Method for producing light aromatic hydrocarbons

Abstract

A method for producing light aromatic hydrocarbons from C9+ aromatic hydrocarbons includes a step of contacting a C9+ aromatic hydrocarbon with a dealkylation catalyst comprising a KL zeolite, and platinum and a modifying metal supported thereon in the presence of hydrogen, to obtain a light aromatic hydrocarbon. The modifying metal is selected from the group consisting of Group IIA metals and rare earth metals. By using a Pt / KL catalyst comprising a specific modifying metal in the dealkylation reaction of C9+ aromatic hydrocarbons for producing light aromatic hydrocarbons, the method shows the advantages of high conversion rate of feedstock, high yield of light aromatic hydrocarbons, good reaction selectivity. Fig. 1

Description

A method for producing light aromatics

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202110440767.6, filed on April 23, 2021, entitled “A method for producing light aromatic hydrocarbons from naphtha”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of catalytic conversion of aromatic hydrocarbons, specifically to a method for converting C9 + A method for producing light aromatics from aromatics. Background Art

[0004] Naphtha typically contains C6-C12 alkanes, cycloalkanes, and aromatics. The mainstream processing approach involves catalytic reforming and other technologies to convert the alkanes and cycloalkanes into aromatics or high-octane gasoline blending components, while also producing high-value-added hydrogen. The liquid products from the reforming reaction, in addition to light aromatics such as BTX, also contain unconverted light alkanes below C7 and heavy aromatics above C9.

[0005] The main reactions occurring during catalytic reforming include six major categories: dehydrogenation of six-membered cycloalkanes, dehydrogenation and isomerization of five-membered cycloalkanes, isomerization of alkanes, cycloalkanes, and aromatics, dehydrocyclization of alkanes, and hydrogenolysis and hydrocracking of alkanes. Traditional catalytic reforming reaction chemistry follows the principle of converting naphtha components of the same carbon number into products of the same carbon number, with product distribution guided by the laws of chemical thermodynamics and kinetics. Therefore, once the reforming catalyst and process technology are determined, the aromatics yield and product distribution depend on the feedstock composition, while the ratio of benzene, toluene, and xylene isomers, as well as the proportion of heavy aromatics, in the products remain essentially unchanged. Under existing catalyst systems, the scope for manipulating the distribution of individual products by varying reaction conditions is very limited.

[0006] Since the above-mentioned main reforming reactions follow the principle that the carbon number of reactants and products is the same (except for alkane hydrogenolysis and hydrocracking reactions), the content of heavy aromatics above C9 in the reforming oil is relatively high, usually up to 20% by mass or more. Limited by the terminal boiling point of finished gasoline, heavy aromatics cannot all be used as gasoline blending components. Although some heavy aromatics can be sold as products after separation by distillation, the market capacity is limited. The dehydrogenation cyclization reaction rate of C6 and C7 light alkanes is relatively slow, and a method of increasing the severity of the reforming operation is usually adopted to increase its conversion rate. However, increasing the severity has the problem of poor reaction selectivity, aggravation of reactions such as hydrocracking, resulting in a decrease in liquid yield, and the consumption of hydrogen.

[0007] Chinese patent application CN102795958A discloses a method for producing aromatic hydrocarbons and ethylene using naphtha as raw material, comprising: heating naphtha at a pressure of 0.15-3.0 MPa, a temperature of 300-540°C, and a volume space velocity of 2.1-50 h -1 The crude oil is contacted with a reforming catalyst under hydrogen conditions to carry out shallow catalytic reforming reaction, so that the conversion rate of cycloalkanes in naphtha is greater than 85% by mass, and paraffins are converted into aromatics and C4 - The hydrocarbon conversion rate is less than 30% by mass; the reformed oil obtained by catalytic reforming is sent to an aromatics separation unit to separate alkanes from aromatics to obtain an aromatics-rich fraction and a paraffin-rich fraction; the paraffin-rich fraction is sent to a steam cracking unit for cracking reaction to produce ethylene.

[0008] Chinese patent application CN101376823A discloses a naphtha catalytic reforming method, which includes passing naphtha into a reactor of a conventional catalytic reforming device, and separating the reformed product into gas components, C8 - Light components and C9 + Recombination, C9 + The heavy components are subjected to a lightening reaction in the presence of an aromatic lightening catalyst. The reaction temperature of the lightening reaction is preferably 420-530°C, the pressure is 0.8-1.5 MPa, and the liquid feed volume space velocity is preferably 1-10 h -1 , hydrogen / hydrocarbon molar ratio 0.1-10.0. The lightweight catalyst comprises active components iridium, potassium and chlorine, and an alumina carrier. In the embodiment of this patent application, C9 + The conversion rate of heavy aromatics is between 56.90-69.37% by mass, and the mass yield of BTX is between 43.00-54.61%.

[0009] Chinese patent application CN109401785A discloses a naphtha upgrading method, comprising: contacting naphtha with a dehydrogenation catalyst through a first reaction zone and performing a dehydrogenation reaction under dehydrogenation reaction conditions to convert part of the cycloalkanes in the naphtha into aromatics; the dehydrogenation reaction temperature is preferably 380-440°C, the reaction pressure is preferably 0.3-0.6 MPa, and the feed mass space velocity is preferably 4-10 h -1 The gas / oil volume ratio is preferably 200-600. The dehydrogenation catalyst comprises a first support and a chlorine element and a Group VIII metal supported on the first support. The reaction product from the first reaction zone is introduced into a second reaction zone, contacted with a reforming catalyst, and subjected to a reforming reaction. The resulting reaction product is cooled and separated to produce a gaseous product and a liquid product. In the examples of this patent application, the mass yield of the liquid product ranges from 79.15% to 85.95%, and the mass content of aromatics in the liquid product ranges from 28.02% to 36.17%.

[0010] Chinese patent application CN110358577A discloses a method for converting naphtha into high-octane gasoline and aromatics, comprising: heating naphtha at 0.2-2.0 MPa, 350-520°C, and a volume space velocity of 1.0-5.0 h -1 , contact with reforming catalyst under hydrogenation conditions with a hydrogen / hydrocarbon molar ratio of 0.5-20:1 to carry out moderate reforming reaction, so that the conversion rate of cycloalkanes in naphtha is greater than 85% by mass, C8 + The paraffin conversion rate is greater than 50% by mass, and the C6 paraffin conversion rate is not greater than 5% by mass; the reformed oil obtained by the catalytic reforming reaction is subjected to aromatic separation to obtain an aromatics-rich component and a paraffin-rich component, and the paraffin-rich component is cut into a C5-C6 fraction and a C7 + The C5-C6 fraction is contacted with an isomerization catalyst to perform an isomerization reaction, and the isomerization reaction product is reacted with the C7 + The fractions are mixed and contacted with an aromatization catalyst to carry out an aromatization reaction. The aromatization catalyst comprises KL zeolite and 0.1-1.5% by mass of platinum supported thereon based on the KL zeolite.

[0011] Chinese patent CN1231559C discloses a catalytic reforming method for producing an aromatics-rich product using three catalyst zones, comprising catalytically reforming a hydrocarbon feedstock in a process sequence comprising a first dual-functional catalyst reforming zone, a zeolite reforming zone containing a catalyst including a platinum group metal and a non-acidic zeolite, and a final dual-functional catalyst reforming zone. The reaction pressure in the first reforming zone is 100 kPa-1 MPa, and the liquid hourly space velocity is 0.2-20 h -1 , hydrogen and C5 + The molar ratio is 0.1-10, the temperature is 400-560 ° C; the reaction pressure of the second reforming zone is 100kPa-6MPa, the liquid hourly space velocity is 1-40h -1 , temperature is 260-560℃; the reaction pressure in the final reforming zone is 100kPa-1MPa, and the liquid hourly space velocity is 0.2-10h -1 , hydrogen and C5 + The molar ratio is 0.1-10, and the temperature is 400-560° C. In the examples of this patent, a kinetic model is used to simulate the combination of the above two catalysts in four reforming reactors, and the obtained BTX yield is between 45.02% and 49.28%.

[0012] The catalysts for the conversion of heavy aromatics to lighter hydrocarbons reported so far are mainly one or more of the following molecular sieves: ZSM-5, HZSM-5, HY, USY, NaY, β-zeolite, MCM-41, ZSM-12, MOR, NU-87, MFI, etc. These molecular sieves can be used directly or modified using alumina or other oxides as supports. Some catalysts are added with platinum, palladium, iridium or their compounds. The raw material for the reaction is C9 + or C 10 + Heavy aromatics, or C9 heavy aromatics or C 10 Narrower fractions such as heavy aromatics.

