CN109704907B - Method for preparing hexane from raffinate oil - Google Patents

Method for preparing hexane from raffinate oil Download PDF

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CN109704907B
CN109704907B CN201711010920.1A CN201711010920A CN109704907B CN 109704907 B CN109704907 B CN 109704907B CN 201711010920 A CN201711010920 A CN 201711010920A CN 109704907 B CN109704907 B CN 109704907B
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hexane
cyclohexane
methylcyclopentane
isohexane
tower
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CN109704907A (en
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刘银川
孙翟宗
胡松
杨卫胜
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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Abstract

The invention relates to a method for preparing hexane from raffinate oil, wherein aromatic raffinate oil F passes through a first rectifying tower, a material flow I containing C5 and the following components is obtained from the top of the first rectifying tower, a material flow II containing isohexane, normal hexane, methylcyclopentane and benzene is obtained at the lateral line position, a material flow III containing C7 and the above components of cyclohexane is obtained at the position below the feeding position, a C6 component in the material flow III passes through a reverse isomerization reactor, the obtained methylcyclopentane is recycled to the first rectifying tower through the reaction, a material flow IV is obtained from the material flow II through a hydroisomerization reactor, the material flow IV is separated to obtain isohexane, normal hexane, methylcyclopentane and cyclohexane, and the methylcyclopentane is recycled to the isomerization reactor. The invention effectively solves the problems of low comprehensive utilization rate of the existing aromatic raffinate oil, low n-hexane yield, low cyclohexane yield, single hexane component and low product added value, and can be applied to industrial continuous production.

Description

Method for preparing hexane from raffinate oil
Technical Field
The invention relates to a method for preparing hexane from raffinate oil, in particular to a method for preparing normal hexane, isohexane and cyclohexane, which effectively improves the additional value of aromatic raffinate oil.
Background
The raffinate oil is a byproduct in aromatic hydrocarbon production, mainly contains saturated hydrocarbon, part of olefin, low aromatic hydrocarbon content, extremely low contents of impurities such as sulfur, nitrogen, heavy metal and the like, and is suitable for producing high-quality solvent oil, high-added-value hexane oil and the like. The raffinate oil has high naphthene content, mainly comprising cyclopentane, methylcyclopentane, cyclohexane and the like, the naphthene can be used as the raffinate oil product for export, and the paraffin is sent to a cracking device as a raw material, so that the added value of the raffinate oil is greatly improved.
Cyclohexane is an important basic organic chemical raw material and organic solvent. The prior cyclohexane and the derivative products thereof are produced by a benzene hydrogenation method in China, and have high cost and small production capacity. The high-purity cyclohexane obtained by extracting and rectifying light hydrocarbon from the oil field has huge potential and wide prospect. Cyclohexane is mainly used in foreign countries to produce nylon-6 and nylon-66. N-hexane is a colorless transparent liquid, one of hydrocarbon solvents with wide industrial application, and is also the most representative non-polar solvent. N-hexane is an organic solvent, has good viscosity, and is commonly used in rubber food, pharmacy, perfume, shoemaking, adhesive tape, ball making, grinding, leather, textile, furniture, paint industry, or for dilution, or for cleaning solvent, or for viscose. Isohexane has the characteristics of no toxicity, no sulfur, no aromatic hydrocarbon, good solubility, good stability, no damage to ozone layer, no corrosion to metal, plastic, glass and ceramic, strong permeability and easy drying. With the improvement of the national requirement on environmental protection, the cleaning agent is mainly used as a low-boiling-point hydrocarbon solvent to eliminate ODS (ozone depleting substance) cleaning agent and is widely used in the cleaning industry.
Alkane hydroisomerization is one of the important reactions in the petroleum refining process, and is mainly applied to producing high-quality fuel oil and high-grade lubricating oil. Among them, the hydroisomerization of light paraffins can produce gasoline blending components of high octane number, while the hydroisomerization of long-chain paraffins is mainly used to improve the low-temperature flow properties of middle distillates (jet fuel and diesel fuel) and lubricating oils. The catalyst plays a core role in the hydroisomerization reaction, and the hydroisomerization catalyst is a bifunctional catalyst and has both hydrogenation-dehydrogenation activity and acidic activity. Such catalysts are required to have not only hydrogenation activity but also isomerization activity. The acidic carrier must have several functions: increasing the effective surface area of the catalyst; providing a suitable pore structure; providing an acid center; the mechanical strength of the catalyst is improved; the thermal stability of the catalyst is improved; the antitoxic ability of the catalyst is increased; the consumption of metal components is saved, and the cost is reduced. The application of molecular sieves has promoted the development of hydroisomerization catalysts and mechanism research. According to a classical bifunctional mechanism, the selectivity of the amorphous bifunctional catalyst to the hydroisomerization reaction can be regulated and controlled by adjusting the strength and the weakness of the metal and the acidity of the amorphous bifunctional catalyst.
CN 104718179 a discloses a new method for preparing cyclohexane from methylcyclopentane and benzene, which uses a hydrocarbon mixture of Methylcyclopentane (MCP) and benzene as raw materials, first converts benzene into cyclohexane through a hydrogenation step, and then isomerizes into cyclohexane in the presence of an acidic ionic liquid, wherein the target product is cyclohexane.
