A two-layer low-temperature catalyst for simultaneous NO and CO removal, its preparation method and application

Abstract

A two-layer low-temperature catalyst for simultaneous NO and CO removal, its preparation method, and its application are disclosed. The catalyst comprises catalyst A, catalyst B, and an intermediate layer. Catalyst A and catalyst B are stacked in a top-to-bottom order, separated by the intermediate layer. Catalyst A is MnCeSmO. x / AC catalyst, catalyst B is CuCeFeO x / AC catalyst, MnCeSmO x The mass ratio of composite oxide to AC support is 6%–11%, CuCeFeO x The mass ratio of the composite oxide to the AC support is 8%–13%. This invention uses modified commercial AC as the support and NH3 and CO as composite reducing agents. Through ingenious catalyst design, it effectively removes NO and CO from sintering flue gas under low-temperature conditions; this can solve the problem of existing NH3... 3‑ SCR catalysts have low denitrification rates under low-temperature conditions, and suffer from problems such as ammonia escape, easy sulfur water poisoning, and difficulty in removing CO. At the same time, they can solve the problem that CO reducing agent CO is easily oxidized and becomes ineffective under oxygen-rich conditions in CO-SCR technology.

Description

Technical Field

[0001] This invention belongs to the field of industrial flue gas purification technology, and specifically relates to a two-layer low-temperature catalyst for simultaneous removal of NO and CO, its preparation method, and its application. Background Technology

[0002] The main air pollutants emitted by steel companies include particulate matter, SO2, and NO. x NO, dioxins, and CO are among the pollutants emitted by steel plants, with the sintering process being the largest source of gaseous pollutants in the industry. NO and CO emissions from the sintering process (accounting for 71% and 46% of total steel plant emissions, respectively) are gradually becoming the most pressing gaseous pollutants for steel companies to control.

[0003] Currently, the treatment of NO and CO pollutants in sintering flue gas mainly employs a staged treatment approach, where each pollutant is treated separately in different systems. While this staged treatment method can effectively remove pollutants, it suffers from drawbacks in practical applications, such as large land area requirements, high construction costs, and complex operating systems. Therefore, coupling the removal of both pollutants into a single reaction system is crucial for the efficient synergistic removal of both pollutants. Given the high oxygen content in sintering flue gas, the rational design of the catalyst becomes key to achieving the synergistic removal of NO and CO from sintering flue gas.

[0004] Existing catalysts use coconut shell AC as a support and CeO2 as the catalyst. x and FeO y The active component is a composite metal oxide. The mass ratio of the active component to coconut shell activated carbon is 3.62–4.73%. Although this catalyst exhibits good denitrification activity at low temperatures under anaerobic conditions, the high O2 content in the sintering flue gas leads to O2 competing with NO for active sites and preferentially inducing the reaction between CO and O2, thus inhibiting the catalyst's CO-SCR activity. Therefore, the application of this catalyst under actual sintering flue gas conditions has certain limitations, and it cannot achieve simultaneous and effective removal of NO and CO.

[0005] On the other hand, the modified carbon-based catalyst comprises 55–75% carbon-based raw materials, 5–15% organic acid precursors, and 15–30% nitrogen-containing compound precursors. While this catalyst exhibits good low-temperature denitrification activity and nitrogen selectivity, its active temperature range is narrow, and ammonia escape is prone to occur during the reaction, leading to secondary pollution. Furthermore, this catalyst is ineffective at removing CO from flue gas, failing to meet the requirements of the steel industry for simultaneously and efficiently removing both NO and CO pollutants from sintering flue gas. Summary of the Invention

[0006] The purpose of this invention is to provide a bilayer low-temperature catalyst for simultaneous removal of NO and CO, its preparation method, and its application, in order to solve the above-mentioned problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A two-layer low-temperature catalyst for simultaneous NO and CO removal includes catalyst A, catalyst B, and an intermediate layer; catalyst A and catalyst B are stacked in a top-to-bottom order, separated by the intermediate layer; catalyst A is MnCeSmO. x / AC catalyst, catalyst B is CuCeFeO x / AC catalyst, MnCeSmO x The mass ratio of composite oxide to AC support is 6%–11%, CuCeFeO x The mass ratio of the composite oxide to the AC support is 8%–13%.

