Nitrogen oxide removal catalyst for resisting PbCl2 poisoning as well as preparation method and application of nitrogen oxide removal catalyst

Abstract

The invention relates to a PbCl2 poisoning-resistant nitrogen oxide removal catalyst as well as a preparation method and application thereof, and belongs to the technical field of flue gas purification. A carrier of the catalyst is double-activated coconut shell activated carbon, active components are iron oxides and / or cerium oxides, the iron oxides are FeO and Fe2O3, the cerium oxides are Ce2O3 and CeO2, and the total content of metal elements in the active components is 5-9% of the mass of the coconut shell activated carbon. The preparation method comprises the following steps: sequentially carrying out high-temperature gas activation and nitric acid activation treatment on coconut shell activated carbon to obtain a double-activated coconut shell activated carbon carrier, adding the double-activated coconut shell activated carbon carrier into an active metal nitrate solution, carrying out ultrasonic impregnation to obtain a catalyst precursor, and mixing and roasting the catalyst precursor and P2O5 powder to obtain the PbCl2 poisoning resistant nitrogen oxide removal catalyst. The catalyst disclosed by the invention has extremely high PbCl2 poisoning resistance and relatively high removal efficiency in the application of removing nitrogen oxides, and is excellent in N2 selectivity, environment-friendly and pollution-free.

Description

Technical Field

[0001] This invention relates to a nitrogen oxide removal catalyst resistant to PbCl2 poisoning, its preparation method and application, belonging to the field of flue gas purification technology. Background Technology

[0002] Currently removing NO x The technology suffers from problems such as a narrow temperature window, high cost, and failure to meet national ultra-low emission requirements for purification. In addition, the sintering flue gas contains a large amount of dust and heavy metals that clog the catalyst pores. Among them, Pb, as a toxic heavy metal, combines with the toxic Cl2 gas in the flue gas to form PbCl2, which has a serious toxic effect on the SCR catalyst. Summary of the Invention

[0003] Targeting the removal of NO x The catalyst is susceptible to PbCl2 poisoning during the catalytic removal of nitrogen oxides from flue gas. This invention proposes a PbCl2-resistant catalyst for nitrogen oxide removal, its preparation method, and its application. Coconut shell activated carbon is sequentially activated by high-temperature gas and then by nitric acid to obtain a double-activated coconut shell activated carbon support. This double-activated coconut shell activated carbon support is then ultrasonically impregnated in an active metal nitrate solution to obtain a catalyst precursor. The catalyst precursor is mixed with P2O5 powder and calcined to obtain a PbCl2-resistant nitrogen oxide removal catalyst. This catalyst exhibits strong resistance to PbCl2 poisoning and high removal efficiency in nitrogen oxide removal applications. It also demonstrates excellent N2 selectivity and is environmentally friendly and pollution-free. It can simultaneously solve the technical problems of low nitrogen oxide removal efficiency, easy pore blockage, easy poisoning, and short lifespan of existing SCR process catalysts in flue gas denitrification.

[0004] A nitrogen oxide removal catalyst resistant to PbCl2 poisoning, wherein the support is dual-activated coconut shell activated carbon, and the active components are iron oxides and / or cerium oxides, wherein the iron oxides are FeO and Fe2O3, and the cerium oxides are Ce2O3 and CeO2, and the total content of metal elements in the active components is 5-9% of the mass of coconut shell activated carbon; when the active components are iron oxides and cerium oxides, the mass ratio of Fe to Ce elements in the active components is 1:1.

[0005] The preparation method of the PbCl2-resistant nitrogen oxide removal catalyst includes the following specific steps: (1) Add coconut shell activated carbon to deionized water, ultrasonically clean it at a temperature of 60~85℃, separate the solid and liquid, and dry it to obtain clean coconut shell activated carbon. (2) Air is introduced into the clean coconut shell activated carbon and activated at 800~1050℃ for 4~6.5h. After cooling to room temperature, a first-stage activated coconut shell activated carbon is obtained. The first-stage activated coconut shell activated carbon is added to a nitric acid solution for activation treatment and washed with deionized water to obtain a double-activated coconut shell activated carbon carrier. (3) Add the dual-activated coconut shell activated carbon carrier to the active metal nitrate solution, add citric acid and mix evenly, then add an alkaline agent until the pH is 6~8.5, ultrasonically impregnate, evaporate the solvent, and dry to obtain the dual-activated coconut shell activated carbon catalyst precursor. (4) The double-activated coconut shell activated carbon catalyst precursor was mixed evenly with P2O5 powder and placed under a protective atmosphere and calcined at 450~700℃ for 4~6.5h to obtain a nitrogen oxide removal catalyst resistant to PbCl2 poisoning.

