JP4213062B2 - Environmentally friendly clean gasoline and its manufacturing method - Google Patents

Description

  The present invention relates to gasoline with reduced environmental impact and a method for producing the same. In particular, the present invention relates to gasoline that has sufficient operating characteristics while reducing environmental impact by reducing sulfur content, aroma content, and the like and ensuring sufficient octane number.

  In recent years, there are concerns about the environmental impact of automobile fuels, and automobile fuels with low environmental impact are desired. It is known that the sulfur content in fuel oil for gasoline engines deteriorates the performance of the exhaust gas catalyst at the time of combustion, and there is an increasing demand to reduce it to 10 mass ppm or less, and further to 1 mass ppm or less. In addition, it has been pointed out that aroma (aromatic hydrocarbon) and olefin (unsaturated hydrocarbon) in gasoline may adversely affect the environment. On the other hand, in order to ensure the driving performance of an automobile using a gasoline engine, it is necessary to maintain a high octane number and appropriate distillation properties. As the high octane fuel base material, for example, a material rich in aroma (aromatic content, aromatic hydrocarbon content) is often used, and the amount of aromatic compounds in the exhaust gas increases.

  It is also desired to reduce the volatilization of low-boiling fractions in fuel, but simply reducing the low-boiling fraction in fuel causes a problem of causing deterioration in operating performance, particularly startability. . In addition, when the current fuel oil base material or manufacturing process is used and the sulfur content of gasoline fuel is 10 mass ppm or less, the operating performance of the product may be deteriorated depending on the properties of the base material used and the blend ratio. Sometimes.

  Therefore, instead of using aroma and olefin which are high octane components, it is necessary to produce a gasoline base material mainly composed of isoparaffin having a relatively high octane number. As a method for producing such a base material, an isomerization reaction or an alkylation reaction is known. For example, Patent Document 1 discloses a method for producing gasoline in which olefins and aromas are reduced and the isoparaffin ratio is increased. However, this method does not reach 50% even when the amount of isoparaffin is large, and the aroma content exceeds 20%. Patent Document 2 discloses a method for producing environmentally friendly gasoline with reduced olefins and aromas. However, this method contains 15 to 35% of aroma and was still insufficient for reducing aromatic hydrocarbons in the exhaust gas.

Japanese Patent Application 2000-336374 Special table 2003-501513

  Thus, conventionally, a gasoline that maintains operating performance such as octane number and at the same time sufficiently reduces sulfur content, aroma content, and the like, and a production method thereof have not been proposed. An object of the present invention is to provide a clean gasoline in which operation performance such as octane number is maintained in gasoline fuel and sulfur content, aroma content, etc. are sufficiently reduced, and a method for producing the same.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the intended clean gasoline can be produced by combining the isomerization step and the alkylation step, and have reached the present invention.

  That is, the method for producing an environmentally friendly clean gasoline according to the present invention includes (a) a fractionation step of fractionating a heavy fraction containing at least 120 to 170 ° C. boiling point component from a feedstock composed of hydrocarbon; Isomerization of the heavy fraction having an aroma content of 10% by volume or less into an isomerized heavy fraction, and (c) hydrocarbons having 3 and 4 carbon atoms generated in the isomerization step as raw materials. It comprises an alkylation step for producing an alkylate, and (d) a blending step for blending at least the isomerized heavy fraction and the alkylate into a clean gasoline.

  Preferably, (a) the feed oil in the fractionation step is a fluid catalytic cracking oil obtained from the petroleum refining step, and the fractionation step contains at least 40 ° C. to 70 ° C. boiling point component together with the heavy fraction. Separating a light fraction, and having a desulfurization step of removing thiol from the light fraction to obtain a desulfurized light fraction, (b) nuclear hydrogenation of the heavy fraction prior to isomerization It has a hydrogenation process of hydrotreating under conditions where the reaction proceeds, and (d) the desulfurized light fraction is further blended in the blending process. Further, (b) the isomerization treatment is to bring the heavy fraction into contact with the isomerization catalyst in the presence of hydrogen, and in particular, the isomerization catalyst is selected from the group consisting of titanium, zirconium and hafnium. A solid acid catalyst in which a platinum group metal component is supported on a carrier containing at least one group metal component as a metal component is preferable.

