Hydrophobic activated carbon as well as preparation method and application thereof

Abstract

The invention relates to the technical field of VOCs treatment, and discloses hydrophobic activated carbon and a preparation method and application thereof.The method comprises the steps that formed activated carbon is dried and then mixed with a short-chain polymer and an organic solvent, then rotary evaporation drying and vacuum drying are conducted, and the hydrophobic activated carbon is obtained; the short-chain polymer is selected from poly (butyl acrylate), polyvinyl acetate, polylactic acid, polysiloxane, polyethylene, polypropylene, polyisobutene, polystyrene, poly (4-tert-butylstyrene), polybutadiene, polyvinyl ether, polyvinyl formal, polyvinyl carbonate, polyepichlorohydrin, polyethyleneimine and polyetherimide; the component A is at least one of polymethyl isopropyl ether and polyglycolide. The formed activated carbon is used as a modification starting point, the short-chain polymer is used as a modifier, and through specific selection of the short-chain polymer and rotary evaporation drying and vacuum drying, the prepared hydrophobic activated carbon is excellent in hydrophobic performance and excellent in adsorption effect on VOCs in high-humidity crude oil volatile gas.

Description

Technical Field

[0001] The present invention relates to the technical field of VOCs treatment, and particularly relates to a hydrophobic activated carbon, a preparation method thereof and an application thereof. Background Art

[0002] During the exploitation, storage and transportation of crude oil in oil fields, the emission of VOCs will inevitably occur. In order to reduce environmental pollution and improve the efficiency of oil fields, it is urgent to effectively recover and utilize the volatile gas of crude oil. The main VOCs treatment technologies include adsorption method, liquid absorption method, condensation method, combustion method, biological method, plasma method, etc. The adsorption technology is a simple and practical VOCs treatment technology, which can not only effectively treat VOCs, solve the environmental pollution problem, but also recover VOCs and create considerable economic benefits. The water content in the volatile gas of crude oil is relatively high, and the presence of water vapor will affect the adsorption of oil and gas. The core of the adsorption technology is a porous solid adsorbent material. Currently, the commonly used adsorbents include zeolite / molecular sieve, silica gel, activated carbon, etc. Among them, activated carbon has the advantages of large specific surface area, developed pore structure, strong adsorption capacity, etc., and is the most widely used. However, a large number of water molecules in the volatile gas of crude oil greatly affect the adsorption and recovery ability of activated carbon for VOCs. Therefore, how to reduce the influence of water molecules on the adsorption of VOCs by activated carbon is particularly important. For this reason, there is an urgent need to develop a method for preparing hydrophobic activated carbon for the adsorption and recovery of high-humidity crude oil volatile gas. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problem that the moisture in the high-humidity crude oil volatile gas in the prior art greatly affects the adsorption capacity of activated carbon for VOCs, resulting in poor adsorption and recovery effect of VOCs, and to provide a hydrophobic activated carbon for treating high-humidity crude oil volatile gas, a preparation method thereof and an application thereof.

[0004] In order to achieve the above purpose, on the one hand, the present invention provides a preparation method of a hydrophobic activated carbon, which includes: drying the formed activated carbon, then mixing it with a short-chain polymer and an organic solvent, and then performing rotary evaporation drying and vacuum drying;

[0005] Wherein, the weight-average molecular weight of the short-chain polymer is 1000-50000;

[0006] The short-chain polymer is selected from one or more of butyl acrylate, polyvinyl acetate, polylactic acid, polysiloxane, polyethylene, polypropylene, polyisobutene, polystyrene, poly(4-tert-butylstyrene), polybutadiene, polyvinyl ethyl ether, polyvinyl formal, polycarbonate ethylene ester, epichlorohydrin, polyethyleneimine, polyetherimide, polymethyl isopropyl ether and polyglycolide.

[0007] Preferably, the shaped activated carbon is in the form of columnar particles with a diameter of 2 - 6 mm and a length of 2 - 7 mm.

[0008] Preferably, the specific surface area of the shaped activated carbon is 1200 - 1300 m 2 / g, and the average pore diameter is 0.5 - 5 nm.

[0009] Preferably, the size of the short-chain polymer is larger than the pore diameter of the shaped activated carbon.

[0010] Preferably, the weight-average molecular weight of the short-chain polymer is 1000 - 50000, preferably 1000 - 10000.

[0011] Preferably, the weight ratio of the amount of the short-chain polymer to the shaped activated carbon is 1:10 - 200, preferably 1:40 - 100.

[0012] Preferably, the dosage ratio of the shaped activated carbon to the organic solvent is 5 - 20 g:100 mL.

[0013] Preferably, the organic solvent is selected from one or more of methanol, ethanol, propanol, dichloromethane, and chloroform.

[0014] Preferably, when drying the shaped activated carbon, the drying conditions include: a temperature of 80 - 150 °C and a time of 2 - 15 h.

