4n grade acetylene purification method and apparatus

Abstract

The application discloses a 4N electronic grade acetylene purification method and device, wherein the method comprises the following steps: S1, dehydration: acetylene raw gas is introduced into a dehydration adsorption column filled with molecular sieve for dehydration; S2, selective absorption: the acetylene raw gas after the dehydration is qualified, and is introduced into a DMF bubble desorption tank assembly for absorption at a standard flow of 3-5 SLM; S3, desorption: after tail gas enriched with light components is discharged from the top of the tank, the closed bubble tank is gradiently heated, acetylene is desorbed and separated from the DMF liquid phase in a reverse direction, and the desorption gas phase is collected into a buffer tank for pressure stabilization and temporary storage; S4, impurity removal: the desorption gas phase is introduced into a heavy component removal adsorption column filled with activated carbon of coconut shell after being pressurized at room temperature to remove heavy component impurities in the gas phase; and S5, filtration and filling: after the acetylene gas after the impurity removal is pressurized, the acetylene gas is filled after being filtered through a 0.05 mu m precision filter, and 4N electronic grade acetylene products are obtained. The application effectively improves the acetylene material utilization rate, optimizes the production efficiency and stabilizes the production conditions by optimizing the purification process.

Description

Technical Field

[0001] This invention belongs to the field of chemical gas purification technology, specifically relating to a method and apparatus for purifying 4N electronic-grade acetylene. Background Technology

[0002] Electronic-grade acetylene is an essential precursor gas for semiconductor thin film deposition, epitaxial growth, vacuum coating, and photolithography-assisted processes. It has extremely low control thresholds for vapor phase moisture, inorganic light components, low-carbon hydrocarbons, heavy component impurities, and residual organic solvent impurities, making it an indispensable electronic specialty gas category in high-end semiconductor manufacturing. Currently, the mainstream industrial acetylene preparation process in China is the calcium carbide hydrolysis method, which directly produces acetylene with a purity of only 99% (2N). The acetylene gas phase released from dissolved acetylene contains a large amount of moisture and light component impurities such as N2 / O2 / Ar, methane, ethane, ethylene, carbon monoxide, and carbon dioxide, as well as heavy components such as vinylacetylene and nitrous oxide. Simultaneously, a small amount of solvent vapor is also released with the acetylene desorption, making it unsuitable for use in electronic processes.

[0003] In existing publicly available technologies, the process of purifying acetylene by low-temperature absorption and heating desorption using solvents (such as acetone, DMF, ethanol, and methanol) is a well-known prior art. Several published patents (CN121869044A, CN115259987A, CN115246760A, and CN113563151A) fully disclose this process flow. This process relies on the solvent's specific solubility selectivity for acetylene, enriches acetylene under low-temperature conditions, and separates inorganic and light hydrocarbon components by heating desorption. The process is mature, the solvent cost is low, and it has been applied in industrial acetylene refining processes. However, this known process has inherent technical defects that cannot meet the requirements for mass production of 4N electronic-grade acetylene. The defects are mainly twofold: First, the acetylene gas phase desorbed and released in the tank will carry a large amount of solvent vapor, which is difficult to remove by conventional gas-liquid separation. This directly leads to excessive impurities and a low purity limit in the finished acetylene product, failing to meet the standards for electronic-grade 4N gas. Second, based on the solvent desorption and release pattern, the heavy components vinyl acetylene and nitrous oxide are desorbed later in the sequence. To ensure that the solvent can be reused, the downstream material of the heavy components needs to be vented for a long time. During the venting process, a large amount of acetylene is discharged and lost along with the heavy components, resulting in a large amount of material waste and low overall purification capacity and material utilization rate. In addition, conventional single-tank DMF bubbling devices can only absorb and desorb intermittently and cannot be used for continuous mass production. The industry only has atmospheric pressure dehydration adsorption processes, and there is no process development and application of high-pressure coupled coconut shell activated carbon for simultaneous removal of solvent vapor and heavy components. Those skilled in the art have no relevant process technology inspiration.

[0004] In summary, the existing single-tank DMF bubbling desorption process, combined with conventional atmospheric pressure adsorption for impurity removal, cannot simultaneously guarantee the purity and purification efficiency of the acetylene product. The industry urgently needs a new 4N electronic-grade acetylene purification process that can operate continuously, has excellent impurity removal effect, low acetylene loss, and high purification efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for purifying 4N electronic-grade acetylene.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0007] The 4N electronic-grade acetylene purification method includes the following steps:

[0008] S1. Dehydration: The acetylene feed gas is passed into a dehydration adsorption column packed with molecular sieves for dehydration.

[0009] S2. Selective absorption: The dehydrated acetylene feed gas is fed into the DMF bubbling desorption tank assembly at a standard flow rate of 3-5 SLM for absorption.

[0010] S3, Desorption: After the tail gas enriched with light components is discharged from the top of the tank, the bubble tank is sealed and the temperature is gradually increased to cause acetylene to desorb and precipitate from the DMF liquid in the opposite direction. The desorbed gas phase is collected in the buffer tank for temporary storage under pressure.

[0011] S4. Impurity Removal: After being pressurized, the desorbed gas phase is passed through a heavy adsorption column filled with coconut shell activated carbon at room temperature to remove heavy component impurities in the gas phase.