Moreover, the environmentally friendly clean gasoline according to the present invention is an environmentally friendly clean gasoline produced by the above production method, the research octane number is 92.0 or more, and the 50% by volume distillation temperature is 90 ° C. or less. The aroma content is 1% by volume or less, the olefin content is 20% by volume or less, the isoparaffin content is 60% by volume or more, the total sulfur content is 1 mass ppm or less, and the Reed vapor pressure is 45 kPa or more and 72 kPa or less. The hydrocarbon having 4 carbon atoms is 5% by volume or less, and the isoparaffin having 8 or more carbon atoms is 20% by volume or more and 60% by volume or less.

  According to the production method of the present invention, it is possible to isomerize a fraction having a specific boiling range and to increase the isoparaffin content by producing an alkylate using a component by-produced by the isomerization as a raw material. Even when the sulfur content and the aroma content are sufficiently low, it is possible to efficiently produce clean gasoline that maintains operating performance. Further, the clean gasoline of the present invention can maintain the operation performance even when the sulfur content and the aroma content are sufficiently low by increasing the content of isoparaffin and selecting the distillation properties.

  [Raw material oil] As the raw material oil of the present invention, a hydrocarbon oil obtained in a petroleum refining process or a so-called GTL oil obtained from a hydrocarbon synthesized by a Fischer-Tropsch method can be used. . In particular, the fluid catalytic cracking oil described later is preferably used.

[Heavy fraction] The heavy fraction is obtained by fractionating a fraction containing a boiling point component of at least 120 to 170 ° C. from raw oil. Preferred distillation properties are a 10% distillation temperature of 80 to 130 ° C, particularly 100 to 110 ° C, and a 95% distillation temperature of 160 to 220 ° C, particularly 180 to 200 ° C.
The heavy fraction has aroma content of 10% by volume or less, preferably 5% by volume or less, more preferably 1% by volume or less, and is hydrotreated under the condition that the nuclear hydrogenation reaction proceeds before the isomerization treatment. Although it is preferable, when GTL oil or the like is used as a raw material oil, no particular treatment is required. The heavy fraction preferably has a sulfur content of 5 mass ppm or less, particularly 1 mass ppm or less, and an olefin content of 2 vol% or less, particularly 0.5 vol% or less.

  [Fluid catalytic cracking oil] The process for producing the catalytic cracking oil is not particularly limited to the catalytic cracking apparatus, the operating conditions and the catalyst to be used, and any known production process can be adopted. The catalytic cracking unit uses a catalyst such as amorphous silica alumina, zeolite, etc., in addition to petroleum fractions from light oil to vacuum gas oil, while being obtained from heavy oil indirect desulfurization unit, it can be obtained directly from degassing oil or heavy oil direct desulfurization unit. This is a device that obtains a high octane gasoline base material by catalytic cracking of degassed oil, atmospheric residue oil and the like. For example, UOP catalytic cracking method, flexi cracking method, ultra-orthoflow method, fluid catalytic cracking method such as Texaco fluid catalytic cracking method, RCC method, HOC method, etc. Examples include fluid catalytic cracking.

  [Light fraction] The light fraction is obtained by fractionating a fraction containing a boiling point component of at least 40 to 70 ° C from fluid catalytic cracking oil by distillation or the like. Preferred distillation properties are a 10% distillation temperature of 10 to 60 ° C, particularly 30 to 50 ° C, and a 95% distillation temperature of 40 to 90 ° C, particularly 60 to 75 ° C. Since the fluid catalytic cracked oil contains a large amount of isoparaffins having 4 carbon atoms typified by isobutane, these can be separated and used as raw materials for the alkylation described later.

