A method for integrated treatment of PH3 catalytic oxidation and liquid absorption

Abstract

The application discloses a PH3 catalytic oxidation-liquid phase absorption integrated treatment method. After dust removal, mist removal and control of the total volume fraction of combustible gas to not higher than 5.0%, PH3-containing gas is mixed with oxygen-containing gas, the mixed gas is contacted with a supported Cu-Mn composite oxide catalyst under certain conditions, and PH3 is oxidized into phosphorus oxide; the obtained gas enters an alkaline circulation absorption process within 0.1-2.0 s, and the phosphorus oxide is absorbed under the conditions of 15-45 DEG C, pH 8.0-11.5, liquid-gas ratio 0.5-8.0 L / m 3 During operation, the oxygen supply and absorption conditions are adjusted according to the import and export PH3, O2, temperature rise and absorption liquid parameters, and short-time cleaning and inert gas purging are implemented when the pressure difference or the outlet PH3 rises. The method cooperatively controls PH3 deep removal and phosphorus resource recovery through gas phase selective oxidation and liquid phase rapid capture, and is suitable for continuous treatment of PH3-containing tail gas with different concentrations.

Description

Technical Field

[0001] This invention belongs to the field of toxic phosphorus-containing gas purification and phosphorus resource recovery technology, specifically involving an integrated treatment method of PH3 catalytic oxidation-liquid phase absorption. Background Technology

[0002] Phosphine (PH3) is a colorless, highly toxic, and flammable reducing gas that can be generated in processes such as yellow phosphorus production and tail gas utilization, alkaline hydrolysis of mud phosphorus to produce hypophosphite, hydrolysis of metal phosphides, semiconductor doping, and grain fumigation. In addition to PH3, gases related to yellow phosphorus production may also contain carbon monoxide, hydrogen, elemental phosphorus vapor, phosphorus oxides, hydrogen sulfide, hydrogen fluoride, water vapor, and dust. The concentration of PH3, oxygen content, and combustible components in tail gases from different sources vary considerably, making direct treatment under single, fixed conditions impossible.

[0003] The toxicity and flammability / explosiveness of PH3 necessitate that treatment systems must simultaneously consider purification efficiency and process safety. Publicly available data from the National Institute for Occupational Safety and Health (NIOSH) in the United States lists the recommended time-weighted average exposure concentration (TWAP) of PH3 as 0.3 ppm, the short-term exposure concentration as 1 ppm, and the immediate life-and-health threat concentration as 50 ppm; publicly available safety data states its lower explosive limit in air is approximately 1.79%. These values ​​pertain to occupational health and hazard assessment and are not equivalent to industrial exhaust emission limits, but they underscore the necessity of PH3 analysis, closed-loop transportation, oxygen control, and emergency inerting. Especially with yellow phosphorus furnace gas containing large amounts of carbon monoxide or hydrogen, direct introduction of air or oxygen could form a combustible mixture or lead to CO or H2 oxidation on copper-manganese or other oxidation catalysts, causing rapid bed heating. Therefore, this invention does not directly use untreated CO-rich yellow phosphorus furnace gas as the target for oxygen supply and catalytic oxidation, but requires the recovery or utilization of combustible gas first, or dilution with an inert gas to a predetermined range.

[0004] Existing methods for PH3 purification mainly include adsorption, liquid-phase oxidation absorption, solid-phase catalytic oxidation, and thermal decomposition. Adsorption is suitable for low-concentration, small-volume exhaust gases and involves simple equipment, but its adsorption capacity is limited. Moisture, hydrogen sulfide, and particulate matter can compete for adsorption or deactivate the adsorbent, and saturated adsorbents require regeneration or disposal as hazardous materials. Liquid-phase oxidation absorption using hypochlorite, permanganate, hydrogen peroxide, or strong acids can convert PH3 into hypophosphorous acid, phosphorous acid, or phosphate. However, PH3 has low physical solubility in water, and the reaction is often affected by gas-liquid mass transfer and oxidant concentration. Strong oxidant consumption, salt accumulation, equipment corrosion, and byproduct control increase the operating load.

