An iron-based catalyst and its preparation method and its application in heterogeneous catalytic oxidation treatment of organic waste gas

Abstract

The present invention relates to an iron-based catalyst, a preparation method thereof, and an application thereof in the treatment of organic waste gas by heterogeneous catalytic oxidation. The iron-based catalyst comprises a MnO2 solid carrier and a catalyst active component loaded in the MnO2 solid carrier; the catalyst active component comprises Ag and Fe. The catalyst active component uses a metal salt solution as a precursor substance and is loaded on a carrier by an impregnation method. The catalyst of the present invention solves the problems existing in the existing commercial iron-based catalysts for heterogeneous catalytic oxidation, such as easy loss of iron ions, easy imbalance of catalyst component ratios, low catalyst activity at room temperature, and easy agglomeration of the catalyst. It can be applied to the scenario of heterogeneous catalytic oxidation treatment of organic waste gas for a long time.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts for heterogeneous catalytic oxidation treatment, and in particular to an iron-based catalyst and a preparation method thereof, and application thereof in heterogeneous catalytic oxidation treatment of organic waste gas. Background Art

[0002] Industrial emissions are the largest source of VOCs, including petrochemicals, coal combustion, coal chemical industry, basic chemical raw material manufacturing, resin synthesis, papermaking and other industries. VOCs emitted into the ambient air can react photochemically with nitrogen oxides in the atmosphere to produce ozone, peroxyacetyl nitrate, aldehydes and other harmful substances, and can also be transformed into secondary organic aerosols, affecting the ambient air quality.

[0003] Heterogeneous catalytic oxidation is an effective technology for VOCs control. This technology effectively degrades VOCs under the combined action of absorption, adsorption, catalysis and oxidation. Among them, the catalyst is the core component of heterogeneous catalytic oxidation technology. Iron is widely used as a catalyst for heterogeneous catalytic oxidation because it is cheap, easy to obtain, widely available, and can catalyze oxidants to produce strong oxidizing free radicals. However, traditional commercial iron-based catalysts have defects such as easy loss of iron ions, easy imbalance of catalyst ratios, low catalyst activity at room temperature, and easy agglomeration of catalysts. These defects will lead to practical industrial application problems such as instability of heterogeneous catalytic oxidation technology for VOCs degradation and short catalyst service life. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, one of the purposes of the present invention is to provide an iron-based catalyst with MnO 2 The invention discloses an iron-based catalyst for treating organic waste gas by using an iron-based catalyst as a carrier, Ag and Fe as active components of the catalyst, and iron ions are not easy to be lost, the catalyst has high activity, and is not easy to be caking; the second purpose of the invention is to provide a method for preparing an iron-based catalyst, in which the active components are loaded on the carrier by an impregnation method, the steps are simple, and the catalyst is suitable for large-scale preparation; the third purpose of the invention is to provide an application of an iron-based catalyst in heterogeneous catalytic oxidation treatment of organic waste gas.

[0005] One of the purposes of the present invention is achieved by the following technical solution:

[0006] An iron-based catalyst, characterized in that the iron-based catalyst comprises MnO 2 Solid support and MnO loaded 2 The active ingredient of the catalyst in the solid support;

[0007] The catalyst active components include Ag and Fe, and the MnO 2 MnO in solid support 2The mass ratio of Fe and Ag is (85-105): (5-8): (1-3); preferably MnO 2 : Fe: Ag=100: (5~8): (1~3).

[0008] The MnO 2 The mass percentage of manganese dioxide in the solid carrier is 85-90%. 2 The specific surface area of ​​the solid carrier is 180-260 mg / m 3 .

[0009] Preferably, it is characterized in that the MnO 2 The shape of the solid carrier is cylindrical or spherical, and the MnO 2 The diameter of the solid carrier is 3 to 8 mm. More preferably, a cylindrical carrier with a diameter of 6 mm is selected.