[0012] S5. Filtration and Filling: After the acetylene gas has been purified, it passes through a 0.05μm precision filter and is then pressurized and filled to obtain 4N electronic grade acetylene product.

[0013] Preferably, the performance parameters of coconut shell activated carbon include: iodine value of activated carbon: 800-1000 mg / g; specific surface area: ≥1000 m² / g. 2 / g; regeneration was carried out at a regeneration temperature of 300℃ and a space velocity of 60h. -1 Nitrogen purging for 4 hours. Approximately 1.5 kg of activated carbon is packed into the adsorption column, with an aspect ratio of 30.

[0014] In one or more embodiments of the present invention, the molecular screening in step S1 is performed on 3A molecular sieve, 5A molecular sieve, ZSM-5 zeolite, SAPO zeolite, FER zeolite, β zeolite, and type A zeolite.

[0015] In one or more embodiments of the present invention, during selective absorption in step S2, the final pressure of the internal system is 4-4.5 bar and the system isothermal temperature is -30-40°C.

[0016] In one or more embodiments of the present invention, in step S2, at least two DMF bubbling desorption tanks with equivalent functions are arranged in parallel, wherein each DMF bubbling desorption tank independently has the function of selectively dissolving acetylene in DMF for enrichment or gradient heating to desorb acetylene from the DMF liquid in the opposite direction, and each DMF bubbling desorption tank has an independently provided control valve with an adjustable opening degree for its air inlet passage and exhaust passage.

[0017] In one or more embodiments of the present invention, the gradient heating in step S3 is as follows: after the acetylene desorption pressure decreases to 0.5-1.5 bar and stabilizes for 10-20 min, the heating begins: the heating rate is 3-5 °C / min, and after increasing the temperature by 10 °C, the temperature is maintained for desorption. After the desorption pressure decreases to 0.5-1.5 bar, the aforementioned heating steps are repeated until the temperature reaches the endpoint temperature; the endpoint temperature is 30-40 °C.

[0018] In one or more embodiments of the present invention, the endpoint of the analysis in step S3 is: a temperature of 20°C-40°C and a pressure of 0.5-1.5 bar.

[0019] In one or more embodiments of the present invention, the particle size of the coconut shell activated carbon in step S4 is 5-15 mesh.

[0020] In one or more embodiments of the present invention, the pressurization pressure in step S4 is 1.5-2.5 MPa.

[0021] In one or more embodiments of the present invention, the apparatus for implementing the aforementioned 4N electronic-grade acetylene purification method includes:

[0022] Gas source device, including a raw material gas pipe for outputting acetylene raw material gas;

[0023] A dehydration device includes a first air inlet pipe and a first air outlet pipe connected to a dehydration chamber, the dehydration chamber being filled with dehydration packing material, and the first air inlet pipe being connected to a raw material air pipe;

[0024] The DMF bubbling desorption tank assembly includes several DMF bubbling desorption tanks arranged in parallel. Each DMF bubbling desorption tank with a controlled heating device independently includes a second chamber for containing DMF and a second inlet pipe and a second outlet pipe connected to a first outlet pipe. The end of the second inlet pipe in the second chamber is submerged below the liquid surface, and the end of the second outlet pipe in the second chamber is located at the top of the chamber. Both the second inlet pipe and the second outlet pipe are independently provided with control valves that can control the opening degree of the pipeline.

[0025] An acetylene buffer tank includes a buffer chamber and a third buffer inlet pipe and a third buffer outlet pipe connected to the buffer chamber. The third buffer inlet pipe is connected to a second outlet pipe.

[0026] The membrane press is connected to the third buffer exhaust pipe;

[0027] The deweight adsorption column is connected to the membrane press;

[0028] The filter is connected to the de-gravity adsorption column.

[0029] In one or more embodiments of the present invention, a control system is further included, the control system being at least communicatively connected to the control valve and / or the controlled heating device and / or the membrane press, wherein any DMF bubbling desorption tank is in the following state:

[0030] Absorption state: The controlled heating device is off, the control valves of the second feed pipe and the second discharge pipe are in the open state, and the dehydrated acetylene feed gas is introduced into the DMF in the second chamber for acetylene adsorption, or

[0031] Desorption state: The controlled heating device is turned on and heats up, the control valve of the second feed pipe is in the closed state, the control valve of the second discharge pipe is in the open state, and the DMF enriched with acetylene in the second chamber desorbs acetylene upon heating.

[0032] Compared with existing technologies, the 4N electronic-grade acetylene purification method and apparatus of the present invention address the shortcomings of existing solvent absorption-desorption acetylene purification processes, such as excessive solvent residue, difficulty in removing heavy components, high acetylene loss, low production capacity, and insufficient purity. The method of the present invention retains the mature solvent absorption-desorption front-end process and adds a high-pressure coconut shell activated carbon de-heavy component removal section, simultaneously achieving deep removal of both solvent and heavy component impurities, reducing acetylene loss, improving acetylene purification efficiency, and ensuring stable mass production of 4N electronic-grade acetylene. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of an apparatus for purifying 4N electronic-grade acetylene in one embodiment of the present invention.

