Process method for removing petroleum acid through electric field coupling continuous solid-phase extraction

Abstract

The invention provides a technological method for removing petroleum acid through electric field coupling continuous solid-phase extraction, and belongs to the technical field of petroleum refining processing. According to the process, two alternately working separators are arranged in parallel between an electric desalting device and an atmospheric and vacuum distillation device, fillers and electric fields are arranged in the separators, when the devices are in deacidification operation, naphthenic acid in crude oil is adsorbed by the fillers through the electric fields to realize efficient separation, and when the devices are in backwashing operation, the naphthenic acid in the crude oil is separated by the fillers through the electric fields. The naphthenic acid adsorbed by the filler is extracted by the backwashing solvent and sent to the solvent recovery process, and the separation process and the backwashing process are automatically switched and cyclically carried out. According to the method, the naphthenic acid in the crude oil is removed by using a continuous solid-phase extraction technology, the change of the property of the crude oil caused by chemical reaction is avoided, the polarity of the filler is enhanced by using an electric separation technology, the naphthenic acid is promoted to move towards an active adsorption site on the filler, and the deacidification rate and the deacidification depth are improved.

Description

Technical Field

[0001] The invention relates to a process for removing petroleum acid by electric field coupled continuous solid phase extraction, belonging to the technical field of petroleum refining and processing. Background Art

[0002] At present, the methods for removing cyclohexane acid are mainly considered from two aspects: physical separation and chemical conversion: one is to destructively remove the carboxyl group in cyclohexane acid; the other is to separate and recover the cyclohexane acid as a whole and make use of it. The process routes for destructively removing the carboxyl group from the cyclohexane acid molecule mainly include catalytic hydrogenation deacidification, catalytic cracking deacidification, catalytic reaction deacidification, etc.; the process routes for separating and recycling cyclohexane acid mainly include chemical reaction separation, adsorption separation, solvent extraction separation and membrane separation. Among these methods, adsorption separation technology has many advantages for crude oil deacidification, avoiding the generation of a large amount of wastewater and waste, and the process flow is simple, but the deacidification effect of traditional adsorbents such as bauxite, zeolite, silica gel, activated clay, etc. is poor.

[0003] In recent years, ionic liquids have become the darling of crude oil deacidification research due to their unique physical and chemical properties. In the prior art, Li Jing et al. introduced in the document "Research on the Removal of Cyclohexane Acids from Acidic Oils by Ionic Liquids" that a series of ionic liquids were synthesized by a two-step method, applied to the removal of cyclohexane acids from oil products, and investigated the effects of ionic liquids with different structures and different process conditions on the deacidification effect. The study found that without the addition of metal chloride, as the alkyl chain length on the cation imidazole ring of the ionic liquid gradually increased, its deacidification performance also gradually improved. MY175248A dissolves tetraalkylammonium hydroxide, tetraalkylphosphonium hydroxide or choline hydroxide in deionized water to form an ionic liquid, and mixes it with crude oil to remove cyclohexane acids from the crude oil, and then separates the liquid-liquid two phases. However, the use of ionic liquids for deacidification requires the addition of additional separation steps, making the operation cumbersome, increasing equipment investment, and easily introducing impurities into the oil products. Ionic liquid polymers (PILs) can be obtained by introducing ionic liquids into polymers. PILs are a type of polymer that contains at least one ionic center in the polymer chain and has a similar structure to common ionic liquids. These polymers have the excellent properties of both ionic liquids and polymers. Therefore, ionic liquid polymers are highly potential adsorbents in the field of crude oil deacidification, but there have been no related research reports in the field of petroleum acid removal.

[0004] In addition, in the field of adsorption separation research, electrical separation technology can effectively enhance the adsorption process. Electrical separation technology is based on nonlinear electric field theory, using the principles of electrophoresis and dielectrophoresis to optimize the electromagnetic field gradient to enhance the adsorption of heteroatom polar compounds including cyclopentane acid. At present, electrical separation technology is widely used in catalytic cracking oil slurry to remove solids. In the prior art, CN112592736A uses high-gradient electric field separation technology to enhance the adsorption process of fillers on solids in catalytic oil slurry, so that the solid content of the treated oil slurry is less than 50ppm. In CN108359491A, the high-voltage electrostatic separation device forms an unevenly distributed electric field between the central copper electrode and the outer shell, and the spoiler makes the flow field inside it unevenly distributed, which is conducive to the adsorption of particles, improves the separation efficiency, and has a good desolidification effect; no filler is used inside, which avoids the occurrence of clogging, and the backwashing is faster, saving time. However, there are no related reports on the application of electrical separation technology in the field of crude oil deacidification. Summary of the invention

[0005] The purpose of the present invention is to provide a process for removing petroleum acid by electric field coupled continuous solid phase extraction, which uses imidazole ionic liquid polymer materials to solid-phase adsorb cyclohexane acid in oil products and combines electrical separation technology to strengthen the adsorption process.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

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

[0008] Between the electric desalination device and the atmospheric and vacuum decompression device, two separators are arranged in parallel for alternate operation, and deacidification and backwashing operations are performed through the separators to realize a continuous deacidification process. The separators have the same structure and are vertical fixed bed adsorption devices with an additional electric field. A packing bed layer is arranged in the device, and an electrode plate is arranged in the packing bed layer to provide an electrostatic field.

