A method for recovering volatile organic compounds from waste gas

Abstract

This application relates to the field of separation technology, specifically disclosing a method for recovering volatile organic compounds (VOCs) from waste gas. The method includes the following steps: S1, passing the waste gas and an absorption solvent into an absorption tower for absorption, and collecting the rich liquid; S2, passing the rich liquid into a desorption tower for indirect heating and desorption, collecting organic vapors, condensing, collecting the condensate, and obtaining the recovered organic matter; the absorption solvent is made from the following raw materials in weight percentages: 25-35% tributylmethylphosphine iodide, 15-25% isopropyltriphenylphosphine iodide, 3-7% (fluoromethyl)tetrafluoroborate triphenylphosphine, 3-7% (1-butyl-3-methylimidazolium chloride), and 35-50% alcohol-containing compounds and / or carboxylic acid-containing compounds. This method achieves an absorption rate >95%, improving the recovery of VOCs from waste gas and meeting market demand.

Description

Technical Field

[0001] This application relates to the field of separation technology, and more specifically, to a method for recovering volatile organic compounds from waste gas. Background Technology

[0002] Volatile organic compounds (VOCs) are a class of organic compounds with high vapor pressure and strong volatility, widely generated in industrial processes such as petrochemical plant operation and tank storage. They mainly include aromatics, halogenated hydrocarbons, alcohols, aldehydes, esters, alkenes, and alkanes. VOCs not only pollute the atmospheric environment and participate in the formation of photochemical smog and fine particulate matter, but some substances also pose carcinogenic, teratogenic, and mutagenic risks, seriously endangering human health. Therefore, the efficient recovery of VOCs from petrochemical waste gases has significant environmental and economic value. Traditional VOC recovery from waste gases generally involves absorption, desorption, and condensation to obtain the recovered organic matter. The absorbents used in the absorption process are mainly activated carbon, zeolite, molecular sieves, and activated alumina. However, these absorbents are prone to clogging during use, affecting the absorption rate. Summary of the Invention

[0003] To improve the absorption rate and thus enhance the recovery of volatile organic compounds (VOCs) from waste gas, this application provides a method for recovering VOCs from waste gas, employing the following technical solution:

[0004] S1. At a temperature of 20-40℃, the waste gas and absorption solvent are passed into the absorption tower for absorption. The volatile organic compounds in the waste gas are absorbed by the absorption solvent to form purified gas and rich liquid. The rich liquid is collected.

[0005] S2. At a temperature of 80-120℃ and a pressure of 5-30kPa, the rich liquid collected in step S1 is passed into the desorption tower for indirect heating and desorption. Volatile organic compounds in the rich liquid are released to form organic vapor and lean liquid. The organic vapor is collected, condensed, and non-condensable gas and condensate are formed. The condensate is collected to obtain recovered organic matter.

[0006] The absorbent solvent is made from the following raw materials in weight percentages: 25-35% tributylmethylphosphine iodide, 15-25% isopropyltriphenylphosphine iodide, 3-7% (fluoromethyl)tetrafluoroborate triphenylphosphine, 3-7% (1-butyl-3-methylimidazolium chloride), and 35-50% alcohol-containing compounds and / or carboxylic acid-containing compounds.

[0007] The method for recovering volatile organic compounds (VOCs) from waste gas disclosed in this application involves absorbing organic solvents from the waste gas using an absorption solvent in an absorption tower, followed by desorption in a desorption tower, and finally condensation to obtain the recovered organic compounds, thus achieving the recovery of VOCs. This method, through the synergistic effect between the absorption solvent raw materials, achieves an absorption rate >95%, demonstrating high absorption efficiency and thereby improving the recovery of VOCs from waste gas, meeting market demands.