[0010] The second object of the present invention is achieved by adopting the following technical solution:

[0011] The method for preparing the iron-based catalyst comprises the following steps:

[0012] (1) mixing an iron salt and a silver salt with a solvent to obtain an iron salt and a silver salt mixed solution;

[0013] (2) MnO 2 The solid support is immersed in an acid solution for acidification treatment, washed, and then dried; preferably, the soaking time is 5 to 7 hours, more preferably 6 hours; preferably, after washing with deionized water to neutrality, it is dried at 70 to 90° C. for 12 to 48 hours, more preferably at 80° C. for 24 hours. The pretreatment process of acidifying the support to prepare a Mn-based catalyst can expand the specific surface area of ​​the catalyst, increase the acidic active sites, and the loading amount of the active component on the catalyst.

[0014] (3) The MnO obtained in step (2) 2 The solid carrier is immersed in the mixed solution of iron salt and silver salt obtained in step (1), taken out, dried and calcined to obtain an iron-based catalyst.

[0015] Preferably, the iron salt in step (1) is iron sulfate and / or iron nitrate.

[0016] Preferably, the silver salt in step (1) is silver sulfate and / or silver nitrate; more preferably, the iron salt is Fe(NO 3 ) 3 9H 2 O, silver salt is AgNO 3 .

[0017] Preferably, in the mixed solution of iron salt and silver salt in step (1), the concentration of iron salt is 0.5-0.7 mol / L.

[0018] Preferably, in the mixed solution of iron salt and silver salt in step (1), the concentration of silver salt is 0.04-0.15 mol / L.

[0019] Preferably, the acid solution in step (2) is at least one of citric acid solution, sulfuric acid solution and nitric acid solution; more preferably, the acid solution is nitric acid solution.

[0020] Preferably, the acid solution in step (2) is a citric acid solution, and the mass concentration of the citric acid solution is 5-8%.

[0021] Preferably, the acid solution in step (2) is a sulfuric acid solution, and the mass concentration of the sulfuric acid solution is 4-8%.

[0022] Preferably, the acid solution in step (2) is a nitric acid solution, and the mass concentration of the nitric acid solution is 8-15%.

[0023] Preferably, in step (2), the MnO 2 The mass ratio of the solid carrier to the acid solution is 1:(2-3).

[0024] Preferably, in step (3), the MnO 2 The mass ratio of the solid carrier to the mixed solution of the iron salt and the silver salt is 1:(1.1-1.5).

[0025] Preferably, in step (3), the impregnation is: 2 After the solid carrier is mixed with the mixed solution of the iron salt and the silver salt, magnetic stirring and / or ultrasonic treatment are adopted;

[0026] And / or, the drying temperature in step (3) is 80-100° C.;

[0027] And / or, in the step (3), the calcination temperature is 400-550° C., and the calcination time is 4.5-6 hours.

[0028] The third object of the present invention is achieved by adopting the following technical solution:

[0029] The iron-based catalyst is used in the treatment of organic waste gas by heterogeneous catalytic oxidation.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The iron-based catalyst of the present invention comprises MnO 2 Solid support and MnO loaded 2The catalyst active ingredients in the solid carrier; the catalyst active ingredients include Ag and Fe. The catalyst contains only three ingredients: Mn, Ag and Fe. The doping of the precious metal Ag can accelerate electron transfer in the system, enhance the redox rate of Fe~(2+) / Fe~(3+), and significantly improve the low-temperature activity of the catalyst. The interaction (MMOI) between the precious metal Ag and the metal oxide MnO2 can promote electron transfer, enhance the oxygen migration ability of the catalyst, provide dual active sites between the metal oxide and the precious metal, and enhance the degradation and removal of VOCs. The doping of Ag can maintain the dynamic balance of the valence states of iron and manganese elements in the catalyst system and extend the service life of the catalyst.

[0032] (2) The catalyst of the present invention is prepared by an impregnation method to load the iron salt and the silver salt on the acidified MnO 2 The catalyst is then dried and calcined to obtain a solid catalyst. Different from powder catalysts prepared in conventional laboratories, solid catalysts are not easily lost, are easier to recover and are more suitable for industrial applications.

