Preparation method of low-temperature SCR (Selective Catalytic Reduction) catalyst of coke-loaded transition metal oxide

Abstract

The invention discloses a preparation method of a low-temperature SCR (Selective Catalytic Reduction) catalyst with coke loaded with transition metal oxide. The preparation method comprises the following steps: preparing superfine coal powder; removing mineral substances from the superfine coal powder to obtain ash-removed coal powder; chemically activating the deashed coal powder into an activated coal base; coking the activated coal base to form a coal coke carrier; and preparing a single Fe oxide catalyst and an Fe-Mn composite oxide catalyst which take the coal coke as a carrier. The catalyst is prepared from the coal, so that the utilization value of the coal can be improved, the conversion of the coal from fuel to raw materials can be accelerated, and the pollution of the coal to the environment is reduced. Meanwhile, compared with a noble metal catalyst and coke, the catalyst with the coke carrier prepared by the method disclosed by the invention is lower in price and wide in source, so that the preparation cost of the catalyst can be reduced, and compared with other matrix materials, the coke carrier prepared by the method disclosed by the invention takes superfine pulverized coal coke as a matrix, so that the cost of the catalyst is reduced. The preparation cost is lower, and the pore structure is richer.

Description

Technical Field

[0001] The invention relates to the technical field of air pollution control, and in particular to a method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides. Background Art

[0002] Selective catalytic reduction (SCR) technology refers to the selective catalytic reduction of nitrogen oxides (NO x ) reacts to produce nitrogen and water. The key to the high activity and high selectivity of SCR technology lies in the selection of catalysts. The main choices of catalysts are precious metal catalysts, metal oxide catalysts, molecular sieve catalysts, etc. In recent years, low-cost, high-catalytic efficiency carbon-based material catalysts have gradually developed, and the main representatives are activated carbon, carbon nanotubes and graphene. In addition, coal char materials prepared from coal have also become a hot spot in catalyst research due to their high specific surface area, rich pore structure and a large number of oxygen-containing functional groups. However, compared with other carbon-based materials, coal char structure is too complex, with relatively few active sites, low metal content and uneven distribution. Therefore, it is urgent to further improve the reaction activity of coal char catalysts to promote the development of coal-based carbon materials. Summary of the invention

[0003] In order to solve the above technical problems, the embodiment of the present invention provides a method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides. The specific technical solution is as follows: In order to solve the above-mentioned technical problems, the present invention is achieved as follows: In the first aspect, a method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides is provided, which comprises the following steps: preparing ultrafine coal powder; removing minerals from the ultrafine coal powder to form deashed coal powder; chemically activating the deashed coal powder to form an activated coal base; coking the activated coal base into a coal char carrier; preparing a single Fe oxide catalyst and a Fe-Mn composite oxide catalyst with a coal char carrier.

[0004] In a first possible implementation of the first aspect, in the step of preparing ultrafine coal powder: raw coal lumps are taken and crushed; the crushed raw coal lumps are ultrafinely modified and sieved to obtain ultrafine coal powder.

[0005] In a second possible implementation manner of the first aspect, the average particle size of the ultrafine coal powder is less than 20 μm.

[0006] In a third possible implementation of the first aspect, in the step of removing minerals from the ultrafine coal powder to produce deashed coal powder, a deep acid washing method is used to sequentially deash and depyrite the ultrafine coal powder.

[0007] In a fourth possible implementation of the first aspect, in the step of chemically activating the deashed coal powder into an activated coal base: the deashed coal powder is activated for the first time using K2CO3 or KOH solution; the mixture after the first activation is heated under N2 protection and left for 1 hour for a second activation; impurities in the mixture after the second activation are removed and dried to obtain the mixture after the second activation.

[0008] In a fifth possible implementation of the first aspect, in the step of coking the activated coal base into a coal char carrier, rapid pyrolysis is performed under the protection of an inert gas to produce a coke sample.

[0009] In a sixth possible implementation of the first aspect, in the step of preparing the single Fe oxide catalyst supported by coal char, an excess impregnation method is used to prepare the single Fe oxide catalyst supported by coal char.

[0010] In combination with the sixth possible implementation of the first aspect, in the seventh possible implementation of the first aspect, in the excess impregnation method, the impregnation liquid is selected as FeCl3 solution or Fe(NO)3, and the Fe content is 8%, the impregnation time is 12h, and the drying temperature is 80℃~110℃.

