Hydrophobic VOCs absorbent, preparation method and application thereof, and method for removing benzene series VOCs

Abstract

The invention relates to the technical field of absorption treatment of benzene-series volatile organic compounds, and discloses a hydrophobic VOCs absorbent, a preparation method and application thereof, and a method for removing benzene-series VOCs. The saturated vapor pressure of the hydrophobic VOCs absorbent at 25 DEG C is less than 100 Pa, the saturated water content is less than 2%, and the freezing point is less than 10 DEG C; the absorbent contains a hydrogen bond donor B, a hydrogen bond acceptor and a composite component C; the hydrogen bond donor B is provided by fatty acid with a molecular formula of R '-COOH, and the hydrogen bond acceptor is provided by at least one of quaternary ammonium salt, menthol and thymol. According to the hydrophobic VOCs absorbent provided by the invention, the dynamic absorption effect of the absorbent is improved while efficient absorption of VOCs is ensured, and the absorbent is good in stability under a low-temperature condition by reducing the freezing point and can meet the application requirements of industrial scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of benzene-based volatile organic compound absorption treatment, and particularly relates to a hydrophobic VOCs absorbent, a preparation method and application thereof, and a method for removing benzene-based VOCs. Background Art

[0002] Benzene-based volatile organic compounds (VOCs) are the main components of industrial source VOCs and also the key components for treatment and control. Energy-saving and efficient recovery technologies have become the key development direction of current VOCs treatment technologies. Ionic liquids and deep eutectic solvents both have the advantages of extremely low saturated vapor pressure and low volatility, so as solvents and absorbents, they can effectively avoid the problems of secondary pollution and absorbent loss; in addition, the functions of ionic liquids and deep eutectic solvents can be designed, and it is easy to achieve efficient recovery of VOCs. In recent years, ionic liquids and deep eutectic solvents have gradually attracted the attention of domestic and foreign scholars in the field of VOCs absorption. However, problems such as complex synthesis, high price, and certain toxicity of ionic liquids limit their industrial applications. In comparison, deep eutectic solvents are more economical, green and environmentally friendly. Therefore, deep eutectic solvents have become promising conventional solvents and alternative solvents for ionic liquids.

[0003] At present, the related research on deep eutectic solvents in the field of volatile organic compounds (VOCs) absorption is still in its infancy. CN110114129A uses a deep eutectic solvent with a quaternary ammonium salt as a hydrogen bond acceptor to absorb VOCs, and adds cyclodextrin to improve the absorption capacity. CN110180329A uses a deep eutectic solvent composed of tetraethylammonium chloride and oleic acid to absorb benzene-based VOCs, and realizes a removal rate of more than 90% of benzene-based volatile substances through an absorption process combining an absorption tower and a flash tank. The above inventions have all verified that it is feasible to absorb VOCs with deep eutectic solvents. However, the quaternary ammonium salt-based deep eutectic solvents used in the above inventions usually have poor mass transfer effects, and the dynamic removal rate of VOCs needs to be improved, and they have a high freezing point and poor low-temperature stability, so it is difficult to meet the requirements of industrial scenario applications.

[0004] Therefore, there is an urgent need to provide a new type of benzene-based VOCs absorbent with good low-temperature stability and excellent mass transfer performance to meet the requirements of industrial scenario applications. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems of poor mass transfer performance and instability under low-temperature conditions existing in the existing benzene-based VOCs absorbents.

[0006] To achieve the above purpose, in the first aspect of the present invention, a hydrophobic VOCs absorbent is provided. The saturated vapor pressure of the absorbent at 25°C is less than 100 Pa, the saturated water content is less than 2 mol%, and the freezing point is less than 10°C; the absorbent contains a hydrogen bond donor B, a hydrogen bond acceptor, and a composite component C.

[0007] The composite component C is a combination of component D and component E; component D is selected from at least one of toluene and n-hexane; component E is selected from at least one of acetic acid, lactic acid, and pyruvic acid;

[0008] The hydrogen bond donor B is provided by a fatty acid with the molecular formula R'-COOH, where R' is C n H 2n+1 or C n H 2n-1 , and n is an integer from 5 to 17.

[0009] The hydrogen bond acceptor is provided by at least one of quaternary ammonium salts, menthol, and thymol, and the structure of the quaternary ammonium salt is Each R is the same and is selected from C 4-8 alkyl, and L is Cl or Br;

[0010] And the content relationship of each component in the absorbent satisfies formula (I) and formula (II):

[0011] H = A + yB + zC formula (I),

[0012] A = x1×A1 + x2×A2 + x3×A3 formula (II);

[0013] y, z, x1, x2, and x3 respectively satisfy the following conditions: 0.5 ≤ y / (x1 + x2 + x3) ≤ 5, 0 < z / (x1 + x2 + x3) ≤ 0.1, and x1, x2, and x3 are not all 0 at the same time;

[0014] H represents the total amount of components in the absorbent, A represents the total amount of hydrogen bond acceptors, y represents the amount of substance of hydrogen bond donor B, z represents the total amount of substance of composite component C, x1 represents the amount of substance of quaternary ammonium salt A1, x2 represents the amount of substance of menthol A2, x3 represents the amount of substance of thymol A3, and the amount of substance units of y, z, x1, x2, and x3 are the same.