[0015] Preferably, the mixing process specifically includes:

[0016] (1) Mix the short-chain polymer and the organic solvent to obtain a first solution;

[0017] (2) Immerse the dried shaped activated carbon in the first solution, stir and mix, ultrasonically oscillate, soak statically, and then heat with microwave.

[0018] Preferably, in step (2), the stirring and mixing time is 0.5 - 2 h.

[0019] Preferably, in step (2), the ultrasonic oscillation conditions include: a frequency of 40 - 100 KHz and a time of 0.5 - 5 h.

[0020] Preferably, in step (2), the static soaking time is 1 - 24 h.

[0021] Preferably, the microwave heating conditions include: a power of 500 - 800 W, a temperature of 40 - 70 °C, and a time of 0.5 - 2 h.

[0022] Preferably, in step (2), the conditions for microwave heating include: power of 500 - 800 W, temperature of 40 - 70 °C, and time of 0.5 - 2 h.

[0023] Preferably, the temperature for rotary evaporation drying is 30 - 60 °C, and the time is 0.2 - 2 h.

[0024] Preferably, the temperature for vacuum drying is 60 - 120 °C, and the time is 4 - 24 h.

[0025] In the second aspect of the present invention, a hydrophobic activated carbon prepared by the method as described above is provided.

[0026] Preferably, the specific surface area of the hydrophobic activated carbon is 800 - 1210 m 2 / g, and the surface contact angle with water is greater than 100°.

[0027] In the third aspect of the present invention, an application of the hydrophobic activated carbon as described above in adsorbing VOCs in crude oil volatile gas is provided.

[0028] In the technical solution provided by the present invention, starting from shaped activated carbon as the modification starting point, using short-chain polymers as modifiers, and through the specific selection of short-chain polymers and rotary evaporation drying + vacuum drying, the prepared hydrophobic activated carbon has excellent hydrophobic properties and excellent adsorption effect on VOCs in high-humidity crude oil volatile gas; in addition, the present invention uses green short-chain polymers as modifiers, which are safe and environmentally friendly, and avoid the environmental damage and health hazards of halogenated silane modifiers. Description of the Drawings

[0029] Figure 1 is the nitrogen adsorption - desorption isotherm of unmodified shaped activated carbon. Detailed Embodiments

[0030] The following further details the specific embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0031] In the ranges disclosed herein, the endpoints and any values 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 and individual point values of each range, 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.

[0032] The present invention provides a method for preparing a hydrophobic activated carbon, which includes: drying the shaped activated carbon, then mixing it with a short-chain polymer and an organic solvent, and then performing rotary evaporation drying and vacuum drying;

[0033] Among them, the weight-average molecular weight of the short-chain polymer is 1000-50000;

[0034] The short-chain polymer is selected from one or more of butyl acrylate, polyvinyl acetate, polylactic acid, polysiloxane, polyethylene, polypropylene, polyisobutylene, polystyrene, poly(4-tert-butylstyrene), polybutadiene, polyvinyl ethyl ether, polyvinyl formal, poly(ethylene carbonate), epichlorohydrin polymer, polyethyleneimine, polyetherimide, polymethyl isopropyl ether, and polyglycolide.

[0035] In the method of the present invention, a short-chain polymer is used as a modifier. The short-chain polymer forms a highly dispersed hydrophobic barrier on the surface of the shaped activated carbon, enhancing the moisture resistance and competitive affinity of the shaped activated carbon surface for VOCs in a humid environment, thereby improving the VOCs adsorption effect. At the same time, the rotary evaporation method is first used to remove most of the organic solvents to make it apparently dry, and then vacuum drying is used for deep drying, so that the polymer in the solvent is more fully and uniformly coated on the surface of the shaped activated carbon.

[0036] The present invention uses shaped activated carbon as a raw material. On the one hand, the surface area of the shaped activated carbon is smaller, and the modifier only needs to perform hydrophobic modification on the particle surface, reducing the dosage and having a higher effective utilization rate. On the other hand, it can avoid the serious problem of pore structure loss caused by regranulation after hydrophobic modification of powdered activated carbon, and retains the initial pore structure of the activated carbon as much as possible, resulting in less pore structure loss. By using the above-mentioned green short-chain polymer as a modifier, it is safe, environmentally friendly, avoids the environmental damage and health hazards of halogenated silane modifiers, and has good hydrophobic modification effect. In addition, at present, hydrophobic activated carbon is mostly prepared by suction filtration + vacuum drying. The present invention evaporates the solvent by rotary evaporation drying instead of the conventional suction filtration method to filter the solvent, enabling the polymer in the solvent to be fully coated on the surface of the shaped activated carbon, avoiding the loss of the polymer with the filtration of the solvent, and enabling the polymer to be evenly distributed on the surface of the shaped activated carbon. Therefore, the hydrophobic activated carbon prepared by the present invention has excellent hydrophobic performance and excellent adsorption effect on VOCs in high-humidity crude oil volatile gas.

