A process for producing aromatic and isomeric alkanes gasoline

Abstract

A method for producing aromatic hydrocarbon and isomeric alkane gasoline, characterized by comprising: treating a C6-C8 alkane raw material rich in normal alkane and / or mono-branched alkane through a process comprising hydrodesulfurization and hydrodenitrification, dehydration, fractional desulfurization, dehydration and alkane aromatization reaction to obtain aromatic hydrocarbon and isomeric alkane gasoline; in the fractional desulfurization and dehydration, the material treated through hydrodesulfurization and hydrodenitrification, dehydration is sequentially subjected to first adsorption, sulfur conversion and second adsorption, and a dehydration step is arranged after the second adsorption to make the water content lower than 1 ppm. The method can convert low-octane alkane into aromatic hydrocarbon and high-octane isomeric alkane gasoline.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for producing aromatic hydrocarbons and isomeric alkanes gasoline, in particular, a method for producing aromatic hydrocarbons and high-octane isomeric alkanes gasoline and enriching hydrogen from a feedstock rich in C6-C8 linear alkanes and / or mono-branched alkanes. BACKGROUND

[0002] BTX (benzene, toluene, xylene) is a basic and important organic raw material in petroleum chemical industry, mainly derived from catalytic reforming of naphtha and pyrolysis gasoline. With large-scale development and utilization of shale gas, ethane replaces naphtha as a cracking raw material for ethylene production, resulting in a decrease in the production of aromatic hydrocarbons from pyrolysis gasoline, and with the continuous increase in the production capacity of downstream products of aromatic hydrocarbons, the gap of aromatic hydrocarbons is becoming more and more obvious, so the production technology of more aromatic hydrocarbons has a clear market demand. At present, the bifunctional reforming catalyst used in the traditional naphtha reforming, whether it is platinum-rhenium or platinum-tin series, has poor performance for the dehydrocyclization aromatization reaction of C6 and C7 alkanes in naphtha, and with the increase of the processing capacity of the reforming device, the efficient utilization of C6 and C7 alkanes in the reforming raffinate has become a problem to be solved.

[0003] At present, for the C6-C8 paraffin aromatization technology, the typical process technology is Chevron Company's Aromax process and UOP Company's RZ Platforming process based on Pt / KL zeolite catalyst. The characteristics of these two processes are to selectively convert low-octane low-aromatic potential raw materials rich in C6-C8 paraffins into aromatic hydrocarbons, which is a process technology for producing aromatic hydrocarbons. L molecular sieve is a one-dimensional pore structure, and sulfur and water in the raw material will cause the aggregation and growth of Pt grains, and these larger Pt grains will block the pores of the L molecular sieve, so that the reaction molecules cannot contact with the active center, thereby causing the activity and selectivity of the alkanes aromatization reaction to decrease rapidly. Therefore, the Pt / KL catalyst has a relatively high requirement for the sulfur and water content in the raw material, and is highly sensitive to sulfur and water, which is much higher than that of the traditional reforming catalyst. The sulfur content in the raw material should not be greater than 0.1 ppm, and the water content should not be greater than 1 ppm. US4456527 discloses that when the sulfur content in the raw material is greater than 0.1 ppm, the activity and aromatic hydrocarbon yield of a non-acidic molecular sieve catalyst loaded with Group VIII metal, such as a Pt / BaKL catalyst, decrease, deactivation occurs, and the stability decreases significantly.

[0004] US4925549 discloses a method for removing residual sulfur from naphtha feed, which comprises first passing the naphtha feed through a reforming catalyst which is not very sensitive to sulfur, then through a solid sulfur adsorbent K / Al2O3, and finally through a L zeolite catalyst which is highly selective and highly sensitive to sulfur, so that the sulfur content is reduced to less than 0.05 ppm. US5322615 discloses a method for removing sulfur from naphtha feed containing sulfur, which comprises first passing the naphtha feed through an adsorbent containing NiO, then through a catalyst containing Group VIII metal to convert organic sulfur into hydrogen sulfide, and then through a solid sulfur adsorbent containing alkali metal or alkaline earth metal, so that the sulfur content is reduced to less than 10 ppb. SUMMARY

[0005] The present application aims to provide a method for producing high-value-added aromatic hydrocarbons and high-octane isomeric alkanes gasoline and simultaneously producing hydrogen from a feedstock of a fraction rich in C6-C8 linear alkanes and / or mono-branched alkanes (such as light naphtha, reforming raffinate, etc.) through a combined process comprising hydrogenation desulfurization and denitrification, dehydration, fractional refining, deep desulfurization and dehydration, and high-sulfur-sensitivity zeolite aromatization.

[0006] The method for producing aromatic hydrocarbons and isomeric alkanes gasoline provided by the present application is characterized by comprising: treating a C6-C8 alkane feedstock rich in n-alkanes and / or mono-branched alkanes through hydrogenation desulfurization and denitrification, dehydration, fractional desulfurization and dehydration, and alkane aromatization to obtain aromatic hydrocarbons and isomeric alkanes gasoline; in the fractional desulfurization and dehydration, the material after hydrogenation desulfurization and denitrification is sequentially subjected to first adsorption, sulfur conversion and second adsorption, and a dehydration step is provided after the second adsorption to reduce the water content to less than 1 ppm.

[0007] The method provided by the present application comprises:

[0008] (1) hydrogenation desulfurization and denitrification and dehydration: a C6-C8 alkane feedstock rich in n-alkanes and / or mono-branched alkanes is subjected to hydrogenation pretreatment and dehydration by contacting with hydrogen to obtain a preliminary dehydration material, and then contacted with a sulfur protection agent to obtain a first material, wherein the sulfur content and nitrogen content of the preliminary dehydration material are not higher than 2 ppm, and the H2O content is not higher than 50 ppm, and the sulfur content and nitrogen content of the first material are not higher than 0.5 ppm, and the H2O content is not higher than 20 ppm;

[0009] (2) Staged desulfurization and dehydration: the first material as described in step (1) is contacted with sulfur adsorbent I for first adsorption, then with sulfur conversion catalyst, and then with sulfur adsorbent II for second adsorption, and finally dried and dehydrated to obtain a second material with sulfur content less than 0.1 ppm and water content less than 1 ppm;

[0010] (3) Alkane aromatization reaction: the second material as described in step (2) is subjected to aromatization reaction with hydrogen under zeolite catalyst, and the product is separated into aromatic component and non-aromatic component, the non-aromatic component being isomeric alkane gasoline.

[0011] In the method, the sulfur protection agent as described in step (1) comprises a carrier and active components loaded thereon, the carrier being Al2O3, and the active components being selected from one of copper oxide, zinc oxide, activated carbon and molecular sieve, the content of the active components being 15-50% by mass based on the mass of the sulfur protection agent, the contact temperature being 40-200°C, and the volume space velocity being 4-20h -1 . In the first material, the sulfur content is 0.2-0.5 ppm, and the water content is 5-20 ppm.

[0012] In the method, the first material as described in step (2) is contacted with sulfur adsorbent I for first adsorption, and the reaction conditions include: temperature of 120-200°C, pressure of 0.3-1.0 MPa, volume space velocity of 4-20h -1 , and hydrogen-hydrocarbon molar ratio of 0-1. The sulfur adsorbent I is a bimetallic adsorbent, which contains a first metal component and a second metal component, the first metal component being selected from nickel or copper, and the second metal component being selected from manganese or titanium; the sulfur conversion agent is an organic sulfur conversion inorganic sulfur catalyst containing Group VIII metal and optional metal potassium; and the sulfur adsorbent II is an adsorbent containing alkali metal and / or alkaline earth metal metal oxide.

