Process for removing petroleum acids by electric field coupled continuous solid phase extraction

Abstract

The application provides a process method for removing petroleum acid by electric field coupling continuous solid phase extraction, and belongs to the technical field of petroleum refining and processing. The process comprises the following steps: arranging two parallel separators which alternately work between an electric desalting device and an atmospheric-vacuum distillation device, arranging fillers and an electric field in the separators, when the device is in deacidification operation, naphthenic acid in crude oil is adsorbed by the fillers through the electric field to realize efficient separation, when the device is in backwashing operation, the naphthenic acid adsorbed by the fillers is extracted by backwashing solvent and is sent to a solvent recovery process, and the separation and backwashing processes are automatically switched and cyclically performed. The application uses the continuous solid phase extraction technology to remove the naphthenic acid in the crude oil, avoids the change of the properties of the crude oil caused by chemical reaction, strengthens the polarity of the fillers through the electric separation technology, promotes the movement of the naphthenic acid to the active adsorption sites on the fillers, and improves the deacidification rate and the deacidification depth.

Description

TECHNICAL FIELD

[0001] The present application relates to a process for removing naphthenic acids by electric field coupling continuous solid phase extraction, and belongs to the technical field of petroleum refining. BACKGROUND

[0002] At present, the methods for removing naphthenic acids mainly consider two aspects: physical separation and chemical conversion. One is to destructively remove the carboxyl groups in naphthenic acids, and the other is to separate and recycle the naphthenic acids as a whole. The process routes for destructively removing the carboxyl groups in naphthenic acids mainly include catalytic hydrogenation deacidification, catalytic cracking deacidification, and catalytic reaction deacidification. The process routes for separating and recycling naphthenic acids mainly include chemical reaction separation, adsorption separation, solvent extraction separation, and membrane separation. Among these methods, the adsorption separation technology has many advantages for removing naphthenic acids from crude oil, such as avoiding the generation of a large amount of waste water and waste, and simple process flow. However, the traditional adsorbents, such as bauxite, zeolite, silica gel, and activated clay, have poor deacidification effect.

[0003] In recent years, ionic liquids have become the darling of research on removing naphthenic acids from crude oil due to their unique physical and chemical properties. In the prior art, Li Jing et al. introduced in the document "Research on removing naphthenic acids from acidic oil products by ionic liquids" that a series of ionic liquids were synthesized by a two-step method, which were applied to remove naphthenic acids from oil products, and the effects of ionic liquids with different structures and different process conditions on deacidification were investigated. It was found that without adding metal chlorides, the deacidification performance gradually increased with the gradual increase of the alkyl chain length on the imidazole ring of the cation of the ionic liquid. MY175248A dissolves tetraalkylammonium hydroxide, tetraalkylphosphonium hydroxide, or choline hydroxide in deionized water to form an ionic liquid, and mixes the ionic liquid with crude oil to remove naphthenic acids from the crude oil, and then separates the liquid-liquid two phases. However, the use of ionic liquids for deacidification requires an additional separation process, making the operation cumbersome, increasing equipment investment, and easily introducing impurities into the oil product. The introduction of ionic liquids into polymers can obtain ionic liquid polymers (PILs). PILs are a class of polymers that contain at least one ionic center in the polymer chain, and have similar structures to common ionic liquids. Such polymers have excellent properties of both ionic liquids and high polymers. Therefore, ionic liquid polymers are a potential adsorbent for removing naphthenic acids from crude oil, but there is no related research report in the field of naphthenic acid removal.