[0008] The absorbent solvent of this application simultaneously incorporates tributylmethylphosphine iodide, isopropyltriphenylphosphine iodide, (fluoromethyl)tetrafluoroborate triphenylphosphine, and chlorinated (1-butyl-3-methylimidazole). Tributylmethylphosphine iodide provides strong polarity and ionic interactions, isopropyltriphenylphosphine iodide provides π-π stacking interactions, (fluoromethyl)tetrafluoroborate triphenylphosphine provides fluoride-repellent interactions, and chlorinated (1-butyl-3-methylimidazole) provides multiple hydrogen bond sites. These four compounds complement each other and produce a synergistic effect, achieving efficient absorption of various types of volatile organic compounds and improving the absorption rate. Furthermore, alcohol-containing compounds and / or carboxylic acid-containing compounds are added. Alcohol-containing compounds increase the adsorption capacity for water-soluble volatile organic compounds, while carboxylic acid-containing compounds increase the absorption capacity for acidic volatile organic compounds. The selective use of alcohol-containing and carboxylic acid-containing compounds enhances the absorption effect of the absorbent solvent.

[0009] Optionally, the alcohol-containing compound is one or more of ethylene glycol, glycerol, propylene glycol, and butylene glycol; the carboxylic acid-containing compound is one or more of acetylpropionic acid, capric acid, butyric acid, and lactic acid.

[0010] By adopting the above technical solutions, the alcohol-containing compounds and carboxylic acid-containing compounds are optimized, which facilitates the selection of alcohol-containing compounds and carboxylic acid-containing compounds.

[0011] Optionally, the exhaust gas may originate from petrochemical plants and / or irrigation areas.

[0012] Optionally, the volatile organic compounds are one or more combinations of aromatic organic compounds, halogenated hydrocarbon organic compounds, alcohol organic compounds, aldehyde organic compounds, ester organic compounds, alkene organic compounds, and alkane organic compounds.

[0013] By adopting the above technical solution, the absorption solvent can efficiently absorb aromatic organic compounds, halogenated organic compounds, alcohol organic compounds, aldehyde organic compounds, ester organic compounds, alkene organic compounds, and alkane organic compounds, and has good broad-spectrum applicability, which is suitable for the needs of industrial waste gas treatment.

[0014] Optionally, the absorbent solvent is prepared by the following method: at a temperature of 60-70°C, tributylmethylphosphine iodide, isopropyltriphenylphosphine iodide, (fluoromethyl)tetrafluoroborate triphenylphosphine, (1-butyl-3-methylimidazolium chloride), an alcohol-containing compound and / or a carboxylic acid-containing compound are mixed and cooled to obtain the absorbent solvent.

[0015] By adopting the above technical solution, the preparation of the absorbent solvent is facilitated.

[0016] Optionally, in step S1, the ratio of absorption solvent to waste gas is (1-8) L / Nm³. 3 Preferably, the ratio of absorbent solvent to waste gas is (3-5) L / Nm³. 3 .

[0017] By adopting the above technical solution, the ratio of absorption solvent to waste gas is optimized to ensure the full absorption of volatile organic compounds in the waste gas. In several embodiments, in step S1, the ratio of absorption solvent to waste gas is 4 L / Nm³. 3 It can also be configured to set the absorption solvent to waste gas ratio of 1 L / Nm³ as needed. 3 2L / Nm 3 3L / Nm 3 5L / Nm 3 6L / Nm 3 7L / Nm 3 8L / Nm 3 This applies to, but is not limited to, the listed values; other unlisted values ​​within this range also apply.

[0018] Optionally, in step S1, the waste gas enters from the bottom of the absorption tower, the absorption solvent enters from the top of the absorption tower and is sprayed down, the purified gas is discharged from the top of the absorption tower, and the rich liquid is discharged from the bottom of the absorption tower.

[0019] By adopting the above technical solution, the waste gas and the absorption solvent are in countercurrent contact inside the absorption tower, ensuring full contact between the two and increasing mass transfer efficiency.

[0020] Optionally, in step S2, the rich liquor enters from the top of the stripping column and is sprayed down, the organic vapor is discharged from the top of the stripping column, and the lean liquor is discharged from the bottom of the stripping column.

[0021] By adopting the above technical solution, the rich liquid is sprayed down from the top of the analytical tower, which facilitates the precipitation of volatile organic compounds.