[0033] (3) The catalyst of the present invention contains Ag and Fe, which can improve the reducibility and oxygen mobility of the catalyst, and can reduce the reaction temperature of the catalytic oxidation of pollutants and improve the degradation efficiency of the catalyst. Therefore, the catalyst is suitable for heterogeneous catalytic oxidation treatment of organic waste gas. DETAILED DESCRIPTION

[0034] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0035] Example 1

[0036] An iron-based catalyst, wherein the iron-based catalyst is MnO 2 As a carrier, Ag and Fe are catalyst active components; the catalyst active components are Fe(NO 3 ) 3 9H 2 O and AgNO 3 As a precursor material. Among them, MnO in the iron-based catalyst 2 MnO in solid support 2 , Fe and Ag in MnO 2 The mass ratio is 100:5.609:1.

[0037] The method for preparing the iron-based catalyst comprises the following steps:

[0038] (1) 43.29 g Fe(NO 3 ) 3 9H 2 O, 1.64gAgNO3 Mix with 200 ml of deionized water to obtain a mixed solution of iron salt and silver salt;

[0039] (2) 112gMnO 2 A cylindrical manganese dioxide carrier with a content of 90% was immersed in a 10% nitric acid solution for 6 hours for acidification, washed with deionized water until neutral, and then dried in a forced air drying oven at 80°C for 24 hours;

[0040] (3) The acidified MnO 2 The carrier is mixed with the prepared mixed solution of iron salt and silver salt, stirred for 8 hours using a magnetic stirrer, and ultrasonically treated for 2 hours to obtain a mixture;

[0041] (4) The obtained mixture was placed in a 100° C. water bath for 6 h and then calcined in a muffle furnace at 400° C. for 5 h to obtain a solid iron-based catalyst.

[0042] Example 2

[0043] An iron-based catalyst, wherein the iron-based catalyst is MnO 2 As a carrier, Ag and Fe are catalyst active components; the catalyst active components are Fe(NO 3 ) 3 9H 2 O and AgNO 3 As a precursor material. Among them, MnO in the iron-based catalyst 2 MnO in solid support 2 , Fe and Ag in MnO 2 The mass ratio is 100:7:2.

[0044] The method for preparing the iron-based catalyst comprises the following steps:

[0045] (1) 50.5 g Fe(NO 3 ) 3 9H 2 O, 3.22gAgNO 3 Mix with 200 ml of deionized water to obtain a mixed solution of iron salt and silver salt;

[0046] (2) 112gMnO 2 A cylindrical manganese dioxide carrier with a content of 90% was immersed in a 7% sulfuric acid solution for 7 hours, washed with deionized water until neutral, and dried in a forced air drying oven at 80°C for 24 hours;

[0047] (3) The pretreated MnO 2 The carrier was mixed with the prepared iron salt and silver salt mixed solution, stirred with a magnetic stirrer for 8 h, and ultrasonically treated for 2 h;

[0048] (4) The obtained mixture was placed in a 100° C. water bath for 6 h and then calcined in a muffle furnace at 400° C. for 5 h to obtain a solid iron-based catalyst.

[0049] Example 3

[0050] An iron-based catalyst, wherein the iron-based catalyst is MnO 2 As a carrier, Ag and Fe are catalyst active components; the catalyst active components are Fe(NO 3 ) 3 9H 2 O and AgNO 3 As a precursor material. Among them, MnO in the iron-based catalyst 2 MnO in solid support 2 , Fe and Ag in MnO 2 The mass ratio is 100:8:3.

[0051] The method for preparing the iron-based catalyst comprises the following steps:

[0052] (1) 28.57gFe 2 (SO 4 ) 3 4.33gAg 2 SO 4 Mix with 200 ml of deionized water to obtain a mixed solution of iron salt and silver salt;

[0053] (2) 112 g of a cylindrical manganese dioxide carrier with a MnO2 content of 90% was immersed in a 6% citric acid solution for 6 h, washed with deionized water until neutral, and then dried in a forced air drying oven at 80° C. for 24 h;

[0054] (3) The pretreated MnO 2 After mixing with the prepared iron salt and silver salt mixed solution, stir with a magnetic stirrer for 8 h and perform ultrasonic treatment for 2 h;

[0055] (4) The obtained mixture was placed in a 100°C water bath for drying for 6 h and then calcined in a muffle furnace at 400°C for 5 h to obtain an iron-based catalyst.