[0004] In addition, in the field of adsorption separation research, electric separation technology can effectively enhance the adsorption process. Electric separation technology is based on nonlinear electric field theory, uses electrophoresis and dielectrophoresis principles, and optimizes electromagnetic field gradient to enhance adsorption of heteroatom polar compounds including naphthenic acid. At present, electric separation technology is widely used in catalytic cracking slurry desolidification. In the prior art, CN112592736A uses high gradient electric field separation technology to enhance the adsorption process of the filler to the solid in the catalytic oil slurry, so that the solid content of the treated oil slurry is less than 50 ppm. In CN108359491A, a high-voltage electrostatic separation device forms a non-uniformly distributed electric field between the central copper electrode and the shell, and the spoiler makes the internal flow field distribution uneven, which is conducive to the adsorption of particles and improves the separation efficiency. The effect of desolidification is good; no filler is used inside to avoid the occurrence of plugging phenomenon, backwashing is more rapid, time is saved. However, there is no related report on the application of electric separation technology in the field of crude oil deacidification. SUMMARY

[0005] The purpose of the present application is to provide a process for removing petroleum acid by electric field coupling continuous solid phase extraction, which uses solidified imidazole ionic liquid polymer material to adsorb naphthenic acid in oil products, and combines electric separation technology to enhance the adsorption process.

[0006] In order to achieve the above purpose, the present application provides the following technical scheme:

[0007] A process for removing petroleum acid by electric field coupling continuous solid phase extraction, the method comprising:

[0008] Two parallel working separators are arranged between the electric desalting device and the atmospheric and vacuum distillation device, and the deacidification operation and backwashing operation are carried out through the separators to realize the continuous deacidification process. The separators are the same structure, which is a vertical fixed bed adsorption device with additional electric field. The device is provided with a filler bed, and an electrode plate is arranged in the filler bed to provide a static electric field;

[0009] When the deacidification operation is carried out, the crude oil is introduced into the filler bed in the middle section of the reactor through the feed nozzle at the upper part of the separator after being dehydrated and desalted by the electric desalting device. The filler bed is provided with fillers, which are adsorbed by the fillers through the electric field. When separating, the crude oil passes through the device from top to bottom and leaves from the discharge port at the bottom of the separator to the crude oil buffer tank. When the fillers approach saturation adsorption, the device stops the deacidification operation and starts the backwashing operation, and the other parallel separator starts the deacidification operation. When backwashing is carried out, the flow of crude oil into the device is stopped, the solvent pipeline is switched, and the naphthenic acid adsorbed by the fillers is extracted by the backwashing solvent. The mixed liquid is sent to the solvent recovery process.

[0010] Preferably, the temperature of the crude oil after being dehydrated and desalted by the electric desalting device is 80-155℃, and the space velocity LHSV of the separator is 1000-5000h－1 .

[0011] Preferably, the electric field strength applied to the electrode plate is 0.1-5V.

[0012] Preferably, the backwashing solvent is one of methanol, ethanol, isopropanol, acetonitrile, acetone, tetrahydrofuran, n-butanol, ethyl acetate, diethyl ether, isopropyl ether, dichloromethane, chloroform, and bromoethane.

[0013] Preferably, the filler is an imidazole-based ionic liquid polymer.

[0014] Preferably, the method for preparing an imidazole-based ionic liquid polymer includes:

[0015] Step 1: React alkenyl imidazole with haloalkylamines or haloalkanes in a solvent to generate imidazole ionic liquids;

[0016] Step 2: Under the influence of a free radical initiator, the imidazole ionic liquid from Step 1 undergoes a free radical polymerization reaction with the comonomer to generate an imidazole ionic liquid polymer.

[0017] Preferably, the alkenylimidazole in step one is 1-vinylimidazole, 2-vinylimidazole, 2-methyl-1-vinylimidazole, N-allylimidazole, 2-styryl-1H-imidazole or 2-vinyl-(9ci)-1H-benzimidazole.

[0018] Preferably, the alkyl halogenated amine in step one is 3-chloropropylamine, 4-chlorobutylamine, 4-bromo-1-butylamine, or 5-bromopentamine; and the alkyl halogenated hydrocarbon is 1-bromooctane, 1-chlorodecane, 1-bromododecane, or 1-bromohexadecane.

