A method for reducing benzene content of naphtha using an aromatization unit

Abstract

A method for reducing benzene content of naphtha by using aromatization device. The method comprises the following steps: after heat exchange and / or heating, the raw material containing benzene naphtha enters a fixed bed aromatization reactor, the raw material methanol and carbon four are mixed and divided into two parts, one part enters from the top of the reactor together with the benzene-containing naphtha, and the other part enters the reactor from the catalyst bed layer by layer; under the action of the characteristic catalyst, the benzene-containing naphtha and the methanol and carbon four are subjected to aromatization reaction to generate gasoline components, at the same time, butene in the carbon four and ethylene propylene generated by the reaction of the methanol and benzene are subjected to alkylation reaction to generate alkylbenzene, so as to reduce the benzene content. The aromatization device is used, gasoline yield is increased, and the benzene content can be significantly reduced. After the raw material naphtha with 10% benzene content passes through the aromatization device, the benzene content of the gasoline product can be reduced to below 0.8%.

Description

Technical Field

[0001] This invention relates to a method for reducing the benzene content of naphtha using an aromatization unit. Specifically, it is a method for obtaining a gasoline product with high yield, high octane number, and low benzene content using a fixed-bed aromatization unit with benzene-containing naphtha, methanol, and C4 as raw materials, under the action of a characteristic catalyst. Background Technology

[0002] Benzene in automobile exhaust is a recognized carcinogen. With the rapid increase in automobile use, environmental pollution has become increasingly prominent. Therefore, my country has formulated the China VI standard for gasoline, which strictly limits the benzene content in gasoline, and aims to fully implement the China VIB standard by 2023. Compared with the China V standard, the China VI standard requires a benzene content (volume fraction) of ≤1% in gasoline to be reduced to ≤0.8%.

[0003] Reducing the benzene content of gasoline for vehicles and producing clean fuel oil of qualified quality has always been one of the main tasks of oil refining enterprises. The main components in the gasoline pool are catalytic cracking gasoline, catalytic reforming gasoline, alkylated gasoline, and C5 / C6 isomerized gasoline. Except for catalytic cracking gasoline, which is produced from heavier feedstocks, the others are all obtained by converting naphtha or light hydrocarbons.

[0004] There are three main ways to reduce the benzene content of gasoline using naphtha or light hydrocarbons as feedstock: first, removing benzene and benzene precursors from the naphtha feedstock; second, optimizing process operating parameters; and third, removing benzene from the product oil. Removing benzene and benzene precursors from the naphtha feedstock requires relatively low investment, but it cannot prevent the formation of benzene during the reaction, resulting in a limited reduction in benzene content. Removing benzene from the product oil mainly involves physical separation methods such as extraction, extractive distillation, and adsorption, as well as chemical conversion methods. Chemical conversion methods primarily include hydrogenation saturation and alkylation for benzene reduction. Hydrogenation saturation is a mature technology, but it inevitably suffers from problems such as gasoline octane number loss and hydrogen consumption. In alkylation for benzene reduction, alkylating agents such as light olefins or alcohols are converted into gasoline components, increasing gasoline yield and octane number.

[0005] CN104927919B discloses a "method for generating olefins and low-benzene gasoline components from naphtha". This method involves extractive distillation of naphtha to obtain extractable oils containing aromatics and C6 cycloalkanes, and extractable oils containing alkanes and C6 cycloalkanes; the residual oil is subjected to steam cracking to obtain cracked gasoline, which is then hydrorefined to obtain hydrorefined cracked gasoline; the extractable oil is then subjected to catalytic reforming to obtain reformate with low benzene content. This method reduces the benzene content in the reformate by removing benzene and benzene precursors from the feedstock naphtha, while simultaneously increasing the feedstock conversion rate through various means such as extractive distillation, steam cracking, and hydrorefining to compensate for the yield loss of gasoline components.