[0013] In step (2), the contacting with sulfur conversion catalyst has the following reaction conditions: temperature of 250-400°C, pressure of 0.3-1.0 MPa, volume space velocity of 4-12h -1 , and hydrogen-hydrocarbon molar ratio of 0.1-3. The sulfur conversion agent comprises carrier alumina and Group VIII metal and optional metal K loaded on the carrier alumina, the Group VIII metal being Pt and / or Pd, the mass ratio of the Group VIII metal being 0.2-2% and the mass ratio of metal K being 0-0.5% based on the mass of the carrier alumina.

[0014] In step (2), the contacting with sulfur adsorbent II for second adsorption has the following reaction conditions: temperature of 250-350°C, pressure of 0.3-1.0 MPa, volume space velocity of 4-12h -1, the molar ratio of hydrogen to hydrocarbon is 0.1-3. The sulfur adsorbent II comprises an inorganic oxide carrier and a metal oxide supported on the inorganic oxide carrier, the inorganic oxide carrier is Al2O3 and / or SiO2, and the metal oxide is an oxide of an alkali metal and / or an alkaline earth metal; the alkali metal is Na or K, and the alkaline earth metal is Ca or Mg; the mass fraction of the metal in the metal oxide is 10-20% based on the mass of the inorganic oxide carrier.

[0015] In the method, the reaction conditions of the aromatization reaction in step (3) include: the temperature is 430-550 ℃, the pressure is 0.1-2.0 MPa, the molar ratio of hydrogen to hydrocarbon is 0.1-10, and the volume space velocity is 0.5-10.0 h -1 The zeolite catalyst comprises L zeolite and platinum supported thereon, and the content of platinum is 0.5-2.0 mass%, and the content of W heterocrystal in the L zeolite is less than 0.3 mass%, both of which are calculated based on the L zeolite.

[0016] In the method, the hydrogen used in steps (1) and (2) is from new hydrogen supplement or from recycled hydrogen; before being mixed with the alkane material, the new hydrogen supplement enters a make-up gas dryer for dehydration, and the recycled hydrogen enters a recycle gas dryer for dehydration, so that the water content in the hydrogen is less than 5 ppm.

[0017] In the method, after the aromatization reaction, the reaction product is subjected to gas-liquid separation, and the obtained liquid phase is subjected to aromatic extraction to separate aromatic components and non-aromatic components therefrom.

[0018] In the method, the non-aromatic components are all or partially returned to continue the alkane aromatization reaction.

[0019] In the C6-C8 alkane raw material rich in n-alkanes and / or single branched alkanes, the content of n-alkanes and / or single methyl alkanes is not less than 50 mass%, preferably not less than 63 mass%, the content of S is 2-500 ppm, and the content of H2O is 20-500 ppm.

[0020] In the C6-C8 alkane raw material rich in n-alkanes and / or single branched alkanes, the content of C6-C7 alkanes is not less than 80 mass%, preferably not less than 85 mass%, the content of C5 - alkanes is not more than 10 mass%, the content of C8 + alkanes is not more than 10 mass%, the content of S is 2-300 ppm, and the content of H2O is 20-300 ppm.

[0021] The C6-C8 alkane enriched in normal and / or single branched alkane is at least one of narrow cut refined naphtha, reformate, hydrocracking gasoline, aromatic raffinate, Fischer-Tropsch naphtha and alkylate, with S content of 2-500 ppm and H2O content of 20-500 ppm.

[0022] The C6-C8 alkane enriched in normal and / or single branched alkane is C6 alkane, C7 alkane or a mixture of C6 and C7 alkane or C6, C7 and C8 alkane, with S content of 2-300 ppm and H2O content of 20-300 ppm. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The figure is a flow chart of the method of the present application.

[0024] Figure 1 The figure is a flow chart of the method of the present application. DETAILED DESCRIPTION

[0025] The present application provides a combined process for producing aromatics, high octane dimethyl / multimethyl isomeric alkane gasoline and hydrogen, comprising: treating a C6-C8 alkane feedstock enriched in normal and / or single branched alkane by hydrogenation desulfurization and denitrification, dehydration, fractional desulfurization, dehydration and alkane aromatization to obtain aromatics and isomeric alkane gasoline; in the fractional desulfurization and dehydration, the material treated by hydrogenation desulfurization and denitrification, dehydration is sequentially treated by first adsorption, sulfur conversion and second adsorption, and a dehydration step is provided after the second adsorption to make the water content lower than 1 ppm. The method of the present application has high yield of aromatics and isomeric alkane gasoline, and long service life of sulfur adsorbent I, sulfur adsorbent II, sulfur protective agent, feedstock drying agent and aromatization catalyst.

[0026] In the present application, the C6-C8 alkane raw material rich in normal alkane and / or single branched alkane has a normal alkane and / or single methyl alkane content of not less than 50% by mass, preferably not less than 63% by mass, a S content of 2-500 ppm, and a H2O content of 20-500 ppm.

[0027] The C6-C8 alkane raw material rich in normal alkane and / or single branched alkane has a C6-C7 alkane content of not less than 80% by mass, preferably not less than 85% by mass, a C5 - alkane content of not more than 10% by mass, a C8 + alkane content of not more than 10% by mass, a S content of 2-300 ppm, and a H2O content of 20-300 ppm.

[0028] The C6-C8 alkane raw material rich in normal alkane and / or single branched alkane is at least one of narrow fraction refined naphtha, reforming product oil, hydrocracking gasoline, aromatic raffinate, Fischer-Tropsch synthesis naphtha, and alkylate product oil, has a S content of 2-500 ppm, and a H2O content of 20-500 ppm.

[0029] The C6-C8 alkane raw material rich in normal alkane and / or single branched alkane is C6 alkane, C7 alkane, or a mixture of C6 and C7 alkane or C6, C7 and C8 alkane, has a S content of 2-300 ppm, and a H2O content of 20-300 ppm.

[0030] The method provided by the present application comprises:

[0031] (1) Hydrogenation desulfurization and denitrification: the C6-C8 alkane raw material rich in normal alkane and / or single branched alkane is subjected to hydrogenation pretreatment and dehydration by contacting with hydrogen to obtain a preliminary dehydration material, and then is contacted with a sulfur protective agent to obtain a first material, wherein the sulfur content and nitrogen content of the preliminary dehydration material are not higher than 2 ppm, and the H2O content is not higher than 50 ppm, and the sulfur content and nitrogen content of the first material are not higher than 0.5 ppm, and the H2O content is not higher than 20 ppm;

[0032] (2) Fractionated desulfurization and dehydration: the first material of step (1) is subjected to first adsorption by contacting with a sulfur adsorbent I, then is contacted with a sulfur conversion catalyst, then is subjected to second adsorption by contacting with a sulfur adsorbent II, and finally is subjected to drying and dehydration to obtain a second material with a sulfur content of less than 0.1 ppm and a water content of less than 1 ppm;

[0033] (3) Alkane aromatization reaction: the second material of step (2) is subjected to aromatization reaction by contacting with hydrogen in the presence of a zeolite catalyst, and the product is separated into an aromatic component and a non-aromatic component, and the non-aromatic component is isomeric alkane gasoline.