[0056] Example 4

[0057] An iron-based catalyst, wherein the iron-based catalyst is MnO 2 As a carrier, Ag and Fe are catalyst active components; the catalyst active components are Fe(NO 3 ) 3 9H 2 O and AgNO 3 As the precursor material. Among them, Ag and Fe in the catalyst and MnO 2The medium mass ratio is 85:5:1.

[0058] The method for preparing the iron-based catalyst comprises the following steps:

[0059] (1) 42.78 g Fe(NO 3 ) 3 9H 2 O, 1.87gAgNO 3 Mix with 200 ml of deionized water to obtain a mixed solution of iron salt and silver salt;

[0060] (2) 112 g of a cylindrical manganese dioxide carrier with a MnO2 content of 90% was immersed in a 7% sulfuric acid solution for 7 h, washed with deionized water until neutral, and then dried in a forced air drying oven at 80° C. for 24 h;

[0061] (3) mixing the pretreated MnO2 carrier with the prepared iron salt and silver salt mixed solution, stirring with a magnetic stirrer for 8 h, and ultrasonically treating for 2 h;

[0062] (4) The obtained mixture was placed in a 100° C. water bath for 6 h and then calcined in a muffle furnace at 400° C. for 5 h to obtain a solid iron-based catalyst.

[0063] Example 5

[0064] An iron-based catalyst, wherein the iron-based catalyst is MnO 2 As a carrier, Ag and Fe are catalyst active components; the catalyst active components are Fe(NO 3 ) 3 9H 2 O and AgNO 3 The Ag and Fe in the catalyst of Example 5 and MnO 2 Medium quality ratio 105:8:3.

[0065] The method for preparing the iron-based catalyst for heterogeneous catalytic oxidation treatment of organic waste gas comprises the following steps:

[0066] (1) 55.41 gFe(NO 3 ) 3 9H 2 O, 4.53gAgNO 3 Mix with 200 ml of deionized water to obtain a mixed solution of iron salt and silver salt;

[0067] (2) 112 g of a cylindrical manganese dioxide carrier with a MnO2 content of 90% was immersed in a 7% sulfuric acid solution for 7 h, washed with deionized water until neutral, and then dried in a forced air drying oven at 80° C. for 24 h;

[0068] (3) mixing the pretreated MnO2 carrier with the prepared iron salt and silver salt mixed solution, stirring with a magnetic stirrer for 8 h, and ultrasonically treating for 2 h;

[0069] (4) The obtained mixture was placed in a 100° C. water bath for 6 h and then calcined in a muffle furnace at 400° C. for 5 h to obtain a solid iron-based catalyst.

[0070] Comparative Example 1

[0071] The catalyst of Comparative Example 1 is different from that of Example 2 in that: 3 ) 2 Alternative AgNO 3 That is, the mixed solution of iron salt and palladium salt prepared in step (1) of reference document 1 is 47.22gFe(NO 3 ) 3 9H 2 O, 4.06gPd(NO 3 ) 2 The remaining steps are the same as those in Example 2.

[0072] Comparative Example 2

[0073] The catalyst of Comparative Example 2 is different from that of Example 2 in that the carrier of Comparative Example 2 is replaced with 2 The carrier is an equal amount of activated carbon, and the remaining components and steps are the same as those in Example 2.

[0074] Comparative Example 3

[0075] The catalyst of Comparative Example 3 is different from that of Example 2 in that: 2 The support was not subjected to acidification treatment before impregnation. The remaining components and steps were the same as those in Example 2.

[0076] Comparative Example 4

[0077] The iron-based catalyst of Comparative Example 4 is MnO 2 As a carrier, Ag and Fe are catalyst active components; the catalyst active components are Fe(NO 3 ) 3 9H 2 O and AgNO 3 As the precursor material. Among them, Ag and Fe in the catalyst and MnO 2 The medium mass ratio is 80:12:3.