[0022] Optionally, the absorption tower is filled with inert packing material, the diameter of the absorption tower is 0.5-1.5m, and the height of the inert packing material inside the absorption tower is 2-5m; the desorption tower is filled with inert packing material, the diameter of the desorption tower is 1-3m, and the height of the inert packing material inside the desorption tower is 2-5m.

[0023] By adopting the above technical solution, the absorption tower is filled with inert packing material, which effectively improves the absorption rate. Similarly, the desorption tower is filled with inert packing material, which effectively improves the desorption rate. Furthermore, the tower diameter and the height of the inert packing material in both the absorption and desorption towers are optimized to facilitate absorption-desorption operation.

[0024] In several implementation schemes, the diameter of the absorption tower is 0.8m and the height of the inert packing inside the absorption tower is 3.5m. The tower diameter can also be set to 0.5m, 1m, 1.3m, 1.5m, etc., as needed, and the height can also be set to 2m, 2.5m, 3m, 4m, 4.5m, 5m, etc., as needed, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] In several implementation schemes, the diameter of the analytical column is 1.2m and the height of the inert packing inside the analytical column is 3.5m. The column diameter can also be set to 1m, 1.5m, 2m, 2.5m, 3m, etc., as needed, and the height can also be set to 2m, 2.5m, 3m, 4m, 4.5m, 5m, etc., as needed, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] Optionally, the inert filler has dimensions of (10-80) mm × (10-80) mm × (1-9) mm and an average specific surface area of ​​60-200 m². 2 / m 3 The porosity is 60-80%.

[0027] By adopting the above technical solution, the size, average specific surface area, and porosity of the inert packing are optimized, facilitating the selection of inert packing materials. Furthermore, it provides a sufficient contact interface for the absorption solvent and waste gas, enhancing mass transfer efficiency, reducing waste gas flow resistance, and thus improving the absorption rate.

[0028] Optionally, the inert filler is one or more of Pall rings, step rings, and rosettes.

[0029] Optionally, the inert filler material is one or a combination of ceramic, plastic, and stainless steel.

[0030] In summary, this application has at least the following beneficial effects:

[0031] 1. The method for recovering volatile organic compounds (VOCs) from waste gas disclosed in this application achieves the recovery of VOCs from waste gas through the coordinated action of absorption, desorption, and condensation. Furthermore, through the coordinated action of the absorption solvent raw materials, the absorption rate is >95%, exhibiting a high absorption rate, thereby improving the recovery of VOCs from waste gas and meeting market demands.

[0032] 2. The absorption solvent of this application, through tributylmethylphosphine iodide, isopropyltriphenylphosphine iodide, (fluoromethyl)tetrafluoroborate triphenylphosphine, and chlorinated (1-butyl-3-methylimidazolium), forms a functional complement and produces a synergistic effect, thereby achieving efficient absorption of various types of volatile organic compounds, improving the absorption rate, and enhancing the absorption effect. Detailed Implementation

[0033] The present application will be further described in detail below with reference to the embodiments.

[0034] Preparation Example

[0035] Table 1. Amount of raw materials used for absorbing solvent (unit: kg)

[0036]

[0037] Preparation Example 1

[0038] An absorbent solvent, the raw materials and their proportions are shown in Table 1.

[0039] Among them, the alcohol-containing compound is ethylene glycol.

[0040] A method for preparing an absorbent solvent includes the following steps:

[0041] At a temperature of 65°C, isopropyltriphenylphosphine iodide, (fluoromethyl)tetrafluoroborate triphenylphosphine, and chlorinated (1-butyl-3-methylimidazolium) were added to tributylmethylphosphine iodide and stirred for 1 hour. Then, an alcohol-containing compound was added and stirred for 4 hours. The temperature was then lowered to 40°C to obtain the absorbent solvent.

[0042] Preparation Example 2

[0043] An absorbent solvent differs from Preparation Example 1 in that the raw material ratio of the absorbent solvent is different, and the raw material ratio of the absorbent solvent is shown in Table 1.