[0006] CN102947251B discloses a "method and apparatus for reducing the benzene content of gasoline by using dilute ethylene alkylation". In the embodiment, a fluidized catalytic cracking reactor provides a 5-50 wt% dilute ethylene feed stream, and a naphtha feed stream passes through a reforming reactor to provide a reforming product benzene feed stream. The reforming product benzene feed stream and the dilute ethylene feed stream are contacted with a UZM-8 alkylation catalyst in an alkylation reactor, where at least 20% of the benzene in the feed stream is converted to alkylbenzene. The feedstock naphtha is first catalytically reformed to obtain a benzene-containing reformate, which is then alkylated to obtain gasoline with low benzene content. This process uses at least three reactors.

[0007] CN109679680B discloses a "catalytic conversion method for light distillate oil". The feedstock light distillate oil in this method refers to gasoline and diesel fractions, or only diesel fraction. The gasoline fraction is selected from at least one of catalytic cracking gasoline, straight-run gasoline, coking gasoline, reformed gasoline, and Fischer-Tropsch gasoline. The method uses a fluidized bed reactor where, under the action of a catalyst, the feedstock light distillate oil and methanol undergo a coupled reaction. The resulting products show reduced yields of dry gas and coke, increased yields of liquefied petroleum gas (LPG), and reduced benzene content in the gasoline product. In the examples, the benzene content of the feedstock light gasoline fraction is 0%, and the benzene content (volume fraction) of the feedstock full gasoline fraction is only 0.51%. The benzene reduction effect was not investigated in the properties of the product gasoline. When the feedstock is diesel fraction, it is co-fed with methanol, resulting in a benzene content of 0.74% in the product gasoline, but the benzene content data of the feedstock diesel fraction is not disclosed.

[0008] CN109054892A discloses "a system and preparation method for producing high-quality gasoline from naphtha coupled with methanol". The method uses naphtha and methanol as raw materials, and a metal-modified HZSM molecular sieve catalyst. When several fluidized bed reactors are connected in series, the heat of reaction is fully utilized to increase the gasoline yield. When several fluidized bed reactors are connected in parallel, the contact time with the catalyst is increased to increase the reaction conversion rate and aromatic selectivity, thereby improving the gasoline octane number. The benzene content (volume fraction) in the gasoline product of this method is reduced to below 0.8%, and the mesitylene concentration is below 0.9%. This method involves a large number of fluidized bed reactors, making the reaction and regeneration operations complex. Furthermore, this method aims to solve the problem of high mesitylene concentration in the methanol-to-gasoline reaction product. No data on the reduction of benzene content is provided in the examples.

[0009] In summary, existing research largely focuses on either catalytically reforming naphtha to obtain reformate, or using other conversion pathways to obtain gasoline fractions, followed by hydrogenation saturation or alkylation to reduce the benzene content of the reformate or gasoline fractions. In this invention, however, the naphtha is directly catalytically reformed in a reactor to produce low-benzene gasoline without pretreatment such as extractive distillation or aromatics extraction. The gasoline product also does not require further benzene reduction treatment.

[0010] This invention employs a fixed-bed aromatization device. Under the action of a characteristic catalyst, benzene-containing naphtha reacts with methanol and C4 olefins to produce gasoline components. Simultaneously, benzene in the naphtha and the benzene produced in the reaction reacts with C4 olefins and methanol to produce alkylbenzenes. This reduces the benzene content of the gasoline product, increases the yield of the gasoline product, and improves the octane number of the gasoline product. Summary of the Invention

[0011] The purpose of this invention is to provide a method for the direct catalytic conversion of benzene-containing naphtha into gasoline products with low benzene content using an aromatization unit. This method also incorporates methanol and C4 feedstocks, fully utilizing the heat effect of the reaction to significantly reduce unit energy consumption. Furthermore, it yields high-yield, high-value-added gasoline products and automotive liquefied petroleum gas (LPG) with low benzene content, thereby improving the economic efficiency of oil refining enterprises.