CN 201999872U discloses a device for preparing hexane from oil refining raffinate. The utility model discloses a device for preparing hexane from oil refining raffinate, which comprises a lightness-removing tower, a hexane tower and a hydrogenation reactor, wherein the lightness-removing tower is connected with a lightness-removing tower feed pump, and a lightness-removing tower preheater is connected between the lightness-removing tower feed pump and the lightness-removing tower; and the tower kettle of the hexane tower is connected with the lightness-removing tower preheater through a hexane tower kettle liquid pump. The utility model discloses a preparation of hexane is carried out through the method that adopts oil refining raffinate oil to carry out the rectification, and separation is rectified by lightness-removing tower and hexane tower twin columns now, and back hydrofining takes hexane tower cauldron liquid out as the heat transfer medium of lightness-removing tower pre-heater, utilizes the ejection of compact heat of hexane tower cauldron to preheat the raw materials, has rationally coupled the energy of device, has reduced the scale of device, has reduced the energy consumption of device.
CN 105143410 a discloses a hydroisomerization catalyst based on FE-containing molecular sieves. Hydroisomerization of a paraffinic hydrocarbon feed derived from renewable sources is effectively achieved by passing the feed over a hydroisomerization catalyst comprising a crystalline metallosilicate molecular sieve in which a portion of the crystalline framework comprises iron, in the presence of hydrogen.
CN 1432550A discloses a method for hydroisomerization reaction of straight-chain alkane, which comprises contacting a raw material containing straight-chain alkane and hydrogen with a hydroisomerization catalyst under the condition of hydroisomerization reaction, and is characterized in that the raw material contains 5-10000 ppm, preferably 10-4000 ppm of a compound containing strong electronegative elements as a reaction auxiliary agent. When the method is adopted to carry out hydroisomerization reaction, higher reaction equilibrium conversion rate and better isoparaffin selectivity can be obtained.
CN 103588603A discloses a process method for producing n-hexane by using reformed raffinate oil; pretreating raffinate oil in a five decarburization towers, distilling out light five mixed carbon components with low boiling points from the tops of the five decarburization towers, and feeding the seven mixed carbon components with six carbon atoms at the bottoms into a seven decarburization tower; the mixed carbon six-carbon seven component is treated by the decarbonization seven tower, the mixed carbon seven component is discharged from the bottom of the tower, and the unseparated mixed component enters the carbon six-separation tower from the top of the tower; after being treated by the carbon six separation tower, the distillate at the tower top is mixed carbon six components, and the mixture at the tower bottom enters the extraction rectifying tower; extracting and separating the top fraction of the tower into high-purity n-hexane, and allowing the mixture at the bottom of the tower to enter a solvent recovery tower; the distillate at the tower top of the solvent recovery tower is methyl cyclopentane, and the extractant at the tower bottom is recycled; the method solves the problem of comprehensive utilization of the reformed raffinate oil in an oil refinery, improves the deep processing level of petroleum products, ensures that the concentration of n-hexane products reaches more than 95 percent, and simultaneously recycles the five mixed carbon components, the six mixed carbon components and the seven mixed carbon components.
According to the invention, the raffinate oil raw material is passed through the first rectifying tower, the hydroisomerization unit and the product separation unit to finally obtain isohexane, n-hexane and cyclohexane products, and the cyclohexane in the raw material is converted into methylcyclopentane to be recycled to the system through the anti-isomerization of the first rectifying tower bottoms, so that the loss of cyclohexane in the aromatic raffinate oil of the raw material is effectively avoided, and the comprehensive utilization rate of the aromatic raffinate oil is improved.
Disclosure of Invention
The invention aims to solve the problems of low comprehensive utilization rate of the existing raffinate oil, low n-hexane yield, low cyclohexane yield, single hexane component and low product additional value, and provides a novel method for preparing hexane from raffinate oil.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows, and the method for preparing the hexane from the raffinate oil comprises the following steps:
(1) the raffinate oil passes through a first rectifying tower, a component material flow I with the content of C5 and the content below is obtained through separation at the top of the tower, a material flow II containing isohexane, normal hexane, methylcyclopentane and benzene is obtained at the lateral line position, and a component material flow III with the content of C7 and the content above is obtained at the position below the feeding position;
(2) the material flow II is subjected to a hydroisomerization reactor to obtain a material flow IV;
(3) and separating the material flow IV to obtain isohexane, n-hexane, methylcyclopentane and cyclohexane.
In the above technical solution, the raw raffinate oil in step (1) preferably contains C5 and the following components, and preferably contains a small amount of C5 and the following components.
In the above technical solution, preferably, the component separated from the top of the step (1) further contains a C6 component; preferably a minor amount of a C6 component.
In the above technical solution, preferably, the component obtained below the feeding position of step (1) further contains a C6 component; preferably a minor amount of a C6 component.
In the above technical solution, preferably, the main component of the C6 component is cyclohexane.
Because the components in the raw material raffinate oil are various and complex and have various azeotropes, especially the plurality of components such as cyclohexane and Dimethylpentane (DMP) have an azeotropic phenomenon, in the first rectifying tower, the cyclohexane in the raw material aromatic raffinate oil is lost, and most of the cyclohexane enters the anti-isomerization unit from the first rectifying tower kettle, so that the concentration of the azeotropic components such as Dimethylpentane (DMP) in the side stream of the first rectifying tower is reduced, and the purity of the product cyclohexane is prevented from being influenced. Meanwhile, as the benzene and the normal hexane are subjected to azeotropic distillation, a part of benzene is extracted from the top of the second rectifying tower. The azeotropes common in the raw raffinate oil are listed in table 1:
TABLE 1
Azeotropes Azeotropic Point (. degree. C.)