[0015] The second aspect of the present invention provides a preparation method of a hydrophobic VOCs absorbent, and this method includes the following steps:

[0016] Perform a first mixing on the hydrogen bond acceptor, hydrogen bond donor B, and composite component C to obtain a hydrophobic VOCs absorbent;

[0017] The composite component C is a combination of component D and component E; component D is selected from at least one of toluene and n-hexane; component E is selected from at least one of acetic acid, lactic acid, and pyruvic acid;

[0018] The hydrogen bond donor B is provided by a fatty acid with the molecular formula R'-COOH, where R' is Cn H 2n+1 or C n H 2n-1 , where n is an integer from 5 to 17,

[0019] The hydrogen bond acceptor is provided by at least one of quaternary ammonium salts, menthol, and thymol. The structure of the quaternary ammonium salt is Each R is the same and is selected from C 4-8 alkyl group, and L is Cl or Br;

[0020] And the dosage relationship among the hydrogen bond acceptor, hydrogen bond donor B, and composite component C satisfies formula (I) and formula (II):

[0021] H = A + yB + zC Formula (I),

[0022] A = x1×A1 + x2×A2 + x3×A3 Formula (II);

[0023] Wherein, the definitions of H, A, y, z, x1, x2, x3, A1, A2, and A3 are the same as those defined in the first aspect.

[0024] The third aspect of the present invention provides a hydrophobic VOCs absorbent prepared by the method described in the second aspect.

[0025] The fourth aspect of the present invention provides the hydrophobic VOCs absorbent described in the first aspect and the third aspect for absorbing benzene-based VOCs.

[0026] The fifth aspect of the present invention provides a method for removing benzene-based VOCs from waste gas. The waste gas is contacted with the hydrophobic VOCs absorbent described in the first aspect and / or the third aspect to obtain a mixture containing benzene-based VOCs.

[0027] In the present invention, on the premise that the composite component, hydrogen bond donor, and hydrogen bond acceptor satisfy a specific content relationship, they are compounded to form a stable hydrophobic VOCs absorbent with a low saturated vapor pressure, avoiding secondary pollution and solvent loss caused by the volatilization of the absorbent, and being able to recover high-purity VOCs gas. While ensuring the efficient absorption of VOCs, it improves the mass transfer performance of the absorbent, enhances the dynamic absorption effect, and has good stability at low temperatures by lowering the freezing point, meeting the requirements of industrial scenario applications. Detailed Embodiments

[0028] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0029] As described above, the first aspect of the present invention provides a hydrophobic VOCs absorbent, the absorbent having a saturated vapor pressure of less than 100 Pa at 25 °C, a saturated water content of less than 2 mol%, and a freezing point of less than 10 °C; the absorbent contains a hydrogen bond donor B, a hydrogen bond acceptor, and a composite component C.

[0030] The composite component C is a combination of component D and component E; the component D is selected from at least one of toluene and n-hexane; the component E is selected from at least one of acetic acid, lactic acid, and pyruvic acid.

[0031] The hydrogen bond donor B is provided by a fatty acid with the molecular formula R'-COOH, where R' is C n H 2n+1 or C n H 2n-1 , n is an integer from 5 to 17.

[0032] The hydrogen bond acceptor is provided by at least one of quaternary ammonium salts, menthol, and thymol, and the structure of the quaternary ammonium salt is Each R is the same and is selected from alkyl groups of C 4-8 , and L is Cl or Br.

[0033] And the content relationship of each component in the absorbent satisfies formula (I) and formula (II):

[0034] H = A + yB + zC formula (I),

[0035] A = x1×A1 + x2×A2 + x3×A3 formula (II);

[0036] y, z, x1, x2, x3 respectively satisfy the following conditions: 0.5 ≤ y / (x1 + x2 + x3) ≤ 5, 0 < z / (x1 + x2 + x3) ≤ 0.1, and x1, x2, x3 are not all 0 at the same time.

[0037] H represents the total amount of components of the absorbent, A represents the total amount of hydrogen bond acceptors, y represents the amount of substance of the hydrogen bond donor B, z represents the total amount of substance of the composite component C, x1 represents the amount of substance of the quaternary ammonium salt A1, x2 represents the amount of substance of menthol A2, x3 represents the amount of substance of thymol A3, and the amount of substance units of y, z, x1, x2, x3 are the same.

[0038] In the present invention, "the units of the amounts of substances of y, z, x1, x2, and x3 are the same" means that the units of the amounts of substances of y, z, x1, x2, and x3 are the same. For example, the units of the amounts of substances of y, z, x1, x2, and x3 can be moles (mol), millimoles (mmol), etc.

