Adipic acid tail gas recovery to produce electronic grade nitrous oxide

Abstract

The application discloses adipic acid tail gas recovery and preparation of electronic grade nitrous oxide, and belongs to the technical field of industrial tail gas resource recovery and electronic special gas preparation. Step one: introducing the nitrous oxide-containing tail gas generated by nitric acid oxidation of cyclohexanol and / or cyclohexanone in the adipic acid production process into a tail gas buffer tank, carrying out heat exchange and temperature reduction, gas-liquid separation and mist removal treatment, and then introducing the tail gas into an alkali washing tower to remove nitric acid mist drops and acidic components, so that first-stage purified gas is obtained; in view of the characteristics that the content of nitrous oxide in the adipic acid tail gas is relatively high but the impurities are complex, a combined process of "front-end mist removal alkali washing, low-temperature oxidation absorption, adsorption pre-purification, pressure swing adsorption enrichment, low-temperature condensation rectification, terminal purification and clean filling" is adopted, so that efficient recovery of nitrous oxide and preparation of electronic grade products are realized.

Description

Technical Field

[0001] This invention belongs to the field of industrial waste gas resource recovery and electronic specialty gas preparation technology, specifically relating to a method and system for recovering adipic acid waste gas to prepare electronic-grade nitrous oxide. Background Technology

[0002] Adipic acid is an important raw material for nylon 66, polyurethane, plasticizers, and other fine chemicals. Industrially, adipic acid is typically produced by oxidizing cyclohexanol and / or cyclohexanone with nitric acid. This process generates a large amount of nitrous oxide-containing tail gas as a byproduct. Nitrous oxide, also known as dinitrous oxide (N₂O), is a greenhouse gas with a strong greenhouse effect, and its direct emission would cause environmental burden. However, nitrous oxide is also a commonly used electronic specialty gas in integrated circuits, flat panel displays, photovoltaics, and semiconductor thin film deposition processes, particularly in chemical vapor deposition, plasma-enhanced chemical vapor deposition, and the preparation of oxide films and silicon oxynitride thin films. Therefore, recovering nitrous oxide from adipic acid tail gas and using it to prepare electronic-grade products offers both environmental benefits and resource utilization value.

[0003] Adipic acid tail gas typically contains nitrous oxide, nitrogen, oxygen, carbon dioxide, nitrogen oxides, water vapor, nitric acid droplets, and trace amounts of organic matter. Compared to purification using crude industrial nitrous oxide as a raw material, adipic acid tail gas has a more complex and fluctuating composition, especially containing nitrogen oxides such as nitric oxide and nitrogen dioxide. Because nitric oxide has low solubility in water, it is difficult to remove it deeply using simple water washing, alkaline washing, or conventional absorption methods. Residual nitrogen oxides not only affect the purity of nitrous oxide but also cause corrosion, adsorbent failure, and product performance fluctuations during subsequent compression, condensation, distillation, and filling processes.

[0004] Existing exhaust gas treatment technologies often employ thermal decomposition, catalytic decomposition, or combustion to destroy nitrous oxide. While these methods reduce emissions, they fail to recover high-value resources. Some recovery processes use simple compression, adsorption, or cryogenic condensation to enrich nitrous oxide, but these methods are insufficient for the synergistic removal of nitrogen oxides, moisture, carbon dioxide, organic matter, light components, and particulate matter from adipic acid exhaust gas, making it difficult to consistently obtain electronic-grade nitrous oxide products. In particular, when nitrogen oxides are not deeply removed at the front end, the load on subsequent adsorption beds and distillation columns increases, and the levels of nitrogen oxides, moisture, and acidic impurities in the product are prone to exceed standards. When pressure swing adsorption enrichment or closed-loop utilization of light components is not implemented, cryogenic distillation energy consumption increases, and nitrous oxide recovery rates decrease. When terminal purification and clean filling control are insufficient, the particulate matter and trace impurities in the product fail to meet the requirements for electronic gas use.

[0005] Therefore, there is an urgent need to develop a method for recovering and preparing nitrous oxide that is tail gas with adipic acid. This method would achieve deep removal of nitrogen oxides, efficient enrichment of nitrous oxide, and stable preparation of electronic-grade products through a synergistic combination of front-end low-temperature oxidation absorption, adsorption pre-purification, pressure swing adsorption enrichment, low-temperature condensation distillation, terminal purification, and clean filling. Summary of the Invention

[0006] The purpose of this invention is to provide a method and system for recovering adipic acid tail gas to prepare electronic-grade nitrous oxide, in order to solve the problems of resource waste caused by the direct emission of nitrous oxide from adipic acid tail gas, the difficulty of deep removal of nitrogen oxides and trace impurities by conventional recovery processes, the high energy consumption of low-temperature distillation, and the insufficient stability of electronic-grade nitrous oxide products.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing electronic-grade nitrous oxide by recovering adipic acid tail gas, comprising the following steps: Step 1: The nitrous oxide-containing tail gas generated during the oxidation of cyclohexanol and / or cyclohexanone by nitric acid in the production of adipic acid is introduced into the tail gas buffer tank. After heat exchange and cooling, gas-liquid separation and demisting treatment, it is passed into the alkaline scrubbing tower to remove nitric acid droplets and acidic components, and the first-stage purified gas is obtained.

[0008] Step 2: The primary purified gas is sent to the low-temperature oxidation absorption unit, where nitric oxide is oxidized to high-valence nitrogen oxides, and the nitrogen oxides are removed by absorption in an alkaline peroxide absorption liquid. Then, it is treated by an oxidant decomposition bed to obtain secondary purified gas.

[0009] The low-temperature oxidation absorption unit is the core impurity removal unit used to convert sparingly soluble nitric oxide in the primary purified gas into absorbable high-valence nitrogen oxides. By converting sparingly soluble nitric oxide into nitrogen dioxide, nitrate, or nitrite forms that are easily absorbed by alkaline peroxide absorbent, the nitrogen oxide load can be significantly reduced before entering the compression, adsorption, and distillation processes, thus avoiding subsequent adsorbent poisoning, equipment corrosion, and excessive nitrogen oxide levels in the product.

[0010] Step 3: The secondary purified gas is compressed using an oil-free compressor, and after cooling, condensate separation and precision filtration, it is sequentially passed through a deacidification and dehydration adsorption bed, a dehydrocarbonization adsorption bed and a decarbonization adsorption bed to remove moisture, carbon dioxide, residual acidic gases and volatile organic compounds, thus obtaining pre-purified tail gas.

