Fused ring aromatic selective ring opening catalysts and methods of making same, methods of making light aromatics from fused ring aromatics

Abstract

The present application relates to the technical field of catalysts, and discloses a fused ring aromatic hydrocarbon selective ring-opening catalyst, a preparation method thereof, and a method for preparing light aromatic hydrocarbons from fused ring aromatic hydrocarbons. The catalyst comprises a beta zeolite, a binder, and a metal active component, the content of the binder is 15-300 parts by weight relative to 100 parts by weight of the beta zeolite, and the content of the metal active component is 0.1-160 parts by weight. The mesopore specific surface area of the catalyst is 40-500 m 2 / g, the mesopore volume accounts for 30-95% of the total pore volume, and the mesopore volume is 0.1-0.6 cm 3 / g. The catalyst has a high carbon capacity, high activity, long service life, and good stability, and is especially suitable for the selective ring-opening reaction of fused ring aromatic hydrocarbons, has excellent conversion rate and stability of the fused ring aromatic hydrocarbons, and thus makes the process of preparing light aromatic hydrocarbons from the ring-opening of the fused ring aromatic hydrocarbons smoothly completed.

Description

Technical Field

[0001] This invention relates to the technical field of catalysts, specifically to selective ring-opening catalysts for polycyclic aromatic hydrocarbons and their preparation methods, as well as methods for preparing light aromatic hydrocarbons from polycyclic aromatic hydrocarbons. Background Technology

[0002] Aromatic hydrocarbons are an important basic raw material in petrochemicals. They are a general term for hydrocarbons containing benzene ring structures. Based on the number of benzene rings in the molecule, they can be divided into monocyclic aromatic hydrocarbons (homologues of benzene) and fused-ring (polycyclic) aromatic hydrocarbons. Among them, aromatic hydrocarbons containing 6-8 carbon atoms are called light aromatic hydrocarbons.

[0003] Benzene, toluene, and xylene (BTX) are three light aromatic hydrocarbons, all of which are primary basic organic raw materials widely used in pharmaceuticals, resins, and petroleum products. Benzene's primary use is in the production of styrene, which, through polymerization, yields polystyrene. Secondly, benzene is hydrogenated to produce cyclohexane, used in the production of nylon. Xylene has three isomers: o-xylene (OX), p-xylene (PX), and m-xylene (MX), with PX having the largest market demand. PX can be oxidized to produce terephthalic acid, a major raw material for the synthesis of polyester fibers and resins.

[0004] Currently, BTX aromatics mainly originate from C6-C8 aromatics in naphtha catalytic reforming oil, cracked gasoline (a byproduct of steam cracking), and coking crude benzene (also known as coke oven light oil). The BTX product is then obtained through processes such as extraction, disproportionation and alkyl transfer, isomerization, adsorption separation, or crystallization separation. To increase PX production, toluene disproportionation and the reaction of toluene with heavy aromatics (C9...) are utilized. + A) Alkyl transfer, benzene and heavy aromatics (C9) + A) Alkyl transfer reactions to produce mixed xylenes and benzenes represent an effective process route for increasing PX production. This route can utilize toluene and C9, C6... 10 Heavy aromatics and polycyclic aromatics cannot be used as raw materials for the production of light aromatics. In alkyl transfer processes, the content of polycyclic aromatics such as naphthalene in the raw materials is strictly limited.

[0005] With the rapid development of the aromatics, olefins, and oil refining industries, China generates tens of millions of tons of low-quality heavy aromatics as byproducts annually. Aside from small amounts used in the production of solvent oils or naphthalene, these raw materials traditionally had to be processed into diesel fuel, with some companies even using them as fuel oil. The main component of these low-quality heavy aromatics is C. 11 +Alkylbenzenes and polycyclic aromatic hydrocarbons (PAHs), primarily naphthalene or naphthalene derivatives, are among the pollutants. With the continuous upgrading of national diesel fuel standards, the permissible PAH content is constantly decreasing, making the rational conversion of large quantities of PAHs an unavoidable problem. For example, light cycle oil (LCO) from catalytic cracking units is a type of low-value-added oil rich in PAH components, with a total aromatic content ranging from 70% to 90%. From a resource utilization perspective, using it as a feedstock to selectively open the rings of PAHs and directly produce BTX is particularly important.