[0006] Preferably, the air introduction rate in step (2) is 700~1200 ml / min.

[0007] Preferably, in step (2), the concentration of the nitric acid solution is 4~6.5 mol / L, the activation temperature is 80~105℃, and the activation time is 2~4.5h.

[0008] Preferably, in step (3), the active metal nitrate is Fe(NO3)3·9H2O and / or Ce(NO3)2·6H2O, the total concentration of metal salt in the active metal nitrate solution is 0.4~0.9mol / L, the amount of citric acid added is 2~4.5ml / L, and the alkaline agent is sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonia (NH3·H2O), sodium bicarbonate (NaHCO3) or sodium carbonate (Na2CO3).

[0009] More preferably, the ultrasonic impregnation temperature is 80~105℃, the impregnation time is 1~3.5h, and the evaporation temperature is 100~150℃.

[0010] Preferably, in step (5), the mass ratio of P2O5 powder to the dual-activated coconut shell activated carbon catalyst precursor is 5~10:100.

[0011] Preferably, the protective gas in step (5) is nitrogen or an inert gas.

[0012] The PbCl2-resistant nitrogen oxide removal catalyst is used as a catalyst in the removal of nitrogen oxides: NH3 and CO are used as reducing agents, and the catalytic temperature is 100~250℃.

[0013] This invention uses nitric acid-activated carbon as a carrier, which can significantly increase the number of oxygen-containing functional groups on the surface of activated carbon. High-temperature physical activation can increase the specific surface area of ​​the catalyst and improve the internal pore volume and pore size of the activated carbon catalyst. Ultrasonic impregnation can effectively help the active metal elements to be uniformly dispersed on the catalyst surface and ensure the success rate of loading, thereby ensuring that the catalyst is not prone to agglomeration and has excellent denitrification activity. The dual-activated coconut shell activated carbon catalyst precursor is mixed with P2O5 powder and calcined at high temperature. The high temperature of P2O5 reactivates the pore structure of activated carbon, increases the specific surface area and porosity parameters, and converts the successfully loaded active metal elements into oxides, thereby improving the catalyst's resistance to PbCl2 poisoning.

[0014] The principle behind the catalyst's resistance to PbCl2 poisoning during nitrogen oxide removal is as follows: PbCl2 loaded on the catalyst surface undergoes severe aggregation, disrupting the catalyst's pore structure and reducing the number of oxygen-containing functional groups, oxygen vacancies, and acidic sites on the catalyst surface. This generates pseudo-acidic sites, preventing the reducing gas from activating and participating in the reaction, thus reducing gas-to-gas interactions, inhibiting the rapid SCR reaction, and ultimately lowering the catalyst's denitrification efficiency. The method of this invention can significantly improve the catalyst surface porosity parameters, especially through strong interactions arising from bimetallic synergistic loading, which further increases the number of functional groups and acidic sites, thereby enhancing resistance to PbCl2 poisoning.

[0015] The beneficial effects of this invention are: (1) The catalyst of this invention uses inexpensive coconut shell activated carbon as a carrier. After high-temperature gas activation and nitric acid chemical activation, it is ultrasonically impregnated with active metal and then mixed with P2O5 powder and calcined at high temperature. This increases the number of oxygen-containing functional groups and acidic sites on the surface of activated carbon, improves the pore structure parameters of activated carbon catalyst, and increases the specific surface area and pore volume. Ultrasonic impregnation greatly improves the success rate of active metal loading and the catalyst's resistance to PbCl2 poisoning, reduces catalyst surface agglomeration and improves active metal dispersion. (2) The catalyst of the present invention has strong resistance to PbCl2 poisoning and high removal efficiency in the application of nitrogen oxide removal. It has excellent N2 selectivity and is environmentally friendly and pollution-free. It can effectively solve the problems of low efficiency, high cost, easy blockage and poisoning damage of existing catalysts in flue gas denitrification. (3) The application of the catalyst of the present invention in the removal of nitrogen oxides uses NH3 and CO as common reducing gases, which can overcome the problem of excessive NH3 content and easy escape, and CO itself exists in the flue gas, reducing cost consumption; reducing the content of CO as a reducing agent can reduce the problem of catalyst poisoning, and the defects are overcome by each other to achieve the coexistence of dual technical advantages. Attached Figure Description

[0016] Figure 1 This is a comparison chart of the denitrification rates of the catalysts in Examples 1-3; Figure 2 Here are the SEM images and EDS images of each element of the catalyst in Example 1; Figure 3 Here are the SEM images and EDS images of each element of the catalyst in Example 2; Figure 4 Here are the SEM images and EDS images of each element of the catalyst in Example 3; Figure 5 The chart shows a comparison of the denitrification rates of the catalysts in Examples 4-6. Detailed Implementation

[0017] 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.