[0013] L-type molecular sieve (International Molecular Sieve Association code: LTL) is a basic, large-pore molecular sieve developed by Union Carbide in 1965. To date, no equivalent has been found in nature. Since Bernard (Proc. 5th Int. Conf. on Zeolites, Wiley, New York, 1980, 68) discovered that PtKL exhibits significantly higher activity and selectivity for the aromatization of n-hexane than conventional bifunctional catalysts, platinum-loaded L-type molecular sieves have garnered widespread attention as catalysts for the dehydrogenation and cyclization of normal alkanes. Subsequently, Pt / KL molecular sieve catalysts have achieved industrial application in dehydrogenation and reforming reactions, but the use of such catalysts for the lightweighting of heavy aromatics has been unknown.

[0014] Chinese patent application CN108236964A discloses a bimetallic catalytic reforming catalyst containing LTL molecular sieve, comprising: a catalyst carrier composed of LTL molecular sieve and a binder, and an active component containing a VIIIB group metal, Sn or Re element. The cations in the LTL molecular sieve are partially or completely replaced by lanthanide metal ions. In the embodiment of the patent application, Liaoyang Petrochemical reforming crude oil is used as raw material, and the reaction temperature is 500 ° C, the pressure is 0.5 MPa, and the volume space velocity is 3h -1 , the reaction was carried out for 10 hours under the conditions of hydrogen to oil volume ratio of 800, the aromatics yield was between 60-72%, C5 + The liquid yield is between 80-92%.

[0015] Chinese patent application CN106391098A discloses a naphtha reforming catalyst and its preparation method, wherein the catalyst comprises a carrier, a metal and carbon. By adding a certain amount of monosaccharide during the preparation of the Pt / KL reforming catalyst, the dispersion of the metal Pt is improved and the carbon deposition rate of the catalyst during the reaction is reduced, thereby improving the reforming reaction performance of the Pt / KL catalyst. In the examples of this patent application, catalytic reforming is carried out using Fischer-Tropsch straight-run naphtha as the raw material at a reaction temperature of 500°C, a pressure of 0.7-1.0 MPa, and a volume space velocity of 1.0 h-1 , the reaction was carried out under the condition of hydrogen-to-oil molar ratio of 6, the aromatic yield was between 49.97-74.33%, C5 + The liquid yield was between 71.81-83.04%.

[0016] Summary of the Invention

[0017] The purpose of this application is to provide a method for producing light aromatics. + Aromatics or C9 + Using paraffin as raw material, light aromatics are prepared with high efficiency.

[0018] On the one hand, the present application provides a C9 + A method for producing light aromatic hydrocarbons from aromatic hydrocarbons, comprising: reacting C9 + Aromatic hydrocarbons are contacted with a dealkylation catalyst to undergo a dealkylation reaction to obtain light aromatic hydrocarbons. The dealkylation catalyst comprises KL zeolite and platinum and a modifying metal supported thereon, wherein the modifying metal is selected from Group IIA metals and rare earth metals.

[0019] The above method of the present application is to use a Pt / KL catalyst containing a specific modified metal to form a C9 + The dealkylation reaction of aromatics to produce light aromatics has the characteristics of high raw material conversion rate, high light aromatics yield, and good reaction selectivity.

[0020] On the other hand, the present application provides a method comprising + A method for producing light aromatic hydrocarbons from paraffin raw materials comprises the following steps:

[0021] 1) Include C9 + The paraffinic hydrocarbon raw material is contacted with a dehydrogenation catalyst in the presence of hydrogen in the first reaction zone to react at least part of the C9 + Alkanes undergo dehydrogenation and cyclization to produce C9 + Aromatic hydrocarbons, optionally separating the obtained product to obtain C9 + A stream of aromatic hydrocarbons, wherein the dehydrogenation catalyst comprises alumina and a Group VIII metal, a Group IVA metal, a Group IA metal and a halogen supported thereon;

[0022] 2) Make the product obtained in step 1) contain C9 + The aromatic hydrocarbon stream is contacted with a dealkylation catalyst in the presence of hydrogen in a second reaction zone to dealkylate at least a portion of the C9 + Aromatic hydrocarbons undergo a dealkylation reaction to obtain light aromatic hydrocarbons, wherein the dealkylation catalyst comprises KL zeolite and platinum and a modifying metal supported thereon, wherein the modifying metal is selected from Group IIA metals and rare earth metals.

[0023] The above method of the present application is to+ C9 in paraffinic raw materials + The paraffin undergoes a directional dehydrogenation cyclization reaction in the first reaction zone to obtain C9 + Aromatics, then C9 + Aromatic dealkylation reaction can convert C9 + Paraffins are efficiently converted into light aromatics, such as BTX, to increase their utilization value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The following drawings are used to provide a further understanding of the present application and constitute part of the specification. Together with the following specific embodiments, they are used to explain the present application but do not constitute a limitation of the present application.

[0025] FIG1 is a flow chart of a preferred embodiment of the method of the present application. DETAILED DESCRIPTION

[0026] The following describes the specific embodiments of the present application in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application and are not intended to limit the present application.

[0027] Any specific numerical value disclosed herein (including the endpoints of a numerical range) is not limited to the exact value of the numerical value, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Moreover, for a disclosed numerical range, any combination of the endpoints of the range, between the endpoints and the specific points in the range, and between the specific points can be used to generate one or more new numerical ranges, and these new numerical ranges should also be considered to be specifically disclosed herein.

[0028] Unless otherwise specified, the terms used herein have the same meaning as commonly understood by those skilled in the art. If a term is defined herein and its definition is different from the commonly understood meaning in the art, the definition herein shall prevail.

[0029] In this application, the term "C9 + "Alkanes" refer to straight-chain or branched alkanes with more than 9 carbon atoms, including but not limited to n-nonane, 2-methyloctane, 2,3,5-trimethylhexane, etc.; the term "C9 + "Aromatic hydrocarbons" refer to aromatic hydrocarbons with more than 9 carbon atoms, including but not limited to n-propylbenzene, m-ethylbenzene, 1,3,5-trimethylbenzene, etc.; the term "C7 - The term "alkanes" refers to alkanes having 7 or fewer carbon atoms, including but not limited to n-hexane, 2-methylpentane, 2,3-dimethylpentane, and the like.

[0030] In this application, the term "light aromatics" refers to aromatic hydrocarbons having 6 to 8 carbon atoms, including benzene, toluene, various xylene isomers and ethylbenzene, such as BTX.

[0031] In this application, the term "naphtha" refers generally to various light oil products with a distillation range of 30-220°C obtained from crude oil or other hydrocarbon-containing feedstocks. For example, the naphtha may be straight-run naphtha, hydrocracked heavy naphtha, hydrotreated coker gasoline, ethylene cracking gasoline raffinate, catalytic cracking gasoline, or a mixture thereof. Preferably, the naphtha contains cycloalkanes with a carbon number of 6-12, paraffins with a carbon number of 6-12, and aromatics with a carbon number of 6-12, with an initial boiling point of 80-95°C and a final boiling point of 135-180°C.

[0032] In this application, unless otherwise indicated, all pressures given are absolute pressures.

[0033] In this application, except for the contents explicitly stated, any matters or issues not mentioned are directly applicable to those known in the art without any changes. Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or technical ideas formed thereby are deemed to be part of the original disclosure or original record of this application, and should not be regarded as new content not disclosed or anticipated herein, unless a person skilled in the art considers that the combination is obviously unreasonable.

[0034] All patent and non-patent literature, including but not limited to textbooks and journal articles, mentioned herein are incorporated by reference in their entirety.

[0035] Traditionally, it is believed that L molecular sieves have small pores and aromatic hydrocarbons above C8 cannot be generated or converted in their pores. Therefore, L molecular sieves are mainly used as catalysts for the selective dehydrogenation and cyclization of C6-C7 paraffins. However, the inventors of this application unexpectedly discovered that C9 + Aromatic hydrocarbons can be efficiently dealkylated from side chains in the presence of hydrogen and a KL zeolite-based catalyst containing platinum and specific modified metals to be converted into light aromatic hydrocarbons such as BTX, thereby obtaining the present invention.

[0036] As described above, in the first aspect, the present application provides a C9 + A method for producing light aromatic hydrocarbons from aromatic hydrocarbons, comprising: reacting C9 + Aromatic hydrocarbons are contacted with a dealkylation catalyst to undergo a dealkylation reaction to obtain light aromatic hydrocarbons. The dealkylation catalyst comprises KL zeolite and platinum and a modifying metal supported thereon, wherein the modifying metal is selected from Group IIA metals and rare earth metals.

