dichlorobenzene waste gas removal catalyst. According to the invention, the catalyst for removing the 1, 2-dichlorobenzene waste gas is prepared by recycling the chromium-containing waste liquid, so that a harmless treatment link of the chromium-containing waste liquid is saved, and a new idea is provided for treatment and utilization of the chromium-containing waste liquid; solves the problem of carbon monoxide pollution generated in the catalytic oxidation process of the traditional 1, 2-dichlorobenzene waste gas.
Description
Technical Field
The invention relates to a preparation method of a waste gas removal catalyst, in particular to a preparation method of a 1, 2-dichlorobenzene waste gas removal catalyst.
Background
The chromium-containing waste liquid comes from a plurality of industries such as metallurgy, electroplating, leather printing and dyeing and the like, and the stealing discharge or improper disposal of the chromium-containing waste liquid can seriously threaten the surrounding ecological environment. The chromium in the water body generally exists in two forms of trivalent (Cr (III)) and hexavalent (Cr (VI)), the toxicity of the hexavalent chromium is about 100 times of that of the trivalent chromium, and the maximum limit of the content of the hexavalent chromium in the drinking water is 0.05 mg/L. Generally, when the content of hexavalent chromium in water is more than 0.1mg/L, toxic action can be generated to human body. At present, the treatment method of the chromium-containing waste liquid mainly comprises the following steps: the electric repairing and removing method, the adsorption method, the chemical precipitation method and the like, but the methods have high treatment cost and poor treatment effect, and the problem of secondary pollution is easily caused in the treatment process. For the resource utilization of chromium-containing waste liquid, at present, the method focuses on adding a cationic reagent to enable Cr (VI) to generate precipitates or reduce the Cr (VI) into Cr (III), and adding alkali or sulfate radicals to enable the Cr (III) to generate precipitates for recycling. However, the traditional recovery method not only causes low recovery efficiency of chromium, but also obtains chromium products with poor quality and low purity, and is difficult to directly put on the market or apply in engineering.
1, 2-dichlorobenzene is generally used as an industrial solvent or cleaning agent in the manufacturing industries of wax, resin, rubber and the like. 1, 2-dichlorobenzene is easy to volatilize, can be introduced into a human body through oral inhalation and skin permeation to cause poisoning, and is classified as three carcinogens by the world health organization international cancer research organization. In the use process of the 1, 2-dichlorobenzene, the waste gas of the 1, 2-dichlorobenzene needs to be collected in time and is removed by catalytic incineration. In the catalytic incineration process, when the incineration conditions are determined, the removal efficiency of the 1, 2-dichlorobenzene depends on the catalytic characteristics of the catalyst, but the traditional catalyst can generate harmful carbon monoxide in the process of catalytically oxidizing the 1, 2-dichlorobenzene.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the problems, the invention provides a method for preparing a catalyst for removing 1, 2-dichlorobenzene waste gas by using chromium-containing waste liquid. Not only realizes the resource utilization of the chromium-containing waste liquid, but also can realize the efficient removal of the waste gas of the 1, 2-dichlorobenzene.
The technical scheme is as follows: the preparation method of the catalyst for removing the 1, 2-dichlorobenzene waste gas comprises the following steps:
firstly, putting the chromium-containing waste liquid into a sealed container, and aerating carbon dioxide into the container to obtain carbonated chromium-containing waste liquid; then adding ferrous carbonate into the carbonated chromium-containing waste liquid, and stirring under sealed condition to obtain reduced carbonated chromium-containing waste liquid; and finally, adding calcium hydroxide into the reduced and carbonated chromium-containing waste liquid, stirring under a sealed condition until a precipitate is generated, carrying out solid-liquid separation, and placing the solid in an atmosphere furnace for thermal decomposition treatment to obtain the 1, 2-dichlorobenzene waste gas removal catalyst.