[0009] Furthermore, MnCeSmO x The composite oxide was obtained by mixing manganese nitrate, cerium nitrate, and samarium nitrate in a molar ratio of (5.5–6.25):(2.5–3.25):(0.5–2.0); CuCeFeO x The composite oxide is obtained by mixing copper nitrate, cerium nitrate, and iron nitrate in a molar ratio of (2.75–3.5): (4.5–5.25): (1.25–2.75).

[0010] Furthermore, the AC carrier is commercially available AC activated with 4–5 mol / L nitric acid.

[0011] Furthermore, the middle layer is 1cm thick quartz wool.

[0012] A method for preparing a bilayer low-temperature catalyst for simultaneous removal of NO and CO includes the following steps:

[0013] Obtain activated AC vector;

[0014] Preparation of MnCeSmO x Catalyst active component solution, and CuCeFeO x Catalyst active component solution;

[0015] The activated AC support was added to the prepared MnCeSmO. x Catalyst active component solution, and CuCeFeO x MnCeSmO was obtained from the catalyst active component solution. x / AC catalyst precursor, and CuCeFeO x / AC catalyst precursor;

[0016] To obtain MnCeSmO x / AC catalyst precursor, and CuCeFeO xThe AC catalyst precursor was calcined to obtain MnCeSmO x / AC catalyst, and CuCeFeO x / AC catalyst.

[0017] Further, obtaining the activated AC vector includes:

[0018] AC pretreatment: Commercial activated carbon is added to deionized water for washing, ultrasonically treated for 1-2 hours, solid-liquid separation is performed, and the solid is dried to obtain pretreated activated carbon.

[0019] AC activation: The activated carbon was placed in a 4-5 mol / L nitric acid solution for activation treatment at a temperature of 40-60°C for 3-4 hours. After washing with deionized water several times until the pH reached 7, the activated AC carrier was obtained by drying.

[0020] Furthermore, the preparation of MnCeSmO x Catalyst active component solution, and CuCeFeO x The catalyst active component solution includes:

[0021] MnCeSmO x / AC catalyst active component solution preparation: Manganese nitrate, cerium nitrate, and samarium nitrate were dissolved in deionized water at a molar ratio of (5.5–6.25):(2.5–3.25):(0.5–2.0). The solution was stirred at room temperature for 1–2 hours until it became clear and transparent, yielding MnCeSmO. x A mixed solution of the active components of the AC catalyst;

[0022] CuCeFeO x / AC catalyst active component solution preparation: Copper nitrate, cerium nitrate, and ferric nitrate were dissolved in deionized water at a molar ratio of (2.75–3.5):(4.5–5.25):(1.25–2.75). The solution was stirred at room temperature for 1–2 hours until it became clear and transparent, yielding CuCeFeO. x A mixed solution of the active components of the AC catalyst.

[0023] Furthermore, MnCeSmO was obtained. x / AC catalyst precursor, and CuCeFeO x / AC catalyst precursors include:

[0024] MnCeSmO x / AC catalyst precursor: The obtained activated AC support was impregnated in a mixed solution of active components, ultrasonically treated at 40-60℃ for 1-2 h, followed by solid-liquid separation and drying at 100℃ for 12 h to obtain MnCeSmO x / AC catalyst precursor;

[0025] CuCeFeO x / AC catalyst precursor: The activated AC support is added to the mixed solution of active components in step (4) for impregnation, ultrasonically treated at 40-60℃ for 1-2 h, solid-liquid separation is performed, and dried at 100℃ for 12 h to obtain CuCeFeO x / AC catalyst precursor.

