Air pollution denitrification and desulfurization tail gas purification methods

Abstract

This invention relates to the field of air pollution control technology, specifically to a method for purifying exhaust gas from air pollution denitrification and desulfurization, including: cyclone spray desulfurization (using nano-scale composite absorbent slurry to efficiently absorb SO2 and remove particulate matter in a cyclone reactor), and two-stage catalytic denitrification (using nano-catalysts in a low-temperature zone to promote NO removal). x The process involves reduction, enhanced reaction in a high-temperature zone using a novel honeycomb ceramic carrier to support a vanadium-tungsten-titanium-based catalyst, deep synergistic purification (further removal of residual pollutants and aerosols through electrostatic dust removal coupled with oxidation adsorption), and an intelligent control system (real-time optimization of absorbent ratio, catalyst temperature, and flow rate parameters). This method addresses the problems of catalyst poisoning, high energy consumption, and insufficient treatment efficiency in traditional processes by modifying the absorbent with nanomaterials, employing temperature gradient catalytic reactions, and utilizing a multi-pollutant synergistic removal mechanism. The system achieves a desulfurization efficiency ≥98%, a denitrification efficiency ≥97%, and particulate matter emissions ≤10 mg / m³. 3 SO2 ≤ 35 mg / m³ 3 NO x ≤50mg / m 3 It meets ultra-low emission standards.

Description

Technical Field

[0001] This invention relates to the field of air pollution control technology, specifically to a method for purifying exhaust gas from air pollution denitrification and desulfurization. Background Technology

[0002] Industrial combustion processes (such as coal-fired power generation, steel smelting, and chemical production) emit exhaust gases containing large amounts of SO2 and NO. x Particulate matter and other pollutants are major sources of acid rain, smog, and photochemical pollution. Traditional treatment processes face the following bottlenecks:

[0003] Defects of desulfurization technology:

[0004] Wet desulfurization (such as limestone-gypsum process): The technology is mature but the equipment is large and energy-intensive, the absorbent utilization rate is low (only 60-80%), and a large amount of wastewater and waste residue need to be treated. The slurry nozzles are prone to clogging, the equipment is severely corroded, and the absorption efficiency for low concentrations of SO2 decreases.

[0005] Semi-dry / dry desulfurization (such as SDA, LIFAC): low desulfurization efficiency (70-90%), dependent on high temperature environment or ultrafine powder, poor adaptability and difficult to handle by-products.

[0006] Denitrification technology challenges:

[0007] Selective catalytic reduction (SCR): The mainstream technology has high denitrification efficiency (≥85%), but the catalyst has a narrow activity window (requires 280-420℃) and is easily poisoned and deactivated by pollutants such as fly ash and SO2 in flue gas; the efficiency drops significantly in the low temperature range (<200℃), and additional heating equipment is required, increasing costs.

[0008] Selective non-catalytic reduction (SNCR): has a narrower reaction temperature window (850-1100℃), high ammonia slip rate (>5ppm), and denitrification efficiency of only 40-60%, making it difficult to meet ultra-low emission requirements.

[0009] Systemic problems of traditional processes:

[0010] Separating desulfurization and denitrification equipment results in a long process chain, large footprint, complex operation, poor coordination, and the entry of wet flue gas after desulfurization into the denitrification system can easily cause catalyst blockage or corrosion.

[0011] Energy consumption and cost pressures: High-energy-consuming slurry circulation, flue gas reheating, and complex wastewater treatment systems significantly increase operating costs.

[0012] Emerging technological bottlenecks: The commercialization of technologies such as biological methods and electron beam / pulse corona discharge methods is insufficient, and the equipment costs are high and the stability is poor, making it difficult to apply on a large scale.

[0013] New requirements for ultra-low emissions:

[0014] National and local environmental protection standards (such as the "Emission Standard for Air Pollutants from Boilers") require particulate matter to be ≤10mg / m³. 3 SO2 ≤ 35 mg / m³ 3 NO x ≤50mg / m 3 However, existing processes lack stability in meeting standards under complex operating conditions (such as high-sulfur and high-dust flue gas and low-load operation), and it is particularly difficult to balance deep purification with economic efficiency.

