JP4812436B2 - Process for producing benzene and gasoline base from petrochemical raffinate - Google Patents

Description

  The present invention relates to a method for producing benzene and a gasoline base material using petrochemical raffinate as a raw material. More specifically, it produces high-quality, high-octane gasoline bases with increased octane numbers from petrochemical raffinates that have not been used effectively as gasoline bases because of its low octane number, and is useful as a petrochemical raw material. In other words, the present invention relates to a method for improving the quality of this petrified raffinate and achieving its effective use.

  With the internationalization of the oil industry, oil companies are promoting thorough efficiency and rationalization in the fields of refining, logistics, and sales in order to secure international competitiveness. On the other hand, in the automobile fuel field, suppression of exhaust gas from gasoline automobiles and cleanliness have become important issues, and automobile gasoline quality is required to have a low sulfur content and a low vapor pressure in order to cope with it. On the other hand, in the petrochemical field, surplus of by-products from olefin production equipment is expected due to changes in demand structure and supply-demand balance such as ethylene and propylene. In such a situation, among the by-products, the residue obtained by extracting aromatics from cracked oil, especially the petrochemical raffinate mainly consisting of C6 to C8 fractions, has low sulfur and low vapor pressure. Since the octane number is as low as 50 to 65, it has not been used effectively as a gasoline base material in the automobile fuel field. Also, in the petrochemical field, a part of this surplus petrochemical raffinate has been recycled as raw materials to olefin production equipment, but this recycling method has particularly naphthene content due to the composition as the raw material. Therefore, the yield of ethylene and propylene has been reduced, and another effective method for utilizing the petrochemical raffinate has been demanded from the viewpoint of the efficiency of the olefin production apparatus.

  Also, in the automotive fuel field, light hydrocarbons have been isomerized as a technology for improving the octane number of hydrocarbons with low octane number and obtaining high-quality hydrocarbons as gasoline base materials. There exists a method (for example, refer patent document 1). In this method, for example, a light fraction mainly composed of C5 to C6 normal paraffins such as desulfurized light naphtha from crude oil is isomerized by contacting with an isomerization catalyst, and its main component is C5 to C6 normal paraffin. It is a method aimed at increasing the octane number of the light fraction by converting the product into isoparaffins. However, even if this conventional method for isomerizing light hydrocarbons is applied to relatively heavy fossilized raffinate containing C7 to C8 paraffins and naphthenes, the C3 to C4 fraction is generated. In addition, polymerization or coking occurs, and the isomerization catalyst is deactivated, so that it is difficult to appropriately perform the desired isomerization, and it is difficult to increase the octane number of the petrified raffinate. Therefore, the high octane conversion of petrochemical raffinate has not been demonstrated yet.

  Conventionally, catalytic reforming of relatively heavy hydrocarbons is another technology that improves the octane number of hydrocarbons with a low octane number to obtain high-quality hydrocarbons as gasoline base materials. There is a way to do it. This process involves contacting a relatively heavy fraction consisting primarily of C6-C9 paraffins, naphthenes, and aromatics, such as desulfurized heavy naphtha from crude oil, with a reforming catalyst and its components. Is converted to an aromatic compound having a higher octane number to increase the octane number of the relatively heavy fraction.

Japanese Examined Patent Publication No. 6-29199

  Therefore, in view of the above-described conventional situation, the object of the present invention is to use petrochemical raffinate as a raw material in order to effectively use surplus petrochemical raffinate, and to use high-octane high-quality gasoline base material and petrochemical An object of the present invention is to provide a method for producing benzene having high utility as a raw material.

As a result of earnest research to achieve the above object, the present inventors have found that the above object can be achieved by the following production method, and have completed the present invention.
That is, the present invention is a catalytic reforming of a petrochemical raffinate having a boiling range of 60 to 180 ° C. and mainly comprising a C6 to C8 fraction obtained by removing an aromatic fraction from a cracked gasoline fraction obtained from an olefin production apparatus. A catalytic reforming process to obtain reformate by processing;
The reformed gasoline is divided into a light reforming fraction, a medium reforming fraction and a heavy reforming fraction, and the benzene concentration in the light reforming fraction is less than 3% by volume, and the heavy reforming fraction A distillation step A in which the concentration of benzene in the minute is less than 3% by volume ,
An aromatic extraction step of separating and obtaining the middle-quality reformed fraction obtained in the distillation step A into benzene and extraction residue;
A distillation step B for dividing the extraction residue into a light fraction and a heavy fraction so that the C7 fraction in the light fraction is less than 10% by volume ;
An isomerization step of isomerizing the light fraction obtained in the distillation step B;
Benzene from petrochemical raffinate and gasoline base material characterized in that it has a blending step for sequentially mixing the isomerization product obtained in the isomerization step and the heavy fraction obtained in the distillation step B. A manufacturing method is provided.