[0037] In a preferred embodiment, the dealkylation catalyst comprises KL zeolite and, based on the KL zeolite, 0.1-1.5% by mass, preferably 0.3-1.2% by mass, of platinum, and 0.02-4.0% by mass, preferably 0.1-3.0% by mass, of the modifying metal, wherein the amounts of platinum and modifying metal are calculated as metals. Further preferably, the Group IIA metal is selected from barium and calcium, and the rare earth metal is selected from one or more of La, Ce, Gd, Y, Sm, and Yb. Particularly preferably, the average crystallite diameter of the KL zeolite is 0.1-2 μm.

[0038] The dealkylation catalyst can be prepared by conventional methods in the art. In a preferred embodiment, the dealkylation catalyst can be prepared by a method comprising the following steps: impregnating KL zeolite with an aqueous solution containing a platinum compound and a compound containing a Group IIA metal and / or a rare earth metal, followed by drying and calcining. The platinum compound is preferably a compound containing a Pt cation, such as Pt(NH3)2C12; the compound containing a Group IIA metal and a rare earth metal is preferably a soluble hydroxide, chloride or nitrate of the corresponding metal, such as BaCl2. The drying temperature is preferably 90-150°C, and the time is preferably 8-24 hours. The calcination temperature is preferably 300-400°C, and the time is preferably 2-8 hours.

[0039] In a preferred embodiment, the dealkylation reaction conditions include: a temperature of 350-490°C, preferably 450-480°C, a pressure of 0.1-4.0 MPa, preferably 0.1-2.0 MPa, more preferably 0.1-0.5 MPa, C9 + Aromatic mass space velocity is 1-20h -1 , preferably 1-10h -1 , hydrogen / C9 + The molar ratio of aromatic hydrocarbons is 0.5-20:1, preferably 1-10:1.

[0040] In a further preferred embodiment, the dealkylation reaction can be carried out in one reactor or multiple (e.g., 2-3) reactors connected in series, preferably one reactor or two reactors connected in series, wherein the C9 + The mass space velocity of aromatics is 1-20h -1 , preferably 1-10h -1 , more preferably 1-5h -1 , hydrogen / C9 + The aromatic hydrocarbon molar ratio is 0.5-20:1, preferably 1-10:1, wherein when multiple reactors are used, the mass space velocity is calculated relative to the total amount of catalyst in all reactors, and the hydrogen / C9 + The aromatic hydrocarbon molar ratio is the hydrogen / hydrocarbon molar ratio at the inlet of the first reactor.

[0041] The method according to the first aspect of the present invention is applicable to various C9 + Aromatic raw materials produce light aromatics, such as C9 + The aromatic hydrocarbon content may be 20% by mass or more, 50% by mass or more, 80% by mass or more, or 90% by mass or more.

[0042] In a second aspect, the present application provides a method comprising: + A method for producing light aromatic hydrocarbons from paraffin raw materials comprises the following steps:

[0043] 1) Include C9 + The paraffinic hydrocarbon raw material is contacted with a dehydrogenation catalyst in the presence of hydrogen in the first reaction zone to react at least part of the C9 + Alkanes undergo dehydrogenation and cyclization to produce C9 + Aromatic hydrocarbons, optionally separating the obtained product to obtain C9 + A stream of aromatic hydrocarbons, wherein the dehydrogenation catalyst comprises alumina and a Group VIII metal, a Group IVA metal, a Group IA metal and a halogen supported thereon;

[0044] 2) Make the product obtained in step 1) contain C9 + The aromatic hydrocarbon stream is contacted with a dealkylation catalyst in the presence of hydrogen in a second reaction zone to dealkylate at least a portion of the C9 + Aromatic hydrocarbons undergo a dealkylation reaction to obtain light aromatic hydrocarbons, wherein the dealkylation catalyst comprises KL zeolite and platinum and a modifying metal supported thereon, wherein the modifying metal is selected from Group IIA metals and rare earth metals.

[0045] In a preferred embodiment, the reaction conditions of step 1) include: a temperature of 400-500°C, preferably 450-480°C, a pressure of 0.1-4.0 MPa, preferably 0.1-2.0 MPa, more preferably 0.1-0.5 MPa, and the C9 + The mass space velocity of the paraffin raw material is 1-50h -1 , preferably 1-20h -1 , more preferably 1-10h -1 , the hydrogen / hydrocarbon molar ratio is 0.5-20:1, preferably 1-10:1.

[0046] In certain preferred embodiments, the first reaction zone comprises one reactor or multiple reactors (e.g., 2-5 reactors connected in series), preferably one reactor or 2-4 reactors connected in series, wherein the first reaction zone comprises C9 + The mass space velocity of the paraffin raw material can be 1-50h -1 , preferably 1-20h -1 , more preferably 1-10h-1 , the hydrogen / hydrocarbon molar ratio is 0.5-20:1, preferably 1-10:1, wherein when multiple reactors are used, the mass space velocity is calculated relative to the total amount of catalyst in all reactors in the first reaction zone, and the hydrogen / hydrocarbon molar ratio is the hydrogen / hydrocarbon molar ratio at the inlet of the first reactor.

[0047] According to this application, step 1) can make the C9 + Alkanes undergo dehydrogenation and cyclization to produce C9 + Aromatic hydrocarbons. At the same time, if C6-C8 cycloalkanes are also present in the raw materials, step 1) can also cause the cycloalkanes to undergo a dehydrogenation reaction to be directed into light aromatic hydrocarbons of the same carbon number. Preferably, in the dehydrogenation catalyst used in step 1), the Group VIII metal is selected from platinum, palladium and iridium, the Group IVA metal is selected from tin, germanium and silicon, the Group IA metal is selected from potassium, sodium, rubidium and cesium, and the halogen is selected from chlorine, fluorine, bromine and iodine. To control the reaction in step 1), it is preferred to use a catalyst with low acidity to suppress the C7 - Dehydrocyclization and hydrocracking of light alkanes. In a preferred embodiment, the dehydrogenation catalyst comprises an alumina support and, based on the support, 0.1-2.0 mass% of a Group VIII metal, preferably platinum, 0.1-2.0 mass% of a Group IVA metal, preferably tin, 0.01-0.2 mass% of a Group IA metal, preferably potassium, and 0.3-5 mass% of a halogen, preferably chlorine, wherein the contents of the metals and halogens are calculated as elements.

[0048] In a further preferred embodiment, based on the alumina support, the dehydrogenation catalyst has a platinum content of 0.1-1.0 mass %, a tin content of 0.1-1.0 mass %, a potassium content of 0.02-0.1 mass %, and a chlorine content of 0.5-1.5 mass %.

[0049] In a preferred embodiment, the specific surface area of ​​the alumina support is 120-220 m 2 / g, more preferably 140-190m 2 The alumina carrier may be in various shapes, such as strips and spheres, preferably spheres, with a diameter of 1.5-2.0 mm. The alumina is preferably γ-alumina.

[0050] The dehydrogenation catalyst can be prepared using conventional methods in the art. In a preferred embodiment, the dehydrogenation catalyst can be prepared by impregnating an alumina support containing a Group IVA metal (such as tin) with an aqueous solution of a platinum-containing compound and a Group IA metal halide (such as chloride). After impregnation, the solid is dried, activated with water and chlorine, and reduced to obtain the target catalyst. Preferably, the platinum-containing compound is chloroplatinic acid.

[0051] In a further preferred embodiment, the impregnation temperature in the catalyst preparation method is 10-50°C, the drying temperature is 90-150°C, and the drying time is preferably 8-24 hours. The water-chlorine activation is performed by treating the dried solid in air containing water and HCl. The water-chlorine activation temperature is preferably 460-540°C, the time is preferably 2-12 hours, and the water / HCl molar ratio is preferably 10-100:1. The reducing gas used in the reduction is preferably hydrogen, the reduction temperature is preferably 480-520°C, and the time is preferably 2-12 hours.

[0052] According to the present application, step 2) can make the C9 + Aromatic hydrocarbons are converted into light aromatic hydrocarbons by removing side chain alkyls. Meanwhile, if C6-C8 paraffins exist in the reaction product of step 1), step 2) can also cause the C6-C8 paraffins to undergo a dehydrogenation cyclization reaction to be converted into light aromatic hydrocarbons with the same carbon number.

[0053] In a preferred embodiment, the reaction conditions of step 2) include: a temperature of 350-490°C, preferably 450-480°C, a pressure of 0.1-4.0 MPa, preferably 0.1-2.0 MPa, more preferably 0.1-0.5 MPa, and the + The mass space velocity of the aromatics flow is 1-20h -1 , preferably 1-10h -1 , the hydrogen / hydrocarbon molar ratio is 0.5-20:1, preferably 1-10:1.