[0015] In summary, there is an urgent need for an integrated, efficient, low-energy-consumption, and highly adaptable multi-pollutant synergistic purification process to break through existing technological bottlenecks and achieve stable ultra-low emissions of industrial exhaust gas. Summary of the Invention

[0016] The purpose of this invention is to provide a method for purifying exhaust gas from denitrification and desulfurization of air pollution. By using multi-stage synergistic purification, nanomaterial-modified absorbents, temperature gradient catalysis, and intelligent control systems, this method solves the problems of catalyst poisoning, high energy consumption, insufficient efficiency, and poor synergy in traditional processes, thereby achieving deep purification and ultra-low emissions of industrial exhaust gas.

[0017] The technical solution adopted by this invention to solve its technical problem is: a method for purifying tail gas from denitrification and desulfurization of air pollution, comprising the following steps:

[0018] a. Dust Pretreatment: The exhaust gas is treated by a cyclone dust collector to remove particles >10μm in diameter, and then further treated by a wet electrostatic precipitator (WESP) to remove fine particles down to ≤10mg / m³. 3 ;

[0019] b. Cyclone spray desulfurization: For dust content ≤10mg / m³ 3 The flue gas is introduced into a cyclone desulfurization tower and subjected to countercurrent spray washing using a nano-composite absorbent slurry (a mixture of calcium hydroxide with a particle size ≤100nm, nano-titanium dioxide, and a dispersant). The slurry pH is controlled at 5.8-6.5, and the liquid-to-gas ratio is 0.8-1.2L / m³. 3 The residence time inside the tower is ≥3s to absorb SO2 and remove residual particulate matter;

[0020] c. Two-stage catalytic denitrification: After desulfurization, the flue gas is heated to 180-250℃ via a heat exchanger and enters the first-stage denitrification reactor, where ammonia reducing agent (NH3 / NO3) is injected. x (Molar ratio 0.9-1.1) NO reduction under the catalysis of a nanocatalyst layer (a honeycomb ceramic support loaded with iron-based active components). x Further heating to 280-350℃ before entering the second-stage reactor, where deep denitrification is enhanced by a vanadium-tungsten-titanium-based catalyst (V2O5-WO3 / TiO2, loading 5-10wt%).

[0021] d. Deep Synergistic Purification: After denitrification, the flue gas enters the composite purification tower, where it is coupled with porous adsorption materials (modified activated carbon / silica) through an electrostatic field to remove residual SO2 and NO. x and aerosols;

[0022] e. Intelligent control system: Real-time monitoring of parameters such as inlet pollutant concentration, temperature, and pressure, and dynamic adjustment of absorbent supply, catalyst heating power, and slurry circulation flow rate.

[0023] The method utilizes nanomaterial-modified absorbents, temperature gradient catalytic reactions, and cyclone reactor design to achieve SO2 removal rates ≥98% and NO removal rates ≥98%. x Removal rate ≥97%, particulate matter emission ≤10mg / m³ 3 SO2 ≤ 35 mg / m³ 3 NO x ≤50mg / m 3 .

[0024] Specifically, the nanocomposite absorbent slurry contains 65-85% calcium hydroxide, 10-20% nano titanium dioxide (particle size 20-50nm) and 5-15% dispersant (sodium carboxymethyl cellulose) by mass, and the slurry solid content is 10-15%.

[0025] Specifically, in the two-stage catalytic denitrification process, the temperature of the first-stage reactor is controlled at 180-220℃, the temperature of the second-stage reactor is controlled at 300-350℃, and the total contact time between the two catalyst layers is ≥2.5s.

[0026] Specifically, the cyclone desulfurization tower is equipped with a cyclone blade guide device to generate cyclone motion in the flue gas, prolonging the gas-liquid contact time to ≥3.5s and improving the mass transfer efficiency.

[0027] Specifically, in the deep collaborative purification step, the electrostatic dust removal electric field strength is 20-30kV / cm, the adsorption material layer thickness is 0.5-1.5m, and the removal efficiency is ≥95%.

[0028] Specifically, the intelligent control system dynamically adjusts the NH3 injection rate (fluctuation range ≤ ±5%) and slurry circulation flow rate (fluctuation range ≤ ±10%) based on the inlet pollutant concentration.

[0029] Specifically, the absorbent slurry is recycled through a seed crystal recycling system with a regeneration rate of ≥90%, reducing solid waste emissions.

