JPH1180751A - Production method of non-carcinogenic aromatic hydrocarbon oil by solvent extraction method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a non-carcinogenic, safe and environmentally-friendly, non-carcinogenic polycyclic aromatic compound-free compound that has the same performance as conventionally used rubber process oils. Provided is a method for producing a petroleum-based aromatic hydrocarbon oil that does not pollute. A solvent extraction operation for selectively extracting and removing a polycyclic aromatic compound in a first stage from a petroleum-based hydrocarbon mixture by first extracting and removing an aromatic carbon content of 12% or more and a polycyclic aromatic compound content An extraction residue of less than 1.6% is obtained, and the extraction residue is further subjected to an extraction treatment in the second stage of extraction operation to obtain an aromatic carbon content of 26% or more and a polycyclic aromatic compound content of 3%. Less than aromatic hydrocarbon oil is obtained as the extraction oil. [Effect] The aromatic hydrocarbon oil thus obtained has the same performance as that of a conventionally used rubber process oil and has non-carcinogenic safety. Suitable for product manufacturing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing a substantially non-carcinogenic aromatic hydrocarbon oil containing substantially no polycyclic aromatic compounds. In particular, the present invention relates to a method for producing a petroleum-based aromatic hydrocarbon oil used in the production of rubber, ink products, and the like, and relates to a substantially non-carcinogenic aromatic hydrocarbon oil containing almost no polycyclic aromatic compound. Related to the production method.

[0002]

2. Description of the Related Art Generally, a petroleum-based aromatic hydrocarbon oil has a boiling point range of from 260 to 260 obtained by vacuum distillation in the refining of crude oil.
In the solvent extraction purification method of a lubricating oil production fraction at 650 ° C.,
It is well known to those skilled in the art that it is produced as a fraction rich in aromatic hydrocarbon compounds. Therefore, although petroleum-based aromatic hydrocarbon oils differ in their properties and chemical composition depending on the type of crude oil and the conditions of the extraction and refining method, they basically contain a considerable amount of aromatic hydrocarbon compounds as constituent components. Features.

It is well known to those skilled in the art that this petroleum-based aromatic hydrocarbon oil is usefully used as a processing oil for rubber such as natural rubber or SBR used for tires and the like, and as an extension oil for raw SBR. ing. That is, these petroleum-based aromatic hydrocarbon oils utilize the compatibility with the rubber to improve a series of workability in rubber processing and improve physical properties of a final rubber product after vulcanization. Has been added for.

[0004] In order to exhibit compatibility with the rubber, these petroleum-based aromatic hydrocarbon oils are typically used in ASTM D 2140.
In the composition analysis method defined in the above, the carbon content (hereinafter, sometimes referred to as aromatic carbon content, sometimes referred to as Ca%) which forms an aromatic ring, which substantially means the aromatic compound content, is 27 to 55%. I have.

[0005]

However, these petroleum-based aromatic hydrocarbon oils contain, as an additional component, 15 to 28% of a polycyclic aromatic compound (hereinafter referred to as PCA) among the aromatic hydrocarbon compounds contained as components. (Polycyclic aromatics)
May be included). In recent years, according to the EU directive, petroleum products containing 3% or more of this polycyclic aromatic compound have been suggested to be carcinogenic, and efforts have been made worldwide to reduce the amount of polycyclic aromatic compounds in petroleum products.

[0006] Process oils and extender oils for rubber are no exception and many proposals have been made.
-50524 (GB2252978, US550413
5, EP575400), the viscosity is 32 to 50 cS.
t. The aromatic component is 30 to 55% by weight, the saturated hydrocarbon component is 40 to 65% by weight, and the polycyclic aromatic compound or PCA measured by the IP346 method is 30 to 55% by weight according to the clay-gel method specified in ASTM D 2007. Although a petroleum hydrocarbon oil of less than 3% is proposed, the aromatic carbon content (Ca%) specified in ASTM D2140 does not reach 26% in the range of aromatic components by the clay-gel method. , Because it cannot exhibit compatibility and affinity with rubber, it is unsuitable as a substitute for petroleum-based aromatic hydrocarbon oils that have been conventionally used, and especially for SBR and natural rubber. Was unusable at all.