[0005] CN101045195A discloses a method for absorbing PH3-containing tail gas using a mixed catalytic solution containing copper and palladium, and sending the absorbent to an oxidation tower for air regeneration to convert phosphorus, copper, palladium, and low-valent phosphorus species. In this method, catalysis and absorption mainly occur in the liquid phase, requiring treatment of metal ions, precipitation, and absorbent regeneration. CN104941422A discloses a method for treating PH3 using an absorbent composed of hydrogen peroxide and sulfuric acid, and utilizing perforated plates and foam layers to enhance gas-liquid contact. This method relies on an oxidant and an acidic absorbent. CN101811064A discloses the use of two or more metals, such as iron, copper, zinc, silver, and cerium, supported on zeolites, activated carbon, or alumina to improve the efficiency of hydrogen peroxide absorption of PH3; its essence remains a multiphase absorption oxidation process involving a catalyst.

[0006] Another type of technology involves oxidizing PH3 on the surface of a solid catalyst first. EP0349768B1 discloses oxidizing PH3-containing waste gas by passing it through a catalyst with a relatively positively charged metal surface at 50~350℃, preferably 150~300℃. CN101972604B discloses heating stored PH3-containing gas to 80~110℃ and passing it through a catalyst, causing the generated phosphorus oxides to be adsorbed onto the catalyst surface, and then regenerating it with water to obtain phosphoric acid. Solid-phase catalytic oxidation can reduce the immediate consumption of large amounts of oxidation absorbent, but the generated P2O3, P2O5, or hydrated phosphorus oxides are easily deposited in catalyst channels, low-temperature connecting pipes, and heat exchange surfaces, leading to active site coverage, increased pressure differential, and frequent cleaning; when the catalyst and absorber are set up separately, the residence distance of phosphorus-containing oxidation products between the two units is further increased.

[0007] Publicly available research also indicates that the copper system is active in the oxidation of PH3. Liquid-phase catalytic studies of copper-ammonia complexes achieved high purification levels within the 30–50 °C range, and the redox potential of Cu(II) / Cu(I) was observed to change with PH3 absorption; excessively high temperatures reduced the stability of the complex and the absorption effect. This suggests that the liquid-phase copper system is best suited for low-temperature operation, while the dry oxidation bed requires operation at higher temperatures to avoid condensation; the two units have different suitable temperature windows. Simply setting them up as separate devices would not only fail to utilize their respective temperature windows but also increase the risk of phosphorus-containing intermediate product deposition. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides an integrated PH3 catalytic oxidation-liquid phase absorption treatment method. This method, without relying on complex equipment limitations, reduces oxidant consumption and phosphorus deposition risks in PH3-containing tail gas treatment through oxygen distribution boundary, low-temperature selective catalytic oxidation, rapid absorption of phosphorus oxides, and coordinated control of operating conditions, thereby achieving stable and deep removal of PH3 and recovery of phosphorus resources.

[0009] This application adopts the following technical solution: the present invention provides an integrated treatment method for PH3 catalytic oxidation and liquid phase absorption, comprising the following steps: (1) Pretreatment: Dust removal and demisting of PH3-containing gas are carried out to reduce the impact of particulate matter and droplets on catalytic active sites; when the total volume fraction of H2, CO, CH4 and other combustible gases in the gas is higher than 5.0%, it is first reduced to no more than 5.0% by dilution or pre-oxidation to establish a safety boundary for subsequent oxygen supply.

[0010] (2) Oxygen mixing: Add oxygen-containing gas to the pretreated PH3-containing gas to make the volume fraction of PH3 in the mixed gas 0.0005%~0.30%, the molar ratio of O2 to PH3 2.05~3.50, and the volume fraction of O2 0.05%~4.50. The lower limit of the molar ratio of O2 to PH3 is used to ensure the effective conversion of PH3 to high-valence phosphorus oxides, and the upper limit is used to limit the temperature rise and safety risks caused by excessive oxygen.