Cyclohexane and 2, 2-dimethylpentane 78.9
Cyclohexane and 2, 4-dimethylpentane 80.29
Cyclohexane and 2,2, 3-trimethylbutane 80.23
N-hexane and benzene 68.93
In the above technical scheme, preferably, the component C6 is passed through a de-isomerization reactor, and the methylcyclopentane obtained by the reaction is recycled to the first rectification column. More preferably, the material flow III is firstly separated by a heavy component removal rectifying tower to obtain a mixture M1 containing high-concentration cyclohexane, the mixture M1 enters a reverse isomerization unit to convert the cyclohexane into methylcyclopentane and then is circulated to the first rectifying tower, the pressure of the reverse isomerization reaction is preferably 0.0-0.35 MPag, and the temperature is preferably 50-115 ℃; the operating pressure of the de-weighting tower is 0.0 to 0.4MPag, and more preferably 0.0 to 0.25 MPag.
In the above technical scheme, preferably, the mass concentration of isohexane in the material flow II is not less than the mass concentration of n-hexane.
In the isomerization reaction, there is also an equilibrium reversible reaction between isohexane and n-hexane. Therefore, in order to improve the yield of the n-hexane product, during the cutting process of the first rectifying tower and the second rectifying tower, the mass concentration of the isohexane is preferably not less than that of the n-hexane, so that the conversion of the n-hexane is reduced.
In the above technical scheme, preferably, benzene and unsaturated hydrocarbons are removed from the hydroisomerization reactor in step (3), benzene and other unsaturated hydrocarbons are converted into cyclohexane and saturated hydrocarbons, and methylcyclopentane is converted into cyclohexane. The pressure of the pressure hydrogenation reactor of the hydroisomerization reactor is preferably 0.3-4 MPag, more preferably 1.5-2.5 MPag, and the temperature is preferably 60-450 ℃, more preferably 100-300 ℃.
In the above technical scheme, preferably, the methylcyclopentane in the step (3) is recycled to the hydroisomerization reactor.
In the above technical solution, preferably, isohexane with a mass concentration of not less than 90% and/or n-hexane with a mass concentration of not less than 60% and/or cyclohexane with a mass concentration of not less than 99% is obtained by separation in step (3), isohexane with a mass concentration of not less than 99% and/or n-hexane with a mass concentration of not less than 80% and/or cyclohexane with a mass concentration of not less than 99.9% is obtained by separation.
In the above technical solution, preferably, isohexane, n-hexane, methylcyclopentane and cyclohexane are extracted from the extraction points above the feeding positions of the isohexane column, the n-hexane column, the methylcyclopentane column and the cyclohexane column, respectively; more preferably, the isohexane tower and the normal hexane tower adopt a dividing wall tower, isohexane is extracted from the top of the dividing wall tower, normal hexane is extracted from the side line of the dividing wall tower, and a mixture containing methylcyclopentane and cyclohexane is extracted from the bottom of the dividing wall tower and enters the methylcyclopentane tower.
Because the separation precision requirement of the product isohexane and n-hexane is not high, the isohexane is a mixture containing 2-methylpentane and 3-methylpentane, and the n-hexane is a mixture with the mass concentration of more than 60%, and a dividing wall tower is adopted, the product requirement is met, and the energy consumption can be effectively reduced.
In the above technical solution, preferably, the operating pressure of the first rectifying tower, the isohexane tower, the n-hexane tower, the methylcyclopentane tower and the cyclohexane tower is 0.0-0.8 MPag, and more preferably 0.0-0.3 MPag; the operation pressure of the dividing wall tower is 0.0-0.35 MPag.
According to the invention, the raffinate oil of the raw material is subjected to cutting of C5 and C7 components and concentration control of isohexane, n-hexane, methylcyclopentane and cyclohexane which are key components through a first rectifying tower, benzene is converted into cyclohexane through a hydroisomerization unit, the methylcyclopentane is converted into cyclohexane, the isohexane and the n-hexane are subjected to balanced conversion, isohexane, n-hexane and cyclohexane products are finally obtained through rectification separation, cyclohexane in the bottom liquid of the first rectifying tower is subjected to reverse isomerization, and the cyclohexane in the raw material is converted into the methylcyclopentane for recycling, so that cyclohexane loss in the raffinate oil of the aromatic hydrocarbon of the raw material is effectively avoided, other materials can still be used as cracking and reforming raw materials, the additional value of the raffinate oil of the aromatic hydrocarbon is greatly improved, and the raffinate oil of the aromatic hydrocarbon can be applied to industrial production.
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention in any way.
Drawings
FIG. 1 is a schematic diagram of a process for preparing hexane from raffinate. The method comprises the following steps of feeding aromatic raffinate oil F containing isohexane, normal hexane, methylcyclopentane, cyclohexane and benzene into a first rectifying tower, obtaining a material flow I containing C5 and the following components from the top of the first rectifying tower, obtaining a material flow II containing the isohexane, the normal hexane, the methylcyclopentane and the benzene at the lateral line position, obtaining a material flow III containing C7 and the above components of the cyclohexane at the position below the feeding position, obtaining a material flow IV from the material flow II through a hydroisomerization reactor, and obtaining the isohexane, the normal hexane, the methylcyclopentane and the cyclohexane from the material flow IV through separation, wherein the methylcyclopentane is circulated to the isomerization reactor.
As shown in FIG. 1, F is an aromatic raffinate raw material, I is a mixture containing a C5 component and a small amount of a C6 component, II is a mixture containing isohexane, n-hexane, methylcyclopentane and benzene, IV is a reaction product after II hydroisomerization, and III is a mixture containing cyclohexane, DMP and cyclohexane with a boiling point at normal pressure of more than or equal to that of cyclohexane. 1 is a first rectifying tower, 2 is a hydroisomerization unit, and 3 is a separation unit.