[0012] To achieve the above objectives, the present invention includes the following steps:

[0013] (1) The benzene-containing naphtha feedstock enters the fixed-bed aromatization reactor from the top of the reactor after heat exchange and / or heating; the methanol and C4 feedstock are mixed and divided into two parts, one part enters the reactor from the top of the reactor together with the benzene-containing naphtha, and the other part enters the reactor in sections between the catalyst beds.

[0014] (2) Under the action of the characteristic catalyst packed in the fixed bed reactor, the raw material naphtha, methanol and C4 together undergo an aromatization reaction to generate gasoline components. At the same time, the benzene in the raw material naphtha and the benzene generated in the reaction process undergo an alkylation reaction with C4 olefins and methanol to generate alkylbenzenes.

[0015] (3) The oil and gas mixture generated by the reaction flows out from the bottom of the reactor and enters the subsequent separation system to recover the liquefied gas and gasoline products generated by the reaction, and a small amount of dry gas is used as fuel for the heating furnace.

[0016] The raw materials used in the method of this invention include benzene-containing naphtha, C4 hydrocarbons, and methanol. Benzene-containing naphtha refers to one or more of straight-run naphtha, catalytically cracked naphtha, oilfield condensate, and hydrocracked naphtha. In this invention, the benzene-containing naphtha is directly catalytically converted into a low-benzene gasoline product via an aromatization unit. The benzene-containing naphtha does not require pretreatment such as extractive distillation or aromatics extraction, and the gasoline product does not require further benzene reduction treatment.

[0017] In step (2) of this invention, under the action of the characteristic catalyst packed in the fixed-bed reactor, the raw material naphtha undergoes an aromatization reaction with methanol and C4 to generate gasoline components; the benzene in the naphtha and the benzene generated during the reaction process undergo an alkylation reaction with the butene in the C4 and the ethylene propylene generated by the methanol to generate alkylbenzene. Methanol and C4, as aromatization raw materials and alkylating agents, not only participate in the reaction, increasing the gasoline yield and improving the gasoline octane number, but also effectively reduce the benzene content of the gasoline product.

[0018] In the same reactor, the naphtha aromatization reaction is a strongly endothermic reaction, the methanol-to-gasoline process is a strongly exothermic reaction, and the alkylation reaction of benzene with C4 olefins and methanol is a strongly exothermic reaction. The addition of methanol and C4 olefins provides heat for the naphtha aromatization reaction. The naphtha aromatization reaction makes full use of the heat of reaction of methanol and C4 olefins, avoids temperature runaway, and simultaneously yields a product distribution with less dry gas and coke and more gasoline.

[0019] In step (1) of this invention, the raw materials methanol and C4 are mixed and then partially or completely fed into the catalyst bed, or the raw materials methanol and C4 are fed separately.

[0020] This invention can control the reaction temperature and regulate the distribution of reaction products by adjusting the feeding method and feed rate of methanol and C4, thereby obtaining the ideal yield of the target product.

[0021] The present invention can also recycle part or all of the liquefied gas and / or gasoline components obtained after product separation back to the reactor for reprocessing.

[0022] Based on the co-aromatization of naphtha and methanol, the addition of low-value-added C4 significantly increases the yield of high-value-added gasoline products, greatly improving refinery profits. Based on the co-aromatization of naphtha and C4, the addition of methanol effectively reduces the benzene content of gasoline products, reduces the yield of dry gas and coke, and reduces catalyst coking and deactivation.

[0023] In step (1) of the present invention, the mass ratio of benzene-containing naphtha to methanol is 10:1 to 1:10, and the mass ratio of benzene-containing naphtha to C4 is 10:3 to 3:10.

[0024] In step (2), the catalytic reaction conditions in the reactor are: reaction temperature 300–500℃, reaction pressure 0.15–1.5 MPa, and feed weight hourly space velocity 0.5–5.0 h⁻¹. -1 .

