CN109679693B

CN109679693B - Method for producing high-octane gasoline from naphtha

Info

Publication number: CN109679693B
Application number: CN201710972760.2A
Authority: CN
Inventors: 刘洪全; 马爱增; 张秋平; 于中伟
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2017-10-18
Filing date: 2017-10-18
Publication date: 2021-02-09
Anticipated expiration: 2037-10-18
Also published as: CN109679693A

Abstract

The invention relates to a method for producing high-octane gasoline from naphtha, which comprises the steps of hydrofining, first fractionation and second fractionation of naphtha raw materials, directly separating out methylcyclopentane, cyclohexane and multi-branched alkane in the naphtha as gasoline components, carrying out catalytic reforming on a first heavy fraction obtained by the first fractionation, and carrying out isomerization reaction on a second light fraction obtained by the second fractionation to obtain the gasoline components. The method can improve the gasoline yield, optimize the gasoline composition, improve the contents of isoparaffin and cycloparaffin in the gasoline and reduce the contents of aromatic hydrocarbon and normal paraffin.

Description

Method for producing high-octane gasoline from naphtha

Technical Field

The invention relates to a method for producing high-octane gasoline from naphtha.

Background

Modern automobile engines require gasoline to have a high octane number. Aromatic hydrocarbon and olefin are important high-octane gasoline blending components, but the aromatic hydrocarbon and the olefin are not easy to combust completely, enter the atmosphere along with automobile exhaust and are one of important factors for causing air pollution. Due to environmental issues, the restrictions on olefins and aromatics in high octane gasoline are becoming more and more stringent. The highly branched isoparaffin and some naphthene such as methyl cyclopentane not only have higher octane number, but also burn completely, and the function of the highly branched isoparaffin and some naphthene as a final blending component for upgrading gasoline in the future is increasingly prominent.

Naphtha is a mixture of hydrocarbons such as normal paraffins, isoparaffins, naphthenes, and aromatics. Naphtha can be converted into reformate rich in aromatic hydrocarbon through a catalytic reforming process, and the reformate rich in high-octane isoparaffin is generated through alkane isomerization reaction, so that the naphtha is an important raw material for producing high-octane gasoline blending components. With depletion of petroleum resources and deterioration and heaviness of crude oil, naphtha resources are becoming increasingly valuable. Therefore, how to convert the valuable naphtha resource into high-octane gasoline blending components to realize the optimal utilization of naphtha is a problem which is greatly concerned and needs to be solved.

Chinese patent CN101570698A discloses a catalytic conversion method of naphtha with a boiling range of 40-260 ℃, which comprises the following steps: (1) the method comprises the following steps of (1) hydrofining naphtha in the presence of a hydrofining catalyst, and then fractionating and cutting the hydrofined naphtha into light fraction, middle fraction and heavy fraction, (2) discharging the light fraction out of a device or contacting the light fraction with a light hydrocarbon isomerization catalyst to carry out light hydrocarbon isomerization reaction, (3) separating the middle fraction into one or more fractions to carry out segmented reforming reaction, and (4) contacting the heavy fraction with a light catalyst to carry out light reaction.

Chinese patent CN101759513A discloses a method for utilizing naphtha, which comprises the following steps: (1) separating the naphtha into a component rich in normal paraffins and a component rich in non-normal paraffins; (2) cutting the normal alkane rich component obtained in the step (1) into C₅/C₆Fraction sum ≥ C₇Fractionating; (3) c obtained in the step (2)₅/C₆Isomerizing the distillate to obtain C₅/C₆An isoparaffin; (4) not less than C obtained in the step (2)₇Carrying out catalytic cracking on the fraction to obtain ethylene and propylene; (5) and (2) reforming the component rich in non-normal alkane obtained in the step (1) to obtain aromatic hydrocarbon or high-octane value blending component.

Chinese patent CN103717713A discloses a method for refining naphtha by parallel operation of paraffin isomerization unit and reforming unit, the specific embodiment comprises: separating the naphtha feedstock into light naphtha and heavy naphtha; separating the heavy naphtha into a paraffinic stream and a non-paraffinic stream; introducing the light naphtha to a first isomerization unit and the paraffinic hydrocarbon fluid to a second isomerization unit; a non-paraffinic stream is introduced to the reformer and the resulting effluents are combined to form a gasoline blend.