  That is, according to the present invention, benzene and a gasoline base material can be simultaneously and smoothly produced efficiently from a petrochemical raffinate having a low octane number and difficult to use as a gasoline base material. Benzene is highly useful as a petrochemical raw material, etc., and the gasoline base obtained by the present method is a high-quality gasoline base with a high octane number and low vapor pressure that can be suitably blended with automobile gasoline. Can be used.

  As the petrochemical raffinate used in the present invention, a by-product from an olefin production apparatus such as an ethylene production apparatus is used. In detail, in an olefin production apparatus, light naphtha is generally used as a raw material, and it is thermally decomposed to produce ethylene / propylene. At that time, a cracked gasoline fraction is by-produced. Since the by-product cracked gasoline fraction contains aromatic compounds such as benzene, toluene, xylene, etc., in the petrochemical industry, the aromatic component is extracted from the by-produced cracked gasoline fraction by an aromatic extractor. It is extracted with. This extracted aromatic component is effectively utilized as a petrochemical raw material. The residue fraction after the aromatic component is extracted from this by-produced cracked gasoline fraction is the petrochemical raffinate used as a raw material in the present application.

  The fossilized raffinate as a raw material to be treated in the present invention is a fraction rich in normal paraffins having a boiling range of 60 to 180 ° C. and mainly consisting of C6 to C8 fractions. The composition of the petrified raffinate used as a raw material in the present invention generally has a paraffin content of 20 to 85 vol%, a naphthene content of 15 to 65 vol%, an olefin content of 5 vol% or less, and an aromatic content of 10 vol% or less.

Hereinafter, exemplary embodiments of the present invention will be described specifically and in detail with reference to the drawings.
FIG. 1 is a process flow sheet conceptually showing an example of an embodiment of the present invention. In the embodiment shown in FIG. 1, the raw petrochemical raffinate is removed from the cracked gasoline fraction 1 by-produced in the olefin production apparatus, and the aromatic fraction 3 such as benzene, toluene, and xylene is removed by the aromatic extraction apparatus 2. And obtained as petrified raffinate 4 (aromatic extraction step A). This petrochemical raffinate 4 is processed by a catalytic reformer 5 to be a reformed gasoline 6 which is a high octane gasoline base (contact reforming process). This reformed gasoline 6 is lightly modified by a precision distillation device 7. It is divided into three fractions of a mass fraction 8, a medium reforming fraction 9, and a heavy reforming fraction 10 (distillation step A). The middle quality reformed fraction 9 divided and acquired by the precision distillation apparatus 7 is processed by the aromatic extraction apparatus 11, and then the benzene 12 is removed and acquired, and the extraction residue 13 is acquired (aromatics). Extraction step B). This extraction residue 13 is divided into two fractions of a light fraction 15 and a heavy fraction 16 by a precision distillation apparatus 14 (distillation step B), and the light fraction 15 is isomerized by an isomerization apparatus 17. Thus, an isomerized product which is a high octane gasoline base is obtained (isomerization step). The obtained isomerization product and the heavy fraction 16 obtained by the precision distillation apparatus 14 in the distillation step B are mixed in a blending step to isomerize the target low vapor pressure type high octane gasoline substrate. Gasoline 18 can be produced.