[0039] In the present invention, the saturated vapor pressure of the hydrophobic VOCs absorbent is measured by thermogravimetric analysis, and the saturated water content is measured according to the Karl Fischer titration method. The saturated water content x w is calculated by the following formula: x w = n w / (n w + S) × 100%,

[0040] wherein, n w is the amount of substance of water, and S is the total molar amount of the absorbent components (i.e., the sum of the amounts of substances of each component).

[0041] Preferably, the hydrogen bond donor B is provided by a fatty acid. The molecular formula of the fatty acid is R'-COOH, wherein R' is C n H 2n+1 or C n H 2n-1 , and n is an integer from 7 to 17. More preferably, the hydrogen bond donor B is provided by at least one of n-octanoic acid, lauric acid, and oleic acid. The inventors have found that in this preferred case, the obtained hydrophobic VOCs absorbent has a better absorption effect on benzene-based VOCs.

[0042] Preferably, the hydrogen bond acceptor is provided by at least one substance selected from quaternary ammonium salts, menthol, and thymol. The quaternary ammonium salt is at least one of tetrabutylammonium chloride and tetrabutylammonium bromide. The inventors have found that the hydrogen bond acceptor in this preferred case, in combination with the specific types of hydrogen bond ligands and composite components of the present invention, can make the hydrophobic VOCs absorbent have a better absorption effect on benzene-based VOCs.

[0043] Preferably, in the composite component C, the molar ratio of component D to component E is 1-10:1. The inventors have found that in this preferred case, the obtained hydrophobic VOCs absorbent has higher mass transfer performance and better dynamic absorption effect on VOCs.

[0044] According to the preferred specific embodiment 1, the hydrogen bond donor B is provided by a fatty acid. The molecular formula of the fatty acid is R'-COOH, wherein R' is C n H 2n+1 or C n H 2n-1 , and n is an integer from 7 to 17,

[0045] The hydrogen bond acceptor is provided by at least one of quaternary ammonium salts, menthol, and thymol. The structure of the quaternary ammonium salt is Each R is the same and is selected from an alkyl group of C 4-8 , L is Cl or Br; and the content relationship of each component in the absorbent satisfies formula (I) and formula (II):

[0046] H = A + yB + zC Formula (I),

[0047] A = x1×A1 + x2×A2 + x3×A3 Formula (II);

[0048] 0.5 ≤ y / (x1 + x2 + x3) ≤ 5, 0 < z / (x1 + x2 + x3) ≤ 0.1, and x1, x2, and x3 are not all 0 at the same time.

[0049] According to the preferred specific embodiment 2, when the hydrogen bond donor B is provided by oleic acid, y, z, x1, x2, and x3 respectively satisfy the following conditions: 1 ≤ y / (x1 + x2 + x3) ≤ 5, 0 < z / (x1 + x2 + x3) ≤ 0.1; and x3 is 0, and x1 and x2 are not all 0 at the same time.

[0050] According to the preferred specific embodiment 3, when the hydrogen bond donor B is provided by oleic acid, the quaternary ammonium salt is tetrabutylammonium chloride; y, z, x1, x2, and x3 respectively satisfy the following conditions: x2 and x3 are 0, x1 is not 0, 3x1 ≤ y ≤ 5x1, 0 < z ≤ 0.1x1.

[0051] According to the preferred specific embodiment 4, when the hydrogen bond donor B is provided by oleic acid, y, z, x1, x2, and x3 respectively satisfy the following conditions: x1 and x3 are 0, x2 is not 0, x2 ≤ y ≤ 3x2, 0 < z ≤ 0.1x2.

[0052] According to the preferred specific embodiment 5, when the hydrogen bond donor B is provided by oleic acid, y, z, x1, x2, and x3 respectively satisfy the following conditions: x3 is 0, x1 and x2 are not 0, 2 ≤ y / (x1 + x2) ≤ 5, 0 < z / (x1 + x2) ≤ 0.1. More preferably, when the hydrogen bond donor B is provided by oleic acid, y, z, x1, x2, and x3 respectively satisfy the following conditions: x3 is 0, x1 and x2 are not 0, 2 ≤ y / (x1 + x2) ≤ 5, 0 < z / (x1 + x2) ≤ 0.1, and the ratio between x1 and x2 is 1:0.1 - 2. The inventor found that in this preferred case, the obtained hydrophobic VOC absorbent has a higher absorption capacity for benzene-based VOCs and is more stable under low-temperature conditions.

[0053] According to the preferred specific embodiment 6, when the hydrogen bond donor B is provided by lauric acid, the quaternary ammonium salt is tetrabutylammonium bromide; y, z, x1, x2, and x3 respectively satisfy the following conditions: x2 and x3 are 0, x1 is not 0, 3x1 ≤ y ≤ 5x1, and 0 < z ≤ 0.1x1.

[0054] According to the preferred specific embodiment 7, when the hydrogen bond donor B is provided by n-octanoic acid, y, z, x1, x2, and x3 respectively satisfy the following conditions: x1 and x2 are 0, x3 is not 0, and 0.5x3 ≤ y ≤ 3x3, 0 < z ≤ 0.1x3.