[0030] Specifically, the exhaust gas pretreatment adopts a series connection of wet electrostatic precipitator and cyclone dust collector, with a particulate matter removal efficiency of ≥99%.

[0031] Specifically, the nanocatalyst comprises iron-based active sites (Fe3O4 loading 3-7 wt%) and a honeycomb ceramic support, with a specific surface area ≥200 m². 2 / g, abrasion resistance ≥80N / cm 2 .

[0032] Specifically, the method is applicable to the purification of sulfur- and nitrate-containing industrial tail gas emitted from coal-fired boilers, sintering machines, industrial kilns, etc., with a gas volume range of 10. 3 -10 6 m 3 / h.

[0033] The beneficial effects of this invention are:

[0034] High-efficiency pollutant removal: Cyclone nano-desulfurization coupled with two-stage catalytic denitrification achieves SO2 removal rate ≥98% and NO... x ≥97%, particulate matter emissions ≤10mg / m³ 3 It far exceeds the national standard requirements.

[0035] Nanomaterial enhancement: Nano-absorbent slurry significantly improves SO2 absorption rate and mass transfer efficiency, reducing slurry usage; Low-temperature nano-catalysts broaden the reaction temperature window, avoiding the high-temperature dependence and catalyst poisoning problems of traditional SCR.

[0036] Energy consumption and cost optimization: The cyclone tower structure improves gas-liquid mixing efficiency and reduces slurry circulation energy consumption; the two-stage denitrification integrates waste heat utilization to reduce heating requirements; intelligent control avoids excessive ammonia injection and slurry waste.

[0037] Adaptability and stability: The process design is adapted to complex operating conditions such as high-sulfur and high-dust flue gas and low-load fluctuations; the catalyst wear resistance is ≥80 N / cm. 2 The lifespan is extended; modular equipment facilitates maintenance and modification.

[0038] Environmentally friendly: zero wastewater discharge (slurry regeneration and recycling), gypsum by-product can be utilized as a resource, and there is no secondary pollution. Attached Figure Description

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0040] Figure 1 A flowchart of the method for purifying exhaust gas from denitrification and desulfurization of air pollution provided by the present invention;

[0041] Figure 2 A schematic diagram of the temperature gradient control of the catalyst bed in the two-stage denitrification reactor for the atmospheric pollution denitrification and desulfurization tail gas purification method provided by the present invention. Detailed Implementation

[0042] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0043] like Figures 1-2 As shown, the method for purifying exhaust gas from air pollution denitrification and desulfurization according to the present invention includes the following steps:

[0044] Dust pretreatment: The exhaust gas first passes through a cyclone dust collector to remove large dust particles (particle size > 10μm), and then passes through a wet electrostatic precipitator (WESP) to further remove fine particulate matter to ≤10mg / m³. 3 WESP uses a high-voltage electric field to charge and condense aerosols and droplets, achieving a removal efficiency of ≥99%, while reducing the risk of wear and tear on subsequent desulfurization and denitrification equipment.

[0045] Cyclone spray desulfurization: For dust concentrations ≤10mg / m³ 3 Flue gas is introduced into a cyclone desulfurization tower and subjected to countercurrent spray washing using a nano-composite absorbent slurry. The slurry is composed of calcium hydroxide (65-85%) with a particle size ≤100nm, nano-titanium dioxide (TiO2, 20-50nm, 10-20%), and a dispersant (such as sodium carboxymethyl cellulose, 5-15%), with a solid content of 10-15% and a pH controlled at 5.8-6.5. Guide vanes are installed inside the cyclone tower to generate high-speed rotation of the flue gas, extending the gas-liquid contact time to ≥3.5s and improving mass transfer efficiency. The nanomaterials significantly increase the specific surface area, accelerating the SO2 absorption reaction (Ca(OH)2 + SO2 → CaSO3 + H2O). Simultaneously, TiO2 synergistically catalyzes the oxidation to gypsum (CaSO4·2H2O). The slurry is reused through a recycling system (regeneration rate ≥90%), reducing solid waste emissions.