[0009] During the deacidification operation, the crude oil is dehydrated and desalted by the electric desalter and then enters the packing bed in the middle section of the reactor through the feed nozzle at the top of the separator. The packing bed is provided with packing, which is adsorbed by the packing through the electric field. During separation, the crude oil passes through the device from top to bottom and leaves the discharge port at the bottom of the separator to the crude oil buffer tank. When the packing is close to saturated adsorption, the device stops the deacidification operation and starts the backwashing operation, while the other parallel separator starts the deacidification operation. During the backwashing operation, the crude oil is stopped from being introduced into the device, and the solvent pipeline is switched to introduce the backwashing solvent to extract the cyclohexane acid adsorbed by the packing, and the mixed liquid is sent to the solvent recovery process.

[0010] Preferably, the temperature of the crude oil after dehydration and desalting by the electric desalter is 80-155°C, and the LHSV passing through the separator is 1000-5000h－1 .

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

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

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

[0014] Preferably, the method for preparing the imidazole ionic liquid polymer comprises:

[0015] Step 1: reacting alkenyl imidazole with halogenated alkylamine or halogenated hydrocarbon in a solvent to generate an imidazole ionic liquid;

[0016] Step 2: In the presence of a free radical initiator, the imidazole ionic liquid of step 1 is subjected to a free radical polymerization reaction with a comonomer to generate an imidazole ionic liquid polymer.

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

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

[0019] Preferably, the comonomer in step 2 is styrene, divinylbenzene, vinylpyridine or vinylnaphthalene.

[0020] Preferably, the free radical initiator in step 2 is azobisisobutyronitrile, azobisisoheptanenitrile, isopropylbenzene hydroperoxide, tert-butyl hydroperoxide, dibenzoyl peroxide, cyclohexanone peroxide, di-tert-butyl peroxide or diisopropylbenzene 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 cyclohexane acid from crude oil, thereby avoiding chemical reactions that may cause changes in the properties of the crude oil.

[0023] (2) The present invention strengthens the polarity of the filler through the electrical separation technology, promotes the movement of cyclohexane acid to the active adsorption sites on the filler, and improves the deacidification rate and deacidification depth. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

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

[0026] Figure 2 It is a comparison chart of the change of deacidification rate over time under different process conditions of Comparative Examples 1-2 and Examples 2-4. DETAILED DESCRIPTION

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

[0028] Between the electric desalination device and the atmospheric and vacuum decompression device, two separators are arranged in parallel to work alternately, and deacidification and backwashing operations are performed through the separators. The separators have the same structure, such as Figure 1 As shown, the separator is a vertical fixed bed adsorption device with an additional electric field, a packing bed is arranged in the middle section of the device, and an electrode plate is arranged in the packing bed to provide an electrostatic field;

[0029] During the deacidification operation, the crude oil is dehydrated and desalted by the electric desalter and then enters the packing bed in the middle section of the reactor through the feed nozzle at the top of the separator. The packing bed is provided with packing. The oil slurry passes through the electric field in the electrode plate, so that the cyclopentane acid in the crude oil is adsorbed by the packing. During separation, the crude oil passes through the device from top to bottom and leaves the crude oil buffer tank from the discharge port at the bottom of the separator. When the packing is close to saturated adsorption, the device stops the deacidification operation and starts the backwashing operation, while the other parallel separator starts the deacidification operation. During the backwashing operation, the crude oil is stopped from being fed into the device, the electrode plate is powered off, the electric field disappears, and the device is switched to the solvent pipeline. The backwashing solvent is introduced to extract the cyclopentane acid adsorbed by the packing, and the mixed liquid 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 electric desalter is preferably 80-155°C, and the LHSV passing through the separator is preferably 1000-5000h －1 .

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

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

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

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

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

[0036] The halogenated alkylamine is preferably 3-chloropropylamine, 4-chlorobutylamine, 4-bromo-1-butylamine or 5-bromopentylamine, more preferably 4-chlorobutylamine; the 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-dimethylsulfoxide, more preferably isopropanol.