[0026] Furthermore, MnCeSmO was obtained. x / AC catalyst, and CuCeFeO x / AC catalyst:

[0027] MnCeSmO x / AC catalyst calcination: MnCeSmO under N2 as a protective gas condition. x The AC catalyst precursor was calcined in a tube furnace at 450°C for 4 hours to obtain MnCeSmO. x / AC catalyst;

[0028] CuCeFeO x / AC catalyst calcination: CuCeFeO is calcined under N2 as a protective gas. x The AC catalyst precursor was calcined in a tube furnace at 400°C for 5 hours to obtain CuCeFeO. x / AC catalyst.

[0029] Application of a dual-layer low-temperature catalyst for simultaneous NO and CO removal, used for the catalytic removal of NO and CO from sintering flue gas in the steel industry.

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

[0031] This invention uses modified commercial AC as a carrier and NH3 and CO as composite reducing agents. Through ingenious catalyst design, it effectively removes NO and CO from sintering flue gas under low-temperature conditions; this can solve the problem of existing NH3... 3- SCR catalysts have low denitrification rates under low-temperature conditions, and suffer from problems such as ammonia escape, easy sulfur water poisoning, and difficulty in removing CO. At the same time, they can solve the problem that CO-SCR technology is prone to oxidation and failure of the reducing agent CO under oxygen-rich conditions.

[0032] This invention uses modified commercial AC as a carrier and proposes a bilayer low-temperature NO and CO removal catalyst composed of two supported catalysts, A and B, and uses NH3 and CO as composite reducing agents to simultaneously remove NO and CO from sintering flue gas under low-temperature conditions. This can solve the problem of NH3 in existing sintering flue gas denitrification processes. 3- SCR catalysts suffer from problems such as low denitrification rate and susceptibility to sulfur water poisoning under low temperature conditions.

[0033] The double-layer low-temperature NO and CO removal catalyst proposed in this invention not only has a good removal effect on NO in sintering flue gas, but also has a high removal rate on CO in sintering flue gas. When the catalytic temperature is between 150 and 250°C, the removal rates of NO and CO can reach more than 90%.

[0034] This invention uses NH3 and CO as a composite reducing agent instead of the traditional NH3 or CO alone as a reducing gas, which can solve the problems of NH3 escape and environmental pollution, while achieving the purpose of treating waste with waste and saving resources, and saving the cost of flue gas denitrification. Attached Figure Description

[0035] Figure 1 A schematic diagram of the design of a two-layer low-temperature NO and CO removal catalyst;

[0036] Figure 2 The graph shows the NO and CO removal performance of the bilayer low-temperature catalyst prepared in Example 1.

[0037] Figure 3 The graph shows the NO and CO removal performance of the bilayer low-temperature catalyst prepared in Example 2.

[0038] Figure 4 The graph shows the NO and CO removal performance of the bilayer low-temperature catalyst prepared in Example 3.

[0039] Figure 5 The graph shows the NO and CO removal performance of the mixed low-temperature catalyst prepared in Comparative Example 1.

[0040] Figure 6 The graph shows the NO and CO removal performance of the bilayer low-temperature catalyst prepared in Comparative Example 2.

[0041] Figure 7 The graph shows the NO and CO removal performance of the bilayer low-temperature catalyst prepared in Comparative Example 3. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0043] The performance evaluation test of the double-layer low-temperature NO and CO removal catalyst involved in this invention was carried out in a fixed-bed reaction system. The feed gas was mixed and preheated before entering the reactor. The reaction temperature was 75-250℃, the total gas flow rate was 500 ml / min, and the reaction space velocity (GHSV) was 60000 h⁻¹. The simulated sintering flue gas composition was: [NO] = 500 ppm, [CO] = 5000 ppm, [SO₂] = 100 ppm, [O₂] = 11 vol.%, [H₂O] = 10 vol.%, and N₂ was used as the carrier gas. The concentration changes of each gas before and after the reaction were monitored online using a flue gas analyzer.