In the embodiment of FIG. 1, the following can be performed as required. That is, when the petrochemical raffinate 4 is subjected to the contact reforming treatment with the contact reforming device 5, desulfurized heavy naphtha can be mixed with the petrochemical raffinate 4 and the mixture can be subjected to the contact reforming treatment. At this time, the desulfurized heavy naphtha to be mixed is preferably a desulfurized heavy naphtha distilled from a crude oil atmospheric distillation apparatus. In particular, a suitable desulfurized heavy naphtha is a heavy naphtha having a boiling range of 70 to 180 ° C. Further, it is desirable that the sulfur content is 1 mass ppm or less, preferably 0.5 mass ppm or less. When the sulfur content is 1 mass ppm or less, there is no concern about the deterioration of the activity of the catalytic reforming catalyst. The mixing ratio of the petrified raffinate 4 and desulfurized heavy naphtha can be arbitrarily set as appropriate. By mixing desulfurized heavy naphtha, the production amount of benzene can be controlled, and if the mixing ratio is increased, the production ratio of benzene can be reduced.
Further, when the light fraction 15 obtained by dividing the extraction residue 13 by the precision distillation apparatus 14 is isomerized by the isomerization apparatus 17, desulfurized light naphtha is mixed with the light fraction 15 and the mixture is isomerized. Can be processed. In this case, the desulfurized light naphtha to be mixed is preferably one obtained by subjecting light naphtha distilled from a crude oil atmospheric distillation device to desulfurization treatment. In particular, a suitable desulfurized light naphtha is a light naphtha having a boiling range of 25 to 110 ° C, preferably 25 to 90 ° C. Moreover, it is preferable that a sulfur content is 1 mass ppm or less, Preferably it is 0.5 mass ppm or less. When the sulfur content is 1 mass ppm or less, there is little concern about the activity deterioration of the isomerization catalyst. The mixing ratio of the light fraction 15 of the extraction residue 13 and the desulfurized light naphtha can be arbitrarily set as appropriate. By mixing desulfurized light naphtha, the vapor pressure of the isomerized product can be adjusted, and consequently the vapor pressure of the target isomerized gasoline 18 can be adjusted. The vapor pressure of the isomerized product and thus the desired isomerized gasoline 18 is increased.
In addition, if the desulfurized heavy naphtha is mixed with the petrochemical raffinate 4 and subjected to catalytic reforming, and the light fraction 15 of the extraction residue 13 is mixed with desulfurized light naphtha and subjected to isomerization, further isomerization is performed. The property of gasoline can be improved.

Hereinafter, each process will be described in detail.
(Olefin production equipment)
The olefin production apparatus referred to in the present invention is an apparatus for producing olefins such as ethylene and propylene by thermal decomposition reaction using naphtha, ethane, LPG, NGL, gas oil and the like as a raw material. A method combining pyrolysis and cryogenic separation may be mentioned.
The olefin production raw material is heated and decomposed in a heating furnace, and then rapidly cooled to produce ethylene, propylene, butene, butadiene, cracked gasoline and the like. The cracked gasoline produced and by-produced here generally has a boiling range of 60 to 180 ° C. and is mainly composed of C6 to C8 components.

(Aromatic extraction step A)
The aromatic extraction step (referred to as aromatic extraction step A) used to obtain the petrochemical raffinate used as a raw material in the present invention is an aromatic such as benzene, toluene, xylene, etc. in cracked gasoline by-produced from the olefin production apparatus. This is a step of extracting and removing the minutes. In this aromatic extraction step A, the aromatic content in the petrified raffinate is preferably 10% by volume, preferably 5% by volume or less.
The aromatic extraction device referred to here may be an extraction device that is used industrially, and examples thereof include a liquid-liquid extraction method and an extractive distillation method.
The liquid-liquid extraction method is a method for selectively extracting aromatics by utilizing the difference in solubility in aromatic solvents and non-aromatic polar solvents. As this liquid-liquid extraction method, sulfolane using sulfolane is used. Method, Udex method combining glycol solvents, DMSO method using dimethyl sulfoxide, Morphylex and Formex method using N-formyl-morpholine, Aromex method using diglycolamine, TETRA method using tetraethylene glycol, Caroma method is mentioned.
The extractive distillation method is a method of separating aromatics by increasing the relative volatility of aromatics using a polar substance having a high boiling point, and this extractive distillation method includes N-methyl-2- Examples include the Distapex method using pyrrolidone, the Morphylane method using N-formyl-morpholine, and the GT-BTX method using a plurality of solvents.