[0019] Preferably, the comonomer in step two is styrene, divinylbenzene, vinylpyridine, or vinylnaphthalene.

[0020] Preferably, the free radical initiator in step two is azobisisobutyronitrile, azobisisoheptanenitrile, cumene hydroperoxide, tert-butyl hydroperoxide, benzoyl peroxide, cyclohexanone peroxide, di-tert-butyl peroxide, or dicumene peroxide.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention uses continuous solid phase extraction technology to remove naphthenic acids from crude oil, thus avoiding chemical reactions that could alter the properties of crude oil.

[0023] (2) The present invention enhances the polarity of the packing through electro-separation technology, promotes the movement of naphthenic acid to the active adsorption sites on the packing, and improves the deacidification rate and deacidification depth. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0025] Figure 1 This is a schematic diagram of the separator of the present invention.

[0026] Figure 2 The graph shows the changes in deacidification rate over time under different process conditions in Comparative Examples 1-2 and Examples 2-4. Detailed Implementation

[0027] A process for removing petroleum acid by continuous solid-phase extraction coupled with electric field coupling, the method comprising:

[0028] Two separators are installed side-by-side between the electrostatic desalination unit and the atmospheric and vacuum distillation unit, operating alternately. These separators perform deacidification and backwashing operations. The separators have identical structures. Figure 1 As shown, the separator is a vertical fixed-bed adsorption device with an additional electric field. The middle section of the device is equipped with a packing bed, and electrode plates are installed in the packing bed to provide an electrostatic field.

[0029] During the deacidification process, crude oil is dehydrated and desalted by the electrostatic desalting unit and then enters the packed bed in the middle section of the reactor through the feed nozzle at the top of the separator. The packed bed is filled with packing material. The oil slurry passes through the electric field in the electrode plate, causing the naphthenic acid in the crude oil to be adsorbed by the packing material. During separation, the crude oil passes through the device from top to bottom and leaves from the discharge port at the bottom of the separator to the crude oil buffer tank. When the packing material is close to saturation adsorption, the device stops the deacidification operation and starts the backwashing operation. Meanwhile, another separator in parallel starts the deacidification operation. During the backwashing operation, the crude oil supply to the device is stopped, the electrode plate is de-energized, the electric field disappears, and the process switches to the solvent pipeline. The backwashing solvent is introduced to extract the naphthenic acid adsorbed by the packing material, and the mixture is sent to the solvent recovery process.

[0030] According to the present invention, the temperature of the crude oil after dehydration and desalting by the electrostatic desalting device is preferably 80-155°C, and the space velocity (LHSV) after passing through the separator is preferably 1000-5000 h⁻¹. －1 .

[0031] According to the present invention, the electric field strength applied to the electrode plate is preferably 0.1-5V.

[0032] According to the present invention, the backwashing solvent is preferably one of methanol, ethanol, isopropanol, acetonitrile, acetone, tetrahydrofuran, n-butanol, ethyl acetate, diethyl ether, isopropyl ether, dichloromethane, chloroform, and bromoethane.

[0033] According to the present invention, the filler is preferably an imidazole-based ionic liquid polymer, and the preparation method preferably includes:

[0034] Step 1: React alkenyl imidazole with haloalkylamine or haloalkane in a solvent, and after purification, generate an imidazole ionic liquid; the reaction temperature is preferably 20-100℃, more preferably 60℃, and the reaction time is preferably 1-48h, more preferably 24h; the molar ratio of alkenyl imidazole to haloalkylamine or haloalkane is preferably (0.01-100):1, more preferably 1:1.

[0035] The alkenylimidazole is preferably 1-vinylimidazole, 2-vinylimidazole, 2-methyl-1-vinylimidazole, N-allylimidazole, 2-styryl-1H-imidazole, 2-vinyl-(9ci)-1H-benzimidazole, and more preferably 1-vinylimidazole.