[0044] The conversion rates of NO and CO removal by the catalyst are calculated using the following formula:

[0045]

[0046] Example 1

[0047] This embodiment discloses a bilayer low-temperature NO and CO removal catalyst, which is composed of supported catalysts A and B. The upper layer is catalyst A, and the lower layer is catalyst B, with a mass ratio of catalyst A to catalyst B of 1:4, separated by a 1 cm thick layer of quartz wool. Catalyst A is MnCeSmO. x / AC catalyst, its support is nitric acid-activated AC, and the active component is MnO. x CeO2 and SmO x A composite metal oxide; catalyst B is CuCeFeO. x / AC catalyst, including nitric acid-activated AC support and CuO x CeO2 and FeO x The active components of the composite metal oxide are formed together.

[0048] The preparation method of the bilayer low-temperature NO and CO removal catalyst is as follows:

[0049] (1) Add AC to deionized water for washing, sonicate at 60°C for 2.5 h, filter, and dry the solid at 100°C for 12 h to obtain pretreated AC.

[0050] (2) The AC pretreated in step (1) was added to a nitric acid solution with a concentration of 4.5 mol / L, activated at 50°C for 5 h, and then washed with deionized water multiple times until the pH was 7. The activated AC carrier was then dried.

[0051] (3) Manganese nitrate, samarium nitrate, and cerium nitrate in a certain molar ratio are dispersed and mixed in water to obtain solution A. The AC carrier activated in step (2) is added to the mixed solution A and impregnated in equal volume. The mixture is ultrasonically treated at 60°C for 2 hours, and the solid and liquid are separated. The solid is dried at 100°C for 12 hours. Under the protection of N2, the solid is heated to 450°C at a heating rate of 10°C / min and calcined for 4 hours to obtain MnCeSmO. x / AC catalyst;

[0052] (4) Copper nitrate, cerium nitrate, and ferric nitrate in a certain molar ratio are dispersed and mixed in water to obtain solution B. The activated AC carrier from step (2) is added to the mixed solution B and impregnated in equal volume. The mixture is ultrasonically treated at 60°C for 2 hours, and the solid and liquid are separated. The solid is dried at 100°C for 12 hours. Under the protection of N2, the solid is heated to 400°C at a heating rate of 10°C / min and calcined for 5 hours to obtain CuCeFeO. x / AC catalyst;

[0053] (5) Add 0.1g MnCeSmO x / AC catalyst was loaded into the upper layer of the quartz reaction tube, and 0.4g CuCeFeO was added. x / AC catalyst is packed into the lower layer of the quartz reaction tube, with 1cm thick quartz wool as a separator.

[0054] The conversion rates of NO and CO of the bilayer low-temperature NO and CO removal catalyst prepared in this embodiment at different temperatures are as follows: Figure 2 As shown in (a), the results show that the catalyst achieves a NO conversion rate of over 90% at 175°C and a CO conversion rate of up to 92% at 200°C. Figure 2 (b) The test results of the catalyst's resistance to H2O and SO2 at 200 °C are presented. The experimental results show that 10 vol.% H2O has only a slight inhibitory effect on the catalyst's denitrification and CO removal activity. When H2O is removed, the conversion rates of both NO and CO can be restored to their initial levels. In a reaction system without H2O, the injection of 100 ppm SO2 significantly reduces the catalyst's NO and CO conversion rates, decreasing to approximately 70% within 3 hours. Notably, with the simultaneous introduction of H2O and SO2, the decrease in CO conversion rate is more pronounced than the decrease in NO removal activity, dropping to approximately 55% within 5 hours.

[0055] Example 2

[0056] This embodiment discloses a bilayer low-temperature NO and CO removal catalyst, which is composed of supported catalysts A and B. The upper layer is catalyst A, and the lower layer is catalyst B, with a mass ratio of catalyst A to catalyst B of 3:2, separated by a 1 cm thick layer of silica wool.x / AC catalyst, its support is nitric acid-activated AC, and the active component is MnO. x CeO2 and SmO x A composite metal oxide; catalyst B is CuCeFeO. x / AC catalyst, including nitric acid-activated AC support and CuO x CeO2 and FeO x The active components of the composite metal oxide are formed together.