[0055] More preferably, when the hydrogen bond donor B is provided by n-octanoic acid, y, z, x1, x2, and x3 respectively satisfy the following conditions: x1 and x2 are 0, x3 is not 0, and 0.5x3 ≤ y ≤ 2x3, 0 < z ≤ 0.1x3. The inventors found that under this preferred condition, the obtained hydrophobic VOCs absorbent has better mass transfer performance and is more stable under low-temperature conditions.

[0056] As described above, the second aspect of the present invention provides a method for preparing a hydrophobic VOCs absorbent, and the method includes the following steps:

[0057] Performing a first mixing on a hydrogen bond acceptor, a hydrogen bond donor B, and a composite component C to obtain a hydrophobic VOCs absorbent;

[0058] The composite component C is a combination of a component D and a component E; the component D is selected from at least one of toluene and n-hexane; the component E is selected from at least one of acetic acid, lactic acid, and pyruvic acid;

[0059] The hydrogen bond donor B is provided by a fatty acid with the molecular formula R'-COOH, wherein R' is C n H 2n+1 or C n H 2n -1, and n is an integer from 5 to 17.

[0060] The hydrogen bond acceptor is provided by at least one substance selected from quaternary ammonium salts, menthol, and thymol, and the structure of the quaternary ammonium salt is Each R is the same and is selected from an alkyl group of C 4-8 , and L is Cl or Br;

[0061] And the dosage relationship among the hydrogen bond acceptor, the hydrogen bond donor B, and the composite component C satisfies formula (I) and formula (II):

[0062] H = A + yB + zC formula (I),

[0063] A = x1×A1 + x2×A2 + x3×A3 formula (II);

[0064] Among them, the definitions of H, A, y, z, x1, x2, x3, A1, A2, and A3 are correspondingly the same as those described in the first aspect.

[0065] The dosages and types of the respective components involved in the second aspect of the present invention are the same as the contents and types of the corresponding components described in the first aspect of the present invention, and will not be elaborated herein. Those skilled in the art should not understand this as a limitation to the present invention.

[0066] Preferably, in the composite component C, the molar ratio of component D to E is 1 - 10:1.

[0067] Preferably, the first mixing method is selected from at least one of stirring and ultrasonic oscillation.

[0068] Preferably, the first mixing is carried out under stirring conditions, and the conditions for the first mixing at least satisfy: the temperature is 30 - 80°C, and the stirring time is 30 - 90 min. More preferably, for the first mixing carried out under stirring conditions, the conditions for the first mixing at least satisfy: the temperature is 50 - 70°C, and the stirring time is 40 - 80 min.

[0069] It should be noted that the present invention has no special requirements for the rotation speed of the stirring. Those skilled in the art can select according to needs. The specific rotation speed of the stirring is exemplarily listed in the following text of the present invention. Those skilled in the art should not understand this as a limitation to the present invention.

[0070] Preferably, the first mixing is carried out under ultrasonic oscillation conditions, and the conditions for the first mixing at least satisfy: the ultrasonic oscillation time is 20 - 80 min, and the temperature is 30 - 80°C. More preferably, the conditions for the first mixing at least satisfy: the ultrasonic oscillation time is 40 - 70 min, and the temperature is 50 - 70°C.

[0071] The present invention has no special requirements for the frequency of the ultrasonic oscillation, as long as the composite component, hydrogen bond donor, and hydrogen bond ligand can be mixed evenly. Those skilled in the art can select according to needs.

[0072] As described above, the third aspect of the present invention provides a hydrophobic VOCs absorbent prepared by the method described in the second aspect.

[0073] As described above, the fourth aspect of the present invention provides the use of the hydrophobic VOCs absorbent described in the third aspect for absorbing benzene - based VOCs.

[0074] Preferably, the absorption capacity of the absorbent for benzene - based VOCs at 25°C > 50 g / kg. More preferably, the absorption capacity of the absorbent for benzene - based VOCs at 25°C > 200 g / kg.

[0075] In the present invention, the absorption capacity is determined by the saturated solubility measurement method.

[0076] Preferably, the benzene - based VOCs include at least one of toluene, ethylbenzene, and xylene.

[0077] When the hydrophobic VOCs absorbent provided by the present invention is used to absorb benzene - based VOCs, it is in a stable liquid state at the use temperature (10 - 100 °C).

[0078] As described above, the fifth aspect of the present invention provides a method for removing benzene - based VOCs from waste gas. The waste gas is contacted with the hydrophobic VOCs absorbent described in the first aspect and / or the third aspect to obtain a mixture containing benzene - based VOCs.

[0079] Preferably, the waste gas contains 1000 - 10000 ppm of benzene - based VOCs.

[0080] Preferably, the feed volume ratio of the waste gas to the hydrophobic VOC absorbent is 2 - 50:1.

[0081] More preferably, the feed volume ratio of the waste gas to the hydrophobic VOC absorbent is 2 - 20:1. The inventors found that in this preferred case, the absorbent has a better absorption effect and lower energy consumption.