[0011] Step 4: Pass the pre-purified exhaust gas into the pressure swing adsorption enrichment unit, so that nitrous oxide is selectively adsorbed on the adsorbent and desorbed by depressurization to obtain nitrous oxide enriched gas. The unadsorbed gas is returned to the exhaust gas buffer tank through the nitrous oxide recovery branch or discharged after exhaust gas treatment.

[0012] Step 5: After compressing the nitrous oxide enriched gas to liquefaction pressure, it is sent to the low-temperature condensation distillation unit. Light components such as nitrogen, oxygen and argon are removed through partial condensation and distillation separation. Carbon dioxide, heavy hydrocarbons and condensable heavy components are removed through the bottom drain of the column to obtain high-purity liquid nitrous oxide.

[0013] Step 6: High-purity liquid nitrous oxide is vaporized, terminally purified, filtered into particles, and cleanly filled to obtain electronic-grade nitrous oxide product.

[0014] Furthermore, the nitrous oxide-containing exhaust gas contains 15-45% nitrous oxide by volume, 35-70% nitrogen by volume, 1-12% oxygen by volume, 0.05-5% carbon dioxide by volume, and 50-5000 ppmv of nitrogen oxides, and the temperature of the nitrous oxide-containing exhaust gas before entering the exhaust gas buffer tank is 40-90°C.

[0015] Furthermore, in step one, the temperature of the gas after heat exchange and cooling is 5-25℃; the gas-liquid separation and demisting treatment adopts at least two combinations of cyclone separator, wire mesh demister and fiber demister; the absorbent in the alkaline washing tower is one or more aqueous solutions of sodium hydroxide, sodium carbonate or sodium bicarbonate, and the pH of the absorbent is controlled at 8.5-11.5 so that the nitric acid mist droplet content in the primary purified gas is not higher than 1mg / m³.

[0016] Further, in step two, the low-temperature oxidation absorption unit includes an oxidation section, an absorption section, and an oxidant removal section; the oxidation section uses ozone, hydrogen peroxide atomized liquid, or a combination of ozone and hydrogen peroxide atomized liquid, and the oxidant dosage is 0.8-1.5 times the theoretical amount based on the molar amount of nitrogen oxides; the alkaline peroxide absorption liquid is an aqueous solution containing 0.5-5 wt% hydrogen peroxide and 0.5-8 wt% carbonate, with an absorption temperature of 5-35℃ and a pH controlled at 7.5-10.5; the oxidant removal section is filled with manganese dioxide, activated carbon, or manganese-copper composite oxide to ensure that the nitrogen oxide content in the secondary purified gas is not higher than 1 ppmv and the residual ozone content is not higher than 0.05 ppmv.

[0017] Furthermore, in step three, the outlet pressure of the oil-free compressor is 0.6-1.8 MPa, and the compressed gas is cooled to 5-20°C before entering the adsorption bed; the deacidification and dehydration adsorption bed is composed of activated alumina and 4A molecular sieve, the dehydrocarbonation adsorption bed is composed of one or more of coconut shell activated carbon, hydrophobic silica-alumina molecular sieve or carbon molecular sieve, and the decarbonation adsorption bed is composed of one or more of 13X molecular sieve, modified alumina or sodium zeolite, so that the water dew point of the pre-purified tail gas is not higher than -70°C, the carbon dioxide content is not higher than 10 ppmv, and the total hydrocarbon content is not higher than 5 ppmv.

[0018] Further, in step four, the pressure swing adsorption enrichment unit includes at least two adsorption towers operating alternately, the adsorbent being microporous activated carbon, carbon molecular sieve, hydrophobic molecular sieve, or a combination thereof; the adsorption pressure is 0.3-1.2 MPa, the adsorption temperature is 0-35℃, the desorption pressure is 5-60 kPa, and the volume fraction of nitrous oxide in the desorbed nitrous oxide enriched gas is 60-92%; the regeneration gas of the adsorption tower is the tail gas of light components discharged from the low-temperature condensation distillation unit in step five and / or a small amount of return gas of electronic-grade nitrous oxide product.

[0019] Further, in step five, the low-temperature condensation distillation unit includes a precooling heat exchanger, a partial condenser, a light component distillation column, and a heavy component remover. The nitrous oxide enrichment gas is compressed to 1.2-3.0 MPa and then precooled to -40°C to -85°C. It enters the partial condenser to form a gas-liquid two-phase system. The liquid phase is sent to the light component distillation column, which has 15-45 theoretical plates and a reflux ratio of 0.5-5.0. Light components containing nitrogen, oxygen, and argon are discharged from the top of the column, and liquid nitrous oxide is obtained from the bottom of the column. The liquid nitrous oxide is then intermittently or continuously discharged as sludge by the heavy component remover, with a discharge rate of 0.05-2.0 wt% of the feed rate. A portion of the discharged light components containing nitrogen, oxygen, and argon is used as regeneration gas for the pressure swing adsorption enrichment unit described in step four, for the regeneration of the adsorption column.

[0020] Further, in step six, the terminal purification includes low-temperature adsorption purification and room-temperature precision purification. The temperature for low-temperature adsorption purification is -80℃ to -20℃, and the adsorbent is activated carbon, 5A molecular sieve, 13X molecular sieve, or a combination thereof. The adsorbent for room-temperature precision purification is high-purity alumina, metal oxide modified molecular sieve, or dehydrated and activated silica-alumina molecular sieve. The particle filtration uses a sintered metal filter element or a polytetrafluoroethylene filter element with a pore size of 0.003-0.05μm. The clean filling uses an electronic gas cylinder that has undergone vacuuming, replacement, and drying.

[0021] Furthermore, the volume fraction of electronic-grade nitrous oxide obtained by the above method is not less than 99.998%, preferably not less than 99.999%, and more preferably not less than 99.9995%; wherein the moisture content is not more than 1 ppmv, preferably not more than 0.5 ppmv; the carbon dioxide content is not more than 1 ppmv, preferably not more than 0.5 ppmv; the carbon monoxide content is not more than 1 ppmv, preferably not more than 0.5 ppmv; the nitrogen oxide content is not more than 0.2 ppmv, preferably not more than 0.1 ppmv; the total hydrocarbon content is not more than 1 ppmv, preferably not more than 0.5 ppmv; the oxygen content is not more than 5 ppmv, preferably not more than 1 ppmv; the nitrogen content is not more than 20 ppmv, preferably not more than 5 ppmv; and the number of particles with a particle size greater than 0.1 μm is not higher than the limit specified in the electronic gas filling specification.