[0044] Preparation Example 3

[0045] An absorbent solvent differs from Preparation Example 1 in that the raw material ratio of the absorbent solvent is different, and the raw material ratio of the absorbent solvent is shown in Table 1.

[0046] Preparation Example 4

[0047] An absorbent solvent, the raw materials and their proportions are shown in Table 1.

[0048] Among them, the carboxylic acid compound is levulinic acid.

[0049] A method for preparing an absorbent solvent includes the following steps:

[0050] At a temperature of 65°C, isopropyltriphenylphosphine iodide, (fluoromethyl)tetrafluoroborate triphenylphosphine, and chlorinated (1-butyl-3-methylimidazolium) were added to tributylmethylphosphine iodide and stirred for 1 hour. Then, a carboxylic acid compound was added and stirred for 4 hours. The mixture was then cooled to 40°C to obtain the absorbent solvent.

[0051] Preparation Example 5

[0052] An absorbent solvent differs from Preparation Example 4 in that the raw material ratio of the absorbent solvent is different, and the raw material ratio of the absorbent solvent is shown in Table 1.

[0053] Preparation Example 6

[0054] An absorbent solvent differs from Preparation Example 4 in that the raw material ratio of the absorbent solvent is different, and the raw material ratio of the absorbent solvent is shown in Table 1.

[0055] Preparation Example 7

[0056] An absorbent solvent differs from Preparation Example 4 in that the source of the carboxylic acid compound in the raw materials of the absorbent solvent is different, and the carboxylic acid compound is capric acid. The raw material ratio of the absorbent solvent is shown in Table 1.

[0057] Example

[0058] Example 1

[0059] A method for recovering volatile organic compounds from waste gas includes the following steps:

[0060] S1. An absorption tower is used. At a temperature of 40℃, the waste gas is introduced into the absorption tower from the bottom, while the absorbent solvent is introduced into the absorption tower from the top and sprayed downwards. The waste gas and the absorbent solvent come into contact inside the absorption tower, and the volatile organic compounds in the waste gas are absorbed by the absorbent solvent, forming purified gas and rich liquid. The purified gas is discharged from the top of the absorption tower, and the rich liquid is discharged from the bottom of the absorption tower and collected.

[0061] The waste gas consists of volatile organic compounds (VOCs) and air. The VOCs are aromatic hydrocarbons, specifically toluene and benzene. The VOC content is 2000 ppm, the benzene content is 1000 ppm, and the remainder is air. The absorbent solvent was prepared using the method described in Preparation Example 1.

[0062] The absorption tower is filled with inert packing material, which consists of ceramic Pall rings. The ceramic Pall rings have dimensions of 50mm × 50mm × 2mm and an average specific surface area of ​​120m². 2 / m 3 The porosity is 73%. The absorption tower has a diameter of 0.8m and a height of 3.5m for the inert packing material. The waste gas treatment capacity is 1000 Nm³. 3 / h. The ratio of absorbent solvent to waste gas is 4L / Nm³. 3 .

[0063] S2. Using a stripping column, at a temperature of 100℃ and a pressure of 18kPa, the rich liquid collected in step S1 is passed from the top of the column and sprayed downwards. Through indirect heating and stripping, volatile organic compounds in the rich liquid are released, forming organic vapor and lean liquid. The organic vapor is discharged from the top of the stripping column, and the lean liquid is discharged from the bottom. The organic vapor is collected. A condenser is used to condense the organic vapor, forming non-condensable gas and condensate. The condensate is collected to obtain recovered organic matter.

[0064] The analytical column is filled with inert packing material, specifically ceramic Pall rings, with dimensions of 50mm × 50mm × 2mm and an average specific surface area of ​​120m². 2 / m 3 The porosity is 73%. The diameter of the analytical column is 1.2m, and the height of the inert packing inside the analytical column is 3.5m.

[0065] Example 2

[0066] A method for recovering volatile organic compounds from waste gas differs from Example 1 in that the source of the absorbent solvent in step S1 is different, and the absorbent solvent is prepared by the preparation method of Example 2.