Chinese patent CN103396833A discloses a method for producing motor gasoline from synthetic naphtha, which comprises the following steps: feeding the naphtha synthesized by coal indirect liquefaction process into a fractionating tower for fractionation, and fractionating the C fractionated in the first line of the tower₅-C₆Sending the normal paraffin into a hydroisomerization process for treatment; sending the fraction with the temperature of more than or equal to 80 ℃ obtained at the bottom of the tower into a fixed bed catalytic reforming process for treatment; and finally, mixing the generated oil obtained by the normal paraffin hydroisomerization process and the fixed bed catalytic reforming process, feeding the mixture into a degassing tower for degassing, and obtaining the vehicle gasoline component at the bottom of the tower.

Chinese patent CN104711017A discloses a process for producing a gasoline having an octane number higher than 95 from a naphtha fraction comprising paraffins and naphthenes, said process comprising the following steps: a) passing the naphtha fraction to a first catalytic reforming unit to convert at least a portion of the paraffins and/or naphthenes to aromatics and produce hydrogen; b) withdrawing a first effluent and a hydrogen stream from the first catalytic reforming unit; c) passing the first effluent to a separation unit to separate a light hydrocarbon fraction containing linear paraffins and a heavy hydrocarbon fraction containing unconverted paraffins and/or naphthenes; d) passing the light hydrocarbon fraction to an isomerization unit to produce an isomerized oil; e) passing the heavy hydrocarbon fraction to a second catalytic reforming unit; f) reformate containing aromatic compounds is withdrawn from the second catalytic reforming unit.

In the method, naphtha is generally divided into 2-3 fractions which are respectively used as feed for isomerization and reforming of the naphtha, and part of the fractions are also used as raw materials for preparing ethylene and propylene by catalytic cracking. However, none of the above methods relates to the problem of optimizing the use of high octane components such as methylcyclopentane (RON ═ 91.3), 2-dimethylpentane (RON ═ 92.8), 2, 4-dimethylpentane (RON ═ 83.1), 2, 3-trimethylbutane (RON ═ 100.0), and cyclohexane (RON ═ 83.0) which are originally present in the naphtha feedstock.

Disclosure of Invention

The invention aims to provide a method for producing high-octane gasoline from naphtha, which can improve the gasoline yield, optimize the gasoline composition, improve the contents of isoparaffin and naphthene in the gasoline and reduce the contents of aromatic hydrocarbon and normal paraffin.

In order to achieve the above object, the present invention provides a process for producing a high-octane gasoline from naphtha, the process comprising:

(1) contacting a naphtha raw material with a hydrofining catalyst and performing hydrofining to obtain hydrofined naphtha;

(2) performing first fractionation on the hydrofined naphtha obtained in the step (1) by taking the boiling point of cyclohexane as a cut point to obtain a first light fraction and a first heavy fraction, wherein the end point of the first light fraction is not higher than the boiling point of cyclohexane, and the initial point of the first heavy fraction is higher than the boiling point of cyclohexane;

(3) contacting the first heavy fraction obtained in the step (2) with a catalytic reforming catalyst and carrying out catalytic reforming to obtain reformed oil;

(4) performing second fractionation on the first light fraction obtained in the step (2) by taking the boiling point of methylcyclopentane as a cutting point to obtain a second light fraction, a methylcyclopentane fraction and a second heavy fraction, wherein the final boiling point of the second light fraction is lower than the initial boiling point of the methylcyclopentane fraction, and the initial boiling point of the second heavy fraction is higher than the final boiling point of the methylcyclopentane fraction;

(5) contacting the second light fraction obtained in the step (4) with an isomerization catalyst and carrying out isomerization reaction to obtain an isomerized oil;

(6) and (4) carrying out aromatic extraction on the second heavy fraction obtained in the step (4) to obtain benzene and a debenzolized third heavy fraction.