[0022] This invention also provides a system for recovering adipic acid tail gas to prepare electronic-grade nitrous oxide for implementing the above-described method, comprising, in sequence, a tail gas buffer tank, a heat exchange cooler, a gas-liquid separator, a demister, an alkaline scrubbing tower, a low-temperature oxidation absorption unit, an oxidant decomposition bed, an oil-free compressor, a cooling separator, an adsorption pre-purification unit, a pressure swing adsorption enrichment unit, a low-temperature condensation distillation unit, a terminal purification unit, a particulate filter, and a clean filling unit; the bottom drain of the low-temperature condensation distillation unit is connected to a heavy component storage tank or a waste gas treatment device, and the light component outlet at the top of the unit is connected to the regeneration gas inlet of the pressure swing adsorption enrichment unit via a valve group; the unadsorbed gas outlet of the pressure swing adsorption enrichment unit is connected to the tail gas buffer tank or the tail gas treatment device.

[0023] Compared with the prior art, the present invention provides a method for recovering adipic acid tail gas to prepare electronic-grade nitrous oxide, which has the following beneficial effects: In view of the characteristics of high nitrous oxide content and complex impurities in adipic acid tail gas, a combined process of "front-end demisting alkaline washing, low-temperature oxidation absorption, adsorption pre-purification, pressure swing adsorption enrichment, low-temperature condensation distillation, terminal purification, and clean filling" is adopted to achieve efficient recovery of nitrous oxide and preparation of electronic-grade products.

[0024] This invention places a low-temperature oxidation absorption unit before compression and adsorption, which can convert sparingly soluble nitric oxide into absorbable high-valence nitrogen oxides, reducing the risk of nitrogen oxides entering the subsequent compression, adsorption and distillation systems from the source, and reducing equipment corrosion, adsorbent failure and excessive nitrogen oxides in the product.

[0025] This invention, through the sequential arrangement of deacidification and dehydration adsorption beds, dehydrogenation adsorption beds, and decarbonation adsorption beds, enables the deep removal of moisture, carbon dioxide, acidic impurities, and volatile organic compounds before pressure swing adsorption enrichment, thereby reducing the load on subsequent enrichment and distillation systems and improving product purity and stability.

[0026] This invention employs a pressure swing adsorption enrichment unit to selectively enrich nitrous oxide, thereby increasing the nitrous oxide concentration in the gas entering the low-temperature condensation distillation unit from 15-45% in the tail gas to 60-92%, thus reducing the energy consumption of low-temperature condensation and distillation and improving the system's processing flexibility.

[0027] This invention utilizes a portion of the light components containing nitrogen, oxygen, and argon discharged from the low-temperature condensation distillation unit as regeneration gas for the pressure swing adsorption enrichment unit, thereby achieving closed-loop utilization of internal materials, reducing external regeneration gas consumption, and simultaneously improving the total recovery rate of nitrous oxide.

[0028] This invention, through the coordinated control of light components discharged from the top of the low-temperature distillation column and heavy components discharged from the bottom, can simultaneously reduce the content of nitrogen, oxygen, argon, carbon dioxide, heavy hydrocarbons and condensable impurities, making it easier for high-purity liquid nitrous oxide to meet electronic grade requirements through final purification.

[0029] This invention reduces moisture, particulate matter, and trace impurities introduced during the filling process through low-temperature adsorption purification, room-temperature precision purification, submicron-level particle filtration, and clean filling, enabling the product to stably reach a purity of over 99.998%, and under preferred operating conditions, to achieve gradient purity levels of over 99.999% and 99.9995%. Attached Figure Description

[0030] Figure 1 The curves showing the change in nitrogen oxide content at the outlet of the low-temperature oxidation absorption unit in Example 6 and Comparative Example 1 of the present invention are shown. Figure 2 The NOx breakthrough curves of the low-temperature oxidation absorption unit at different absorption temperatures in Example 6 and Comparative Example 2 of this invention are shown. Figure 3 This is a comparison curve of the volume fraction of nitrous oxide before entering the low-temperature condensation distillation unit between Example 6 and Comparative Example 3 of the present invention; Figure 4 The curves showing the changes in oxygen and nitrogen content in the top light components of the low-temperature condensing distillation column in Example 6 and Comparative Example 3 of this invention are shown. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Please see Figures 1-4 This invention provides a technical solution for recovering adipic acid tail gas to prepare electronic-grade nitrous oxide: In this invention, unless otherwise stated, all percentages are volume fractions or mass fractions, and ppmv represents parts per million by volume. "Nitrous oxide" and "nitrous oxide" refer to the same substance with the molecular formula N₂O.

[0033] In this embodiment of the invention, the adipic acid tail gas originates from the tail gas pipeline used in the production of adipic acid from the oxidation of cyclohexanol and cyclohexanone with nitric acid, and is introduced into a tail gas buffer tank via a main tail gas pipe. The tail gas buffer tank is equipped with pressure balancing and flame-arresting safety accessories. The heat exchanger is a shell-and-tube heat exchanger or a plate heat exchanger, and the refrigerant is circulating cooling water, an aqueous ethylene glycol solution, or chilled brine. The gas-liquid separator is a cyclone separator, and the demister consists of a wire mesh demister and a fiber demister connected in series.

[0034] The alkaline washing tower is a packed tower, with polypropylene Pall rings or stainless steel structured packing. The low-temperature oxidation absorption unit includes an oxidation section, an absorption section, and an oxidant removal section. The oxidation section is equipped with an ozone mixer and / or hydrogen peroxide atomizing nozzles, the absorption section is equipped with an alkaline peroxide absorption liquid circulation system, and the oxidant removal section is filled with manganese dioxide, activated carbon, or manganese-copper composite oxides. The oil-free compressor is a diaphragm compressor, a dry screw compressor, or an oil-free reciprocating compressor. The adsorption pre-purification unit includes a deacidification and dehydration adsorption bed, a dehydrocarbonization adsorption bed, and a carbon dioxide removal adsorption bed. The pressure swing adsorption enrichment unit includes at least two adsorption towers, preferably four or six towers operating sequentially. The low-temperature condensation distillation unit includes a precooling heat exchanger, a partial condenser, a light component distillation tower, and a heavy component remover. The terminal purification unit includes a low-temperature adsorption purifier and a room-temperature precision purifier.

[0035] Test methods 1. For the purity of nitrous oxide, moisture, carbon dioxide, carbon monoxide, nitrogen oxides, total hydrocarbons, oxygen, and nitrogen in the product, testing should be conducted primarily in accordance with the technical requirements and test methods of the current GB / T 14600-2025 "Electronic Gases - Nitrous Oxide". GB / T 14600-2025 is currently in effect, published on April 25, 2025, and will be implemented on November 1, 2025.