[0018] The catalytic reactor used in this embodiment of the invention is a CHY-1200 vertical fixed reactor. The reducing gas, protective atmosphere, and simulated flue gas are preheated before entering the reactor, and the reaction temperature is 100~250℃. The simulated flue gas composition and flow rate are as follows: NO flow rate is 4 ml·min. -1 The O2 volume concentration is 9%, and the ammonia gas flow rate in nitrogen is 400 ml·min. -1 The flow rate of the reducing gas CO is 15 ml / min. -1 The PbCl2 gas flow rate is 1 ml·min -1 N2 is used as the equilibrium gas with a flow rate of 580 ml·min. -1 The total gas flow rate is 1000 ml / min. -1 ; The NO removal activity of the catalyst was evaluated using NO conversion and N2 selectivity, and the calculation method is as follows: (1) (2) In the formula: ------NO concentration at reactor inlet, ppm; -----NO concentration at reactor outlet, ppm; ----NO2 concentration at reactor outlet, ppm; ----N2O concentration at reactor outlet, ppm.

[0019] Example 1: This example describes a nitrogen oxide removal catalyst resistant to PbCl2 poisoning. The support is dual-activated coconut shell activated carbon, and the active components are iron oxides, specifically FeO and Fe2O3. The total content of metal elements (Fe) in the active components is 6.5% of the mass of the coconut shell activated carbon. The preparation method of the PbCl2 poisoning-resistant catalyst for removing nitrogen oxides is as follows: (1) Add coconut shell activated carbon to deionized water, ultrasonically clean at 60°C for 2 hours, separate solid and liquid, and dry to obtain clean coconut shell activated carbon. (2) Air was introduced into the clean coconut shell activated carbon at a rate of 700 ml / min and activated at 800℃ (reacting with CO2 and H2O in the air) for 4 h. After cooling to room temperature, a primary activated coconut shell activated carbon was obtained. The primary activated coconut shell activated carbon was added to a nitric acid solution with a concentration of 4 mol / L and activated at 80℃ for 2 h. After washing with deionized water, a double activated coconut shell activated carbon carrier was obtained. (3) The dual-activated coconut shell activated carbon support was added to an active metal nitrate solution (Fe(NO3)3 solution) with a concentration of 0.4 mol / L, citric acid (the amount of citric acid added was 2 ml / L) and mixed evenly, and then an alkaline agent (NH3·H2O solution with a concentration of 2 mol / L) was added until the pH was 7. The mixture was ultrasonically impregnated at 80℃ for 1 h, and the solvent was evaporated at 110℃. The resulting product was a dual-activated coconut shell activated carbon catalyst precursor. (4) The dual-activated coconut shell activated carbon catalyst precursor and P2O5 powder were mixed evenly and placed under a protective atmosphere (argon) and calcined at 450°C for 4 hours to obtain a nitrogen oxide removal catalyst resistant to PbCl2 poisoning (Fe / AC catalyst resistant to PbCl2 poisoning); the mass ratio of P2O5 powder to dual-activated coconut shell activated carbon catalyst precursor was 5:100. The SEM images and elemental EDS images of the Fe / AC catalyst resistant to PbCl2 poisoning in this embodiment are shown below. Figure 2 ,like Figure 2 As shown, there are many white substances on the catalyst surface. Combined with EDS analysis, it can be identified as successfully loaded Fe elements and their oxides. Because Fe interacts with the catalyst matrix, i.e., activated carbon, it can inhibit PbCl2 from clogging the pores in the flue gas. Therefore, the catalyst can maintain high resistance to PbCl2 poisoning and NO removal activity.

[0020] In this embodiment, the PbCl2-resistant Fe / AC catalyst was used for denitrification reaction at 100~250℃, and the catalyst loading was 8g. Before the denitrification experiment, a protective atmosphere was introduced into the vertical reactor to remove other gases and eliminate interference. NO in simulated flue gas was introduced for 1 hour to allow the catalyst to adsorb NO to saturation and reduce experimental error. Simulated flue gas (NO flow rate 4 ml·min) -1 The O2 volume concentration is 9%, and the ammonia gas flow rate in nitrogen is 400 ml·min. -1 The flow rate of the reducing gas CO is 15 ml / min. -1The PbCl2 gas flow rate is 1 ml·min -1 N2 is used as the equilibrium gas with a flow rate of 580 ml·min. -1 Total gas flow rate 1000 ml·min -1 After mixing, the mixture is fed into a vertical reactor where, under the action of a PbCl2-resistant catalyst, the reducing gas NH3 and CO reduce NO to N2. The gas after the reaction is collected and purified by a tail gas treatment device and then discharged into the atmosphere. The NO concentration at the inlet and outlet is detected by a flue gas analyzer. In this embodiment, the low-temperature synergistic NO removal efficiency of the PbCl2-resistant Fe / AC catalyst for NH3+CO removal is as follows: Figure 1 As shown, the PbCl2-resistant Fe / AC catalyst maintains a high NO removal efficiency, reaching over 60% even at its lowest point.