The invention separates the high-octane components such as methylcyclopentane, cyclohexane, multi-branched isoparaffin and the like in the naphtha raw material by twice fractionation and aromatic extraction, directly uses the components as gasoline components, reforms the first heavy fraction obtained by the first fractionation to produce high-octane gasoline, isomerizes the second light fraction, can improve the gasoline yield of naphtha, optimizes the gasoline composition, increases the content of the high-octane components such as isoparaffin, cycloparaffin and the like in the gasoline, and reduces the content of aromatic hydrocarbon and normal paraffin.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic flow diagram of one embodiment of the process of the present invention.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The invention takes the boiling point of cyclohexane as a cutting point to separate hydrofined naphtha into a first light fraction and a first heavy fraction, and the first light fraction is fractionated for the second time, methylcyclopentane in the hydrofined naphtha is separated to be directly used as a gasoline component, and a second heavy fraction containing high-octane components such as cyclohexane, multi-branched isoparaffin (such as 2, 2-dimethylpentane, 2, 4-dimethylpentane and 2,2, 3-trimethylbutane) and the like is obtained at the same time, the second heavy fraction is subjected to aromatic hydrocarbon extraction to remove benzene and then directly used as a gasoline component, and the first heavy fraction is subjected to catalytic reforming to produce high-octane gasoline, so that the methylcyclopentane and the cyclohexane in the naphtha can be prevented from being converted into benzene, the benzene content of the gasoline can be increased, and the C-C ratio can be avoided₇The isoparaffin is converted into aromatic hydrocarbon or cracked into micromolecule under the high-temperature reaction condition of reforming, so that the gasoline yield is reduced; subjecting the second light fraction freed of high-octane components to C₅/C₆The isomerization can avoid the cracking of the high-octane components into small molecules and reduce the yield of gasoline on one hand, and can avoid the damage to the isomerization catalyst on the other hand and prolong the service life of the isomerization catalyst on the other hand.

In the invention, the naphtha raw material in the step (1) is C₅-C₁₁The hydrocarbon (C) may, for example, be selected from the group consisting of straight-run naphtha, hydrocracked naphtha, coker naphtha, catalytically cracked naphtha and oilsAt least one of field condensate.

In the present invention, the hydrofining in step (1) is used to saturate olefins in the naphtha feedstock and remove impurities such as nitrogen, oxygen, sulfur, etc., and it is preferable that the resulting hydrofined naphtha have a sulfur content of less than 0.5. mu.g/g, a nitrogen content of less than 0.5. mu.g/g, an arsenic content of less than 1.0ng/g, and a lead content of less than 10 ng/g. The hydrofinishing conditions may include: the temperature is 260-460 ℃, preferably 280-440 ℃, the pressure is 1-8MPa, preferably 1.6-4.0MPa, and the feeding volume space velocity is 1-20h^-1Preferably 2-10h^-1Hydrogen/hydrocarbon volume ratio of (10-1000): 1, preferably (50-600): 1. the hydrofinishing catalyst is preferably a catalyst having the capability of hydrogenating saturated olefins while also having the capability of hydrodesulfurization, denitrogenation and deoxidation, and may comprise, on a dry basis, 5 to 49 mass% of a hydrogenation-active component oxide, which may comprise an oxide of at least one metal selected from the group consisting of Co, Ni, Fe, W, Mo, Cr, Bi, Sb, Zn, Cd, Cu, In and rare earths, 0.1 to 1.0 mass% of a halogen, preferably an alumina support, and 50.4 to 94.9 mass% of an inorganic oxide support, preferably chlorine.

In the present invention, in the step (2), the first fractionation of the hydrotreated naphtha is carried out with the boiling point of cyclohexane being the cut point, that is, the cyclohexane is cut into the first light fraction, and the heavy fraction having a boiling point higher than the boiling point of cyclohexane is cut into the first heavy fraction.

In the present invention, the catalytic reforming in step (3) is used to reform hydrocarbon molecules in the first heavy fraction to produce high octane gasoline component, and it should be noted that the catalytic reforming reaction product includes part of C₄The following gas products may be removed by fractionation or the like to obtain the reformate. The conditions for catalytic reforming may include: the temperature is 300-600 ℃, preferably 350-530 ℃, more preferably 400-520 ℃, the pressure is 0.1-3.0MPa, preferably 0.2-2.0MPa, and the hydrogen/hydrocarbon molar ratio is (0.5-30): 1, preferably (1-8): 1, the volume (volume of the first heavy fraction) space velocity is 0.1-50h^-1Preferably 1-30h^-1More preferably 2-25h^-1. The catalytic reforming catalyst may comprise, on a dry basis, an inorganic oxide support, preferably an alumina support, and from 0.01 to 5.0 mass% of a group VIII metal, preferably platinum, and from 0.01 to 5.0 mass% of a halogen, calculated on a support basis.