Preferably, after the solid is thermally decomposed, the solid powder is taken out and subjected to a grinding treatment, so that the 1, 2-dichlorobenzene exhaust gas removal catalyst can have a larger specific surface area.
The unit volume ratio of the carbon dioxide to the chromium-containing waste liquid is 0.5-3: 1, and the preferable ratio is 1-2: 1.
The molar ratio of ferrous ions in the ferrous carbonate to hexavalent chromium ions in the chromium-containing waste liquid is 4-8: 1, and the preferable ratio is 5-7: 1.
The molar ratio of ferrous ions in the ferrous carbonate to calcium ions in the calcium hydroxide is 1: 2-6, and more preferably 1: 3-5.
The thermal decomposition treatment is carried out for 1-2 h at 900-1000 ℃.
And (3) carbon dioxide is exposed into the chromium-containing waste liquid, and the carbon dioxide is hydrolyzed to generate hydrogen ions and carbonate. Under the coordination of carbonate, ferrous carbonate powder is gradually dissolved into the chromium-containing waste liquid, and ferrous ions react with hexavalent chromium in the waste liquid to generate trivalent chromium and ferric ions. The calcium hydroxide dissolved in the reduced and carbonated chromium-containing waste liquid dissociates to generate hydroxide radical and calcium ion, on one hand, the calcium ion reacts with the carbonate radical ion to generate calcium carbonate precipitate, and on the other hand, the ferrous ion, the ferric ion and the trivalent chromium ion react with the hydroxide radical to generate ferrous hydroxide, ferric hydroxide, chromium hydroxide and various iron-chromium coprecipitates. In the high-temperature thermal decomposition process, calcium carbonate, hydroxide precipitate and iron-chromium coprecipitate are heated to decompose to generate ferroferric oxide (Fe)3O4) Iron (III) oxide2O3) Chromium oxide (Cr)2O3) Calcium oxide (CaO) oxide products of various intergrown structures. Several oxides are uniformly distributed and connected by means of crystal lattice fusion, and the carbon dioxide produced by decomposition of calcium carbonateAnd the water vapor generated by the decomposition of the hydroxide precipitate is released continuously, so that the symbiotic oxide structure product has developed pores. Therefore, in the process of removing the 1, 2-dichlorobenzene gas, the catalyst can be removed to quickly capture 1, 2-dichlorobenzene molecules so as to enable the 1, 2-dichlorobenzene molecules to be adsorbed on the surfaces and in the pores of the particles. Meanwhile, as the crystalline states and potentials of various oxides in the symbiotic structure are different, in the process of removing the waste gas of the 1, 2-dichlorobenzene, the potential difference between the oxides enables chloride ions on the 1, 2-dichlorobenzene to quickly fall off from a benzene ring, and calcium oxide is transferred to ferric oxide to generate ferric trichloride. The chromic oxide primarily oxidizes benzene rings through catalytic oxidation to generate carbon monoxide, carbon dioxide and water. The generated carbon monoxide is retained in the symbiotic structure and is further oxidized by ferroferric oxide and ferric oxide to finally generate carbon dioxide. The generated carbon dioxide can also be recycled for realizing the carbonation disposal of the chromium-containing waste liquid. The method converts the chromium-containing waste liquid into a valuable catalyst product, thereby not only meeting the treatment requirement of the chromium-containing waste liquid, but also increasing the economic benefit and meeting the requirement of the catalytic removal performance of the catalyst.
Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: (1) according to the invention, the catalyst for removing the 1, 2-dichlorobenzene waste gas is prepared by recycling the chromium-containing waste liquid, the removal rate of chromium in the waste liquid is as high as 99.58%, the conversion rate of the 1, 2-dichlorobenzene waste gas is as high as 95.76%, the link of harmless treatment of the chromium-containing waste liquid is omitted, and a new idea is provided for the treatment and utilization of the chromium-containing waste liquid; (2) the problem of carbon monoxide pollution generated in the catalytic oxidation process of the waste gas of the 1, 2-dichlorobenzene in the prior art is solved; (3) the preparation method has the advantages of simple preparation operation process and low equipment requirement, and can be directly popularized in a commercial mode.