[0046] Two-stage catalytic denitrification: After desulfurization, the flue gas is heated to the first-stage denitrification temperature window (180-220℃) via a heat exchanger and enters a reactor filled with nano-catalysts (iron-based active sites supported on a honeycomb ceramic support, with Fe3O4 loading of 3-7wt%). Ammonia reducing agent (NH3 / NO3) is then injected. x (Molar ratio 0.9-1.1). Low-temperature nanocatalysts reduce the activation energy of the reaction through highly dispersed active sites, efficiently removing NO in the low-temperature region. x The temperature is further increased to a second high-temperature window (300-350℃), and a vanadium-tungsten-titanium-based catalyst (V2O5-WO3 / TiO2, loading 5-10wt%) is used to enhance the reaction. The two-stage catalyst series design expands the temperature adaptability range, covers the requirements of complex operating conditions, and the total contact time ≥2.5s ensures deep denitrification.

[0047] Deep synergistic purification: After denitrification, the flue gas enters the composite purification tower, where it couples with the modified adsorption material (activated carbon / SiO2) through an electrostatic field to further remove residual SO2 and NO. x And aerosols. The electrostatic precipitator with an electric field strength of 20-30kV / cm destroys the stability of aerosols, and the adsorption layer thickness of 0.5-1.5m achieves molecular-level interception, with an overall removal efficiency of ≥95%.

[0048] Intelligent control system: Real-time monitoring of inlet pollutant concentration, temperature, pressure and slurry parameters, dynamically optimizing absorbent supply (accuracy ±5%), catalyst heating power and slurry circulation flow rate (fluctuation range ±10%), ensuring that the system operates under optimal conditions, balancing efficiency and energy consumption.

[0049] Example 1: High-efficiency purification under normal operating conditions

[0050] Gas processing capacity: 10 5 m 3 / h (Typical operating conditions of flue gas from coal-fired boilers)

[0051] Pollutant inlet concentration: SO2 = 1500 mg / m³ 3 NO x =400mg / m 3 Particulate matter = 80 mg / m³ 3

[0052] Process parameters:

[0053] Dust pretreatment: Cyclone dust collector + WESP in series, particulate matter outlet concentration = 9.2 mg / m³ 3 .

[0054] Cyclone spray desulfurization:

[0055] Nano absorbent formulation: Ca(OH)2 = 75%, TiO2 nanoparticles (30nm) = 15%, dispersant = 10%, slurry solid content 12%, pH = 6.2.

[0056] The liquid-to-gas ratio of the cyclone separator is 1.0 L / m³. 3 Residence time ≈ 3.6s, outlet SO2 = 22mg / m³ 3 (Absorption rate ≈ 98.5%), particulate matter ≤ 10 mg / m³ 3 .

[0057] Two-stage catalytic denitrification:

[0058] First-stage reactor temperature = 200℃, NH3 / NO x =1.0, contact time of nanocatalyst layer (Fe3O4 loaded 5wt%) 1.2s, NO x Reduced to 180 mg / m 3.

[0059] The second stage involves heating to 320℃, with a V2O5-WO3 / TiO2 catalyst contact time of 1.5 s, and the outlet NO... x =28mg / m 3 (Total denitrification rate ≈ 93%).

[0060] Deep synergistic purification: electrostatic field strength 25kV / cm, adsorption layer thickness 1.0m, final emission: SO2=22mg / m³ 3 NO x =25mg / m 3 Particulate matter = 7 mg / m³ 3 .

[0061] System performance: Meets ultra-low emission standards (SO2≤35, NO2≤35%) x ≤50), ammonia slip <3ppm, energy consumption is reduced by 15% compared with traditional process.

[0062] Example 2: Enhanced Treatment of High-Sulfur Flue Gas

[0063] Gas processing capacity: 120,000 m³ 3 / h (Steel sintering machine flue gas, high sulfur condition)

[0064] Pollutant inlet concentration: SO2 = 3000 mg / m³ 3 (Exceeding the upper limit), NO x =350mg / m 3 Particulate matter = 120 mg / m³ 3

[0065] Process parameter adjustment:

[0066] Nano-absorbent optimization: Ca(OH)2 = 80%, TiO2 nanoparticles = 12%, dispersant = 8%, slurry solid content 13%, pH = 6.0 (enhancing acid absorption capacity).

[0067] Cyclone column parameters: liquid-to-gas ratio = 1.1 L / m³ 3 The guide vanes enhance the swirl intensity, and the residence time is approximately 3.8 seconds.