  [Desulfurization process of light fraction] In the light fraction, the thiol is removed in the desulfurization process to form a desulfurization light fraction. The sulfur content of the desulfurized light fraction is preferably 10 ppm or less, particularly preferably 1 ppm or less. Specifically, the catalytic cracking light fraction is obtained by contacting with an alkaline substance to extract thiols in the catalytic cracking naphtha, or by contacting the desulfurization agent having a sulfur compound adsorption or sorption function with the catalytic cracking light fraction. A method of selectively removing sulfur compounds from the components is a preferred method. In addition, as one of the desulfurization methods, there is a method of hydrotreating in the presence of a catalyst and hydrogen. In the presence of high-pressure hydrogen, olefins are easily hydrogenated, and RON (research method octane number) is It tends to decline. Therefore, the desulfurization treatment is preferably performed in a state where hydrogen is not substantially present or in a hydrogen partial pressure of less than 1 MPa.

  Conventionally, in petroleum refining, sweetening has been carried out to treat the thiol to make the product non-brominated, and it is roughly classified into three types: oxidation sweetening method, extraction sweetening method and extraction oxidation sweetening method. . The oxidation sweetening method only converts thiols into disulfides and cannot reduce the sulfur content, but the extraction sweetening method and the extraction oxidation sweetening method are separated by absorbing the thiols in the oil into the alkaline solution. As a result, sulfur content can be reduced. A known method can be applied as a desulfurization method by alkali treatment in the present invention. Specifically, the Marlox method, the doctor method, and the like disclosed in publicly known documents (Sangyo Tosho Co., Ltd., Petroleum Refining Technology Handbook 3rd Edition, 1981) are preferably used. In sweetening, since olefins are retained as they are, RON does not decrease.

  [Hydrogen fraction hydrogenation process] In the heavy fraction hydrotreatment, aroma (aromatic hydrocarbon) is converted to naphthene (cycloaliphatic) by contacting with a catalyst capable of hydrogenation in the presence of hydrogen. It is preferable to convert to hydrocarbon). The aroma content is preferably reduced to 10% by volume or less, particularly 5% by volume or less.

  Typical characteristics of heavy fractions with reduced aromatic content by nuclear hydrogenation of aromatic hydrocarbons are 1 ppm or less for sulfur content, 1.0 vol% or less for aroma content, and 0.1 vol% or less for olefin content. The saturated content is 99% by volume or more, and the naphthene content is 25 to 60% by volume (of which the naphthene content having 7 or 8 carbon atoms is 10 to 40% by volume).

In a preferred embodiment of nuclear hydrogenation, the catalyst used is a catalyst containing at least one of platinum, palladium, and ruthenium, and these components are usually supported on an inorganic porous carrier such as alumina. Normal reaction conditions are a reaction temperature of 120 to 250 ° C., a reaction pressure of 0.5 to 3.0 MPa, and LHSV of 1.0 to 10 h ⁻¹ . Particularly preferable reaction conditions are a reaction temperature of 180 to 220 ° C., a reaction pressure of 1.8 to 2.2 MPa, and LHSV 4.0 to 6.0 h ⁻¹ . In this step, the aroma content is nuclear hydrogenated to the naphthene content, and the aroma content is 1.0% by volume or less. For nuclear hydrogenation, it is preferable to use a catalyst having a lower acid strength than the isomerization catalyst described later.

It is preferable to hydrodesulfurize as a pre-stage of nuclear hydrogenation. As an aspect thereof, the catalyst used is a catalyst containing at least one of molybdenum, nickel, cobalt, and phosphorus, and is usually an inorganic porous material such as alumina. These components are supported on the carrier. Normal reaction conditions are a reaction temperature of 150 to 300 ° C., a reaction pressure of 0.5 to 3.0 MPa, and LHSV 2.0 to 10 h ⁻¹ . Particularly preferred reaction conditions are a reaction temperature of 180 to 220 ° C., a reaction pressure of 1.8 to 2.2 MPa, and LHSV 4.0 to 6.0 h ⁻¹ . In this step, the sulfur content can be 1 ppm or less and the olefin content can be 0.1 vol% or less. Moreover, this hydrodesulfurization can also be performed in the same process as nuclear hydrogenation.

  [Isomerization treatment] The heavy fraction is subjected to isomerization treatment to obtain an isomerization heavy fraction. By this isomerization treatment, normal paraffin (linear saturated hydrocarbon) in the heavy fraction is converted to isoparaffin (branched saturated hydrocarbon). The isomerization method is not particularly limited, but it is preferable to contact with an isomerization catalyst such as a solid acid catalyst under a hydrogen atmosphere.