[0037] In the present invention, the shaped activated carbon refers to a granular product obtained by extruding powdered activated carbon. The present invention does not limit the specific source of the shaped activated carbon, which can be self-prepared or purchased, as long as it is a granular activated carbon that does not require further extrusion granulation treatment. In a preferred embodiment, the shaped activated carbon is a columnar particle with a diameter of 2-6 mm and a length of 2-7 mm. More preferably, the diameter of the columnar shaped activated carbon is 3-5 mm and the length is 3-6 mm.

[0038] In a preferred embodiment, the specific surface area of the formed activated carbon is 1200-1300 m 2 / g, and the average pore diameter is 0.5-5 nm.

[0039] In a preferred embodiment, the short-chain polymer is polyethyleneimine and / or polystyrene.

[0040] In a preferred embodiment, the size (diameter) of the short-chain polymer is larger than the pore diameter of the formed activated carbon, so that the short-chain polymer cannot enter the pore channels of the formed activated carbon, thereby avoiding the problem of pore blockage of the activated carbon caused by the modifier and minimizing the loss of the pore structure of the activated carbon.

[0041] In a preferred embodiment, the weight-average molecular weight (Mw) of the short-chain polymer is 1000-20000, more preferably 1000-10000. Within the above weight-average molecular weight range, the short-chain polymer will not enter the pore channels of the formed activated carbon, and the polymer is more uniformly dispersed on the surface of the formed activated carbon.

[0042] When the dosage of the short-chain polymer is too much, it will block the entrance of the pore channels on the surface of the formed activated carbon and affect the adsorption performance of VOCs. When the dosage of the short-chain polymer is too little, the hydrophobic modification effect is poor. Considering the comprehensive factors of the hydrophobic modification effect and the loss of the pore structure, in a preferred embodiment, the weight ratio of the short-chain polymer to the formed activated carbon is 1:10-200, preferably 1:40-100. Within the above dosage ratio range, the formed activated carbon has a better hydrophobic effect and a smaller loss of the pore structure, so that the prepared hydrophobic activated carbon has a better adsorption effect on VOCs in the volatile gas of crude oil. Specifically, the weight ratio of the short-chain polymer to the formed activated carbon can be, for example, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90 or 1:100.

[0043] The present invention does not limit the dosage of the organic solvent, as long as its dosage is higher than the stacking height of the formed activated carbon, that is, during mixing, it is necessary to ensure that the formed activated carbon is completely immersed. In a preferred embodiment, the dosage ratio of the formed activated carbon to the organic solvent is 5-20 g:100 mL.

[0044] In a preferred embodiment, the organic solvent is selected from one or more of methanol, ethanol, propanol, dichloromethane and chloroform.

[0045] The present invention does not limit the specific conditions for drying the formed activated carbon. In a preferred embodiment, the drying conditions include: the temperature is 80-150 °C and the time is 2-15 h.

[0046] In a preferred embodiment, the mixing process specifically includes:

[0047] (1) Mix the short-chain polymer and the organic solvent to obtain a first solution;

[0048] (2) Immerse the dried formed activated carbon in the first solution, stir and mix, ultrasonically oscillate, soak statically, and then heat by microwave.

[0049] In the present invention, through ultrasonic oscillation treatment, the short-chain polymer can more uniformly surround the formed activated carbon, making the hydrophobic modification of the formed activated carbon sufficient and the surface hydrophobic layer uniform without holes; through microwave heating treatment, the movement of short-chain polymer molecules on the surface of the formed activated carbon can be increased, making the hydrophobic modification of the hydrophobic activated carbon more sufficient, and further making the hydrophobic effect of the prepared hydrophobic activated carbon better.

[0050] In a preferred embodiment, in step (2), the time for the stirring and mixing is 0.5 to 2 h. Specifically, for example, it can be 0.5 h, 1 h, 1.2 h, 1.5 h, 1.8 h, or 2 h.

[0051] In a preferred embodiment, in step (2), the conditions for the ultrasonic oscillation include: a frequency of 40 to 100 KHz and a time of 0.5 to 5 h.

[0052] In a preferred embodiment, in step (2), the time for the static soaking is 1 to 24 h, preferably 12 to 24 h. Specifically, for example, it can be 12 h, 14 h, 15 h, 16 h, 17 h, 18 h, 20 h, 22 h, 23 h, or 24 h.

[0053] In a preferred embodiment, in step (2), the conditions for the microwave heating include: a power of 500 to 800 W, a temperature of 40 to 70 °C, and a time of 0.5 to 2 h.

[0054] In a preferred embodiment, the temperature for the rotary evaporation is 30 to 60 °C. Specifically, for example, it can be 30 °C, 40 °C, 42 °C, 45 °C, 47 °C, 50 °C, 55 °C, 57 °C, or 60 °C.

[0055] The present invention does not limit the time for the rotary evaporation, as long as most of the solvent soaking the activated carbon can be evaporated to make the activated carbon appear dry. Preferably, the time for the rotary evaporation is 0.2 to 2 h.