[0006] UOP disclosed the LCO-X process (Multi-zone process for the production of xylene compounds, US20080161622, 2008-07-03; Process for xylene production, WO2009008876, 2009-01-15) for the production of xylene and benzene via LCO hydroconversion-selective alkyl transfer. The process first involves hydrorefining to remove sulfur and nitrogen impurities from the feedstock and selectively saturating the polycyclic aromatic hydrocarbons therein. The feedstock then enters a series of hydrocracking reactors to undergo selective cracking.

[0007] Patent application CN 103221131A (SK New Technology Co., Ltd., Hydrocracking Catalyst for Preparing Valuable Light Aromatic Hydrocarbons from Polycyclic Aromatic Hydrocarbons, 2013.07.24) utilizes a catalyst containing β-zeolite, boehmite, and one or more metals selected from Group VIII and Group VIB metals to produce the maximum amount of BTX from LCO. The metals are sulfides of Co and Mo, and the catalyst Sn is also included. The conversion rate of tetrahydronaphthalene is 99%, and the amount of BTX can reach 84%.

[0008] Patent application CN 103551180A (China National Offshore Oil Corporation, a type of C 10 + A method for preparing a selective hydrogenation cracking catalyst for bicyclic heavy aromatics (February 5, 2014) uses one or both of Y molecular sieve and alumina as supports, one or both of platinum and palladium as main agents, and one or more of lanthanum, cerium, and yttrium as promoters to obtain the catalyst. 10 + The highest conversion rate is 52.5%, and the highest C8 aromatic selectivity is 45.8%.

[0009] Patent application CN 108940354A (China National Offshore Oil Corporation Tianjin Chemical Research and Design Institute Co., Ltd., a type of C 10 +A selective hydrogenation ring-opening catalyst for heavy aromatics and its preparation method (2018.12.07) was prepared by first modifying HY molecular sieve with a SiO2 / Al2O3 molar ratio of 8-13 with ammonium fluorosilicate and platinum-containing solution, then extruding it with alumina, drying and calcining it, and finally impregnating it with an equal volume of platinum-containing solution, drying and calcining it to obtain the catalyst.

[0010] Patent application CN 110465327A (CNOOC Tianjin Chemical Research and Design Institute Co., Ltd., A Highly Active Heavy Aromatic Hydrocarbon Lightening Catalyst and Its Preparation Method, 2019.11.19) discloses a heavy aromatic hydrocarbon lightening catalyst comprising a composite support containing Beta molecular sieve, ZSM-5 molecular sieve, and macroporous alumina or boehmite binder, and precious metal platinum nanoparticles, capable of efficiently processing C under low pressure conditions. 10 + Heavy aromatic hydrocarbons.

[0011] Patent application CN 110075912A (Nanjing University of Technology, a type of C) 10 + Catalysts and their preparation methods for the hydrogenation and dealkylation of heavy aromatics to prepare low-carbon aromatics (August 2, 2019) utilize composite molecular sieves such as mordenite, β-zeolite, ZSM-5 molecular sieve, and Y-zeolite as supports, and one or more transition metal oxides such as MoO3, NiO, Bi2O3, Co3O4, or CuO, as well as rare earth oxides, as active components. 10 + The conversion rate of heavy aromatics can reach up to 42.4%.

[0012] Patent application CN 110075911A (Nanjing University of Technology, a method for C) 10 + A catalyst for the hydrogenation and dealkylation of heavy aromatics and its preparation method (published on August 2, 2019) discloses a catalyst using a modified β-zeolite with a microporous-mesoporous composite structure as a support and transition metal oxides and rare earth oxides as active components. The transition metal oxides are one or more of MoO3, Bi2O3, Co3O4, or CuO, and a mixture of NiO; the rare earth oxides are one or two of La2O3 or CeO2; and the specific surface area of ​​the modified β-zeolite is 290-340 m². 2 / g, pore volume 0.28-0.35cm³ 3 / g.

[0013] Patent application CN 103121906 A (China Petroleum & Chemical Corporation, Method for producing monocyclic aromatic hydrocarbons from polycyclic aromatic hydrocarbons, 2013.05.29) uses a zeolite molecular sieve with abundant internal mesoporous channels and a group VIII metal catalyst. Under hydrogen-dependent fixed-bed reaction conditions of reaction temperature 300-450℃, reaction pressure 2.0-8.0MPa, and hydrogen-hydrocarbon molar ratio of 2-6, the selectivity of monocyclic aromatic hydrocarbons can reach up to 65.8%.