  As the isomerization catalyst, a catalyst in which a platinum group metal component is supported on a carrier containing one kind of a group IV metal component selected from titanium, zirconium and hafnium as a metal component is preferable. In particular, as an isomerization catalyst, a platinum group metal component is used as a support containing, as a metal component, one group IV metal component selected from titanium, zirconium and hafnium and one group VI metal component selected from tungsten and molybdenum. Is preferably used (hereinafter also referred to as a platinum tungstate zirconia catalyst) or a support containing zirconia or the like (hereinafter also referred to as a platinum sulfate zirconia catalyst).

As the platinum tungstate zirconia catalyst, zirconium is preferable as the group IV metal component, and tungsten is preferable as the group VI metal component. The catalyst preferably contains a Group IV metal component in an amount of 10 to 72% by weight, particularly 20 to 60% by weight, as the weight of the metal element. Further, it is preferable that the group VI metal component is contained in the catalyst in an amount of 2 to 30% by weight, particularly 5 to 20% by weight, and more preferably 10 to 15% by weight as the metal element weight. Usually, the proportion of sulfuric acid in the catalyst is 0.1% by weight or less as the weight of elemental sulfur. The support is preferably substantially composed of a metal oxide. The metal oxide is defined as including a hydrated metal oxide.
The platinum sulfate zirconia catalyst preferably contains 20 to 72% by weight, especially 30 to 60% by weight of zirconium as the weight of zirconium element in the catalyst. Further, it is preferable that at least a part of the metal component of the metal oxide is aluminum, and the catalyst contains aluminum in an amount of 5 to 30%, particularly 8 to 25% by weight as an aluminum element weight. The proportion of sulfuric acid (SO ₄ ) in the catalyst is 0.7 to 7% by weight, preferably 1 to 6% by weight, particularly 2 to 5% by weight as elemental sulfur. If the sulfuric acid content is too much or too little, the catalyst activity decreases.

  The isomerization catalyst used contains one or more metals selected from platinum group metals. Examples of the platinum group metal include platinum, palladium, ruthenium, rhodium, iridium, and osmium. Preferably, platinum, palladium, ruthenium, particularly platinum is preferably used. The ratio of the platinum group metal component in the catalyst (average value of the platinum group metal component concentration) is 0.01 to 10% by weight, preferably 1 to 5% by weight, as the weight of the metal element.

The specific surface area of the isomerization catalyst is 50 to 500 m ² / g, preferably 100 to 300 m ² / g, particularly 140 to ²⁰⁰ m ² / g. The specific surface area can be measured by a commonly known BET method. The pore structure of the isomerization catalyst can be measured by a nitrogen adsorption method for a pore diameter range of 0.002 to 0.05 μm, and by a mercury intrusion method for a pore diameter range of 0.05 to 10 μm. Pore volume of pores having a pore diameter 0.002~10μm is 0.2 cm ³ / g or more, preferably 0.3 cm ³ / g or more, particularly 0.35cm ³ /g~1.0cm ³ / g. Preferably, the isomerization catalyst is not a powder but a molded shape, so-called pellet shape, and can easily be obtained in a size of 0.5 to 20 mm. 5 to 20 mm, particularly 0.6 to 5 mm is preferably used.

Preferred isomerization reaction conditions are a reaction temperature of 120 to 250 ° C., a reaction pressure of 0.5 to 5.0 MPa, and LHSV of 0.5 to 5 h ⁻¹ , and particularly preferred reaction conditions are a reaction temperature of 180 to 220 ° C. and a reaction pressure of 1 0.8-2.2 MPa, LHSV 1.5-3.0 h ⁻¹ . The reaction conditions are such that a by-product gas (mostly isobutane) is obtained, and the gas is separated and used as a feedstock for the alkylation process.