[0011] (3) Catalytic oxidation: The mixed gas is subjected to oxidation at 80~180℃ and gas space velocity of 500~5000 h⁻¹. -1 Contact with a supported Cu-Mn composite oxide catalyst under relative ambient pressure of -5 to 30 kPa oxidizes PH3 into P2O5 and P4O3. 10 Phosphorus oxides, primarily composed of hydrated precursors, are used. The aforementioned temperature and space velocity ranges are designed to balance low-temperature reaction rates, selectivity, and mass transfer conditions at the catalyst surface.

[0012] (4) Rapid absorption: The gas obtained from catalytic oxidation is fed into the alkaline circulating absorption process within 0.1~2.0 s, at 15~45℃, pH 8.0~11.5 and liquid-to-gas ratio of 0.5~8.0 L / m 3 Phosphorus oxides are absorbed under certain conditions to obtain a phosphorus-rich absorbent and purified gas. Shortening the residence time of the oxidized gas and maintaining its temperature before entering the absorption step helps reduce the condensation and deposition of phosphorus oxides in the gas phase path.

[0013] (5) Synergistic regulation: Based on the PH3 concentration, O2 concentration, temperature rise during catalytic oxidation, process pressure difference, pH and redox potential of the absorbent before and after catalytic oxidation, adjust the amount of oxygen-containing gas added, catalytic oxidation temperature, absorbent replenishment amount and phosphorus-rich absorbent discharge amount; when the process pressure difference or outlet PH3 concentration reaches the preset trigger condition, stop oxygen supply, perform short-term liquid cleaning of catalyst, and then purge with inert gas and resume operation.

[0014] Further, the oxygen-containing gas in step (2) is selected from one or more of air, oxygen-enriched air, and a mixture of oxygen and inert gas; preferably, the volume fraction of PH3 in the mixture is 0.001% to 0.15%, the molar ratio of O2 to PH3 is 2.10 to 2.80, and the volume fraction of O2 is 0.10% to 2.50%.

[0015] Further, in step (2), the initial amount of oxygen-containing gas added is calculated based on the inlet concentration of PH3 and the gas flow rate, and feedback correction is performed using the residual O2 concentration after catalytic oxidation and the outlet PH3 concentration. When the volume fraction of O2 exceeds 4.50%, the temperature rise during the catalytic oxidation process exceeds 40°C, or the total volume fraction of combustible gases exceeds 5.0%, the addition of oxygen-containing gas is stopped and inert gas purging is initiated.

[0016] Furthermore, the supported Cu-Mn composite oxide catalyst uses one or more of porous SiC, cordierite, or alumina as a support, with the Cu-Mn composite oxide loading being 5% to 30% of the total catalyst mass, the molar ratio of Cu to Mn being 0.25 to 2.0, and containing 0.1% to 5.0% of one or more promoters selected from Ce, Zr, La, Co, or Fe. The Cu-Mn component is used to form synergistic redox active sites, the heat-resistant support is used to disperse the active component and improve mass transfer, and the promoters are used to adjust the lattice oxygen migration ability and water resistance stability.

[0017] Furthermore, the catalyst is prepared by an equal-volume impregnation method: the support is impregnated in a precursor solution containing Cu, Mn and optional additives, allowed to stand or sonicate for 0.5-4 h, dried at 80-130℃, and then calcined at 300-550℃ for 2-6 h; before use, it is activated at 120-250℃ for 0.5-3 h in a nitrogen atmosphere or an atmosphere containing 0.5%-5.0% oxygen.

[0018] Furthermore, the catalytic oxidation temperature in step (3) is preferably 100~160℃, and 10~40℃ higher than the dew point of the mixed gas, and the gas space velocity is preferably 1000~3000 h⁻¹. -1 The gas obtained from catalytic oxidation is kept at 60~160℃ before entering step (4). By maintaining the reaction temperature above the dew point, the covering and blockage caused by the co-condensation of water vapor and phosphorus oxides can be reduced.