[0082] Preferably, the contact conditions at least satisfy: the contact temperature is 10 - 40 °C, the contact pressure is 0.1 - 0.5 MPa, and the contact time is 0.2 - 2 min.

[0083] The present invention will be described in detail below through examples. In the following examples, the instruments, reagents, materials, etc. involved, unless otherwise specified, are all conventional instruments, reagents, materials, etc. existing in the prior art and can be obtained through regular commercial channels. The experimental methods, detection methods, etc. involved in the following examples, unless otherwise specified, are all conventional experimental methods, detection methods, etc. existing in the prior art.

[0084] Example 1

[0085] The formulation of this example is shown in Table 1 below:

[0086] Table 1

[0087]

[0088] Preparation method of the hydrophobic VOCs absorbent:

[0089] The hydrogen bond acceptor, hydrogen bond donor, and composite component C are first mixed at 300 rpm and 60 °C for 80 min to obtain a hydrophobic VOC absorbent; the saturated vapor pressure of this absorbent at 25 °C is 69 Pa, the saturated water content is 0.92 mol%, and the freezing point is 7.5 °C.

[0090] Example 2

[0091] The formulation of this example is as shown in Table 2 below:

[0092] Table 2

[0093]

[0094] Preparation method of the hydrophobic VOC absorbent:

[0095] The hydrogen bond acceptor, hydrogen bond donor, and composite component C are ultrasonically oscillated at 60 °C under ultrasonic conditions for 60 min to obtain a hydrophobic VOC absorbent. The saturated vapor pressure of this absorbent at 25 °C is 52 Pa, the saturated water content is 0.95%, and the freezing point is 7.2 °C.

[0096] Example 3

[0097] The formulation of this example is as shown in Table 3 below:

[0098] Table 3

[0099]

[0100] Preparation method of the hydrophobic VOC absorbent:

[0101] The hydrogen bond acceptor, hydrogen bond donor, and composite component C are first mixed at 300 rpm and 70 °C for 60 min to obtain a hydrophobic VOC absorbent. The saturated vapor pressure of this absorbent at 25 °C is 78 Pa, the saturated water content is 1.52 mol%, and the freezing point is 6.2 °C.

[0102] Example 4

[0103] A hydrophobic VOC absorbent is prepared in a method similar to that of Example 1 in this example, except that the formulation of the absorbent is different. See Table 4 for details.

[0104] Table 4

[0105]

[0106] The saturated vapor pressure of the absorbent prepared in this example at 25 °C is 79 Pa, the saturated water content is 1.32 mol%, and the freezing point is 8.5 °C.

[0107] Example 5

[0108] In this example, a hydrophobic VOC absorbent was prepared by a method similar to that in Example 1. The difference is that the formulation of the absorbent is different. See Table 5 for details.

[0109] Table 5

[0110]

[0111] The absorbent prepared in this example has a saturated vapor pressure of 59 Pa at 25°C, a saturated water content of 0.86 mol%, and a freezing point of 7.9°C.

[0112] Example 6

[0113] In this example, a hydrophobic VOC absorbent was prepared by a method similar to that in Example 1. The difference is that the formulation of the absorbent is different. See Table 6 for details.

[0114] Table 6

[0115]

[0116] The absorbent prepared in this example has a saturated vapor pressure of 61 Pa at 25°C, a saturated water content of 0.89 mol%, and a freezing point of 8.9°C.

[0117] Example 7

[0118] In this example, a hydrophobic VOC absorbent was prepared by a method similar to that in Example 1. The difference is that the formulation of the absorbent is different. See Table 7 for details.

[0119] Table 7

[0120]

[0121] The absorbent prepared in this example has a saturated vapor pressure of 76 Pa at 25°C, a saturated water content of 1.32 mol%, and a freezing point of 4.2°C.

[0122] Example 8

[0123] In this example, a hydrophobic VOC absorbent was prepared by a method similar to that in Example 1. The difference is that the formulation of the absorbent is different. See Table 8 for details.

[0124] Table 8

[0125]

[0126] The absorbent prepared in this example has a saturated vapor pressure of 88 Pa at 25°C, a saturated water content of 1.63 mol%, and a freezing point of 0.3°C.

[0127] Example 9

[0128] In this example, a hydrophobic VOC absorbent was prepared using a method similar to that of Example 1, except that the amount of oleic acid used in this example was 2 mol;

[0129] The absorbent prepared in this example had a saturated vapor pressure of 60 Pa at 25°C, a saturated water content of 0.88 mol%, and a freezing point of 5.9°C.

[0130] Example 10

[0131] In this example, a hydrophobic VOC absorbent was prepared using a method similar to that of Example 3, except that the amount of oleic acid used in this example was 5 mol;

[0132] The absorbent prepared in this example had a saturated vapor pressure of 87 Pa at 25°C, a saturated water content of 1.66 mol%, and a freezing point of 6.3°C.

[0133] Example 11

[0134] In this example, a hydrophobic VOC absorbent was prepared using a method similar to that of Example 5, except that the amount of lauric acid used in this example was 2 mol;

[0135] The absorbent prepared in this example had a saturated vapor pressure of 48 Pa at 25°C, a saturated water content of 0.95 mol%, and a freezing point of 8.7°C.