[0025] In step (3), the oil-gas mixture generated by the reaction flows out from the bottom of the reactor, is heated by a heat exchanger and cooled by a water cooler before entering the separation system. The separation system employs an absorption stabilization system well-known to those skilled in the art. The separation system yields the target products of this method: liquefied petroleum gas (LPG) and gasoline. A small amount of dry gas is used as fuel for the heating furnace and sent to the fuel gas pipeline.

[0026] In industrial implementation, the oil-gas mixture flowing from the bottom of the reactor passes through a heat exchanger and a separator before entering the absorption and desorption system, where dry gas and heavier components are separated. The dry gas is used as fuel for the heating furnace and sent to the fuel gas pipeline. This portion of heavier components, along with the material flowing from the bottom of the separator, enters a stabilizer tower, where liquefied petroleum gas (LPG) and aromatic oil are separated. The LPG is divided into two streams: one stream is directly used as product LPG, and the other is returned to the reactor for reprocessing. The aromatic oil from the bottom of the stabilizer tower is used as a high-octane gasoline component in the separation unit.

[0027] The reactor described in this invention is a fixed-bed reactor, and the characteristic catalyst is packed in sections inside the reactor, with the number of catalyst bed sections being 2 to 6.

[0028] The characteristic catalyst of this invention is a modified ZSM-5 molecular sieve catalyst, which has both aromatization and alkylation functions. The modifying elements of the catalyst include: (1) at least one from Group IIB, Group VIB and Group VIII, preferably at least one from Zn, Cd, Cr, Mo, Fe, Co, Ni, Pd and Pt; (2) Group VA elements, preferably P; and (3) rare earth elements, preferably La and Ce.

[0029] Based on the total weight of the catalyst, the catalyst contains 0.1–10% modifying elements, 40–90% molecular sieves, and 10–50% alumina. The molecular sieves and alumina binder together serve as the carriers for the modifying elements, which are loaded onto the catalyst using an impregnation method.

[0030] The catalyst forming methods are known to those skilled in the art, such as extrusion, tableting, spheroidization, and drop forming. Molecular sieves, aluminum hydroxide, guar gum powder, and other solids are mixed evenly, and appropriate amounts of water and acid (hydrochloric acid, nitric acid, or acetic acid) are added. The mixture is then extruded and kneaded, and finally extruded, dried, and broken into strips, or extruded and rolled into spheres; alternatively, all raw materials are mixed to form a colloid, which is then drop-formed into spheres in a hot oil or oil-ammonia bath. The formed catalyst is dried at room temperature to 150°C. After drying, a metal is deposited onto the catalyst by impregnation with a metal-soluble salt (generally a nitrate). Then, it is calcined at 400–600°C in an air or vapor atmosphere for 1–12 hours to obtain the catalyst of this invention.

[0031] The present invention has the following effects:

[0032] (1) The benzene-containing naphtha is directly catalytically converted into gasoline products with low benzene content through an aromatization unit. The benzene-containing naphtha does not need to undergo pretreatment such as extraction distillation or aromatic extraction, and the gasoline products do not need further benzene reduction treatment.

[0033] (2) The alkylation of benzene in the raw naphtha and the benzene generated in the reaction process are carried out simultaneously in the same reactor. The process is simple and reliable, and the benzene reduction effect is good.

[0034] (3) Both methanol and C4 raw materials participated in the reaction as aromatization raw materials and alkylating agents and were converted into high-value-added gasoline products, which increased the gasoline yield, improved the gasoline octane number, and effectively reduced the benzene content of gasoline products.

[0035] (4) The addition of raw materials methanol and C4 allows the aromatization and alkylation reactions to be carried out simultaneously in the same reactor. The heat effect of the exothermic reaction is efficiently utilized by the endothermic reaction, avoiding the overheating of the reaction while obtaining a product distribution with less dry gas and coke and more gasoline.