[0019] Further, the alkaline circulating absorbent in step (4) contains one or more of NaOH, KOH, Na2CO3, K2CO3, or ammonia water at a concentration of 0.05–1.0 mol / L, and optionally contains 0.05%–2.0% H2O2 by mass; the redox potential of the absorbent is controlled at 100–500 mV, and the absorption contact time is 0.5–10 s. The alkaline component is used to neutralize and fix phosphorus oxides, and the oxidizing component is used to promote the conversion of phosphite to phosphate.

[0020] Furthermore, when the pressure difference in the catalytic oxidation process increases by 20%–80% relative to the stable operating value, or the outlet pH3 concentration increases by 20%–100% relative to the stable operating value, a short-term liquid purging is triggered. Each purging lasts 2–20 seconds, and the amount of purging liquid used is 0.05–0.50 times the apparent contact space volume of the catalyst. This is followed by purging with inert gas for 30–300 seconds, with an interval of 30–240 minutes between adjacent purgings. This operation is used to dissolve and remove phosphorus-containing deposits in situ and to avoid the formation of an oxygen-containing combustible mixture during the purging stage.

[0021] Further, the phosphorus-rich absorbent is discharged when the phosphate concentration (P) in the absorbent reaches 20-200 g / L, and an equal volume of fresh alkaline absorbent is added. The absorbent is preferably controlled at 20-40℃ and pH 8.5-10.5. The phosphorus-containing solution obtained from short-term liquid washing is added to the phosphorus-rich absorbent, and then the phosphate is recovered through solid-liquid separation, concentration, crystallization, or a combination of two or more of these methods.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects: (1) A safe oxidation boundary of "combustible component pre-control - quantitative oxygen supply - low temperature catalysis" was established. The oxygen supply was constrained by three parameters: the total volume fraction of combustible gases, the molar ratio of O2 to PH3, and the volume fraction of O2. This ensured the effective oxygen required for PH3 oxidation, while limiting excessive oxygen and abnormal temperature rise, without relying on specific mixing or reaction equipment.

[0023] (2) A time-temperature synergy between gas-phase selective oxidation and liquid-phase rapid capture is formed. Catalytic oxidation is carried out at 80~180℃. After oxidation, the gas enters the alkaline absorption process at 15~45℃ within 0.1~2.0 s, so that PH3 is first converted into easily absorbed phosphorus oxides and then rapidly fixed as phosphate, reducing the large consumption of oxidant in direct wet treatment.

[0024] (3) By combining the control of dew point difference, gas space velocity and heat preservation range before absorption, the premature condensation of water vapor and phosphorus oxides in the post-oxidation path is suppressed, the mass transfer deterioration and operation fluctuation caused by phosphorus deposition are reduced, and the adaptability of the method to high humidity or concentration fluctuation tail gas is enhanced.

[0025] (4) A feedback control and trigger-based short-term cleaning based on outlet PH3, residual O2, temperature rise and process pressure difference is proposed. This strategy only implements cleaning when the activity or mass transfer state deviates from the stable range. Combined with the suspension of oxygen supply and inert gas purging, it can reduce the thermal shock, loss of active components and increase in waste liquid caused by continuous spraying, and extend the stable operation cycle.

[0026] (5) The absorbent is controlled by pH, redox potential, liquid-to-gas ratio and phosphorus concentration. The phosphorus-containing cleaning solution and the phosphorus-rich absorbent are combined and recycled, so that pollutant removal and phosphorus resource utilization are closed in the same method chain. Compared with the simple combustion or end oxidation absorption route, it can reduce the risk of secondary pollution and improve the subsequent utilization value of phosphorus-containing by-products. Detailed Implementation Example 1

[0027] After dust removal and demisting, the simulated exhaust gas containing PH3 had a total volume fraction of 1.2% for H2, CO, and CH4. The volume fraction of PH3 was adjusted to 0.0005%, and air was added to achieve a molar ratio of O2 to PH3 of 2.05 and an O2 volume fraction of 0.05%. The mixture was then subjected to a gas hourly space velocity (GHSV) of 500 h⁻¹ at 80°C. -1 The catalyst was contacted with a Cu-Mn / Al2O3 catalyst with a loading of 15% and a Cu / Mn molar ratio of 1.0 under relative ambient pressure of 0 kPa. The oxidized gas was then introduced into a system at 15°C, pH 8.0, and a liquid-to-gas ratio of 0.5 L / m³ within 0.8 s. 3 The absorption solution was 0.10 mol / L NaOH, and the absorption contact time was 4 s. The pH3 conversion rate in the catalytic oxidation section was approximately 97.8%, and the pH3 mass concentration in the purified gas was approximately 0.008 mg / m³. 3 The recovery rate of phosphorus entering the absorbent is approximately 91.5%, and the maximum temperature rise during the process is 6°C. Example 2