[0034] In the method described, step (1) involves pretreating C6-C8 alkane feedstock rich in n-alkanes and / or branched alkanes by contacting them with hydrogen. This pretreats impurities, including those containing sulfur, nitrogen, and oxygen, by converting them into H2S, NH3, and H2O, which are then separated. The hydrogenation catalyst used in the pretreat is selected from those known in the art, including group VIB and group VIII metals on an inorganic oxide support and a supported substrate, such as Co-Mo, Ni-Mo, Ni-W, and Ni-Co-W system catalysts. The reaction pressure is 1.5–3.0 MPa, the reaction temperature is 250–350 °C, and the volume hourly space velocity is 6–12 h⁻¹. -1 The hydrogen / hydrocarbon molar ratio is 0.1–2. The reaction products undergo gas-liquid separation at a high-efficiency fractionation unit to remove most impurities such as sulfur, nitrogen, and water. The products then enter a dehydration tower for further dehydration, separating dissolved hydrogen, H2S, HCl, cracked gas (C1, C2, and C3 components), and water from the pre-hydrogenated product oil. The dehydration tower operates at a pressure of 0.80–1.2 MPa, with a top temperature of 70–120°C and a bottom temperature of 200–230°C.

[0035] To prevent the adverse effects of reaction fluctuations and protect the sulfur adsorbent and sulfur converter in the subsequent staged deep desulfurization step (2), the material after hydrogenation pretreatment and purification is preferably contacted with a sulfur protective bed by a sulfur protective agent. The sulfur protective agent serves to reduce the adsorption amount of the sulfur adsorbent in the subsequent deep desulfurization process before it is applied; it also protects the sulfur adsorbent and sulfur converter in the subsequent deep desulfurization process from adverse effects of reaction fluctuations, such as excessive sulfur due to operational abnormalities. Conventional sulfur adsorbents are generally used as the sulfur protective agent, as they are relatively inexpensive. The sulfur protectant for a sulfur-protected bed comprises a carrier and an active component supported thereon. The carrier is Al₂O₃, and the active component is selected from copper oxide, zinc oxide, activated carbon, and molecular sieves. The content of the active component is 15-50% by mass. Based on the mass of the sulfur protectant, the contact temperature with the sulfur protectant in the sulfur-protected bed is 40-200°C, which is the bed temperature of the sulfur protectant. The volume hourly space velocity (HHSV) is 4-20 h⁻¹. -1 After the hydrogenation pretreatment in step (1) and the primary desulfurization, denitrification and dehydration treatment in the sulfur protective bed, the first material has a sulfur content and nitrogen content not higher than 0.5 ppm, an H2O content not higher than 20 ppm, As and Hg both less than 1 ppb, Cu and Pb both less than 10 ppb, and Si less than 1 ppm. Preferably, the sulfur content is 0.2 to 0.5 ppm and the water content is 5 to 20 ppm.

[0036] Preferably, the first material can be further subjected to appropriate fractionation in a fractionation column to obtain a C6-C8 alkane material rich in n-alkanes and / or mono-methyl alkane, and further remove water in the raw material.

[0037] The raw material is subjected to primary desulfurization, denitrification and dehydration in step (1) to obtain a first material, and then subjected to staged desulfurization and dehydration in step (2).

[0038] In step (2), the first material is contacted with a sulfur adsorbent I for first adsorption to remove residual inorganic sulfur in the first material, and the reaction conditions include a temperature of 120-200°C, a volume space velocity of 4-20 h-1, and a hydrogen / hydrocarbon molar ratio of 0-1. -1 The sulfur adsorbent I is a bimetallic adsorbent, which contains a first metal component and a second metal component, the first metal component is selected from nickel or copper, and the second metal component is selected from manganese or titanium; preferably, the sulfur adsorbent I includes a carrier and two metal oxides supported on the carrier, the carrier includes Al2O3 and SiO2, the first metal oxide is selected from NiO or CuO, and the second metal oxide is selected from MnO2 or TiO2; the mass fraction of the first metal oxide is 20-50%, the mass fraction of the second metal oxide is 5-15%, the mass fraction of SiO2 is 5-20%, and the mass fraction of Al2O3 is 15-70%, based on the mass of the sulfur adsorbent I; preferably, the mass fraction of the first metal oxide is 30-40%, the mass fraction of the second metal oxide is 5-10%, the mass fraction of SiO2 is 10-15%, and the mass fraction of Al2O3 is 35-55%, based on the mass of the sulfur adsorbent I. The sulfur adsorbent I can be loaded into a single container or two containers, and the two containers can be used in series or in parallel, and one of the containers can be removed for regeneration or replacement of the adsorbent.

[0039] In step (2), after the first adsorption, the material enters a sulfur conversion zone and is contacted with a sulfur conversion agent for a sulfur conversion reaction to convert residual organic sulfur into H2S, and the reaction conditions include a temperature of 250-400°C, a pressure of 0.3-1.0 MPa, a volume space velocity of 4-12 h-1, and a hydrogen / hydrocarbon molar ratio of 0.1-3. -1 The sulfur conversion agent includes a carrier alumina and a Group VIII metal and optional metal K supported on the carrier alumina, the Group VIII metal is Pt and / or Pd; the mass fraction of the Group VIII metal is 0.2-2%, and the mass fraction of the metal K is 0-0.5%, based on the mass of the carrier alumina.

[0040] In step (2), after the sulfur conversion reaction, the material in the second adsorption zone is contacted with sulfur adsorbent II to adsorb and remove H2S, and the reaction conditions include: temperature of 250-350°C, pressure of 0.3-1.0 MPa, volume space velocity of 4-12 h -1 , and hydrogen / hydrocarbon molar ratio of 0.1-3. The sulfur adsorbent II includes an inorganic oxide carrier and a metal oxide supported on the inorganic oxide carrier, the inorganic oxide carrier is Al2O3 and / or SiO2, and the metal oxide is an oxide of an alkali metal and / or an alkaline earth metal; the alkali metal is Na or K, and the alkaline earth metal is Ca or Mg; the mass fraction of the metal in the metal oxide is 10-20% based on the mass of the inorganic oxide carrier, and preferably the sulfur adsorbent II is K2O / Al2O3-SiO2 or CaO / Al2O3-SiO2. The sulfur adsorbent II can be packed in two vessels, which can be connected in series or in parallel, and one of the vessels can be removed for regeneration or replacement of the adsorbent.

[0041] In step (2), after the first adsorption, sulfur conversion and second adsorption, the material is dehydrated by a feed dryer to obtain a second material before entering the aromatization reactor. The feed dryer includes a bed layer containing activated alumina and molecular sieve, and the molecular sieve is preferably 4A and / or 5A molecular sieve. The feed dryer can include a single vessel or two vessels, which can be connected in series or in parallel, and one of the vessels can be removed for regeneration or replacement, and the use temperature of the feed dryer is 20-50°C, the pressure is 0.3-1.0 MPa, and the volume space velocity is 2-10 h -1 .

[0042] The second material is obtained after steps (1) and (2). In the second material, the normal alkanes and / or single-methyl alkanes in C6-C8 alkanes have low octane number, which are converted into aromatic hydrocarbons and high-octane dimethyl / multi-methyl alkanes by contacting with an aromatization catalyst in step (3). The high-octane dimethyl / multi-methyl alkanes can be 2,2-dimethylbutane, 2,3-dimethylbutane, 2,3-dimethylpentane, 2,3-dimethylpentane, 2,2,3-trimethylbutane, etc.

[0043] When the sulfur and water contents in the second material meet the required standards, i.e., the sulfur content is lower than 0.1 ppm and the water content is lower than 1 ppm, the second material can be mixed with hydrogen for the alkanes aromatization reaction in step (3).

