Process for absorbing ethyl acetate in waste gas by using special absorbent

Abstract

The application discloses a process for absorbing ethyl acetate in waste gas by using special absorbent, and belongs to the field of waste gas treatment. The process comprises the following steps: feeding the waste gas containing ethyl acetate into a first absorption tower containing special sodium hydroxide absorption liquid to obtain a first gas containing ethanol and an alkali liquor containing sodium acetate salt; feeding the alkali liquor containing sodium acetate salt into a first circulation tank to form a first circulation absorption liquid; recycling the sodium acetate salt in the first circulation tank and returning the special sodium hydroxide absorption liquid in the first circulation tank to the first absorption tower; feeding the first gas into a second absorption tower containing ethylene glycol aqueous solution to obtain purified gas and a mixed liquid containing ethanol and ethylene glycol; feeding the mixed liquid containing ethanol and ethylene glycol into a desorption tower to desorb ethanol and ethylene glycol solution, recycling the ethanol and returning the ethylene glycol solution to the second absorption tower. The process has high ethyl acetate removal efficiency, the generated ethanol and sodium acetate salt can be recycled, and low-carbon green treatment of waste gas and efficient utilization of resources are realized.

Description

Technical Field

[0001] This invention belongs to the field of volatile organic compound pollution control technology, specifically relating to a process for absorbing ethyl acetate in waste gas using a special absorbent. Background Technology

[0002] Ethyl acetate, as an organic solvent, is widely used in the production of chemicals, pharmaceuticals, coatings, and electronic materials. However, in the manufacturing processes of these industries, ethyl acetate, as a solvent or intermediate, is often emitted with waste gas, forming volatile organic compounds (VOCs) in the waste gas.

[0003] Currently, the technical methods for treating ethyl acetate-containing waste gas include the following categories: 1. Condensation recovery method: Gaseous ethyl acetate is condensed into liquid and collected at low temperature. This method is only suitable for high-concentration (>5000ppm) and small-volume waste gas. It has high energy consumption, and the collected ethyl acetate liquid often contains other impurities. 2. Adsorption recovery method: For example, Chinese invention patent CN120515211A discloses the continuous adsorption of ethyl acetate molecules in waste gas through porous materials (such as activated carbon, molecular sieves, etc.). However, it still has the following defects: (1) The adsorption capacity of activated carbon is limited and it needs to be replaced regularly; (2) Regeneration consumes a lot of energy and generates secondary wastewater; (3) Activated carbon has high requirements for the humidity of waste gas and needs to be dried before adsorption. 3. Combustion method: Ethyl acetate is oxidized and burned (including TO, CO, RTO / RCO) to generate pollution-free CO2, etc. However, the equipment investment and operating costs are high, and safety issues cannot be ignored. 4. Absorption method: Physical or chemical absorption is carried out using liquids (water, organic solvents, etc.). It has low energy consumption, low operation requirements and a wide treatment range (it can treat large volume and low concentration of ethyl acetate waste gas). However, there are problems such as desorption after the absorbent is saturated and waste of resources.

[0004] In recent years, absorption methods have attracted attention due to their low cost, continuous absorption capability, low requirements for waste gas, and wide treatment range. However, the core bottleneck lies in the selection of absorbents and subsequent desorption. An ideal absorbent should possess characteristics such as high selectivity, high absorption capacity, low volatility, and easy separation. High selectivity facilitates efficient absorption of the target gas and avoids the influence of other components on absorption and subsequent processes. Low volatility avoids secondary pollution, and easy separation enables resource recycling.

[0005] According to current technology, tests were conducted on traditional physical absorbents (such as water and organic solvents such as vegetable oils). However, these absorbents have low absorption capacity for ethyl acetate (approximately 8.5 g / 100 ml at room temperature), low absorption efficiency (<80%), require a matching absorbent preparation system, are relatively complex to operate, and have high resource recycling costs. Furthermore, the absorption efficiency is affected by the oxidation and deterioration of vegetable oils during long-term operation.

[0006] Therefore, developing a simple, efficient, low-cost, and recyclable ethyl acetate waste gas treatment process to achieve ultra-low VOC emissions and resource recycling has become the key challenge in the development of this technology. Summary of the Invention

[0007] The purpose of this invention is to provide a process for absorbing ethyl acetate in waste gas using a special absorbent. This process can effectively treat ethyl acetate in waste gas and can be directly applied to industries that generate ethyl acetate waste gas, such as chemical, pharmaceutical, coating, and electronic material production. It also covers the field of industrial waste gas resource recycling, such as the recycling and reuse of sodium acetate and ethanol.