[0054] In a further preferred embodiment, the second reaction zone comprises one reactor or multiple (e.g., 2-3) reactors connected in series, preferably one reactor or two reactors connected in series, and the C9 + The mass space velocity of the aromatics flow can be 1-20h -1 , preferably 1-10h -1 , more preferably 1-5h -1 , the hydrogen / hydrocarbon molar ratio is 0.5-20:1, preferably 1-10:1, wherein when multiple reactors are used, the mass space velocity is calculated relative to the total amount of catalyst in all reactors in the second reaction zone, and the hydrogen / hydrocarbon molar ratio is the hydrogen / hydrocarbon molar ratio at the inlet of the first reactor.

[0055] In a preferred embodiment, the various features of the dealkylation catalyst used in step 2) are as described above in the first aspect and will not be repeated here.

[0056] In a preferred embodiment, the mass ratio of the dehydrogenation catalyst used in step 1) to the dealkylation catalyst used in step 2) is 1:(0.25-5), preferably 1:(1.2-3).

[0057] In the method of the present application, the conversion of hydrocarbons to aromatics in steps 1) and 2) is an endothermic reaction. To maintain the required reaction temperature, an intermediate heating furnace is preferably provided between the first and second reaction zones, and between the series of reactors provided within the respective reaction zones. The reactors suitable for steps 1) and 2) of the method of the present application can be either fixed-bed reactors or moving-bed reactors, with fixed-bed reactors being preferred.

[0058] In certain preferred embodiments of the method of the present application, the step 1) comprises C9 + The raw material of paraffin is naphtha, for example, it can be selected from straight-run naphtha, hydrocracking heavy naphtha, hydrogenated coker gasoline, ethylene cracking gasoline raffinate, catalytic cracking gasoline, or any mixture thereof. In a further preferred embodiment, the naphtha contains cycloalkanes with a carbon number of 6-12, paraffins with a carbon number of 6-12, and aromatics with a carbon number of 6-12, with an initial boiling point of 80-95°C and a final boiling point of 135-180°C. Due to the limitations of the distillation separation accuracy, the naphtha may also contain a small amount of C5 hydrocarbons, the proportion of which is generally no more than 0.5% by mass. In order to make the final boiling point of the reaction product meet the requirements of gasoline blending, the naphtha has a carbon number higher than C 11 Hydrocarbons (C 11 + ) is usually not more than 1 mass %.

[0059] In such a preferred embodiment, naphtha is introduced into the first reaction zone, and in step 1), the reaction conditions are controlled to perform a moderate dehydrogenation reaction, so that the cycloalkanes therein undergo a dehydrogenation reaction to generate aromatic hydrocarbons with the same carbon number, C9 + Alkanes undergo dehydrogenation and cyclization reactions and are also converted into aromatic hydrocarbons with the same carbon number, while minimizing the amount of C7 - The paraffin undergoes dehydrogenation cyclization or cracking reaction; then, the reaction product of the first reaction zone is directly introduced into the second reaction zone without separation, and in step 2) the C9 + Aromatic hydrocarbons are converted into light aromatic hydrocarbons, such as BTX, by removing side chain alkyls. At the same time, unreacted C6-C8 paraffins undergo dehydrogenation and cyclization to generate aromatic hydrocarbons of corresponding carbon numbers. The method of this preferred embodiment can convert more paraffins in naphtha into aromatic hydrocarbons through directional reaction, and make C9 + Aromatic hydrocarbons undergo dealkylation to generate light aromatic hydrocarbons, such as BTX, thereby increasing the yield of light aromatic hydrocarbons.

[0060] In such a preferred embodiment, step 1) mainly carries out a dehydrogenation conversion reaction of naphtha, during which the easily reactive cycloalkanes in the naphtha are dehydrogenated to generate aromatics, and the conversion of paraffins is controlled to make the more reactive C9+ Alkanes undergo dehydrogenation cyclization reaction, C7 - Paraffins are not converted as much as possible. In the dehydrogenation reaction process of step 1), the C7 - The conversion of paraffins can also control the cracking reaction of light hydrocarbons, thereby maintaining the content of C6-C8 paraffins and increasing the content of light aromatics in the final reaction product.

[0061] In certain further preferred embodiments, the naphtha is first subjected to a hydrotreating treatment before entering the first reaction zone to remove impurities such as arsenic, lead, copper, sulfur, and nitrogen. After the hydrotreating treatment, the naphtha generally does not contain olefins.

[0062] In certain further preferred embodiments, in step 1), the conversion rate of cycloalkanes in naphtha is controlled to be not less than 90% by mass, C9 + The conversion rate of paraffins is 70-95% by mass. Preferably, the control can be achieved by selecting appropriate reaction conditions, such as adjusting the reaction temperature or the mass space velocity of the naphtha feed, or by changing the content of the Group IA metal, such as potassium, in the dehydrogenation catalyst to adjust the reaction selectivity of the dehydrogenation catalyst.

[0063] In a further preferred embodiment, in step 1), the conversion rate of cycloalkanes in the naphtha is controlled to be no less than 90% by mass, wherein the conversion rates of both C7 and C8 cycloalkanes are no less than 95% by mass, and the conversion rate of C6 cycloalkanes is no less than 70% by mass. Preferably, such control can be achieved by selecting a suitable reaction temperature or a suitable naphtha feed space velocity.

[0064] In a further preferred embodiment, in step 1), the conversion rate of paraffins in naphtha is controlled to be no more than 60% by mass, wherein the conversion rate of C6 paraffins is no more than 18% by mass, the conversion rate of C7 paraffins is no more than 30% by mass, the conversion rate of C8 paraffins is no more than 70% by mass, and the conversion rate of C9 paraffins is no more than 10% by mass. + The conversion rate of paraffins is 70-95% by mass. Preferably, the control can be achieved by changing the content of Group IA metals, such as potassium, in the dehydrogenation catalyst to adjust the selectivity of the dehydrogenation cyclization reaction.

[0065] The preferred embodiments of the present application will be further described below with reference to the accompanying drawings.

[0066] FIG1 is a flow diagram of a preferred embodiment of the method of the present application. As shown in FIG1, the pre-hydrogenated naphtha is mixed with hydrogen pressurized by the circulating hydrogen compressor and entering through pipeline 102 via pipeline 101, then enters the feed heat exchanger 103, exchanges heat with the reaction product of the second reaction zone from pipeline 112, and then enters the feed heating furnace 105 via pipeline 104; after being heated, it enters the first reaction zone 107 via pipeline 106, where the cycloalkanes in the naphtha are dehydrogenated to aromatic hydrocarbons under the action of the dehydrogenation catalyst, and C9 + Dehydrogenation and cyclization of paraffins to produce C9 + Aromatic hydrocarbons. The reaction product flowing out of the first reaction zone 107 enters the intermediate heating furnace 109 through pipeline 108, and after being heated, enters the second reaction zone 111 through pipeline 100. Under the action of the dealkylation catalyst, C9 + Aromatic hydrocarbons are dealkylated to produce light aromatics (such as BTX), while C6-C8 paraffins undergo a dehydrogenation cyclization reaction to produce light aromatics. The reaction product from the second reaction zone enters feed heat exchanger 103 via pipeline 112, where it exchanges heat with naphtha and cools before entering gas-liquid separator 114 via pipeline 113 for gas-liquid separation. The separated liquid phase is discharged via pipeline 117, where it undergoes product recontact and separation to produce light aromatics products. The separated gas phase is divided into two parts. One part is fed to the inlet of the recycle hydrogen compressor via pipeline 115, where it is pressurized and then mixed with the naphtha feedstock in pipeline 101 via pipeline 102. The other part is discharged via pipeline 116, where it is pressurized by a booster and then enters a recontact tank (not shown). It is then mixed and cooled with the liquid phase from pipeline 117 for re-equilibrium flash separation. Most of the hydrocarbons in the gas phase are condensed into the liquid phase, and then the gas phase is discharged as hydrogen product.

[0067] To simplify the process notation, other equipment used in the above preferred embodiment of the method of the present application, such as a naphtha feed pump, a reaction product air cooler, a gas-liquid separator bottom pump, etc., are not shown in FIG1 .

[0068] In certain preferred embodiments, the present application provides the following technical solutions:

[0069] 1. A method for producing light aromatics from naphtha, comprising the following steps:

[0070] (1) Naphtha is passed into the first reaction zone and brought into contact with a dehydrogenation catalyst to carry out a dehydrogenation conversion reaction, so that the conversion rate of cycloalkanes in the naphtha is not less than 90% by mass, C9 + The conversion rate of paraffin is 70-95% by mass.