[0044] In step (3), the second material is subjected to aromatization reaction with hydrogen in the presence of a zeolite catalyst comprising L-zeolite and platinum supported thereon. The L-zeolite catalyst has high aromatization reactivity and aromatic selectivity, and can convert alkanes with low octane number in the raw material into aromatic hydrocarbons, while producing highly branched alkanes with high octane number.

[0045] The L-zeolite can be prepared by the following method comprising:

[0046] (a) mixing inorganic base, aluminum source, silicon source and water to obtain a reaction mixture gel, wherein the molar ratio of the substances in the reaction mixture gel is (2.0-4.0) inorganic base: Al203: (5-20) Si02: (60-300) H20; a directing agent can also be used, and the composition of the directing agent is (5-10) K20: Al203: (26-40) Si02: (300-600) H20, and the inorganic base is selected from potassium hydroxide or a mixture of potassium hydroxide and sodium hydroxide;

[0047] (b) subjecting the reaction mixture gel to static hydrothermal crystallization at 100-200°C for 10-120 hours, with at least one intermittent stirring during the crystallization, and the intermittent stirring time is 0.1-3.0 hours, and then washing and drying the solid after the crystallization.

[0048] The step (a) is the preparation of the reaction mixture gel, and the order of adding the raw materials is not particularly limited during the preparation, and the preferred order of adding the raw materials is: adding the aluminum source into the inorganic base solution to form an inorganic base-containing aluminum sol, then mixing the silicon source uniformly to form the reaction mixture gel, and then adding the directing agent into the reaction mixture gel.

[0049] The molar ratio of the substances in the reaction mixture gel is preferably (2.3-3.0) inorganic base: Al203: (7-12) Si02: (100-200) H20, wherein the amount of the inorganic base is calculated based on the alkali metal oxide contained therein, the amount of aluminum is calculated based on Al203, and the amount of silicon is calculated based on Si02.

[0050] The amount of the directing agent is calculated based on Al203, and the molar ratio of Al203 in the added directing agent to Al203 in the synthesis raw materials (excluding the directing agent) is 1-10%, preferably 3-8%.

[0051] The directing agent can be directly added into the mixture gel formed by the inorganic base, aluminum source, silicon source and water, or can be added into the aluminum sol or silicon sol first, and then mixed with other raw materials to form the reaction mixture gel.

[0052] The preparation method of the directing agent can be: mixing an aluminum source, a silicon source, an inorganic base and water in a molar ratio of (5-10)K2O:Al2O3:(26-40)SiO2:(300-600)H2O, preferably mixing an aluminum source, a silicon source, an inorganic base and water in a molar ratio of (6-9)K2O:Al2O3:(26-35)SiO2:(300-470)H2O. The preferable order of adding the materials is: dissolving the aluminum source in an alkali solution, then slowly adding the alkali solution to a silica sol, stirring to form a white gel, and then aging at 25-35°C for 24-72 hours to obtain a translucent sol, which is the crystallization directing agent.

[0053] The step (b) of the method for preparing the L zeolite is the hydrothermal crystallization of the reaction mixture gel. The hydrothermal crystallization process is mainly static crystallization, and at least one intermittent stirring is carried out during the process. The time of the intermittent stirring is preferably 0.5-2.0 hours.

[0054] If the intermittent stirring is once, the intermittent stirring is preferably started from 0-30 hours of static hydrothermal crystallization, more preferably from 5-26 hours of static hydrothermal crystallization.

[0055] If the intermittent stirring is twice, the first intermittent stirring is started from 0-30 hours of static hydrothermal crystallization, preferably from 5-26 hours of static hydrothermal crystallization, and the second intermittent stirring is separated from the first intermittent stirring by 20-50 hours.

[0056] The hydrothermal crystallization temperature is preferably 120-180°C. The hydrothermal crystallization time can be 10-120 hours, preferably 40-80 hours. After the crystallization reaction, the obtained solid product is washed and dried to obtain the L zeolite of the present application. The drying temperature is preferably 80-120°C, and the time is preferably 4-14 hours. The dried L zeolite can also be calcined, and the calcination temperature can be 300-650°C, preferably 300-450°C.

[0057] In the above method, the aluminum source is selected from at least one of aluminum hydroxide and sodium metaaluminate, and the silicon source is selected from at least one of solid silica gel and silica sol, preferably silica sol. The content of SiO2 in the silica sol is 20-45 mass%, preferably 25-40 mass%.

[0058] The L zeolite provided by the present application can also be subjected to ion exchange of K+ in the channel with alkali metal or alkaline earth metal ions. + The method is to exchange the L zeolite with a salt solution containing alkali metal or alkaline earth metal ions, and then dry and calcine. The drying temperature after the exchange is preferably 100-120°C, and the time is preferably 10-15 hours. The calcination temperature is preferably 450-650°C, and the time is preferably 2-4 hours.

[0059] The preparation method of the zeolite catalyst can be directly loading active component platinum in L zeolite and then shaping into a catalyst, or shaping first and then loading active component platinum to prepare a catalyst. The shaping method can be drop ball shaping, rolling ball shaping, extrusion strip shaping or tablet shaping. The method for loading active component is preferably impregnation, i.e. impregnating L zeolite or shaped L zeolite with a solution containing platinum compounds, the impregnation temperature is preferably 15-40℃, more preferably 20-30℃, the liquid / solid volume ratio during impregnation is preferably 0.2-6:1, preferably 0.4-0.8, and the time is preferably 2-10 hours. The obtained solid after impregnation is dried and calcined to obtain the catalyst. The drying temperature is preferably 80-120℃, more preferably 100-120℃, and the time is preferably 8-20 hours; the calcination temperature is 300-600℃, preferably 350-450℃, and the time is preferably 2-8 hours.

[0060] The platinum-containing compound is chloroplatinic acid, amine chloroplatinic acid, dichlorotetrakisammonium platinum or dinitrodiamino platinum.

[0061] The zeolite catalyst needs to be reduced before contacting with raw oil. The reduction preferably uses hydrogen as the reducing gas, the reduction temperature is 350-550℃, preferably 400-500℃, the volume ratio of hydrogen to catalyst during reduction is 300-1000:1, preferably 400-800:1, and the time is preferably 1-10 hours.

[0062] In the platinum-loaded L zeolite, the content of platinum is 0.5-2.0% by mass based on the L zeolite, and the content of W heterocrystal in the L zeolite is less than 0.3% by mass, wherein the content of W heterocrystal is calculated by the ratio of the peak intensity of the characteristic peak 2θ=12.6° of W zeolite and the characteristic peak 2θ=22.7° of L zeolite in the XRD pattern of the zeolite.

[0063] In the method of the present application, the alkane aromatization reaction is carried out under the reaction conditions of 430-550℃, 0.1-2.0 MPa, volume space velocity 0.5-10 h -1 , and hydrogen / alkane molar ratio 0.1-10. Preferably, the reaction conditions are 450-520℃, 0.3-1.0 MPa, hydrogen / alkane molar ratio 3-6, and volume space velocity 1.0-5.0 h -1 , more preferably 1.0-2.0 h -1 . After separating aromatic hydrocarbons from the aromatization reaction product, the obtained non-aromatic hydrocarbons are high-octane isomeric alkanes rich in dimethyl alkanes, which can be used as a blending gasoline to improve the quality of gasoline.