[0008] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution: A process for absorbing ethyl acetate from waste gas using a special absorbent includes the following steps: The waste gas containing ethyl acetate is passed into the first absorption tower containing a special sodium hydroxide absorbent to obtain a first gas containing ethanol and an alkaline solution containing sodium acetate. An alkaline solution containing sodium acetate is fed into a first circulation tank to form a first circulation absorbent; the sodium acetate in the first circulation tank is recovered, and the special sodium hydroxide absorbent in the first circulation tank is returned to the first absorption tower. The first gas is passed into a second absorption tower containing an aqueous solution of ethylene glycol to obtain purified gas and a mixture containing ethanol and ethylene glycol. A mixture containing ethanol and ethylene glycol is fed into a stripping column to strip out ethanol and ethylene glycol solutions. The ethanol is recovered and the ethylene glycol solution is returned to the second absorption column.

[0009] In one or more embodiments of the present invention, in the first absorption tower, the volume of the special sodium hydroxide absorbent is 80L~100L, and the flow rate of the waste gas is 250L / h~300L / h.

[0010] In one or more embodiments of the present invention, in the second absorption tower, the volume of ethylene glycol absorption liquid is 80L~100L, and the flow rate of the first gas is 250L / h~300L / h.

[0011] In one or more embodiments of the present invention, in the first absorption tower, the special sodium hydroxide absorbent is a mixed solution of sodium hydroxide and sodium acetate, wherein the mass fraction of sodium hydroxide is 10%-30% and the mass fraction of sodium acetate is 10%-30%; and / or, In the second absorption tower, the mass fraction of ethylene glycol in the ethylene glycol absorption liquid is 20%-50%.

[0012] In one or more embodiments of the present invention, the mixture containing ethanol and ethylene glycol is fed into a second circulation tank to form a second circulation liquid, and the second circulation liquid is returned to the second absorption tower; when the second absorption tower has been running for 15-20 hours, the mixture containing ethanol and ethylene glycol is fed into a desorption tower for desorption.

[0013] In one or more embodiments of the present invention, a first catalyst bed, a second catalyst bed, and a third catalyst bed are provided sequentially from bottom to top in both the first absorption tower and the second absorption tower; The first catalyst bed is a composite catalyst of activated carbon powder and glass fiber, wherein polyacrylamide is supported on the activated carbon powder; The second catalyst bed is a composite catalyst of activated carbon powder and glass fiber. The activated carbon powder is loaded with silane and polyacrylamide. The silane is at least one of methyltrimethoxysilane, isobutyltriethoxysilane, and hexyltrimethoxysilane. The weight ratio of the silane to the polyacrylamide is 1:(0.8-2). The third catalyst bed is a composite catalyst of activated carbon powder and glass fiber, wherein the activated carbon powder is loaded with octadecyltrimethoxysilane.

[0014] In one or more embodiments of the present invention, with the mass of the polyacrylamide being 5%-10% of the mass of the activated carbon powder, the activated carbon powder is soaked in a polyacrylamide aqueous solution for a certain period of time, and then dried at 60℃-70℃ for 1h-2h to obtain activated carbon powder loaded with polyacrylamide.

[0015] In one or more embodiments of the present invention, activated carbon powder loaded with polyacrylamide and mesoporous silica are mixed with a mass ratio of 1:(0.1-0.3) of activated carbon powder and mesoporous silica, and then adsorption is carried out under vacuum conditions to obtain activated carbon powder loaded with polyacrylamide and mesoporous silica.

[0016] In one or more embodiments of the present invention, the silane and polyacrylamide are dispersed in an aqueous ethanol solution, activated carbon powder is added for soaking, and then dried to obtain activated carbon powder loaded with silane and polyacrylamide.

[0017] In one or more embodiments of the present invention, the octadecyltrimethoxysilane is dispersed in an aqueous ethanol solution, activated carbon powder is added and soaked, and then dried to obtain activated carbon powder loaded with octadecyltrimethoxysilane.

[0018] Compared with existing technologies, the present invention absorbs ethyl acetate using alkaline solution, namely special sodium hydroxide absorbent, which not only improves the removal efficiency of ethyl acetate by utilizing the irreversibility of chemical reactions and successfully avoids the capacity problem of absorbent, but also makes the generated ethanol easier to recycle and has a lower regeneration cost compared to ethyl acetate. Furthermore, the sodium acetate and ethanol generated in the reaction can be recycled as by-products, thus achieving low-carbon green treatment and efficient resource utilization of ethyl acetate waste gas. Attached Figure Description

[0019] 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.

[0020] Figure 1 This is a flowchart of a process for absorbing ethyl acetate from waste gas using a special absorbent, according to one embodiment of the present invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure are described clearly and completely below. 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.