[0035] Explanation of key figure labels:

[0036] 1. Raw material cylinder, 2. Dehydration adsorption column, 3. DMF bubbling desorption tank, 4. Acetylene buffer tank, 5. Membrane press, 6. Deweight adsorption column, 7. Filter, 8. Product cylinder. Detailed Implementation

[0037] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments disclosed herein. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0038] To overcome the shortcomings of existing technologies, such as excessive solvent residue, difficulty in removing heavy components, high acetylene loss, low production capacity, and insufficient purity, this invention provides a 4N electronic-grade acetylene purification method, comprising the following steps:

[0039] S1. Dehydration: The acetylene feed gas is passed through a dehydration adsorption column packed with molecular sieves for dehydration; preferably, the molecular sieve packing is about 200g with an aspect ratio of 30; molecular sieve regeneration is carried out at a regeneration temperature of 300℃ and a space velocity of 600h. -1 Nitrogen purging for 4 hours;

[0040] S2. Selective absorption: The dehydrated acetylene feed gas is fed into the DMF bubbling desorption tank assembly at a standard flow rate of 3-5 SLM for absorption.

[0041] S3, Desorption: After the tail gas enriched with light components is discharged from the top of the tank, the bubble tank is sealed and the temperature is gradually increased to cause acetylene to desorb and precipitate from the DMF liquid in the opposite direction. The desorbed gas phase is collected in the buffer tank for temporary storage under pressure.

[0042] S4. Impurity Removal: After being pressurized, the desorbed gas phase is passed through a heavy adsorption column filled with coconut shell activated carbon at room temperature to remove heavy component impurities in the gas phase.

[0043] S5. Filtration and Filling: After the acetylene gas has been purified, it passes through a 0.05μm precision filter and is then pressurized and filled to obtain 4N electronic grade acetylene product.

[0044] Technical effects of the present invention:

[0045] S1 Molecular Sieve Dewatering Pretreatment Section

[0046] The acetylene feed gas from calcium carbide hydrolysis (2N) is passed through an adsorption column packed with 3A / 5A molecular sieves at 3-5 SLM and 4-4.5 bar for dehydration at room temperature. The molecular sieves have an aspect ratio of 30 and a packing weight of approximately 200 g. Regeneration conditions are 300℃ and a nitrogen space velocity of 600 h⁻¹. -1 Blow up for 4 hours.

[0047] Deep dehydration and blocking of side reactions: The raw gas contains 500-1000 ppm water, which is reduced to below 2 ppm after molecular sieve adsorption. Water will cause two negative effects: ① Water is miscible with DMF, reducing the solubility selectivity of DMF for acetylene and increasing solvent loss; ② Trace amounts of water condense and freeze in the low-temperature bubble tank, clogging the aeration pipe and disrupting continuous mass transfer; ③ Water promotes the trace hydrolysis and polymerization of acetylene to generate heavy component impurities. Pre-dehydration can reduce the load of heavy components at the downstream end from the source.

[0048] Molecular sieves selectively adapt to acetylene systems: 3A / 5A molecular sieves only adsorb water molecules and do not adsorb acetylene or light / heavy hydrocarbon components, thus avoiding acetylene material loss; compared with alumina and silica gel dehydration, molecular sieves exhibit lower adsorption capacity decay after regeneration, allowing for long-term recycling and reducing operating costs.

[0049] Stable operating conditions and compatible with the back-end absorption unit: After dehydration, the dry gas enters the low-temperature DMF bubbling tank without condensation interference, ensuring the stability of the constant temperature system at -30-40℃ and avoiding the decrease in acetylene enrichment efficiency caused by water dilution of DMF.

[0050] S2 Dual-Tank Parallel DMF Low-Temperature High-Pressure Selective Absorption Section

[0051] The two DMF bubbling tanks are connected in parallel. Each tank is kept at a constant temperature of -30 to 40°C and a system pressure of 4 to 4.5 bar. The raw material gas is bubbled from the bottom pipe of the tank at a pressure of 3 to 5 slumps. One tank absorbs and the other desorbs alternately.

[0052] Continuous mass production breaks through the bottleneck of single-tank intermittent operation: Traditional single-tank operation can only operate intermittently with "absorption-venting-desorption-cooling", which limits the production capacity; the dual-tank independent control valves switch in time, with one tank enriching acetylene and the other desorbing and discharging, so that the whole set of equipment has no downtime and the production capacity is increased by more than 40%.

[0053] Low temperature and high pressure enhance the selective dissolution of acetylene: Based on the gas-liquid dissolution equilibrium, low temperature and high pressure significantly improve the solubility of acetylene in DMF, while light components such as N2 / O2 / CH4 / CO have extremely low solubility in DMF; the gas phase at the top of the tank continuously discharges the tail gas of light components, which can remove more than 95% of inorganic light impurities in one go, greatly reducing the adsorption load of the downstream activated carbon.

[0054] Simultaneous pre-enrichment of heavy components: The polarity of heavy components such as vinyl acetylene and N2O is matched with that of DMF. They dissolve in large quantities with acetylene and enter the liquid phase, avoiding the direct emission of heavy components with the tail gas and thus preventing the loss of acetylene. The initial recovery rate of raw material acetylene is increased by 15%.

[0055] Independent and controllable pipelines reduce the risk of cross-contamination: Each tank has an independent inlet and outlet regulating valve. During absorption, the inlet of the desorption tank is closed, and during desorption, the outlet of the absorption tank is closed, preventing the tail gas of light components from mixing into the finished desorption gas and ensuring the purity of crude acetylene pre-purification.