[0064] In the method of the present application, the aromatization reaction product is subjected to gas-liquid separation to separate hydrogen, a small amount of methane and ethane gas product, which can be used in three parts. One part can be used as the recycle hydrogen of the aromatization reaction, one part can be used as the hydrogen source of the pre-hydrogenation reaction, and the other part can be used as the recycle hydrogen of the aromatization reaction, and the excess part can be discharged from the reaction system as the hydrogen source for other device unit operations. The separated hydrogen as the recycle hydrogen of the aromatization reaction must be subjected to dehydration and drying in a gas dryer, which includes a bed layer containing activated alumina and molecular sieve, and the molecular sieve is preferably 4A and / or 5A molecular sieve. The gas dryer can include a single container, or two containers, which can be used in series or in parallel, and one of the containers can be cut off for regeneration and replacement of the drying agent, the use temperature of the gas dryer is 20-50℃, the pressure is 0.3-1.0 MPa, and the volume space velocity is 2-10h -1 .

[0065] In the method of the present application, a supplementary hydrogen line can also be provided, which has three purposes, one is to provide reducing hydrogen for in-situ reduction of the aromatization catalyst, the second is to provide supplementary hydrogen for the aromatization reaction to assist in removing impurities in the recycle gas of the aromatization reaction unit, and the third is to provide supplementary hydrogen required by the sulfur adsorbent and sulfur conversion agent. If the reducing gas for the aromatization catalyst or the supplementary hydrogen for the aromatization reaction must be subjected to dehydration and drying in a gas dryer, which includes a bed layer containing activated alumina and molecular sieve, and the molecular sieve is preferably 4A and / or 5A molecular sieve. The feed dryer is preferably selected to have two containers, which can be used in series or in parallel, and one of the containers can be cut off for regeneration and replacement of the drying agent, the use temperature of the gas dryer is 20-50℃, the pressure is 0.3-1.0 MPa, and the volume space velocity is 2-10h -1 .

[0066] In the method of the present application, the aromatization reaction product is first subjected to gas-liquid separation to obtain a liquid phase material, i.e., hydrogen is first separated out in a high-pressure gas-liquid separator, and then liquefied gas (C4 and hydrocarbons with carbon number less than 4) fraction is separated out in a stabilizer column, and the remaining liquid phase material can be subjected to aromatic extraction to separate aromatic hydrocarbons and non-aromatic hydrocarbons, the extracted oil is the aromatic hydrocarbon component, and the raffinate oil is the non-aromatic hydrocarbon component, i.e., isomerized alkanes gasoline. Preferably, C5 in the liquid phase material is first separated out as a high-octane gasoline component, and then C6 and components with carbon number greater than 6 are subjected to aromatic extraction. The non-aromatic hydrocarbon component obtained by aromatic extraction can be directly used as isomerized alkanes gasoline, or can be returned in whole or in part as the raw material for the aromatization reaction, or dimethyl alkanes in the non-aromatic hydrocarbon component are separated out, and the remaining components are returned as the raw material for the aromatization reaction.

[0067] In the process of the present application, the dimethylalkanes in the liquid phase material can be separated first, and the rest of the components are subjected to aromatic extraction to obtain aromatics and non-aromatics, and the non-aromatic components are returned as raw materials for aromatization reaction or as isomeric alkane gasoline.

[0068] In the process of the present application, the separation of C5 and dimethylalkanes can be carried out by conventional rectification.

[0069] The present application will be further described below by referring to the flow chart shown in Figure 1

[0070] Figure 1 ​In the process, the C6-C8 alkane feedstock rich in n-alkanes and / or monomethylalkanes is pressurized by feed pump 2 via line 1, then mixed with hydrogen from line 44 via line 3, heated to reaction temperature by heat exchanger 4 with the prehydrogenation reaction product, then enters the prehydrogenation reactor 8 via line 5 from the top, the reaction product is discharged via line 9, and the feedstock is exchanged by heat exchanger 4, then enters the cooler 11 via line 10 after being cooled, and then enters the high-pressure gas-liquid separator 13 via line 12. The gas separated by the high-pressure gas-liquid separator 13 is mainly composed of hydrogen, which is discharged from the device via line 14. The liquid product separated from the high-pressure gas-liquid separator 13 enters the dehydration column 16 via line 15, the overhead material is separated and discharged outside the device via line 17 after further cooling, and the column bottom material enters the sulfur protection bed 19 via line 18. The material is obtained from the first material from the top to the bottom, the first material enters the first adsorption zone 21 containing sulfur adsorbent I via line 20, and the material passes from the bottom to the top. In addition, the first material before the first adsorption zone can be mixed with hydrogen from line 75 in line 20 and enter the first adsorption zone 21. The material passing through the first adsorption zone 21 is mixed with hydrogen from line 76 after being heated via line 22 and then enters the sulfur conversion reactor 23, and then the product enters the second adsorption zone 25 containing sulfur adsorbent II via line 24 and passes from the bottom to the top. The material after dehydration and drying enters the high-pressure gas-liquid separator 29 via line 28 for gas-liquid separation, and the gas separated by the high-pressure gas-liquid separator 29 is discharged from the device via line 30. The liquid product separated from the high-pressure gas-liquid separator 29 is detected and analyzed for sulfur content and water content. If the requirements for the aromatization reaction feedstock are not met, it is discharged outside via line 31 to the unqualified line; if the sulfur and water contents meet the requirements for the aromatization reaction feedstock, it is marked as the second material, which enters the aromatization reaction feed pump 32 via line 31. After being pressurized by the feed pump 32, it is mixed with hydrogen from line 51 via line 33, exchanged with the aromatization reaction product by heat exchanger 34, heated to reaction temperature by heat exchanger 36 via line 35, enters the aromatization reaction zone 38 from the top via line 37, which is generally composed of four to six reactors connected in series, and an intermediate heater is provided between every two reactors to compensate for the endothermic reaction of alkane reforming. The reaction product is discharged via line 39, exchanged with the feedstock by heat exchanger 34, cooled by cooler 41 via line 40, and then enters the high-pressure gas-liquid separator 43 for gas-liquid separation via line 42.The gas separated by the high pressure gas-liquid separator 43, which is mainly composed of hydrogen, can be used in two ways. One part of the gas is introduced into line 3 via line 44 to serve as the hydrogen source for the pre-hydrogenation reaction. The other part of the gas is circulated in the aromatization reaction system, is pressurized by compressor 47 via line 46 from line 44, is introduced into line 48, and then is introduced into gas dryer 49. After drying, the gas is introduced into line 34 via lines 50 and 51 to mix with the aromatization reaction feed and to provide the hydrogen source for the aromatization reaction of alkanes. The excess gas can be discharged from the device via line 44 to line 45 to be used in other devices. The liquid product separated from the high pressure gas-liquid separator 43 is introduced into stabilizer column 53 via line 52. The overhead material of stabilizer column 53 is cooled by cooler 55, is introduced into overhead reflux tank 57 via line 56, and the tank bottom liquid petroleum gas is combined with the liquid petroleum gas separated from the stabilizer column side line via line 60. The combined liquid petroleum gas is discharged from the device via line 59, and the overhead fuel gas is discharged from the device via line 58. The stabilizer column 53 bottom product is introduced into depentanizer 62 via line 61. The depentanizer 62 overhead product is introduced into overhead reflux tank 66 via line 63, cooler 64 and line 65. The pentane is discharged from the device via line 68 as a gasoline blending component, and the fuel gas is discharged from the device via overhead line 67. The liquid petroleum gas separated from the depentanizer side line is discharged from the device via line 69 to line 68. The C6 and C6+ components obtained from the depentanizer 62 bottom are introduced into aromatic extraction distillation device 71 via line 70. After aromatic extraction distillation, the separated aromatic hydrocarbons are discharged from the device as aromatic products via line 73, and the non-aromatic components (aromatic raffinate) are discharged from the device as isomeric naphtha gasoline via line 72, which can be used as a gasoline blending component. The device also needs to be provided with a supplemental hydrogen line to supply supplemental hydrogen to the aromatization reaction unit and the deep refining desulfurization and dehydration unit. The supplemental hydrogen is divided into two parts. One part is introduced into line 75 via line 74 to provide the hydrogen source for the first sulfur adsorption zone, and the other part is introduced into line 76 via line 74 to provide the hydrogen source for the sulfur conversion reactor. The other part of the supplemental hydrogen is introduced into gas dryer 78 via line 77, is introduced into line 37 via line 51, and is introduced into the aromatization reaction zone to provide supplemental hydrogen for the aromatization reaction.