[0036] 2. When determining the moisture content using the dew point method, it shall be carried out in accordance with GB / T 5832.2-2016 "Gas analysis - Determination of trace moisture - Part 2: Dew point method".

[0037] 3. Trace amounts of inorganic impurities such as oxygen, nitrogen, carbon monoxide, and carbon dioxide can be determined by helium ionization gas chromatography, referring to GB / T 28726-2012 "Gas Analysis - Helium Ionization Gas Chromatography".

[0038] 4. Particulate matter testing was performed using an online light scattering particle counter, in accordance with GB / T 26570.1-2011 "Determination of Particle Content in Gases - Light Scattering Method - Part 1: Determination of Particle Content in Pipeline Gases".

[0039] 5. The nitrous oxide recovery rate is calculated using the following formula: Nitrous oxide recovery rate = (molar flow rate of nitrous oxide in the product / molar flow rate of nitrous oxide in the feed gas) × 100%.

[0040] 6. Unit energy consumption is calculated using the following formula: Unit energy consumption = Total power consumption of compression, refrigeration, pumping and control systems during stable operation of the unit / Volume of electronic-grade nitrous oxide product, in kWh / Nm³ product.

[0041] Example 1 A method for recovering adipic acid tail gas to prepare electronic-grade nitrous oxide includes the following steps: S1: The tail gas from adipic acid production is introduced into a tail gas buffer tank. The tail gas has a nitrous oxide volume fraction of 15%, a nitrogen gas volume fraction of 70%, an oxygen volume fraction of 12%, a carbon dioxide volume fraction of 5%, and a nitrogen oxide content of 5000 ppmv. The temperature before entering the tail gas buffer tank is 40℃. The tail gas is cooled to 5℃ by heat exchange and then passes sequentially through a cyclone separator, a wire mesh demister, and a fiber demister before entering an alkaline scrubbing tower. The absorbent in the alkaline scrubbing tower is a mixed aqueous solution of sodium hydroxide and sodium carbonate, with the pH controlled at 8.5, yielding a primary purified gas. The nitric acid droplet content in the primary purified gas is no higher than 1 mg / m³.

[0042] S2: The primary purified gas is fed into the low-temperature oxidation absorption unit. The oxidation section uses ozone as the oxidant, with an oxidant dosage of 0.8 times the theoretical amount based on the molar amount of nitrogen oxides. The absorption section uses an alkaline peroxide absorption solution containing 0.5 wt% hydrogen peroxide and 0.5 wt% sodium carbonate, with an absorption temperature of 5°C and a pH controlled at 7.5. The oxidant removal section is filled with manganese dioxide to obtain the secondary purified gas. The nitrogen oxide content in the secondary purified gas is no higher than 1 ppmv, and the residual ozone content is no higher than 0.05 ppmv.

[0043] S3: The secondary purified gas is compressed to 0.6 MPa using an oil-free compressor, cooled to 5°C, and then enters a cooling separator. After precision filtration, it sequentially passes through a deacidification and dehydration adsorption bed, a dehydrogenation adsorption bed, and a decarbonylation adsorption bed. The deacidification and dehydration adsorption bed is filled with activated alumina and 4A molecular sieve at a volume ratio of 1:1, the dehydrogenation adsorption bed is made of coconut shell activated carbon, and the decarbonylation adsorption bed is made of 13X molecular sieve, resulting in pre-purified tail gas.

[0044] S4: The pre-purified tail gas is sent to the pressure swing adsorption enrichment unit. There are four adsorption towers, the adsorbent is microporous activated carbon, the adsorption pressure is 0.3 MPa, the adsorption temperature is 0℃, the desorption pressure is 5 kPa, and the volume fraction of nitrous oxide in the desorbed nitrous oxide enriched gas is 60%.

[0045] S5: The nitrous oxide enrichment gas is compressed to 1.2 MPa, pre-cooled to -40°C by a pre-cooling heat exchanger, and then enters a partial condenser to form a gas-liquid two-phase system. The liquid phase enters the light component distillation column. The light component distillation column has a theoretical number of 15 plates and a reflux ratio of 0.5. The light component containing nitrogen, oxygen, and argon is discharged from the top of the column, and liquid nitrous oxide is obtained from the bottom. The liquid nitrous oxide is continuously bleeded through a heavy component remover at a rate of 0.05 wt% of the feed. A portion of the light component from the top of the column is used as regeneration gas for the pressure swing adsorption enrichment unit.

[0046] S6: High-purity liquid nitrous oxide is vaporized and then enters the terminal purification unit. The low-temperature adsorption purification temperature is -80℃, and the adsorbent is activated carbon. The room-temperature precision purification adsorbent is high-purity alumina. Particle filtration uses a sintered metal filter element with a pore size of 0.003μm. After that, it is cleanly filled using an electronic gas cylinder that has undergone vacuuming, nitrogen replacement and drying to obtain electronic-grade nitrous oxide product.

[0047] Example 2 This embodiment is basically the same as embodiment 1, except that: The adipic acid tail gas contains 22% nitrous oxide, 64% nitrogen, 8% oxygen, 3% carbon dioxide, and 3000 ppmv of nitrogen oxides. Its temperature before entering the tail gas buffer tank is 55°C; the temperature after heat exchange cooling is 10°C; the pH of the alkaline scrubbing tower is controlled at 9.2; the oxidation section uses a combination of ozone and hydrogen peroxide atomized liquid, with the oxidant dosage being 1.0 times the theoretical amount; the alkaline peroxide absorbent contains 1.5 wt% hydrogen peroxide and 2 wt%... Sodium carbonate, absorption temperature 12℃, pH controlled at 8.2; oil-free compressor outlet pressure 0.9MPa; adsorption pressure 0.5MPa, adsorption temperature 10℃, desorption pressure 15kPa, nitrous oxide volume fraction in nitrous oxide enrichment gas 70%; low-temperature condensation distillation pressure 1.6MPa, precooling temperature -55℃, light component distillation column theoretical plate number 22, reflux ratio 1.5, heavy component waste discharge 0.3wt%; particle filter pore size 0.01μm.