FIG. 2 shows the hydroisomerization product stream IV which is sequentially separated into isohexane, n-hexane, methylcyclopentane and cyclohexane from the above-mentioned position of the feed by 4 rectifying columns.
As shown in fig. 2, IV is a reaction product after hydroisomerization, S1 is isohexane, S2 is n-hexane, S3 is methylcyclopentane, S4 is cyclohexane, and S5 is a mixture of cyclohexane having a boiling point at normal pressure or higher. 7 is an isohexane column, 8 is an n-hexane column, 9 is a methylcyclopentane column, and 10 is a cyclohexane column.
FIG. 3 shows that the hydroisomerization product stream IV is passed through a dividing wall column to obtain isohexane from the top of the column, n-hexane from the side of the column, the bottoms of the dividing wall column are fed into a methylcyclopentane column, methylcyclopentane is obtained by separation from the position above the feed of the methylcyclopentane column, the bottoms of the methylcyclopentane column are fed into a cyclohexane column, and cyclohexane is obtained by separation from the position above the feed of the cyclohexane column.
As shown in fig. 3, IV is a reaction product after hydroisomerization, S6 is isohexane, S7 is n-hexane, S8 is methylcyclopentane, S9 is cyclohexane, and S10 is a mixture of cyclohexane having a boiling point at normal pressure or higher; 11 is a dividing wall column, 12 is a methylcyclopentane column, and 13 is a cyclohexane column.
FIG. 4 shows that the bottom material flow III of the first rectifying tower firstly passes through a de-weighting tower, a mixture containing cyclohexane is obtained by separation from a position above the feeding of the de-weighting tower and enters a de-isomerization reaction unit, in the de-isomerization reaction unit, the cyclohexane is converted into methyl cyclopentane, and the de-isomerization reaction product returns to the first rectifying tower.
As shown in fig. 4, III is a mixture containing cyclohexane, DMP and cyclohexane having a boiling point at atmospheric pressure or higher, M1 is a mixture containing cyclohexane, M2 is a mixture containing cyclohexane and methylcyclopentane, and M3 is a mixture having a boiling point at atmospheric pressure or higher; 14 is a de-weighting tower, and 15 is an anti-isomerization reaction unit.
Detailed Description
[ example 1 ]
A process for the preparation of hexane from an aromatic raffinate as shown in FIG. 1. The raffinate oil F containing 0.5 wt% of C5 and the following components, 15 wt% of isohexane, 15 wt% of n-hexane, 20 wt% of methylcyclopentane, 20 wt% of cyclohexane and 0.2 wt% of benzene is passed through a first rectifying tower, a stream I containing C5 and the following components is obtained from the top of the first rectifying tower, a stream II containing isohexane, n-hexane, methylcyclopentane and benzene is obtained at the side line position, a stream III containing C7 and the above components of cyclohexane is obtained at the position below the feeding position, the component C6 in the stream III is passed through a reverse isomerization reactor, the obtained methylcyclopentane after reaction is recycled to the first rectifying tower, the stream II is passed through a hydroisomerization reactor to obtain a stream IV, and the stream IV is separated to obtain isohexane, n-hexane, methylcyclopentane and cyclohexane, wherein the methylcyclopentane is recycled to the isomerization reactor, as shown in figure 2.
The first rectifying tower, the isohexane tower, the n-hexane tower, the methylcyclopentane tower and the cyclohexane tower are all normal pressure towers.
The hydroisomerization reactor was operated at 2.5MPag, a reaction temperature of 320 ℃, a benzene conversion of > 99.5%, a methylcyclopentane conversion of > 60%, and a cyclohexane selectivity of > 99%.
The purity of the obtained isohexane product is more than 98.5 wt%, the purity of the normal hexane product is more than 70 wt%, and the purity of the cyclohexane product is more than 99.9 wt%, wherein the mass concentration of methylcyclopentane is less than 150ppm, and the obtained product meets the standard of superior products;
[ example 2 ]
The implementation is similar to example 1. The raffinate oil F containing 0.5 wt% of C5 and the following components, 15 wt% of isohexane, 15 wt% of n-hexane, 20 wt% of methylcyclopentane, 20 wt% of cyclohexane and 0.2 wt% of benzene is passed through a first rectifying tower, a stream I containing C5 and the following components is obtained from the top of the first rectifying tower, a stream II containing isohexane, n-hexane, methylcyclopentane and benzene is obtained at the side line position, a stream III containing C7 and the above components of cyclohexane is obtained at the position below the feeding position, the component C6 in the stream III is passed through a reverse isomerization reactor, the obtained methylcyclopentane after reaction is recycled to the first rectifying tower, the stream II is passed through a hydroisomerization reactor to obtain a stream IV, and the stream IV is separated to obtain isohexane, n-hexane, methylcyclopentane and cyclohexane, wherein the methylcyclopentane is recycled to the isomerization reactor, as shown in figure 2.
Except for the change in operating parameters:
the operation pressure of the normal hexane tower, the operation pressure of the methyl cyclopentane tower and the operation pressure of the cyclohexane tower are all normal pressure towers;
the first rectification column and isohexane column operating pressures were 0.26 MPag;
the hydroisomerization reactor was operated at 3.8MPag, a reaction temperature of 320 ℃, a benzene conversion of > 99%, a methylcyclopentane conversion of > 65%, and a cyclohexane selectivity of > 99.2%.
The purity of the product isohexane is more than 92.5 wt%, the purity of the product n-hexane is more than 65 wt%, and the purity of the product cyclohexane is more than 99 wt%.