[0014] Patent application CN 112662428A (China Petroleum & Chemical Corporation, C 10 + A method and system for the hydrogenation and lightening of heavy aromatics (April 16, 2021) employs a two-stage conversion scheme. The heavy aromatic feedstock first undergoes selective hydrogenation saturation under mild conditions, and the resulting hydrogenated saturated product is then subjected to hydrocracking. The hydrocracking catalyst includes at least one of mordenite and β-zeolite, as well as oxides of Group VIII and Group VIB metals.

[0015] Coking is a major factor in the deactivation of acidic molecular sieve catalysts. Coking typically covers the active sites or blocks the pores of the molecular sieve, making it difficult for reactant molecules to access the active sites. For molecular sieve catalysts, the biggest consequence of coking is a significant decrease in catalyst activity or even complete deactivation with increasing reaction time (Research Progress on Deactivation Characteristics of Methanol-to-Aromatics Catalysts, *Industrial Catalysis*, 2018, 26(11): 7). Especially for microporous molecular sieves, even a very low amount of coking can cause a significant decrease in catalyst activity. Typically, the maximum amount of coking in deactivated molecular sieve catalysts is around 10-15%.

[0016] Selective ring-opening reactions of fused-ring aromatics are typical In acid-catalyzed reactions, common catalysts are acidic zeolite molecular sieves or metal-modified acidic zeolite molecular sieves. However, existing catalysts suffer from rapid coking and deactivation rates, as well as poor stability. This is mainly due to two reasons: First, polycyclic aromatic hydrocarbons (PAHs) have large molecules and slow diffusion rates, making them highly susceptible to deep dehydrogenation reactions at the acid centers of the catalyst. Second, PAHs are typically the precursors for coking; therefore, using PAHs as feedstocks makes coking more likely, leading to rapid catalyst deactivation.

[0017] Currently, the selective ring-opening catalysts for polycyclic aromatic hydrocarbons (PAHs) used both domestically and internationally are basically limited to molecular sieves with three-dimensional twelve-membered ring channels, such as β-zeolite and γ-zeolite, and supported with noble metals. However, the diffusion performance of these catalysts still falls short of the requirements for rapid diffusion of reactant molecules, resulting in significantly shorter catalyst lifetimes compared to alkyl transfer catalysts. Furthermore, the stability of these catalysts still needs further improvement to meet industrial requirements. The utilization rate of acid centers on the inner surface of the catalyst remains low, leading to low processing capacity and conversion rates for PAHs. While the introduction of hydrogenation metals, especially noble metals, can increase the C-value of the catalyst... 10 + While improving the processing capacity and stability of heavy aromatics, catalysts also suffer from adverse effects such as saturated hydrogenation of aromatic rings, increased aromatic ring loss rate, reduced selectivity of the target product, and decreased benzene quality. Therefore, improving the diffusion performance and carbon holding capacity of the catalyst is key to solving the problems of low catalyst activity and insufficient stability. Summary of the Invention

[0018] The purpose of this invention is to overcome the problems of poor catalyst activity and short catalyst life and poor stability caused by coking in the prior art, and to provide a ring-opening catalyst for polycyclic aromatic hydrocarbons and its preparation method, as well as a method for preparing light aromatic hydrocarbons from polycyclic aromatic hydrocarbons. The catalyst has a high carbon capacity index, high carbon capacity, high catalyst activity, and good stability, and can be used in the industrial production of preparing light aromatic hydrocarbons from polycyclic aromatic hydrocarbons through ring opening.

[0019] To achieve the above objectives, a first aspect of the present invention provides a selective ring-opening catalyst for polycyclic aromatic hydrocarbons, the catalyst comprising β-zeolite, a binder, and a metal active component, wherein the binder content is 15-300 parts by weight relative to 100 parts by weight of β-zeolite, the metal active component content is 0.1-160 parts by weight, and the catalyst has a mesoporous specific surface area of ​​40-500 m². 2 / g, mesopore volume accounts for 30-95% of the total pore volume, and the mesopore volume is 0.1-0.6cm. 3 / g.