[0048] Example 3 This embodiment is basically the same as embodiment 1, except that: The adipic acid tail gas contains 30% nitrous oxide, 55% nitrogen, 6% oxygen, 1.5% carbon dioxide, and 1500 ppmv of nitrogen oxides. Its temperature before entering the tail gas buffer tank is 65°C; the gas temperature after heat exchange cooling is 15°C; the pH of the alkaline scrubbing tower is controlled at 10.0; the oxidant dosage is 1.1 times the theoretical amount; the alkaline peroxide absorption liquid contains 2.5 wt% hydrogen peroxide and 4 wt% carbonate, with an absorption temperature of 20°C and a pH controlled at 9.0; the oil-free compressor outlet pressure is 1.2 MPa, and the compressed gas is cooled to 12°C; the dehydrocarbonation adsorption bed is made of coconut fiber. Shell activated carbon and hydrophobic silica-alumina molecular sieves are packed at a volume ratio of 2:1; the pressure swing adsorption adsorbent is a combination of microporous activated carbon and carbon molecular sieves at a volume ratio of 3:1, with an adsorption pressure of 0.8 MPa, an adsorption temperature of 20℃, a desorption pressure of 30 kPa, and a nitrous oxide volume fraction of 80% in the nitrous oxide enrichment gas; the low-temperature condensation distillation pressure is 2.0 MPa, the pre-cooling temperature is -65℃, the theoretical number of plates in the light component distillation column is 30, the reflux ratio is 2.5, and the heavy component waste discharge is 0.8 wt%; the low-temperature adsorption purification temperature is -50℃, the adsorbent is a combination of activated carbon and 5A molecular sieves, and the particle filter pore size is 0.02 μm.

[0049] Example 4 This embodiment is basically the same as embodiment 1, except that: The adipic acid tail gas contains 36% nitrous oxide, 50% nitrogen, 4% oxygen, 1.0% carbon dioxide, and 800 ppmv of nitrogen oxides. Its temperature before entering the tail gas buffer tank is 75°C; the gas temperature after heat exchange cooling is 18°C; the pH of the alkaline scrubbing tower is controlled at 10.8; the oxidant dosage is 1.25 times the theoretical amount; the alkaline peroxide absorption liquid contains 3.5 wt% hydrogen peroxide and 5 wt% carbonate, with an absorption temperature of 25°C and a pH controlled at 9.5; the oil-free compressor outlet pressure is 1.4 MPa, and the gas is cooled to 15°C after compression; carbon dioxide removal... The adsorption bed is composed of 13X molecular sieve and modified alumina in a volume ratio of 2:1; the pressure swing adsorption adsorbent is carbon molecular sieve, the adsorption pressure is 0.95 MPa, the adsorption temperature is 25℃, the desorption pressure is 40 kPa, and the volume fraction of nitrous oxide in the nitrous oxide enrichment gas is 86%; the low-temperature condensation distillation pressure is 2.4 MPa, the precooling temperature is -72℃, the theoretical number of plates in the light component distillation column is 36, the reflux ratio is 3.5, and the waste discharge of heavy components is 1.2 wt%; the terminal low-temperature adsorption purification temperature is -40℃, and the room-temperature precision purification adsorbent is metal oxide modified molecular sieve with a particle filtration pore size of 0.02 μm.

[0050] Example 5 This embodiment is an embodiment of the upper end point of the numerical range of the claims, and the specific steps are as follows: S1: The tail gas from adipic acid production is introduced into a tail gas buffer tank. The tail gas has a nitrous oxide volume fraction of 45%, a nitrogen volume fraction of 35%, an oxygen volume fraction of 1%, a carbon dioxide volume fraction of 0.05%, and a nitrogen oxide content of 50 ppmv. The temperature before entering the tail gas buffer tank is 90℃. The tail gas is cooled to 25℃ by a heat exchanger and then passes sequentially through a cyclone separator, a wire mesh demister, and a fiber demister before entering an alkaline scrubbing tower. The absorbent in the alkaline scrubbing tower is a mixed aqueous solution of sodium carbonate and sodium bicarbonate, with the pH controlled at 11.5, resulting in primary purified gas.

[0051] S2: The primary purified gas is fed into the low-temperature oxidation absorption unit. The oxidation section uses a combination of ozone and hydrogen peroxide atomized liquid, with the oxidant dosage being 1.5 times the theoretical amount based on the molar amount of nitrogen oxides; the absorption section uses an alkaline peroxide absorption liquid containing 5 wt% hydrogen peroxide and 8 wt% carbonate, with an absorption temperature of 35℃ and a pH controlled at 10.5; the oxidant removal section is filled with manganese-copper composite oxide to obtain the secondary purified gas.

[0052] S3: The secondary purified gas is compressed to 1.8 MPa using an oil-free compressor, cooled to 20°C, and then enters a cooling separator. After precision filtration, it sequentially passes through a deacidification and dehydration adsorption bed, a dehydrogenation adsorption bed, and a decarbonylation adsorption bed. The deacidification and dehydration adsorption bed consists of activated alumina and 4A molecular sieves; the dehydrogenation adsorption bed consists of hydrophobic silica-alumina molecular sieves and carbon molecular sieves; and the decarbonylation adsorption bed consists of 13X molecular sieves and sodium-type zeolite, resulting in pre-purified tail gas.

[0053] S4: The pre-purified tail gas is sent into the pressure swing adsorption enrichment unit. The adsorbent is a combination of hydrophobic molecular sieve and carbon molecular sieve. The adsorption pressure is 1.2 MPa, the adsorption temperature is 35℃, the desorption pressure is 60 kPa, and the volume fraction of nitrous oxide in the desorbed nitrous oxide enriched gas is 92%.

[0054] S5: The nitrous oxide enrichment gas is compressed to 3.0 MPa, pre-cooled to -85°C by a pre-cooling heat exchanger, and then enters a partial condenser. The liquid phase enters the light component distillation column. The light component distillation column has a theoretical number of 45 plates and a reflux ratio of 5.0. The light component containing nitrogen, oxygen, and argon is discharged from the top of the column, and liquid nitrous oxide is obtained from the bottom. The liquid nitrous oxide is continuously bleeded through a heavy component remover at a rate of 2.0 wt% of the feed. A portion of the light component from the top of the column enters the pressure swing adsorption enrichment unit via a valve assembly as regeneration gas for the adsorption column.

[0055] S6: High-purity liquid nitrous oxide is vaporized and then purified at the terminal. The low-temperature adsorption purification temperature is -20℃, and the adsorbent is a combination of activated carbon, 5A molecular sieve and 13X molecular sieve. The room-temperature precision purification adsorbent is a dehydrated and activated silica-alumina molecular sieve. Particle filtration uses a polytetrafluoroethylene filter element with a pore size of 0.05μm. Clean filling uses electronic gas cylinders that have undergone vacuuming, replacement and drying treatment to obtain electronic grade nitrous oxide product.