[0056] S3 gradient heating staged desorption section

[0057] After the light components at the top of the tank are emptied, the tank is sealed and allowed to stand until it stabilizes at 0.5-1.5 bar for 10-20 minutes. The temperature is increased by 3-5℃ / min, and the temperature is maintained at 10℃ per increase until the pressure drops by 0.5-1.5 bar. The cycle is repeated until the endpoint of 30-40℃. The desorbed gas is then sent to the buffer tank for pressure stabilization.

[0058] Graded analysis significantly reduces acetylene loss: Traditional one-time rapid heating releases a large amount of acetylene instantly, with heavy components and solvents precipitating out simultaneously, resulting in acetylene loss due to exhaust gas. Gradient heating enables stepwise precipitation of components: the low-temperature section preferentially releases dissolved light components, while the acetylene is slowly precipitated by gradual heating. Acetylene is collected only after all light components have been completely discharged. Acetylene loss with exhaust gas is reduced by more than 60%, corresponding to a 7-10% increase in product yield (verifiable by data from comparative examples).

[0059] To mitigate the risk of acetylene explosion, a uniform gradient heating method is used to control the acetylene precipitation rate, ensuring stable fluctuations in the gas phase pressure inside the tank without instantaneous overpressure. This avoids rapid heating that could lead to localized high-concentration polymerization of acetylene, thus improving the stability and safe operation of the unit.

[0060] Buffer tank pressure stabilization and homogenization: Intermittent desorbed gas enters the buffer tank for mixing and pressure stabilization, eliminating gas phase concentration and pressure fluctuations during the desorption process, ensuring constant gas intake conditions for the downstream membrane press, uniform pressurization load on the membrane press, and extending equipment service life.

[0061] S4 High-Pressure Coconut Shell Activated Carbon De-Weighting Section

[0062] Crude acetylene is pressurized to 1.5-2.5 MPa (preferably 2 MPa) using a membrane press and then introduced at room temperature into an adsorption column filled with 10-mesh coconut shell activated carbon (1.5 kg of carbon, aspect ratio 30, iodine value 800-1000 mg / g, specific surface area ≥1000 m² / g). After saturation, acetylene is recovered by nitrogen at room temperature for 60 hours at 300℃. -1 Nitrogen purging for 4 hours for regeneration.

[0063] High-pressure dual-effect removal of DMF solvent and heavy components ensures 4N purity: Under normal pressure, activated carbon has low adsorption capacity for DMF and vinyl acetylene. Under high pressure of 2MPa, based on the adsorption isotherm, the adsorption capacity of activated carbon increases by 3-5 times. Simultaneously, DMF vapor entrained by S3 desorption is removed (down to less than 5ppm), heavy components C4H4 and N2O are removed, making up for the inherent solvent residue defects of the DMF solvent method. This is a key innovative step that existing processes cannot achieve 4N purity.

[0064] Advantages of coconut shell activated carbon material adaptability: 10-mesh coconut shell activated carbon has micropores as its main pore structure, which has strong selectivity for polar heavy components and DMF small molecule solvents; compared with coal-based activated carbon, it has low ash content and will not release metal impurities to pollute electronic special gases, thus meeting the requirements for semiconductor electronic grade impurity control.

[0065] Renewable and recyclable, reducing consumable costs: After adsorption saturation, the adsorbed phase acetylene is recovered by nitrogen gas at room temperature to avoid acetylene being wasted with the regeneration waste gas; after high-temperature nitrogen purging and regeneration, the adsorption capacity of activated carbon is restored to more than 95%, and it can be recycled more than 50 times, which greatly reduces production costs compared with disposable adsorption packing.

[0066] Simplified process for room temperature adsorption: No supporting refrigeration / heating equipment is required. Deep impurity removal can be completed at room temperature after pressurization, reducing energy consumption from alternating heating and cooling. The device requires fewer supporting equipment and is easy to operate and maintain.

[0067] S50.05μm precision filtration + pressurized filling section

[0068] After impurity removal, the acetylene is passed through a 0.05μm precision filter and pressurized for filling to obtain the 4N finished product.

[0069] It traps solid particles to meet the requirements of electronic special gas particle control: activated carbon powder, molecular sieve debris, and pipeline corrosion microparticles can be carried by airflow. The 0.05μm filter element can completely trap submicron-level solid impurities. Semiconductor thin film processes have strict particle control requirements to avoid coating pinholes and epitaxial defects.

[0070] The final homogeneous finished product has stable filling purity: there are no solid impurities after filtration, the components inside the pressurized filling steel cylinder are uniform, the purity fluctuation of each batch of finished product is ≤±0.0005%, and the quality consistency of mass production is high.

[0071] More specifically, the 4N electronic-grade acetylene purification method includes the following steps:

[0072] S1. Pretreatment of raw material gas by molecular sieve dehydration: 2N industrial grade acetylene raw material gas prepared by calcium carbide hydrolysis is used. The operating pressure of the raw material gas pipeline is controlled at 4-4.5 bar. The raw material gas is fed into a dehydration adsorption column filled with columnar 3A molecular sieve at a standard flow rate of 3-5 SLM to dehydrate at room temperature. After treatment, the water content of acetylene gas phase is reduced from 500-1000 ppm to below 2 ppm.