[0036] (5) Based on the co-aromatization of naphtha and methanol, the addition of low-value-added C4 significantly increases the yield of high-value-added gasoline products, greatly improving refinery profits; based on the co-aromatization of naphtha and C4, the addition of methanol effectively reduces the benzene content of gasoline products, reduces the yield of dry gas and coke, and reduces catalyst coking and deactivation.

[0037] (6) The naphtha containing benzene of the present invention is catalytically converted to obtain gasoline products with low benzene content, with liquefied petroleum gas as a byproduct. The entire process is simple, reliable, easy to operate, and has lower energy consumption, making it suitable for the industrial production of low-benzene gasoline. In industrial applications, the benzene content of naphtha with a benzene content of 10% is reduced to below 0.8% in gasoline products after passing through an aromatization unit. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the process flow of the method of the present invention, but the present invention is not limited thereto.

[0039] 1-Reaction product primary heat exchanger, 2-Reaction product secondary heat exchanger, 3-Heating furnace, 4-Aromatization reactor, 5-Water cooler, 6-Reaction product separator, 7-Rich gas compressor, 8-Compressor post-separator, 9-Absorption / desorption tower, 10-Reaction product liquid pump, 11-Stabilization tower feed pump, 12-Desorption tower reboiler, 13-Absorption tower mid-section extraction cooler, 14-Absorption tower mid-section extraction reflux pump, 15-Stabilization tower, 16-Stabilization tower top cooler, 17-Stabilization tower top reflux tank, 18-Stabilization tower top reflux pump, 19-Stabilization tower reboiler, 20-Gas water cooler, 21-Stabilization tower bottom pump.

[0040] like Figure 1 The process flow of this method shown is as follows:

[0041] After heat exchange and heating, the feedstock naphtha enters the fixed-bed aromatization reactor from the top. The feedstock methanol and C4 are mixed and divided into two parts. One part, together with the naphtha, enters the reactor from the top after heat exchange and heating, while the other part enters the reactor in sections between the catalyst beds.

[0042] In a fixed-bed reactor, naphtha reacts with methanol and C4 hydrocarbons through aromatization and alkylation reactions to produce an oil-gas mixture containing the target products gasoline and liquefied petroleum gas (LPG). After being cooled by a heat exchanger, the mixture enters a product separator. The gas phase exits from the top of the separator and enters a rich gas compressor, while the liquid phase exits from the bottom and, after being pressurized by a pump, is sent to a stabilizer. The material from the rich gas compressor enters a post-compressor separator. The gas phase exits from the top of the post-compressor separator and enters an absorption / desorption tower, while the liquid phase exits from the bottom and, after being pressurized by a stabilizer feed pump, enters the stabilizer.

[0043] The absorbent in the absorption-desorption tower is gasoline from the bottom of the stabilization tower. This gasoline is cooled, pressurized, and then pumped to the top of the absorption-desorption tower. The absorption-desorption tower is equipped with a mid-section extraction and reflux system; the mid-section extract is drawn from the side of the tower, cooled, and pressurized, and then returned to the tower. The absorption-desorption tower is also equipped with a reboiler. A small amount of dry gas exits from the top of the absorption-desorption tower and can be used as fuel for a heater.

[0044] A reboiler is installed at the bottom of the stabilizer tower. The liquefied petroleum gas (LPG) component is distilled from the top of the tower, cooled, and then enters the stabilizer tower reflux tank. The liquid component exits from the bottom of the tank, is pressurized by the stabilizer tower reflux pump, and a portion is refluxed back to the stabilizer tower, while the remainder is discharged as LPG product. Gasoline exits from the bottom of the stabilizer tower, is cooled, and a portion is used as an absorbent in the absorption / desorption tower, while the remainder is discharged as gasoline product. Detailed Implementation

[0045] The present invention will be further described below with reference to embodiments, but the present invention is not limited thereto.