[0036] The alkyl halogenated amine is preferably 3-chloropropylamine, 4-chlorobutylamine, 4-bromo-1-butylamine or 5-bromopentamine, more preferably 4-chlorobutylamine; the alkyl halogenated hydrocarbon is preferably 1-bromooctane, 1-chlorodecane, 1-bromododecane or 1-bromohexadecane, more preferably 1-bromododecane.

[0037] The solvent is preferably methanol, ethanol, isopropanol, dichloromethane, chloroform, tetrahydrofuran, benzene, toluene, xylene, N,N-dimethylformamide, N,N-dimethyl sulfoxide, and more preferably isopropanol.

[0038] Step 2: Under the influence of a free radical initiator, the imidazole ionic liquid from Step 1 undergoes a free radical polymerization reaction with the comonomer, and after purification, an imidazole ionic liquid polymer is generated; the preferred temperature of the free radical polymerization reaction is 20-100℃, more preferably 60℃, and the preferred reaction time is 1-48h, more preferably 24h.

[0039] The preferred molar ratio of alkenylimidazolium to comonomer is (0.01-100):1, and the preferred molar ratio of alkenylimidazolium to free radical initiator is (0.01-100):1.

[0040] The comonomer is preferably styrene, divinylbenzene, vinylpyridine, or vinylnaphthalene, and more preferably styrene.

[0041] The free radical initiator is preferably azobisisobutyronitrile, azobisisoheptanenitrile, cumene hydroperoxide, tert-butyl hydroperoxide, benzoyl peroxide, cyclohexanone peroxide, di-tert-butyl peroxide, or dicumene peroxide, and more preferably azobisisobutyronitrile.

[0042] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0043] The present invention will be further described below with reference to the embodiments.

[0044] Example 1

[0045] Specific preparation methods for imidazole ionic liquid polymers (PILs):

[0046] 4-Chlorobutylamine and 1-vinylimidazole were added to a flask in a molar ratio of 1:1, and the mixture was reacted at 60°C for 24 h using isopropanol as the solvent. After the reaction was completed, the isopropanol was removed by rotary evaporation, and the product was washed several times with anhydrous diethyl ether. Then, the diethyl ether was removed by rotary evaporation to obtain a yellow viscous liquid, which was the ionic liquid of 1-(4-amino)butyl-3-vinylimidazole chloride.

[0047] N,N-dimethylformamide was purified by adding anhydrous magnesium sulfate, stirring overnight with a magnetic stirrer, and then distilling under reduced pressure to obtain purified N,N-dimethylformamide.

[0048] The prepared 1-(4-amino)butyl-3-vinylimidazolium chloride ionic liquid was mixed with vinylpyridine at a molar ratio of 1:1. Azobisisobutyronitrile was added using N,N-dimethylformamide as a solvent, and N2 was bubbled in for 20 min. The reaction was carried out at 60 °C for 24 h. After the reaction was completed, the reaction mixture was poured into ethyl acetate, and a white solid precipitate immediately formed. The solid was separated by centrifugation, washed several times with ethyl acetate, and dried under vacuum at 45 °C for 12 h to obtain purified polyionic liquids (PILs).

[0049] Comparative Example 1

[0050] The separator uses ordinary glass packing. The feed pump is started, and crude oil is drawn from the feed tank into the separator for deacidification. The pump flow rate is adjusted so that the crude oil's space velocity (LHSV) through the separator's packing section is 1000 h⁻¹. －1 Then, the heating furnace power was adjusted to heat the Shengli crude oil to the separator inlet temperature of 130℃, and the electrostatic field strength was adjusted to 0.1V. Samples were taken and the acid value was measured at 30min, 1h, 2h, 4h, 6h, and 8h of equipment operation. Then, heating was stopped, the pump was stopped, and the electrostatic field was turned off. The backwash solvent pump was started to wash off the naphthenic acid adsorbed on the packing material, which was carried away with the solvent into the solvent recovery tank.