[0028] The simulated exhaust gas containing PH3 had a PH3 volume fraction of 0.050% and a total combustible gas volume fraction of 2.0%. Oxygen-enriched air was added to achieve a PH3 molar ratio of 2.50 and an O2 volume fraction of 0.30%. The mixture was heated at 120°C and a gas hourly space velocity (GHSV) of 2000 h⁻¹. -1 The catalyst was contacted with a Cu-Mn-Ce / SiC catalyst under a relative ambient pressure of 5 kPa. The catalyst had an active component loading of 20%, a Cu / Mn molar ratio of 0.8, and a Ce content of 1.0%. The oxidized gas was then introduced into a reactor at 30°C, pH 9.5, and a liquid-to-gas ratio of 2.0 L / m³ within 0.5 s. 3A composite absorbent of 0.30 mol / L Na₂CO₃ and 0.20% H₂O₂ was used, with the redox potential controlled at 280–350 mV. The pH₃ conversion rate was approximately 99.7%, and the pH₃ concentration in the purified gas was approximately 0.6 mg / m³. 3 The phosphorus recovery rate was approximately 95.2%, and phosphate accounted for approximately 94% of the dissolved phosphorus-containing species in the absorbent. After 40 hours of operation, the process pressure differential increased by 25% relative to the initial value. After a short cleaning of 8 seconds and purging for 90 seconds, the pressure differential recovered to 105% of the initial value, and the outlet pH 3 did not show a significant rebound. Example 3

[0029] The simulated exhaust gas containing PH3 had a PH3 volume fraction of 0.15%. After dilution, the total volume fraction of combustible gases decreased from 6.2% to 4.5%. A mixture of oxygen and nitrogen was added to achieve a molar ratio of O2 to PH3 of 3.00 and an O2 volume fraction of 1.20%. The mixture was then subjected to a gas hourly space velocity (GHSV) of 3000 h⁻¹. -1 The gas was contacted with a Cu-Mn-Zr / SiC catalyst under a relative ambient pressure of 15 kPa. After oxidation, the gas entered a reactor at 35°C, pH 10.0, and a liquid-to-gas ratio of 4.0 L / m³ within 0.3 s. 3 The absorption solution was 0.50 mol / L K₂CO₃, and the absorption contact time was 6 s. The pH₃ conversion rate was approximately 99.5%, and the pH₃ concentration in the purified gas was approximately 6.5 mg / m³. 3 The phosphorus recovery rate is approximately 94.0%, with a maximum temperature rise of 28°C. After the phosphorus-rich absorbent reaches 85 g / L (calculated as P), 20% is discharged and an equal volume of fresh absorbent is added. The discharged phosphorus-rich solution can be concentrated and crystallized to obtain phosphate products. Example 4

[0030] The simulated exhaust gas containing PH3 had a PH3 volume fraction of 0.30% and a total combustible gas volume fraction of 3.8%. A mixture of oxygen and nitrogen was added to achieve a PH3 molar ratio of 3.50 and an O2 volume fraction of 4.50%. The mixture was then subjected to a temperature of 180°C and a gas hourly space velocity (GHSV) of 5000 h⁻¹. -1 The gas was contacted with a Cu-Mn-Ce / cordierite catalyst under a relative ambient pressure of 30 kPa. After oxidation, the gas entered a system at 45°C, pH 11.5, and a liquid-to-gas ratio of 8.0 L / m³ within 0.1 s. 3 The absorption solution was 0.80 mol / L KOH, and the absorption contact time was 1 second. The pH3 conversion rate was approximately 99.2%, and the pH3 concentration in the purified gas was approximately 24 mg / m³. 3 The phosphorus recovery rate is approximately 92.8%, and the maximum temperature rise is 39°C. Example 5