[ example 3 ]
The implementation is similar to example 1. The raffinate oil F containing 10 wt% of C5 and the following components, 15 wt% of isohexane, 15 wt% of normal hexane, 20 wt% of methylcyclopentane, 20 wt% of cyclohexane and 0.03 wt% of benzene is passed through a first rectifying tower, a stream I containing C5 and the following components is obtained from the top of the first rectifying tower, a stream II containing isohexane, normal hexane, methylcyclopentane and benzene is obtained at the side line position, a stream III containing C7 and the above components of cyclohexane is obtained at the position below the feed, the component C6 in the stream III is passed through a reverse isomerization reactor, the obtained methylcyclopentane is recycled to the first rectifying tower, the stream II is passed through a hydroisomerization reactor to obtain a stream IV, and the stream IV is separated to obtain isohexane, normal hexane, methylcyclopentane and cyclohexane, as shown in figure 2, wherein the methylcyclopentane is recycled to the isomerization reactor.
Except for the change in operating parameters:
the operating pressures of the first rectifying tower, the isohexane tower and the normal hexane tower are all normal pressure towers;
the operating pressure of the methylcyclopentane column and the cyclohexane column was 0.31 MPag;
the hydroisomerization reactor was operated at 1.4MPag, a reaction temperature of 130 ℃, a benzene conversion of > 98%, a methylcyclopentane conversion of > 52%, and a cyclohexane selectivity of > 99.5%.
The purity of the product isohexane is more than 93 wt%, the purity of the product n-hexane is more than 60 wt%, and the purity of the product cyclohexane is more than 99.5 wt%.
[ example 4 ]
The implementation is similar to example 1. The raffinate oil F containing 0.5 wt% of C5 and the following components, 15 wt% of isohexane, 15 wt% of n-hexane, 20 wt% of methylcyclopentane, 20 wt% of cyclohexane and 0.2 wt% of benzene is passed through a first rectifying tower, a stream I containing C5 and the following components is obtained from the top of the first rectifying tower, a stream II containing isohexane, n-hexane, methylcyclopentane and benzene is obtained at the side line position, a stream III containing C7 and the above components of cyclohexane is obtained at the position below the feeding position, the component C6 in the stream III is passed through a reverse isomerization reactor, the obtained methylcyclopentane after reaction is recycled to the first rectifying tower, the stream II is passed through a hydroisomerization reactor to obtain a stream IV, and the stream IV is separated to obtain isohexane, n-hexane, methylcyclopentane and cyclohexane, wherein the methylcyclopentane is recycled to the isomerization reactor, as shown in figure 2.
Except for the change in operating parameters:
the operation pressures of the first rectifying tower, the isohexane tower, the methylcyclopentane tower and the cyclohexane tower are all normal pressure towers;
the operating pressure of the n-hexane tower is 0.36 MPag;
the hydroisomerization reactor was operated at 0.2MPag, a reaction temperature of 100 ℃, a benzene conversion of > 98%, a methylcyclopentane conversion of > 45%, and a cyclohexane selectivity of > 99%.
The purity of the product isohexane is more than 95 wt%, the purity of the product n-hexane is more than 65 wt%, and the purity of the product cyclohexane is more than 99.5 wt%.
[ example 5 ]
The implementation is similar to example 1. The method comprises the following steps of enabling raffinate oil F containing 0.5 wt% of C5 and the following components, 15 wt% of isohexane, 15 wt% of n-hexane, 20 wt% of methylcyclopentane, 20 wt% of cyclohexane and 0.2 wt% of benzene to pass through a first rectifying tower, obtaining a material flow I containing C5 and the following components from the top of the first rectifying tower, obtaining a material flow II containing isohexane, n-hexane, methylcyclopentane and benzene at the side line position, obtaining a material flow III containing C7 and the above components of cyclohexane at the position below the feeding position, enabling the C6 component in the material flow III to pass through a reverse isomerization reactor, recycling the obtained methylcyclopentane through reaction to the first rectifying tower, obtaining a material flow IV through a hydroisomerization reactor, and separating the material flow IV to obtain isohexane, n-hexane, methylcyclopentane and cyclohexane, wherein the methylcyclopentane is recycled to the isomerization reactor.
Except that a dividing wall column was used instead of the isohexane column and the n-hexane column as shown in FIG. 3, the operating pressure of the dividing wall column was 0.06MPag, and the other operating parameters were unchanged.
The first rectifying tower, the methyl cyclopentane tower and the cyclohexane tower are all normal pressure towers.
The hydroisomerization reactor was operated at 2.5MPag, a reaction temperature of 320 ℃, a benzene conversion of > 99.5%, a methylcyclopentane conversion of > 60%, and a cyclohexane selectivity of > 99%.
The purity of the obtained isohexane product is more than 98.5 wt%, the purity of the normal hexane product is more than 70 wt%, and the purity of the cyclohexane product is more than 99.9 wt%, wherein the mass concentration of methylcyclopentane is less than 150ppm, and the obtained product meets the standard of superior products;
after the dividing wall tower is adopted, compared with the two towers of isohexane tower and n-hexane tower adopted in the embodiment 1, the energy consumption is saved by about 17%.