[0071] (2) The reaction product of the first reaction zone is passed into the second reaction zone and contacted with the dealkylation catalyst to make the C9 +Aromatic hydrocarbons undergo dealkylation, and C6-C8 paraffins are dehydrogenated and cyclized to convert into light aromatic hydrocarbons.

[0072] 2. The method according to item 1, characterized in that in step (1), the conversion rate of the dehydrogenation reaction of cycloalkanes in naphtha is not less than 90% by mass, wherein the conversion rate of the dehydrogenation reaction of both C7 and C8 cycloalkanes is not less than 95% by mass, and the conversion rate of the dehydrogenation reaction of C6 cycloalkanes is not less than 70% by mass.

[0073] 3. The method according to item 1 is characterized in that in step (1), the conversion rate of the dehydrogenation cyclization reaction of the paraffin is not more than 60% by mass, wherein the conversion rate of C6 paraffin is not more than 18% by mass, the conversion rate of C7 paraffin is not more than 30% by mass, and the conversion rate of C8 paraffin is not more than 70% by mass.

[0074] 4. The method according to item 1, characterized in that the dehydrogenation catalyst described in step (1) comprises an alumina carrier and a content of 0.1-2.0 mass% of platinum, 0.1-2.0 mass% of tin, 0.01-0.2 mass% of Group IA metal and 0.3-5 mass% of chlorine, based on the carrier.

[0075] 5. The method according to item 4, characterized in that the aluminum oxide is γ-aluminum oxide and the Group IA metal is potassium.

[0076] 6. The method according to item 1 is characterized in that the temperature of the dehydrogenation conversion reaction in step (1) is 400-500°C and the pressure is 0.1-4.0 MPa.

[0077] 7. The method according to item 1 or 6, characterized in that the dehydrogenation reaction zone in step (1) comprises 1-5 reactors connected in series, and the mass space velocity of naphtha entering the dehydrogenation reaction zone is 1-50h -1 The hydrogen / hydrocarbon molar ratio in the dehydrogenation conversion reaction zone is 0.5-20:1.

[0078] 8. The method according to item 1, characterized in that the dealkylation catalyst in step (2) comprises KL zeolite and 0.1-1.5 mass % of platinum and 0.02-4.0 mass % of Group IIA metal supported thereon, calculated based on the KL zeolite.

[0079] 9. The method according to item 8, characterized in that the Group IIA metal is barium or calcium.

[0080] 10. The method according to item 1 is characterized in that the temperature of the second reaction zone in step (2) is 350-490°C and the pressure is 0.1-4.0 MPa.

[0081] 11. The method according to item 1 or 10, characterized in that the second reaction zone in step (2) comprises 1-3 reactors connected in series, and the mass space velocity of the reaction product of the first reaction zone entering the second reaction zone is 1-20h -1 , the hydrogen / hydrocarbon molar ratio in the second reaction zone is 0.5-20:1.

[0082] 12. The method according to item 1 is characterized in that the mass ratio of the dehydrogenation catalyst to the dealkylation catalyst is 1:(0.25-5).

[0083] Example

[0084] The present application will be further described below by way of examples, but the present application is not limited thereto.

[0085] Catalyst Preparation Example

[0086] Example I-1

[0087] This example illustrates the preparation of the dehydrogenation catalyst used in this application.

[0088] (1) Preparation of tin-containing γ-Al2O3 pellets with uniform tin distribution

[0089] 100 g of aluminum hydroxide powder (produced by Sasol Germany, brand SB, with an aluminum oxide content of 72% by mass) and an appropriate amount of deionized water were stirred and slurried to obtain a slurry with a liquid / solid mass ratio of 2.0. 7.5 ml of dilute nitric acid, 30 g of urea, and a predetermined amount of SnCl2 hydrochloric acid solution in a volume ratio of 1:1 were added to the slurry so that the Sn content in the solution was 0.30% by mass relative to the dry basis aluminum oxide. The mixture was stirred for 1 hour, 30 g of kerosene and 3 g of fatty alcohol polyoxyethylene ether were added and stirred for 1 hour, and then drop-casted into a ball-shaped oil-ammonia column. The wet ball was solidified in ammonia water for 1 hour, then filtered, rinsed with deionized water 2-3 times, dried at 60°C for 6 hours, dried at 120°C for 10 hours, and calcined in air at 680°C for 4 hours. The water content in the calcination atmosphere was 15% by volume. A Sn-containing γ-Al2O3 spherical carrier was obtained with an average diameter of 1.62 mm and a specific surface area of ​​165 m2 as determined by the BET method. 2 / g.

[0090] (2) Preparation of target catalyst

[0091] A solution was prepared by combining 0.5882 g of chloroplatinic acid, 0.1526 g of potassium chloride, 5.40 g of 37% by mass hydrochloric acid, and 175 g of deionized water, wherein the HCl content was 2.0% by mass relative to the dry basis of the alumina support. The prepared solution was used as an impregnation liquid to impregnate the Sn-containing γ-Al2O3 spherical support prepared in step (1) at 25°C for 4 hours, with a liquid / solid ratio of 1.8 mL / g. After impregnation, the impregnation system was evaporated to dryness using a rotary evaporator. The resulting solid was dried at 120°C for 12 hours, activated with water chlorine at 510°C for 4 hours, with the molar ratio of water to HCl in the air used for the activation being 40:1, and then reduced with hydrogen at 500°C for 4 hours to obtain dehydrogenation catalyst A.

[0092] The component contents of catalyst A calculated based on the alumina carrier are: 0.27 mass % Pt, 0.30 mass % Sn, 0.08 mass % K, and 1.0 mass % Cl. The contents of each element are determined by X-ray fluorescence analysis.

[0093] Example I-2

[0094] This example illustrates the preparation of the Pt-Ba / KL dealkylation catalyst used in this application.

[0095] (1) Preparation of directing agent for synthesizing KL zeolite

[0096] 12.08 g of Al(OH)3 (produced by Aluminum Corporation of China, brand H-WF-10, the same below) was added to 264.12 ml of a solution containing 77.57 g of KOH (purity 85.7% by mass, the same below) and heated to dissolve to obtain an aluminum sol. The aluminum sol was then added with stirring to 435.6 g of silica sol (containing 30% by mass SiO2, pH 9, the same below) preheated to 50°C, and stirred 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 served as a target-directing agent. The molar ratio of the components was K2O:Al2O3:SiO2:H2O = 7.9:1:29:430.

[0097] (2) Preparation of KL zeolite carrier

[0098] 107 g of Al(OH)3 was added to 1100 mL of a solution containing 210 g of KOH and heated to dissolve to obtain an aluminum sol. The obtained aluminum sol was added together with the directing agent prepared in step (1) to a reaction kettle containing 1200 mL of silica sol under stirring, wherein the molar ratio of Al2O3 contained in the added directing agent to the Al2O3 contained in the material without the directing agent was 5:95. The mixture was stirred for 0.5 hour to form a white reaction mixture gel, wherein the molar ratio of the components was K2O:Al2O3:SiO2:H2O=2.68:1:10:178.

[0099] The white gel was heated to 150°C with stirring, then stopped for static crystallization for 72 hours. The crystallized product was rapidly cooled to 40°C and centrifuged to remove the upper liquid. The solid was then washed with deionized water until the liquid pH was 9-10. The resulting solid was dried at 120°C for 10 hours to obtain KL zeolite, in which the molar ratio of the components was K2O:Al2O3:SiO2 = 1.2:1:5.6, and the average crystallite diameter was 0.3-1.2 μm.

[0100] (3) Preparation of Pt-Ba / KL catalyst

[0101] 1.54 g of Pt(NH₃)₂Cl₂ and 1.52 g of BaCl₂ were dissolved in 150 g of deionized water and stirred thoroughly to obtain an impregnation solution. The impregnation solution was added to 100 g of the KL zeolite support prepared in step (2). After impregnation for 6 h, the mixture was rotary evaporated to dryness. The resulting solid was dried at 120°C for 12 h and calcined in air at 350°C for 4 h to produce Pt-Ba / KL zeolite, designated as Catalyst B. The Pt content of Catalyst B, based on the KL zeolite, was 1.0 mass % and the Ba content was 1.0 mass %.

[0102] Example I-3

[0103] This example illustrates the preparation of the Pt-Ca / KL dealkylation catalyst used in this application.

[0104] 1.54 g of Pt(NH₃)₂Cl₂ and 2.78 g of CaCl₂ were dissolved in 150 g of deionized water and stirred thoroughly to obtain an impregnation solution. This impregnation solution was added to 100 g of the KL zeolite support prepared in Example I-2. After impregnation for 6 hours, the solution was rotary evaporated to dryness. The resulting solid was dried at 120°C for 12 hours and calcined in air at 350°C for 4 hours to produce Pt-Ca / KL zeolite, designated as Catalyst B1. The Pt content of Catalyst B1, based on the KL zeolite, was 1.0 mass% and the Ca content was 1.0 mass%.