[0007] Further, in EP04179801, an aromatic content of 50% by weight or more and an IP3
A process for producing a process oil for rubber having a PCA content of less than 3% from a petroleum-based lubricating oil fraction by a two-stage extraction method according to the 46th test method, that is, a fraction mainly rich in aromatic components in the first stage extraction ( (Including useful process oil fractions and PCA fractions), and extracting the extracted oil with PC in a second stage extraction
A method has been proposed in which the A fraction is extracted and removed to produce process oil as an extraction residue. This method is similar to the present invention, but differs fundamentally in the following points.

One is that according to this method, a useful process oil fraction and a P are extracted from a petroleum-based lubricating oil fraction in the first stage of extraction.
Both CA fractions must be extracted, requiring a corresponding amount of extraction solvent, and the mixture of the extracted oil and solvent obtained from the first extraction column before being provided to the second stage extraction column. ,
It is necessary to recover or adjust the contained solvent. This complicates the process and imposes extra costs.

Since the present invention is based on the method of extracting only PCA in the first step, only a small amount of extraction solvent is required in this step, and the extraction residual oil supplied to the second step contains a very small amount of extraction solvent. This is advantageous as a process in that no special solvent recovery or solvent amount adjustment is required.

According to the method of EP04179801, PCA is extracted and removed in the second stage of extraction. However, if the target oil is an oil which is already rich in aromatic compounds having similar polarities, The dissolution selectivity of PCA in the dissolution extraction will be reduced, which inevitably lowers the yield of useful process oils produced as extraction resid and increases process costs.

Since the present invention is a step of extracting PCA in the first stage, it does not hinder the dissolution selectivity of PCA, and it is technically advantageous to produce a process oil with a PCA of 3% or less in terms of cost.

[0012] In Japanese Patent Publication No. 7-501346,
Establish a unique relationship between mutagenicity indices and physical properties, and use the process conditions to extract non-carcinogenic bright stock extracts or deoiled oils from hydrocarbon atmospheric distillate resid feedstocks. Although a manufacturing method has been proposed, the present invention provides a EU of substantially less than 3% of PCA.
It is hard to say that the order has been reached.

[0013] In addition, DE 4038458 proposes a method based on a critical extraction method, and WO 9528458 proposes a method based on an air oxidation effect. Petroleum-based aromatic hydrocarbon oil that satisfies the performance and the carcinogenicity recommendation by the EU Directive, that is, PCA 3% or less at the same time, such as those that are not suitable for the replacement of process oils for rubber and that are too costly in terms of technology and process. No production method which is advantageous in terms of both technology and cost has been proposed. There is a strong demand for simple and economical production of non-carcinogenic petroleum aromatic hydrocarbon oils.

[0014]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a non-carcinogenic petroleum-based aromatic hydrocarbon oil having the same performance as that of a process oil for rubber, and a petroleum-based aromatic hydrocarbon oil containing PCA. It is to satisfy this requirement by providing a new manufacturing method.

In particular, it is an object of the present invention to provide a simple and economically advantageous non-carcinogenic petroleum aromatic hydrocarbon using a two-stage, individually designed extraction process from a petroleum hydrocarbon mixture. It is to provide a new method for producing hydrogen oil.

[0016]

Means for Solving the Problems Polycyclic aromatic hydrocarbons having the same performance as petroleum aromatic hydrocarbon oils conventionally used as rubber process oils and having carcinogenicity according to the IP346 test method. Novel and environmentally friendly new petroleum aromatic hydrocarbon oils with less than 3% compounds are produced through a strictly designed two-stage extraction process of the present invention.