[0022] One specific embodiment of the present invention provides a process for absorbing ethyl acetate from waste gas using a special absorbent, such as... Figure 1 As shown, the specific steps include the following: Step 1: The waste gas containing ethyl acetate is passed into the first absorption tower containing a special sodium hydroxide absorbent to obtain a first gas containing ethanol and an alkaline solution containing sodium acetate.

[0023] Specifically, the sodium hydroxide absorbent is a mixed solution of sodium hydroxide and sodium acetate with a certain mass fraction, wherein the mass fraction of sodium hydroxide is 10%-30% and the mass fraction of sodium acetate is 10%-30%. In this step, the special sodium hydroxide absorbent converts ethyl acetate into ethanol and sodium acetate salt. Sodium acetate salt can be continuously precipitated during the absorption of ethyl acetate, and sodium acetate does not need to be added in subsequent steps.

[0024] The volume of the special sodium hydroxide absorbent is 80L~100L, and the flow rate of the waste gas is 250L / h~300L / h. A suitable gas-liquid ratio and reaction time can maximize the absorption efficiency of the waste gas while controlling energy consumption costs. Specifically, this involves ensuring sufficient contact between the gas and liquid phases to form a stable liquid film, thereby improving the absorption efficiency of ethyl acetate.

[0025] Step 2: The alkaline solution containing sodium acetate is fed into the first circulation tank to form the first circulation absorbent. The sodium acetate in the first circulation tank is recovered and the special sodium hydroxide absorbent is returned to the first absorption tower for recycling.

[0026] Specifically, when the mass fraction of sodium hydroxide in the first circulating absorbent drops to 20%, caustic soda flakes and a certain amount of water are added to replenish it, so that the mass fraction of sodium hydroxide is within the range of 30%, in order to reduce the impact of insufficient sodium hydroxide on the efficiency of ethyl acetate treatment.

[0027] Step 3: The first gas containing ethanol is passed into the second absorption tower containing an aqueous solution of ethylene glycol to obtain purified gas and a mixture containing ethanol and ethylene glycol.

[0028] Specifically, the volume of the ethylene glycol absorbent is 80L~100L, and the flow rate of the first gas is 250L / h~300L / h. In this step, the ethylene glycol absorbent is used to absorb ethanol, which facilitates the recovery of ethanol in subsequent steps for recycling.

[0029] Step 4: The mixture containing ethanol and ethylene glycol is fed into the second circulation tank to form the second circulation liquid, and the second circulation liquid is returned to the second absorption tower.

[0030] Specifically, the second circulating liquid is returned to the second absorption tower to continue processing the first gas.

[0031] Step 5: The mixture containing ethanol and ethylene glycol is fed into the desorption tower to desorb the ethanol and ethylene glycol solutions. The ethanol is recovered and the ethylene glycol solution is returned to the second absorption tower.

[0032] Specifically, after the second absorption tower has been running for 15-20 hours, the mixture is sent to a stripping tower for stripping, where ethanol and a recyclable ethylene glycol solution are separated. The ethanol is recovered, and the ethylene glycol solution is returned to the second absorption tower for recycling. The stripping tower is a distillation tower. Based on the different boiling points of ethanol and ethylene glycol, the ethanol is separated from the mixture by heating the distillation tower.

[0033] The first and second absorption towers used in this invention are both packed towers, with ceramic Pall rings as the packing material. The diameter of the ceramic Pall rings is 15mm~40mm, the height is 0.8-1.2 times the diameter, and the specific surface area is 155m². 2 / m 3 ~230m 2 / m3 The porosity is 70%~85%. The packed tower operates at a temperature of 20℃-35℃ and a pressure of atmospheric pressure, and is equipped with an inertial demister at the top of the tower.

[0034] Furthermore, to ensure that the first gas entering the second absorption tower after treatment with the special sodium hydroxide absorbent contains little or no ethyl acetate, a first catalyst bed, a second catalyst bed, and a third catalyst bed are sequentially arranged above the ceramic Pall rings in both the first and second absorption towers. The first gas enters the second absorption tower after being treated by the first catalyst bed, the second catalyst bed, and the third catalyst bed in the first absorption tower, and then comes into contact with the ethylene glycol absorbent after being treated by the first catalyst bed, the second catalyst bed, and the third catalyst bed in the second absorption tower.

[0035] Specifically, the first catalyst bed, the second catalyst bed, and the third catalyst bed are arranged adjacent to each other in sequence, with a total height of 0.3 to 0.5 times the total height of the absorption tower body. The first catalyst bed, the second catalyst bed, and the third catalyst bed are set at the same height.