[0105] Example I-4

[0106] This example illustrates the preparation of the Pt-La / KL dealkylation catalyst used in this application.

[0107] 1.54 g of Pt(NH₃)₂Cl₂ and 1.77 g of LaCl₃ were dissolved in 150 g of deionized water and stirred thoroughly to obtain an impregnation solution. This impregnation solution was added to 100 g of the KL zeolite support prepared in Example I-2. After impregnation for 6 hours, the solution was rotary evaporated to dryness. The resulting solid was dried at 120°C for 12 hours and calcined in air at 350°C for 4 hours to produce Pt-La / KL zeolite, designated as Catalyst B2. The Pt content of Catalyst B2, based on the KL zeolite, was 1.0 mass% and the La content was 1.0 mass%.

[0108] Example I-5

[0109] This example illustrates the preparation of the Pt-Ce / KL dealkylation catalyst used in this application.

[0110] 1.54 g of Pt(NH₃)₂Cl₂ and 1.76 g of CeCl₃ were dissolved in 150 g of deionized water and stirred thoroughly to obtain an impregnation solution. This impregnation solution was added to 100 g of the KL zeolite support prepared in Example I-2. After impregnation for 6 hours, the solution was rotary evaporated to dryness. The resulting solid was dried at 120°C for 12 hours and calcined in air at 350°C for 4 hours to produce Pt-Ce / KL zeolite, designated Catalyst B3. The Pt content of Catalyst B3, based on the KL zeolite, was 1.0 mass% and the Ce content was 1.0 mass%.

[0111] Example I-6

[0112] This example illustrates the preparation of the Pt-Yb / KL dealkylation catalyst used in this application.

[0113] 1.54 g of Pt(NH₃)₂Cl₂ and 1.62 g of YbCl₃ were dissolved in 150 g of deionized water and stirred thoroughly to obtain an impregnation solution. This impregnation solution was added to 100 g of the KL zeolite support prepared in Example I-2. After impregnation for 6 hours, the solution was rotary evaporated to dryness. The resulting solid was dried at 120°C for 12 hours and calcined in air at 350°C for 4 hours to produce Pt-Yb / KL zeolite, designated as Catalyst B4. The Pt content of Catalyst B4, based on the KL zeolite, was 1.0 mass% and the Yb content was 1.0 mass%.

[0114] Example I-7

[0115] This example illustrates the preparation of another Pt-Ba / KL dealkylation catalyst used in this application.

[0116] 1.26 g of Pt(NH₃)₂Cl₂ and 1.52 g of BaCl₂ were dissolved in 150 g of deionized water and stirred thoroughly to obtain an impregnation solution. This impregnation solution was added to 100 g of the KL zeolite support prepared in Example I-2. After impregnation for 6 hours, the solution was rotary evaporated to dryness. The resulting solid was dried at 120°C for 12 hours and calcined in air at 350°C for 4 hours to produce Pt-Ba / KL zeolite, designated Catalyst B5. The Pt content of Catalyst B5, based on the KL zeolite, was 0.82 mass% and the Ba content was 1.0 mass%.

[0117] Example I-8

[0118] This example illustrates the preparation of another Pt-Ba / KL dealkylation catalyst used in this application.

[0119] 0.62 g of Pt(NH₃)₂Cl₂ and 0.30 g of BaCl₂ were dissolved in 150 g of deionized water and stirred thoroughly to obtain an impregnation solution. This impregnation solution was added to 100 g of the KL zeolite support prepared in Example I-2. After impregnation for 6 hours, the solution was rotary evaporated to dryness. The resulting solid was dried at 120°C for 12 hours and calcined in air at 350°C for 4 hours to produce Pt-Ba / KL zeolite, designated Catalyst B6. The Pt content of Catalyst B6, based on the KL zeolite, was 0.4% by mass and the Ba content was 0.2% by mass.

[0120] Comparative Example I-1

[0121] This comparative example illustrates the preparation of a Pt / KL zeolite catalyst not used in this application.

[0122] 90 g of the KL zeolite powder synthesized in step (2) of Example I-2 was uniformly mixed with 10 g of amorphous silica powder, and an appropriate amount of sodium hydroxide aqueous solution was added and kneaded to a moisture content of 40% by mass. The mixture was then extruded on an extruder and calcined at 400°C to obtain a shaped KL zeolite carrier.

[0123] 1.14 g of Pt(NH₃)₂Cl₂ was dissolved in 150 g of deionized water and stirred thoroughly to obtain an impregnation solution. This impregnation solution was added to the molded KL zeolite support and impregnated for 6 hours before rotary evaporation to dryness. The resulting solid was dried at 120°C for 12 hours and calcined in air at 350°C for 4 hours to produce Pt / KL zeolite, designated Catalyst R. The Pt content of Catalyst R, based on the KL zeolite, was 0.82% by mass.

[0124] Comparative Example I-2

[0125] This comparative example illustrates the preparation of a Pt / KL zeolite catalyst not used in this application.

[0126] A Pt / KL zeolite catalyst was prepared according to Example 1-2, except that the impregnation solution used in step (3) did not contain BaCl2. The resulting Pt / KL zeolite was designated as Catalyst R1. The Pt content of Catalyst R1, based on the KL zeolite, was 1.0% by mass.

[0127] Comparative Example I-3

[0128] This comparative example illustrates the preparation of a Pt / KL zeolite catalyst not used in this application.

[0129] A Pt / KL zeolite catalyst was prepared as in Example 1-8, except that the impregnation solution used did not contain BaCl2. The resulting Pt / KL zeolite was designated as Catalyst R2. The Pt content of Catalyst R2, based on the KL zeolite, was 0.4% by mass.

[0130] Application Examples

[0131] Example II-1

[0132] This example illustrates the application of the method according to the first aspect of the application.

[0133] 30 g of catalyst B prepared in Example I-2 was loaded into a fixed bed reactor and C9 + Aromatic hydrocarbons are used as raw materials for dealkylation reaction. + Aromatic hydrocarbons were obtained by distillation of conventional reforming products. Their properties and compositions are shown in Table II-1 and Table II-2. The reaction temperature, pressure, mass space velocity, and hydrogen / hydrocarbon molar ratio used in this example, as well as the reaction results, are shown in Table II-3.

[0134] Table II-1 C9 used in the examples + Properties of aromatic hydrocarbons

[0135] Project Initial distillation point 10 volume % 50 volume % 90 volume % Final distillation point Distillation temperature, ℃ 149.8161.9167.5179.9202.3

[0136] Table II-2 C9 used in the examples + Composition of aromatic hydrocarbons

[0137] Hydrocarbon carbon number Alkanes, mass% Cycloalkanes, mass% Aromatics, mass% C70.020.010.06C80.010.010.58C90.000.0076.09C 10 0.000.0021.46C 11 + 0.000.001.76Total 0.030.0299.95

[0138] Example II-2

[0139] The experiment was carried out with reference to Example II-1, except that the reactor was loaded with catalyst B1 prepared in Example I-3. The reaction conditions and results are shown in Table II-3.

[0140] Example II-3

[0141] The experiment was carried out with reference to Example II-1, except that the reactor was loaded with catalyst B2 prepared in Example I-4. The reaction conditions and results are shown in Table II-3.

[0142] Example II-4

[0143] The experiment was carried out with reference to Example II-1, except that the reactor was loaded with catalyst B6 prepared in Example I-8. The reaction conditions and results are shown in Table II-3.

[0144] Comparative Example II-1

[0145] This comparative example illustrates the results using a KL zeolite catalyst other than that used in this application.

[0146] The experiment was carried out with reference to Example II-1, except that the reactor was loaded with catalyst R1 prepared in Comparative Example I-2. The reaction conditions and results are shown in Table II-3.

[0147] Comparative Example II-2

[0148] This comparative example illustrates the results using a KL zeolite catalyst other than that used in this application.

[0149] The experiment was carried out with reference to Example II-1, except that the reactor was loaded with catalyst R2 prepared in Comparative Example I-3. The reaction conditions and results are shown in Table II-3.

[0150] Table II-3 Reaction conditions and results of Examples II-1 to II-4 and Comparative Examples II-1 to II-2

[0151]

[0152] From the results in Table II-3, we can see that when the Pt content is the same, the C9 + Aromatic hydrocarbons were used as raw materials for dealkylation reaction by the method of the present application. Compared with the comparative example II-1, the examples II-1 to II-3 using catalysts B, B1 and B2 all showed higher raw material conversion rate, light aromatic hydrocarbon yield and selectivity, achieving C9 + The purpose is to convert as much aromatic hydrocarbons as possible into light aromatic hydrocarbons; and Example II-4 using catalyst B6 also shows improved raw material conversion rate, light aromatic hydrocarbon yield and selectivity compared with Comparative Example II-2.