[0011] In an eighth possible implementation of the first aspect, in the step of preparing the Fe—Mn composite oxide catalyst supported by coal char, a citric acid method is used to prepare the Fe—Mn composite oxide catalyst supported by coal char.

[0012] In combination with the eighth possible implementation of the first aspect, in a ninth possible implementation of the first aspect, in the citric acid method, a citric acid complex is first prepared by using manganese acetate, ferric nitrate and citric acid solution, and then a coal char carrier is added to the citric acid complex, heated and stirred in a water bath, and finally dried and calcined.

[0013] In the embodiment of the present invention, the catalyst is prepared by coal, which can not only improve the utilization value of coal, but also accelerate the transformation of coal from fuel to raw material, and reduce its pollution to the environment. At the same time, compared with precious metal catalysts, the coal char carrier prepared by the method of the present invention is cheaper and has a wide source, which can reduce the cost of catalyst preparation. Compared with other matrix materials (such as porous activated carbon and porous molecular sieves), the coal char carrier prepared by the present invention uses ultrafine coal powder char as the matrix, has lower preparation cost and richer pore structure, and further enriches the application of carbon materials.

[0014] At the same time, the preparation method of the present invention also introduces oxides of transition metals Fe and Mn as active substances, which further improves the low-temperature activity of the catalyst. Compared with the catalyst with Fe oxide as a single component, the carbon-based material-loaded iron oxide catalyst has higher activity and N2 selectivity, and better resistance to SO2 and H2O poisoning. Due to the synergistic effect between metal elements, the activity of composite metal oxide catalysts is considered to be better than that of single metal component catalysts. When the carbon-based material is composite-loaded with Fe and Mn metal oxides, the catalyst will show better low-temperature denitrification activity in the NH3-SCR reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 It is a flowchart of the execution sequence of a method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides according to an embodiment of the present invention; Figure 2 The present invention is a flowchart of the steps of a method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides according to an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] In addition, the terms “first”, “second”, etc. used in this document do not specifically refer to an order or sequence, nor are they used to limit the present invention. They are merely used to distinguish components or operations described with the same technical terms.

[0018] See also Figure 1 and Figure 2, which is an execution sequence block diagram and step flow chart of a method for preparing a low-temperature SCR catalyst of a transition metal oxide loaded on coal char according to an embodiment of the present invention; as shown in the figure, the method for preparing a low-temperature SCR catalyst of a transition metal oxide loaded on coal char according to this embodiment includes the following steps S1 to S5. First, ultrafine coal powder is prepared in step S1. Take the raw coal block and crush it, then the crushed raw coal block is ultrafinely modified and sieved to obtain ultrafine coal powder. After the raw coal block is ultrafine, not only can its combustion characteristics be significantly improved, but also it has the advantages of good stable combustion effect, high combustion efficiency, low NOx emission, and high comprehensive economy, and its ultrafine particles have a more developed pore structure, increased specific surface area and porosity, which can accelerate the heat and mass transfer process, provide more reactive sites, and also make the minerals in the coal have a greater degree of dissociation. These characteristics are all conducive to making up for the defects of coal-based catalysts in reaction activity, and also have cost advantages. In this embodiment, the crushed raw coal lumps can be subjected to ultrafine modification in a mechanochemical modification device, and the average particle size of the ultrafine coal powder obtained by screening is less than 20 μm.

[0019] As mentioned above, if only the ultrafine coal powder prepared in step S1 is used as a catalyst, its denitrification efficiency is often low. In order to improve the catalytic effect of the carbon material, in step S2, the ultrafine coal powder is demineralized to become deashed coal powder in this embodiment to reduce the influence of other metal impurities on the reduction reaction and improve the activity of the coal char carrier prepared subsequently. In this embodiment, the ultrafine coal powder is deashed and depyrite treated in sequence by a deep acid washing method. Specifically, the ultrafine coal powder can be deashed by a hydrochloric acid-hydrofluoric acid-hydrochloric acid method, and the deashed ultrafine coal powder is depyrite removed by a nitric acid deep acid washing method.

[0020] In order to achieve the coordinated development of the pore structure and graphitization degree of the coal sample, so that the prepared activated coal base can show excellent performance in the subsequent SCR reaction and run more stably, the deashed coal powder is chemically activated into an activated coal base in step S3. In this embodiment, the deashed coal powder is first activated by K2CO3 or KOH solution for the first time, and then the mixture after the first activation is heated under the protection of N2 gas, and stays for 1 hour for the second activation, and finally the impurities in the mixture after the second activation are removed by dilute hydrochloric acid solution and deionized water, and dried to obtain the mixture after the second activation, so as to obtain the activated coal base.