[0036] The catalyst bed consists of three layers: a first catalyst bed composed of activated carbon powder and glass fiber, with polyacrylamide supported on the activated carbon powder; a second catalyst bed composed of activated carbon powder and glass fiber, with silane and polyacrylamide supported on the activated carbon powder, wherein the silane is at least one selected from methyltrimethoxysilane, isobutyltriethoxysilane, and hexyltrimethoxysilane, and the weight ratio of silane to polyacrylamide is 1:(0.8-2); and a third catalyst bed composed of activated carbon powder and glass fiber, with octadecyltrimethoxysilane supported on the activated carbon powder.

[0037] Specifically, activated carbon powder has abundant pores and strong adsorption capacity. By treating the activated carbon powder with different materials, the first catalyst bed becomes highly hygroscopic, the second catalyst bed becomes somewhat hygroscopic and hydrophobic, and the third catalyst bed becomes highly hydrophobic. The stronger the hydrophobicity, the better the adsorption effect of the activated carbon powder on ethyl acetate. Therefore, when the first gas passes through the first, second, and third catalyst beds in sequence, the water vapor contained in the first gas is preferentially absorbed in large quantities by the first catalyst bed, the remaining water vapor is further absorbed by the second catalyst bed, and at the same time, the second catalyst bed begins to absorb ethyl acetate. The remaining ethyl acetate is absorbed by the third catalyst bed, thereby achieving the purpose of removing ethyl acetate contained in the first gas, so that the final purified gas contains little or no ethyl acetate.

[0038] In addition, the first catalyst bed, the second catalyst bed, and the third catalyst bed all have excellent water resistance and can be used for a long time.

[0039] Furthermore, the method for treating the activated carbon powder in the first catalyst bed is as follows: taking polyacrylamide as 5%-10% of the activated carbon powder mass, the activated carbon powder is soaked in a polyacrylamide aqueous solution for a certain period of time, and then dried at 60℃-70℃ for 1h-2h to obtain activated carbon powder loaded with polyacrylamide.

[0040] Specifically, polyacrylamide with a molecular weight of 40,000-100,000 can effectively penetrate the internal pores of activated carbon fibers and reduce the possibility of polyacrylamide absorbing water, swelling, and blocking the pores later.

[0041] Furthermore, with a mass ratio of activated carbon powder to mesoporous silica of 1:(0.1-0.3), activated carbon powder loaded with polyacrylamide and mesoporous silica were mixed, and then adsorption was carried out under vacuum conditions to obtain activated carbon powder loaded with polyacrylamide and mesoporous silica. The particle size of the activated carbon powder was 70μm-95μm, and the particle size of the mesoporous silica was 30nm-50nm.

[0042] Specifically, as the first catalyst bed absorbs water vapor, the polyacrylamide may swell to a certain extent, potentially clogging the pores of the activated carbon powder. Besides controlling the quality of the polyacrylamide and activated carbon powder to reduce the possibility of polyacrylamide swelling and pore clogging, loading mesoporous silica can also inhibit polyacrylamide swelling and pore clogging. When polyacrylamide swells, the mesoporous silica prevents further pore clogging by the polyacrylamide. Simultaneously, the pores within the mesoporous silica itself allow the first gas to pass through and exert a certain water absorption effect, thus enabling the first catalyst bed to continuously process the first gas.

[0043] Furthermore, the method for treating the activated carbon powder in the second catalyst bed is as follows: silane and polyacrylamide are dispersed in an ethanol aqueous solution, activated carbon powder is added and soaked, and then dried to obtain activated carbon powder loaded with silane and polyacrylamide.

[0044] Furthermore, the method for treating the activated carbon powder in the third catalyst bed is as follows: octadecyltrimethoxysilane is dispersed in an aqueous ethanol solution, activated carbon powder is added and soaked, then removed and dried to obtain activated carbon powder loaded with octadecyltrimethoxysilane.

[0045] Furthermore, the composite catalysts of activated carbon powder and glass fiber in the first, second, and third catalyst beds were all prepared using the following method: activated carbon powder, glass fiber, silica sol, and water were mixed in a mass ratio of (4-5):(1-2):(0.2-0.4):1 to obtain a slurry. The slurry was sprayed onto a glass fiber membrane and dried at 65℃-75℃ for 20-24 hours to obtain the composite catalyst. The glass fibers had a diameter of 8μm-10μm and a length of 3mm-5mm, and the glass fiber membrane had a thickness of 0.2mm-0.4mm and an areal density of 100g / m³. 2 -150g / m 2 The pore size is 2μm-5μm.

[0046] The present invention will be further described in detail below with reference to specific embodiments.

[0047] The activated carbon powder used in this invention was purchased from Shijiazhuang Hongsen Activated Carbon, with a mesh size of 200; the mesoporous silica was purchased from Suzhou Beike Nano; and the polyacrylamide was purchased from Aladdin, with an average Mn of 40,000.