[0020] A second aspect of this invention provides a method for preparing a selective ring-opening catalyst for polycyclic aromatic hydrocarbons, the method comprising the following steps:

[0021] (1) The β-zeolite raw powder with a silica / alumina molar ratio of 12-350 is subjected to acid treatment at least once;

[0022] (2) The molecular sieve obtained by acid treatment was subjected to ammonium exchange to obtain ammonium-type β-zeolite;

[0023] (3) The ammonium-type β-zeolite and the binder are molded to obtain the catalyst precursor;

[0024] (4) The catalyst precursor is treated with water vapor containing organic amines;

[0025] The method further includes: introducing a metal active component in step (3), and / or introducing a metal active component after the treatment in step (4).

[0026] A third aspect of the present invention provides a method for preparing light aromatics from polycyclic aromatic hydrocarbons, the method comprising: contacting polycyclic aromatic hydrocarbons and / or selectively saturated products of polycyclic aromatic hydrocarbons with a catalyst under reaction conditions for selective ring-opening of polycyclic aromatic hydrocarbons to prepare light aromatics; wherein the catalyst is the selective ring-opening catalyst for polycyclic aromatic hydrocarbons described in the first aspect or the selective ring-opening catalyst for polycyclic aromatic hydrocarbons prepared by the preparation method described in the second aspect.

[0027] The inventors of this invention have discovered that a composite treatment method, specifically employing first treating the catalyst precursor with an organic acid, followed by sequentially treating it with steam containing ammonia and steam containing organic amines, effectively expands the pores of the catalyst and promotes the formation of a specific mesoporous structure. The catalyst provided by this invention, due to its specific mesoporous structure and specific silicon-to-aluminum ratio, exhibits high activity while also possessing a high carbon capacity (high carbon content) in the industrial production of light aromatics from heavy aromatics. It also demonstrates strong carbon capacity, long catalyst life, and good stability. The catalyst provided by this invention is particularly suitable for C10... + The selective ring-opening reaction of polycyclic aromatic hydrocarbons exhibits excellent conversion rate and stability, thus enabling the smooth completion of the process of preparing light aromatic hydrocarbons from heavy aromatic hydrocarbons. Attached Figure Description

[0028] Figure 1 This is the thermal analysis curve of the catalyst prepared in Example 3 after 960 hours of reaction. Detailed Implementation

[0029] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0030] The first aspect of this invention provides a selective ring-opening catalyst for polycyclic aromatic hydrocarbons, the catalyst comprising β-zeolite, a binder, and a metal active component. The binder content is 15-300 parts by weight relative to 100 parts by weight of β-zeolite, the metal active component content is 0.1-160 parts by weight, and the catalyst has a mesoporous specific surface area of ​​40-500 m². 2 / g, mesopore volume accounts for 30-95% of the total pore volume, and the mesopore volume is 0.1-0.6cm. 3 / g.

[0031] The catalyst provided by this invention has a specific mesoporous structure and a specific catalyst composition, thus exhibiting both high activity and a high carbon capacity index. This results in strong carbon capacity, long catalyst life, and good stability in the industrial production of light aromatics from polycyclic aromatic hydrocarbons through ring-opening.

[0032] In a preferred embodiment, the molar ratio of β-zeolite silica / alumina is 12-350, preferably 15-250, and more preferably 20-160.

[0033] In a preferred embodiment, the binder content is 20-150 parts by weight relative to 100 parts by weight of β-zeolite, and the content of the metal active component is 20-120 parts by weight. The advantage of this preferred embodiment is improved selectivity and stability of the catalyst for selective ring-opening reactions.

[0034] In this invention, there is no particular limitation on the type of binder; binders conventionally defined in the art are all applicable to this invention. Preferably, the binder is selected from at least one of alumina, silica, boehmite, and titanium dioxide, and more preferably alumina. The advantage of this preferred embodiment is that it improves the strength of the catalyst.

[0035] In this invention, the type of metal active component is not particularly limited. Preferably, the metal active component is selected from at least one of Group VB elements, Group VIB elements, and rare earth elements; more preferably, it is a Group VB element and / or a Group VIB element and a rare earth element; even more preferably, it is a Group VB element, a Group VIB element, and a rare earth element. By using the above-mentioned metal active component, the selective ring-opening activity, selectivity, and stability of the catalyst can be improved.

[0036] In this invention, there is no particular limitation on the types of Group VB elements. Preferably, the Group VB element is vanadium and / or niobium, and more preferably niobium.