The feedstock oil used in the present invention has a boiling point of 26 which is used for producing a conventional petroleum aromatic hydrocarbon oil.
The lubricating oil fraction after vacuum distillation at 0-650 ° C is applied.
Also, deasphalted oil from which asphalt substances have been removed from lightly distilled hydrocarbon residues such as propane can be suitably used as the feedstock oil of the present invention.

The present invention is accomplished by performing a strictly designed two-stage extraction operation using these feedstocks.

The solvent in the extraction operation of the present invention is furfural, phenol, or phenol, which selectively dissolves aromatic compounds.
A polar solvent such as n-methylpyrrolidone is applied. These solvents may be used alone or as a mixed solvent of two or more.

However, it is preferable to use the same solvent as the solvent used in the first step and the second step regardless of how these solvents are used. This is because the first-stage extraction residue is subjected to the second-stage extraction operation.
The process can be performed without any extra operation such as solvent recovery, which is advantageous in process cost.

First, in the first stage of the extraction step, the extraction operation is carried out under strictly selective extraction conditions for polycyclic aromatic compounds, ie, PCA. That is, a generally used countercurrent contact type extraction column can be used, the extraction temperature defined at the top and bottom of the column is controlled, and the flow rate of the solvent with respect to the raw material flow rate, that is, the solvent ratio is correlated with the extraction temperature. Is achieved by controlling

The top temperature is in the range of 45 to 70 ° C, more preferably 45 to 60 ° C.

The overhead temperature is an important factor which determines the solubility in the extraction operation and the polarity of the dissolved fraction, that is, the solubility in the solvent. PC of the extracted residual oil which is extremely reduced in the amount of dissolved aromatic compound and is supplied to the second stage by the IP346 test method
It becomes difficult to make the A value less than 1.6% by weight. 7
When the temperature exceeds 0 ° C., the dissolution amount of not only the polycyclic aromatic compound but also the aromatic compound increases, and the PCA value of the extracted residual oil supplied to the second stage by the IP346 test method is significantly reduced from 1.6% by weight. However, the amount of aromatic compounds contained is greatly reduced, and the aromatic carbon content becomes 12% or less, and it becomes difficult to produce useful process oil with high yield in the second stage extraction operation. Therefore, the top temperature is preferably in the range of 45 to 70 ° C, more preferably 45 to 60 ° C.

The bottom temperature is desirably in the range of 40 to 50 ° C. and must be lower than the top temperature. Using the difference between the bottom temperature and the top temperature, the internal reflux of the solute, that is, the one dissolved in the solvent at the top elutes at a lower temperature at the bottom of the solute, and the solute in the extraction operation by refluxing in the column It is an important factor in selectivity.

In this sense, it is advantageous to adopt a lower temperature for the bottom of the column and to take a large temperature gradient from the top of the column, but if the temperature gradient is too large, the internal reflux will be too large, and flooding and the like will occur. This is a problem because it causes the phenomenon described above and the extraction operation cannot be performed.

Although there is a difference depending on the structure of the extraction tower used, in a countercurrent contact type extraction tower, the feed oil is introduced into the tower from the bottom of the tower. However, when the feed temperature of the feedstock of the present invention is lower than 40 ° C., the flow viscosity of the feedstock increases, so that a large amount of power is required for pumping up and the contact efficiency in the extraction column is increased. In addition, the stirring power for the dispersion of the feedstock oil for increasing the oil content is increased, and the process cost is increased, which is a problem. On the other hand, if the temperature exceeds 50 ° C., the temperature difference from the top decreases, solute selectivity decreases, and PCA
It becomes difficult to make the value less than 1.6% by weight. Therefore, the bottom temperature is desirably in the range of 40 to 50 ° C., and must be lower than the top temperature.