[0048] Preparation Example 1 Take polyacrylamide and activated carbon powder, with the mass of polyacrylamide being 8% of the mass of activated carbon powder. Dissolve the polyacrylamide in deionized water to prepare an aqueous solution with a mass concentration of 3%. Then add activated carbon powder and soak for 1 hour. After filtration, dry the activated carbon powder at 65°C for 2 hours to obtain activated carbon powder loaded with polyacrylamide.

[0049] A slurry was prepared by mixing activated carbon powder loaded with polyacrylamide, glass fiber, silica sol (SiO2 mass fraction of 38%), and water in a mass ratio of 5:2:0.3:1. The slurry was then sprayed onto a 0.3 mm thick surface with a density of 150 g / m². 2 The slurry and glass fiber membrane were applied in a mass ratio of 3:1. The mixture was then dried at 70°C for 22 hours to obtain the composite catalyst.

[0050] Preparation Example 2 With a mass ratio of activated carbon powder to mesoporous silica of 1:0.2, activated carbon powder loaded with polyacrylamide and mesoporous silica from Preparation Example 1 were taken, mixed, and then placed in a vacuum chamber for vacuum adsorption at a pressure of -0.1 MPa for 5 hours to obtain activated carbon powder loaded with polyacrylamide and mesoporous silica.

[0051] A slurry was prepared by mixing activated carbon powder loaded with polyacrylamide and mesoporous silica, glass fiber, silica sol (SiO2 mass fraction of 38%), and water in a mass ratio of 5:2:0.3:1. The slurry was then sprayed onto a 0.3 mm thick surface with a surface density of 150 g / m². 2The slurry and glass fiber membrane were applied in a mass ratio of 3:1. The mixture was then dried at 70°C for 22 hours to obtain the composite catalyst.

[0052] Preparation Example 3 Methyltrimethoxysilane and polyacrylamide in a mass ratio of 1:1 were dispersed in a 30wt% ethanol aqueous solution, with the concentration of methyltrimethoxysilane being 3wt%. Then, activated carbon powder was added to the solution at a mass ratio of 4% of the activated carbon powder mass to the polyacrylamide mass. The solution was soaked at 60℃ for 1 hour, filtered, and dried at 60℃ for 2 hours to obtain activated carbon powder loaded with silane and polyacrylamide.

[0053] A slurry was prepared by mixing activated carbon powder loaded with silane and polyacrylamide, glass fiber, silica sol (SiO2 mass fraction of 38%), and water in a mass ratio of 5:2:0.3:1. The slurry was then sprayed onto a 0.3 mm thick surface with a surface density of 150 g / m². 2 The slurry and glass fiber membrane were applied in a mass ratio of 3:1. The mixture was then dried at 70°C for 22 hours to obtain the composite catalyst.

[0054] Preparation Example 4 Octadecyltrimethoxysilane was dispersed in a 30 wt% aqueous ethanol solution, with a dispersion concentration of 3 wt%. Then, activated carbon powder was added to the solution at a mass of 4% of the activated carbon fiber mass, and the solution was soaked at 60°C for 1 hour. After soaking, the solution was dried at 60°C for 2 hours to obtain activated carbon powder loaded with octadecyltrimethoxysilane.

[0055] A slurry was prepared by mixing activated carbon powder loaded with octadecyltrimethoxysilane, glass fiber, silica sol (SiO2 mass fraction of 38%), and water in a mass ratio of 5:2:0.3:1. The slurry was then sprayed onto a 0.3 mm thick surface with a surface density of 150 g / m². 2 The slurry and glass fiber membrane were applied in a mass ratio of 3:1. The mixture was then dried at 70°C for 22 hours to obtain the composite catalyst.

[0056] Example 1

[0057] This embodiment describes a process for absorbing ethyl acetate from waste gas using a special absorbent, as detailed below: The air volume is 300L / h and the ethyl acetate concentration is 4000mg / m³. 3 The waste gas is introduced into the first absorption tower, which has a diameter of 30 mm and a specific surface area of ​​200 m². 2 / m 3A packed tower with built-in ceramic Pall rings and a porosity of 80% is used. The operating temperature is 35℃. The tower contains a total of 80L of special sodium hydroxide absorbent, in which the mass fraction of sodium hydroxide is 20% and the mass fraction of sodium acetate is 20%.

[0058] In the first absorption tower, a first gas and an alkaline solution containing sodium acetate are obtained. The alkaline solution containing sodium acetate is sent to the first circulation tank to form the first circulation liquid. The sodium acetate in the first circulation tank is discharged for recycling, and the remaining alkaline solution is sent back to the first absorption tower for recycling.