[0136] Example 12

[0137] In this example, a hydrophobic VOC absorbent was prepared using a method similar to that of Example 7, except that the amount of n - octanoic acid used in this example was 4 mol;

[0138] The absorbent prepared in this example had a saturated vapor pressure of 72 Pa at 25°C, a saturated water content of 1.42 mol%, and a freezing point of 5.2°C.

[0139] Example 13

[0140] In this example, a hydrophobic VOC absorbent was prepared using a method similar to that of Example 1, except that the amount of n - hexane used in this example was 0.02 mol and the amount of pyruvic acid used was 0.07 mol;

[0141] The absorbent prepared in this example had a saturated vapor pressure of 67 Pa at 25°C, a saturated water content of 0.93 mol%, and a freezing point of 6.5°C.

[0142] Example 14

[0143] In this example, a hydrophobic VOC absorbent was prepared using a method similar to that of Example 1. The difference is that the formulation of the absorbent is different. See Table 9 for details;

[0144] Table 9

[0145]

[0146] The absorbent prepared in this example has a saturated vapor pressure of 69 Pa at 25 °C, a saturated water content of 1.15 mol%, and a freezing point of 5.8 °C.

[0147] Example 15

[0148] In this example, a hydrophobic VOC absorbent was prepared using a method similar to that of Example 1. The difference is that the formulation of the absorbent is different. See Table 10 for details;

[0149] Table 10

[0150]

[0151] The absorbent prepared in this example has a saturated vapor pressure of 85 Pa at 25 °C, a saturated water content of 1.62 mol%, and a freezing point of 3.2 °C.

[0152] Example 16

[0153] In this example, a hydrophobic VOC absorbent was prepared using a method similar to that of Example 1. The difference is that the formulation of the absorbent is different. See Table 11 for details;

[0154] Table 11

[0155]

[0156] The absorbent prepared in this example has a saturated vapor pressure of 65 Pa at 25 °C, a saturated water content of 0.98 mol%, and a freezing point of 6.2 °C.

[0157] Comparative Example 1

[0158] In this comparative example, a hydrophobic VOC absorbent was prepared using a method similar to that of Example 1. The difference is that in this comparative example, only 0.09 mol of n - hexane was used for the composite component C; the remaining steps were the same as those in Example 1.

[0159] The absorbent prepared in this comparative example has a saturated vapor pressure of 89 Pa at 25 °C, a saturated water content of 0.88 mol%, and a freezing point of 8.3 °C.

[0160] Comparative Example 2

[0161] This comparative example used a method similar to that of Example 1 to prepare a hydrophobic VOC absorbent. The difference was that the amount of pyruvic acid used in this comparative example was 0.07 mol; the remaining steps were the same as those in Example 1.

[0162] The absorbent prepared in this comparative example had a saturated vapor pressure of 72 Pa at 25 °C, a saturated water content of 0.97 mol%, and a freezing point of 15.9 °C.

[0163] Comparative Example 3

[0164] This comparative example used a method similar to that of Example 1 to prepare a hydrophobic VOC absorbent. The difference was that the amount of oleic acid used in this comparative example was 8 mol; the remaining steps were the same as those in Example 1.

[0165] The absorbent prepared in this comparative example had a saturated vapor pressure of 124 Pa at 25 °C, a saturated water content of 0.79 mol%, and a freezing point of 6.5 °C.

[0166] Comparative Example 4

[0167] This comparative example used a method similar to that of Example 3 to prepare a hydrophobic VOC absorbent. The difference was that the amount of menthol used in this comparative example was 5 mol; the remaining steps were the same as those in Example 3.

[0168] The absorbent prepared in this comparative example had a saturated vapor pressure of 70 Pa at 25 °C, a saturated water content of 1.56 mol%, and a freezing point of 19.6 °C.

[0169] Comparative Example 5

[0170] This comparative example used a method similar to that of Example 1 to prepare an absorbent. The difference was that the types of hydrogen bond donors of the absorbent in this comparative example were different. See Table 12 for details:

[0171] Table 12

[0172]

[0173] The absorbent prepared in this example had a saturated vapor pressure of 73 Pa at 25 °C, a saturated water content of 1.42 mol%, and a freezing point of 6.2 °C.

[0174] Test Example 1 Absorption Capacity Test

[0175] Under the conditions of 25 °C and 101.3 kPa, benzene-based VOCs (simulated by 80% by volume of toluene, 10% by volume of p-xylene, and 10% by volume of ethylbenzene) were continuously introduced into the hydrophobic VOC absorbent prepared in the above examples. When the VOC content in the absorbent could no longer increase, it was considered to reach absorption saturation, and the absorption amount of benzene-based VOCs at this time was measured as the absorption capacity of the hydrophobic VOC absorbent.