[0038] Step 2: In the presence of a free radical initiator, the imidazole ionic liquid of step 1 is subjected to a free radical polymerization reaction with a comonomer to generate an imidazole ionic liquid polymer after purification; the temperature of the free radical polymerization reaction is preferably 20-100° C., more preferably 60° C., and the reaction time is preferably 1-48 hours, more preferably 24 hours;

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

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

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

[0042] In order 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 in conjunction with the embodiments.

[0044] Example 1

[0045] Specific preparation method of imidazole ionic liquid polymer PILs:

[0046] Add 4-chlorobutylamine and 1-vinylimidazole in a molar ratio of 1:1 into a flask, use isopropanol as solvent, and react at 60°C for 24 hours. After the reaction is completed, the isopropanol is evaporated off, the product is washed with anhydrous ether for several times, and then the ether is evaporated off to obtain a yellow viscous liquid, which is 1-(4-amino)butyl-3-vinylimidazole chloride ionic liquid.

[0047] The N,N-dimethylformamide is purified by adding anhydrous magnesium sulfate, stirring with a magnetic bar overnight, and 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 in a molar ratio of 1:1, N,N-dimethylformamide was used as solvent, azobisisobutyronitrile was added, N2 was bubbled in for 20 minutes, and the reaction was carried out at 60°C for 24 hours. After the reaction was completed, the reaction mixture was poured into ethyl acetate, and a white solid precipitated immediately. The solid was separated by centrifugation, and then the solid was washed with ethyl acetate for many times, and vacuum dried at 45°C for 12 hours to obtain purified polyionic liquids PILs.

[0049] Comparative Example 1

[0050] The filler in the separator uses ordinary glass filler. Start the raw material pump, and the crude oil is pumped from the raw material tank into the separator for deacidification. Adjust the flow of the pump so that the LHSV of the crude oil passing through the separator filler section is 1000h －1 Then adjust the power of the heating furnace to heat Shengli crude oil to 130℃ at the separator inlet, and adjust the electrostatic field strength to 0.1V. Take samples and measure the acid value when the equipment runs for 30min, 1h, 2h, 4h, 6h, and 8h. Then stop heating, stop the pump, and turn off the electrostatic field. Start the backwash solvent pump to wash down the cyclohexane acid adsorbed on the packing and take it away with the solvent into the solvent recovery tank.

[0051] Comparative Example 2

[0052] The filler in the separator was replaced with the imidazole ionic liquid polymer prepared in Example 1. The raw material pump was started, and crude oil was pumped from the raw material tank into the separator for deacidification. The flow rate of the pump was adjusted so that the LHSV of the crude oil passing through the filler section of the separator was 1000 h －1 Then adjust the power of the heating furnace to heat Shengli crude oil to 130℃ at the inlet of the separator. No electrostatic field is added. Samples are taken and the acid value is measured after the equipment is operated for 30min, 1h, 2h, 4h, 6h and 8h. Then stop heating and stop the pump. Start the backwash solvent pump to wash down the cyclohexane acid adsorbed on the packing and take it away with the solvent into the solvent recovery tank.

[0053] Example 2

[0054] The filler in the separator was replaced with the imidazole ionic liquid polymer PILs prepared in Example 1. The raw material pump was started, and crude oil was pumped from the raw material tank into the separator for deacidification. The flow rate of the pump was adjusted so that the LHSV of the crude oil passing through the filler section of the separator was 1000 h －1 Then adjust the power of the heating furnace to heat Shengli crude oil to 130℃ at the inlet oil temperature of the separator, and adjust the electrostatic field strength to 0.1V. Take samples and measure the acid value when the equipment runs for 30min, 1h, 2h, 4h, 6h, and 8h. Then stop heating, stop the pump, and turn off the electrostatic field. Start the backwash solvent pump to wash down the cyclohexane acid adsorbed on the packing and take it away with the solvent into the solvent recovery tank. Repeat the above operation twice.

[0055] Example 3

[0056] The filler in the separator was replaced with the imidazole ionic liquid polymer PILs prepared in Example 1. The raw material pump was started, and crude oil was pumped from the raw material tank into the separator for deacidification. The flow rate of the pump was adjusted so that the LHSV of the crude oil passing through the filler section of the separator was 4000 h －1 Then adjust the power of the heating furnace to heat Shengli crude oil to 100℃ at the inlet oil temperature of the separator, and adjust the electrostatic field strength to 0.1V. Take samples and measure the acid value when the equipment runs for 30min, 1h, 2h, 4h, 6h, and 8h. Then stop heating, stop the pump, and turn off the electrostatic field. Start the backwash solvent pump to wash down the cyclohexane acid adsorbed on the packing and take it away with the solvent into the solvent recovery tank. Repeat the above operation twice.