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FIG. 1 is a flow diagram of the preparation of the present invention for removing catalyst;
FIG. 2 is a schematic diagram of the use of the removal catalyst of the present invention for the removal of 1, 2-dichlorobenzene waste gas.
Detailed Description
The invention is further described below with reference to the figures and examples.
Example 1
Influence of carbon dioxide gas exposure unit volume on chromium removal rate in waste liquid and catalyst removal performance of 1, 2-dichlorobenzene waste gas
Waste liquid disposal and preparation of the catalyst for removing 1, 2-dichlorobenzene waste gas: as shown in fig. 1, a unit volume of the chromium-containing waste liquid is placed in a sealed container, and then 0.5, 0.7, 0.9, 1, 1.5, 2, 2.2, 2.5 and 3 unit volumes of carbon dioxide gas are respectively aerated into the container to obtain carbonated chromium-containing waste liquid; weighing ferrous carbonate powder according to the molar ratio of ferrous ions to hexavalent chromium ions in the chromium-containing waste liquid of unit volume of 5:1, placing the ferrous carbonate powder into the carbonated chromium-containing waste liquid, and stirring under a sealed condition until the ferrous carbonate powder is completely dissolved to obtain reduced carbonated chromium-containing waste liquid; weighing calcium hydroxide powder according to the molar ratio of ferrous ions to calcium ions of 1:3, then adding the calcium hydroxide powder into reduced and carbonated chromium-containing waste liquid, stirring under a sealed condition until precipitates are fully generated and uniformly mixed, carrying out solid-liquid separation to obtain the waste liquid and a solid part after the waste liquid and the solid part are arranged, placing the solid part in an atmosphere furnace, treating for 1 hour under the protection of argon or nitrogen and at the temperature of 900 ℃, carrying out a high-temperature thermal decomposition process, taking out the solid powder after the high-temperature thermal decomposition process is finished, and grinding to obtain the catalyst for removing the 1, 2-dichlorobenzene waste gas.
Performance test of the catalyst for removing the 1, 2-dichlorobenzene waste gas: as shown in FIG. 2, the steam generator was first turned on to generate 1, 2-dichlorobenzene gas, then 1, 2-dichlorobenzene gas and balance gas (20% oxygen + 80% nitrogen) were simultaneously introduced into the gas mixing box, after mixing, the concentration of 1, 2-dichlorobenzene gas in the gas mixing box was 100ppmv, and then 1, 2-dichlorobenzene gas was introduced into the fixed bed reactor with a gas flow rate set at 50 mL/min. 200mg of the catalyst for removing the 1, 2-dichlorobenzene waste gas prepared by the method is filled in the middle of the fixed bed reactor, and the temperature of the reactor is controlled at 300 ℃.1, 2-dichlorobenzene gas enters from a gas inlet of the fixed bed reactor, reacts in a catalyst filling area of the fixed bed reactor, and is discharged from a gas outlet after 30 minutes for online detection. The 1, 2-dichlorobenzene gas concentration was determined by GC 1100-gas chromatography (equipped with a flame ionization detector). The gas conversion of 1, 2-dichlorobenzene is calculated according to formula (1), whereinc0Is the gas inlet 1, 2-dichlorobenzene gas concentration, ctThe gas outlet 1, 2-dichlorobenzene gas concentration is shown in Table 1.
Determination of chromium removal rate in waste liquid: the concentration of chromium in the waste liquid was measured according to the standard "determination of total chromium in Water-Dihydrazinodiphenylcarbodihydrazide spectrophotometry" (GBT 7466-1987). The chromium removal rate in the waste liquid is calculated according to the formula (2), wherein cCr0The initial concentration (mg/L) of total chromium in the chromium-containing waste liquid, cCrtThe test results are shown in Table 1 for the total chromium concentration (mg/L) in the treated waste liquid.