The ratio of the flow rate of the solvent to the flow rate of the raw material is referred to as the solvent ratio, and is an important factor that determines the amount of extraction and dissolution together with the extraction temperature. That is, if the solvent ratio is large, not only the PCA fraction but also useful aromatic compounds are dissolved, and if the solvent ratio is too small, the target PCA fraction cannot be sufficiently extracted and removed.

The solvent ratio is preferably from 1.2 to 3.0. 3.
If it exceeds 0, not only the PCA fraction but also useful aromatic compounds will be dissolved, and the AST of the extracted residual oil to be supplied to the second stage extraction tower will be dissolved.
The carbon content forming an aromatic compound by the composition analysis method specified in MD2140 is 12% or less, and as a result, a useful aromatic hydrocarbon oil having an aromatic carbon content of 26% or more in the second stage extraction operation. Can not get. If it is less than 1.2, extraction and removal of the PCA fraction will not be sufficient, and the PCA content of the extraction residual oil supplied to the second-stage extraction tower will exceed 1.6%. PCA in extraction operation
A non-carcinogenic aromatic hydrocarbon oil having a content of less than 3% cannot be obtained.

More importantly, the solvent ratio is in the range of 1.2 to 3.0 in correlation with the raw material PCA content and the overhead temperature, that is, when the PCA content of the raw material oil is large, As the temperature at the top of the column is increased, the solvent ratio is increased within the range up to 3.0. On the other hand, when a feedstock with a low PCA content is supplied, the operating conditions are correlated in a direction in which the tower top temperature and the solvent ratio are reduced, and the PCA content of the obtained extracted resid is 1.6%.
The solvent ratio at which the aromatic carbon content is 12% or higher and the overhead temperature are controlled in a correlated manner.

Thus, as the extraction residual oil to be supplied to the second stage, an aromatic carbon content of 12% or more and a PCA content of less than 1.6% are obtained.

An aromatic carbon content of at least 12% in the extraction residue is an essential requirement for the present invention, and if it is less than 12%, a useful aromatic carbon content of 26% in the second stage extraction operation. The above aromatic hydrocarbon oil cannot be obtained.

A PCA content of less than 1.6% in this extraction residue is also an essential requirement, and if it is 1.6% or more, non-carcinogens having a PCA content of less than 3% in the second stage extraction operation. Aromatic hydrocarbon oil cannot be obtained.

More importantly, since this extraction residue contains only a very small amount of the solvent used in the first stage, the extraction residue used in the second stage must be subjected to extra processing such as solvent recovery and solvent amount adjustment. That is, it can be directly charged into the second extraction column without performing any operation. The advantage here is that the PCA fraction is first extracted and removed. In this sense, it is particularly preferable to use the same solvent for the first and second extraction columns.

In the second extraction step, a useful aromatic hydrocarbon oil is obtained in good yield with an aromatic carbon content of 26% or more and a PCA content of less than 3%. Aim.

In the second stage of the extraction column, the top temperature is 90 to
A range of 125 ° C. is preferred. The overhead temperature is related to the amount dissolved and the selectivity of the solute as in the extraction operation of the first stage.
In order to extract a larger amount of aromatic hydrocarbon oil in the extraction operation of the stage, the higher the temperature, the more desirable. However, when the temperature exceeds 125 ° C., the non-aromatic hydrocarbon compound is dissolved and extracted. However, it is difficult to obtain an extracted oil having an aromatic carbon content of 26% or more. When the temperature is lower than 90 ° C., the dissolution amount decreases, the yield of the extracted oil decreases, and the process cost increases. At the same time, the PCA content increases to 3% or more, and a non-carcinogenic aromatic hydrocarbon oil can be obtained. It becomes difficult.

The bottom temperature is calculated by utilizing the difference from the top temperature.
The internal reflux of the solute, ie, that dissolved in the solvent at the top of the column, elutes at a lower temperature at the bottom of the column, which is an important factor in the selectivity of the solute in the extraction operation by reflux in the column.