[0021] Then in step S4, the activated coal base is coked into a coal char carrier. Coking can be carried out on a fixed bed in the laboratory, and rapid pyrolysis is carried out under an inert gas (such as N2) to prepare a coke sample. Since metal loading has been widely used in the modification of carbon-based materials, the catalytic activity of carbon-based materials can be improved by adding different active components, and the SCR denitrification effect can be improved. Therefore, in step S5, a single Fe oxide catalyst and a Fe-Mn composite oxide catalyst with a coal char carrier are prepared. In this embodiment, an excess impregnation method is used to prepare a single Fe oxide catalyst with a coal char carrier, wherein the impregnation liquid is selected from FeCl3 solution or Fe(NO)3, and the Fe content is 8%, the impregnation time is 12h, and the drying temperature is 80℃~110℃.

[0022] As mentioned above, the Fe-Mn composite oxide catalyst with coal char carrier is prepared by citric acid method. In the citric acid method, a citric acid complex is first prepared by manganese acetate, ferric nitrate and citric acid solution, wherein the manganese acetate and ferric nitrate contain 4% Fe and Mn, and the citric acid solution is 2 mol / L, and then the coal char carrier is added to the citric acid complex, and heated and stirred in a water bath, and finally dried and roasted, wherein the water bath heating temperature is 70°C, the roasting temperature can be selected from 400 to 600°C, and the time is 5h.

[0023] The method for preparing a low-temperature SCR catalyst of transition metal oxides loaded with coal char in this embodiment firstly ultrafines the raw coal block, then removes the minerals (deep pickling) and activates it to prepare a coal char carrier, and finally uses the coal char carrier to prepare a single Fe oxide catalyst and a Fe-Mn composite oxide catalyst, which can not only improve the utilization value of coal, but also accelerate the transformation of coal from fuel to raw material, and reduce its pollution to the environment. At the same time, compared with precious metal catalysts, the coal char carrier prepared by the method of the present invention has a lower price and a wide source, which can reduce the cost of catalyst preparation. Compared with other matrix materials (such as porous activated carbon and porous molecular sieves), the coal char carrier prepared by the present invention uses ultrafine coal powder char as the matrix, has a lower preparation cost and a richer pore structure, and further enriches the application of carbon materials.

[0024] At the same time, the preparation method of this embodiment also introduces oxides of transition metals Fe and Mn as active substances, which further improves the low-temperature activity of the catalyst. Compared with the catalyst with Fe oxide as the single component, the carbon-based material-loaded iron oxide catalyst has higher activity and N2 selectivity, and better resistance to SO2 and H2O poisoning. Due to the synergistic effect between metal elements, the activity of composite metal oxide catalysts is considered to be better than that of single metal component catalysts. When the carbon-based material is composite-loaded with Fe and Mn metal oxides, the catalyst will show better low-temperature denitrification activity in the NH3-SCR reaction. The beneficial effects of the method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides according to the present invention will be described below with specific examples.

[0025] Example 1 Step (1) Start with the preparation of ultra-fine coal powder, put the crushed coal powder into a ball mill or a jet mill for grinding, keep the environmental conditions and working conditions consistent during the sample preparation process, and extend the grinding time as much as possible. The ultra-fine coal powder is sieved with a metal standard sieve on the laboratory's XSB-70B standard vibrating screen machine, and the coal sample with an average particle size of less than 20 μm is selected for coking.

[0026] Step (2) Demineralize the coal sample by deep pickling. Weigh 6 g of coal sample, add 1-2 ml of ethanol to wet the coal sample, then slowly add 40 ml of hydrochloric acid (mixed with 36% hydrochloric acid and deionized water in a volume ratio of 1:1), place in a constant temperature water bath at 55-60°C and stir every 5-10 minutes. After 45-50 minutes, filter the coal sample and transfer it to a plastic beaker; add 40 ml of hydrofluoric acid (40% by mass), mix, soak, stir, and filter with the original filter paper; then slowly add 50 ml of hydrochloric acid, mix, soak, stir, and filter with the original filter paper; place the coal sample and the filter paper in a drying oven and dry at 110°C for 24 hours for later use. Pyrite is removed by HNO3 pickling. Use 100 ml of 15% nitric acid solution to add 5 g of coal and heat in a water bath at 80°C for 6 hours. Finally, wash with deionized water several times to obtain a demineralized coal sample.