TABLE 1 influence of carbon dioxide gas aeration unit volume on chromium removal rate in waste liquid and catalyst removal performance of 1, 2-dichlorobenzene waste gas
As can be seen from table 1, when the carbon dioxide gas exposure is less than 1 unit volume (as shown in table 1, when the carbon dioxide gas exposure is 0.9, 0.7, 0.5 unit volume and lower ratios not listed in table 1), less carbon dioxide is dissolved in the water, resulting in less hydrogen ions and carbonate generated by hydrolysis of carbon dioxide, weaker carbonate coordination, slower dissolution of ferrous carbonate powder, and reduced hexavalent chromium reduction efficiency. After the calcium hydroxide is added, relatively less calcium carbonate and hydroxide precipitates are generated, so that the total chromium removal rate and the generation amount of an oxide with a symbiotic structure for removing the catalyst are influenced, the chromium removal rate is finally lower than 85%, the 1, 2-dichlorobenzene gas conversion rate is lower than 83%, and the chromium removal rate and the 1, 2-dichlorobenzene gas conversion rate are gradually reduced along with the reduction of the unit volume of the carbon dioxide gas. When the exposure amount of the carbon dioxide gas is equal to 1-2 unit volume amounts, the carbon dioxide gas is dissolved in the chromium-containing waste liquid in a proper amount and hydrolyzed to generate a proper amount of hydrogen ions and carbonate, the coordination effect of the carbonate is obvious, ferrous carbonate powder is gradually dissolved in the chromium-containing waste liquid, hexavalent chromium is fully reduced, calcium hydroxide is added to generate a proper amount of calcium carbonate and hydroxide precipitates, so that a proper amount of oxide with a catalyst symbiotic structure is generated, the chromium removal rate is higher than 90%, and the conversion rate of the 1, 2-dichlorobenzene gas is higher than 87%. When the carbon dioxide gas exposure amount is higher than 2 unit volume (as shown in table 1, when the carbon dioxide gas exposure amount is 2.2, 2.5 or 3 unit volume and higher ratio not listed in table 1), the carbon dioxide gas is dissolved in the chromium-containing waste liquid sufficiently, and is hydrolyzed to generate proper amount of hydrogen ions and carbonate, the coordination of carbonate is obvious, the ferrous carbonate powder is gradually dissolved in the chromium-containing waste liquid, the hexavalent chromium is fully reduced, but the chromium removal rate is not obviously changed along with the increase of the unit volume of the carbon dioxide gas exposed, meanwhile, the calcium hydroxide is added into the waste liquid to generate excessive calcium carbonate and hydroxide precipitate, in the high-temperature thermal decomposition process, the calcium carbonate and hydroxide precipitates are not sufficiently decomposed, and the generation of oxide with a symbiotic structure for removing the catalyst is also influenced, so that the conversion rate of the 1, 2-dichlorobenzene gas is gradually reduced along with the increase of the unit volume amount of the carbon dioxide gas exposed. Therefore, in summary, the benefit and the cost are combined, and when the carbon dioxide gas exposure amount is equal to 1-2 unit volume amounts, the method is most beneficial to improving the chromium removal rate in the waste liquid and improving the catalyst removal performance of the 1, 2-dichlorobenzene waste gas.