[0153] Examples III-1 to III-3

[0154] This example illustrates the application of step 1) of the method according to the second aspect of the present application.

[0155] 15 g of Catalyst A prepared in Example I-1 was loaded into a small fixed-bed reactor and subjected to naphtha dehydrogenation reactions under various reaction conditions. The properties and composition of the naphtha used are shown in Tables III-1 and III-2. The reaction conditions and results for each example are shown in Table III-3.

[0156] Table III-1 Properties of naphtha used in the examples

[0157] Project Initial distillation point 10 volume % 50 volume % 90 volume % Final distillation point Distillation temperature, ℃ 84106121153170

[0158] Table III-2 Composition of naphtha used in the examples

[0159] Hydrocarbon carbon number Alkanes, mass% Cycloalkanes, mass% Aromatics, mass% C50.150.03-C63.433.170.38C79.3410.462.76C815.9213.956.51C910.8311.372.92C 10 6.401.840.16C 11 + 0.3800Total46.4540.8212.73

[0160] Comparative Example III-1

[0161] This comparative example illustrates the results of existing continuous reforming technology.

[0162] A small fixed-bed reactor was loaded with 15 g of reforming catalyst C (manufactured by Hunan Jianchang Petrochemical Co., Ltd., brand RC011). Naphtha having the properties and composition described in Tables III-1 and III-2 was introduced into the reactor for a catalytic reforming reaction. The support for reforming catalyst C consisted of γ-Al2O3 pellets, containing 0.28 mass% Pt, 0.31 mass% Sn, and 1.10 mass% Cl, calculated based on the support. The reaction temperature, pressure, mass space velocity, and hydrogen / hydrocarbon molar ratio used in this comparative example, as well as the reaction results, are shown in Tables III-3 and III-4.

[0163] Table III-3 Reaction conditions and results of Examples III-1 to III-3 and Comparative Example III-1

[0164] Project Example III-1 Example III-2 Example III-3 Comparative Example III-1 Reaction temperature, ℃ 460470500520 Reaction pressure, MPa 0.450.450.450.45 Mass space velocity, h -1 2.62.610.42.6Hydrogen / hydrocarbon molar ratio6:16:16:16:1C6 cycloalkane conversion, mass%74.8579.7387.1794.83C7 cycloalkane conversion, mass%96.9297.5898.6798.86C8 cycloalkane conversion, mass%96.6196.9797.6899.58C9 + Cycloalkane conversion, mass% 90.11 92.88 96.88 99.27 Total cycloalkane conversion, mass% 91.95 93.72 96.05 98.09 C6 paraffin conversion, mass% 12.47 12.80 16.99 36.47 C7 paraffin conversion, mass% 17.13 23.00 27.73 70.87 C8 paraffin conversion, mass% 43.91 53.03 67.56 94.97 C9 + Paraffin conversion, mass% 71.8679.6090.5799.38 Total paraffin conversion, mass% 42.8247.8357.5376.54 Liquid yield, mass% 91.0090.3388.6484.46 Total aromatics yield, mass% 59.9263.4566.6770.68 Light aromatics yield, mass% 38.8641.4343.1851.96C9 + Aromatic hydrocarbon yield, mass% 21.06 22.02 23.49 18.72

[0165] From the results in Table III-3, it can be seen that after the naphtha undergoes the dehydrogenation reaction in step 1) of the present method, the total conversion rate of cycloalkanes in the product is greater than 90% by mass, and C9 + The paraffin conversion rate is greater than 70% by mass and less than 95% by mass, C7 - The conversion rate of paraffins was less than 28% by mass, indicating that the cycloalkanes in the naphtha had basically undergone dehydrogenation reaction, and C9 + Paraffins undergo dehydrogenation and cyclization reactions, and are converted into aromatic hydrocarbons with the same carbon number, while avoiding C7 - Paraffins undergo dehydrogenation cyclization or cracking reactions.

[0166] Examples III-4 to III-7

[0167] This example illustrates the application of the method according to the second aspect of the application.

[0168] According to the process shown in Figure 1, the reaction is carried out using naphtha having the properties and composition described in Table III-1 and Table III-2 as the raw material.

[0169] 15 g of Catalyst A prepared in Example I-1 was loaded into fixed-bed reactor a used in the first reaction zone 107, and 30 g of Catalyst B prepared in Example I-2 was loaded into fixed-bed reactor b used in the second reaction zone 111. Naphtha was passed into fixed-bed reactor a for dehydrogenation, and the resulting product was passed into fixed-bed reactor b for reaction. The reaction conditions and results for each example are shown in Table III-4.

[0170] Example III-8

[0171] This example illustrates the results of applying the method of the first aspect of the present application to the treatment of naphtha.

[0172] A small fixed-bed reactor was charged with 30 g of catalyst B prepared in Example I-2, and naphtha having the properties and composition described in Table III-1 and Table III-2 was introduced into the reactor for reaction. The reaction conditions and results are shown in Table III-4.

[0173] Table III-4 Reaction results of Examples III-4 to III-8 and Comparative Example III-1

[0174]

[0175] From the results in Table III-4, it can be seen that compared with the existing continuous reforming technology of Comparative Example III-1, the method according to the second aspect of the present application significantly improves the yield of light aromatics by converting naphtha in the first reaction zone and the second reaction zone, which are connected in series. + The yield of aromatics is greatly reduced, achieving the goal of producing as much light aromatics as possible from naphtha, and the resulting gas still contains a large amount of hydrogen.

[0176] At the same time, compared with the existing continuous reforming technology of comparative example III-1, the yield of light aromatics in example III-8 using the method according to the first aspect of the present application is greatly improved, and C9 + The aromatics yield is significantly reduced, and the goal of producing as much light aromatics as possible from naphtha can also be achieved, and the resulting gas still contains a large amount of hydrogen. Comparing the results of Examples III-5 to III-7 with the results of Example III-8, it can be seen that setting the dehydrogenation reaction step 1) before the dealkylation reaction step 2) can further increase the light aromatics yield and reduce C9 + Aromatic hydrocarbon yield.

[0177] In addition, from the comparison of the results in Table III-3 and Table III-4, it can be seen that setting the dealkylation reaction step 2) after the dehydrogenation reaction step 1) can greatly increase the yield of light aromatics and significantly reduce the C9 + Aromatic hydrocarbon yield.

[0178] Example III-9

[0179] This example illustrates the application of the method according to the second aspect of the application.

[0180] According to the process shown in Figure 1, the reaction is carried out using naphtha having the properties and composition described in Table III-1 and Table III-2 as the raw material.

[0181] 15 g of Catalyst A prepared in Example I-1 was loaded into fixed-bed reactor a used in the first reaction zone 107, and 30 g of Catalyst B1 prepared in Example I-3 was loaded into fixed-bed reactor b used in the second reaction zone 111. Naphtha was introduced into fixed-bed reactor a and subjected to a dehydrogenation reaction according to the reaction conditions of Example III-4. The resulting product was then introduced into fixed-bed reactor b for reaction. The reaction conditions and results of this example are shown in Table III-5.

[0182] Example III-10

[0183] The experiment was carried out in accordance with Example III-9, except that the catalyst B2 prepared in Example I-4 was loaded into reactor B. The reaction conditions and results of this example are shown in Table III-5.

[0184] Example III-11

[0185] The experiment was carried out in accordance with Example III-9, except that the catalyst B3 prepared in Example I-5 was loaded into reactor b. The reaction conditions and results of this example are shown in Table III-5.

[0186] Example III-12

[0187] The experiment was carried out in accordance with Example III-9, except that the catalyst B4 prepared in Example I-6 was loaded into reactor B. The reaction conditions and results of this example are shown in Table III-5.

[0188] Example III-13

[0189] The experiment was carried out in accordance with Example III-9, except that the catalyst B5 prepared in Example I-7 was loaded into reactor b. The reaction conditions and results of this example are shown in Table III-5.

[0190] Comparative Example III-2

[0191] This comparative example illustrates the results using a KL zeolite catalyst other than that used in this application.

[0192] The experiment was carried out in accordance with Example III-9, except that the catalyst R prepared in Comparative Example I-1 was loaded into reactor b. The reaction conditions and results of this comparative example are shown in Table III-5.