  The petrified raffinate, which is an extraction residue from which aromatic components have been removed by the aromatic extraction apparatus in the aromatic extraction step A, generally has a boiling range of 60 to 180 ° C. and is rich in normal paraffins mainly composed of C6 to C8 fractions. It is a fraction that The composition of the petrified raffinate used as a raw material in the present invention is generally 20 to 85% by volume of paraffin, 15 to 65% by volume of naphthene, 5% by volume or less of olefin, and 10% by volume or less of aromatic. The weight ratio of methylcyclohexane and cyclohexane is preferably in the range of 1.0 to 7.0, more preferably 1.0 to 5.5.

(Contact reforming process)
In the present invention, the petrochemical raffinate obtained in the aromatic extraction step A is introduced as a raw material into the catalytic reforming device in the catalytic reforming step, and used for the catalytic reforming treatment. The catalytic reformer mentioned here is an apparatus for producing reformed gasoline using conventional heavy naphtha as a raw material, and includes a fixed bed semi-regenerative type, a cyclic type, a continuous regenerative type and the like.
In general, the catalyst used in the catalytic reforming reaction is a platinum / alumina-based catalyst containing 0.2 to 0.8% platinum. The catalyst may contain rhenium, germanium, tin, iridium or the like as the second component.

The general catalytic reforming reaction conditions for the fixed bed semi-regenerative type are preferably as follows.
Reaction temperature: 470-540 ° C.
Reaction pressure: 350-3500 kPa,
Hydrogen / hydrocarbon ratio: 3-10 mol / mol,
Space velocity (LHSV): 1-4 / h
If the reaction temperature is 470 ° C. or higher, a product oil having a high octane number is obtained. If the reaction temperature is 540 ° C. or lower, hydrocracking proceeds and the liquid yield decreases, and the catalytic activity decreases due to the formation of coke. Can be suppressed. If reaction pressure is 350 kPa or more, it can suppress that a coke produces | generates.
In the continuous regeneration system, the following conditions are preferable.
Reaction temperature: 510-530 ° C.
Reaction pressure: 350 to 1000 kPa,
Hydrogen / hydrocarbon ratio: 0.9 to 3.5 mol / mol,
LHSV: 1-4 / h
If the reaction temperature is 510 ° C. or higher, a product oil having a high octane number is obtained. If the reaction temperature is 530 ° C. or lower, hydrocracking proceeds and the liquid yield decreases, and the catalytic activity decreases due to the production of coke. Can be suppressed. If reaction pressure is 350 kPa or more, it can suppress that a coke produces | generates.

(Distillation step A)
The reformed gasoline obtained in the catalytic reforming step is separated into three fractions of a light reforming fraction, a medium reforming fraction and a heavy reforming fraction in the distillation step A. The separation of the three fractions can be performed using a conventional distillation column. For example, a two-stage combination method of a precision distillation column or a stripper is preferable. The reformed gasoline is separated so that the benzene concentration in the light fraction is less than 3% by volume, preferably less than 1% by volume, and the benzene concentration in the heavy reformed fraction is less than 3% by volume. It is desirable to carry out the distillation cut so that it is preferably less than 1% by volume, more preferably less than 0.5% by volume.
The medium reformed fraction separated in this distillation step A is used for the next aromatic extraction step B, and the light reformed fraction and the heavy reformed fraction are appropriately used as a gasoline base material or the like. Can do. Making the benzene concentration in the light reforming fraction and the benzene concentration in the heavy reforming fraction less than 3% by volume means that the concentration of benzene in the product gasoline when these fractions are blended as a gasoline base material. It is preferable from the viewpoint of suppressing exceeding 1% by volume and improving the benzene recovery rate in the method of the present invention.

  The reformed gasoline is generally distilled at a pressure of 0.01 to 2 MPa, preferably 0.05 to 1 MPa, and the number of theoretical columns of the distillation column is 10 to 150, preferably 30 to 100. . The reflux ratio represented by the ratio between the liquid flow rate in the column and the charged raw material flow rate is preferably 1-20, more preferably 1-10. For distillation, it is also possible to combine two distillation towers and separate the light reforming fraction in the first tower into the middle reforming fraction and the heavy reforming fraction in the second tower. . In addition, it is desirable to control the separation of the light reforming fraction, the medium reforming fraction, and the heavy reforming fraction of the reformed gasoline by the benzene concentration.