[0057] The preparation method of the bilayer low-temperature NO and CO removal catalyst is as follows:

[0058] (1) Add AC to deionized water for washing, sonicate at 60°C for 2.5h, filter, and dry the solid at 100°C for 12h to obtain pretreated activated char.

[0059] (2) The AC pretreated in step (1) was added to a nitric acid solution with a concentration of 4.5 mol / L, activated at 50°C for 5 h, and then washed with deionized water multiple times until the pH was 7. The activated AC carrier was then dried.

[0060] (3) Manganese nitrate, cerium nitrate, and samarium nitrate in a certain molar ratio are dispersed and mixed in water to obtain solution A. The AC carrier activated in step (2) is added to the mixed solution A and impregnated in equal volume. The mixture is ultrasonically treated at 60°C for 2 hours, and the solid and liquid are separated. The solid is dried at 100°C for 12 hours. Under the protection of N2, the solid is heated to 450°C at a heating rate of 10°C / min and calcined for 4 hours to obtain MnCeSmO. x / AC catalyst;

[0061] (4) Copper nitrate, cerium nitrate, and ferric nitrate in a certain molar ratio are dispersed and mixed in water to obtain solution B. The activated AC carrier from step (2) is added to the mixed solution B and impregnated in equal volume. The mixture is ultrasonically treated at 60℃ for 2 hours, and the solid and liquid are separated. The solid is dried at 100℃ for 12 hours. Under the protection of N2, the solid is heated to 400℃ at a heating rate of 10℃ / min and calcined for 5 hours to obtain CuCeFeO. x / AC catalyst;

[0062] 0.3g MnCeSmO x / AC catalyst was loaded into the upper layer of the quartz reaction tube, and 0.2g CuCeFeO was added. x / AC catalyst is packed into the lower layer of the quartz reaction tube, with 1cm thick quartz wool as a separator.

[0063] The conversion rates of NO and CO of the bilayer low-temperature NO and CO removal catalyst prepared in this embodiment at different temperatures are as follows: Figure 3As shown in (a), the results show that the catalyst achieves a NO conversion rate of over 95% at 175°C and a CO conversion rate of up to 100% at 200°C. Figure 3 (b) The test results of the catalyst's resistance to H2O and SO2 at 200℃ are presented. The experimental results show that 10 vol.% H2O has only a slight inhibitory effect on the catalyst's denitrification and CO removal activity. When H2O is removed, the conversion rates of NO and CO can be restored to their initial levels. Injecting 100 ppm SO2 into a reaction system without H2O significantly reduces the catalyst's activity, but the conversion rates of NO and CO remain above 75% for 3 hours. Notably, the simultaneous introduction of H2O and SO2 significantly reduces the CO conversion rate, but the negative impact of SO2 on the catalyst's denitrification activity is partially suppressed. This phenomenon may be due to the reaction of CeO2 components with SO42- in a humid environment. 2- Functionalization increases the number of active sites and acidity on the catalyst surface, thereby partially enhancing the catalyst's resistance to SO2.

[0064] Example 3

[0065] This embodiment discloses a bilayer low-temperature NO and CO removal catalyst, which is composed of supported catalysts A and B. The upper layer is catalyst A, and the lower layer is catalyst B, with a mass ratio of catalyst A to catalyst B of 4:1, separated by a 1 cm thick layer of silica wool. Catalyst A is MnCeSmO. x / AC catalyst, its support is nitric acid-activated activated coke, and the active component is MnO. x CeO2 and SmO x A composite metal oxide; catalyst B is CuCeFeO. x / AC catalyst, including nitric acid-activated AC support and CuO x CeO2 and FeO x The active components of the composite metal oxide are formed together.

[0066] The preparation method of the bilayer low-temperature NO and CO removal catalyst is as follows:

[0067] (1) Add AC to deionized water for washing, sonicate at 60°C for 2.5h, filter, and dry the solid at 100°C for 12h to obtain pretreated activated char.