[0078] The method for preparing the iron-based catalyst comprises the following steps:

[0079] (1) 109.08 g Fe(NO3 ) 3 9H 2 O, 5.95gAgNO 3 Mix with 200 ml of deionized water to obtain a mixed solution of iron salt and silver salt;

[0080] (2) 112gMnO 2 A cylindrical manganese dioxide carrier with a content of 90% was immersed in a 7% sulfuric acid solution for 7 hours, washed with deionized water until neutral, and dried in a forced air drying oven at 80°C for 24 hours;

[0081] (3) The pretreated MnO 2 The carrier was mixed with the prepared iron salt and silver salt mixed solution, stirred with a magnetic stirrer for 8 h, and ultrasonically treated for 2 h;

[0082] (4) The obtained mixture was placed in a 100° C. water bath for 6 h and then calcined in a muffle furnace at 400° C. for 5 h to obtain a solid iron-based catalyst.

[0083] Comparative Example 5

[0084] The iron-based catalyst of Comparative Example 5 is MnO 2 As a carrier, Ag and Fe are catalyst active components; the catalyst active components are Fe(NO 3 ) 3 9H 2 O and AgNO 3 As the precursor material. Among them, Ag and Fe in the catalyst and MnO 2 The medium mass ratio is 90:9:1.

[0085] The method for preparing the iron-based catalyst comprises the following steps:

[0086] (1) 72.72 g Fe(NO 3 ) 3 9H 2 O, 1.76gAgNO 3 Mix with 200 ml of deionized water to obtain a mixed solution of iron salt and silver salt;

[0087] (2) 112gMnO 2 A cylindrical manganese dioxide carrier with a content of 90% was immersed in a 7% sulfuric acid solution for 7 hours, washed with deionized water until neutral, and dried in a forced air drying oven at 80°C for 24 hours;

[0088] (3) The pretreated MnO 2 The carrier was mixed with the prepared iron salt and silver salt mixed solution, stirred with a magnetic stirrer for 8 h, and ultrasonically treated for 2 h;

[0089] (4) The obtained mixture was placed in a 100° C. water bath for 6 h and then calcined in a muffle furnace at 400° C. for 5 h to obtain a solid iron-based catalyst.

[0090] Effect Example 1

[0091] The catalyst prepared according to the method of Examples 1 to 3 was placed in a multiphase catalytic oxidation tower for the degradation of waste gas toluene. Toluene and active oxygen entered the oxidation tower from bottom to top, and the spray liquid flowed countercurrently with the waste gas and active oxygen from top to bottom. The waste gas was fully contacted with the spray liquid, catalyst, and active oxygen in the spray tower; the laboratory simulated waste gas air volume was 10 L / min, the residence time was 15 s, the catalytic filler loading was 2.5L, the active oxygen injection amount was 100mg / L·min, and 2L of water with an initial pH of 7 was used as the spray liquid, the liquid-gas ratio was 15L / m3, and a continuous reaction was carried out for 60min, and the toluene inlet concentration was controlled to be 500mg / m 3 The test results are the average removal rate obtained from three experiments. The removal rate calculation formula is as follows, and the results are shown in Table 1:

[0092]

[0093] C0——pollutant concentration at reactor inlet;

[0094] Ct - pollutant concentration at reactor outlet.

[0095] Table 1 Removal rate of catalyst in Examples 1 to 3

[0096]

[0097] As shown in Table 1, Examples 1 to 5 can achieve better toluene removal effects. At this time, the Ag and Fe in the finished product are less than MnO. 2 Mass ratio: MnO 2 :Fe:Ag=(85~105):(5~8):(1~3). Among them, Example 2 is the best example. From Comparative Example 5, it can be seen that when the Fe to Ag loading ratio is too large, the ability of Ag to provide electrons to the carrier and iron is limited, and it is unable to effectively accelerate the redox rate of Fe~(2+) / Fe~(3+) and the oxygen migration ability of the catalyst. From Comparative Example 4, it can be seen that the Fe and Ag in MnO 2 When the load is too high, MnO 2 The active sites of Fe:Ag:MnO are covered, resulting in a decrease in the degradation rate. 2 The optimal ratio is 0.07:0.02:1, at which point the loading amounts of Fe and Ag on MnO2 and the loading ratios of Fe and Ag are both moderate, and the best toluene removal effect can be obtained.