[0056] In a preferred embodiment, the temperature for the vacuum drying is 60 to 120 °C. Specifically, for example, it can be 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, or 120 °C.

[0057] In a preferred embodiment, the time for vacuum drying is 4 to 24 h. Specifically, for example, it can be 4 h, 5 h, 6 h, 10 h, 12 h, 15 h, 18 h, 20 h or 24 h.

[0058] In the method of the present invention, a green and environmentally friendly short-chain polymer is used as a hydrophobic modifier to hydrophobically modify the shaped activated carbon. It is prepared by liquid-phase impregnation (ultrasonic oscillation + static soaking), microwave heating, rotary evaporation drying, and vacuum deep drying, so that the prepared hydrophobic layer is more uniformly dispersed and the pore structure is better maintained, thereby further improving the hydrophobic performance of the hydrophobic activated carbon and the adsorption effect on VOCs in high-humidity crude oil volatile gas.

[0059] The present invention also provides a hydrophobic activated carbon prepared by the method as described above.

[0060] The hydrophobic activated carbon has excellent hydrophobic effect and can be applied to the field of adsorption and recovery of crude oil volatile gas in oil fields to improve the recovery efficiency of crude oil volatile gas.

[0061] In a preferred embodiment, the specific surface area of the hydrophobic activated carbon is 800 - 1210 m 2 / g, and the surface contact angle with water is greater than 100°.

[0062] The present invention also provides an application of the hydrophobic activated carbon as described above in adsorbing VOCs in crude oil volatile gas, especially in adsorbing VOCs in high-humidity crude oil volatile gas.

[0063] The present invention will be described in detail below through examples, but the protection scope of the present invention is not limited thereto. In the following examples and comparative examples, unless otherwise specified, they are all commercially available products.

[0064] In the following examples and comparative examples, some of the raw materials involved are as follows:

[0065] The shaped activated carbon was purchased from Qingdao Guanbaolin Activated Carbon Co., Ltd., with a specific surface area of 1269 m 2 / g, an average pore diameter of 0.96 nm. It is a columnar granular activated carbon with a diameter of 3 mm and a length of 3 - 6 mm;

[0066] The short-chain polymer was purchased from Shanghai Macklin Biochemical Co., Ltd. The molecular weights of the short-chain polymers are as follows: polyethyleneimine M W 1800, polystyrene M W 4000, polystyrene M W 50000, polystyrene M W 500; among them, polyethyleneimine M W 1800, polystyrene M W 4000 and polystyrene MW The sizes of 50000 are all larger than the pore diameters of the formed activated carbon.

[0067] In the following examples and comparative examples, room temperature refers to 25 °C.

[0068] In the following examples and comparative examples, the test methods involved are as follows:

[0069] (1) Test of specific surface area

[0070] The specific surface areas of the formed activated carbon and hydrophobic modified activated carbon, etc. are determined by a physical adsorption instrument using the low-temperature nitrogen adsorption method.

[0071] (2) Test of water contact angle

[0072] Use a micro syringe to measure 5 μL of distilled water and drop it on the surface of the formed activated carbon after hydrophobic modification. Use a JY-PHb type contact angle measuring instrument. By adjusting the height of the platform to make the interface flush with the baseline and adjusting the light source and camera focal length, obtain a water droplet image with obvious black and white contrast, clear and smooth outline. In this experiment, the height measurement method is used to measure the angle. The measurement results need to be measured at three different positions on the surface of the activated carbon and the average value is taken. The final contact angle value is the average value of the measurement results at different positions.

[0073] (3) Test of adsorption performance

[0074] Use a breakthrough adsorption instrument to measure the dynamic adsorption capacity of activated carbon for propane. Under the condition of 298 K, a mixed gas (at atmospheric pressure) of 300 ml / min gas flow rate, 300 ppm propane and 30% water vapor is introduced into the inlet. Nitrogen is used as the balance gas, and a VOCs measuring instrument is used to measure the propane concentration at the outlet; when the propane concentration approaches 80% of the inlet concentration, stop the adsorption experiment. The dynamic adsorption capacity of the gas is calculated from the breakthrough curve using the following formula:

[0075]

[0076] In the formula, Q n吸附 is the adsorption capacity of the adsorbent for adsorbate n, in ml; Q n入总 is the total flow rate of adsorbate n flowing into the breakthrough column within ΔT, in ml; Q n出总 is the total flow rate of adsorbate n flowing out of the breakthrough column within ΔT, in ml; V 总入 is the total gas flow rate at the inlet of the breakthrough column, in ml / min; V 载气 is the carrier gas flow rate, in ml / min; C n0 is the percentage concentration (%) of adsorbate n at the inlet of the breakthrough column; C nt is the percentage concentration (%) of adsorbate n at a certain moment at the outlet of the breakthrough column; △T is the total duration from the start to the end of adsorption (unit: s).