[0046] Raw material specifications

[0047] (1) The experimental feedstock was a mixture of naphtha, methanol and C4, with a mixing ratio of 70:20:10. The naphtha was taken from a plant in Xinjiang, and its properties are shown in Table 1; the methanol was industrial methanol, and its properties are shown in Table 2; the C4 was taken from the etherified C4 of a catalytic cracking unit in a plant in Ningxia, and its composition is shown in Table 3.

[0048] (2) The catalyst model is NMTO-11, which is a strip with a butterfly-shaped cross-section of 2.1mm × 3.2mm and a length of 4–10min. This catalyst model is produced by Beijing Huier Sanji Green Chemical Technology Co., Ltd., and contains 58.2% ZSM-5, 1.5% P2O5, 5.8% La2O3, 0.46% Fe2O3 and the balance Al2O3. The ZSM-5 molecular sieve is synthesized by in-situ crystallization method, and the silicon-to-aluminum ratio is 220.

[0049] Example 1

[0050] This example illustrates the effectiveness of a method for reducing the benzene content in naphtha using an aromatization device, based on experimental data.

[0051] The experimental setup was a 200 mL fixed-bed reactor. The raw materials, naphtha, methanol, and C4 ether, were separately pumped into the preheating furnace using metering pumps, and then entered the fixed-bed reactor from the top. The resulting oil-gas mixture underwent heat exchange, and the pressure was controlled by a regulating valve. After passing through a condenser and a gas-liquid separator, the liquid produced by the reaction was separated and weighed. The gas was measured using a wet flow meter. The liquid and gas samples were analyzed by gas chromatography to determine their composition, and the yield (based on the weight of the raw naphtha) was calculated.

[0052] 90g of catalyst was loaded into the reactor. The feedstock flow rates were naphtha 40g / h, methanol 11.4g / h, and C4 5.7g / h. The preheating temperature was 200℃, the average catalyst bed temperature was 400℃, and the reaction pressure was 0.15MPa (gauge pressure). The reaction was carried out continuously for 7 days, with material balance measured daily, and two gas samples taken for composition analysis and one liquid sample taken for composition analysis. After the 7-day reaction, the catalyst was unloaded and coke was burned, and the coke yield was calculated. Tables 4 and 5 show the average data for the 7 days.

[0053] Table 1. Main Properties of Naphtha

[0054] Density, g / mL 0.718 Sulfur content, ppm 26 Benzene content, wt% 6.8 Alkane content, wt% 52.4 Cycloalkanes content, wt% 35.2 Aromatic hydrocarbon content (including benzene), wt% 11.5 Olefin content, wt% 0.9 Distillation range, °C Initial boiling point 38 10％ 58 50％ 105 90％ 138 Dry 164

[0055] Table 2. Main properties of methanol

[0056] purity >99.5％ Molecular formula <![CDATA[CH3OH]]> molecular weight 32 Density (0℃), g / mL 0.8100 Boiling point, °C 64.6 Specific heat, kcal / ℃mol 18.4 Heat of combustion, keal / mol 174 Flash point, °C 9.5 (closed), 16 (open)

[0057] Table 3. Post-etherification C4 composition

[0058] C3 0.45 n-Butane 12.62 Isobutane 39.23 n-Butene 16.62 Isobutylene 0.84 transbutene 17.06 maleic butene 12.8 C5 0.38 total 100

[0059] Table 4 Reaction conditions and product distribution of the examples

[0060] catalyst NMTO-11 Reaction temperature, °C 400 Reaction pressure, MPa 0.15 <![CDATA[Total feed space velocity, h -1 > 0.63 Distribution of reaction products, wt% hydrogen 0.04 methane 1.15 Ethane 1.84 ethylene 3.22 propane 8.68 propylene 12.42 n-Butane 8.50 Isobutane 15.32 1-Butene 2.82 Isobutylene 3.53 C5+ aromatic oil 42.42 coke 0.06 total 100