[0067] Example 3

[0068] A method for recovering volatile organic compounds from waste gas differs from Example 1 in that the source of the absorbent solvent in step S1 is different, and the absorbent solvent is prepared using the preparation method of Preparation Example 3.

[0069] Example 4

[0070] A method for recovering volatile organic compounds from waste gas differs from Example 1 in that the source of the waste gas is different in step S1, and the temperature and pressure of the desorption process are different in step S2.

[0071] In step S1, the exhaust gas consists of volatile organic compounds and air. The volatile organic compounds are halogenated hydrocarbons, specifically chloromethane and dichloromethane. The exhaust gas contains 2000 ppm of chloromethane and 1000 ppm of dichloromethane, with the remainder being air.

[0072] In step S2, the temperature for analysis is 100℃ and the pressure is 8kPa.

[0073] Example 5

[0074] A method for recovering volatile organic compounds from waste gas differs from Example 1 in that the sources of the waste gas and absorption solvent are different in step S1, and the temperature and pressure of the desorption process are different in step S2.

[0075] In step S1, the waste gas consists of volatile organic compounds (VOCs) and air. The VOCs are alcohols, specifically methanol and butanol. The waste gas contains 1500 ppm of methanol and 1500 ppm of butanol, with the remainder being air. The absorbent solvent was prepared using the method described in Preparation Example 4.

[0076] In step S2, the temperature for analysis is 110℃ and the pressure is 18kPa.

[0077] Example 6

[0078] A method for recovering volatile organic compounds from waste gas differs from Example 1 in that the sources of the waste gas and absorption solvent are different in step S1, and the temperature and pressure of the desorption process are different in step S2.

[0079] In step S1, the exhaust gas consists of volatile organic compounds (VOCs) and air. The VOCs are aldehydes, specifically acetaldehyde and propionaldehyde. The exhaust gas contains 1000 ppm of acetaldehyde and 1000 ppm of propionaldehyde, with the remainder being air. The absorbent solvent was prepared using the method described in Preparation Example 5.

[0080] In step S2, the temperature for analysis is 85℃ and the pressure is 6kPa.

[0081] Example 7

[0082] A method for recovering volatile organic compounds from waste gas differs from Example 1 in that the sources of the waste gas and absorption solvent are different in step S1, and the temperature and pressure of the desorption process are different in step S2.

[0083] In step S1, the waste gas consists of volatile organic compounds and air. The volatile organic compounds are ester organic compounds, specifically ethyl acetate and propyl acetate. The waste gas contains 1500 ppm of ethyl acetate and 1500 ppm of propyl acetate, with the remainder being air. The absorption solvent was prepared using the method described in Preparation Example 6.

[0084] In step S2, the temperature for analysis is 95℃ and the pressure is 12kPa.

[0085] Example 8

[0086] A method for recovering volatile organic compounds from waste gas differs from Example 1 in that the sources of the waste gas and absorption solvent are different in step S1, and the temperature and pressure of the desorption process are different in step S2.

[0087] In step S1, the waste gas consists of volatile organic compounds (VOCs) and air. The VOCs are olefinic organic compounds, specifically propylene and butene. The waste gas contains 2500 ppm of propylene and 500 ppm of butene, with the remainder being air. The absorbent solvent was prepared using the method described in Preparation Example 7.

[0088] In step S2, the temperature for analysis is 90℃ and the pressure is 10kPa.

[0089] Example 9

[0090] A method for recovering volatile organic compounds from waste gas differs from Example 1 in that the sources of the waste gas and absorption solvent are different in step S1, and the temperature and pressure of the desorption process are different in step S2.

[0091] In step S1, the exhaust gas consists of volatile organic compounds (VOCs) and air. The VOCs are alkane-based organic compounds, specifically propane and n-hexane. The exhaust gas contains 2000 ppm of propane and 1000 ppm of n-hexane, with the remainder being air. The absorbent solvent was prepared using the method described in Preparation Example 7.

[0092] In step S2, the temperature for analysis is 90℃ and the pressure is 12kPa.