[0077] Example 1

[0078] Weigh 10 g of shaped activated carbon and place it in an oven at 120 °C for heating and drying for 12 h; weigh 0.08 g of short-chain polymer (polyethyleneimine M W 1800), dissolve it in 100 ml of ethanol, stir evenly to obtain the first solution (that is, the weight ratio of the short-chain polymer to the shaped activated carbon is 1:125); immerse the dried shaped activated carbon in the first solution, and stir and mix at room temperature for 2 h; then ultrasonically oscillate at a power of 40 Hz for 1 h, and then let it stand and soak for 12 h; put the obtained mixture into a 600 W microwave oven and heat it at 40 °C for 2 h.

[0079] After microwave heating, use a rotary evaporator to spin-dry at 30 °C for 1 h to make the activated carbon appear dry; place the obtained roughly dried activated carbon sample in a vacuum drying oven at 60 °C for deep drying for 24 h to prepare hydrophobic activated carbon and store it in a desiccator.

[0080] Example 2

[0081] Weigh 10 g of shaped activated carbon and place it in an oven at 120 °C for heating and drying for 12 h; weigh 0.1 g of short-chain polymer (polyethyleneimine M W 1800), dissolve it in 100 ml of ethanol, stir evenly to obtain the first solution (that is, the weight ratio of the short-chain polymer to the shaped activated carbon is 1:100); immerse the dried shaped activated carbon in the first solution, and stir and mix at room temperature for 1 h; then ultrasonically oscillate at a power of 40 Hz for 1.5 h, and then let it stand and soak for 18 h; put the obtained mixture into a 600 W microwave oven and heat it at 55 °C for 1 h.

[0082] After microwave heating, use a rotary evaporator to spin-dry at 45 °C for 0.5 h to make the activated carbon appear dry; place the obtained roughly dried activated carbon sample in a vacuum drying oven at 90 °C for deep drying for 12 h to prepare hydrophobic activated carbon and store it in a desiccator.

[0083] Example 3

[0084] Weigh 10 g of shaped activated carbon and place it in an oven at 120 °C for heating and drying for 12 h; weigh 0.2 g of short-chain polymer (polyethyleneimine M WWeigh 10 g of the shaped activated carbon and heat it in an oven at 120 °C for 12 h. Weigh 0.2 g of the short-chain polymer (polystyrene M

[0085] After microwave heating, rotary evaporation is carried out at 60 °C for 1 h using a rotary evaporator to make the activated carbon appear dry; the obtained roughly dried activated carbon sample is placed in a vacuum drying oven at 120 °C for deep drying for 4 h to prepare the hydrophobic activated carbon, which is then stored in a desiccator.

[0086] Example 4

[0087] Weigh 10 g of the shaped activated carbon and heat it in an oven at 120 °C for 12 h. Weigh 0.08 g of the short-chain polymer (polystyrene M W 4000), dissolve it in 100 ml of ethanol, stir evenly to obtain the first solution (that is, the weight ratio of the short-chain polymer to the shaped activated carbon used is 1:125); immerse the dried shaped activated carbon in the first solution, stir and mix at room temperature for 2 h; then carry out ultrasonic oscillation at a power of 40 Hz for 1 h, and then let it stand and soak for 12 h; put the obtained mixture into a 600 W microwave oven and heat it at 40 °C for 2 h.

[0088] After microwave heating, rotary evaporation is carried out at 30 °C for 0.5 h using a rotary evaporator to make the activated carbon appear dry; the obtained roughly dried activated carbon sample is placed in a vacuum drying oven at 60 °C for deep drying for 24 h to prepare the hydrophobic activated carbon, which is then stored in a desiccator.

[0089] Example 5

[0090] Weigh 10 g of the shaped activated carbon and heat it in an oven at 120 °C for 12 h; weigh 0.1 g of the short-chain polymer (polystyrene M W 4000), dissolve it in 100 ml of ethanol, stir evenly to obtain the first solution (that is, the weight ratio of the short-chain polymer to the shaped activated carbon used is 1:100); immerse the dried shaped activated carbon in the first solution, stir and mix at room temperature for 1 h; then carry out ultrasonic oscillation at a power of 40 Hz for 1.5 h, and then let it stand and soak for 18 h; put the obtained mixture into a 600 W microwave oven and heat it at 55 °C for 1 h.

[0091] After microwave heating, rotary evaporation is carried out at 45 °C for 1 h using a rotary evaporator to make the activated carbon appear dry. The obtained roughly dried activated carbon sample is placed in a vacuum drying oven at 90 °C for deep drying for 12 h to prepare hydrophobic activated carbon, which is then stored in a desiccator.

[0092] Example 6

[0093] Weigh 10 g of shaped activated carbon and heat it in an oven at 120 °C for 12 h; weigh 0.2 g of short-chain polymer (polystyrene M W 4000), dissolve it in 100 ml of ethanol, stir evenly to obtain a first solution (that is, the weight ratio of the short-chain polymer to the shaped activated carbon used is 1:50); immerse the dried shaped activated carbon in the first solution, stir and mix at room temperature for 0.5 h; then ultrasonically oscillate at a power of 40 Hz for 2 h, and then let it stand and soak for 24 h; put the obtained mixture into a 600 W microwave oven and heat it at 70 °C for 0.5 h.