[ example 6 ]
The implementation is similar to example 1. The method comprises the following steps of enabling raffinate oil F containing 0.5 wt% of C5 and the following components, 15 wt% of isohexane, 15 wt% of n-hexane, 20 wt% of methylcyclopentane, 20 wt% of cyclohexane and 0.2 wt% of benzene to pass through a first rectifying tower, obtaining a material flow I containing C5 and the following components from the top of the first rectifying tower, obtaining a material flow II containing isohexane, n-hexane, methylcyclopentane and benzene at the side line position, obtaining a material flow III containing C7 and the above components of cyclohexane at the position below the feeding position, enabling the C6 component in the material flow III to pass through a reverse isomerization reactor, recycling the obtained methylcyclopentane through reaction to the first rectifying tower, obtaining a material flow IV through a hydroisomerization reactor, and separating the material flow IV to obtain isohexane, n-hexane, methylcyclopentane and cyclohexane, wherein the methylcyclopentane is recycled to the isomerization reactor.
Except that a dividing wall column was used instead of the isohexane column and the n-hexane column as shown in FIG. 3, the operating pressure of the dividing wall column was 0.29MPag, and the other operating parameters were unchanged.
The first rectifying tower, the methyl cyclopentane tower and the cyclohexane tower are all normal pressure towers.
The hydroisomerization reactor was operated at 2.5MPag, a reaction temperature of 320 ℃, a benzene conversion of > 99.5%, a methylcyclopentane conversion of > 60%, and a cyclohexane selectivity of > 99%.
The purity of the obtained isohexane product is more than 98.5 wt%, the purity of the normal hexane product is more than 70 wt%, and the purity of the cyclohexane product is more than 99.9 wt%, wherein the mass concentration of methylcyclopentane is less than 150ppm, and the obtained product meets the standard of superior products;
after the dividing wall tower is adopted, compared with the two towers of isohexane tower and n-hexane tower adopted in the embodiment 1, the energy consumption is saved by about 15%.
[ example 7 ]
Passing raffinate F containing 0.5 wt% of C5 and the following components, 10 wt% of isohexane, 15 wt% of n-hexane, 20 wt% of methylcyclopentane, 20 wt% of cyclohexane and 0.2 wt% of benzene through a first rectifying tower, obtaining a stream I containing C5 and the following components from the top of the first rectifying tower, obtaining a stream II containing isohexane, n-hexane, methylcyclopentane and benzene at a side line position, obtaining a stream III containing C7 and the above components of cyclohexane at a position below a feeding position, passing a component C6 in the stream III through a reverse isomerization reactor, recycling the obtained methylcyclopentane after reaction to the first rectifying tower, passing the stream II through a hydroisomerization reactor to obtain a stream IV, and separating the stream IV to obtain isohexane, n-hexane, methylcyclopentane and cyclohexane, wherein the methylcyclopentane is recycled to the isomerization reactor as shown in figure 2.
The operating parameters were the same as in example 1.
The first rectifying tower, the isohexane tower, the n-hexane tower, the methylcyclopentane tower and the cyclohexane tower are all normal pressure towers.
The hydroisomerization reactor was operated at 2.5MPag, a reaction temperature of 320 ℃, a benzene conversion of > 99.5%, a methylcyclopentane conversion of > 60%, and a cyclohexane selectivity of > 99%.
The purity of the obtained isohexane product is more than 98.5 wt%, the purity of the normal hexane product is more than 70 wt%, and the purity of the cyclohexane product is more than 99.9 wt%, wherein the mass concentration of methylcyclopentane is less than 150ppm, and the obtained product meets the standard of superior products;
compared with example 1, the n-hexane product yield is reduced by 17%.
[ example 8 ]
The raffinate F containing 0.5 wt% of C5 and the following components, 12 wt% of isohexane, 18 wt% of n-hexane, 20 wt% of methylcyclopentane, 20 wt% of cyclohexane and 0.2 wt% of benzene is passed through a first rectifying tower, a stream I containing C5 and the following components is obtained from the top of the first rectifying tower, a stream II containing isohexane, n-hexane, methylcyclopentane and benzene is obtained at the side line position, a stream III containing C7 and the above components of cyclohexane is obtained at the position below the feeding position, the component C6 in the stream III is passed through a reverse isomerization reactor, the obtained methylcyclopentane after reaction is recycled to the first rectifying tower, the stream II is passed through a hydroisomerization reactor to obtain a stream IV, and the stream IV is separated to obtain isohexane, n-hexane, methylcyclopentane and cyclohexane, as shown in figure 2, wherein the methylcyclopentane is recycled to the isomerization reactor.
The operating parameters were the same as in example 1.
The first rectifying tower, the isohexane tower, the n-hexane tower, the methylcyclopentane tower and the cyclohexane tower are all normal pressure towers.
The hydroisomerization reactor was operated at 2.5MPag, a reaction temperature of 320 ℃, a benzene conversion of > 99.5%, a methylcyclopentane conversion of > 60%, and a cyclohexane selectivity of > 99%.
The purity of the obtained isohexane product is more than 98.5 wt%, the purity of the normal hexane product is more than 70 wt%, and the purity of the cyclohexane product is more than 99.9 wt%, wherein the mass concentration of methylcyclopentane is less than 150ppm, and the obtained product meets the standard of superior products;
the yield of the n-hexane product is reduced by 17 percent.
[ example 9 ]
The raffinate oil F containing 0.001 wt% of C5 and the following components, 15 wt% of isohexane, 15 wt% of n-hexane, 24 wt% of methylcyclopentane, 20 wt% of cyclohexane and 0.2 wt% of benzene is passed through a first rectifying tower, a stream I containing C5 and the following components is obtained from the top of the first rectifying tower, a stream II containing isohexane, n-hexane, methylcyclopentane and benzene is obtained at the side line position, a stream III containing C7 and the above components of cyclohexane is obtained at the position below the feeding position, the component C6 in the stream III is passed through a reverse isomerization reactor, the obtained methylcyclopentane after reaction is recycled to the first rectifying tower, the stream II is passed through a hydroisomerization reactor to obtain a stream IV, and the stream IV is separated to obtain isohexane, n-hexane, methylcyclopentane and cyclohexane, wherein the methylcyclopentane is recycled to the isomerization reactor, as shown in figure 2.