[0098] Effect Example 2

[0099] The catalyst prepared according to the methods of Example 2 and Comparative Example 1 was placed in a multiphase catalytic oxidation tower for the degradation of garbage odor. The mass ratio of metal elements used in the two methods was kept consistent. Garbage odor and active oxygen entered the oxidation tower from bottom to top, and the spray liquid flowed in the opposite direction from the waste gas and active oxygen from top to bottom. The waste gas was fully contacted with the spray liquid, catalyst, and active oxygen in the spray tower; the waste gas air volume was 30L / min, the residence time was 12s, the catalytic filler loading was 5L, the active oxygen injection amount was 100mg / L·min, and 2L of water with an initial pH of 7 was used as the spray liquid, and the liquid-gas ratio was 15L / m 3 , and the continuous reaction was carried out for 60 minutes, and the VOCs inlet concentration was 100-200 mg / m 3 The inlet and outlet concentrations of VOCs are obtained by the VOCs online detector. The removal rate calculation formula is the same as that in Example 1. Each test is carried out continuously for 120 minutes. After the test, the catalyst is simply regenerated. The degradation effect of the catalyst on VOCs after four cycles is shown in Table 2:

[0100] Table 2 Degradation results of Example 2 and Comparative Example 1 and Comparative Example 3

[0101]

[0102] From Table 2, Example 2 and Comparative Example 1, it can be seen that Ag and Pd as noble metals are doped into MnO 2 The catalysts have similar service life, but the removal rate of Ag is better than that of Pd-loaded catalysts. This may be due to the + The ions have a larger ionic radius, and when the loading amount is equivalent, the catalyst surface area increases more than that of the Pd-loaded catalyst. 2 It can achieve better removal rate and stability than untreated MnO 2 This is because acidification can expand the pore volume of the carrier to a certain extent, change the chemical properties of the carrier surface, and make it easier for the active components to be loaded onto the carrier during the impregnation process.

[0103] Effect Example 3

[0104] The catalyst prepared in Example 2 and Comparative Example 2 was placed in a multiphase catalytic oxidation tower, and the device was used to degrade lithium battery waste gas. Lithium battery waste gas and active oxygen enter the oxidation tower from bottom to top, and the spray liquid flows in the opposite direction from top to bottom with the waste gas and active oxygen. The waste gas is fully in contact with the spray liquid, catalyst, and active oxygen in the spray tower. The waste gas air volume is 30L / min, the residence time is 18s, the catalytic filler loading is 7.5L, the active oxygen injection amount is 100mg / L·min, and water with an initial pH of 7 is used as the spray liquid, and the liquid-gas ratio is 20L / m3 , and the continuous reaction lasted for 60 minutes. The VOCs inlet concentration was 800-1200 mg / m 3 The inlet and outlet concentrations of VOCs are obtained by the VOCs online detector. The removal rate calculation formula is the same as that of Example 1. The test results are shown in Table 3:

[0105] Table 3 Removal rate data of Example 2 and Comparative Examples 2 to 3

[0106]

[0107] It can be seen from Table 3 that Example 2 and Comparative Example 2 show that 2 Replacing activated carbon as a carrier can not only improve the activity of the catalyst but also improve the degradation ability of the catalyst. Iron carbon is a common commercial catalyst, but it has the problems of short service life and easy agglomeration of the catalyst, and the catalyst needs to be replaced frequently. 2 There are rich and diverse crystal phases, and the presence of a large number of oxygen vacancies can promote the decomposition of oxidants into active oxygen, which promotes the oxidation of VOCs at low temperatures. In addition, the presence of Ag can promote electron transfer in the system and maintain the carrier MnO 2 The valence state of Mn(2+) / Mn(3+) in the catalyst is improved, thereby extending the service life of the catalyst. 2 The stability of the catalyst with MnO as the carrier is better than that of the catalyst with activated carbon as the carrier. The same effect can be observed in Comparative Example 3. Even though the activity of the catalyst is reduced without acidification, the catalyst with MnO as the carrier is 2 Under the action of Ag ions, the stability of the catalyst is relatively excellent. From Example 2, Comparative Example 2 and Comparative Example 3, it can be seen that MnO 2 The removal rate is not as good as that of the catalyst prepared after nitric acid treatment, as described in Effect Example 2. This is because nitric acid treatment can promote the loading of active components on the carrier surface.