[0068] (2) The AC pretreated in step (1) was added to a nitric acid solution with a concentration of 4.5 mol / L, activated at 50°C for 5 h, and then washed with deionized water multiple times until the pH was 7. The activated AC carrier was then dried.

[0069] Manganese nitrate, cerium nitrate, and samarium nitrate were dispersed and mixed in water in a certain molar ratio to obtain solution A. The AC carrier activated in step (2) was added to the mixed solution A and impregnated in equal volume. The mixture was ultrasonically treated at 60°C for 2 hours, and the solid and liquid were separated. The solid was dried at 100°C for 12 hours. Under the protection of N2, the solid was heated to 450°C at a heating rate of 10°C / min and calcined for 4 hours to obtain MnCeSmO. x / AC catalyst;

[0070] A solution B is prepared by dispersing and mixing copper nitrate, cerium nitrate and ferric nitrate in water at a certain molar ratio. The AC support activated in step (2) is added to the mixed solution B and impregnated in equal volume. The solution is ultrasonically treated at 60°C for 2 hours, and the solid and liquid are separated. The solid is dried at 100°C for 12 hours. Under the protection of N2, the solid is heated to 400°C at a heating rate of 10°C / min and calcined for 5 hours to obtain CuCeFeOx / AC catalyst.

[0071] 0.40g MnCeSmO x / AC catalyst was loaded into the upper layer of the quartz reaction tube, and 0.10g CuCeFeO was added. x / AC catalyst is packed into the lower layer of the quartz reaction tube, with 1cm thick quartz wool as a separator.

[0072] The conversion rates of NO and CO of the bilayer low-temperature NO and CO removal catalyst prepared in this embodiment at different temperatures are as follows: Figure 4 As shown in (a), the catalyst achieves a NO conversion rate exceeding 95% at 175°C and a CO conversion rate exceeding 90% at 225°C. Figure 4 (b) The test results of the catalyst's resistance to H2O and SO2 at 200 °C are presented. The results show that 10 vol.% H2O has only a slight inhibitory effect on the catalyst's NO and CO removal activity. When H2O is cut off, the conversion rates of both NO and CO can be restored to their initial values. After introducing only 100 ppm SO2, the catalyst activity decreases significantly, with the NO conversion rate decreasing to approximately 70% and the CO conversion rate decreasing to approximately 58% within 3 hours. Notably, when H2O and SO2 are introduced simultaneously, the CO conversion rate decreases significantly, decreasing to approximately 40% within 5 hours, but the negative effect of SO2 on the catalyst's NO removal activity is partially suppressed, and the NO conversion rate remains above 58% within 5 hours.

[0073] The double-layer low-temperature catalyst consists of catalyst A and catalyst B stacked in a specific mass ratio and from top to bottom, separated by a 1cm thick layer of quartz wool. The upper layer is catalyst A, which mainly reacts with NH4+. 3-The SCR reaction removes some NO from the sintering flue gas while consuming O2. The lower layer contains catalyst B, which mainly removes NO and CO from the flue gas through a CO-SCR reaction, while also adsorbing NH4+. 3- NH3 that escapes during the SCR reaction.

[0074] Comparative Example 1

[0075] The preparation methods for catalysts A and B are as described in Example 1. After preparation, 0.3 g of MnCeSmO was added. x / AC catalyst and 0.2g CuCeFeO x The AC catalyst was thoroughly mixed and packed into a quartz reaction tube. Subsequently, the catalyst's NO and CO removal performance was evaluated under the specific test conditions described in Example 1, and the results are shown below. Figure 5 .

[0076] Comparative Example 2

[0077] The preparation methods for catalysts A and B are as described in Example 1. After preparation, 0.2 g of CuCeFeO was added. x / AC catalyst was loaded into the upper layer of the quartz reaction tube, and 0.3g of MnCeSmO was added. x The AC catalyst was loaded into the lower layer of the quartz reaction tube, with a 1 cm thick quartz wool separating the two layers. The catalyst's NO and CO removal performance was then evaluated under the specific test conditions described in Example 1, and the results are shown below. Figure 6 .