(Aromatic extraction process B)
In the middle reformed fraction of the reformed gasoline obtained in the distillation step A, benzene is separated by the aromatic extraction method in the aromatic extraction step. As the method for extracting benzene, the same method as in the aromatic extraction step A can be used. The separated benzene is obtained as one of the objects.
The extraction residue after separation and removal of benzene in this aromatic extraction step B is generally a fraction having a boiling range of about 60 to 100 ° C. and rich in normal paraffins mainly composed of C6 to C7 fractions. is there. The composition of the extraction residue is generally 80 to 100% by volume of paraffin, 5% by volume or less of naphthene, 5% by volume or less of olefin, and 10% by volume or less of aromatics.

(Distillation process B)
The extraction residue obtained in the aromatic extraction step B is further separated into a light fraction and a heavy fraction. This separation can be performed using a conventional distillation column. As the distillation column, a precision distillation column is preferable. The separation of the extraction residue is desirably carried out by distillation cutting so that the C7 fraction in the light fraction is less than 10% by volume, preferably less than 7% by volume, more preferably less than 3% by volume.
The distillation of the separation of the extraction residue is generally performed at a pressure of 0.1 to 2 MPa, preferably 0.2 to 1 MPa, and the theoretical number of distillation columns is 10 to 100, preferably 30 to 70. . The reflux ratio represented by the ratio between the liquid flow rate in the column and the charged raw material flow rate is preferably 1-20, more preferably 1-10.

The light fraction of the extraction residue is preferably cut between the boiling points of methylcyclopentane (boiling point 71.8 ° C.) and 2,2-dimethylpentane (boiling point 79.2 ° C.). This is because, in the subsequent isomerization step, if the C7 content is large, coke deposition on the catalyst used in the isomerization reaction and a decrease in the liquid yield are caused, so that it is suppressed. Therefore, although preferable cut temperature is based also on precision distillation conditions, it is 70-80 degreeC.
In the cut of the light fraction as described above, C5 naphthene and C6 naphthene are contained in the light fraction, but the total amount of C5 naphthene and C6 naphthene in the light fraction is generally 5% by volume or less. become.

(Isomerization process)
The light fraction of the extraction residue separated in the distillation step B is introduced into an isomerization apparatus and isomerized. In general, the isomerization reaction conditions are preferably as follows.
Isomerization reaction conditions Reaction temperature: 140-250 ° C, preferably 150-220 ° C
Reaction pressure: 1-5 MPa, preferably 2-4 MPa
Hydrogen / hydrocarbon ratio: 1-4 mol / mol, preferably 1.5-3 mol / mol
Space velocity (WHSV): 0.1 to 5 / h, preferably 0.5 to 2 / h

  A reaction temperature higher than 140 ° C. is preferable because it can prevent the catalyst life of the isomerization catalyst from being shortened. Moreover, it is preferable to make it 250 degrees C or less, since decomposition | disassembly of a light fraction advances and it can prevent that a liquid yield falls. Moreover, it is preferable that the water content in the raw material hydrocarbon before isomerization is 30 mass ppm or less because the decrease in the activity of the catalyst is not increased.

(Isomerization reaction catalyst used in the isomerization process)
In the isomerization step of the present invention, various isomerization reaction catalysts can be appropriately used as the isomerization reaction catalyst. However, solid superacid catalysts such as Pt / SO ₄ / ZrO ₂ solid superacid catalysts are used. Preferably used. The solid superacid catalyst mentioned here has the property of an acid stronger than 100% sulfuric acid, which is defined as a superstrong acid, and the skeletal isomerization reaction of paraffins at low temperature, which is advantageous in terms of thermodynamic equilibrium, proceeds even at room temperature. A catalyst supporting a super strong acid having such a property as to have an acid strength of 100% sulfuric acid or higher, and usually 100% sulfuric acid H ₀ = -11.93 or lower in terms of Hammett acidity function. A solid catalyst. For example, a catalyst supporting a compound having super strong acidity such as SbF ₅ or BF ₃ , a catalyst obtained by treating an oxide such as ZrO ₂ or Fe ₂ O ₃ with sulfuric acid, a fluorinated sulfonic acid resin or the like An example of a strong acid catalyst can be given.