[0108] From the above effect examples, it can be seen that the organic waste gas prepared by the present invention for use in a multi-phase catalytic oxidation reaction tower has an excellent degradation effect on various organic waste gases and can be used for long-term treatment of organic waste gases.

[0109] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. An iron-based catalyst, characterized in that The iron-based catalyst is composed of a MnO2 solid carrier and a catalyst active component loaded in the MnO2 solid carrier; The catalyst active components are Ag and Fe, and the mass ratio of MnO2, Fe and Ag in the MnO2 solid carrier is: MnO2:Fe:Ag=100:(5-8):(1-3); The mass percentage of manganese dioxide in the MnO2 solid carrier is 85-90%, and the specific surface area of ​​the MnO2 solid carrier is 180-260m 2 / g; The shape of the MnO2 solid carrier is cylindrical or spherical, and the diameter of the MnO2 solid carrier is 3 to 8 mm; The MnO2 solid carrier is acidified before loading.

2. The method for preparing the iron-based catalyst according to claim 1, characterized in that: The following steps are involved: (1) mixing an iron salt and a silver salt with a solvent to obtain an iron salt and a silver salt mixed solution; (2) soaking the MnO2 solid carrier in an acid solution for acidification, washing it, and then drying it; (3) The MnO2 solid carrier obtained in step (2) is immersed in the mixed solution of iron salt and silver salt obtained in step (1), taken out, dried, and calcined to obtain an iron-based catalyst.

3. The method for preparing an iron-based catalyst according to claim 2, characterized in that: The iron salt in step (1) is iron sulfate and / or iron nitrate; And / or, the silver salt in step (1) is silver sulfate and / or silver nitrate; And / or, in the mixed solution of iron salt and silver salt in step (1), the concentration of iron salt is 0.5-0.7 mol / L; And / or, in the mixed solution of iron salt and silver salt in step (1), the concentration of silver salt is 0.04-0.15 mol / L.

4. The method for preparing an iron-based catalyst according to claim 2, characterized in that: The acid solution in step (2) is at least one of a citric acid solution, a sulfuric acid solution, and a nitric acid solution; And / or, the acid solution in step (2) is a citric acid solution, and the mass concentration of the citric acid solution is 5-8%; And / or, the acid solution in step (2) is a sulfuric acid solution, and the mass concentration of the sulfuric acid solution is 4-8%; And / or, the acid solution in step (2) is a nitric acid solution, and the mass concentration of the nitric acid solution is 8-15%.

5. The method for preparing an iron-based catalyst according to claim 2, characterized in that: In the step (2), the mass ratio of the MnO2 solid carrier to the acid solution is 1:(2-3).

6. The method for preparing an iron-based catalyst according to claim 2, characterized in that: In the step (3), the mass ratio of the MnO2 solid carrier to the mixed solution of the iron salt and the silver salt is 1:(1.1-1.5).

7. The method for preparing an iron-based catalyst according to claim 2, characterized in that: In the step (3), the impregnation is: mixing the MnO2 solid carrier with a mixed solution of iron salt and silver salt, and then using magnetic stirring and / or ultrasonic treatment; And / or, the drying temperature in step (3) is 80-100° C.; And / or, in the step (3), the calcination temperature is 400-550° C., and the calcination time is 4.5-6 hours.

8. Use of the iron-based catalyst according to claim 1 in the treatment of organic waste gas by heterogeneous catalytic oxidation.

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