[0021] Example 2: This example describes a nitrogen oxide removal catalyst resistant to PbCl2 poisoning. The support is dual-activated coconut shell activated carbon, and the active component is cerium oxide, specifically Ce2O3 and CeO2. The total content of metal element (Ce) in the active component is 6.5% of the mass of the coconut shell activated carbon. The preparation method of the PbCl2 poisoning-resistant catalyst for removing nitrogen oxides is as follows: (1) Add coconut shell activated carbon to deionized water, ultrasonically clean at 65°C for 2.5 h, separate solid and liquid, and dry to obtain clean coconut shell activated carbon; (2) Air was introduced into the clean coconut shell activated carbon at a rate of 800 ml / min and activated at 850°C (reacting with CO2 and H2O in the air) for 4.5 h. After cooling to room temperature, primary activated coconut shell activated carbon was obtained. The primary activated coconut shell activated carbon was added to a 4.5 mol / L nitric acid solution and activated at 85°C for 2.5 h. After washing with deionized water, a double-activated coconut shell activated carbon carrier was obtained. (3) The dual-activated coconut shell activated carbon support was added to an active metal nitrate solution (Ce(NO3)3 solution) with a concentration of 0.5 mol / L, citric acid (the amount of citric acid added was 2.5 ml / L) and mixed evenly. Then, an alkaline agent (NH3·H2O solution with a concentration of 2.5 mol / L) was added until the pH was 6. The mixture was ultrasonically impregnated at 85°C for 1.5 h, and the solvent was evaporated at 100°C. The resulting product was a dual-activated coconut shell activated carbon catalyst precursor. (4) The dual-activated coconut shell activated carbon catalyst precursor and P2O5 powder were mixed evenly and placed under a protective atmosphere (argon) and calcined at 500℃ for 4.5h to obtain a nitrogen oxide removal catalyst resistant to PbCl2 poisoning (Ce / AC catalyst resistant to PbCl2 poisoning); the mass ratio of P2O5 powder to dual-activated coconut shell activated carbon catalyst precursor was 6:100. The SEM images and EDS diagrams of the Ce / AC catalyst resistant to PbCl2 poisoning in this embodiment are shown below. Figure 3 It can be observed that there are fewer white particulates and Ce oxides on the catalyst surface. This is because, under the same loading conditions, Ce has a larger molar mass and a smaller amount of substance. Simultaneously, Ce acts as a promoter, primarily improving the pore structure of the catalyst. Therefore, the catalyst exhibits excellent surface morphology. More micropores can better reduce the impact of PbCl2 pore blockage, thus allowing the catalyst to maintain high resistance to PbCl2 poisoning and NO removal activity.

[0022] In this embodiment, the Ce / AC catalyst resistant to PbCl2 poisoning was used for denitrification reaction at 100~250℃, and the catalyst loading was 8g. Before the denitrification experiment, a protective atmosphere was introduced into the vertical reactor to remove other gases and eliminate interference. NO in simulated flue gas was introduced for 1 hour to allow the catalyst to adsorb NO to saturation and reduce experimental error. Simulated flue gas (NO flow rate 4 ml·min) -1 The O2 volume concentration is 9%, and the ammonia gas flow rate in nitrogen is 400 ml·min. -1 The flow rate of the reducing gas CO is 15 ml / min. -1 The PbCl2 gas flow rate is 1 ml·min -1 N2 is used as the equilibrium gas with a flow rate of 580 ml·min. -1 Total gas flow rate 1000 ml·min -1 After mixing, the mixture is fed into a vertical reactor where, under the action of a PbCl2-resistant catalyst, the reducing gas NH3 and CO reduce NO to N2. The gas after the reaction is collected and purified by a tail gas treatment device and then discharged into the atmosphere. The NO concentration at the inlet and outlet is detected by a flue gas analyzer. In this embodiment, the low-temperature synergistic NO removal efficiency of the PbCl2-resistant Ce / AC catalyst for NH3+CO is as follows: Figure 1 As shown, the PbCl2-resistant Ce / AC catalyst maintains a high NO removal efficiency, reaching over 50% even at its lowest point.