The catalytic reforming in the present invention may employ a continuous (moving bed) reforming technique, a semi-regenerative (fixed bed) reforming technique, or a cyclic regenerative reforming technique. If a continuous (moving bed) reforming technique is employed, the catalytic reforming catalyst preferably comprises an inorganic oxide support and a group VIII metal in an amount of 0.01 to 3.0 mass%, 0.01 to 5.0 mass% Sn, and 0.01 to 5.0 mass% halogen, calculated on the support; if semi-regenerative (fixed bed) reforming techniques are employed, the catalytic reforming catalyst preferably comprises an inorganic oxide support and a group VIII metal in an amount of from 0.01 to 3.0 mass%, Re from 0.01 to 5.0 mass%, and halogen from 0.01 to 5.0 mass%, calculated on the support. Wherein Sn or Re is the second metal component, it is further preferred that if a continuous (moving bed) reforming technique or a semi-regenerative (fixed bed) reforming technique is employed, the catalytic reforming catalyst may further contain one or more third metal components of at least one selected from the group consisting of alkali metals, alkaline earth metals, rare earth elements, In, Co, Ni, Fe, W, Mo, Cr, Bi, Sb, Zn, Cd and Cu.

In one embodiment, the catalytic reforming catalyst is prepared by a conventional method, and specifically, a shaped inorganic oxide carrier, for example, a spherical or bar type, is prepared, then the first metal component and the halogen are introduced by impregnation, if the catalyst contains the second metal component and/or the third metal component, the second metal component and/or the third metal component are preferably introduced into the carrier, finally the first metal component and the halogen are introduced, and the carrier after all the metal components are introduced is dried and calcined at the temperature of 450-650 ℃ to obtain the catalytic reforming catalyst in an oxidized state. Before use, the oxidation-state catalytic reforming catalyst needs to be reduced in a hydrogen-containing atmosphere at 315-650 ℃ to obtain the reduction-state catalytic reforming catalyst.

In the present invention, the second fractionation in the step (4)For obtaining a second light fraction, a methylcyclopentane fraction and a second heavy fraction. When the second fractionation is carried out in the step (4), the distillation range for separating the methylcyclopentane fraction can be 70-75 ℃ under the pressure of 0.05-0.2 MPa. Fractionating C in the second light fraction obtained₅-C₆The content of alkanes is preferably higher than 95 mass%, more preferably higher than 98 mass%; the content of methylcyclopentane in the methylcyclopentane fraction is preferably higher than 95 mass%, more preferably higher than 98 mass%; the second heavy fraction mainly contains cyclohexane, 2, 3-trimethylbutane, 2, 4-dimethylpentane, benzene, and 2, 2-dimethylpentane, and the content of the above-mentioned hydrocarbons in the second heavy fraction is preferably higher than 95% by mass, more preferably higher than 98% by mass.

In the present invention, the isomerization reaction in step (5) is used to isomerize the second light fraction to increase its octane number, and the conditions may include: at a temperature of 50-350 ℃, preferably 80-300 ℃, a pressure of 0.1-5.0MPa, preferably 0.5-4MPa, a hydrogen/hydrocarbon molar ratio of (0.01-10): 1, preferably (0.02-8): 1, the volume space velocity is 0.1-20h^-1Preferably 1-5h^-1. The isomerization catalyst may be a solid super acid catalyst, a zeolite-containing catalyst, or a chlorinated alumina catalyst.

In one embodiment, the solid super acid catalyst comprises 0.05-2.0 mass% of a group VIII metal and 98.0-99.95 mass% of a mixed oxide support carrying sulfate groups, the mixed oxide support comprising 30-90 mass% of zirconia, 1-30 mass% of silica and 9-40 mass% of alumina, the sulfur content in the catalyst being 0.5-3.5 mass%. Preferably, the mixed oxide support comprises 40 to 80 mass% of zirconia, 4 to 24 mass% of silica and 16 to 36 mass% of alumina, the group VIII metal is Pt or Pd, and the sulfur content in the catalyst is 1.0 to 2.5 mass%. The solid super acidic catalyst can be prepared by a conventional method, and the specific steps can be as follows: (1) contacting soluble zirconium salt with an alkali solution to form zirconium hydroxide precipitate, then carrying out hydrothermal treatment, filtering, and drying a solid product to prepare hydrous zirconium oxide; (2) uniformly mixing and drying aluminum hydroxide and silica sol, adding an ammonium chloride solution, washing, filtering and drying to prepare a mixture of silicon oxide and aluminum oxide; (3) uniformly mixing the products of the first two steps, soaking the products in aqueous solution of sulfuric acid, ammonium sulfate or ammonium bisulfate, drying, forming and roasting the solid to prepare a catalyst carrier; (4) the active metal component is introduced into the carrier by an impregnation method, and the catalyst is prepared by drying and roasting, wherein the roasting temperature can be 400-650 ℃, and preferably 450-600 ℃.