  The composition of the solid super strong acid catalyst comprises a group consisting of at least one metal hydroxide or oxide selected from the group IV or group III of the short period periodic table, Containing at least one metal selected from Group VIIA, Group VIA, and Group IB (hereinafter referred to as “specific metal”) and sulfate radical or sulfate radical precursor, and firing and stabilizing. It is. Here, any of the specific metals or metal compounds can be supported on the carrier by a usual impregnation method, ion exchange method or the like. Preferred specific examples of the specific metal include nickel, ruthenium, rhodium, palladium, platinum, iron, manganese, chromium, silver, and copper. As for content of a specific metal, 0.01-10 mass parts is preferable with respect to 100 mass parts of support | carriers. The reason for this is that if 0.01 parts by mass or more, the catalytic activity effect of the metal is small and the stability of the catalytic activity can be prevented from becoming insufficient, and if it is within 10 parts by mass, the acid strength This is because it is possible to prevent the decrease in the isomerization rate and the isomerization rate in the isomerization reaction. Examples of sulfate radicals include, for example, 0.005 to 5 mol / liter, preferably 0.05 to 2.5 mol / liter sulfuric acid, 0.1 to 10 mol / liter ammonium sulfate, and the like. For example, substances that produce sulfate radicals after catalytic calcination treatment such as hydrogen sulfide and sulfurous acid gas can be used.

  Among the solid superacid catalysts, more preferred solid superacid catalysts are hydroxides or oxides of at least one element selected from silicon, titanium, zirconium, and tin, and hydroxides or oxides of aluminum. A carrier composed of at least one selected from the group consisting of at least one metal selected from nickel, ruthenium, rhodium, palladium, and platinum as a specific metal and a sulfate radical or a precursor of sulfate radical is fired and stabilized. It is a catalyst formed. An even more preferred solid superacid catalyst is a catalyst in which the support is a hydroxide or oxide of zirconium and the specific metal is platinum.

  The method for preparing the solid superacid catalyst used in the isomerization step of the present invention is not particularly limited. That is, the method for supporting the specific metal and the sulfate radical may be performed by any method. For example, after introducing the specific metal onto the carrier, the treatment with a treatment agent containing a sulfate radical is performed, and the firing stabilization. By doing so, a solid superacid catalyst can be prepared. Taking platinum as an example of the specific metal, it can be supported by immersing the carrier in an aqueous solution of chloroplatinic acid, tetraammineplatinum complex or the like, and after the carrying, treatment with a sulfate group-containing treatment agent or the like is performed. In that case, generally as a treating agent containing a sulfate group, 0.005 to 5 mol / liter, preferably 0.05 to 2.5 mol / liter sulfuric acid, 0.1 to 10 mol / liter ammonium sulfate, etc. Use 1 to 10 times the amount of catalyst mass. In addition, the same effect can be obtained by using a treatment agent that generates sulfate radicals after catalyst firing treatment such as hydrogen sulfide and sulfurous acid gas. In addition, after the treatment with a sulfate group-containing treatment agent or the like, a firing stabilization treatment is performed for 0.5 to 10 hours in an oxidizing atmosphere at a temperature of 450 to 800 ° C., preferably 500 to 700 ° C. By the above treatment, a solid super strong acid catalyst showing strong acidity can be obtained as an isomerization reaction catalyst. In addition, the catalyst firing stabilization treatment is performed in an oxidizing atmosphere because the catalytic activity decreases on the specific metal or the compound of the specific metal due to a change in the binding state of sulfate radical or a phenomenon such as reductive decomposition. It is for preventing.

  Prior to use in the isomerization reaction, the solid super strong acid catalyst is preferably subjected to pretreatment for stabilization of its catalytic activity, that is, reduction of the supported metal compound to metal and activation of strong acid sites. The pretreatment is performed under normal pretreatment conditions for a solid superacid catalyst. For example, the solid superacid catalyst is dried by maintaining it at a temperature of 100 to 500 ° C. for 1 to 5 hours, and then reduced at a temperature of 100 to 400 ° C. You can do it by doing.