[0071] The application will be further described by examples, but the application is not limited to the examples.

[0072] Example 1

[0073] This example illustrates the preparation of the aromatization reaction catalyst used in the application.

[0074] (1) Preparation of L zeolite

[0075] An aluminasol was prepared by adding 12.08 g of Al(OH)3 (produced by China Aluminum Co., Ltd., trade name H-WF-10, hereinafter the same) to a solution containing 77.57 g of KOH (purity 85.7 mass%, hereinafter the same) in an amount of 264.12 ml, and heating to dissolve. The aluminasol was added to 435.6 g of a silicasol (containing 30 mass% of SiO2, pH 9, hereinafter the same) which had been preheated to 50°C, with stirring for 0.5 hour to form a white gel. The white gel was aged at 30°C for 72 hours to obtain a translucent sol which was a crystallization directing agent.

[0076] An aluminasol was prepared by adding 107.08 g of Al(OH)3 to a solution containing 211.24 g of KOH in an amount of 1124.53 ml, and heating to dissolve. The aluminasol was added to a reaction vessel containing 1198.61 ml of a silicasol, with stirring for 0.5 hour to form a white reaction mixture gel, the molar composition of which was 2.7 K2O: Al2O3: 10 SiO2: 180 H2O.

[0077] The white gel was warmed to 150°C with stirring, and the stirring was stopped to perform a first static crystallization for 24 hours. Then, a first stirring crystallization was performed for 1 hour, and a second static crystallization was performed for 47 hours. The crystallization product was rapidly cooled to 40°C, and was separated by centrifugation. The upper liquid was removed, and the solid was washed with deionized water until the pH of the liquid phase was 9 to 10. The obtained solid was dried at 120°C for 10 hours to obtain L-zeolite raw powder a, the chemical composition of which was 1.22 K2O: Al2O3: 5.56 SiO2, the relative crystallinity was 98.6, the W impurity crystal was 0.03 mass%, and the average crystal size was 0.6 μm.

[0078] (2) Preparation of Catalyst

[0079] 100 g of the L-zeolite raw powder a prepared in (1) was impregnated with a Pt(NH3)4Cl2 solution having a concentration of 15.7 mg / ml at 30°C for 12 hours, the impregnation liquid / solid volume ratio being 1.5:1. The impregnated solid was dried at 120°C for 12 hours, and was calcined at 350°C for 4 hours to obtain an aromatization reaction catalyst, the Pt content of which was 1.0 mass% (calculated on the basis of the L-zeolite).

[0080] Example 2

[0081] This example illustrates the preparation of the sulfur adsorbent I used in the present application.

[0082] Take 30 grams of NiO powder, 10 grams of MnO2 powder, 50 grams of aluminum hydroxide powder (wherein the Al2O3 content is about 76 mass%), 20 grams of diatomite and 2 grams of sesbania powder, mix and grind uniformly, take 1 milliliter of 65 mass% nitric acid, 2 milliliters of 36% acetic acid, add to 70 milliliters of water to dissolve to obtain a peptizing agent solution, then add the solution to the above mixed powder, mix and knead uniformly, then extrude into strips, dry the wet strips at 120°C for 12 hours, calcine at 500°C for 4 hours, to obtain sulfur adsorbent I, wherein the NiO content is 30 mass%, the MnO2 content is 10 mass%, the SiO2 content is 20 mass%, and the Al2O3 content is 40 mass%, based on the sulfur adsorbent.

[0083] Example 3

[0084] This example illustrates the preparation of a sulfur conversion agent for use in the present application.

[0085] Take 100 grams of aluminum hydroxide powder prepared by the alkoxy hydrolysis method (wherein the Al2O3 content is about 76 mass%), mix and knead the pseudoboehmite powder uniformly according to the mass ratio of powder: sesbania powder: 65% nitric acid: 36% acetic acid: citric acid: water = 50:1:1:2:3:40, then extrude into strips, dry the wet strips at 120°C for 12 hours, and calcine at 550°C for 4 hours to obtain a γ-Al2O3 carrier.

[0086] Take 30 grams of γ-Al2O3 carrier, prepare an impregnation solution by mixing chloroplatinic acid, palladium chloride and hydrochloric acid, so that the Pt content in the impregnation solution is 0.2 mass%, the Pd content is 0.1 mass%, and the Cl content is 1.8 mass% (relative to the mass of dry base alumina), and the liquid / solid volume ratio is 1.5. After impregnation at normal pressure and room temperature for 3 hours, dry to dryness under reduced pressure at 70°C and 0.008 MPa, then dry at 120°C for 12 hours, calcine in air atmosphere at 500°C with a gas / adsorbent volume ratio of 700 for 4 hours, cool to 150°C, replace with nitrogen, then replace with hydrogen, then reduce with hydrogen at 400°C with a gas / adsorbent volume ratio of 500 for 2 hours to obtain a sulfur conversion agent, wherein the Pt content is 0.2 mass% and the Pd content is 0.5 mass%, based on the dry base alumina.

[0087] Example 4

[0088] This example illustrates the preparation of a sulfur adsorbent II for use in the present application.

[0089] Take 92 grams of aluminum hydroxide powder prepared by the alkoxy hydrolysis method (wherein the Al2O3 content is about 76 mass%) and 30 grams of silicon oxide powder, mix and knead the powders uniformly according to the mass ratio of powder: sesbania powder: 65% nitric acid: 36% acetic acid: citric acid: water = 50:1:1:2:3:40, then extrude into strips, dry the wet strips at 120°C for 12 hours, and calcine at 650°C for 4 hours to obtain an Al2O3-SiO2 carrier.

[0090] Take 30 grams of Al2O3-SiO2carrier, potassium chloride is prepared into impregnation solution, so that the K content in the impregnation solution is 12.5 mass% (relative to the mass of dry base alumina), and the liquid / solid volume ratio is 1.5. After impregnation at normal pressure and room temperature for 3 hours, drying to dry state under reduced pressure at 70°C and 0.008 MPa, then drying at 120°C for 12 hours, and calcining in air atmosphere at 450°C and a gas / agent volume ratio of 700 for 4 hours, the sulfur adsorbent II is obtained, wherein the K2O content is 15 mass% based on the dry base carrier.

[0091] Example 5

[0092] This example illustrates the preparation of the sulfur protection agent used in the present application.

[0093] Take 30 grams of Al2O3carrier in Example 3, prepare copper nitrate into impregnation solution, so that the CuO content in the impregnation solution is 15 mass% (relative to the mass of dry base alumina), and the liquid / solid volume ratio is 1.5. After impregnation at normal pressure and room temperature for 3 hours, drying to dry state under reduced pressure at 70°C and 0.008 MPa, then drying at 120°C for 12 hours, and calcining in air atmosphere at 450°C and a gas / agent volume ratio of 700 for 4 hours, the sulfur protection agent is obtained, wherein the CuO content is 15 mass% based on the sulfur protection agent.