[0093] Comparative Example

[0094] Comparative Example 1

[0095] A method for recovering volatile organic compounds from waste gas, which differs from Example 1 in that, in step S1, in the raw materials of the absorbent solvent, isopropyltriphenylphosphine iodide, (fluoromethyl)tetrafluoroborate triphenylphosphine, and chlorinated (1-butyl-3-methylimidazole) are replaced with an equal amount of tributylmethylphosphine iodide.

[0096] Comparative Example 2

[0097] A method for recovering volatile organic compounds from waste gas, which differs from Example 1 in that, in step S1, an equal amount of isopropyltriphenylphosphine iodide is used to replace (fluoromethyl)tetrafluoroborate triphenylphosphine and chlorinated (1-butyl-3-methylimidazole) in the raw materials for absorbing solvent.

[0098] Comparative Example 3

[0099] A method for recovering volatile organic compounds from waste gas, which differs from Example 1 in that, in step S1, an equal amount of (fluoromethyl)tetrafluoroborate triphenylphosphine is used to replace chlorinated (1-butyl-3-methylimidazole) in the raw material for absorbing the solvent.

[0100] Comparative Example 4

[0101] A method for recovering volatile organic compounds from waste gas, which differs from Example 1 in that, in step S1, an equal amount of (fluoromethyl)tetrafluoroborate triphenylphosphine is replaced with (1-butyl-3-methylimidazolium chloride) in the raw material of the absorbent solvent.

[0102] Performance testing

[0103] The purified gases obtained in step S1 of Examples 1-9 and Comparative Examples 1-4 were taken respectively, and the content of volatile organic compounds in the purified gases was detected, and the absorption rate was calculated.

[0104] Absorption rate (%) = (VOC content in exhaust gas - VOC content in purified gas) / VOC content in exhaust gas × 100%.

[0105] Table 2 Test Results

[0106]

[0107] As can be seen from Table 2, in the method for recovering volatile organic compounds from waste gas proposed in this application, the absorption solvent has a high absorption rate of 95.2-99.3% for volatile organic compounds in waste gas, with an absorption rate of >95%. It can achieve efficient absorption of aromatic organic compounds, halogenated hydrocarbon organic compounds, alcohol organic compounds, aldehyde organic compounds, ester organic compounds, alkene organic compounds, and alkane organic compounds. It has the advantages of wide applicability and high absorption rate, which meets market demand.

[0108] Comparative Examples 1 and 2 were compared. In Comparative Example 1, tributylmethylphosphine iodide was added to the raw material of the absorbent solvent; in Comparative Example 2, both tributylmethylphosphine iodide and isopropyltriphenylphosphine iodide were added to the raw material of the absorbent solvent. This demonstrates that simultaneously adding tributylmethylphosphine iodide and isopropyltriphenylphosphine iodide to the raw material of the absorbent solvent significantly improves the absorption rate through their synergistic effect.

[0109] Comparative Examples 3-4 and Example 1 were compared. In Comparative Example 3, the raw materials for the absorbent solvent contained tributylmethylphosphine iodide, isopropyltriphenylphosphine iodide, and (fluoromethyl)tetrafluoroborate triphenylphosphine; in Comparative Example 4, the raw materials for the absorbent solvent contained tributylmethylphosphine iodide, isopropyltriphenylphosphine iodide, and (1-butyl-3-methylimidazole) chloride; and in Example 1, the raw materials for the absorbent solvent contained tributylmethylphosphine iodide, isopropyltriphenylphosphine iodide, (fluoromethyl)tetrafluoroborate triphenylphosphine, and (1-butyl-3-methylimidazole) chloride. This demonstrates that by adding tributylmethylphosphine iodide and isopropyltriphenylphosphine iodide to the absorption solvent, further addition of (fluoromethyl)tetrafluoroborate triphenylphosphine and (1-butyl-3-methylimidazole) chloride provides strong polarity and ionic interaction, isopropyltriphenylphosphine iodide provides π-π stacking interaction, (fluoromethyl)tetrafluoroborate triphenylphosphine provides fluoride-repellent interaction, and (1-butyl-3-methylimidazole) chloride provides multiple hydrogen bond sites. The four components complement each other and produce a synergistic effect, further improving the absorption rate and enhancing the absorption effect of the absorption solvent.