In this sense, it is advantageous to adopt a lower temperature for the bottom of the tower and to take a large temperature gradient with the top of the tower. However, if the temperature gradient is too large, the internal reflux will be too large and flooding etc. This causes a phenomenon that the extraction operation cannot be performed.

In the extraction operation of the second stage of the present invention, the extraction operation was most stably achieved when the temperature gradient from the top of the column was 30 to 40 ° C. Therefore, the bottom temperature is correlated with the top temperature, that is, 60 to 40 ° C. so that the temperature gradient is 30 to 40 ° C.
It is preferably applied in the range of 85 ° C.

The solvent ratio is preferably from 2.0 to 5.0. When the solvent ratio is less than 2.0, the amount of the aromatic compound dissolved decreases, the yield of the aromatic hydrocarbon oil is reduced, the process cost is increased, and at the same time, the non-carcinogenic fragrance having a PCA content of less than 3% is obtained. It is difficult to obtain group hydrocarbon oils. If the solvent ratio exceeds 5.0, it is difficult to dissolve and extract non-aromatic compounds to obtain a useful aromatic hydrocarbon oil having an aromatic carbon content of 26% or more. Cost is high, and this is a problem in terms of process cost.

The thus obtained petroleum aromatic hydrocarbon oil having an aromatic carbon content of 26% or more and a PCA content of less than 3% according to the present invention is compatible with conventionally used rubber process oils and ink compounding oils. It is a non-carcinogenic petroleum aromatic hydrocarbon oil that has the same performance and is safe and does not pollute the environment.

Particularly, when the aromatic carbon content is 26% or more,
%, The affinity and solubility with the rubber are insufficient, and the physical properties of the rubber product using the same, particularly, a decrease in tensile strength and a decrease in elongation are caused. This is an essential requirement for the aromatic hydrocarbon oil of the present invention.

Examples of the present invention will be described below. The invention will be more clearly illustrated and fully understood by the following examples of data obtained from operating conditions that exhibit more salient features of the invention, and data provided as comparative examples. However, the present invention is not limited to these examples.

[0043]

【Example】

[Table 1] Table 1 shows the properties of the feedstock oil used in the present invention. Degreasing oil used as a feedstock and lubricating oil fraction after vacuum distillation are:
It varies depending on the type of crude oil, the severity of the distillation refining method, or the conditions of the stripping operation, and its properties are not limited to these three, but are generally representative of them. The properties of the feedstock are as follows: JIS K 2249 (Crude oil and petroleum products-Density test method and density / mass / volume conversion table). Vibration density test method, viscosity is JIS K 2283 (crude oil and petroleum products-kinematic viscosity test method and viscosity index calculation method), refractive index is JIS C 2101
The aniline point was measured in accordance with JIS K2256 (Petroleum product aniline point and mixed aniline point test method) using a 14.4 Abbe refractometer of (Electrical insulating oil test method).

[0044]

[Table 2] Table 2 shows the results of the first stage extraction processing according to the present invention.
In Example 1, an extraction treatment was carried out by using deflaking oil as a raw material oil, furfural as a solvent, a tower top temperature of 60 ° C., a tower bottom temperature of 40 ° C., and a solvent ratio of 2.3 to obtain an aromatic carbon content (Ca). 1
An extraction oil with 5.0% and a PCA content of 0.6% was obtained.
In Example 2, a lubricating oil fraction A was used as a feed oil, furfural was used as a solvent, a tower top temperature was 55 ° C., a tower bottom temperature was 40 ° C., a solvent ratio was 1.8, and an aromatic carbon content (Ca) was obtained. ) 1
An extracted oil with a content of 7.0% and a PCA content of 1.4% was obtained.
In Example 3, a lubricating oil fraction B was used as a feed oil, phenol was used as a solvent, an extraction treatment was performed at a tower top temperature of 60 ° C., a tower bottom temperature of 45 ° C., and a solvent ratio of 2.8 to obtain an aromatic carbon content ( Ca) 1
An extracted oil with 3.0% and 1.2% PCA content was obtained.