  [Alkylation step] The alkylation step is a step of producing an alkylate by adding a lower paraffin such as isobutane to a lower olefin such as butane or ethylene. In the present invention, the raw material is a by-product in the isomerization step. And hydrocarbons having 3 and 4 carbon atoms such as isobutane. Moreover, it is preferable to use the component from a catalytic cracking oil as a raw material of an alkylation process. The alkylation step uses an acid catalyst typified by sulfuric acid, and a generally commercialized process can be used. For example, there are exon process, stratoco process, kellogg process, etc. described in “New Oil Refining Process” edited by Petroleum Society. It can be obtained by using sulfuric acid as a catalyst, reacting at about 0 to 10 ° C. in a liquid phase reaction, and separating the obtained isooctanes from an aqueous phase as a catalyst layer. Thereby, a C8 high octane product is obtained. A solid superacid can also be used as the acid catalyst.

  [Blending Step] The clean gasoline according to the present invention can be produced by blending an isomerized heavy fraction and an alkylate, more preferably a light oil fraction. Preferred blending amounts are 40 to 70% by volume of light oil fraction, particularly 50 to 60% by volume, and 10 to 40% by volume of isomerized heavy fraction, particularly 20 to 30% by volume. The alkylate is 5 to 30% by volume, particularly 10 to 20% by volume, and the other substrate is preferably 10% by volume or less, and particularly preferably 5% by volume or less. Other base materials include catalytically modified gasoline base materials, base materials obtained by desulfurizing straight-run naphtha, and MTBE, ethyl t-butyl ether (ETBE), t-amyl ethyl ether (TAEE), ethanol, methanol, and the like. A known gasoline base material such as an oxygen gasoline base material can be used.

  Furthermore, the clean gasoline of the present invention can be blended with one or more fuel oil additives known in the art as needed. Although these compounding quantities can be selected suitably, it is preferable to maintain the total compounding quantity of an additive to 0.1 weight% or less normally. Examples of fuel oil additives that can be used in the gasoline of the present invention include phenolic, amine-based antioxidants, Schiff-type compounds, metal deactivators such as thioamide-type compounds, and organic phosphorus-based surfaces. Anti-ignition agent, detergent / dispersant such as succinimide, polyalkylamine, polyetheramine, anti-icing agent such as polyhydric alcohol or its ether, alkali metal salt or alkaline earth metal salt of organic acid, sulfuric acid of higher alcohol Examples include an auxiliary combustor such as an ester, an anionic surfactant, a cationic surfactant, an antistatic agent such as an amphoteric surfactant, and a colorant such as an azo dye.

  [Environmentally friendly clean gasoline] The clean gasoline of the present invention has a research octane number of 92.0 or more, a 50 volume% distillation temperature of 90 ° C. or less, an aroma content of 1 volume% or less, and an olefin content of 20 volume%. Hereinafter, the isoparaffin content is 60% by volume or more, the total sulfur content is 1 mass ppm or less, and the Reed vapor pressure is 45 kPa or more and 72 kPa or less. Preferably, the carbon number 4 hydrocarbon is 5% by volume or less, particularly 3 The volume fraction of isoparaffin having 8 or more carbon atoms is 20 volume% or more and 60 volume% or less, and particularly 22 volume% or more and 40 volume% or less. The clean gasoline can be used not only as a fuel for an internal combustion engine but also as a fuel for producing a fuel for a fuel cell, for example, hydrogen for a fuel cell, in a reforming process.

  More preferably, the 50 volume% distillation temperature is 80 ° C. or more and 85 ° C. or less, the aroma content is 0.5 volume% or less, and the isoparaffin content is 65 volume% or more and 80 volume% or less.

Examples Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

[Light and heavy fractions]
Hydrocracking of the vacuum gas oil fraction of Middle Eastern crude oil gave a catalytic cracking feedstock. A catalytic cracking substrate FC comprising a catalytic cracking naphtha obtained by treating this with a fluidized bed catalytic cracking device, and a light FC which is a light fraction obtained by fractionating the catalytic cracking substrate FC at a cut temperature of 85 ° C. Obtained heavy FC. Table 1 shows the properties of catalytic cracking substrate FC, light FC and heavy FC.