In one embodiment, the zeolite-containing catalyst comprises a support and a group VIII metal (preferably Pt or Pd) in an amount of 0.01 to 2.0 mass% based on the support, the support comprising 10 to 90 mass% of alumina and 10 to 90 mass% of a zeolite selected from mordenite, zeolite Beta or a mixture of both, the support preferably comprising 10 to 80 mass% of mordenite, 10 to 80 mass% of zeolite Beta and 10 to 50 mass% of alumina. The zeolite-containing catalyst can be prepared by a conventional method, and specific steps can include: mixing hydrogen-type mordenite, or hydrogen-type mordenite, hydrogen-type Beta zeolite and aluminum hydroxide powder or pseudo-boehmite according to a required proportion, molding, drying and roasting to obtain a carrier, introducing a VIII group metal component by an impregnation method, and then drying and roasting, wherein the roasting temperature can be 400-650 ℃, preferably 450-600 ℃.

In one embodiment, the chlorided alumina catalyst includes an alumina support and a group VIII metal (preferably Pt or Pd) in an amount of 0.01 to 5.0 mass% and chlorine in an amount of 3.0 to 15.0 mass% as the first metal component, calculated on a support basis. The chlorided alumina catalyst can be prepared by a conventional method, and specific steps can comprise: firstly preparing a molded alumina carrier, then dipping and introducing a metal component, drying the alumina carrier introduced with the metal component, and roasting at the temperature of 450-650 ℃ to obtain the oxidation state catalyst. Prior to the introduction of chlorine, the oxidized catalyst is preferably reduced in a hydrogen-containing atmosphere at 650 ℃ at 315 ℃ to obtain a reduced catalyst. Finally, the reduced catalyst is contacted with chlorine-containing organic matter or high-temperature sublimed aluminum chloride gas, so that chlorine is introduced.

The isomerization reaction may be carried out in a one-pass scheme or a cyclic scheme. The one-pass flow is to pass the reaction raw material through an isomerization reaction zone, and a normal paraffin and isoparaffin separation tower is not arranged before and after the reaction. The circulation flow is to separate normal paraffin and isoparaffin before, after or before the isomerization reaction, and send the separated low octane value component into the reactor for the isomerization reaction. Thus, the cycle flow generally results in an isomerate with higher isoparaffin content and higher octane number than the once-through flow.

In the invention, the aromatic extraction in the step (6) is preferably extractive distillation, and the specific steps can be as follows: and (3) feeding the second heavy fraction into an extraction and rectification tower to contact with an extraction solvent, directly discharging non-aromatic fractions in the second heavy fraction as third heavy fractions from the top of the extraction and rectification tower, discharging a rich solvent rich in benzene from the bottom of the extraction and rectification tower into a solvent separation tower, separating the benzene from the extraction solvent, and returning the obtained lean solvent to the extraction and rectification tower for recycling. In the extraction and rectification tower, the volume ratio of the extraction solvent to the second heavy fraction is (2-8): 1, preferably (3-6): 1, controlling the temperature at the top of the tower to be 60-120 ℃, preferably 65-110 ℃, the temperature at the bottom of the tower to be 120-170 ℃, preferably 125-165 ℃, and the operating pressure to be 0.1-0.3MPa, preferably 0.1-0.2MPa, wherein the extraction solvent is at least one selected from sulfolane, 2-methyl sulfolane and 2, 4-dimethyl sulfolane, preferably sulfolane.

The invention will be further illustrated by the following specific embodiments, but the invention is not limited thereto.

As shown in fig. 1, a naphtha feedstock is first hydrofinished to saturate olefins in the naphtha feedstock while removing sulfur-, nitrogen-and oxygen-containing impurities to yield a hydrofinished naphtha.

The hydrofinished naphtha is passed to a first fractionation to obtain a first light fraction and a first heavy fraction, the cut point being the boiling point of cyclohexane, such that a fraction having an end point not exceeding cyclohexane is cut into the first light fraction and a fraction having an initial point exceeding cyclohexane is cut into the first heavy fraction.

And (2) feeding the first heavy fraction into a catalytic reforming device for catalytic reforming to obtain reformed oil rich in aromatic hydrocarbon, wherein the benzene content in the first heavy fraction of the reforming raw material and the content of precursors of benzene generated from cyclohexane, methylcyclopentane and the like are extremely low, so that the obtained reformed oil is low in benzene content, does not need aromatic hydrocarbon extraction, and can be directly fed into a gasoline pool as a high-octane gasoline product component.