[0078] Comparative Example 3

[0079] The preparation methods for catalysts A and B are as described in Example 1. After preparation, 0.3 g of MnCeSmO was added. x / AC catalyst was loaded into the upper layer of the quartz reaction tube, and 0.2g CuCeFeO was added. x The AC catalyst was loaded into the lower layer of the quartz reaction tube, without any quartz wool separating the two layers. Subsequently, the catalyst's NO and CO removal performance was evaluated. Specific performance test conditions were as described in Example 1, and the results are shown below. Figure 7 .

[0080] Catalyst performance evaluation results are as follows Figures 2 to 7 As shown. Figure 2 , Figure 3 and Figure 4 This indicates that the upper layer MnCeSmO x / AC catalyst and lower CuCeFeO xThe mass ratio of the upper to lower catalyst layers affects the removal efficiency of NO and CO from sintering flue gas by the dual-layer low-temperature catalyst. When the mass ratio of the upper to lower catalyst layers is 3:2, the dual-layer low-temperature catalyst exhibits the best removal efficiency of NO and CO from sintering flue gas, as well as optimal resistance to water and sulfur. At 175℃, the NO conversion rate exceeds 95%, and at 200℃, the CO conversion rate reaches 100%. When H2O and SO2 are simultaneously introduced at 200℃, the NO and CO conversion rates of the catalyst remain above 65%. Figure 5 This indicates that the removal efficiency of the mixed low-temperature NO and CO removal catalyst is far inferior to that of the dual-layer low-temperature NO and CO removal catalyst, especially at low temperatures where the NO removal rate is low. Figure 6 and Figure 7 This indicates that MnCeSmO x / AC catalyst and CuCeFeO x The packing order of the AC catalyst and whether or not quartz wool is used as a spacer between the upper and lower catalyst layers both affect the catalyst's removal efficiency of NO and CO from the sintering flue gas. When the upper layer is MnCeSmO... x / AC catalyst, with CuCeFeO as the lower layer. x When using AC catalyst, the double-layer low-temperature catalyst is significantly more effective than the upper catalyst (CuCeFeO) in removing NO and CO from sintering flue gas. x / AC catalyst, with MnCeSmO as the lower catalyst. x The situation with the AC catalyst: When the upper and lower catalyst layers were not separated by a 1cm thick layer of quartz wool, the removal efficiency of NO and CO was slightly inhibited.

[0081] The specific embodiments described above further illustrate the purpose, technical solution, and superior effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A two-layer catalyst for simultaneous removal of NO and CO at low temperature, characterized by, It includes catalyst A, catalyst B, and an intermediate layer; catalyst A and catalyst B are stacked in a top-to-bottom order, separated by an intermediate layer; catalyst A is MnCeSmO x / AC catalyst, catalyst B is CuCeFeO x / AC catalyst, MnCeSmO x The mass ratio of composite oxide to AC support is 6%~11%, CuCeFeO x The mass ratio of composite oxide to AC support is 8%~13%; The intermediate layer is 1 cm thick quartz wool; The AC carrier is a commercial activated coke activated by 4-5 mol / L nitric acid.

2. The catalyst according to claim 1, wherein the catalyst is a catalyst for simultaneous removal of NO and CO at low temperature, and is a catalyst having a double layer structure. MnCeSmO x The composite oxide is obtained by mixing manganese nitrate, cerium nitrate and samarium nitrate in a molar ratio of (5.5-6.25):(2.5-3.25):(0.5-2.0). x The composite oxide is obtained by mixing copper nitrate, cerium nitrate and iron nitrate in a molar ratio of (2.75-3.5):(4.5-5.25):(1.25-2.75).