[0176] Test Example 2

[0177] Test on the Removal Effect of Benzene - Series VOCs in Exhaust Gas

[0178] The removal of benzene - series VOCs in the exhaust gas is completed in a packed absorption tower. The exhaust gas contains 99 vol% of nitrogen, 0.8 vol% of toluene, 0.1 vol% of p - xylene, and 0.1 vol% of ethylbenzene. The packing is φ3mm Raschig rings, and the theoretical number of stages is 20. The exhaust gas and the hydrophobic VOC absorbent flow into the packed absorption tower from the lower end and the upper end respectively, and the feed volume ratio of the exhaust gas to the hydrophobic VOC absorbent is 10:1.

[0179] The exhaust gas and the hydrophobic VOC absorbent are in counter - current contact in the absorption tower. The conditions of the contact are as follows: the contact temperature is 25°C, the contact pressure is 0.1 MPa, and the contact time is 0.5 min.

[0180] After absorption, the absorbent liquid is discharged from the bottom of the packed absorption tower. The purified gas is discharged from the top of the packed absorption tower. A detection device equipped with a flame ionization detector or a photoionization detector is used to detect the content of benzene - series VOCs, and the removal rates R of toluene, p - xylene, and ethylbenzene are calculated.

[0181] R 甲苯 =(x in,甲苯 - x out,甲苯 ) / x in,甲苯 ×100%

[0182] R 对二甲苯 =(x in,对二甲苯 - x out,对二甲苯 ) / x in,对二甲苯 ×100%

[0183] R 乙苯 =(x in,乙苯 - x out,乙苯 ) / x in,乙苯 ×100%

[0184] Among them, x in represents the volume of benzene - series VOCs in the exhaust gas per unit time, and x out represents the volume of benzene - series VOCs in the purified gas per unit time.

[0185] The specific test data are shown in Table 13 below.

[0186] Table 13

[0187]

[0188]

[0189] As can be seen from the above results, the hydrophobic VOC absorbent provided by the present invention has the advantages of high absorption capacity for benzene-based VOCs, low saturated vapor pressure, and good stability at low temperatures; and the removal rate of benzene-based VOCs (toluene, xylene, ethylbenzene) in the waste gas by the absorbent is above 97.0%, indicating its excellent mass transfer performance and good dynamic absorption effect.

[0190] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A hydrophobic VOCs absorbent, characterized in that, The absorbent has a saturated vapor pressure of less than 100 Pa at 25 °C, a saturated water content of less than 2 mol%, and a freezing point of less than 10 °C; the absorbent contains a hydrogen bond donor B, a hydrogen bond acceptor, and a composite component C. The composite component C is a combination of component D and component E; component D is selected from at least one of toluene and n-hexane; component E is selected from at least one of acetic acid, lactic acid, and pyruvic acid. The hydrogen bond donor B is provided by a fatty acid with the molecular formula R'-COOH, where R' is C n H 2n+1 or C n H 2n-1 , and n is an integer from 5 to 17. The hydrogen bond acceptor is provided by at least one of quaternary ammonium salts, menthol, and thymol, and the structure of the quaternary ammonium salt is Each R is the same and is selected from C 4-8 alkyl group, and L is Cl or Br; And the content relationship of each component in the absorbent satisfies formula (I) and formula (II): H = A + yB + zC formula (I), A = x1×A1 + x2×A2 + x3×A3 formula (II); y, z, x1, x2, x3 respectively satisfy the following conditions: 0.5 ≤ y / (x1 + x2 + x3) ≤ 5, 0 < z / (x1 + x2 + x3) ≤ 0.1, x1, x2, x3 are not all 0. H represents the total amount of components of the absorbent, A represents the total amount of hydrogen bond acceptors, y represents the amount of substance of hydrogen bond donor B, z represents the total amount of substance of composite component C, x1 represents the amount of substance of quaternary ammonium salt A1, x2 represents the amount of substance of menthol A2, x3 represents the amount of substance of thymol A3, and the amount of substance units of y, z, x1, x2, x3 are the same.

2. The absorbent according to claim 1, wherein The hydrogen bond donor B is provided by a fatty acid, and the molecular formula of the fatty acid is R'-COOH, where R' is C n H 2n+1 or C n H 2n -1, and n is an integer from 7 to 17. The hydrogen bond acceptor is provided by at least one of quaternary ammonium salts, menthol, and thymol, and the structure of the quaternary ammonium salt is Each R is the same and is selected from C 4-8 alkyl groups, L is Cl or Br; and the content relationship of each component in the absorbent satisfies formula (I) and formula (II): H = A + yB + zC formula (I), A = x1×A1 + x2×A2 + x3×A3 formula (II); 0.5 ≤ y / (x1 + x2 + x3) ≤ 5, 0 < z / (x1 + x2 + x3) ≤ 0.1, x1, x2, x3 are not all 0.

3. The absorbent according to claim 1 or 2, wherein, In the composite component C, the molar ratio of component D to component E is 1 - 10:

1.