And further carrying out second fractionation on the first light fraction to cut the first light fraction into three fractions, namely a second light fraction, a methylcyclopentane fraction and a second heavy fraction. The second fractionation takes the methylcyclopentane fraction as a division point, and components with an end point lower than the initial point of the methylcyclopentane fraction are cut into the second light fraction, and components with an initial point higher than the end point of the methylcyclopentane fraction are cut into the second heavy fraction.

The second light fraction is rich in C₅And C₆The paraffin is a high-quality isomerization raw material, and is sent into a paraffin isomerization unit for isomerization reaction to obtain the isomerized oil with higher octane value, and the isomerized oil is a high-quality gasoline blending component and can be directly sent into a gasoline pool.

The methyl cyclopentane is mainly used in the fraction of the methyl cyclopentane obtained by the second fractionation, the Research Octane Number (RON) of the methyl cyclopentane is as high as 91.3, and the methyl cyclopentane is an ideal high-octane number gasoline blending component and can be directly sent to a gasoline pool.

And the second heavy fraction obtained by the second fractionation contains benzene, the second heavy fraction is sent to an aromatic extraction device, and is subjected to extractive distillation to obtain benzene and a benzene-removed third heavy fraction, and the third heavy fraction is an ideal high-octane gasoline blending component and can be directly sent to a gasoline pool.

The invention is further illustrated by the following examples, but is not limited thereto.

In the examples of the invention and the comparative examples:

the Research Octane Number (RON) of gasoline is measured by a GB/T5487-2015 method;

the composition of hydrocarbons (oils) is determined by gas chromatography (foreign equivalent standard number: ASTM D6733-01).

C_n ⁺Fraction (abbreviated as C)_n ⁺) Refers to a hydrocarbon fraction containing carbon atoms of n or more, wherein n is a natural number greater than 1.

Examples of the invention

(1) And hydrofining the naphtha raw material.

In a 20 ml fixed bed continuous flow reactor, 20 ml of a hydrorefining catalyst A containing, on a dry basis, 0.03 mass% of CoO, 2.0 mass% of NiO, and 18.5 mass% of WO was charged₃0.5 mass% of Cl and 78.97 mass% of Al₂O₃。

A naphtha feedstock having the composition and properties shown in table 1 was prepared at 290 ℃, a pressure of 2.0MPa, a hydrogen/hydrocarbon volume ratio of 200: 1. the space velocity of the feeding volume is 8.0h^-1Introducing the mixture into the reactor filled with the catalyst A to perform hydrofining. The reaction product was fed into a water cooler, separated into gas-liquid two phases, measured separately and subjected to compositional analysis, and the composition and properties of the hydrorefined naphtha obtained after hydrorefining were as shown in table 2.

(2) And a first fractionation of the hydrorefined naphtha.

Feeding the refined hydrogenated naphtha obtained in the step (1) into a fractionating tower for first fractionation, controlling the pressure of the fractionating tower to be 0.15MPa, and obtaining a first light fraction with the distillation range of 31-85 ℃ and a first heavy fraction with the distillation range of 85-161 ℃, wherein the yields and the compositions of the obtained first light fraction and first heavy fraction are shown in Table 3.

(3) Catalytic reforming of the first heavy fraction.

In a 100 ml fixed bed continuous flow reactor, 50 ml of catalytic reforming catalyst B was charged, and at a reaction mass inlet temperature of 520 ℃, a pressure of 0.34MPa, a hydrogen/hydrocarbon molar ratio of 2.5: 1. the space velocity of the feeding volume is 2.0h^-1Under the conditions of (1) catalytic reforming, rectifying the catalytic reformed product to obtain C₅ ⁺The reformate was reformed and the reaction results are shown in table 4. The carrier of the catalytic reforming catalyst B is gamma-Al₂O₃The carrier had a Pt content of 0.36 mass%, a Sn content of 0.30 mass%, and a Cl content of 1.02 mass%.

(4) And a second fractionation of the first light fraction.

And (3) taking the first light fraction obtained in the step (2) as a raw material for further fractionation and cutting, sending the light fraction into a fractionating tower for second fractionation, controlling the pressure of the fractionating tower to be 0.12MPa, and obtaining a second light fraction with the distillation range of 31-70 ℃, a methylcyclopentane fraction with the distillation range of 70-75 ℃ and a second heavy fraction with the distillation range of 75-85 ℃, wherein the yields of the three fractions are 59.36 mass%, 23.38 mass% and 17.26 mass%, respectively, and the compositions of the fractions are shown in Table 5.