[0193] Table III-5 Reaction conditions and results of Examples III-9 to III-13 and Comparative Example III-2

[0194]

[0195] Comparing the results in Table III-5 and Table III-4, it can be seen that the light aromatics yields of Examples III-9 to III-13 were significantly higher than those of the existing continuous reforming technology described in Comparative Example III-1, thus achieving the goal of producing as much light aromatics as possible from naphtha. Compared to Example III-5, Examples III-9 to III-12 replaced Ba in the dealkylation catalyst (Catalyst B) with Ca, La, Ce, and Yb (corresponding to Catalysts B1, B2, B3, and B4), and the light aromatics yields and total aromatics yields in the products were essentially equivalent. In Example III-13, the Pt content in the dealkylation catalyst was adjusted from 1.0 mass% (Catalyst B) to 0.82 mass% (Catalyst B5), resulting in a slight decrease in the light aromatics yield and total aromatics yield, but still higher than that of Comparative Example III-2, which used a KL zeolite catalyst (Catalyst R) with a Pt content of 0.82 mass% but without the addition of a modifying metal and bonded with silica.

[0196] The preferred embodiments of the present application are described in detail above. However, the present application is not limited to the specific details of the above embodiments. Within the technical concept of the present application, various simple modifications can be made to the technical solution of the present application, and these simple modifications all fall within the scope of protection of the present application.

[0197] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this application will not further describe various possible combinations.

[0198] In addition, the various implementation methods of the present application may be arbitrarily combined, and as long as they do not violate the concept of the present application, they should also be regarded as the contents disclosed in the present application.

Claims

1. A method for producing light aromatics from C 9 + aromatics, comprising subjecting C 9 + aromatics to a dealkylation reaction by contacting with a dealkylation catalyst in the presence of hydrogen to obtain light aromatics, wherein the dealkylation catalyst comprises KL zeolite and platinum and a modified metal supported thereon, and the modified metal is selected from Group IIA metals and rare earth metals.

2. The method according to claim 1, wherein the dealkylation catalyst comprises KL zeolite and 0.1-1.5% by mass, preferably 0.3-1.2% by mass, of platinum based on the KL zeolite and 0.02-4.0% by mass, preferably 0.1-3.0% by mass, of the modified metal.

3. The method according to any one of the preceding claims, wherein the dealkylation catalyst has one or more of the following characteristics: The Group IIA metal is selected from barium and calcium; The rare earth metal is selected from La, Ce, Gd, Y, Sm and Yb; and / or The average crystal grain diameter of the KL zeolite is 0.1-2 μm.

4. The method according to any one of the preceding claims, wherein the conditions of the dealkylation reaction comprise: The temperature is 350 - 490 °C, preferably 450 - 480 °C, the pressure is 0.1 - 4.0 MPa, preferably 0.1 - 2.0 MPa, more preferably 0.1 - 0.5 MPa, C 9 + The mass hourly space velocity of C aromatics is 1 - 20 h -1 , preferably 1 - 10 h -1 , the molar ratio of hydrogen to C 9 + aromatics is 0.5 - 20:1, preferably 1 - 10:

1.

5. A method for producing light aromatics from a raw material containing C 9 + alkanes, comprising the following steps: 1) React a feedstock containing C 9 + alkanes with a dehydrogenation catalyst in the presence of hydrogen in a first reaction zone to cause at least part of the C 9 + alkanes to undergo dehydrogenative cyclization to obtain C 9 + aromatics. Optionally, separate the resulting product to obtain a stream containing C 9 + aromatics, wherein the dehydrogenation catalyst comprises alumina and Group VIII metals, Group IVA metals, Group IA metals and halogens supported thereon; 2) Contact the stream containing C 9 + aromatic hydrocarbons with a dealkylation catalyst in the presence of hydrogen in a second reaction zone, so that at least a part of the C 9 + aromatic hydrocarbons undergo a dealkylation reaction to obtain light aromatic hydrocarbons, wherein the dealkylation catalyst comprises KL zeolite and platinum and a modified metal supported thereon, and the modified metal is selected from Group IIA metals and rare earth metals.

6. The method according to claim 5, wherein the dealkylation catalyst in step 2) comprises KL zeolite and 0.1-1.5% by mass, preferably 0.3-1.2% by mass, of platinum based on the KL zeolite and 0.02-4.0% by mass, preferably 0.1-3.0% by mass, of the modified metal.

7. The method according to claim 5 or 6, wherein the dealkylation catalyst has one or more of the following characteristics: The Group IIA metal is selected from barium and calcium; The rare earth metal is selected from La, Ce, Gd, Y, Sm and Yb; and / or The average crystal grain diameter of the KL zeolite is 0.1-2 μm.

8. The method according to any one of claims 5-7, wherein: In the dehydrogenation catalyst used in step 1), the Group VIII metal is selected from platinum, palladium and iridium, the Group IVA metal is selected from tin, germanium and silicon, the Group IA metal is selected from potassium, sodium, rubidium and cesium, and the halogen is selected from chlorine, fluorine, bromine and iodine; Preferably, the dehydrogenation catalyst in step 1) comprises an alumina support and 0.1-2.0% by mass, preferably 0.1-1.0% by mass, of a Group VIII metal such as platinum, 0.1-2.0% by mass, preferably 0.1-1.0% by mass, of a Group IVA metal such as tin, 0.01-0.2% by mass, preferably 0.02-0.1% by mass, of a Group IA metal such as potassium, and 0.3-5% by mass, preferably 0.5-1.5% by mass, of a halogen such as chlorine based on the alumina support.

9. The method according to claim 8, wherein the alumina support is a γ-alumina support. Preferably, based on the alumina support, the platinum content of the dehydrogenation catalyst is 0.1-1.0% by mass, the tin content is 0.1-1.0% by mass, the potassium content is 0.02-0.1% by mass, and the chlorine content is 0.5-1.5% by mass.

10. The method according to any one of claims 5-9, wherein the reaction conditions of step 1) comprise: The reaction temperature is 400 - 500 °C, preferably 450 - 480 °C, the reaction pressure is 0.1 - 4.0 MPa, preferably 0.1 - 2.0 MPa, more preferably 0.1 - 0.5 MPa, and the mass space velocity of the feedstock containing C 9 + alkanes is 1 - 50 h -1 , preferably 1 - 20 h -1 , more preferably 1 - 10 h -1 , and the hydrogen / hydrocarbon molar ratio is 0.5 - 20:1, preferably 1 - 10:

1.

11. The method according to any one of claims 5-10, wherein the reaction conditions of step 2) comprise: The temperature is 350 - 490 °C, preferably 450 - 480 °C, the pressure is 0.1 - 4.0 MPa, preferably 0.1 - 2.0 MPa, more preferably 0.1 - 0.5 MPa, and the mass hourly space velocity of the stream containing C 9 + aromatics is 1 - 20 h -1 preferably 1 - 10 h -1 , and the hydrogen / hydrocarbon molar ratio is 0.5 - 20:1, preferably 1 - 10:

1.

12. The method according to any one of claims 5-11, wherein the mass ratio of the dehydrogenation catalyst used in step 1) to the dealkylation catalyst used in step 2) is 1:(0.25-5), preferably 1:(1.2-3).

13. The method according to any one of claims 5-12, wherein the feedstock containing C 9 + alkanes is naphtha. Preferably, the naphtha is selected from straight-run naphtha, hydrocracked heavy naphtha, hydrocracked coker gasoline, raffinate of ethylene pyrolysis gasoline, catalytically cracked gasoline or a mixture thereof. More preferably, the naphtha contains naphthenes with 6-12 carbon atoms, alkanes with 6-12 carbon atoms and aromatics with 6-12 carbon atoms, has an initial boiling point of 80-95 °C and a final boiling point of 135-180 °C.

14. The method according to claim 13 further includes a step of hydrofining the naphtha before step 1) to remove arsenic, lead, copper, sulfur and nitrogen impurities contained therein.

15. The method according to claim 13 or 14, wherein the reaction in step 1) is controlled such that the conversion rate of naphthenes in the naphtha is not less than 90% by mass, and the conversion rate of C 9 + alkanes is 70-95% by mass.

16. According to the method described in any one of claims 13-15, wherein the reaction in step 1) is controlled such that the conversion rate of naphthenes in the naphtha is not less than 90% by mass, wherein the conversion rates of both C 7 and C 8 naphthenes are not less than 95% by mass, and the conversion rate of C 6 naphthenes is not less than 70% by mass.

17. According to the method according to any one of claims 13-16, wherein the reaction in step 1) is controlled such that the conversion rate of paraffins in the naphtha is not more than 60% by mass, wherein C 6 the conversion rate of paraffins is not more than 18% by mass, C 7 the conversion rate of paraffins is not more than 30% by mass, C 8 the conversion rate of paraffins is not more than 70% by mass, C 9 + the conversion rate of paraffins is 70-95% by mass.