(Blend process)
The isomerization product obtained by isomerizing the light fraction of the extraction residue in the isomerization step and the heavy fraction of the extraction residue obtained in the distillation step B (distillation step of the extraction residue). By blending, a high quality gasoline base material with a desired low vapor pressure and high octane number can be obtained.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

Example 1
According to the flow shown in FIG. 1, benzene and a gasoline base material were produced by using the fossilized raffinate having the properties shown in Table 1 as follows. The petrochemical raffinate is a residue obtained by extracting sulfolane from a cracked gasoline fraction obtained from an olefin production apparatus.

(Contact reforming treatment)
The catalytic reforming treatment of the petrochemical raffinate was performed in a bench plant having a catalyst filling amount of 5 ml. The catalyst used for the catalytic reforming reaction is a commercially available Pt / alumina catalyst. Before introducing the raw material, an in-situ reduction treatment was performed as a pretreatment. The reduction was carried out at a hydrogen flow rate of 8 L / H and 500 ° C. for 3 hours to activate the catalyst. After the pretreatment, a catalytic reforming treatment was performed under the reaction conditions shown below.
Catalytic reforming treatment conditions (fixed bed flow type)
Reaction temperature 510 ° C
Hydrogen partial pressure 0.7 MPa
Hydrogen / hydrocarbon ratio 5 mol / mol
Space velocity (LHSV) 2.0L / H
Table 2 shows the results of the catalytic reforming treatment of the petrochemical raffinate (properties of the reformed gasoline).

(Distillation step A)
The reformed gasoline obtained by the catalytic reforming treatment was divided into three fractions by a precision distillation apparatus. The amount of the light fraction extracted during precision distillation was matched to the temperature at the top of the distillation column, and the distillation was carried out so that the benzene concentrations in the light fraction and the heavy fraction were each 1% by volume or less. The distillation conditions at that time are shown below.
Distillation conditions Type Oldershaw type Theoretical plate number 70 plate Reflux ratio 5
Processing volume 10L

  The reformed gasoline was divided by precision distillation to obtain a light reformed fraction, a medium reformed fraction, and a heavy reformed fraction. Table 3 shows the properties and recovery rates of the obtained fractions. The yield of each fraction was 19.3 vol% for the light reforming fraction, 59.2 vol% for the medium reforming fraction, and 21.5 vol% for the heavy reforming fraction.

  As a result, it was found that 59.2% by volume of the middle reformed fraction containing benzene was obtained, and that the benzene content in the middle reformed fraction was obtained at a high concentration of 43.8% by volume. . Moreover, the octane number of the light reforming fraction was 82.7 and the octane number of the heavy reforming fraction was as high as 113.5, and it was found that these fractions could be used as a gasoline base material.

(Aromatic extraction process B)
Next, the middle reformed fraction obtained by dividing the reformed gasoline into three was subjected to aromatic extraction treatment to obtain benzene and extraction residue.
The aromatic extraction operation was performed by mixing equal amounts of sulfolane and a medium reforming fraction at room temperature, performing liquid-liquid extraction at room temperature, and extracting benzene in the medium reforming fraction.
The results are shown in Table 4.

  As a result, it was found that benzene was obtained with a high efficiency of 43.3% by this extraction operation.

(Distillation process B)
Furthermore, the obtained extraction residue was operated as follows.
First, the extraction residue having the properties shown in Table 4 was subjected to precision distillation using an Oldershaw type distillation apparatus, and was divided into a light fraction and a heavy fraction. The amount of the light fraction extracted during precision distillation was adjusted to match the temperature at the top of the distillation column, and distillation was performed so that the C7 heavy fraction in the light fraction was 1% by volume or less. The distillation conditions at that time are shown below.
The calculated octane number in Table 4 is an integrated value of values obtained by multiplying the octane number specific to each component in the produced oil (C5 or higher) by the volume ratio.
Distillation conditions Type Oldershaw type Theoretical plate number 50 plate Reflux ratio 5
Processing volume 10L
Table 5 shows the properties and recovery rates of the light and heavy fractions divided by precision distillation. The yield of the light fraction was 94.3% by volume, the yield of the heavy fraction was 4.5% by volume, and the recovery rate was 98.8% by volume. Moreover, the octane numbers of the respective fractions were 64.6 and 66.1.