[0045]

[Table 3] Table 3 shows the results of the first-stage extraction processing not according to the present invention. In Comparative Examples 1 to 3, the extraction conditions according to the present invention, that is, a solvent ratio of 1.2 to 3.0, a top temperature of 45 to 70 ° C., and a bottom temperature of 40 to 50 ° C. deviate from aromatics. A second stage extraction operation with an aromatic carbon content of 12% or more and a PCA content of less than 1.6%, even if either the carbon content is 12% or more or the PCA content is less than 1.6%. Cannot obtain the intermediate oil to be supplied.

[0046]

[Table 4] Table 4 shows the results of the second stage extraction operation according to the present invention.
In Example 4, as a result of performing an extraction treatment at a tower top temperature of 121 ° C., a tower bottom temperature of 82 ° C., and a solvent ratio of 3.2 using the extraction residual oil obtained in Example 1, the aromatic carbon content was 34. An aromatic hydrocarbon oil having a content of 0.5% and a PCA content of 2.4% was obtained. In Example 5, the extraction residual oil obtained in Example 2 was used, and the top temperature was 115 ° C., the bottom temperature was 78 ° C., and the solvent ratio was 2.8.
As a result of performing the extraction treatment, the aromatic carbon content was 37.0%.
Thus, an aromatic hydrocarbon oil having a PCA content of 2.8% was obtained. In Example 6, the extraction residual oil obtained in Example 3 was subjected to an extraction treatment at a tower top temperature of 96 ° C., a tower bottom temperature of 64 ° C., and a solvent ratio of 4.5.
An aromatic hydrocarbon oil having 5.5% and a PCA content of 2.9% was obtained.

[0047]

[Table 5] Table 5 shows the results of the second stage extraction operation not according to the invention. Comparative Examples 4 to 6 show the results of using the intermediate oil obtained by the extraction operation according to the present invention as a raw material and applying the conditions of the extraction operation under conditions not according to the present invention. The results show that, even when the extraction resid according to the present invention is used as a raw material, the conditions of the second stage extraction operation according to the present invention, ie, the solvent ratio is 2.0 to 5.0, the tower top temperature is 90 to 125 ° C, and the tower bottom temperature is 60 to 85. When the temperature is out of the range, a non-carcinogenic useful aromatic hydrocarbon oil having an aromatic carbon content of 26% or more and a PCA content of less than 3% cannot be obtained. Comparative Examples 7 to 9 use the intermediate oil obtained by the extraction operation not according to the present invention as a raw material,
The result of applying the conditions of the stage extraction operation under the conditions of the present invention is shown. The results show that, if the extraction residual oil not according to the present invention is used as a raw material, the conditions of the second-stage extraction operation according to the present invention, ie, the solvent ratio is 2.0 to 5.0, the top temperature is 90 to 125 ° C., and the bottom temperature is 6
Even when the range of 0 to 85 ° C. is applied, the aromatic carbon content 26
% Indicates that a non-carcinogenic useful aromatic hydrocarbon oil having a PCA content of less than 3% and a PCA content of less than 3% cannot be obtained.

[0048]

[Table 6]

[Table 7] Table 6 shows the results of studying the aromatic hydrocarbon oil obtained by the present invention as a process oil for rubber. Table 7 shows the results of studies on aromatic hydrocarbon oils not according to the present invention and conventionally used process oils for aromatic rubbers.