[0027] Step (3) The demineralized coal char and K2CO3 are uniformly mixed in a mass ratio of 1:3, and the resulting mixture is heated to 1200°C in a 200mL / min N2 atmosphere, held for 1 hour, and then cooled to room temperature; impurities are removed by 2mol / L dilute hydrochloric acid solution and deionized water, and the mixture is dried.

[0028] Step (4) Coking is carried out on a fixed bed in the laboratory. Before starting coking, high-purity N2 is introduced for a period of time to ensure that the char preparation process is carried out in a completely inert atmosphere. During the char preparation process, rapid pyrolysis is carried out in an inert atmosphere (N2) to obtain a char sample, thereby obtaining a catalyst carrier.

[0029] Step (5) Add 50 mL of FeCl3 solution with an iron content of 8% to 5 g of demineralized coal sample, soak for 12 h, filter, wash with deionized water until no chloride ions are detected, and vacuum dry at 80°C to obtain a single Fe oxide catalyst with coal char as the carrier.

[0030] Step (6) The single Fe oxide catalyst for low-temperature SCR denitration prepared in this embodiment is placed in a fixed bed quartz tube reactor and the activity test is carried out in a temperature range of 100-300°C. The total gas flow rate in the reaction is about 500mL / min, and the gas introduced includes NO concentration of 500ppm, NH3 concentration of 500ppm, and 3%vol O2. The concentration of NOx is measured by an electrochemical gas analyzer. The result of the denitration performance test is: NO conversion rate ≥80%.

[0031] Example 2 Step (1) The coal powder is ultra-finely modified and screened in the same manner, and the coal sample is demineralized by deep acid washing.

[0032] Step (2) The demineralized coal char and KOH are uniformly mixed in a mass ratio of 1:5, and the dried powder is heated at 800°C in a N2 atmosphere for 1 hour for activation, and the remaining KOH is neutralized with a 2 mol / L dilute hydrochloric acid solution, and then the solution is washed with deionized water until it is neutral and dried.

[0033] Step (3) Coking is performed on a fixed bed in the laboratory to obtain a catalyst carrier. 50 mL of FeCl3 solution with an iron content of 8% is added to 5 g of demineralized coal sample, and the mixture is filtered after soaking for 12 h, and washed with deionized water until no chloride ions are detected. After vacuum drying at 80°C, a single Fe oxide catalyst with coal coke as the carrier is obtained.

[0034] Step (4) The single Fe oxide catalyst for low-temperature SCR denitration prepared in this embodiment is placed in a fixed bed quartz tube reactor and the activity test is carried out in a temperature range of 100-300°C. The total gas flow rate in the reaction is about 500mL / min, and the gas introduced includes NO concentration of 500ppm, NH3 concentration of 500ppm, and 3%vol O2. The concentration of NOx is measured by an electrochemical gas analyzer. The result of the denitration performance test is: NO conversion rate ≥80%.

[0035] Example 3 Step (1) The coal powder is ultra-finely modified and screened in the same manner, and the coal sample is demineralized by deep acid washing.

[0036] Step (2) The demineralized coal char and K2CO3 are uniformly mixed in a mass ratio of 1:3, and the resulting mixture is heated to 1200°C in a 200mL / min N2 atmosphere, kept for 1 hour, and then cooled to room temperature; impurities are removed by 2mol / L dilute hydrochloric acid solution and deionized water, and the mixture is dried.

[0037] Step (3) Coking is performed on a fixed bed in the laboratory to obtain a catalyst carrier. 50 mL of Fe(NO)3 solution with an iron content of 8% is added to 5 g of demineralized coal coke sample, and after immersion for 12 h, it is vacuum dried at 110°C for 12 h, and then heated at 350°C for 2 h to decompose nitrates, and then cooled in N2 to obtain a single Fe oxide catalyst with coal coke as the carrier.

[0038] Step (4) The single Fe oxide catalyst for low-temperature SCR denitration prepared in this embodiment is placed in a fixed bed quartz tube reactor and the activity test is carried out in a temperature range of 100-300°C. The total gas flow rate in the reaction is about 500mL / min, and the gas introduced includes NO concentration of 500ppm, NH3 concentration of 500ppm, and 3%vol O2. The concentration of NOx is measured by an electrochemical gas analyzer. The result of the denitration performance test is: NO conversion rate ≥80%.