[0023] Example 3: This example describes a nitrogen oxide removal catalyst resistant to PbCl2 poisoning. The support is dual-activated coconut shell activated carbon, and the active components are iron oxides and cerium oxides. The iron oxides are FeO and Fe2O3, and the cerium oxides are Ce2O3 and CeO2. The total content of metal elements in the active components is 6.5% of the mass of coconut shell activated carbon; the mass ratio of Fe to Ce elements in the active components is 1:1. The preparation method of the PbCl2 poisoning-resistant catalyst for removing nitrogen oxides is as follows: (1) Add coconut shell activated carbon to deionized water, ultrasonically clean it at 70°C for 3 hours, separate the solid and liquid, and dry it to obtain clean coconut shell activated carbon. (2) Air was introduced into the clean coconut shell activated carbon at a rate of 900 ml / min and activated at a temperature of 900℃ (reacting with CO2 and H2O in the air) for 5 h. After cooling to room temperature, primary activated coconut shell activated carbon was obtained. The primary activated coconut shell activated carbon was added to a nitric acid solution with a concentration of 5 mol / L and activated at a temperature of 90℃ for 3 h. After washing with deionized water, a double-activated coconut shell activated carbon carrier was obtained. (3) The dual-activated coconut shell activated carbon support was added to a 0.6 mol / L active metal nitrate solution (a mixed solution of Fe(NO3)3 and Ce(NO3)3), citric acid (3 ml / L) was added and mixed evenly, and then an alkaline agent (3 mol / L NH3·H2O solution) was added until the pH was 6.5. The mixture was ultrasonically impregnated at 90°C for 2 h, and the solvent was evaporated at 120°C to obtain the dual-activated coconut shell activated carbon catalyst precursor. (4) The dual-activated coconut shell activated carbon catalyst precursor and P2O5 powder were mixed evenly and placed under a protective atmosphere (argon) and calcined at 550°C for 5 hours to obtain a nitrogen oxide removal catalyst resistant to PbCl2 poisoning (Fe-Ce / AC catalyst resistant to PbCl2 poisoning); the mass ratio of P2O5 powder to dual-activated coconut shell activated carbon catalyst precursor was 7:100. The SEM images and EDS diagrams of the PbCl2 poisoning-resistant Fe-Ce / AC catalyst in this embodiment are shown below. Figure 4 The SEM images revealed that the catalyst surface morphology was superior, with a smooth surface, a large number of micropores, and white particles on the surface. Combined with EDS analysis, these particles were identified as the active components Fe and Ce and their oxides. Due to the strong interaction between Fe, Ce, and the catalyst matrix, the catalyst not only developed a superior pore structure but also prevented PbCl2 from adhering to the catalyst surface. Therefore, the catalyst exhibited superior resistance to PbCl2 poisoning and NO removal activity.

[0024] In this embodiment, the Fe-Ce / AC catalyst resistant to PbCl2 poisoning was used for denitrification reaction at 100~250℃, and the catalyst loading was 8g. Before the denitrification experiment, a protective atmosphere was introduced into the vertical reactor to remove other gases and eliminate interference. NO in simulated flue gas was introduced for 1 hour to allow the catalyst to adsorb NO to saturation and reduce experimental error. Simulated flue gas (NO flow rate 4 ml·min) -1 The O2 volume concentration is 9%, and the ammonia gas flow rate in nitrogen is 400 ml·min. -1 The flow rate of the reducing gas CO is 15 ml / min. -1 The PbCl2 gas flow rate is 1 ml·min -1 N2 is used as the equilibrium gas with a flow rate of 580 ml·min. -1 Total gas flow rate 1000 ml·min -1 After mixing, the mixture is fed into a vertical reactor where, under the action of a PbCl2-resistant catalyst, the reducing gas NH3 and CO reduce NO to N2. The gas after the reaction is collected and purified by a tail gas treatment device and then discharged into the atmosphere. The NO concentration at the inlet and outlet is detected by a flue gas analyzer. In this embodiment, the low-temperature synergistic NO removal efficiency of the PbCl2-resistant Fe-Ce / AC catalyst for NH3+CO is as follows: Figure 1 As shown, the PbCl2-resistant Fe-Ce / AC catalyst maintains a high NO removal efficiency, reaching over 80% even at its lowest point.