3. A method for producing the double-layered catalyst for simultaneous removal of NO and CO at low temperature according to any one of claims 1 to 2, characterized by, The method comprises the following steps: obtaining an activated AC carrier; Formulation of MnCeSmO x Catalyst active component solution, as well as CuCeFeO x Catalyst active component solution; The activated AC support was added to the prepared MnCeSmO x catalyst active component solution, and CuCeFeO x catalyst active component solution, and CuCeFeO x / AC catalyst precursor, and CuCeFeO x / AC catalyst precursor; MnCeSmO x / AC catalyst precursor, and CuCeFeO x / AC catalyst precursor were calcined to obtain MnCeSmO x / AC catalyst, and CuCeFeO x / AC catalyst.

4. The method of claim 3, wherein the catalyst is prepared by the steps of: obtaining an activated AC carrier, comprising: AC pretreatment: adding commercial activated coke into deionized water for cleaning, ultrasonic treatment for 1-2 h, solid-liquid separation, and drying the solid to obtain pretreated activated coke; AC activation: placing the pretreated activated coke in a 4-5 mol / L nitric acid solution for activation treatment, activating at a temperature of 40-60 ℃ for 3-4 h, washing with deionized water for multiple times until the pH is 7, and drying to obtain an activated AC carrier.

5. The method of claim 3, wherein the catalyst is prepared by the steps of: Formulating MnCeSmO x Catalyst active component solution, and CuCeFeO x Catalyst active component solution, comprising: MnCeSmO x Catalyst active component solution preparation: Manganese nitrate, cerium nitrate, samarium nitrate were dissolved in deionized water in a molar ratio of (5.5-6.25):(2.5-3.25):(0.5-2.0), stirred at room temperature for 1-2 h until the solution was clear and transparent, to obtain MnCeSmO x Catalyst active component solution; CuCeFeO x Catalyst active component solution preparation: Copper nitrate, cerium nitrate, iron nitrate were dissolved in deionized water in a molar ratio of (2.75-3.5):(4.5-5.25):(1.25-2.75), stirred at room temperature for 1-2 h until the solution was clear and transparent, to obtain CuCeFeO x Catalyst active component solution.

6. The method of claim 3, wherein the catalyst is prepared by the steps of: MnCeSmO x / AC catalyst precursor, and CuCeFeO x / AC catalyst precursor, comprising: MnCeSmO x AC catalyst precursor: the obtained activated AC carrier was added into the MnCeSmO x catalytic active component solution for impregnation, ultrasonic treatment at 40-60℃ for 1-2h, solid-liquid separation, drying at 100℃ for 12h, to obtain MnCeSmO x AC catalyst precursor; CuCeFeO x AC catalyst precursor: the activated AC carrier was added into CuCeFeO x catalytic active component solution, ultrasonic treatment was carried out at 40-60℃ for 1-2h, solid-liquid separation was carried out, and drying was carried out at 100℃ for 12h to obtain CuCeFeO x AC catalyst precursor.

7. The preparation method of the double-layer low-temperature simultaneous NO and CO removal catalyst according to claim 3, characterized in that, MnCeSmO x / AC catalyst, and CuCeFeO x / AC catalyst: MnCeSmO x AC catalyst calcination: MnCeSmO x AC catalyst precursor was placed in a tube furnace and calcined at 450°C for 4h under N2as a protective gas to obtain MnCeSmO x AC catalyst; CuCeFeO x CuCeFeO / AC catalyst calcination: CuCeFeO / AC catalyst precursor was placed in a tube furnace and calcined at 400 °C for 5 h under N2as a protective gas to obtain CuCeFeO / AC catalyst. x CuCeFeO / AC catalyst calcination: CuCeFeO / AC catalyst precursor was placed in a tube furnace and calcined at 400 °C for 5 h under N2as a protective gas to obtain CuCeFeO / AC catalyst. x CuCeFeO / AC catalyst calcination: CuCeFeO / AC catalyst precursor was placed in a tube furnace and calcined at 400 °C 8. Use of the double-layered catalyst for simultaneous removal of NO and CO at low temperature according to any one of claims 1 to 2, characterized in that, The method is used for catalytically removing NO and CO in sintering flue gas in the steel industry.

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