[0031] The treatment process addresses tail gas from phosphorus-containing chemical processes, where the pH 3 volume fraction fluctuates between 0.003% and 0.080%, and the combined volume fractions of H2, CO, and CH4 range from 2.3% to 4.2%. Initial oxygen supply values ​​are calculated based on real-time pH 3 concentration and gas flow rate, with the O2 to pH 3 molar ratio controlled between 2.20 and 2.80. The catalytic oxidation temperature is maintained at 110–140℃, and the gas hourly space velocity (GHSV) at 1500–2500 h⁻¹. -1 The absorbent solution was controlled at 25~35℃, pH 9.0~10.0, and liquid-to-gas ratio 1.5~3.0 L / m³. 3 The average concentration of pH3 in the purified gas was approximately 1.8 mg / m³. 3 The average phosphorus recovery rate is approximately 94.3%. When the process pressure difference increases by 30% or the outlet pH value increases by 50% from the stable value, a short-term cleaning of 5-10 seconds and an inert gas purging of 120 seconds are performed. Comparative Example 1

[0032] Except for omitting steps (2) and (3) and directly introducing the PH3-containing gas into the alkaline absorption process, the other conditions are the same as in Example 2. The total PH3 removal rate is about 72%. In order to improve the removal rate, the mass fraction of H2O2 needs to be increased to more than 2.0% and continuously replenished, and the proportion of phosphite in the absorption liquid increases significantly. Comparative Example 2

[0033] The catalytic oxidation conditions were the same as in Example 2, but the oxidized gas was allowed to remain at ambient temperature for 10 seconds before absorption. After 24 hours of operation, the process pressure differential increased by approximately 65% ​​relative to the initial value, and the pH3 concentration in the purified gas increased from approximately 0.6 mg / m³. 3 It rose to approximately 4.8 mg / m³ 3 Phosphorus recovery rate decreased to approximately 86%. Rapid transfer of 0.1–2.0 s and temperature control before absorption can suppress premature condensation and deposition of phosphorus oxides. Comparative Example 3

[0034] Except for not implementing short-term cleaning based on pressure differential and outlet pH3 changes, the other conditions were the same as in Example 5. After 120 hours of operation, the process pressure differential increased by approximately 90%, and the outlet pH3 concentration rose to 2.4 times the stable value; phosphorus deposits were observed after shutdown.

Claims

1. A method for integrated PH3 catalytic oxidation and liquid-phase absorption treatment, characterized in that, Includes the following steps: (1) Pretreatment: Dust removal and demisting of PH3-containing gas; when the total volume fraction of H2, CO, CH4 and other combustible gases is higher than 5.0%, the total volume fraction is reduced to no more than 5.0% by dilution or pre-oxidation. (2) Oxygen mixing: Add oxygen-containing gas to the pretreated PH3-containing gas to make the volume fraction of PH3 in the resulting mixed gas 0.0005%~0.30%, the molar ratio of O2 to PH3 2.05~3.50, and the volume fraction of O2 0.05%~4.50; (3) Catalytic oxidation: The mixed gas is subjected to oxidation at 80~180℃ and gas space velocity of 500~5000 h⁻¹. -1 Contact with a supported Cu-Mn composite oxide catalyst under relative ambient pressure of -5~30kPa oxidizes PH3 into phosphorus oxides; (4) Rapid absorption: The gas obtained from catalytic oxidation is fed into the alkaline circulating absorption process within 0.1~2.0 s, at 15~45℃, pH 8.0~11.5, and liquid-to-gas ratio of 0.5~8.0 L / m 3 The phosphorus oxides are absorbed under certain conditions to obtain a phosphorus-rich absorbent liquid and a purified gas. (5) Synergistic regulation: Based on the PH3 concentration, O2 concentration, temperature rise during catalytic oxidation, process pressure difference, pH and redox potential of the absorbent before and after catalytic oxidation, adjust the amount of oxygen-containing gas added, catalytic oxidation temperature, absorbent replenishment amount and phosphorus-rich absorbent discharge amount; when the process pressure difference or outlet PH3 concentration reaches the preset trigger condition, stop oxygen supply, perform short-term liquid cleaning of catalyst, and then purge with inert gas and resume operation.