[0073] S2. Low-Temperature High-Pressure DMF Bottom-Insertion Bubbling Selective Absorption: After dehydration, the qualified acetylene feed gas is fed in at a standard flow rate of 3-5 SLM. The gas is bubbled in through the porous bottom-insertion aeration pipe at the bottom of two parallel DMF bubbling desorption tanks that can be switched synchronously for absorption / desorption. The two bubbling tanks have identical structural parameters and can operate independently with time-sharing switching of operating conditions. One tank absorbs while the other desorbs, achieving continuous production. The final pressure of the system inside the bubbling tank is controlled at 4-4.5 bar, and the system constant temperature is -30-40℃. Utilizing the selective dissolution of acetylene by DMF, DMF preferentially adsorbs and enriches acetylene, while simultaneously entraining and adsorbing a small amount of light and heavy component impurities. Light component impurities such as N2, O2, Ar, CO, CO2, methane, ethane, and ethylene in the feed gas are more enriched in the gas phase at the top of the tank, while most vinyl acetylene and nitrous oxide heavy components dissolve in the DMF liquid phase along with acetylene.

[0074] S3. Gradient heating desorption and staged venting: The sealed bubbling tank is heated in a gradient manner to cause acetylene to desorb and precipitate from the DMF liquid in the opposite direction; in the early stage of desorption, the tail gas enriched with light components at the top of the tank is discharged, and the content of N2, O2 and CH4 impurities in the tail gas is monitored by online gas chromatography. After the impurity detection is qualified, the desorbed gas phase is collected in a buffer tank for temporary storage under pressure. The endpoint temperature of the desorption is 30℃-40℃ and the pressure is 0.5-1.5 bar.

[0075] S4. High-pressure coconut shell activated carbon dual-effect impurity removal: Acetylene gas phase inside the buffer tank is pressurized and stabilized to 2MPa by a diaphragm membrane press, and then introduced into a heavy adsorption column filled with coconut shell activated carbon at room temperature. Under high pressure, coconut shell activated carbon selectively adsorbs and removes heavy component impurities in the gas phase, such as vinyl acetylene, nitrous oxide, and DMF solvent vapor.

[0076] S5. Precision filtration and filling: After the acetylene gas has been purified, it passes through a 0.05μm precision filter to remove solid particulate impurities, and is then pressurized and filled to obtain 4N electronic grade acetylene product with a purity of ≥99.99%.

[0077] In the embodiments section, the following embodiments are based on...

[0078] Industrial acetylene feed gas produced by the hydrolysis of calcium carbide was selected. The parameters of each component of the feed gas are shown in Table 1. The feed gas constant feed flow rate is 3SLM. Two parallel DMF bubbling desorption tanks are set up. Three parallel implementation examples are set up. The feed gas inlet conditions of the three examples are the same. Only the process parameters are slightly adjusted. After dehydration by 3A molecular sieve, the moisture content of the acetylene gas phase in the three examples is controlled to be less than 2ppm.

[0079] Example 1

[0080] The 4N electronic-grade acetylene purification method in this embodiment includes:

[0081] S1. Raw material gas molecular sieve dehydration pretreatment: Control the operating pressure of the raw material gas pipeline to 4.5 bar, the raw material gas inlet flow rate to 3 SLM, the initial water content of the raw material gas to 650 ppm, and pass it into a columnar 3A molecular sieve dehydration adsorption column for adsorption at room temperature. After dehydration, the water content of the acetylene gas phase is 0.8 ppm.

[0082] S2. Low-temperature high-pressure DMF bottom-insertion bubbling selective absorption: Acetylene is introduced through the bottom porous bottom aeration pipe of the No. 1 DMF bubbling desorption tank at a feed flow rate of 3 SLM. The bubbling tank is kept at a constant temperature of -40℃ and a stable pressure of 4.5 bar. DMF selectively dissolves acetylene, enriching the acetylene components. Various inorganic and hydrocarbon light components are enriched and output from the top of the tank. Vinyl acetylene and N2O heavy components are dissolved in the DMF liquid phase. After the enrichment of the No. 1 DMF bubbling desorption tank is completed and the gas inlet is closed, the system switches to the No. 2 DMF bubbling desorption tank to perform selective absorption operation.

[0083] S3. Gradient temperature desorption and staged venting: Let the No. 1 DMF bubbling desorption tank stand at room temperature. After the acetylene desorption pressure drops to 1.5 bar and stabilizes for 10 min, start heating. Increase the temperature uniformly by 10°C at a rate of 3°C / min and maintain this temperature for desorption. After the desorption pressure drops to 1.5 bar, continue to repeat the above heating steps until the temperature reaches the endpoint temperature of 30°C. The system desorption endpoint pressure is 1.5 bar. Acetylene is desorbed and precipitated. The desorbed gas enters the chromatographic analysis. After the light component impurities are detected by online chromatography and meet the standards, the desorbed gas is collected in the buffer tank for pressure stabilization.

[0084] S4. High-Pressure Coconut Shell Activated Carbon Dual-Effect Impurity Removal: Acetylene is pressurized and stabilized to 2.0 MPa using a membrane press, and then passed into an adsorption column filled with 10-mesh commercial coconut shell activated carbon for adsorption at room temperature. The adsorption column contains approximately 1.5 kg of activated carbon with an aspect ratio of 30, an iodine value of 800 mg / g, and a specific surface area of ​​1000 m². 2 / g Targeted removal of vinyl acetylene, nitrous oxide, and DMF solvent vapor; after adsorption saturation, residual acetylene is first purged with nitrogen at room temperature, followed by regeneration with high-purity nitrogen at 300℃ for 4 hours, with a nitrogen space velocity of 60 h⁻¹. -1 ;

[0085] S5. Precision filtration filling: Acetylene is filled under pressure after being filtered through a 0.05μm precision filter to remove particulates.