[0059] The first gas discharged from the first absorption tower is connected to the second absorption tower, which has a diameter of 30 mm and a specific surface area of ​​200 m². 2 / m 3 A packed tower with built-in ceramic Pall rings and a porosity of 80% was used, with an operating temperature of 35℃. The second absorption tower contained 80L of ethylene glycol absorbent with a 30% ethylene glycol mass fraction. After absorbing the first gas with the ethylene glycol absorbent for 60 minutes, purified gas and an ethylene glycol-ethanol mixture were obtained.

[0060] The ethylene glycol-ethanol mixture is fed into the second circulation tank to form the second circulation absorbent, which is then fed into the second absorption tower for recycling.

[0061] After the second absorption tower has been running for 15 hours, the ethylene glycol-ethanol mixture is pumped into the stripping tower, i.e., the distillation tower, for distillation (the bottom temperature is controlled at 120°C and the top temperature at 82°C), yielding ethanol and ethylene glycol absorbent. The obtained ethanol is recovered and stored, while the obtained ethylene glycol absorbent is recycled back into the absorption tower for further processing.

[0062] The concentration of ethyl acetate was determined to be 3.7 mg / m³ by detecting VOCs in the purified gas at the air outlet. 3 The absorption efficiency is 99.91%.

[0063] Example 2

[0064] The process for absorbing ethyl acetate from waste gas using a special absorbent in this embodiment is basically the same as in Example 1, except that the concentration of ethyl acetate in the waste gas is 3500 mg / m³. 3 The ethylene glycol absorbent absorbs the first gas for 60 minutes to obtain an ethylene glycol-ethanol mixture. After the second absorber runs for 15 hours, the ethylene glycol-ethanol mixture is pumped into the stripping column, i.e., the distillation column, for distillation.

[0065] The concentration of ethyl acetate was determined to be 3.4 mg / m³ by detecting VOCs in the purified gas at the outlet. 3 The absorption efficiency is 99.90%.

[0066] Example 3

[0067] The process for absorbing ethyl acetate from waste gas using a special absorbent in this embodiment is basically the same as in Example 1, except that the concentration of ethyl acetate in the waste gas is 3000 mg / m³. 3 The ethylene glycol absorbent absorbs the first gas for 75 minutes to obtain an ethylene glycol-ethanol mixture. After the second absorber runs for 15 hours, the ethylene glycol-ethanol mixture is pumped into the stripping column, i.e., the distillation column, for distillation.

[0068] The concentration of ethyl acetate was determined to be 3.5 mg / m³ by detecting VOCs in the purified gas at the outlet. 3 The absorption efficiency is 99.88%.

[0069] Example 4

[0070] The process for absorbing ethyl acetate in waste gas using a special absorbent in this embodiment is basically the same as in Example 1, except that the concentration of ethyl acetate in the waste gas is 2000 mg / m³. 3 The ethylene glycol absorbent absorbs the first gas for 60 minutes to obtain an ethylene glycol-ethanol mixture. After the second absorber runs for 15 hours, the ethylene glycol-ethanol mixture is pumped into the stripping column, i.e., the distillation column, for distillation.

[0071] The concentration of ethyl acetate was determined to be 3.1 mg / m³ by detecting VOCs in the purified gas at the outlet. 3 The absorption efficiency is 99.85%.

[0072] Example 5

[0073] The process for absorbing ethyl acetate in waste gas using a special absorbent in this embodiment is basically the same as in Example 1, except that the concentration of ethyl acetate in the waste gas is 1500 mg / m³. 3 The ethylene glycol absorbent absorbs the first gas for 75 minutes to obtain an ethylene glycol-ethanol mixture. After the second absorber runs for 15 hours, the ethylene glycol-ethanol mixture is pumped into the stripping column, i.e., the distillation column, for distillation.

[0074] The concentration of ethyl acetate was determined to be 1.8 mg / m³ by detecting VOCs in the purified gas at the outlet. 3 The absorption efficiency is 99.88%.

[0075] Example 6

[0076] The process for absorbing ethyl acetate in waste gas using a special absorbent in this embodiment is basically the same as in Example 1, except that the concentration of ethyl acetate in the waste gas is 3250 mg / m³. 3The ethylene glycol absorbent absorbs the first gas for 90 minutes to obtain an ethylene glycol-ethanol mixture. After the second absorber runs for 15 hours, the ethylene glycol-ethanol mixture is pumped into the stripping column, i.e., the distillation column, for distillation.

[0077] The concentration of ethyl acetate was determined to be 3.0 mg / m³ by detecting VOCs in the purified gas at the outlet. 3 The absorption efficiency is 99.91%.