2. The method according to claim 1, characterized in that, The oxygen-containing gas in step (2) is selected from one or more of air, oxygen-enriched air, and a mixture of oxygen and inert gas; the volume fraction of PH3 in the mixture is 0.001%~0.15%, the molar ratio of O2 to PH3 is 2.10~2.80, and the volume fraction of O2 is 0.10%~2.50%.

3. The method according to claim 1, characterized in that, Step (2) Calculate the initial amount of oxygen-containing gas added based on the PH3 inlet concentration and gas flow rate, and make feedback corrections based on the residual O2 concentration after catalytic oxidation and the outlet PH3 concentration; when the O2 volume fraction exceeds 4.50%, the temperature rise during the catalytic oxidation process exceeds 40°C, or the total volume fraction of combustible gases exceeds 5.0%, stop adding oxygen-containing gas and switch to inert gas purging.

4. The method according to any one of claims 1-3, characterized in that, The supported Cu-Mn composite oxide catalyst uses one or more of porous SiC, cordierite, or alumina as a support, the loading of Cu-Mn composite oxide is 5% to 30% of the total mass of the catalyst, the molar ratio of Cu to Mn is 0.25 to 2.0, and contains 0.1% to 5.0% of one or more of Ce, Zr, La, Co, or Fe as an auxiliary agent.

5. The method according to claim 4, characterized in that, The catalyst is prepared by an equal-volume impregnation method: the support is impregnated in a precursor solution containing Cu, Mn and optional additives, allowed to stand or sonicate for 0.5-4 h, dried at 80-130℃, and then calcined at 300-550℃ for 2-6 h; before use, the catalyst is activated at 120-250℃ for 0.5-3 h in a nitrogen atmosphere or an atmosphere containing 0.5%-5.0% oxygen.

6. The method according to claim 1, characterized in that, The catalytic oxidation temperature in step (3) is 100~160℃, which is 10~40℃ higher than the dew point of the mixed gas, and the gas space velocity is 1000~3000 h⁻¹. -1 The gas obtained from catalytic oxidation is kept at 60~160℃ before entering step (4).

7. The method according to claim 1, characterized in that, The alkaline circulating absorbent in step (4) contains one or more of NaOH, KOH, Na2CO3, K2CO3 or ammonia water at a concentration of 0.05~1.0 mol / L, and optionally contains 0.05%~2.0% H2O2 by mass; the redox potential of the absorbent is controlled at 100~500 mV, and the absorption contact time is 0.5~10 s.

8. The method according to claim 1, characterized in that, When the pressure difference in the catalytic oxidation process increases by 20% to 80% relative to the stable operating value, or the outlet pH3 concentration increases by 20% to 100% relative to the stable operating value, the short-term liquid cleaning is triggered. Each cleaning lasts for 2 to 20 seconds, and the amount of cleaning liquid used is 0.05 to 0.50 times the apparent contact space volume of the catalyst. Then, inert gas is used for purging for 30 to 300 seconds, and the interval between two adjacent cleanings is 30 to 240 minutes.

9. The method according to claim 1, characterized in that, Step (4) Discharge the phosphorus-rich absorbent solution when the phosphate concentration (P) reaches 20~200 g / L, and add an equal volume of fresh alkaline absorbent solution; the absorbent solution is preferably controlled at 20~40℃ and pH 8.5~10.

5.

10. The method according to claim 1 or 9, characterized in that, The phosphorus-containing liquid obtained from short-term liquid washing is incorporated into the phosphorus-rich absorption liquid, and then the phosphate is recovered through solid-liquid separation, concentration, crystallization, or a combination of two or more of these methods; the purified gas is discharged or reused after the pH3 in the purified gas meets the requirements for emission or subsequent utilization.