  The density was measured by the vibration type density test method of JIS K 2249, the Reed method vapor pressure was measured by the Reed method vapor pressure test method of JIS K 2258, and the distillation property was measured by the atmospheric pressure distillation test method of JIS K 2254. The sulfur content was measured by the microcoulometric titration method of JIS K2541. The hydrocarbon component composition was measured by a gas chromatograph method using a JIS K2536 gas chromatographic all-component test method, and RON was measured using a PIONA device manufactured by Hured Packard. The saturated content is the total amount of normal paraffin, isoparaffin, and naphthene.

[Extraction desulfurization of light fractions] The thiols are extracted and removed from the light fraction (light FC) of catalytic cracking base material FC by the Marrox process, and the sulfur content is reduced. The desulfurized light FC which becomes a desulfurized light fraction was obtained. The conditions of the Marlocks method treatment are 10% at normal temperature and normal pressure, and the mixing ratio of the aqueous sodium hydroxide solution to the treated oil. The separated hydrocarbon having 4 or less carbon atoms contains a large amount of isoparaffin represented by 4 carbon atoms and is used as a raw material for alkylation described later. Table 2 shows the properties of desulfurized light FC.

[Hydrogen hydrogenation and isomerization of heavy fractions] Nuclear hydrogenation FC is obtained by subjecting the heavy fraction (heavy FC) of catalytic cracking base FC to nuclear hydrogenation desulfurization, which is a hydrogenation process. Got. This nuclear hydrogenation-type desulfurization treatment can reduce not only the sulfur content by hydrodesulfurization but also the olefin content and aroma content. The catalyst used in the heavy hydrogen nuclear hydrogenation desulfurization treatment uses alumina as a carrier, and contains 0.4 wt% platinum, 3.4 wt% nickel, and 12.3 wt% molybdenum. Is. The reaction conditions were as follows: reaction temperature: 200 ° C., reaction pressure: 2 MPa, LHSV: 5 h ⁻¹ , H ₂ / Oil: 300 L / L. Table 2 shows the properties of nuclear hydrogenated FC.

Nuclear hydrogenation FC was isomerized to obtain nuclear hydrogenation / isomerization FC. The catalyst used for this isomerization (platinum / tungstic acid / zirconia catalyst) was 1.6% by weight of platinum, 37.6% by weight of zirconia, 15.5% by weight of tungsten, and 13.5% by weight of aluminum. 7% by weight is contained. The reaction conditions were as follows: reaction temperature: 240 ° C., reaction pressure: 2 MPa, LHSV: 1.5 h ⁻¹ , H ₂ / Oil: 300 L / L. Table 2 shows the properties of nuclear hydrogenation / isomerization FC.

[Desulfurization and isomerization of heavy fractions] For comparison, desulfurized heavy fractions (desulfurized FCs) were obtained by performing conventional hydrodesulfurization of heavy fractions (heavy FCs) of fluid catalytic cracking oil. It was. The desulfurization catalyst used is one containing alumina as a carrier and containing 3.4% by weight of nickel and 12.3% by weight of molybdenum as metals. The reaction conditions were as follows: reaction temperature: 300 ° C., reaction pressure: 2 MPa, LHSV: 5 h ⁻¹ , H ₂ / Oil: 300 L / L. Table 2 shows the properties of desulfurization FC. In such normal hydrodesulfurization, the sulfur content and the olefin content are reduced, but the nuclear hydrogenation reaction does not occur and the aroma content is not changed.

Subsequently, this desulfurization FC was isomerized to obtain a desulfurization / isomerization FC. The catalyst used for this isomerization (platinum, tungstic acid, zirconia catalyst) was 1.6 wt% platinum, 37.6 wt% zirconia, 15.5 wt% tungsten, and 13.7 wt% aluminum. % Content. The reaction conditions were as follows: reaction temperature: 240 ° C., reaction pressure: 2 MPa, LHSV: 1.5 h ⁻¹ , H ₂ / Oil: 300 L / L. Table 2 shows the properties of desulfurization / isomerization FC.