[0086] Results of this embodiment: The purity of the finished acetylene is 99.9989%, the moisture content is 1.71 ppm, the yield of electronic grade acetylene is 82.25%, and the values ​​of each impurity component correspond to the measured values ​​in Table 1.

[0087] Example 2

[0088] The difference between this embodiment and Embodiment 1 is that:

[0089] S1. Raw material gas molecular sieve dehydration pretreatment: Control the operating pressure of the raw material gas pipeline to 4.0 bar, the raw material gas inlet flow rate to 4 SLM, the initial water content of the raw material gas to 650 ppm, and pass it into a columnar 3A molecular sieve dehydration adsorption column for adsorption at room temperature. After dehydration, the water content of the acetylene gas phase is 1.14 ppm.

[0090] S2. Low-temperature high-pressure DMF bottom-insertion bubbling selective absorption: Acetylene is introduced through the bottom porous bottom aeration pipe of the No. 1 DMF bubbling desorption tank at a feed flow rate of 4 SLM. The bubbling tank is kept at a constant temperature of -35℃ and a stable pressure of 4.0 bar. Relying on the selective dissolution of acetylene by DMF, the acetylene components are enriched. Various inorganic and hydrocarbon light components are enriched and output from the top of the tank. Vinyl acetylene and N2O heavy components are dissolved in the DMF liquid phase. After the enrichment of the No. 1 DMF bubbling desorption tank is completed and the gas inlet is closed, the process is switched to the No. 2 DMF bubbling desorption tank to perform selective absorption operation.

[0091] S3. Gradient temperature desorption and staged venting: Let the No. 1 DMF bubbling desorption tank stand at room temperature. After the acetylene desorption pressure drops to 1.5 bar and stabilizes for 10 min, start heating. Increase the temperature uniformly by 10°C at a rate of 3°C / min and maintain this temperature for desorption. After the desorption pressure drops to 1.5 bar, continue to repeat the above heating steps until the temperature reaches the endpoint temperature of 30°C. The system desorption endpoint pressure is 1.5 bar. Acetylene is desorbed and precipitated. Vent the light component tail gas for the normal time. After online chromatography detects that the impurities meet the standards, the desorbed gas is collected in the buffer tank for pressure stabilization.

[0092] S4. High-pressure coconut shell activated carbon dual-effect impurity removal: The membrane press presses and stabilizes the acetylene to 2.0 MPa, and then passes it into an adsorption column filled with 10-mesh commercial coconut shell activated carbon for room temperature adsorption, specifically removing vinyl acetylene, nitrous oxide, and DMF solvent vapor; after adsorption saturation, residual acetylene is first purged with room temperature nitrogen, and then regenerated by purging with 300℃ high-purity nitrogen.

[0093] S5. Precision filtration filling: Acetylene is filled under pressure after being filtered through a 0.05μm precision filter to remove particulates.

[0094] Results of this embodiment: The purity of the finished acetylene is 99.9985%, the moisture content is 1.72 ppm, the yield of electronic grade acetylene is 78.78%, and the values ​​of each impurity component correspond to the measured values ​​in Table 1.

[0095] Example 3

[0096] The difference between this embodiment and Embodiment 1 is that:

[0097] S1. Raw material gas molecular sieve dehydration pretreatment: Control the operating pressure of the raw material gas pipeline to 4.0 bar, the raw material gas inlet flow rate to 5 SLM, the initial water content of the raw material gas to 650 ppm, and pass it into a columnar 3A molecular sieve dehydration adsorption column for adsorption at room temperature. After dehydration, the water content of the acetylene gas phase is 1.26 ppm.

[0098] S2. Low-temperature high-pressure DMF bottom-insertion bubbling selective absorption: Acetylene is introduced through the bottom porous bottom aeration pipe of the No. 1 DMF bubbling desorption tank at a feed flow rate of 5 SLM. The bubbling tank is kept at a constant temperature of -30℃ and a stable pressure of 4.0 bar. Relying on the selective dissolution of acetylene by DMF, the acetylene components are enriched. Various inorganic and hydrocarbon light components are enriched and output from the top of the tank. Vinyl acetylene and N2O heavy components are dissolved in the DMF liquid phase. After the enrichment of the No. 1 DMF bubbling desorption tank is completed and the gas inlet is closed, the system switches to the No. 2 DMF bubbling desorption tank to perform selective absorption operation.

[0099] S3. Gradient temperature desorption and staged venting: Let the No. 1 DMF bubbling desorption vessel stand at room temperature. After the acetylene desorption pressure drops to 1.5 bar and stabilizes for 10 min, start heating. Increase the temperature uniformly by 10°C at a rate of 3°C / min and maintain this temperature for desorption. After the desorption pressure drops to 1 bar, continue to repeat the above heating steps until the final temperature of 40°C is reached. The final desorption pressure of the system is 1.0 bar. Acetylene is rapidly desorbed and precipitated, shortening the venting time of light components. After online chromatographic detection of impurities meets the standards, the desorbed gas is collected in the buffer tank for pressure stabilization.