Example 2
The mole ratio of ferrous ions to hexavalent chromium ions in the chromium-containing waste liquid influences the chromium removal rate in the waste liquid and the performance of the catalyst for removing 1, 2-dichlorobenzene waste gas
Waste liquid disposal and preparation of the catalyst for removing 1, 2-dichlorobenzene waste gas: putting a unit volume of chromium-containing waste liquid into a sealed container, then aerating 2 unit volumes of carbon dioxide gas into the container to obtain carbonated chromium-containing waste liquid, respectively weighing ferrous carbonate powder according to the molar ratio of ferrous ions to hexavalent chromium ions in the unit volume of chromium-containing waste liquid of 4:1, 4.5:1, 4.8:1, 5:1, 6:1, 7:1, 7.2:1, 7.5:1 and 8:1, putting the ferrous carbonate powder into the carbonated chromium-containing waste liquid, stirring the ferrous carbonate powder and the calcium ions under a sealed condition until the ferrous carbonate powder is completely dissolved to obtain reduced carbonated chromium-containing waste liquid, weighing calcium hydroxide powder according to the molar ratio of ferrous ions to calcium ions of 1:4, then adding the calcium hydroxide powder into the reduced chromium-containing carbonated waste liquid, stirring the mixture under a sealed condition until precipitates are fully generated and uniformly mixed to obtain solid-liquid separation, putting the waste liquid and the solid part after all around into an atmosphere furnace, treating the solid part for 1.5 hours under the protection atmosphere of argon or nitrogen and the temperature of 950 ℃, and (3) carrying out a high-temperature thermal decomposition process, taking out solid powder after the high-temperature thermal decomposition process is finished, and grinding to obtain the catalyst for removing the 1, 2-dichlorobenzene waste gas.
The performance test of the catalyst for removing the 1, 2-dichlorobenzene waste gas and the determination of the chromium removal rate in the waste liquid are the same as the example 1, and the test results are shown in the table 2.
TABLE 2 Mole ratio of ferrous ion to hexavalent chromium ion in chromium-containing waste liquid, influence of chromium removal rate in waste liquid and catalyst performance in removing 1, 2-dichlorobenzene waste gas
As shown in Table 2, when the molar ratio of the ferrous ions to the hexavalent chromium ions in the chromium-containing waste liquid is less than 5:1 (as shown in Table 2, when the molar ratio of the ferrous ions to the hexavalent chromium ions in the chromium-containing waste liquid is 4.8:1, 4.5:1, 4:1 and lower ratios not listed in Table 2), less ferrous ions are introduced into the waste liquid, the hexavalent chromium is not sufficiently reduced, so that the amount of chromium precipitates generated after the calcium hydroxide is added is less, the chromium removal rate is lower than 92%, and gradually decreases along with the reduction of the molar ratio of the ferrous ions to the hexavalent chromium ions in the chromium-containing waste liquid, and simultaneously, because the chromium precipitate and the ferric hydroxide precipitate are relatively less, the generation of oxide with a symbiotic structure in the thermal decomposition process is also influenced, so that the conversion rate of the 1, 2-dichlorobenzene gas is lower than 88 percent, and the conversion rate is gradually reduced along with the reduction of the molar ratio of the ferrous ions to the hexavalent chromium ions in the chromium-containing waste liquid. When the molar ratio of the ferrous ions to the hexavalent chromium ions in the chromium-containing waste liquid is 5-7: 1, a proper amount of ferrous ions are introduced into the waste liquid, the hexavalent chromium is fully reduced, calcium hydroxide is added into the waste liquid to generate a large amount of chromium precipitates, the chromium removal rate is higher than 95%, the chromium removal rate is gradually increased along with the increase of the molar ratio of the ferrous ions to the