(Isomerization process)
Next, isomerization of the light fraction of the extraction residue obtained by the distillation operation was performed in a bench plant having a catalyst filling amount of 7 ml. The catalyst used in the isomerization reaction was a Pt / SO ₄ / ZrO ₂ -based catalyst, and an in-situ reduction treatment was performed as a catalyst pretreatment before introducing the isomerization raw material. The reduction conditions were a hydrogen flow rate of 9 L / H, a preliminary drying at 150 ° C. for 3 hours, and a treatment at 220 ° C. for 14 hours to activate the catalyst. After the pretreatment, an isomerization treatment was carried out under the reaction conditions shown below.
In addition, the water | moisture content in the raw material hydrocarbon in this reaction was 10 mass ppm or less.
Isomerization conditions Reaction temperature 180 ° C
Hydrogen partial pressure 3.1 MPa
Hydrogen / hydrocarbon ratio 2 mol / mol
Space velocity (WHSV) 1.5 / h
Table 6 shows the results of isomerization treatment of the light fraction of the extraction residue (properties of the isomerized product). As a result of the isomerization reaction, the resulting oil obtained had an octane number of 73.4, and the liquid yield (at least C5 fraction) was 96.1% by volume.

Next, the light fraction of the extraction residue (isomerization product) subjected to the above isomerization treatment and the heavy fraction of the extraction residue obtained by precision distillation are blended to obtain a high target vapor with a low vapor pressure. An isomerized gasoline, which is a high-quality gasoline base material with octane number, was obtained. Table 7 shows properties, liquid yield, and the like of the obtained isomerized gasoline.
As a result, the octane number of isomerized gasoline is 73.4, which is about 9 higher than the octane number 64.6 of the light fraction of the extraction residue, and the vapor pressure is 46.9 kPa, which is a low vapor pressure. I understood.
It was also found that the increase ratio of octane number (product of liquid yield and octane number) increased by 564.

  From the above results, the petrochemical raffinate obtained from the olefin production apparatus was subjected to catalytic reforming treatment, and the reformed gasoline obtained in the catalytic reforming step was divided into three fractions by distillation, and divided by the distillation. The middle reformed fraction is subjected to aromatic extraction treatment to obtain benzene, the extraction residue obtained in the extraction step is further divided into two by distillation, and the light fraction obtained by the distillation is isomerized. Thus, benzene can be obtained in a high yield. Further, as a high octane gasoline base material, in addition to isomerized gasoline having a high octane number at a low vapor pressure as a main purpose, the light reformed fraction and heavy oil are separated by distillation step A. A quality reforming fraction can also be obtained.

It is a process flow sheet which shows an example of an embodiment of the present invention notionally.

Explanation of symbols

1: cracked gasoline fraction 2: aromatic extractor 3: aromatic fraction 4: petrochemical raffinate 5: catalytic reformer 6: reformed gasoline 7: precision distillation device 8: light reformed fraction 9: medium quality reform Mass fraction 10: Heavy reformed fraction 11: Aromatic extractor 12: Benzene 13: Extraction residue 14: Precision distillation device 15: Light fraction 16: Heavy fraction 17: Isomer 18: Isomerized gasoline

Claims (1)

A reformed gasoline obtained by catalytically reforming a petrochemical raffinate obtained by removing an aromatic fraction from a cracked gasoline fraction obtained from an olefin production apparatus and having a boiling range of 60 to 180 ° C. and mainly comprising a C6 to C8 fraction. A catalytic reforming step to obtain
The reformed gasoline is divided into a light reforming fraction, a medium reforming fraction and a heavy reforming fraction, and the benzene concentration in the light reforming fraction is less than 3% by volume, and the heavy reforming fraction A distillation step A in which the concentration of benzene in the minute is less than 3% by volume ,
An aromatic extraction step of separating and obtaining the middle-quality reformed fraction obtained in the distillation step A into benzene and extraction residue;
A distillation step B for dividing the extraction residue into a light fraction and a heavy fraction so that the C7 fraction in the light fraction is less than 10% by volume ;
An isomerization step of isomerizing the light fraction obtained in the distillation step B;
Benzene from petrochemical raffinate and gasoline base material characterized in that it has a blending step for sequentially mixing the isomerization product obtained in the isomerization step and the heavy fraction obtained in the distillation step B. Production method.

Images