[0110] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for recovering volatile organic compounds from waste gas, characterized in that: Includes the following steps: S1. At a temperature of 20-40℃, the waste gas and absorption solvent are passed into the absorption tower for absorption. The volatile organic compounds in the waste gas are absorbed by the absorption solvent to form purified gas and rich liquid. The rich liquid is collected. S2. At a temperature of 80-120℃ and a pressure of 5-30kPa, the rich liquid collected in step S1 is passed into the desorption tower for indirect heating and desorption. Volatile organic compounds in the rich liquid are released to form organic vapor and lean liquid. The organic vapor is collected, condensed, and non-condensable gas and condensate are formed. The condensate is collected to obtain recovered organic matter. The absorbent solvent is made from the following raw materials in weight percentages: 25-35% tributylmethylphosphine iodide, 15-25% isopropyltriphenylphosphine iodide, 3-7% (fluoromethyl)tetrafluoroborate triphenylphosphine, 3-7% (1-butyl-3-methylimidazolium chloride), and 35-50% alcohol-containing compounds and / or carboxylic acid-containing compounds.

2. The method for recovering volatile organic compounds from waste gas according to claim 1, characterized in that: The alcohol-containing compound is one or more of ethylene glycol, glycerol, propylene glycol, and butylene glycol; the carboxylic acid-containing compound is one or more of acetylpropionic acid, capric acid, butyric acid, and lactic acid.

3. The method for recovering volatile organic compounds from waste gas according to claim 1, characterized in that: The exhaust gas originates from petrochemical plants and / or irrigation areas.

4. The method for recovering volatile organic compounds from waste gas according to claim 1, characterized in that: The volatile organic compounds are one or more of the following: aromatic organic compounds, halogenated hydrocarbon organic compounds, alcohol organic compounds, aldehyde organic compounds, ester organic compounds, alkene organic compounds, and alkane organic compounds.

5. The method for recovering volatile organic compounds from waste gas according to claim 1, characterized in that: The absorbent solvent is prepared by the following method: at a temperature of 60-70℃, tributylmethylphosphine iodide, isopropyltriphenylphosphine iodide, (fluoromethyl)tetrafluoroborate triphenylphosphine, (1-butyl-3-methylimidazolium chloride), an alcohol-containing compound and / or a carboxylic acid-containing compound are mixed and cooled to obtain the absorbent solvent.

6. The method for recovering volatile organic compounds from waste gas according to claim 1, characterized in that: In step S1, the ratio of absorption solvent to waste gas is (1-8) L / Nm³. 3 .

7. The method for recovering volatile organic compounds from waste gas according to claim 1, characterized in that: In step S1, the waste gas enters from the bottom of the absorption tower, the absorption solvent enters from the top of the absorption tower and is sprayed down, the purified gas is discharged from the top of the absorption tower, and the rich liquid is discharged from the bottom of the absorption tower.

8. The method for recovering volatile organic compounds from waste gas according to claim 1, characterized in that: In step S2, the rich liquor enters from the top of the stripping column and is sprayed down, the organic vapor is discharged from the top of the stripping column, and the lean liquor is discharged from the bottom of the stripping column.

9. The method for recovering volatile organic compounds from waste gas according to claim 1, characterized in that: The absorption tower is filled with inert packing material, the diameter of the absorption tower is 0.5-1.5m, and the height of the inert packing material inside the absorption tower is 2-5m; the desorption tower is filled with inert packing material, the diameter of the desorption tower is 1-3m, and the height of the inert packing material inside the desorption tower is 2-5m.

10. A method for recovering volatile organic compounds from waste gas according to claim 9, characterized in that: The inert filler has dimensions of (10-80) mm × (10-80) mm × (1-9) mm and an average specific surface area of ​​60-200 m². 2 / m 3 The porosity is 60-80%.

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