[0056] Example 6 This embodiment is a preferred pilot-scale embodiment, and the specific steps are as follows: S1: The tail gas from adipic acid production is introduced into a tail gas buffer tank. The tail gas has a nitrous oxide volume fraction of 38%, a nitrogen volume fraction of 47%, an oxygen volume fraction of 5%, a carbon dioxide volume fraction of 0.8%, and a nitrogen oxide content of 600 ppmv. The temperature before entering the tail gas buffer tank is 70℃. The tail gas is cooled to 12℃ by a heat exchanger and then passes sequentially through a cyclone separator, a wire mesh demister, and a fiber demister before entering an alkaline scrubbing tower. The absorbent in the alkaline scrubbing tower is an aqueous sodium carbonate solution with a pH controlled at 10.2, resulting in primary purified gas.

[0057] S2: The primary purified gas is fed into the low-temperature oxidation absorption unit. The oxidation section uses a combination of ozone and hydrogen peroxide atomized liquid, with the oxidant dosage being 1.2 times the theoretical amount based on the molar amount of nitrogen oxides; the absorption section uses an alkaline peroxide absorption liquid containing 3 wt% hydrogen peroxide and 4.5 wt% sodium carbonate, with an absorption temperature of 18℃ and a pH controlled at 9.2; the oxidant removal section is filled with a composite bed of manganese-copper composite oxide and activated carbon to obtain the secondary purified gas.

[0058] S3: The secondary purified gas is compressed to 1.3 MPa using an oil-free diaphragm compressor, cooled to 10°C, and then enters a cooling separator. After passing through a 0.1 μm precision filter, it sequentially passes through a deacidification and dehydration adsorption bed, a dehydrogenation adsorption bed, and a decarbonylation adsorption bed. The deacidification and dehydration adsorption bed consists of activated alumina and 4A molecular sieve in a volume ratio of 1:2; the dehydrogenation adsorption bed consists of coconut shell activated carbon and hydrophobic silica-alumina molecular sieve in a volume ratio of 1:1; and the decarbonylation adsorption bed consists of 13X molecular sieve and modified alumina in a volume ratio of 2:1, resulting in pre-purified tail gas.

[0059] S4: The pre-purified tail gas is passed into a six-tower pressure swing adsorption enrichment unit. The adsorbent is a combination of microporous activated carbon, carbon molecular sieve, and hydrophobic molecular sieve. The adsorption pressure is 0.9 MPa, the adsorption temperature is 18℃, and the desorption pressure is 20 kPa. The volume fraction of nitrous oxide in the desorbed nitrous oxide enriched gas is 88%. A portion of the light components from the top of the distillation column is used as regeneration gas for the adsorption tower, and the other portion is discharged after tail gas treatment.

[0060] S5: The nitrous oxide enrichment gas is compressed to 2.2 MPa, pre-cooled to -70°C by a pre-cooling heat exchanger, and then enters a partial condenser to form a gas-liquid two-phase system. The liquid phase is fed into a light component distillation column. The light component distillation column has a theoretical number of 38 plates and a reflux ratio of 3.0. The light component containing nitrogen, oxygen, and argon is discharged from the top of the column, and liquid nitrous oxide is obtained from the bottom. The liquid nitrous oxide enters a heavy component remover for continuous bleed discharge, with a bleed discharge rate of 0.6 wt% of the feed.

[0061] S6: High-purity liquid nitrous oxide is vaporized and then enters the terminal purification unit. The low-temperature adsorption purification temperature is -45℃, and the adsorbent is a combination of activated carbon and 13X molecular sieve. The room-temperature precision purification adsorbent is a combination of metal oxide modified molecular sieve and high-purity alumina. Particle filtration uses a metal sintered filter element with a pore size of 0.01μm. Clean filling uses electronic gas cylinders that have undergone vacuuming, nitrous oxide replacement, nitrogen replacement and drying to obtain electronic-grade nitrous oxide product.

[0062] Comparative Example 1: Only the oxidation section in the low-temperature oxidation absorption unit was removed. That is, the primary purified gas did not pass through ozone and hydrogen peroxide atomizing liquid for oxidation, but only entered the alkaline absorption liquid for absorption. The remaining steps and parameters were the same as in Example 6.

[0063] Comparative Example 2 was made by adjusting the absorption temperature of the low-temperature oxidation absorption unit from 18°C ​​to 70°C, while the other steps and parameters were the same as in Example 6.

[0064] Comparative Example 3 only eliminated the pressure swing adsorption enrichment unit, allowing the pre-purified exhaust gas to directly enter the low-temperature condensation distillation unit after compression, while keeping the remaining steps and parameters as similar as possible to Example 6.

[0065] In Comparative Example 4, only the light components containing nitrogen, oxygen, and argon discharged from the top of the low-temperature condensation distillation unit were sent to the tail gas treatment device and not used as regeneration gas for the pressure swing adsorption enrichment unit. Instead, purchased high-purity nitrogen was used as the regeneration gas. The remaining steps and parameters were the same as in Example 6.

[0066] Comparative Example 5: only the dehydrogenation adsorption bed was removed. The secondary purified gas directly entered the pressure swing adsorption enrichment unit after passing through the deacidification and dehydration adsorption bed and the decarbon dioxide adsorption bed. The remaining steps and parameters were the same as in Example 6.

[0067] Comparative Example 6 only omits the low-temperature adsorption purification in the terminal purification unit, retaining only room-temperature precision purification, particle filtration, and clean filling; the remaining steps and parameters are the same as in Example 6.

[0068] Performance testing Table 1. Test results of purity and impurity index of products from the examples and comparative examples.

[0069] For reference, the original exhaust gas entering the exhaust gas buffer tank typically contains hundreds to thousands of ppmv of nitrogen oxides, and the moisture and carbon dioxide contents are far higher than the indicators for electronic-grade nitrous oxide products. After treatment by the method of this invention, the nitrogen oxide content in the product can be reduced to 0.04-0.18 ppmv, the moisture content to 0.18-0.86 ppmv, and the carbon dioxide content to 0.18-0.88 ppmv. The contents of these impurities are reduced by about 3-6 orders of magnitude compared to the original exhaust gas, demonstrating the deep purification capability of the method of this invention for the complex impurity system of adipic acid exhaust gas.

[0070] As shown in Table 1, Example 1 uses the lower end of the numerical ranges in the claims, and the purity of nitrous oxide still reaches 99.9984%. The moisture, carbon dioxide, carbon monoxide, nitrogen oxides, total hydrocarbons, oxygen and nitrogen are all controlled within the wide range of requirements for electronic grade products, indicating that the present invention is still feasible under the conditions of low nitrous oxide content and high impurity load in the tail gas.