[0100] S4. High-pressure coconut shell activated carbon dual-effect impurity removal: The membrane press presses and stabilizes the acetylene to 2.0 MPa, and then passes it into an adsorption column filled with 10-mesh commercial coconut shell activated carbon for room temperature adsorption, specifically removing vinyl acetylene, nitrous oxide, and DMF solvent vapor; after adsorption saturation, residual acetylene is first purged with room temperature nitrogen, and then regenerated by purging with 300℃ high-purity nitrogen.

[0101] S5. Precision filtration filling: Acetylene is filled under pressure after being filtered through a 0.05μm precision filter to remove particulates.

[0102] Results of this embodiment: The purity of the finished acetylene is 99.9985%, the moisture content is 1.85 ppm, the yield of electronic grade acetylene is 74.28%, and the values ​​of each impurity component correspond to the measured values ​​in the table above.

[0103] Example 4

[0104] The only difference between this embodiment and Embodiment 1 is that the gradient step heating parameters are set to 5℃ / min, with a holding temperature of 10℃ per increment, and an endpoint of 35℃ and 1.0 bar.

[0105] Example 5

[0106] The only difference between this embodiment and Embodiment 1 is that the gradient step heating parameters are set to 4℃ / min, with a holding temperature of 10℃ per increment, and an endpoint of 40℃ and 1.5 bar.

[0107] Example 6

[0108] The only difference between this embodiment and Example 1 is that the adsorption parameters in S4 are 2.5 MPa, 10-mesh coconut shell charcoal, and iodine value of 1000 mg / g.

[0109] Example 7

[0110] The only difference between this embodiment and Example 1 is that the adsorption parameters in S4 are 1.5 MPa, 12-mesh coconut shell charcoal, and iodine value of 900 mg / g.

[0111] Table 1 Raw Materials and Product Components of Examples

[0112]

[0113] In summary, the table above shows the following advantages:

[0114] 1. Absorption temperature is negatively correlated with impurities and positively correlated with yield.

[0115] As the absorption temperature increases, the selectivity of DMF for acetylene dissolution decreases, allowing more light components and solvent vapors to enter the downstream phase along with the acetylene. This increases the adsorption load on activated carbon and consequently, the residual DMF level rises. Simultaneously, the high-flow-rate feed shortens the gas-liquid contact residence time, leading to incomplete acetylene enrichment, increased feed loss, and a linear decrease in yield. Under the low-temperature (-40℃) and low-flow-rate 3SLM conditions, gas-liquid mass transfer is sufficient, resulting in optimal acetylene enrichment efficiency, the highest yield, and the lowest solvent impurities, representing the optimal process window.

[0116] 2. Increased desorption endpoint pressure improves impurity removal efficiency.

[0117] The lower the endpoint pressure, the larger the gas phase volume of the system, and the more low-boiling-point heavy components are simultaneously precipitated. At a high endpoint of 1.5 bar, more heavy components remain in the DMF liquid phase, with only a small amount precipitating with acetylene. The removal pressure of activated carbon at the downstream end is lower, resulting in a lower content of heavy components in the finished product. Gradient heating to 30℃ and an endpoint of 1.5 bar balances desorption efficiency and impurity control, and is superior to the 40℃ and 1.0 bar high-temperature, low-pressure desorption scheme.

[0118] 3. Molecular sieve dehydration ensures stable moisture content.

[0119] The molecular sieve section has independent water control and is not affected by fluctuations in absorption and desorption conditions. Even if the feed flow rate is increased to 5SLM, the molecular sieve with an aspect ratio of 30 and a filling amount of 200g still has sufficient adsorption capacity. The moisture content of the finished product does not rise significantly, eliminating the generation of by-product heavy components caused by moisture from the source and ensuring the long-term stability of electronic-grade moisture index.

[0120] 4. The high-pressure activated carbon section is the core of 4N purity.

[0121] Traditional atmospheric pressure solvent desorption processes lack a high-pressure activated carbon stage, resulting in DMF residues typically exceeding 50 ppm, failing to meet 4N electronic grade requirements. This invention adds a 2 MPa high-pressure coconut shell activated carbon adsorption process, utilizing high pressure to enhance adsorption capacity and achieve deep removal of solvent and heavy components in a single step. The finished product purity consistently exceeds 99.9985%, meeting the semiconductor 4N specialty gas standard, representing a core innovative effect that distinguishes it from existing processes.

[0122] Furthermore, based on the gradient operating conditions and measured component data of the three sets of parallel embodiments, it can be seen that within the process range defined by this invention, the lower the bubbling absorption temperature, the smaller the feed flow rate, the higher the desorption endpoint pressure, and the higher the activated carbon adsorption pressure, the better the removal effect of light components, heavy components, and DMF solvent impurities, and the higher the yield of electronic-grade acetylene. The molecular sieve effluent in the three sets of embodiments is consistently below 2 ppm, and the purity of the finished acetylene can reach 99.9985% or higher, all meeting the 4N electronic-grade acetylene usage standard.

[0123] Compared with the prior art, the present invention has the following beneficial effects:

[0124] 1. The process combination is novel: The complete process link of this invention is 3A molecular sieve dehydration + dual tank parallel DMF time-sharing absorption and desorption + staged desorption and venting + high pressure coconut shell activated carbon dual-effect impurity removal. The alternating continuous operation coupled with high pressure activated carbon to remove solvent vapor and heavy components is an integrated purification link that has not been disclosed in existing patents and literature, and its distinguishing technical features are clear.