[0078] Example 7

[0079] The process for absorbing ethyl acetate in waste gas using a special absorbent in this embodiment is basically the same as in Example 1, except that the concentration of ethyl acetate in the waste gas is 2250 mg / m³. 3 The ethylene glycol absorbent absorbs the first gas for 90 minutes to obtain an ethylene glycol-ethanol mixture. After the second absorber runs for 15 hours, the ethylene glycol-ethanol mixture is pumped into the stripping column, i.e., the distillation column, for distillation.

[0080] The concentration of ethyl acetate was determined to be 2.6 mg / m³ by detecting VOCs in the purified gas at the outlet. 3 The absorption efficiency is 99.88%.

[0081] Example 8

[0082] In this embodiment, the process for absorbing ethyl acetate from waste gas using a special absorbent is basically the same as in Example 3. The difference is that a third catalyst bed is provided above the ceramic Pall rings in both the first and second absorption towers. The height of the third catalyst bed is 0.3 times the total height of the absorption tower body, and the third catalyst bed is the composite catalyst used in Preparation Example 4. The first gas in the first absorption tower passes through the third catalyst bed and then enters the second absorption tower. In the second absorption tower, after passing through the third catalyst bed, it is absorbed by the ethylene glycol absorbent.

[0083] The concentration of ethyl acetate was determined to be 2.7 mg / m³ by detecting VOCs in the purified gas at the outlet. 3 The absorption efficiency is 99.91%.

[0084] Example 9

[0085] In this embodiment, the process for absorbing ethyl acetate from waste gas using a special absorbent is basically the same as in Example 3. The difference lies in that a second catalyst bed and a third catalyst bed are arranged from bottom to top above the ceramic Pall rings in both the first and second absorption towers. The second and third catalyst beds are at the same height, and their total height is 0.3 times the total height of the absorption tower body. The second catalyst bed is the composite catalyst of Preparation Example 3, and the third catalyst bed is the composite catalyst of Preparation Example 4. The first gas in the first absorption tower passes through the second and third catalyst beds and then enters the second absorption tower. In the second absorption tower, after passing through the second and third catalyst beds, it is absorbed by the ethylene glycol absorbent.

[0086] The concentration of ethyl acetate was determined to be 2.1 mg / m³ by detecting VOCs in the purified gas at the outlet. 3 The absorption efficiency is 99.93%.

[0087] Example 10

[0088] In this embodiment, the process for absorbing ethyl acetate from waste gas using a special absorbent is basically the same as in Example 3. The difference is that in both the first and second absorption towers, a first catalyst bed, a second catalyst bed, and a third catalyst bed are arranged from bottom to top above the ceramic Pall rings. The first, second, and third catalyst beds are arranged at the same height, and their total height is 0.3 times the total height of the absorption tower body. The first catalyst bed is the composite catalyst of Preparation Example 1, the second catalyst bed is the composite catalyst of Preparation Example 3, and the third catalyst bed is the composite catalyst of Preparation Example 4.

[0089] The concentration of ethyl acetate was determined to be 1.2 mg / m³ by detecting VOCs in the purified gas at the outlet. 3 The absorption efficiency is 99.96%.

[0090] In this embodiment, after the process continued for 60 hours, the VOCs of the purified gas at the outlet were detected, and the ethyl acetate concentration was determined to be 2.5 mg / m³. 3 The absorption efficiency is 99.92%.

[0091] Example 11

[0092] In this embodiment, the process for absorbing ethyl acetate from waste gas using a special absorbent is basically the same as in Example 3. The difference is that in both the first and second absorption towers, a first catalyst bed, a second catalyst bed, and a third catalyst bed are arranged from bottom to top above the ceramic Pall rings. The first, second, and third catalyst beds are arranged at the same height, and their total height is 0.3 times the total height of the absorption tower body. The first catalyst bed is the composite catalyst of Preparation Example 2, the second catalyst bed is the composite catalyst of Preparation Example 3, and the third catalyst bed is the composite catalyst of Preparation Example 4.

[0093] The concentration of ethyl acetate was determined to be 1.2 mg / m³ by detecting VOCs in the purified gas at the outlet. 3 The absorption efficiency is 99.97%.

[0094] In this embodiment, after the process was carried out for 60 hours, the VOCs of the purified gas at the outlet were detected, and the ethyl acetate concentration was determined to be 1.6 mg / m³. 3 The absorption efficiency is 99.95%.

[0095] In summary, this invention utilizes a series of ethyl acetate and ethanol absorption towers, with special sodium hydroxide and ethylene glycol as absorbents, respectively. The process first converts ethyl acetate into more easily recoverable ethanol through a chemical reaction, and then performs analysis and recovery. This not only overcomes the problems of low absorption capacity and low absorption efficiency of absorbents in the traditional absorption of ethyl acetate, achieving ultra-low VOC emissions, but also produces industrial resources such as sodium acetate and ethanol at low cost, fully realizing the recycling of resources.