As can be seen from Table 5, the second light fraction obtained by further fractional cutting is designated C₅-C₆The paraffin is the main paraffin, and the content of isopentane and dimethylbutane with higher octane numbers is lower, so that the method is a high-quality paraffin isomerization raw material. The purity of the methylcyclopentane fraction reaches 97.37 mass%, the Research Octane Number (RON) of the fraction reaches 91, and the fraction can be directly sent into a gasoline pool as a blending component. The second heavy fraction is a more desirable high octane gasoline blending component of other species than benzene.

(5) And isomerizing the second light fraction.

The second light fraction is heated at the temperature of 170 ℃, the pressure of 1.6MPa and the volume space velocity of 1.2h^-1Hydrogen/hydrocarbon molar ratio 2: 1 under the action of a solid super acidic catalyst C to obtain an isomerized oil, and the reaction results are shown in Table 6. Catalyst C consisted of 0.3 mass% Pt and 99.7 mass% sulfate-supported mixed oxide of zirconia, alumina and silica in a 60: 24: 16, and the sulfur content in the catalyst was 1.95 mass%.

(6) And extracting aromatic hydrocarbon from the second heavy fraction.

And (2) taking sulfolane as an extraction solvent, feeding a second heavy fraction with the composition shown in the table 5 into an extractive distillation tower to contact with the sulfolane for extractive distillation, wherein the mass ratio of the extraction solvent to the second heavy fraction is 5: 1, controlling the temperature of the top of the extraction rectifying tower to be 100 ℃, the temperature of the bottom of the extraction rectifying tower to be 140 ℃, and the operating pressure of the extraction tower to be 0.15 MPa. The benzene-rich solvent is obtained from the bottom of the extraction tower, and the raffinate without benzene is obtained from the top of the extraction tower. And (3) distilling the benzene-containing rich solvent to separate sulfolane from benzene, and recycling the sulfolane obtained by separation. The raffinate was washed with water to remove traces of residual solvent, and a third heavy fraction containing no benzene was obtained, which had a RON of 88.3 and a composition shown in table 7.

And (3) feeding the isomerized oil obtained in the step (5), the methylcyclopentane fraction obtained in the step (4), the third heavy fraction obtained in the step (6) and the reformed oil obtained in the step (3) into a gasoline pool to be mixed to obtain a gasoline component. The yields, compositions and RON of gasoline obtained by operating naphtha in steps (1) to (6) are shown in Table 8.

Comparative example 1

The hydrofined naphtha obtained in the step (1) in the example 1 is sent into a fractionating tower to obtain a light fraction with the distillation range of 31-70 ℃ and a heavy fraction with the distillation range of 70-161 ℃. The yields and compositions of the light and heavy fractions obtained are shown in table 3.

The obtained heavy fraction was used as a catalytic reforming raw material, catalytic reforming was carried out in the same manner as in the step (3) in example 1, and the reforming reaction product was rectified to obtain C₅ ⁺The reformate was reformed and the reaction results are shown in table 4.

The obtained light fraction was used as an isomerization raw material, and the isomerization reaction was carried out in the same manner as in the step (5) in example 1.

The yields, compositions and RON of gasoline obtained by subjecting naphtha to the above reaction and separation are shown in Table 8.

Comparative example 2

The hydrorefined naphtha obtained in step (1) of example 1 was fractionated and cut in the same manner as in step (2) of example 1 to obtain a light fraction having an end point not higher than the boiling point of cyclohexane and a heavy fraction (C) having an initial point higher than the boiling point of cyclohexane₇ ⁺)；

The obtained light fraction was used as an isomerization raw material, isomerization was carried out by the method of step (5) in example 1, and the isomerized product was distilled to obtain C₅ ⁺The oil isomerate and the reaction results are shown in Table 6.

The heavy fraction (C) obtained₇ ⁺) Catalytic reforming was carried out as a reforming raw material in the same manner as in step (3) in example 1 to obtain a reformate.

As can be seen from Table 4, the heavy fraction obtained after the fractional cutting according to the process of the invention is catalytically reformed into gasoline (C) compared with comparative example 1₅ ⁺) The yield is basically equivalent, but the benzene content in the gasoline is greatly reduced, C₇ ⁺The aromatic hydrocarbon content is greatly improved, and the octane number of the gasoline is also improved.

As can be seen from Table 6, compared with comparative example 2, the isomerization reaction of the second light fraction after the second fractionation by the method of the present invention results in higher gasoline yield, lower benzene content in gasoline, greatly increased isoparaffin content, and higher gasoline octane number.