4. The absorbent according to claim 1 or 2, wherein The hydrogen bond donor B is provided by oleic acid, and y, z, x1, x2, x3 respectively satisfy the following conditions: 1 ≤ y / (x1 + x2 + x3) ≤ 5, 0 < z / (x1 + x2 + x3) ≤ 0.1; and x3 is 0, x1, x2 are not all 0.

5. The absorbent according to any one of claims 1-3, wherein, The hydrogen bond donor B is provided by oleic acid, and the quaternary ammonium salt is tetrabutylammonium chloride. y, z, x1, x2, x3 respectively satisfy the following conditions: x2, x3 are 0, x1 is not 0, 3x1 ≤ y ≤ 5x1, 0 < z ≤ 0.1x1.

6. The absorbent according to any one of claims 1-3, wherein, The hydrogen bond donor B is provided by oleic acid. y, z, x1, x2, x3 respectively satisfy the following conditions: x1, x3 are 0, x2 is not 0, x2 ≤ y ≤ 3x2, 0 < z ≤ 0.1x2.

7. The absorbent according to any one of claims 1-3, wherein, The hydrogen bond donor B is provided by oleic acid. y, z, x1, x2, x3 respectively satisfy the following conditions: x3 is 0, x1, x2 are not 0, 2 ≤ y / (x1 + x2) ≤ 5, 0 < z / (x1 + x2) ≤ 0.

1.

8. The absorbent according to claim 1 or 2, wherein The hydrogen bond donor B is provided by lauric acid, and the quaternary ammonium salt is tetrabutylammonium bromide. y, z, x1, x2, x3 respectively satisfy the following conditions: x2, x3 are 0, x1 is not 0, 3x1 ≤ y ≤ 5x1, 0 < z ≤ 0.1x1.

9. The absorbent according to claim 1 or 2, wherein The hydrogen bond donor B is provided by n-octanoic acid. y, z, x1, x2, x3 respectively satisfy the following conditions: x1, x2 are 0, x3 is not 0, and 0.5x3 ≤ y ≤ 3x3, 0 < z ≤ 0.1x3; Preferably, y, z, x1, x2, and x3 respectively satisfy the following conditions: x1 and x2 are 0, x3 is not 0, and 0.5x3 ≤ y ≤ 2x3, 0 < z ≤ 0.1x3.

10. A preparation method of a hydrophobic VOCs absorbent, characterized in that, The method includes the following steps: Performing a first mixing on a hydrogen bond acceptor, a hydrogen bond donor B, and a composite component C to obtain a hydrophobic VOCs absorbent; The composite component C is a combination of a component D and a component E; the component D is selected from at least one of toluene and n-hexane; the component E is selected from at least one of acetic acid, lactic acid, and pyruvic acid; The hydrogen bond donor B is provided by a fatty acid with the molecular formula R'-COOH, where R' is C n H 2n+1 or C n H 2n-1 , and n is an integer from 5 to 17. The hydrogen bond acceptor is provided by at least one substance selected from quaternary ammonium salts, menthol, and thymol, and the structure of the quaternary ammonium salt is Each R is the same and is selected from C 4-8 alkyl groups, and L is Cl or Br; And the dosage relationship among the hydrogen bond acceptor, the hydrogen bond donor B, and the composite component C satisfies formula (I) and formula (II): H = A + yB + zC formula (I), A = x1×A1 + x2×A2 + x3×A3 formula (II); Wherein, the definitions of H, A, y, z, x1, x2, x3, A1, A2, and A3 are the same as those defined in any one of claims 1-9.

11. The method according to claim 10, wherein, The first mixing method is stirring; the conditions of the first mixing at least satisfy: the temperature is 30-80°C, and the stirring time is 30-90 min.

12. The method according to claim 10, wherein, The first mixing method is ultrasonic oscillation; the conditions of the first mixing at least satisfy: the ultrasonic oscillation time is 20-80 min, and the temperature is 30-80°C.

13. A hydrophobic VOCs absorbent prepared by the method according to any one of claims 10-12.

14. The hydrophobic VOCs absorbent according to any one of claims 1-9 and claim 13 is used for absorbing benzene-based VOCs.

15. The application according to claim 14, wherein, The absorption capacity of the hydrophobic VOCs absorbent for benzene-based VOCs at 25°C > 50 g / kg; Preferably, the absorption capacity of the hydrophobic VOCs absorbent for benzene-based VOCs at 25°C > 200 g / kg; Preferably, the benzene-based VOCs include at least one of toluene, ethylbenzene, and xylene.

16. A method for removing benzene-based VOCs from waste gas, characterized in that, Bringing the waste gas into contact with the hydrophobic VOCs absorbent to obtain a mixture containing benzene-based VOCs; The hydrophobic VOCs absorbent is the hydrophobic VOCs absorbent according to any one of claims 1-9 and 13.

17. The method according to claim 16, wherein The feed volume ratio of the waste gas to the hydrophobic VOC absorbent is 2-50:1; preferably 2-20:1; Preferably, the contact conditions at least satisfy: the contact temperature is 10-40°C, the contact pressure is 0.1-0.5 MPa, and the contact time is 0.2-2 min.

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