[0096] 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 the spirit or essential characteristics of this disclosure. 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, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this disclosure.

[0097] 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 process for absorbing ethyl acetate from waste gas using a special absorbent, characterized in that, Includes the following steps: The waste gas containing ethyl acetate is passed into the first absorption tower containing a special sodium hydroxide absorbent to obtain a first gas containing ethanol and an alkaline solution containing sodium acetate. An alkaline solution containing sodium acetate is fed into a first circulation tank to form a first circulation absorbent; the sodium acetate in the first circulation tank is recovered, and the special sodium hydroxide absorbent in the first circulation tank is returned to the first absorption tower. The first gas is passed into a second absorption tower containing an aqueous solution of ethylene glycol to obtain purified gas and a mixture containing ethanol and ethylene glycol. A mixture containing ethanol and ethylene glycol is fed into a stripping column to strip out ethanol and ethylene glycol solutions. The ethanol is recovered and the ethylene glycol solution is returned to the second absorption column.

2. The process for absorbing ethyl acetate from waste gas using a special absorbent according to claim 1, characterized in that, In the first absorption tower, the volume of the special sodium hydroxide absorbent is 80L~100L, and the flow rate of the waste gas is 250L / h~300L / h.

3. The process for absorbing ethyl acetate from waste gas using a special absorbent according to claim 1, characterized in that, In the second absorption tower, the volume of ethylene glycol absorption liquid is 80L~100L, and the flow rate of the first gas is 250L / h~300L / h.

4. The process for absorbing ethyl acetate from waste gas using a special absorbent according to claim 1, characterized in that, In the first absorption tower, the special sodium hydroxide absorbent is a mixed solution of sodium hydroxide and sodium acetate, wherein the mass fraction of sodium hydroxide is 10%-30% and the mass fraction of sodium acetate is 10%-30%; and / or, In the second absorption tower, the mass fraction of ethylene glycol in the ethylene glycol absorption liquid is 20%-50%.

5. The process for absorbing ethyl acetate from waste gas using a special absorbent according to claim 1, characterized in that, The mixture containing ethanol and ethylene glycol is fed into the second circulation tank to form the second circulation liquid, and the second circulation liquid is returned to the second absorption tower. When the second absorption tower has been running for 15-20 hours, the mixture containing ethanol and ethylene glycol is fed into the desorption tower for desorption.

6. The process for absorbing ethyl acetate from waste gas using a special absorbent according to claim 1, characterized in that, Both the first and second absorption towers are provided with a first catalyst bed, a second catalyst bed, and a third catalyst bed from bottom to top. The first catalyst bed is a composite catalyst of activated carbon powder and glass fiber, wherein polyacrylamide is supported on the activated carbon powder; The second catalyst bed is a composite catalyst of activated carbon powder and glass fiber. The activated carbon powder is loaded with silane and polyacrylamide. The silane is at least one of methyltrimethoxysilane, isobutyltriethoxysilane, and hexyltrimethoxysilane. The weight ratio of the silane to the polyacrylamide is 1:(0.8-2). The third catalyst bed is a composite catalyst of activated carbon powder and glass fiber, wherein the activated carbon powder is loaded with octadecyltrimethoxysilane.

7. The process for absorbing ethyl acetate from waste gas using a special absorbent according to claim 6, characterized in that, Assuming the mass of polyacrylamide is 5%-10% of the mass of activated carbon powder, the activated carbon powder is soaked in a polyacrylamide aqueous solution for a certain period of time, then removed and dried at 60℃-70℃ for 1-2 hours to obtain activated carbon powder loaded with polyacrylamide.

8. The process for absorbing ethyl acetate from waste gas using a special absorbent according to claim 7, characterized in that, With a mass ratio of activated carbon powder to mesoporous silica of 1:(0.1-0.3), activated carbon powder loaded with polyacrylamide and mesoporous silica are mixed and then adsorbed under vacuum conditions to obtain activated carbon powder loaded with polyacrylamide and mesoporous silica.

9. The process for absorbing ethyl acetate from waste gas using a special absorbent according to claim 6, characterized in that, The silane and polyacrylamide were dispersed in an aqueous ethanol solution, and activated carbon powder was added for soaking. After soaking, the carbon powder was dried to obtain activated carbon powder loaded with silane and polyacrylamide.

10. The process for absorbing ethyl acetate from waste gas using a special absorbent according to claim 6, characterized in that, The octadecyltrimethoxysilane was dispersed in an aqueous ethanol solution, and activated carbon powder was added and soaked. After being removed and dried, activated carbon powder loaded with octadecyltrimethoxysilane was obtained.

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