[0025] Example 4: The nitrogen oxide removal catalyst resisting PbCl2 poisoning in this example uses double-activated coconut shell activated carbon as the support. The active components are iron oxide and cerium oxide. The iron oxide is FeO and Fe2O3, and the cerium oxide is Ce2O3 and CeO2. The total content of metal elements in the active components is 5% of the mass of coconut shell activated carbon. The mass ratio of Fe to Ce elements in the active components is 1:1. The preparation method of the PbCl2 poisoning-resistant catalyst for removing nitrogen oxides is as follows: (1) Add coconut shell activated carbon to deionized water, ultrasonically clean at 75°C for 3.5 h, separate solid and liquid, and dry to obtain clean coconut shell activated carbon. (2) Air was introduced into the clean coconut shell activated carbon at a rate of 1000 ml / min and activated at 950°C (reacting with CO2 and H2O in the air) for 5.5 h. After cooling to room temperature, primary activated coconut shell activated carbon was obtained. The primary activated coconut shell activated carbon was added to a 5.5 mol / L nitric acid solution and activated at 95°C for 3.5 h. After washing with deionized water, a double-activated coconut shell activated carbon carrier was obtained. (3) The dual-activated coconut shell activated carbon support was added to a 0.7 mol / L active metal nitrate solution (a mixed solution of Fe(NO3)3 and Ce(NO3)3), citric acid (3.5 ml / L) was added and mixed evenly, and then an alkaline agent (sodium hydroxide) was added until the pH was 7.5. The mixture was ultrasonically impregnated at 95°C for 2.5 h, and the solvent was evaporated at 130°C. The dual-activated coconut shell activated carbon catalyst precursor was obtained by drying. (4) The dual-activated coconut shell activated carbon catalyst precursor and P2O5 powder were mixed evenly and placed under a protective atmosphere (argon) and calcined at 600℃ for 5.5h to obtain a nitrogen oxide removal catalyst resistant to PbCl2 poisoning (Fe-Ce / AC catalyst resistant to PbCl2 poisoning); the mass ratio of P2O5 powder to dual-activated coconut shell activated carbon catalyst precursor was 8:100. In this embodiment, the Fe-Ce / AC catalyst resistant to PbCl2 poisoning was used for denitrification reaction at 100~250℃, and the catalyst loading was 8g. Before the denitrification experiment, a protective atmosphere was introduced into the vertical reactor to remove other gases and eliminate interference. NO in simulated flue gas was introduced for 1 hour to allow the catalyst to adsorb NO to saturation and reduce experimental error. Simulated flue gas (NO flow rate 4 ml·min) -1 The O2 volume concentration is 9%, and the ammonia gas flow rate in nitrogen is 400 ml·min. -1 The flow rate of the reducing gas CO is 15 ml / min. -1 The PbCl2 gas flow rate is 1 ml·min -1 N2 is used as the equilibrium gas with a flow rate of 580 ml·min. -1 Total gas flow rate 1000 ml·min -1 After mixing, the mixture is fed into a vertical reactor where, under the action of a PbCl2-resistant catalyst, the reducing gas NH3 and CO reduce NO to N2. The gas after the reaction is collected and purified by a tail gas treatment device and then discharged into the atmosphere. The NO concentration at the inlet and outlet is detected by a flue gas analyzer. In this embodiment, the low-temperature synergistic NO removal efficiency of the PbCl2-resistant Fe-Ce / AC catalyst for NH3+CO is as follows: Figure 5 As shown, the PbCl2-resistant Fe-Ce / AC catalyst maintains a high NO removal efficiency, reaching at least 73.5% even at its lowest.