[0057] Example 4

[0058] The filler in the separator was replaced with the imidazole ionic liquid polymer PILs prepared in Example 1. The raw material pump was started, and crude oil was pumped from the raw material tank into the separator for deacidification. The flow rate of the pump was adjusted so that the LHSV of the crude oil passing through the filler section of the separator was 1000 h －1Then adjust the power of the heating furnace to heat Shengli crude oil to 100℃ at the inlet oil temperature of the separator, and adjust the electrostatic field strength to 0.4V. Take samples and measure the acid value when the equipment runs for 30min, 1h, 2h, 4h, 6h, and 8h. Then stop heating, stop the pump, and turn off the electrostatic field. Start the backwash solvent pump to wash down the cyclohexane acid adsorbed on the packing and take it away with the solvent into the solvent recovery tank. Repeat the above operation twice.

[0059] Figure 2 The comparison chart of the change of deacidification rate over time under different process conditions of Comparative Examples 1-2 and Examples 2-4 shows that, compared with ordinary glass fillers, imidazole ionic liquid polymer has a stronger adsorption effect on cyclohexane acid, and the use of electric field coupling can effectively promote the improvement of deacidification effect. At the same time, after multiple cycles of data, it can be seen that the deacidification device has good repeatability and can operate stably for a long time.

[0060] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that 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 above 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 electric field coupled continuous solid phase extraction, characterized in that: The method includes: Between the electric desalination device and the atmospheric and vacuum decompression device, two separators are arranged in parallel for alternate operation, and deacidification and backwashing operations are performed through the separators to realize a continuous deacidification process. The separators have the same structure and are vertical fixed bed adsorption devices with an additional electric field. A packing bed layer is arranged in the device, and an electrode plate is arranged in the packing bed layer to provide an electrostatic field. During the deacidification operation, the crude oil is dehydrated and desalted by the electric desalter and then enters the packing bed in the middle section of the reactor through the feed nozzle at the top of the separator. The packing bed is provided with packing, which is adsorbed by the packing through the electric field. During separation, the crude oil passes through the device from top to bottom and leaves the discharge port at the bottom of the separator to the crude oil buffer tank. When the packing is close to saturated adsorption, the device stops the deacidification operation and starts the backwashing operation, while the other parallel separator starts the deacidification operation. During the backwashing operation, the crude oil is stopped from being introduced into the device, and the solvent pipeline is switched to introduce the backwashing solvent to extract the cyclohexane acid adsorbed by the packing, and the mixed liquid is sent to the solvent recovery process.

2. The process for removing petroleum acid by electric field coupled continuous solid phase extraction according to claim 1, characterized in that: The temperature of the crude oil after dehydration and desalting by the electric desalting device is 80-155°C, and the LHSV passing through the separator is 1000-5000h －1 .

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

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

5. The process for removing petroleum acid by electric field coupled continuous solid phase extraction according to claim 1, characterized in that: The filler is an imidazole ionic liquid polymer.

6. The process for removing petroleum acid by electric field coupled continuous solid phase extraction according to claim 5, characterized in that: The method for preparing an imidazole ionic liquid polymer comprises: Step 1: reacting alkenyl imidazole with halogenated alkylamine or halogenated hydrocarbon in a solvent to generate an imidazole ionic liquid; Step 2: In the presence of a free radical initiator, the imidazole ionic liquid of step 1 is subjected to a free radical polymerization reaction with a comonomer to generate an imidazole ionic liquid polymer.

7. The process for removing petroleum acid by electric field coupled continuous solid phase extraction according to claim 6, characterized in that: The vinyl imidazole in step 1 is 1-vinylimidazole, 2-vinylimidazole, 2-methyl-1-vinylimidazole, N-allylimidazole, 2-phenylvinyl-1H-imidazole or 2-vinyl-(9ci)-1H-benzimidazole.

8. The process for removing petroleum acid by electric field coupled continuous solid phase extraction according to claim 6, characterized in that: The halogenated alkylamine in step 1 is 3-chloropropylamine, 4-chlorobutylamine, 4-bromo-1-butylamine or 5-bromopentylamine; the halogenated hydrocarbon is 1-bromooctane, 1-chlorodecane, 1-bromododecane or 1-bromohexadecane.

9. The process for removing petroleum acid by electric field coupled continuous solid phase extraction according to claim 6, characterized in that: The comonomer in step 2 is styrene, divinylbenzene, vinylpyridine or vinylnaphthalene.

10. The process for removing petroleum acid by electric field coupled continuous solid phase extraction according to claim 6, characterized in that: The free radical initiator described in step 2 is azobisisobutyronitrile, azobisisoheptanenitrile, isopropylbenzene hydroperoxide, tert-butyl hydroperoxide, dibenzoyl peroxide, cyclohexanone peroxide, di-tert-butyl peroxide or diisopropylbenzene peroxide.

Images