[0094] After microwave heating, rotary evaporation is carried out at 60 °C for 0.5 h using a rotary evaporator to make the activated carbon appear dry. The obtained roughly dried activated carbon sample is placed in a vacuum drying oven at 120 °C for deep drying for 4 h to prepare hydrophobic activated carbon, which is then stored in a desiccator.

[0095] Example 7

[0096] Weigh 10 g of shaped activated carbon and heat it in an oven at 120 °C for 12 h; weigh 0.2 g of short-chain polymer (polystyrene M W 50000), dissolve it in 100 ml of ethanol, stir evenly to obtain a first solution (that is, the weight ratio of the short-chain polymer to the shaped activated carbon used is 1:50); immerse the dried shaped activated carbon in the first solution, stir and mix at room temperature for 0.5 h; then ultrasonically oscillate at a power of 40 Hz for 2 h, and then let it stand and soak for 24 h; put the obtained mixture into a 600 W microwave oven and heat it at 70 °C for 0.5 h.

[0097] After microwave heating, rotary evaporation is carried out at 60 °C for 1 h using a rotary evaporator to make the activated carbon appear dry. The obtained roughly dried activated carbon sample is placed in a vacuum drying oven at 120 °C for deep drying for 4 h to prepare hydrophobic activated carbon, which is then stored in a desiccator.

[0098] Example 8

[0099] The method described in Example 6 is carried out, except that the weight ratio of the short-chain polymer to the shaped activated carbon used is 1:40.

[0100] Specifically as follows:

[0101] Weigh 10 g of the formed activated carbon and heat it in an oven at 120 °C for 12 h of drying; weigh 0.25 g of the short-chain polymer (polystyrene M W 4000), dissolve it in 100 ml of ethanol, stir evenly to obtain the first solution (that is, the weight ratio of the short-chain polymer to the formed activated carbon used is 1:40); immerse the dried formed activated carbon in the first solution, and stir and mix at room temperature for 0.5 h; then perform ultrasonic oscillation at a power of 40 Hz for 2 h, and then let it stand and soak for 24 h; put the obtained mixture into a 600 W microwave oven and heat it at 70 °C for 0.5 h.

[0102] After microwave heating, use a rotary evaporator to perform rotary evaporation and drying at 60 °C for 0.5 h to make the activated carbon appear dry. Place the obtained roughly dried activated carbon sample in a vacuum drying oven at 120 °C for 4 h of deep drying to prepare the hydrophobic activated carbon and store it in a desiccator.

[0103] Example 9

[0104] Carry out the implementation according to the method described in Example 6, the difference is that the ultrasonic oscillation step is removed.

[0105] Specifically as follows:

[0106] Weigh 10 g of the formed activated carbon and heat it in an oven at 120 °C for 12 h of drying; weigh 0.2 g of the short-chain polymer (polystyrene M W 4000), dissolve it in 100 ml of ethanol, stir evenly to obtain the first solution (that is, the weight ratio of the short-chain polymer to the formed activated carbon used is 1:50); immerse the dried formed activated carbon in the first solution, and stir and mix at room temperature for 0.5 h; then let it stand and soak for 24 h; put the obtained mixture into a 600 W microwave oven and heat it at 70 °C for 0.5 h.

[0107] After microwave heating, use a rotary evaporator to perform rotary evaporation and drying at 60 °C for 0.5 h to make the activated carbon appear dry. Place the obtained roughly dried activated carbon sample in a vacuum drying oven at 120 °C for 4 h of deep drying to prepare the hydrophobic activated carbon and store it in a desiccator.

[0108] Example 10

[0109] Carry out the implementation according to the method described in Example 6, the difference is that the microwave heating step is removed.

[0110] Specifically as follows:

[0111] Weigh 10 g of the formed activated carbon and heat it in an oven at 120 °C for 12 h of drying; weigh 0.2 g of the short-chain polymer (polystyrene M WWeigh 2 g of short-chain polymer (polystyrene M

[0112] 4000), dissolve it in 100 ml of ethanol, and stir evenly to obtain the first solution (that is, the weight ratio of the short-chain polymer to the amount of formed activated carbon is 1:50); immerse the dried formed activated carbon in the first solution, and stir and mix at room temperature for 0.5 h; then ultrasonically oscillate at a power of 40 Hz for 2 h, and then let it stand and soak for 24 h.

[0113] Comparative Example 1

[0114] Carry out the implementation according to the method described in Example 6. The difference is that the formed activated carbon is replaced by powdered activated carbon, and extrusion granulation is carried out after the modification treatment to obtain columnar particulate hydrophobic activated carbon (the specific surface area of this hydrophobic activated carbon is 1015 m 2 / g, the particle diameter is 3 mm, and the length is 5 mm).