hexavalent chromium ions in the chromium-containing waste liquid, and meanwhile, a proper amount of oxide with a symbiotic structure is generated in the thermal decomposition process, so that the gas conversion rate of the 1, 2-dichlorobenzene is higher than 92%, and the conversion rate is gradually increased along with the increase of the molar ratio of the ferrous ions to the hexavalent chromium ions in the chromium-containing waste liquid. When the molar ratio of the ferrous ions to the hexavalent chromium ions in the chromium-containing waste liquid is higher than 7:1 (for example, when the molar ratio of the ferrous ions to the hexavalent chromium ions in the chromium-containing waste liquid is 7.2:1, 7.5:1, 8:1 and higher ratios not listed in table 2), the ferrous ions introduced into the waste liquid are sufficient, the hexavalent chromium is fully reduced, calcium hydroxide is added into the waste liquid to generate a large amount of chromium precipitates, but is limited by the total chromium concentration in the waste liquid, the chromium ion removal efficiency does not change obviously along with the increase of the molar ratio of ferrous ions to hexavalent chromium ions in the chromium-containing waste liquid, and simultaneously, because excessive carbonate ions and ferrous ions are dissolved in the waste liquid, in the high-temperature thermal decomposition process, the insufficient decomposition of calcium carbonate and the generation of ferrous oxide both influence the output of symbiotic oxide, so that the conversion rate of the 1, 2-dichlorobenzene gas is gradually reduced along with the increase of the molar ratio of the ferrous ions to the hexavalent chromium ions in the chromium-containing waste liquid. Therefore, in summary, the benefits and the cost are combined, and when the molar ratio of the ferrous ions to the hexavalent chromium ions in the chromium-containing waste liquid is 5-7: 1, the method is most beneficial to improving the chromium removal rate in the waste liquid and improving the catalyst removal performance of the 1, 2-dichlorobenzene waste gas.
Example 3
Influence of ferrous ion and calcium ion molar ratio on chromium removal rate in waste liquid and performance of catalyst for removing 1, 2-dichlorobenzene waste gas
Waste liquid disposal and preparation of the catalyst for removing 1, 2-dichlorobenzene waste gas: putting a unit volume of chromium-containing waste liquid into a sealed container, then aerating 2 unit volumes of carbon dioxide gas into the container to obtain carbonated chromium-containing waste liquid, weighing ferrous carbonate powder according to the molar ratio of ferrous ions to hexavalent chromium ions in the unit volume of chromium-containing waste liquid of 7:1, putting the ferrous carbonate powder into the carbonated chromium-containing waste liquid, stirring under sealed conditions until the ferrous carbonate powder is completely dissolved to obtain reduced carbonated chromium-containing waste liquid, weighing calcium hydroxide powder respectively according to the molar ratio of ferrous ions to calcium ions of 1:2, 1:2.5, 1:2.8, 1:3, 1:4, 1:5, 1:5.2, 1:5.5 and 1:6, then adding the calcium hydroxide powder into the reduced carbonated waste liquid, stirring under sealed conditions until precipitates are fully generated and uniformly mixed, carrying out solid-liquid separation to obtain the waste liquid and a solid part after all positions, putting the solid part into an atmosphere furnace, treating for 2 hours under the protection atmosphere of argon or nitrogen and the temperature of 1000 ℃, and (3) carrying out a high-temperature thermal decomposition process, taking out solid powder after the high-temperature thermal decomposition process is finished, and grinding to obtain the catalyst for removing the 1, 2-dichlorobenzene waste gas.
The performance test of the catalyst for removing the 1, 2-dichlorobenzene waste gas and the determination of the chromium removal rate in the waste liquid are the same as the example 1, and the test results are shown in the table 3.