[0051] Comparative Example 2

[0052] Replace the packing material in the separator with the imidazole ionic liquid polymer prepared in Example 1. Start the feed pump, and draw crude oil from the feed tank into the separator for deacidification. Adjust the pump flow rate so that the space velocity (LHSV) of the crude oil passing through the packing section of the separator is 1000 h⁻¹. －1 Then, the heating furnace power is adjusted to heat the Shengli crude oil to the separator inlet temperature of 130℃. Without applying an electrostatic field, samples are taken and the acid value is measured at 30 min, 1 h, 2 h, 4 h, 6 h, and 8 h of equipment operation. Then, heating and pumps are stopped. The backwash solvent pump is started to wash off the naphthenic acid adsorbed on the packing material, which is carried away with the solvent into the solvent recovery tank.

[0053] Example 2

[0054] Replace the packing material in the separator with the imidazole-based ionic liquid polymers (PILs) prepared in Example 1. Start the feed pump, and draw crude oil from the feed tank into the separator for deacidification. Adjust the pump flow rate so that the crude oil space velocity (LHSV) through the packing section of the separator is 1000 h⁻¹. －1 Then, the heating furnace power was adjusted to heat the Shengli crude oil to the separator inlet temperature of 130℃, and the electrostatic field strength was adjusted to 0.1V. Samples were taken and the acid value measured at 30min, 1h, 2h, 4h, 6h, and 8h of equipment operation. Heating was then stopped, the pump was stopped, and the electrostatic field was shut off. The backwash solvent pump was started to flush down the naphthenic acid adsorbed on the packing material, which was carried away with the solvent into the solvent recovery tank. The above operation was repeated twice.

[0055] Example 3

[0056] Replace the packing material in the separator with the imidazole-based ionic liquid polymers (PILs) prepared in Example 1. Start the feed pump, and draw crude oil from the feed tank into the separator for deacidification. Adjust the pump flow rate so that the crude oil space velocity (LHSV) through the packing section of the separator is 4000 h⁻¹. －1 Then, the heating furnace power was adjusted to heat the Shengli crude oil to the separator inlet temperature of 100℃, and the electrostatic field strength was adjusted to 0.1V. Samples were taken and the acid value measured at 30min, 1h, 2h, 4h, 6h, and 8h of equipment operation. Heating was then stopped, the pump was stopped, and the electrostatic field was turned off. The backwash solvent pump was started to flush down the naphthenic acid adsorbed on the packing material, which was carried away with the solvent into the solvent recovery tank. The above operation was repeated twice.

[0057] Example 4

[0058] Replace the packing material in the separator with the imidazole-based ionic liquid polymers (PILs) prepared in Example 1. Start the feed pump, and draw crude oil from the feed tank into the separator for deacidification. Adjust the pump flow rate so that the crude oil space velocity (LHSV) through the packing section of the separator is 1000 h⁻¹. －1Then, the heating furnace power was adjusted to heat the Shengli crude oil to the separator inlet temperature of 100℃, and the electrostatic field strength was adjusted to 0.4V. Samples were taken and the acid value was measured at 30min, 1h, 2h, 4h, 6h, and 8h of equipment operation. Heating was then stopped, the pump was stopped, and the electrostatic field was turned off. The backwash solvent pump was started to flush down the naphthenic acid adsorbed on the packing material, which was carried away with the solvent into the solvent recovery tank. The above operation was repeated twice.

[0059] Figure 2 The graphs show a comparison of the deacidification rate over time under different process conditions in Examples 1-2 and Examples 2-4. As can be seen from the graphs, compared to ordinary glass packing, imidazole-based ionic liquid polymers have a stronger adsorption effect on naphthenic acids, and the use of electric field coupling can effectively promote the improvement of the deacidification effect. Furthermore, data from multiple cycles show that the device has good deacidification repeatability and can operate stably for a long period.