[0071] Example 3 uses the intermediate region process within the scope of the claims, achieving a nitrous oxide purity of 99.9991%, reducing nitrogen oxides to 0.08 ppmv, and achieving a nitrous oxide recovery rate of 90.0%. This demonstrates that the combination of low-temperature oxidation absorption, adsorption pre-purification, pressure swing adsorption enrichment, and low-temperature condensation distillation can achieve stable 5N-grade product preparation under moderate load conditions.

[0072] Example 5 uses the upper end process within the scope of the claims, achieving a nitrous oxide purity of 99.9995%, with further reductions in moisture, carbon dioxide, nitrogen oxides, and total hydrocarbons. This demonstrates that under conditions of high nitrous oxide content, high enrichment concentration, and strong distillation, the present invention can further obtain a preferred high-purity product.

[0073] Example 6 is a preferred pilot-scale process, achieving a nitrous oxide purity of 99.9996%, moisture content of 0.18 ppmv, carbon dioxide content of 0.18 ppmv, nitrogen oxide content of 0.04 ppmv, total hydrocarbon content of 0.22 ppmv, oxygen content of 0.4 ppmv, nitrogen content of 2.5 ppmv, particle count of 1 / L, a nitrous oxide recovery rate of 94.0%, and a unit energy consumption of 0.84 kWh / Nm³ of product, demonstrating the best overall performance.

[0074] The superior overall performance of Example 6 is attributed to its use of a moderately high N2O concentration feed, optimized oxidant dosage, low-temperature and moderately alkaline oxidation absorption conditions, a highly efficient six-tower pressure swing adsorption enrichment unit, and a reasonable distillation reflux ratio. Furthermore, through closed-loop utilization of light components from distillation and terminal low-temperature adsorption purification, it achieves synergistic optimization of material recovery, energy utilization, and impurity control throughout the entire process. Therefore, Example 6 exhibits superior performance in terms of product purity, nitrous oxide recovery rate, and unit energy consumption.

[0075] Compared with Example 6, Comparative Example 1 only eliminated the oxidation section, which resulted in the insoluble nitric oxide failing to be effectively converted into absorbable high-valence nitrogen oxides. The nitrogen oxide content in the product increased to 25.0 ppmv, and the purity of nitrous oxide decreased to 99.9920%. This shows that the oxidation section in low-temperature oxidation absorption plays an irreplaceable role in the deep removal of nitrogen oxides.

[0076] Compared with Example 6, Comparative Example 2 only increased the low-temperature oxidation absorption temperature to 70°C, and the nitrogen oxide content in the product increased to 1.50 ppmv, while the nitrous oxide recovery rate decreased to 84.0%. This shows that excessively high absorption temperature will reduce the nitrogen oxide absorption efficiency and increase nitrous oxide loss, which is not conducive to the preparation of electronic-grade products.

[0077] Compared with Example 6, Comparative Example 3 only eliminated the pressure swing adsorption enrichment unit, resulting in a lower nitrous oxide concentration entering the low-temperature condensation distillation unit, an increased light component removal load, and oxygen and nitrogen contents increasing to 8.5 ppmv and 27.0 ppmv, respectively. The unit energy consumption increased to 1.78 kWh / Nm³ of product, indicating that pressure swing adsorption enrichment has a significant effect on reducing distillation load, improving purity, and reducing energy consumption.

[0078] Compared with Example 6, Comparative Example 4 only did not utilize the light components from the top of the distillation column as the regeneration gas for the adsorption column. Although the product purity remained at a high level, the nitrous oxide recovery rate decreased from 94.0% to 91.0%, and the unit energy consumption increased from 0.84 kWh / Nm³ product to 1.05 kWh / Nm³ product. This indicates that the closed-loop utilization of light components can improve system integration, reduce external regeneration gas consumption, and improve the nitrous oxide recovery rate.

[0079] Compared with Example 6, Comparative Example 5 only eliminated the dehydrocarbon adsorption bed, and the total hydrocarbon content in the product increased to 12.0 ppmv, while the purity of nitrous oxide decreased to 99.9980%. This indicates that the dehydrocarbon adsorption bed plays a necessary role in the deep removal of volatile organic compounds from adipic acid tail gas and the stability of electronic-grade products.

[0080] Compared with Example 6, Comparative Example 6 only eliminated low-temperature adsorption purification. The moisture and carbon dioxide increased to 1.80 ppmv and 1.60 ppmv, respectively, the particle number increased to 5 particles / L, and the purity of nitrous oxide decreased to 99.9979%. This shows that terminal low-temperature adsorption purification plays an important role in the final removal of trace moisture, carbon dioxide and trace amounts of condensable impurities.

[0081] In summary, Examples 1, 3, and 5 demonstrate that the present invention can achieve the preparation of electronic-grade nitrous oxide within the scope of the claims; Example 6 demonstrates that the present invention can achieve higher purity, lower impurities, higher recovery rate, and lower energy consumption under preferred operating conditions; and it proves that key technical features such as low-temperature oxidation absorption, pressure swing adsorption enrichment, closed-loop regeneration of light components, dehydrocarbon adsorption, and terminal low-temperature adsorption purification make substantial contributions to achieving the technical effects of the present invention.

Claims

1. A method for recovering adipic acid tail gas to prepare electronic-grade nitrous oxide, characterized in that, Includes the following steps: Step 1: The nitrous oxide-containing tail gas generated during the oxidation of cyclohexanol and / or cyclohexanone by nitric acid in the production of adipic acid is introduced into the tail gas buffer tank. After heat exchange and cooling, gas-liquid separation and demisting treatment, it is passed into the alkaline scrubbing tower to remove nitric acid droplets and acidic components, and the first-stage purified gas is obtained. Step 2: The primary purified gas is sent into the low-temperature oxidation absorption unit, where nitric oxide is oxidized to high-valence nitrogen oxides, and the nitrogen oxides are removed by absorption in the alkaline peroxide absorption liquid. Then, it is treated by the oxidant decomposition bed to obtain the secondary purified gas. Step 3: The secondary purified gas is compressed using an oil-free compressor, and after cooling, condensate separation and precision filtration, it is passed sequentially through a deacidification and dehydration adsorption bed, a dehydrogenation adsorption bed and a decarbonation adsorption bed to remove moisture, carbon dioxide, residual acidic gases and volatile organic compounds, to obtain pre-purified tail gas; Step 4: Pass the pre-purified exhaust gas into the pressure swing adsorption enrichment unit, so that nitrous oxide is selectively adsorbed on the adsorbent and desorbed by depressurization to obtain nitrous oxide enriched gas. The unadsorbed gas is returned to the exhaust gas buffer tank through the nitrous oxide recovery branch or discharged after exhaust gas treatment. Step 5: After the nitrous oxide enrichment gas is compressed to the liquefaction pressure, it is sent to the low-temperature condensation distillation unit. Light components such as nitrogen, oxygen and argon are removed by partial condensation and distillation separation. Carbon dioxide, heavy hydrocarbons and condensable heavy components are removed by sludge discharge from the bottom of the column to obtain high-purity liquid nitrous oxide. Step 6: High-purity liquid nitrous oxide is vaporized, terminally purified, filtered into particles, and cleanly filled to obtain electronic-grade nitrous oxide product.