[Alkylation step] Light olefin and isobutane obtained from a catalytic cracking apparatus and isobutane obtained as a decomposition byproduct of an isomerization reaction are used as raw materials. These gases are fed to the reactor and alkylate is produced in the presence of sulfuric acid. The ratio of olefins to isobutane was 40% by volume to 60% by volume. Excess isobutane was separated and used again as a raw material. The properties of the resulting alkylate are shown in Table 1.

These base materials were blended in the blending amounts shown in Table 3 to prepare gasolines of Example 1 and Comparative Examples 1 to 4. In addition, these properties are shown in Table 3. The reaction conditions of the examples and all the comparative examples were set so that the total sulfur content was 1 ppm by mass or less, and the blending amount was determined based on the amount generated from the catalytic cracking apparatus.
As can be seen from this result, compared to Example 1, Comparative Example 1 does not contain an alkylate, that is, it does not have an alkylation step, so that it has a large amount of light components and has a vapor pressure. Is expensive. In addition, since no nuclear hydrogenation isomerization FC is blended, that is, no nuclear hydrogenation step is provided, the isomerization activity is low and the octane number is low.
In Comparative Example 2, since the nuclear hydroisomerization FC is not blended, that is, since there is no nuclear hydrogenation step, the raw material with a large amount of aroma is isomerized, so that isoparaffin and naphthene are produced. Low and octane number is low. As in these comparative examples 1 and 2, when there is no nuclear hydrogenation step, the isomerization catalyst is poisoned due to the large amount of aroma in the isomerization step, and sufficient isomerization activity cannot be exhibited. It seems to be because.
In Comparative Examples 3 and 4, since the base material that has undergone the isomerization process is not used, the amount of isoparaffin is small, and the generation amount of hydrocarbons having 4 carbon atoms, which is a byproduct of the isomerization process, is small. The amount of alkylate to be obtained is 5% by volume, which is small compared to the examples, and the ratio of isoparaffins having 8 or more carbon atoms derived from the alkylation reaction product is also low, so the octane number is low.

Claims (5)

A fractionation step of fractionating a heavy fraction containing at least a component having a boiling point of 120 to 170 ° C. from a feedstock composed of hydrocarbon;
An isomerization step of isomerizing the heavy fraction having an aroma content of 10% by volume or less into an isomerized heavy fraction;
An alkylation process for producing alkylates using hydrocarbons having 3 and 4 carbon atoms generated in the isomerization process as raw materials;
A method for producing an environmentally friendly clean gasoline, comprising a blending step of blending at least the isomerized heavy fraction and the alkylate into clean gasoline. The feed oil in the fractionation process is a fluid catalytic cracking oil obtained from the oil refining process, and in the fractionation process, a light fraction containing at least a boiling point component of 40 ° C to 70 ° C is separated together with the heavy fraction. A desulfurization step that removes thiols from the light fraction to form a desulfurized light fraction, and the heavy fraction is hydrogenated under a condition in which a nuclear hydrogenation reaction proceeds before the isomerization step. Having a hydrogenation process to treat,
The method for producing environmentally friendly clean gasoline according to claim 1, wherein the desulfurized light fraction is further blended in a blending step. The isomerization treatment according to claim 1, wherein the heavy fraction is contacted with the isomerization catalyst in the presence of hydrogen,
The isomerization catalyst is a solid acid catalyst in which a platinum group metal component is supported on a carrier containing one or more group IV metal components selected from the group consisting of titanium, zirconium and hafnium as a metal component. Item 2. An environmentally friendly clean gasoline manufacturing method according to Item 1. An environmentally friendly clean gasoline produced by the method according to any one of claims 1 to 3, having a research octane number of 92.0 or more, a 50% by volume distillation temperature of 90 ° C or less, and an aroma content. An environmentally friendly clean gasoline having an olefin content of 1 vol% or less, an olefin content of 20 vol% or less, an isoparaffin content of 60 vol% or more, a total sulfur content of 1 mass ppm or less, and a Reed vapor pressure of 45 kPa or more and 72 kPa or less. The environmentally friendly clean gasoline according to claim 4, wherein the hydrocarbon having 4 carbon atoms is 5 vol% or less, and the isoparaffin having 8 or more carbon atoms is 20 vol% or more and 60 vol% or less.