As is apparent from Table 8, in the inventive example, as compared with comparative example 1, the gasoline yield was improved by 0.33 mass%, the contents of isoparaffin and naphthene in the gasoline were respectively improved by 2.08 mass% and 0.89 mass%, the contents of normal paraffin and aromatic hydrocarbon were respectively reduced by 2.58 mass% and 0.38 mass%, and the RON of the gasoline was improved by 1 unit; compared with the comparative example 2, the method of the invention has the advantages that the gasoline yield is improved by 0.07 mass percent, the contents of isoparaffin and cycloparaffin in the gasoline are respectively improved by 1.76 mass percent and 6.15 mass percent, the contents of normal alkane and arene are respectively reduced by 3.07 mass percent and 4.84 mass percent, particularly, the benzene content is reduced most obviously and reaches 7.06 mass percent, and the RON of the gasoline is improved by 1 unit.

The comparison shows that the naphtha is converted into gasoline components by the method, so that the gasoline yield is improved, the gasoline composition is optimized, the content of clean components such as isoparaffin, cycloparaffin and the like in the gasoline is improved, the content of aromatic hydrocarbon and normal paraffin is reduced, and the method is an optimized naphtha utilization method.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

TABLE 5

TABLE 6

TABLE 7

Composition of the third heavy fraction	Content, mass%
		Methylcyclopentane	2.23
Dimethyl pentane	18.27
		Trimethylbutane	0.70
Cyclohexane	78.80

TABLE 8

Claims

1. A process for producing a high octane gasoline from naphtha, the process comprising:

2. The method of claim 1, wherein the naphtha feedstock in step (1) is at least one selected from the group consisting of straight run naphtha, hydrocracked naphtha, coker naphtha, catalytically cracked naphtha, and oil field condensate.

3. The process of claim 1, wherein the hydrofinishing conditions in step (1) include: the temperature is 260 ℃ and 460 ℃, the pressure is 1-8MPa, and the space velocity of the feeding volume is 1-20h^-1Hydrogen/hydrocarbon volume ratio of (10-1000): 1.

4. the process according to claim 1, wherein the hydrorefining catalyst comprises, on a dry basis, 5 to 49 mass% of a hydrogenation-active component oxide comprising an oxide of at least one metal selected from the group consisting of Co, Ni, Fe, W, Mo, Cr, Bi, Sb, Zn, Cd, Cu, In and rare earths, 0.1 to 1.0 mass% of a halogen and 50.4 to 94.9 mass% of an inorganic oxide support.

5. The process of claim 1 wherein the hydrofined naphtha obtained in step (1) has a sulfur content of less than 0.5 μ g/g, a nitrogen content of less than 0.5 μ g/g, an arsenic content of less than 1.0ng/g and a lead content of less than 10 ng/g.

6. The process of claim 1, wherein the conditions of the catalytic reforming in step (3) comprise: the temperature is 300-: 1, the volume space velocity is 0.1-50h^-1。

7. The process of claim 1 wherein the catalytic reforming catalyst comprises an inorganic oxide support and a group VIII metal in an amount of 0.01 to 5.0 mass%, calculated on a dry basis, of halogen in an amount of 0.01 to 5.0 mass%, calculated on a support basis.

8. The process as claimed in claim 1, wherein the second fractionation in step (4) is carried out at a pressure of 0.05 to 0.2MPa with a distillation range of 70 to 75 ℃ for the separation of the methylcyclopentane fraction.

9. The process of claim 1, wherein the isomerization conditions of step (5) comprise: temperature ofThe degree is 50-350 ℃, the pressure is 0.1-5.0MPa, and the hydrogen/hydrocarbon molar ratio is (0.01-10): 1, the volume space velocity is 0.1-20h^-1。

10. The process of claim 1, wherein the isomerization catalyst is selected from a solid super acid catalyst, a zeolite-containing catalyst, or a chlorinated alumina catalyst.

11. The method as claimed in claim 1, wherein the aromatic extraction in the step (6) is extractive distillation, and the volume ratio of the extraction solvent to the second heavy fraction is (2-8): 1, controlling the temperature at the top of the tower to be 60-120 ℃, the temperature at the bottom of the tower to be 120-170 ℃ and the operating pressure to be 0.1-0.3MPa, wherein the extraction solvent is at least one of sulfolane, 2-methyl sulfolane and 2, 4-dimethyl sulfolane.