The operating parameters were the same as in example 1.
The first rectifying tower, the isohexane tower, the n-hexane tower, the methylcyclopentane tower and the cyclohexane tower are all normal pressure towers.
The hydroisomerization reactor was operated at 2.5MPag, a reaction temperature of 320 ℃, a benzene conversion of > 99.5%, a methylcyclopentane conversion of > 60%, and a cyclohexane selectivity of > 99%.
The purity of the obtained isohexane product is more than 98.5 wt%, the purity of the normal hexane product is more than 70 wt%, and the purity of the cyclohexane product is more than 99.9 wt%, wherein the mass concentration of methylcyclopentane is less than 150ppm, and the obtained product meets the standard of superior products;
the cyclohexane product yield was increased by 20% compared to example 1.
[ example 10 ]
The implementation is similar to example 1. The raffinate oil F containing 0.5 wt% of C5 and the following components, 15 wt% of isohexane, 15 wt% of n-hexane, 20 wt% of methylcyclopentane, 20 wt% of cyclohexane and 0.2 wt% of benzene is passed through a first rectifying tower, a stream I containing C5 and the following components is obtained from the top of the first rectifying tower, a stream II containing isohexane, n-hexane, methylcyclopentane and benzene is obtained at the side line position, a stream III containing C7 and the above components of cyclohexane is obtained at the position below the feeding position, the component C6 in the stream III is passed through a reverse isomerization reactor, the obtained methylcyclopentane after reaction is recycled to the first rectifying tower, the stream II is passed through a hydroisomerization reactor to obtain a stream IV, and the stream IV is separated to obtain isohexane, n-hexane, methylcyclopentane and cyclohexane, wherein the methylcyclopentane is recycled to the isomerization reactor, as shown in figure 2.
The operating parameters were the same as in example 1.
The first rectifying tower, the isohexane tower, the n-hexane tower, the methylcyclopentane tower and the cyclohexane tower are all normal pressure towers.
The hydroisomerization reactor was operated at 2.5MPag, a reaction temperature of 320 ℃, a benzene conversion of > 99.5%, a methylcyclopentane conversion of > 60%, and a cyclohexane selectivity of > 99%.
Except that the stream III firstly passes through a de-heavy column to obtain a mixture M1 containing cyclohexane from the top of the column, and then the cyclohexane is converted into methylcyclopentane through de-isomerization to obtain a stream M2 containing the methylcyclopentane and cyclohexane, and the stream is recycled to the first rectifying column, as shown in FIG. 4.
The operation pressure of the reverse isomerization reaction is 0.23MPag, the reaction temperature is 80 ℃, the conversion rate is more than 35 percent, and the selectivity is more than 99 percent;
the operating pressure of the de-weighting tower was 0.04 MPag;
the purity of the obtained isohexane product is more than 98.5 wt%, the purity of the normal hexane product is more than 70 wt%, and the purity of the cyclohexane product is more than 99.9 wt%, wherein the mass concentration of methylcyclopentane is less than 150ppm, and the obtained product meets the standard of superior products;
the cyclohexane product yield was increased by 50% compared to example 1.
[ example 11 ]
The implementation is similar to example 10. The raffinate oil F containing 0.5 wt% of C5 and the following components, 15 wt% of isohexane, 15 wt% of n-hexane, 20 wt% of methylcyclopentane, 20 wt% of cyclohexane and 0.2 wt% of benzene is passed through a first rectifying tower, a stream I containing C5 and the following components is obtained from the top of the first rectifying tower, a stream II containing isohexane, n-hexane, methylcyclopentane and benzene is obtained at the side line position, a stream III containing C7 and the above components of cyclohexane is obtained at the position below the feeding position, the component C6 in the stream III is passed through a reverse isomerization reactor, the obtained methylcyclopentane after reaction is recycled to the first rectifying tower, the stream II is passed through a hydroisomerization reactor to obtain a stream IV, and the stream IV is separated to obtain isohexane, n-hexane, methylcyclopentane and cyclohexane, wherein the methylcyclopentane is recycled to the isomerization reactor, as shown in figure 2.
The operating parameters were the same as in example 1.
The first rectifying tower, the isohexane tower, the n-hexane tower, the methylcyclopentane tower and the cyclohexane tower are all normal pressure towers.
The hydroisomerization reactor was operated at 2.5MPag, a reaction temperature of 320 ℃, a benzene conversion of > 99.5%, a methylcyclopentane conversion of > 60%, and a cyclohexane selectivity of > 99%.
The stream III firstly passes through a de-heavy column, a mixture M1 containing cyclohexane is obtained from the top of the column, and then the cyclohexane is converted into methylcyclopentane through anti-isomerization, so that a stream M2 containing the methylcyclopentane and cyclohexane is obtained and recycled to the first rectifying column, as shown in figure 4.
Except that the operating parameters of the anti-isomerization reaction and the de-heavies column were changed:
the operation pressure of the reverse isomerization reaction is 0.02MPag, the reaction temperature is 50 ℃, the conversion rate is more than 20 percent, and the selectivity is more than 99 percent;
the operating pressure of the de-heavies column was 0.27 MPag;
the purity of the obtained isohexane product is more than 98.5 wt%, the purity of the normal hexane product is more than 70 wt%, and the purity of the cyclohexane product is more than 99.9 wt%, wherein the mass concentration of methylcyclopentane is less than 150ppm, and the obtained product meets the standard of superior products;
the cyclohexane product yield was increased by 46% compared to example 1.