[0039] Example 4 Step (1) The coal powder is ultra-finely modified and screened in the same manner, and the coal sample is demineralized by deep acid washing.

[0040] Step (2) The demineralized coal char and KOH are uniformly mixed in a mass ratio of 1:5, and the dried powder is heated at 800°C in a N2 atmosphere for 1 hour for activation, and the remaining KOH is neutralized with a 2 mol / L dilute hydrochloric acid solution, and then the solution is washed with deionized water until it is neutral and dried.

[0041] Step (3) Coking is performed on a fixed bed in the laboratory to obtain a catalyst carrier. 50 mL of Fe(NO)3 solution with an iron content of 8% is added to 5 g of demineralized coal coke sample, and the mixture is immersed for 12 h and then vacuum dried at 110°C for 12 h, and then heated at 350°C for 2 h to decompose nitrates, and finally cooled in N2 to obtain a single Fe oxide catalyst with coal coke as the carrier.

[0042] Step (4) The single Fe oxide catalyst for low-temperature SCR denitration prepared in this embodiment is placed in a fixed bed quartz tube reactor and the activity test is carried out in a temperature range of 100-300°C. The total gas flow rate in the reaction is about 500mL / min, and the gas introduced includes NO concentration of 500ppm, NH3 concentration of 500ppm, and 3%vol O2. The concentration of NOx is measured by an electrochemical gas analyzer. The result of the denitration performance test is: NO conversion rate ≥80%.

[0043] Example 5 Step (1) The coal powder is ultra-finely modified and screened in the same manner, and the coal sample is demineralized by deep acid washing.

[0044] Step (2) The demineralized coal char and K2CO3 are uniformly mixed in a mass ratio of 1:3, and the resulting mixture is heated to 1200°C in a 200mL / min N2 atmosphere, kept for 1 hour, and then cooled to room temperature; impurities are removed by 2mol / L dilute hydrochloric acid solution and deionized water, and the mixture is dried.

[0045] Step (3) Coking is performed on a fixed bed in the laboratory to obtain a catalyst carrier. A certain amount of manganese acetate and ferric nitrate are weighed and placed in a beaker (containing 4% of Fe and Mn), and a certain amount of citric acid solution (2 mol / L, the same as the molar number of the metal) is added. Stirring is performed at room temperature for 2 hours to form a stable citric acid complex, and then a certain amount of coal coke carrier is added. The mixture is placed in a 70°C water bath and stirred continuously until the water in the mixture is evaporated. The mixture is then dried at a constant temperature of 110°C for 12 hours, and then calcined at 600°C for 5 hours to obtain the desired Fe-Mn composite oxide catalyst.

[0046] Step (4) The Fe-Mn composite oxide catalyst for low-temperature SCR denitration prepared in this embodiment is placed in a fixed bed quartz tube reactor and an activity test is performed in a temperature range of 100-300°C. The total gas flow rate in the reaction is about 500 mL / min, and the gas introduced includes NO concentration of 500 ppm, NH3 concentration of 500 ppm, and 3% vol O2. The NOx concentration is measured by an electrochemical gas analyzer. The result of the denitration performance test is: NO conversion rate ≥ 90%.

[0047] Example 6 Step (1) The coal powder is ultra-finely modified and screened in the same manner, and the coal sample is demineralized by deep acid washing.

[0048] Step (2) The demineralized coal char and KOH are uniformly mixed in a mass ratio of 1:5, and the dried powder is heated at 800°C in a N2 atmosphere for 1 hour for activation, and the remaining KOH is neutralized with a 2 mol / L dilute hydrochloric acid solution, and then the solution is washed with deionized water until it is neutral and dried.

[0049] Step (3) Coking is performed on a fixed bed in the laboratory to obtain a catalyst carrier. A certain amount of manganese acetate and ferric nitrate are weighed and placed in a beaker (containing 4% of Fe and Mn), and a certain amount of citric acid solution (2 mol / L, the same as the molar number of the metal) is added. Stirring is performed at room temperature for 2 hours to form a stable citric acid complex, and then a certain amount of coal coke carrier is added. The mixture is placed in a 70°C water bath and stirred continuously until the water in the mixture is evaporated. The mixture is then dried at a constant temperature of 110°C for 12 hours, and then calcined at 600°C for 5 hours to obtain the desired Fe-Mn composite oxide catalyst.