[0068] Intelligent control response: The SO2 concentration at the inlet triggers a slurry circulation rate increase of 10%, ensuring an absorption rate of ≥98%.

[0069] Processing result:

[0070] SO2 after desulfurization = 38 mg / m³ 3 (Absorption rate ≈ 98.7%), NO x =350mg / m 3 (Denitrification not started).

[0071] Two-stage denitrification: The second stage temperature is increased to 330℃, and the outlet NO x =32mg / m 3 .

[0072] Final emissions: SO2 = 35 mg / m³ 3 (Critical compliance), NO x =30mg / m 3 Particulate matter = 8 mg / m³ 3 .

[0073] Adaptability verification: Through dynamic control of slurry ratio and flow rate, the system successfully handled ultra-high sulfur loads and operated stably.

[0074] Example 3: Optimization of Low Temperature and Low Dust Operating Conditions

[0075] Gas processing capacity: 80,000 m³ 3 / h (Chemical exhaust gas, low dust and low temperature fluctuations)

[0076] Pollutant inlet concentration: SO2 = 800 mg / m³ 3 NO x =200mg / m 3 Particulate matter = 15 mg / m³ 3 (Low dust), temperature fluctuation 180-220℃.

[0077] Process parameter adjustment:

[0078] The two-stage denitrification focuses on: the first-stage reactor is the main reactor (temperature controlled at 200℃), and the contact time of the nano-catalyst (Fe3O4 loaded with 6wt%) is extended to 1.5s; the lower limit of the second-stage temperature is 300℃.

[0079] Fine control of slurry: pH=5.9, dispersant increases fluidity to adapt to low temperature and avoid freezing risk.

[0080] Processing result:

[0081] SO2 after desulfurization = 12 mg / m³ 3 NO x =200mg / m 3 .

[0082] NO after denitrification x =12mg / m 3 (Overall efficiency ≈ 94%), final emissions: SO2 = 10 mg / m³ 3 NO x =10mg / m 3 Particulate matter = 5 mg / m³ 3 .

[0083] Effects: It operates efficiently in low-temperature and low-dust environments, and the nanocatalyst compensates for the loss of activity at low temperatures.

[0084] Example 4: Validation of Catalyst Ratio Gradient

[0085] Comparative experimental design: Adjust the iron loading of the nanocatalyst and the V2O5-WO3 ratio to test the differences in denitrification efficiency.

[0086] Variant A: First-stage nanocatalyst Fe3O4 = 3wt%, second-stage V2O5 = 5wt%.

[0087] Variant B (preferred in this invention): Fe3O4 = 5 wt%, V2O5 = 7 wt%.

[0088] Variant C: Fe3O4 = 7 wt%, V2O5 = 10 wt%.

[0089] Gas processing capacity: 10 5 m 3 / h, Pollutant inlet: SO2 = 1200 mg / m³ 3 NO x =300mg / m 3 .

[0090] result:

[0091] Variant A: NO x Residue = 55mg / m 3 (Close to the upper limit), ammonia slip is high (>5ppm).

[0092] Variant B (Example): NO x =22mg / m 3 Efficiency 93%, escape <3ppm.

[0093] Variant C: 94% efficiency, but significantly increased catalyst cost.

[0094] Conclusion: The claims with Fe3O4 loading of 3-7 wt% and V2O5-WO3 / TiO2 loading of 5-10 wt% are fully covered, and variant B is the optimal balance point between economy and efficiency.

[0095] Example 5: Equipment Variation and Energy Consumption Testing

[0096] Process equipment adjustment:

[0097] The tilt angle of the guide vanes in the cyclone desulfurization tower was optimized (original design 30° → 45° in the embodiment to enhance the cyclone intensity).

[0098] Replace the electrostatic adsorption layer material (activated carbon → zeolite molecular sieve) and test the resistance and removal efficiency.

[0099] Pollutant inlet: SO2 = 1800 mg / m³ 3 NO x =350mg / m 3 Particulate matter = 60 mg / m³ 3 .

[0100] Processing result:

[0101] The residence time in the cyclone tower was increased to 4.0 s, and the SO2 absorption rate was increased to 98.8%, but the energy consumption for slurry circulation increased by 5%.

[0102] The resistance of the zeolite adsorption layer is reduced by 10%, the deep purification efficiency is maintained at ≥95%, and the overall energy consumption remains the same.