[ example 12 ]
The implementation is similar to example 10. The raffinate oil F containing 0.5 wt% of C5 and the following components, 15 wt% of isohexane, 15 wt% of n-hexane, 20 wt% of methylcyclopentane, 20 wt% of cyclohexane and 0.2 wt% of benzene is passed through a first rectifying tower, a stream I containing C5 and the following components is obtained from the top of the first rectifying tower, a stream II containing isohexane, n-hexane, methylcyclopentane and benzene is obtained at the side line position, a stream III containing C7 and the above components of cyclohexane is obtained at the position below the feeding position, the component C6 in the stream III is passed through a reverse isomerization reactor, the obtained methylcyclopentane after reaction is recycled to the first rectifying tower, the stream II is passed through a hydroisomerization reactor to obtain a stream IV, and the stream IV is separated to obtain isohexane, n-hexane, methylcyclopentane and cyclohexane, wherein the methylcyclopentane is recycled to the isomerization reactor, as shown in figure 2.
The operating parameters were the same as in example 1.
The first rectifying tower, the isohexane tower, the n-hexane tower, the methylcyclopentane tower and the cyclohexane tower are all normal pressure towers.
The hydroisomerization reactor was operated at 2.5MPag, a reaction temperature of 320 ℃, a benzene conversion of > 99.5%, a methylcyclopentane conversion of > 60%, and a cyclohexane selectivity of > 99%.
The stream III firstly passes through a de-heavy column, a mixture M1 containing cyclohexane is obtained from the top of the column, and then the cyclohexane is converted into methylcyclopentane through anti-isomerization, so that a stream M2 containing the methylcyclopentane and cyclohexane is obtained and recycled to the first rectifying column, as shown in figure 4.
Except that the operating parameters of the anti-isomerization reaction and the de-heavies column were changed:
the operation pressure of the reverse isomerization reaction is 0.17MPag, the reaction temperature is 96 ℃, the conversion rate is more than 35 percent, and the selectivity is more than 99.5 percent; the operating pressure of the de-heaving column was 0.11 MPag;
the purity of the obtained isohexane product is more than 98.5 wt%, the purity of the normal hexane product is more than 70 wt%, and the purity of the cyclohexane product is more than 99.9 wt%, wherein the mass concentration of methylcyclopentane is less than 150ppm, and the obtained product meets the standard of superior products;
except that the cyclohexane product yield increased by 48%.

Claims (14)

1. A method for preparing hexane from raffinate oil comprises the following steps:
(1) the raffinate oil passes through a first rectifying tower, a component material flow I with the content of C5 and the content below is obtained through separation at the top of the tower, a material flow II containing isohexane, normal hexane, methylcyclopentane and benzene is obtained at the lateral line position, and a component material flow III with the content of C7 and the content above is obtained at the position below the feeding position;
(2) the material flow II is subjected to a hydroisomerization reactor to obtain a material flow IV;
(3) and separating the material flow IV to obtain isohexane, n-hexane, methylcyclopentane and cyclohexane.
2. The process for producing hexane according to claim 1, characterized in that the raw raffinate oil in the step (1) contains C5 and the following components.
3. The process for producing hexane from raffinate oil according to claim 2, wherein the raw raffinate oil in the step (1) contains a small amount of C5 and the following components.
4. The method for preparing hexane from raffinate oil according to claim 1, wherein the fraction separated at the top of the step (1) further contains C6 fraction.
5. The method for preparing hexane from raffinate oil according to claim 4, wherein the fraction separated at the top of the step (1) further contains a small amount of C6 fraction.
6. The method for preparing hexane from raffinate oil according to claim 1, wherein the fraction obtained below the feeding point of step (1) further contains C6 fraction.
7. The method for preparing hexane from raffinate oil according to claim 6, wherein the fraction obtained below the feeding point of step (1) further contains a small amount of C6 fraction.
8. The method for preparing hexane from raffinate oil as claimed in claim 6, characterized in that the C6 component is passed through a de-isomerization reactor, and the methyl cyclopentane obtained by the reaction is recycled to the first rectification column.
9. The method for preparing hexane from raffinate oil as claimed in claim 1, wherein the mass concentration of isohexane in stream II is not less than the mass concentration of n-hexane.
10. The method for preparing hexane from raffinate oil according to claim 1, wherein benzene and unsaturated hydrocarbon are removed in the hydroisomerization reactor in the step (2).
11. The method for preparing hexane from raffinate oil according to claim 1, wherein n-hexane and isohexane are in equilibrium conversion, and methylcyclopentane and cyclohexane are in equilibrium conversion in the hydroisomerization reactor in the step (2).
12. The process for preparing hexane from raffinate oil according to claim 1, wherein the methylcyclopentane in step (3) is recycled to the isomerization reactor.
13. The method for preparing hexane from raffinate oil according to claim 1, characterized in that isohexane with mass concentration not less than 90%, and/or n-hexane with mass concentration not less than 60%, and/or cyclohexane with mass concentration not less than 99% is obtained in step (3) through separation.
14. The method for preparing hexane from raffinate oil according to claim 1, characterized in that isohexane with mass concentration not less than 99% and/or n-hexane with mass concentration not less than 80% and/or cyclohexane with mass concentration not less than 99.9% is obtained in step (3) through separation.
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CN110256190A (en) * 2019-06-20 2019-09-20 山东京博石油化工有限公司 A kind of production method of food-grade n-hexane
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