TABLE 3 influence of molar ratio of ferrous ion to calcium ion on chromium removal rate from waste liquid and catalyst performance in removing 1, 2-dichlorobenzene waste gas
As can be seen from table 3, when the molar ratio of the ferrous ions to the calcium ions is higher than 1:3 (as shown in table 3, when the molar ratio of the ferrous ions to the calcium ions is 1:2.8, 1:2.5, 1:2 and higher ratios not listed in table 3), the amount of the calcium hydroxide ions added is smaller, and accordingly, less calcium carbonate, hydroxide precipitate and iron-chromium coprecipitate are generated, so that part of trivalent chromium is still retained in the waste liquid, and fewer symbiotic oxides are generated during the high-temperature thermal decomposition process, which finally results in a chromium removal rate lower than 92%, a 1, 2-dichlorobenzene gas conversion rate lower than 87%, and both of them gradually decrease as the molar ratio of the ferrous ions to the calcium ions increases. When the molar ratio of ferrous ions to calcium ions is equal to 1: 3-5, a proper amount of calcium hydroxide ions is added, correspondingly more calcium carbonate, hydroxide precipitates and iron-chromium coprecipitates are generated, trivalent chromium is completely removed, a proper amount of oxide with a symbiotic structure is generated in the high-temperature thermal decomposition process, the chromium removal rate is higher than 96%, the 1, 2-dichlorobenzene gas conversion rate is higher than 90%, and the chromium removal rate and the 1, 2-dichlorobenzene gas conversion rate are gradually increased along with the reduction of the molar ratio of ferrous ions to calcium ions. When the molar ratio of the ferrous ions to the calcium ions is less than 1:5 (as shown in table 3, the molar ratio of the ferrous ions to the calcium ions is 1:5.2, 1:5.5, 1:6 and lower ratios not listed in table 3), the calcium hydroxide ions are added in excess, and the liquid dissolves excessive calcium ions. Calcium ions and carbonate are combined to generate excessive calcium carbonate which covers the surfaces of hydroxide and an iron-chromium precipitation substrate, so that in the high-temperature thermal decomposition process, the calcium carbonate, the hydroxide precipitate and the iron-chromium coprecipitate are not sufficiently decomposed by heating, the output of an oxide in a symbiotic structure is reduced, the performance of the catalyst for removing 1, 2-dichlorobenzene waste gas is influenced finally, the gas conversion rate of 1, 2-dichlorobenzene is lower than 93 percent, and the gas conversion rate is reduced along with the reduction of the molar ratio of ferrous ions to calcium ions. Therefore, in summary, the benefits and the cost are combined, and when the molar ratio of the ferrous ions to the calcium ions is equal to 1: 3-5, the method is most beneficial to improving the chromium removal rate in the waste liquid and improving the catalyst removal performance of the 1, 2-dichlorobenzene waste gas.
Claims (4)
1. The preparation method of the catalyst for removing the waste gas of the 1, 2-dichlorobenzene is characterized by comprising the following steps of: firstly, putting the chromium-containing waste liquid into a sealed container, and aerating carbon dioxide into the container to obtain carbonated chromium-containing waste liquid; then adding ferrous carbonate into the carbonated chromium-containing waste liquid, and stirring under sealed condition to obtain reduced carbonated chromium-containing waste liquid; finally, adding calcium hydroxide into the reduced and carbonated chromium-containing waste liquid, stirring under a sealed condition until a precipitate is generated, carrying out solid-liquid separation, and placing the solid in an atmosphere furnace for thermal decomposition treatment to obtain the 1, 2-dichlorobenzene waste gas removal catalyst;
the unit volume ratio of the carbon dioxide to the chromium-containing waste liquid is 0.5-3: 1; the molar ratio of ferrous ions in the ferrous carbonate to hexavalent chromium ions in the chromium-containing waste liquid is 4-8: 1; the molar ratio of ferrous ions in the ferrous carbonate to calcium ions in the calcium hydroxide is 1: 2-6; the thermal decomposition treatment is carried out for 1-2 h at 900-1000 ℃.
2. The method for preparing a catalyst for removing 1, 2-dichlorobenzene waste gas according to claim 1, wherein the unit volume ratio of the carbon dioxide to the chromium-containing waste liquid is 1-2: 1.
3. The preparation method of the catalyst for removing 1, 2-dichlorobenzene waste gas according to claim 1, wherein the molar ratio of ferrous ions in the ferrous carbonate to hexavalent chromium ions in the chromium-containing waste liquid is 5-7: 1.
4. The method for preparing a catalyst for removing 1, 2-dichlorobenzene waste gas according to claim 1, wherein the molar ratio of ferrous ions in the ferrous carbonate to calcium ions in the calcium hydroxide is 1: 3-5.
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