[0026] Example 5: This example is a nitrogen oxide removal catalyst resistant to PbCl2 poisoning. The support is dual-activated coconut shell activated carbon. The active components are iron oxide and cerium oxide. The iron oxide is FeO and Fe2O3, and the cerium oxide is Ce2O3 and CeO2. The total content of metal elements in the active components is 7% of the mass of coconut shell activated carbon. The mass ratio of Fe to Ce elements in the active components is 1:1. The preparation method of the PbCl2 poisoning-resistant catalyst for removing nitrogen oxides is as follows: (1) Add coconut shell activated carbon to deionized water, ultrasonically clean it at 80°C for 4 hours, separate the solid and liquid, and dry it to obtain clean coconut shell activated carbon. (2) Air was introduced into the clean coconut shell activated carbon at a rate of 1100 ml / min and activated at a temperature of 1000℃ (reacting with CO2 and H2O in the air) for 6 h. After cooling to room temperature, a primary activated coconut shell activated carbon was obtained. The primary activated coconut shell activated carbon was added to a 6 mol / L nitric acid solution and activated at a temperature of 100℃ for 4 h. After washing with deionized water, a double activated coconut shell activated carbon carrier was obtained. (3) The dual-activated coconut shell activated carbon support was added to an active metal nitrate solution (a mixed solution of Fe(NO3)3 and Ce(NO3)3) with a concentration of 0.8 mol / L, citric acid (4 ml / L) was added and mixed evenly, and then an alkaline agent (potassium hydroxide) was added until the pH was 8. The mixture was ultrasonically impregnated at 100°C for 3 h, and the solvent was evaporated at 140°C. The dual-activated coconut shell activated carbon catalyst precursor was obtained by drying. (4) The dual-activated coconut shell activated carbon catalyst precursor and P2O5 powder were mixed evenly and placed under a protective atmosphere (argon) and calcined at 650°C for 6 hours to obtain a nitrogen oxide removal catalyst resistant to PbCl2 poisoning (Fe-Ce / AC catalyst resistant to PbCl2 poisoning); the mass ratio of P2O5 powder to dual-activated coconut shell activated carbon catalyst precursor was 9:100. In this embodiment, the Fe-Ce / AC catalyst resistant to PbCl2 poisoning was used for denitrification reaction at 100~250℃, and the catalyst loading was 8g. Before the denitrification experiment, a protective atmosphere was introduced into the vertical reactor to remove other gases and eliminate interference. NO in simulated flue gas was introduced for 1 hour to allow the catalyst to adsorb NO to saturation and reduce experimental error. Simulated flue gas (NO flow rate 4 ml·min) -1 The O2 volume concentration is 9%, and the ammonia gas flow rate in nitrogen is 400 ml·min. -1 The flow rate of the reducing gas CO is 15 ml / min. -1 The PbCl2 gas flow rate is 1 ml·min -1 N2 is used as the equilibrium gas with a flow rate of 580 ml·min.-1 Total gas flow rate 1000 ml·min -1 After mixing, the mixture is fed into a vertical reactor where, under the action of a PbCl2-resistant catalyst, the reducing gas NH3 and CO reduce NO to N2. The gas after the reaction is collected and purified by a tail gas treatment device and then discharged into the atmosphere. The NO concentration at the inlet and outlet is detected by a flue gas analyzer. In this embodiment, the low-temperature synergistic NO removal efficiency of the PbCl2-resistant Fe-Ce / AC catalyst for NH3+CO is as follows: Figure 5 As shown, the PbCl2-resistant Fe-Ce / AC catalyst maintains a high NO removal efficiency, reaching at least 78.1% even at its lowest.

[0027] Example 6: This example is a nitrogen oxide removal catalyst resistant to PbCl2 poisoning. The support is dual-activated coconut shell activated carbon. The active components are iron oxide and cerium oxide. The iron oxide is FeO and Fe2O3, and the cerium oxide is Ce2O3 and CeO2. The total content of metal elements in the active components is 9% of the mass of coconut shell activated carbon. The mass ratio of Fe to Ce elements in the active components is 1:1. The preparation method of the PbCl2 poisoning-resistant catalyst for removing nitrogen oxides is as follows: (1) Add coconut shell activated carbon to deionized water, ultrasonically clean at 85℃ for 4.5h, separate solid and liquid, and dry to obtain clean coconut shell activated carbon. (2) Air was introduced into the clean coconut shell activated carbon at a rate of 1000 ml / min and activated at a temperature of 1050℃ (reacting with CO2 and H2O in the air) for 6.5 h. After cooling to room temperature, a primary activated coconut shell activated carbon was obtained. The primary activated coconut shell activated carbon was added to a 6.5 mol / L nitric acid solution and activated at a temperature of 105℃ for 4.5 h. After washing with deionized water, a double activated coconut shell activated carbon carrier was obtained. (3) The dual-activated coconut shell activated carbon support was added to an active metal nitrate solution (a mixed solution of Fe(NO3)3 and Ce(NO3)3) with a concentration of 0.9 mol / L, citric acid (4.5 ml / L) was added and mixed evenly, and then an alkaline agent (sodium bicarbonate) was added until the pH was 8.5. The mixture was ultrasonically impregnated at 105°C for 3.5 h, and the solvent was evaporated at 150°C. The dual-activated coconut shell activated carbon catalyst precursor was obtained by drying. (4) The dual-activated coconut shell activated carbon catalyst precursor and P2O5 powder were mixed evenly and placed under a protective atmosphere (argon) and calcined at 700℃ for 6.5h to obtain a nitrogen oxide removal catalyst resistant to PbCl2 poisoning (Fe-Ce / AC catalyst resistant to PbCl2 poisoning); the mass ratio of P2O5 powder to dual-activated coconut shell activated carbon catalyst precursor was 10:100. In this embodiment, the Fe-Ce / AC catalyst resistant to PbCl2 poisoning was used for denitrification reaction at 100~250℃, and the catalyst loading was 8g. Before the denitrification experiment, a protective atmosphere was introduced into the vertical reactor to remove other gases and eliminate interference. NO in simulated flue gas was introduced for 1 hour to allow the catalyst to adsorb NO to saturation and reduce experimental error. Simulated flue gas (NO flow rate 4 ml·min) -1 The O2 volume concentration is 9%, and the ammonia gas flow rate in nitrogen is 400 ml·min. -1 The flow rate of reducing gas CO is 16 ml·min. -1 N2 is used as the equilibrium gas with a flow rate of 580 ml·min. -1 Total gas flow rate 1000 ml·min -1 After mixing, the mixture is fed into a vertical reactor where, under the action of a PbCl2-resistant catalyst, the reducing gas NH3 and CO reduce NO to N2. The gas after the reaction is collected and purified by a tail gas treatment device and then discharged into the atmosphere. The NO concentration at the inlet and outlet is detected by a flue gas analyzer. In this embodiment, the low-temperature synergistic NO removal efficiency of the PbCl2-resistant Fe-Ce / AC catalyst for NH3+CO is as follows: Figure 5 As shown, the PbCl2-resistant Fe-Ce / AC catalyst maintains a high NO removal efficiency, reaching at least 70.9% even at its lowest.