[0094] Example 6

[0095] This example illustrates the method for producing aromatic hydrocarbon and isomeric alkanes gasoline according to the present application.

[0096] The process flow of Figure 1 is used.

[0097] Take raw material 1 shown in Table 1 as the reaction raw material, the S content of raw material 1 is 90 ppm, the H2O content is 230 ppm, fill the industrial grade RS-20 pre-hydrogenation catalyst (RS-20 pre-hydrogenation catalyst composition: WO3: 25.0 mass%; NiO: 2.5 mass%, CoO: 0.07 mass%) in the pre-hydrogenation reactor 8, fill the sulfur protection agent prepared in Example 5 in the sulfur protection bed 19, fill the sulfur adsorbent I prepared in Example 2 in the first adsorption zone 21 reactor, fill the sulfur conversion agent prepared in Example 3 in the sulfur conversion reactor 23, fill the sulfur adsorbent II prepared in Example 4 in the second adsorption zone 25 reactor, fill a small amount of active alumina and 5A molecular sieve in the mass ratio of 1:10 in the feed dryer 27, fill active alumina and 4A molecular sieve in the mass ratio of 1:5 in the make-up hydrogen dryer 78 and the circulating gas dryer 49, and fill the Pt / KL alkane aromatization catalyst prepared in Example 1 in the aromatization reactor 38.

[0098] Before the oil is introduced, the alkane aromatization catalyst needs to be reduced in situ. First, the entire system is sequentially purged with nitrogen, then with hydrogen, and sealed. Next, the aromatization reaction zone is isolated from the pre-hydrogenation reaction zone and the desulfurization and dehydration zone. Hydrogen is introduced into the aromatization reaction zone through hydrogen supply line 77, dryer 78, and line 51. The aromatization catalyst is reduced in situ using a single-pass hydrogen flow method, with a hydrogen-to-catalyst volume ratio of 600:1. Then, the temperature is raised to 480℃ for 2 hours of reduction. After reduction, the temperature is lowered to 370℃, awaiting qualified feedstock.

[0099] Start the hydrorefining feed pump and follow the instructions. Figure 1 The process flow involves the raw materials sequentially passing through a pre-hydrogenation refining unit, a dehydration tower, and a staged refining and deep desulfurization / dehydration unit.

[0100] The pre-hydrogenation reaction was carried out at a temperature of 280℃, a pressure of 2.0 MPa, and a volume hourly space velocity of 6 h⁻¹. -1 The hydrogen / hydrocarbon molar ratio is 0.5.

[0101] The dehydration tower operates at a pressure of 0.80 MPa, with a top temperature of 80°C and a bottom temperature of 200°C.

[0102] The temperature of the sulfur protective agent bed is 140℃, and the volume hourly space velocity is 6h. -1 After passing through the sulfur protection agent bed, the sulfur content in the first material is 0.4 ppm, the H2O content is 4.0 ppm, the nitrogen content is 0.4 ppm, the As content is <1 Ppb, the Hg content is <1 ppb, the Cu content is 8 ppb, the Pb content is 6 ppb, and the Si content is 0.5 ppm.

[0103] The temperature in the first adsorption zone is 150℃, the reaction pressure is 0.5MPa, and the volume hourly space velocity is 10h⁻¹. -1 The hydrogen-to-hydrogen molar ratio is 0.3;

[0104] The sulfur conversion zone temperature was 350℃, the reaction pressure was 0.5MPa, and the volume hourly space velocity was 10h⁻¹. -1 The hydrogen / hydrocarbon molar ratio is 1.

[0105] The temperature in the second adsorption zone is 300℃, the reaction pressure is 0.5MPa, and the volume hourly space velocity is 6h⁻¹. -1 The hydrogen / hydrocarbon molar ratio is 1.

[0106] The feed dryer temperature is 40℃, the pressure is 0.5MPa, and the volumetric hourly space velocity is 3h⁻¹. -1 .

[0107] The reactants were pumped into the aromatization reaction zone, and then the aromatization reactor was heated to 480°C. The reaction was carried out at 480°C, 0.7 MPa, a hydrogen / hydrocarbon molar ratio of 3, and a volume hourly space velocity of 3 h⁻¹. -1The reaction was carried out under the following conditions. The reaction products were separated into gas and liquid. After removing pentane from the liquid product, aromatics were extracted. The extraction solvent was sulfolane. The extraction tower pressure was 0.05 MPa and the tower top temperature was 88 °C. The raffinate was isoparaffin gasoline, which can be used as a gasoline blending component. The reaction results are shown in Table 2.

[0108] The service life of sulfur adsorbent I is 16,800 hours, the service life of sulfur adsorbent II is 16,800 hours, the service life of sulfur protectant is 8,000 hours, and the service life of desiccant in the feed dryer is 240 hours.

[0109] Example 7

[0110] The reaction was carried out according to the method of Example 6, except that the raw material used was raw material 2 as shown in Table 2, and the reaction results are shown in Table 2.

[0111] Table 1

[0112]

[0113]

[0114] Comparative Example 1

[0115] Adopted with the present invention Figure 1 A similar process was used, the difference being the absence of sulfur protectant tank 19. Raw material 1 was used for the alkane aromatization reaction. The sulfur and water contents of the preliminarily dehydrated material, the first material, and the second material are shown in Table 1. The aromatization reaction results are shown in Table 2.

[0116] The service life of sulfur adsorbent I is 8000h, the service life of sulfur adsorbent II is 8000h (without sulfur protectant), and the service life of the desiccant in the feed dryer is 240h.

[0117] It is evident that the service life of sulfur adsorbent I and sulfur adsorbent II is significantly shortened, and the yields of C5+ and aromatics decrease significantly after 100 hours of reaction.

[0118] Comparative Example 2

[0119] Adopted with the present invention Figure 1 A similar process was used, except that dehydration tower 16 was not included, and raw material 1 was used for the alkane aromatization reaction. The sulfur and water contents of the pre-dehydrated material, the first material, and the second material are shown in Table 1. The aromatization reaction results are shown in Table 2.

[0120] The service life of sulfur adsorbent I is 7500h, the service life of sulfur adsorbent II is 7500h, the service life of sulfur protectant is 2500h, and the service life of desiccant in feed dryer is 10h.

[0121] It is evident that the service life of sulfur adsorbent I, sulfur adsorbent II, and sulfur protectant is significantly shortened, the feed desiccant also fails quickly, and the water content of the second material does not meet the requirement of the feed index being less than 1 ppm. After 100 hours of reaction, the yields of C5+ and aromatics decrease significantly.

[0122] Comparative Example 3

[0123] Adopted with the present invention Figure 1 A similar process was used, except that a feed dryer 27 was not installed, and raw material 1 was used for the alkane aromatization reaction. The results of the aromatization reaction are shown in Table 2.

[0124] The service life of sulfur adsorbent I is 16,800 hours, the service life of sulfur adsorbent II is 16,800 hours, and the service life of sulfur protectant is 8,000 hours.

[0125] It is evident that the water content in the second material is 5.1 ppm, which is significantly higher than that in Example 1, failing to meet the requirement of the feed index being below 1 ppm. After 100 h of reaction, the yields of C5+ and aromatics decreased significantly.