The rubber compound used in the study is JIS K 6383 (test method for synthetic rubber SBR) used in the study of compounding materials such as raw rubber, carbon black and process oil.
No. in the standard recipe No. A compounding system according to the compounding method for non-oiled rubber of No. 1 was used, and a kneading method using a rubber compounding roll was also performed by the method described in the same test method. The vulcanization conditions were determined from the results measured with a Japan Synthetic Rubber Curastometer, and vulcanized with a press vulcanizer. For the measurement of product properties, hardness is JIS K 6301 (vulcanized rubber physical test method), tensile strength and 300% tensile stress and elongation are JIS.
K 6251 (Tensile test method for vulcanized rubber), tear strength is JIS
K 6252 (Tear test method for vulcanized rubber) and oil bleedability were carried out by visual inspection after standing at room temperature for 48 hours.

Examples 7 and 8 are the results of investigations on the aromatic hydrocarbon oil according to the present invention, and it was confirmed that they exhibited product properties comparable to those of the commercially available process oil of Comparative Example 10. . Comparative Example 11 is a study result of a hydrocarbon oil not according to the present invention. Compared with the result of the commercially available process oil of Comparative Example 10, the tensile strength and elongation are extremely poor,
Oil bleed was observed in 20 parts of the process oil, and it was confirmed that the oil was not usable.

[0051]

Since the present invention is configured as described above, it has the following effects.
The present invention provides a non-carcinogenic petroleum-based aromatic hydrocarbon having the same performance as a petroleum-based aromatic hydrocarbon oil containing a carcinogenic polycyclic aromatic compound conventionally used as a rubber process oil. Hydrogen oil is converted from petroleum hydrocarbon mixture to 2
By strictly designed solvent extraction method of each step,
A simple and economically advantageous method of manufacture is provided.

[0052]

[Brief description of the drawings]

FIG. 1 is a process chart according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 First-stage extraction tower solvent line 2 First-stage extraction tower feed oil line 3 First-stage extraction tower extraction residual oil line 4 First-stage extraction tower extraction oil 5 Second-stage extraction tower solvent line 6 Second-stage extraction tower extraction Residual oil 7 Second-stage extraction tower extraction oil line 8 Recovery solvent 9 Aromatic hydrocarbon oil 10 Heat exchanger 11 First-stage extraction tower 12 Second-stage extraction tower 13 Solvent recovery tower

Claims (6)

[Claims] 1. A petroleum hydrocarbon mixture which is firstly subjected to a solvent extraction in the first stage by a composition analysis method specified in ASTM D 2140. Aromatic compound content
An extract residue of less than 6% is obtained, and the extract residue is further subjected to a second stage solvent extraction to an ASTM D 2140 having an aromatic carbon content of 26% or more and a polycyclic aromatic compound content of 3 according to the IP346 test method. % Of non-carcinogenic petroleum aromatic hydrocarbon oil as an extraction oil. 2. The solvent used in the solvent extraction is a solvent selected from polar solvents of furfural, phenol, and n-methylpyrrolidone, or a mixed solvent of two or more solvents in both the first step and the second step; and A first step and a second step, wherein a common solvent is used.
The method described in the section. 3. The solvent extraction method of the first step uses a countercurrent contact type extraction column, a solvent ratio of 1.2 to 3.0, a top temperature of 45 to 70 ° C., and a bottom temperature of 40 ° C. The method according to claim 1 or 2, wherein the method is carried out at a temperature in the range of -50 ° C. 4. The solvent extraction method of the second stage uses a countercurrent contact type extraction column at a solvent ratio of 2.0 to 5.0, a top temperature of 90 to 125 ° C. and a bottom temperature of 60 ° C. The method according to any one of claims 1 to 3, characterized in that the method is carried out at a temperature in the range of -85 ° C. 5. A petroleum hydrocarbon mixture having a boiling point range of 26.
5. The method according to claim 1, wherein the fraction is a fraction used for producing a lubricating oil at 0 to 650 [deg.] C. 6. The method according to claim 1, wherein the petroleum hydrocarbon mixture is deoiled oil from vacuum distillation residue.
6. The method according to any one of items 2, 3, 4, and 5.