[0050] Step (4) The Fe-Mn composite oxide catalyst for low-temperature SCR denitration prepared in this embodiment is placed in a fixed bed quartz tube reactor and an activity test is performed in a temperature range of 100-300°C. The total gas flow rate in the reaction is about 500mL / min, and the gas introduced includes NO concentration of 500ppm, NH3 concentration of 500ppm, and 3%vol O2. The NOx concentration is measured by an electrochemical gas analyzer. The result of the denitration performance test is: NO conversion rate ≥90%.

[0051] In summary, the present invention provides a method for preparing a low-temperature SCR catalyst of transition metal oxides loaded with coal char. The present invention prepares the catalyst from coal, which can not only improve the utilization value of coal, but also accelerate the transformation of coal from fuel to raw material, and reduce its pollution to the environment. At the same time, compared with precious metal catalysts, the coal char carrier prepared by the method of the present invention is cheaper and has a wide source, which can reduce the cost of catalyst preparation. Compared with other matrix materials (such as porous activated carbon, porous molecular sieve), the coal char carrier prepared by the present invention uses ultrafine coal powder and coal char as the matrix, which has a lower preparation cost and a richer pore structure, further enriching the application of carbon materials.

[0052] At the same time, the preparation method of the present invention also introduces oxides of transition metals Fe and Mn as active substances, which further improves the low-temperature activity of the catalyst. Compared with the catalyst with Fe oxide as a single component, the carbon-based material-loaded iron oxide catalyst has higher activity and N2 selectivity, and better resistance to SO2 and H2O poisoning. Due to the synergistic effect between metal elements, the activity of composite metal oxide catalysts is considered to be better than that of single metal component catalysts. When the carbon-based material is composite-loaded with Fe and Mn metal oxides, the catalyst will show better low-temperature denitrification activity in the NH3-SCR reaction.

[0053] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0054] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides, characterized in that: The following steps are involved: Preparation of ultrafine coal powder; Demineralizing the ultrafine coal powder to produce deashed coal powder; Chemically activating the deashed coal powder into an activated coal base; Coking the activated coal base into a coal char carrier; A single Fe oxide catalyst and a Fe-Mn composite oxide catalyst using the coal char as a carrier are prepared.

2. The method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides according to claim 1, characterized in that: In the step of preparing the ultrafine coal powder: Take the raw coal lumps and break them; The crushed raw coal lumps are subjected to ultra-fine modification and screening to obtain the ultra-fine coal powder.

3. The method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides according to claim 1, characterized in that: The average particle size of the ultrafine coal powder is less than 20 μm.

4. The method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides according to claim 1, characterized in that: In the step of removing minerals from the ultrafine coal powder to obtain the deashed coal powder, a deep acid washing method is used to sequentially deash and depyrite the ultrafine coal powder.

5. The method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides according to claim 1, characterized in that: The step of chemically activating the deashed coal powder into the activated coal base: Activating the deashed coal powder for the first time using K2CO3 or KOH solution; The mixture after the first activation was heated under N2 protection and kept for 1 h for the second activation; The impurities in the mixture after the second activation are removed, and the mixture is dried to obtain a mixture after the second activation.

6. The method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides according to claim 1, characterized in that: In the step of coking the activated coal base into the coal char carrier, rapid pyrolysis is carried out under the protection of inert gas to prepare a coke sample.

7. The method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides according to claim 1, characterized in that: In the step of preparing the single Fe oxide catalyst supported by the coal char, an excess impregnation method is used to prepare the single Fe oxide catalyst supported by the coal char.

8. The method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides according to claim 7, characterized in that: In the excess impregnation method, the impregnation liquid is FeCl3 solution or Fe(NO)3, and the Fe content is 8%, the impregnation time is 12h, and the drying temperature is 80℃~110℃.

9. The method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides according to claim 1, characterized in that: In the step of preparing the Fe-Mn composite oxide catalyst supported by the coal char, a citric acid method is used to prepare the Fe-Mn composite oxide catalyst supported by the coal char.

10. The method for preparing a low-temperature SCR catalyst of coal char loaded with transition metal oxides according to claim 9, characterized in that: In the citric acid method, a citric acid complex is first prepared by using manganese acetate, ferric nitrate and citric acid solution, and then the coal char carrier is added to the citric acid complex, heated and stirred in a water bath, and finally dried and calcined.

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