[0060] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A process for removing petroleum acid by continuous solid-phase extraction coupled with electric field coupling, characterized in that, The method includes: Two separators are set up in parallel between the electrostatic desalination unit and the atmospheric and vacuum distillation unit, which work alternately. The separators are used for deacidification and backwashing to achieve a continuous deacidification process. The two separators have the same structure. The separator is a vertical fixed bed adsorption device with an additional electric field. The device is equipped with a packing bed, and electrode plates are set in the packing bed to provide an electrostatic field. During the deacidification process, crude oil is dehydrated and desalted by the electrostatic desalting unit and then enters the packed bed in the middle section of the reactor through the feed nozzle at the top of the separator. The packed bed is filled with packing material, which is adsorbed by the packing material through the electric field. During separation, the crude oil passes through the device from top to bottom and leaves from the discharge port at the bottom of the separator to the crude oil buffer tank. When the packing material is close to saturated adsorption, the device stops the deacidification operation and starts the backwashing operation. Meanwhile, another separator in parallel starts the deacidification operation. During the backwashing operation, the crude oil is stopped from being fed into the device, and the process is switched to the solvent pipeline. The backwashing solvent is introduced to extract the naphthenic acid adsorbed by the packing material, and the mixture is sent to the solvent recovery process. The filler is an imidazole-based ionic liquid polymer, and the preparation method of the imidazole-based ionic liquid polymer includes: Step 1: React alkenyl imidazole with haloalkylamines or haloalkanes in a solvent to generate imidazole ionic liquids; Step 2: Under the influence of a free radical initiator, the imidazole ionic liquid from Step 1 undergoes a free radical polymerization reaction with the comonomer to generate an imidazole ionic liquid polymer.

2. The process for removing petroleum acid by continuous solid-phase extraction with electric field coupling according to claim 1, characterized in that, The crude oil temperature after dehydration and desalting by the electrostatic desalting unit is 80-155 ℃, and the space velocity (LHSV) after passing through the separator is 1000-5000 h⁻¹. -1 .

3. The process for removing petroleum acid by continuous solid-phase extraction with electric field coupling according to claim 1, characterized in that, The electric field strength applied to the electrode plate is 0.1-5 V.

4. The process for removing petroleum acid by continuous solid-phase extraction with electric field coupling according to claim 1, characterized in that, The backwashing solvent is one of methanol, ethanol, isopropanol, acetonitrile, acetone, tetrahydrofuran, n-butanol, ethyl acetate, diethyl ether, isopropyl ether, dichloromethane, chloroform, and bromoethane.

5. The process for removing petroleum acid by continuous solid-phase extraction with electric field coupling according to claim 1, characterized in that, The alkenyl imidazole mentioned in step one is 1-vinylimidazolium, 2-vinylimidazolium, 2-methyl-1-vinylimidazolium, N-allylimidazolium, 2-styryl-1H-imidazolium or 2-vinyl-(9ci)-1H-benzimidazole.

6. The process for removing petroleum acid by continuous solid-phase extraction with electric field coupling according to claim 1, characterized in that, The alkyl halogenated amine mentioned in step one is 3-chloropropylamine, 4-chlorobutylamine, 4-bromo-1-butylamine, or 5-bromopentamine; the alkyl halogenated hydrocarbon is 1-bromooctane, 1-chlorodecane, 1-bromododecane, or 1-bromohexadecane.

7. The process for removing petroleum acid by continuous solid-phase extraction with electric field coupling according to claim 1, characterized in that, The comonomers mentioned in step two are styrene, divinylbenzene, vinylpyridine, or vinylnaphthalene.

8. The process for removing petroleum acid by continuous solid-phase extraction with electric field coupling according to claim 1, characterized in that, The free radical initiator mentioned in step two is azobisisobutyronitrile, azobisisoheptanenitrile, cumene hydroperoxide, tert-butyl hydroperoxide, benzoyl peroxide, cyclohexanone peroxide, di-tert-butyl peroxide, or dicumene peroxide.

Images