[0028] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A nitrogen oxide removal catalyst which is resistant to PbCl2poisoning, characterized by: The carrier is double-activated coconut shell activated carbon, the active component is iron oxide and / or cerium oxide, the iron oxide is FeO and Fe2O3, the cerium oxide is Ce2O3 and CeO2, and the total content of metal elements in the active component is 5-9% of the mass of the coconut shell activated carbon; when the active component is iron oxide and cerium oxide, the mass ratio of Fe to Ce in the active component is 1:

1.

2. The method of claim 1 for the preparation of a nitrogen oxide removal catalyst which is resistant to poisoning by PbCl2, characterized in that The specific steps are as follows: (1) The coconut shell activated carbon is added to deionized water, ultrasonic cleaning is performed at a temperature of 60-85°C, solid-liquid separation is performed, and drying is performed to obtain clean coconut shell activated carbon; (2) Air is introduced into the clean coconut shell activated carbon, activation treatment is performed at a temperature of 800-1050°C for 4-6.5h, and cooling to room temperature is performed to obtain first-activated coconut shell activated carbon; the first-activated coconut shell activated carbon is added to a nitric acid solution for activation treatment, and deionized water is used for cleaning to obtain a double-activated coconut shell activated carbon carrier; (3) The double-activated coconut shell activated carbon carrier is added to an active metal nitrate solution, citric acid is added and mixed uniformly, an alkaline agent is added to a pH of 6-8.5, ultrasonic immersion is performed, the solvent is evaporated and dried to obtain a double-activated coconut shell activated carbon catalyst precursor; (4) The double-activated coconut shell activated carbon catalyst precursor is mixed uniformly with P2O5 powder, placed in a protective atmosphere, and calcined at a temperature of 450-700°C for 4-6.5h to obtain a nitrogen oxide removal catalyst resistant to PbCl2 poisoning.

3. The process for desilication and decalcification of siliceous cupric oxide ores by stage flotation according to claim 2, characterized in that: The air introduction rate in step (2) is 700-1200ml / min.

4. The process for desilication and decalcification of siliceous cupric oxide ore by stage flotation according to claim 1, characterized in that: The concentration of the nitric acid solution in step (2) is 4-6.5mol / L, the activation temperature is 80-105°C, and the time is 2-4.5h.

5. The process for desilication and decalcification of siliceous cupric oxide ore by stage flotation according to claim 2, characterized by: The active metal nitrate in step (3) is Fe(NO3)3·9H2O and / or Ce(NO3)2·6H2O, the total concentration of metal salts in the active metal nitrate solution is 0.4-0.9mol / L, the addition amount of citric acid is 2-4.5mol / L, and the alkaline agent is sodium hydroxide, potassium hydroxide, ammonia water, sodium bicarbonate or sodium carbonate.

6. The process for desilication and decalcification of siliceous cupric oxide ore by stage flotation according to claim 5, characterized in that: The ultrasonic immersion temperature is 80-105°C, and the immersion time is 1-3.5h; the evaporation and drying temperature is 100-150°C.

7. The process for desilication and decalcification of siliceous cupric oxide ore by stage flotation according to claim 2, characterized by: The mass ratio of P2O5 powder to double-activated coconut shell activated carbon catalyst precursor in step (5) is 5-10:

100.

8. The process for desilication and decalcification of siliceous cupric oxide ore by stage flotation according to claim 2, characterized by: The protective gas in step (5) is nitrogen or inert gas.

9. Use of the nitrogen oxide removal catalyst according to claim 1, which is resistant to poisoning by PbCl2, as catalyst for the removal of nitrogen oxides, characterized in that: NH3 and CO are used as reducing agents, and the catalytic temperature is 100-250°C.

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