[0103] Verification conclusion: Variations such as the tilt angle of the swirl blades and the adsorption material can be flexibly adjusted within the framework of the claims without affecting the core invention effect, further demonstrating the process adaptability and stability.

[0104] Comparative Example (Comparison with Traditional Processes)

[0105] Using limestone wet desulfurization + high-temperature SCR denitrification to treat the same gas volume (10 5 m 3 / h), inlet pollutant concentration (SO2 = 1500 mg / m³) 3 NO x =400mg / m 3 ) smoke:

[0106] SO2 emissions = 52 mg / m³ 3 (Absorption rate ≈ 96.5%), NO x =65mg / m 3 (Efficiency ≈ 84%), Particulate matter = 12 mg / m³ 3 (Approaching the upper limit).

[0107] High energy consumption (slurry circulation + flue gas reheating), ammonia slip >8ppm, and short catalyst life (requires frequent replacement).

[0108] Comparative advantages: The present invention significantly improves process efficiency, reduces energy consumption and costs, and ensures more stable and compliant emissions.

[0109] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for purifying exhaust gas from air pollution denitrification and desulfurization, characterized in that, Includes the following steps: a. Dust Pretreatment: The exhaust gas is treated by a cyclone dust collector to remove particles >10μm in diameter, and then further treated by a wet electrostatic precipitator to remove fine particles down to ≤10mg / m³. 3 The wet electrostatic precipitator is connected in series with a cyclone dust collector, achieving a particulate matter removal efficiency of ≥99%. b. Cyclone spray desulfurization: For dust content ≤10mg / m³ 3 The flue gas is introduced into a cyclone desulfurization tower, where it is scrubbed counter-currently with a nano-composite absorbent slurry. The slurry pH is controlled at 5.8-6.5, and the liquid-to-gas ratio is 0.8-1.2 L / m³. 3 The residence time inside the tower is ≥3s, absorbing SO2 and removing residual particulate matter; the nanocomposite absorbent slurry contains 65-85% calcium hydroxide, 10-20% nano-titanium dioxide with a particle size of 20-50nm and 5-15% dispersant by mass percentage, and the solid content of the slurry is 10-15%, wherein the dispersant is sodium carboxymethyl cellulose. The absorbent slurry is recycled through a seed crystal recycling system with a regeneration rate ≥90%. c. Two-stage catalytic denitrification: After desulfurization, the flue gas is heated to 180-250℃ via a heat exchanger and enters the first-stage denitrification reactor, where NH3 / NO3 is injected. x Ammonia reducing agent with a molar ratio of 0.9-1.1 reduces NO under the catalysis of a nanocatalyst layer on a honeycomb ceramic support loaded with iron-based active components. x Further heating to 280-350℃ before entering the second-stage reactor, where deep denitrification is enhanced by a vanadium-tungsten-titanium-based catalyst with a loading of 5-10wt% of V2O5-WO3 / TiO2. d. Deep Synergistic Purification: After denitrification, the flue gas enters the composite purification tower, where it is coupled with porous adsorption materials through an electrostatic field to remove residual SO2 and NO. x and aerosols; the electric field strength of the electrostatic field is 20-30 kV / cm, the thickness of the adsorption material layer is 0.5-1.5 m, and the removal efficiency is ≥95%; e. Intelligent control system: Real-time monitoring of inlet pollutant concentration, temperature, and pressure parameters; dynamic adjustment of absorbent supply, catalyst heating power, and slurry circulation flow rate; dynamic adjustment of NH3 injection volume and slurry circulation flow rate based on inlet pollutant concentration; The cyclone desulfurization tower is equipped with a cyclone blade guide device to generate cyclone motion in the flue gas and extend the gas-liquid contact time to ≥3.5s; The nanocatalyst comprises iron-based active sites and a honeycomb ceramic support, with a specific surface area ≥200m². 2 / g, abrasion resistance ≥80N / cm 2 .

2. The method for purifying exhaust gas from air pollution denitrification and desulfurization according to claim 1, characterized in that: In the two-stage catalytic denitrification process, the temperature of the first-stage reactor is controlled at 180-220℃, the temperature of the second-stage reactor is controlled at 300-350℃, and the total contact time between the two catalyst layers is ≥2.5s.

Images