[0125] 2. Product impurities are controllable and purity meets standards: The purity of the finished acetylene is stable at 99.995%, and the residual vinyl acetylene nitrous oxide and DMF solvent can be controlled within 5ppm. The moisture content is ≤2ppm, and all impurity indicators meet the semiconductor 4N electronic grade acetylene standards.

[0126] 3. Improve acetylene material utilization, optimize production efficiency, and stabilize production conditions.

[0127] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0128] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for purifying 4N electronic-grade acetylene, comprising the following steps: S1. Dehydration: The acetylene feed gas is passed into a dehydration adsorption column packed with molecular sieves for dehydration. S2. Selective absorption: The dehydrated acetylene feed gas is fed into the DMF bubbling desorption tank assembly at a standard flow rate of 3-5 SLM for absorption. S3, Desorption: After the tail gas enriched with light components is discharged from the top of the tank, the bubble tank is sealed and the temperature is gradually increased to cause acetylene to desorb and precipitate from the DMF liquid in the opposite direction. The desorbed gas phase is collected in the buffer tank for temporary storage under pressure. S4. Impurity Removal: After being pressurized, the desorbed gas phase is passed through a heavy adsorption column filled with coconut shell activated carbon at room temperature to remove heavy component impurities in the gas phase. S5. Filtration and Filling: After the acetylene gas has been purified, it passes through a 0.05μm precision filter and is then pressurized and filled to obtain 4N electronic grade acetylene product.

2. The 4N electronic-grade acetylene purification method according to claim 1, characterized in that, The molecular screening in step S1 is performed using 3A molecular sieve, 5A molecular sieve, ZSM-5 zeolite, SAPO zeolite, FER zeolite, β zeolite, and type A zeolite.

3. The 4N electronic-grade acetylene purification method according to claim 1, characterized in that, During the selective absorption described in step S2, the final pressure of the internal system is 4-4.5 bar, and the system isothermal temperature is -30-40℃.

4. The 4N electronic-grade acetylene purification method according to claim 1, characterized in that, In step S2, the DMF bubbling desorption tank assembly is provided in parallel with at least two DMF bubbling desorption tanks having the same function. Each DMF bubbling desorption tank independently has the function of selectively dissolving acetylene in DMF for enrichment or gradient heating to desorb acetylene from the DMF liquid in the opposite direction. The air inlet passage and exhaust passage of each DMF bubbling desorption tank are independently provided with control valves with adjustable opening.

5. The 4N electronic-grade acetylene purification method according to claim 1, characterized in that, The gradient heating in step S3 is as follows: after the acetylene desorption pressure drops to 0.5-1.5 bar and stabilizes for 10-20 min, the heating begins: the heating rate is 3-5℃ / min, and after increasing the temperature by 10℃, the temperature is maintained for desorption. After the desorption pressure drops to 0.5-1.5 bar, the aforementioned heating steps are repeated until the temperature reaches the endpoint temperature, which is 30-40℃.

6. The 4N electronic-grade acetylene purification method according to claim 1, characterized in that, The endpoint of desorption in step S3 is: temperature of 20℃-40℃ and pressure of 0.5-1.5 bar.

7. The 4N electronic-grade acetylene purification method according to claim 1, characterized in that, The particle size of the coconut shell activated carbon mentioned in step S4 is 5-15 mesh.

8. The 4N electronic-grade acetylene purification method according to claim 1, characterized in that, The pressurization pressure in step S4 is 1.5-2.5 MPa.

9. An apparatus for implementing the 4N electronic-grade acetylene purification method according to any one of claims 1-9, comprising: Gas source device, including a raw material gas pipe for outputting acetylene raw material gas; A dehydration device includes a first air inlet pipe and a first air outlet pipe connected to a dehydration chamber, wherein the dehydration chamber is filled with dehydration packing material, and the first air inlet pipe is connected to a raw material air pipe. The DMF bubbling desorption tank assembly includes several DMF bubbling desorption tanks arranged in parallel. Each DMF bubbling desorption tank with a controlled heating device independently includes a second chamber for containing DMF and a second inlet pipe and a second outlet pipe connected to a first outlet pipe. The end of the second inlet pipe in the second chamber is submerged below the liquid surface, and the end of the second outlet pipe in the second chamber is located at the top of the chamber. Both the second inlet pipe and the second outlet pipe are independently provided with control valves that can control the opening degree of the pipeline. An acetylene buffer tank includes a buffer chamber and a third buffer inlet pipe and a third buffer outlet pipe connected to the buffer chamber, wherein the third buffer inlet pipe is connected to a second outlet pipe; The membrane press is connected to the third buffer exhaust pipe; The deweight adsorption column is connected to the membrane press; The filter is connected to the de-gravity adsorption column.

10. The apparatus according to claim 9, characterized in that, It also includes a control system, which is at least communicatively connected to the control valve and / or the controlled heating device and / or the membrane press, wherein any DMF bubbling desorption tank is in the following state: Absorption state: The controlled heating device is off, the control valves of the second feed pipe and the second discharge pipe are in the open state, and the dehydrated acetylene feed gas is introduced into the DMF in the second chamber for acetylene adsorption, or Desorption state: The controlled heating device is turned on and heats up, the control valve of the second feed pipe is in the closed state, the control valve of the second discharge pipe is in the open state, and the DMF enriched with acetylene in the second chamber desorbs acetylene upon heating.

Images