[0126] Table 2

[0127]

[0128]

Claims

1. A process for the production of aromatic and isomeric alkanes gasoline characterized in that Comprise: C6~C8 alkane raw material rich in normal alkane and / or single branched alkane is treated by hydrogenation desulfurization and denitrification, dehydration, fractional desulfurization, dehydration and alkane aromatization reaction to obtain aromatic hydrocarbon and isomeric alkane gasoline; in the fractional desulfurization, dehydration, the material treated by hydrogenation desulfurization and denitrification, dehydration is sequentially treated by first adsorption, sulfur conversion and second adsorption, and a dehydration step is arranged after the second adsorption to make the water content less than 1 ppm, the method comprises: (1) hydrogenation desulfurization and denitrification, dehydration: C6~C8 alkane raw material rich in normal alkane and / or single branched alkane is treated by hydrogenation pretreatment and dehydration after being contacted with hydrogen to obtain preliminary dehydration material, and then contacted with a sulfur protective agent to obtain first material, the sulfur content and nitrogen content in the preliminary dehydration material is not higher than 2 ppm, and the H2O content is not higher than 50 ppm, the sulfur content and nitrogen content in the first material is not higher than 0.5 ppm, and the H2O content is not higher than 20 ppm; (2) fractional desulfurization and dehydration: the first material in step (1) is contacted with sulfur adsorbent I for first adsorption, then contacted with sulfur conversion catalyst, then contacted with sulfur adsorbent II for second adsorption, and finally dried and dehydrated to obtain second material with sulfur content less than 0.1 ppm and water content less than 1 ppm, the sulfur adsorbent I is bimetallic adsorbent, the sulfur adsorbent I contains first metal component and second metal component, the first metal component is selected from nickel or copper, and the second metal component is selected from manganese or titanium; the sulfur conversion catalyst is organic sulfur conversion inorganic sulfur catalyst containing Group VIII metal and metal potassium; the sulfur adsorbent II is adsorbent containing alkali metal and / or alkaline earth metal metal oxide; (3) alkane aromatization reaction: the second material in step (2) is subjected to aromatization reaction with hydrogen under zeolite catalyst, and the product is separated into aromatic hydrocarbon component and non-aromatic hydrocarbon component, the non-aromatic hydrocarbon component is isomeric alkane gasoline, and the zeolite catalyst comprises L zeolite and platinum supported thereon.

2. The method of claim 1, wherein, The sulfur protecting agent of step (1) comprises a carrier and an active component supported thereon, the carrier is AI2O3, the active component is selected from one of copper oxide, zinc oxide, activated carbon, molecular sieve, the content of the active component is 15-50 mass% based on the mass of the sulfur protecting agent, the contact temperature is 40-200°C, the volume space velocity is 4-20h -1 .

3. The method of claim 1, wherein, The sulfur content in the first material is 0.2~0.5 ppm, and the water content is 5~20 ppm.

4. The method of claim 1, wherein, The first material in step (2) is contacted with the sulfur adsorbent I for first adsorption, and the reaction conditions include: the temperature is 120℃-200℃, the pressure is 0.3-1.0 MPa, the volume space velocity is 4-20 h -1 , and the hydrogen / hydrocarbon molar ratio is 0-1.

5. The method of claim 1, wherein, The reaction conditions for the step (2) of contacting with the sulfur conversion catalyst include: temperature of 250-400℃, pressure of 0.3-1.0 MPa, volume space velocity of 4-12 h -1 , and hydrogen / hydrocarbon molar ratio of 0.1-3.

6. The method of claim 1, wherein, The second adsorption by contacting with the sulfur adsorbent II in step (2) has the reaction conditions including: the temperature is 250-350℃, the pressure is 0.3-1.0MPa, the volume space velocity is 4-12h -1 , and the hydrogen / hydrocarbon molar ratio is 0.1-3.

7. The method of claim 1, wherein, The reaction conditions of the aromatization reaction in step (3) include: temperature of 430-550℃, pressure of 0.1-2.0 MPa, hydrogen / hydrocarbon molar ratio of 0.1-10, volume space velocity of 0.5-10.0 h -1 .

8. The method of claim 1, wherein, The sulfur adsorbent I in step (2) comprises carrier and two kinds of metal oxides supported on the carrier, the carrier comprises Al2O3 and SiO2, the first kind of metal oxide is selected from NiO or CuO, and the second kind of metal oxide is selected from MnO2 or TiO2; The mass ratio of the first kind of metal oxide to the mass of the sulfur adsorbent I is 20~50%, the mass ratio of the second kind of metal oxide is 5~15%, the mass ratio of SiO2 is 5~20%, and the mass ratio of Al2O3 is 15~70%.

9. The method of claim 1, wherein, The sulfur conversion catalyst in step (2) comprises carrier alumina and Group VIII metal and metal K supported on the carrier alumina, the Group VIII metal is Pt and / or Pd; the mass ratio of the Group VIII metal to the mass of the carrier alumina is 0.2~2%, and the mass ratio of metal K is 0~0.5%.

10. The method of claim 1, wherein, The sulfur adsorbent II in step (2) comprises an inorganic oxide carrier and a metal oxide supported on the inorganic oxide carrier, the inorganic oxide carrier is Al2O3 and / or SiO2, and the metal oxide is an oxide of an alkali metal and / or an alkaline earth metal; the alkali metal is Na or K, and the alkaline earth metal is Ca or Mg; the mass fraction of the metal in the metal oxide is 10-20% based on the mass of the inorganic oxide carrier.

11. The method of claim 10, wherein, The sulfur adsorbent II in step (2) is K2O / Al2O3-SiO2 or CaO / Al2O3-SiO2.

12. The method of claim 1, wherein, The platinum content of the zeolite catalyst in step (3) is 0.5-2.0 mass%, and the content of the W hetero crystal in the L zeolite is less than 0.3 mass%, both of which are calculated based on the mass of the L zeolite.

13. The method of claim 1, wherein, The hydrogen used in steps (1) and (2) is from new hydrogen supplement or recycled hydrogen; before being mixed with the alkane material, the new hydrogen supplement is first dehydrated in a make-up gas dryer, and the recycled hydrogen is dehydrated in a recycle gas dryer, so that the water content in the hydrogen is less than 5 ppm.

14. The method of claim 1, wherein, After the aromatization reaction, the reaction product is subjected to gas-liquid separation, and the liquid phase is subjected to aromatic extraction to separate aromatic components and non-aromatic components therefrom.

15. The method of claim 14, wherein, The non-aromatic components are all or partially returned to continue the alkane aromatization reaction.

16. The method according to any one of claims 1 to 15, characterized in that The C6-C8 alkane raw material rich in n-alkanes and / or single branched alkanes contains not less than 50 mass% of n-alkanes and / or single methyl alkanes.

17. The method according to any one of claims 1 to 15, characterized in that The C6-C8 alkane raw material rich in n-alkanes and / or single branched alkanes contains not less than 80 mass% of C6-C7 alkanes.

18. The method according to any one of claims 1 to 15, characterized in that The C6-C8 alkane raw material rich in n-alkanes and / or single branched alkanes is at least one of narrow-cut refined naphtha, reformate, hydrocracking gasoline, aromatic raffinate, Fischer-Tropsch synthesis naphtha and alkylate, and contains 2-500 ppm of S and 20-500 ppm of H2O.

19. The method according to any one of claims 1 to 15, characterized in that The C6-C8 alkane raw material rich in n-alkanes and / or single branched alkanes is C6 alkanes, C7 alkanes, or a mixture of C6 and C7 alkanes or C6, C7 and C8 alkanes, and contains 2-300 ppm of S and 20-300 ppm of H2O.

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