[0115] Specifically as follows:

[0116] Weigh 10 g of powdered activated carbon (specific surface area 1375 m 2 / g, the particle size is 0.01 - 0.1 mm), place it in an oven at 120 °C and heat and dry for 12 h; weigh 0.2 g of short-chain polymer (polystyrene M W 4000), dissolve it in 100 ml of ethanol, and stir evenly to obtain the first solution (that is, the weight ratio of the short-chain polymer to the amount of powdered activated carbon is 1:50); immerse the dried powdered activated carbon in the first solution, and stir and mix at room temperature for 0.5 h; then ultrasonically oscillate at a power of 40 Hz for 2 h, and then let it stand and soak for 24 h; put the obtained mixture into a 600 W microwave oven and heat at 70 °C for 0.5 h. After microwave heating, use a rotary evaporator to carry out rotary evaporation and drying at 60 °C for 0.5 h to make the activated carbon appear dry, and place the obtained roughly dried activated carbon sample in a vacuum drying oven at 120 °C for deep drying for 4 h to obtain hydrophobic activated carbon powder.

[0117] Mix the hydrophobic activated carbon powder and methyl cellulose evenly according to a mass ratio of 95:5, add a mixed solvent of water and ethanol, knead it into a dough, and put it into a twin-screw extruder for extrusion granulation to obtain columnar particulate hydrophobic activated carbon.

[0118] Comparative Example 2

[0119] Carry out the implementation according to the method described in Example 6. The difference is that the short-chain polymer (polystyrene M W 4000) is replaced by perfluoro-1-octanol.​​​​​

[0120] Comparative Example 3

[0121] The method described in Example 6 was implemented, except that rotary evaporation drying was replaced by suction filtration separation.

[0122] Specifically as follows:

[0123] Weigh 10 g of formed activated carbon and heat it in an oven at 120 °C for 12 h; weigh 0.2 g of short-chain polymer (polystyrene M W 4000), dissolve it in 100 ml of ethanol, stir evenly to obtain the first solution (that is, the weight ratio of the short-chain polymer to the formed activated carbon is 1:50); immerse the dried formed activated carbon in the first solution and stir and mix at room temperature for 0.5 h; then ultrasonically oscillate at a power of 40 Hz for 2 h, and then let it stand and soak for 24 h; put the obtained mixture into a 600 W microwave oven and heat it at 70 °C for 0.5 h.

[0124] After microwave heating, suction filtration separation was carried out using a pump until the activated carbon was apparently dry. The obtained roughly dried activated carbon sample was placed in a vacuum drying oven at 120 °C for deep drying for 4 h to prepare hydrophobic activated carbon and stored in a desiccator.

[0125] Comparative Example 4

[0126] The method described in Example 6 was implemented, except that polystyrene M W 4000 was replaced with polystyrene M W 500.

[0127] Test Example 1

[0128] The unmodified formed activated carbon was analyzed and detected using a physical adsorption analyzer, and its N2 adsorption-desorption isotherm is as Figure 1 shown.

[0129] It can be seen from Figure 1 that the adsorption shows a type I adsorption isotherm, indicating that the formed activated carbon is a microporous material.

[0130] Test Example 2

[0131] The specific surface area, water contact angle, and adsorption performance of the hydrophobic modified activated carbon prepared in the examples and comparative examples, as well as the unmodified formed activated carbon and powdered activated carbon, were tested. The test results and some conditions in each example are shown in Table 1 below. In Table 1, the modifier refers to formed activated carbon, powdered activated carbon, or perfluoro-1-octanol.

[0132] Table 1

[0133]

[0134]

[0135]

[0136] As can be seen from the results in Table 1, the hydrophobic activated carbons prepared in Examples 1-10 have excellent hydrophobic properties, with a small water adsorption amount and a high adsorption amount of light hydrocarbons (propane). This shows that the preparation method provided by the present invention, through the design of raw materials and preparation steps, enables the prepared hydrophobic activated carbon to have excellent adsorption performance for VOCs in high-humidity crude oil volatile gas.

[0137] As can be seen from Example 3 and Examples 6-7, when using three polymers, namely polyethyleneimine (MW 1800), polystyrene (MW4000), and polystyrene (MW 50000), to hydrophobically modify the shaped activated carbon, the prepared hydrophobic activated carbon has good hydrophobic properties. And as the polymer molecular weight / molecular size increases, the specific surface area of the obtained hydrophobic activated carbon decreases and the hydrophobic property deteriorates. This may be because the smaller the polymer molecular size, the more uniformly and dispersedly it is coated on the surface of the shaped activated carbon without holes.

[0138] As can be seen from Example 6 and Comparative Example 1, compared with powdered activated carbon, the hydrophobic activated carbon prepared with shaped activated carbon as the raw material has better hydrophobic properties. This may be because after the powdered activated carbon is hydrophobically modified, it needs to be granulated again. When the hydrophobically modified powdered activated carbon is granulated again, part of the polymer molecules are distributed inside the granular activated carbon, and most of the external area of the material still has hydrophilicity. Therefore, there is still competitive adsorption of water vapor, and the hydrophobic modification effect is not as good as directly hydrophobically modifying the shaped activated carbon.