2. The method for recovering adipic acid tail gas to prepare electronic-grade nitrous oxide according to claim 1, characterized in that, The nitrous oxide-containing exhaust gas has a volume fraction of 15-45% for nitrous oxide, 35-70% for nitrogen, 1-12% for oxygen, 0.05-5% for carbon dioxide, and a nitrogen oxide content of 50-5000 ppmv. The temperature of the nitrous oxide-containing exhaust gas before entering the exhaust gas buffer tank is 40-90°C.

3. The method for recovering adipic acid tail gas to prepare electronic-grade nitrous oxide according to claim 1, characterized in that, In step one, the temperature of the gas after heat exchange and cooling is 5-25℃; the gas-liquid separation and demisting treatment adopts at least two combinations of cyclone separator, wire mesh demister and fiber demister; the absorbent in the alkaline washing tower is one or more aqueous solutions of sodium hydroxide, sodium carbonate or sodium bicarbonate, and the pH of the absorbent is controlled at 8.5-11.5 so that the nitric acid mist droplet content in the primary purified gas is not higher than 1mg / m³.

4. The method for recovering adipic acid tail gas to prepare electronic-grade nitrous oxide according to claim 1, characterized in that, In step two, the low-temperature oxidation absorption unit is the core impurity removal unit used to convert sparingly soluble nitric oxide in the primary purified gas into absorbable high-valence nitrogen oxides. It includes an oxidation section, an absorption section, and an oxidant removal section. The oxidation section uses ozone, hydrogen peroxide atomized liquid, or a combination of ozone and hydrogen peroxide atomized liquid, and the oxidant dosage is 0.8-1.5 times the theoretical amount based on the molar amount of nitrogen oxides. The alkaline peroxide absorption liquid is an aqueous solution containing 0.5-5 wt% hydrogen peroxide and 0.5-8 wt% carbonate, with an absorption temperature of 5-35℃ and a pH controlled at 7.5-10.

5. The oxidant removal section is filled with manganese dioxide, activated carbon, or manganese-copper composite oxides to ensure that the nitrogen oxide content in the secondary purified gas is not higher than 1 ppmv and the residual ozone content is not higher than 0.05 ppmv.

5. The method for recovering adipic acid tail gas to prepare electronic-grade nitrous oxide according to claim 1, characterized in that, In step three, the outlet pressure of the oil-free compressor is 0.6-1.8 MPa. The compressed gas is cooled to 5-20°C and then enters the adsorption bed. The deacidification and dehydration adsorption bed is composed of activated alumina and 4A molecular sieve. The dehydrogenation adsorption bed is composed of one or more of coconut shell activated carbon, hydrophobic silica-alumina molecular sieve, or carbon molecular sieve. The decarbonation adsorption bed is composed of one or more of 13X molecular sieve, modified alumina, or sodium zeolite. This ensures that the water dew point of the pre-purified tail gas is not higher than -70°C, the carbon dioxide content is not higher than 10 ppmv, and the total hydrocarbon content is not higher than 5 ppmv.

6. The method for recovering adipic acid tail gas to prepare electronic-grade nitrous oxide according to claim 1, characterized in that, In step four, the pressure swing adsorption enrichment unit includes at least two adsorption towers operating alternately. The adsorbent is microporous activated carbon, carbon molecular sieve, hydrophobic molecular sieve, or a combination thereof. The adsorption pressure is 0.3-1.2 MPa, the adsorption temperature is 0-35℃, the desorption pressure is 5-60 kPa, and the volume fraction of nitrous oxide in the desorbed nitrous oxide enriched gas is 60-92%. The regeneration gas of the adsorption tower is the tail gas of light components discharged from the low-temperature condensation distillation unit in step five and / or a small amount of return gas of electronic-grade nitrous oxide product.

7. The method for preparing electronic-grade nitrous oxide from adipic acid tail gas according to claim 1, characterized in that, In step five, the low-temperature condensation distillation unit includes a precooling heat exchanger, a partial condenser, a light component distillation column, and a heavy component remover. The nitrous oxide enrichment gas is compressed to 1.2-3.0 MPa and then precooled to -40°C to -85°C. It enters the partial condenser to form a gas-liquid two-phase system. The liquid phase is fed into the light component distillation column, which has 15-45 theoretical plates and a reflux ratio of 0.5-5.

0. Light components containing nitrogen, oxygen, and argon are discharged from the top of the column, and liquid nitrous oxide is obtained from the bottom. The liquid nitrous oxide is then intermittently or continuously discharged as sludge by the heavy component remover, with a discharge rate of 0.05-2.0 wt% of the feed. A portion of the discharged light components containing nitrogen, oxygen, and argon is used as regeneration gas for the pressure swing adsorption enrichment unit described in step four, for the regeneration of the adsorption column.

8. The method for preparing electronic-grade nitrous oxide from adipic acid tail gas according to claim 1, characterized in that, In step six, the terminal purification includes low-temperature adsorption purification and room-temperature precision purification. The temperature for low-temperature adsorption purification is -80℃ to -20℃, and the adsorbent is activated carbon, 5A molecular sieve, 13X molecular sieve, or a combination thereof. The adsorbent for room-temperature precision purification is high-purity alumina, metal oxide modified molecular sieve, or dehydrated and activated silica-alumina molecular sieve. The particle filtration uses a sintered metal filter element or a polytetrafluoroethylene filter element with a pore size of 0.003-0.05μm. The clean filling uses an electronic gas cylinder that has undergone vacuuming, replacement, and drying.

9. The electronic-grade nitrous oxide prepared by the method according to any one of claims 1-8, characterized in that, The volume fraction of the electronic-grade nitrous oxide is not less than 99.998%.

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