[0061] Table 5 Properties of Gasoline Components

[0062] Density (20°C), g.cm -3 ]] 0.7486 Octane number (RON) 97.6 Distillation range, °C Primary distillation 42 10％ 85 50％ 142 90％ 185 Content of each component, wt% benzene 0.58 Toluene 11.6 xylene 21.8 Total aromatics 48.2

Claims

1. A method for reducing the benzene content in naphtha using an aromatization device, comprising the following steps: (1) The benzene-containing naphtha feedstock enters the fixed-bed aromatization reactor from the top of the reactor after heat exchange and / or heating; the methanol and C4 feedstock are mixed and divided into two parts, one part enters the reactor from the top of the reactor together with the benzene-containing naphtha, and the other part enters the reactor in sections between the catalyst beds. (2) Under the action of the characteristic catalyst packed in the fixed bed reactor, the raw material naphtha, methanol and C4 together undergo an aromatization reaction to generate gasoline components. At the same time, the benzene in the raw material naphtha and the benzene generated in the reaction process undergo an alkylation reaction with C4 olefins and methanol to generate alkylbenzenes. (3) The oil and gas mixture generated by the reaction flows out from the bottom of the reactor and enters the subsequent separation system to recover the liquefied gas and gasoline products generated by the reaction, and a small amount of dry gas is used as fuel for the heating furnace. The catalytic reaction conditions in the reactor were: reaction temperature 400–500℃, reaction pressure 0.15–1.5 MPa, and feed weight hourly space velocity 0.5–5.0 h⁻¹. -1 ; The characteristic catalyst is a modified ZSM-5 molecular sieve catalyst, and its modifying elements include at least one element from Group IIB, Group VIB and Group VIII, Group VA elements and rare earth elements.

2. The method according to claim 1, characterized in that... The benzene-containing naphtha is directly catalytically converted into gasoline with low benzene content through an aromatization unit. The benzene-containing naphtha does not undergo extraction distillation or aromatics extraction pretreatment, and the gasoline does not require further benzene reduction treatment.

3. The method according to claim 1, characterized in that... In step (2), under the action of the characteristic catalyst, the raw material naphtha undergoes an aromatization reaction with methanol and C4 to generate gasoline components; the benzene in naphtha and the benzene generated in the reaction process react with butene in C4 and ethylene propylene generated by methanol to undergo an alkylation reaction to generate alkylbenzene; methanol and C4, as aromatization raw materials and alkylating agents, not only participate in the reaction, increasing the gasoline yield and improving the gasoline octane number, but also effectively reduce the benzene content of gasoline products.

4. The method according to claim 1 or 3, characterized in that... The aromatization of naphtha is a strongly endothermic reaction, while the process of producing gasoline from methanol is a strongly exothermic reaction. The alkylation reaction of benzene with C4 olefins and methanol is also a strongly exothermic reaction. The addition of raw materials methanol and C4 provides heat for the aromatization of naphtha. The aromatization of naphtha makes full use of the heat of reaction of methanol and C4, avoids overheating, and simultaneously produces a product distribution with less dry gas and coke and more gasoline.

5. The method according to claim 1, characterized in that... In step (1), the raw materials methanol and C4 are mixed and then partially or completely fed into the catalyst bed, or the raw materials methanol and C4 are fed separately.

6. The method according to claim 1 or 5, characterized in that... By adjusting the feeding method and feed rate of methanol and C4, controlling the reaction temperature, and adjusting the distribution of reaction products, the ideal yield of the target product can be obtained.

7. The method according to claim 1, characterized in that... The raw materials include benzene-containing naphtha, C4 hydrocarbons, and methanol; wherein the mass ratio of benzene-containing naphtha to methanol is 10:1 to 1:10, and the mass ratio of benzene-containing naphtha to C4 hydrocarbons is 10:3 to 3:

10.

8. The method according to claim 1, characterized in that... The reactor is a fixed-bed reactor, and the characteristic catalyst is packed in sections inside the reactor, with 2 to 6 catalyst bed sections.

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