[0139] As can be seen from Example 6 and Comparative Example 2, when replacing the short-chain polymer with perfluorooctanol, which is commonly used for hydrophobically modifying activated carbon, the specific surface area of the prepared hydrophobically modified activated carbon is greatly reduced. This may be because the molecular weight of perfluorooctanol is very small and it is easy to enter the pores of the shaped activated carbon and block the pores. At the same time, the adsorption amount of propane of the hydrophobic activated carbon prepared by using perfluorooctanol for modification decreases significantly. This may be due to the hydrophobic and lipophobic properties of perfluorooctanol. Although the hydrophobicity of the shaped activated carbon is improved after modification, its adsorption property for propane also decreases.

[0140] As can be seen from Example 6 and Comparative Example 3, the hydrophobic effect of the hydrophobic activated carbon prepared by rotary evaporation to dry the solvent is better than that prepared by conventional suction filtration for solid-liquid separation. This may be because suction filtration for solid-liquid separation will cause the loss of the hydrophobic modifier with the filtration of the solvent, reducing the proportion of the modifier on the surface of the shaped activated carbon and lowering the hydrophobic modification effect.

[0141] It can be seen from Example 6 and Comparative Example 4 that when the polymer is polystyrene (MW 500), although the prepared hydrophobic activated carbon has good hydrophobic properties, the adsorption amount of propane decreases. This may be because when the size of the polymer is too small (lower than the pore size of the activated carbon), it will cause partial blockage of the pores of the activated carbon, resulting in a decrease in the specific surface area and light hydrocarbon adsorption amount of the hydrophobic activated carbon material.

[0142] 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 method for preparing hydrophobic activated carbon, characterized in that, The method includes: drying the formed activated carbon, then mixing it with a short-chain polymer and an organic solvent, and then performing rotary evaporation drying and vacuum drying; Among them, the weight-average molecular weight of the short-chain polymer is 1000-50000; The short-chain polymer is selected from one or more of butyl acrylate, polyvinyl acetate, polylactic acid, polysiloxane, polyethylene, polypropylene, polyisobutylene, polystyrene, poly(4-tert-butylstyrene), polybutadiene, polyvinyl ethyl ether, polyvinyl formal, poly(ethylene carbonate), epichlorohydrin polymer, polyethyleneimine, polyetherimide, poly(methyl isopropyl ether), and polyglycolide.

2. The method according to claim 1, characterized in that, The formed activated carbon is columnar particles with a diameter of 2-6 mm and a length of 2-7 mm; Preferably, the specific surface area of the formed activated carbon is 1200-1300 m 2 / g, and the average pore diameter is 0.5-5 nm.

3. The method according to claim 1, wherein The size of the short-chain polymer is larger than the pore diameter of the formed activated carbon.

4. The method according to any one of claims 1-3, characterized in that, The weight-average molecular weight of the short-chain polymer is 1000-10000.

5. The method according to claim 1, wherein The weight ratio of the dosage of the short-chain polymer to the formed activated carbon is 1:10-200, preferably 1:40-100; Preferably, the dosage ratio of the formed activated carbon to the organic solvent is 5-20 g:100 mL.

6. The method according to claim 1, characterized in that, The organic solvent is selected from one or more of methanol, ethanol, propanol, dichloromethane, and chloroform.

7. The method according to claim 1, characterized in that, When drying the formed activated carbon, the drying conditions include: a temperature of 80-150 °C and a time of 2-15 h.

8. The method according to claim 1, wherein The specific process of the mixing includes: (1) Mix the short-chain polymer and the organic solvent to obtain a first solution; (2) Immerse the dried formed activated carbon in the first solution, stir and mix, ultrasonically oscillate, soak statically, and then heat by microwave.

9. The method according to claim 8, wherein In step (2), the stirring and mixing time is 0.5-2 h; Preferably, in step (2), the ultrasonic oscillation conditions include: a frequency of 40-100 KHz and a time of 0.5-5 h; Preferably, in step (2), the static soaking time is 1-24 h; Preferably, in step (2), the microwave heating conditions include: a power of 500-800 W, a temperature of 40-70 °C, and a time of 0.5-2 h.

10. The method according to claim 1, wherein The temperature of the rotary evaporation drying is 30-60 °C and the time is 0.2-2 h; Preferably, the temperature of the vacuum drying is 60-120 °C and the time is 4-24 h.

11. Hydrophobic activated carbon prepared by the method according to any one of claims 1-10.

12. The hydrophobic activated carbon according to claim 11, wherein, The specific surface area of the hydrophobic activated carbon is 800 to 1210 m 2 / g, and the surface contact angle with water is greater than 100°.

13. Use of the hydrophobic activated carbon according to claim 11 or 12 in adsorbing VOCs in the volatile gas of crude oil.

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