[0037] In this invention, there is no particular limitation on the types of Group VIB elements. Preferably, the Group VIB element is molybdenum and / or tungsten, and more preferably molybdenum.

[0038] In this invention, there is no particular limitation on the types of rare earth elements; all rare earth elements conventionally defined in the art are applicable to this invention. Preferably, the rare earth element is lanthanum and / or cerium.

[0039] In a preferred embodiment, the content of the Group VB element is 0.1-80 parts by weight, preferably 15-60 parts by weight, relative to 100 parts by weight of β zeolite.

[0040] In a preferred embodiment, the content of the Group VIB element is 0.1-80 parts by weight, preferably 15-60 parts by weight, relative to 100 parts by weight of β-zeolite.

[0041] In a preferred embodiment, the rare earth element content is 0.1-80 parts by weight, preferably 5-20 parts by weight, relative to 100 parts by weight of β-zeolite.

[0042] The advantages of the above preferred embodiments are improved selective ring-opening reaction activity and catalyst stability.

[0043] In a preferred embodiment, the catalyst has a mesoporous specific surface area of ​​40-400 m². 2 / g. Within this numerical range, as a further non-limiting point value example, it could be 80m. 2 / g、120m 2 / g, 160m 2 / g、200m 2 / g、240m 2 / g、280m 2 / g、320m 2 / g、360m 2 / g etc.

[0044] In a preferred embodiment, the mesopore volume of the catalyst accounts for 30-90% of the total pore volume, more preferably 30-80%.

[0045] In a preferred embodiment, the catalyst has a mesopore volume of 0.1-0.6 cm³. 3 / g, further preferably 0.25-0.6cm 3 / g.

[0046] Existing catalysts for the conversion of polycyclic aromatic hydrocarbons (PAHs) typically include an acidic component with cracking capabilities and a hydrogenation component. Generally, due to poor diffusion performance, they are prone to coking and deactivation, resulting in short catalyst lifetimes. The hydrogenation component is usually located on the outer surface of the catalyst, making it difficult to synergize with the acidic sites in the molecular sieve channels, thus leading to low selectivity in the selective ring-opening reaction and a tendency for over-cracking. Furthermore, PAHs have large molecular sizes; for example, phenanthrene molecules are 0.79 nm and pyrene molecules are 0.9 nm, meaning they can only react on the outer surface of the catalyst, significantly reducing catalytic efficiency and resulting in low catalyst activity. The catalyst provided in this invention has a large specific surface area (preferably 40-400 m²). 2 / g) and mesopore volume (preferably 0.25-0.6 cm³). 3The specific surface area of ​​the catalyst is larger (approximately 30-80% of the total pore volume), while in the prior art, although the catalyst has a larger specific surface area, the mesopore volume is typically less than 0.05 cm³. 3 / g, the mesopore volume accounts for about 5-10% of the total pore volume, which is not conducive to the diffusion and reaction of polycyclic aromatic hydrocarbons.

[0047] In this invention, the mesopore specific surface area, mesopore volume, and total pore volume are obtained by low-temperature nitrogen adsorption measurement. The specific testing method is as follows: at a liquid nitrogen temperature of 77K, a physical adsorption apparatus is used at a relative pressure of 10... -3 Nitrogen adsorption experiments were conducted within a temperature range of -1°C to obtain adsorption isotherms. Based on the desorption branch of the adsorption isotherm, the mesopore distribution of the sample was analyzed using the BJH independent cylinder model; the mesopore volume and micropore volume were measured using the t-curve method. The mesopore specific surface area was obtained using linear regression with the BET model.

[0048] According to the present invention, the selective ring-opening catalyst for polycyclic aromatic hydrocarbons has a high carbon capacity index. Preferably, the carbon capacity index of the catalyst, as determined by thermal analysis, is not less than 15%, more preferably 25-50%. In contrast, the carbon capacity index of catalysts in the prior art is generally around 10%.

[0049] In this invention, the carbon deposition index refers to the ratio of the amount of coke deposited on the catalyst to the mass of the catalyst after the reaction, measured by thermal analysis, when the conversion rate of the reactants is 30% of the initial conversion rate of the fresh catalyst, multiplied by 100%. The amount of coke deposited on the catalyst was tested using a TA Instruments SDTQ600 integrated thermal analyzer. The test method involved heating the catalyst from room temperature to 1073 K in an air atmosphere at a heating rate of 10 K·min. -1 The amount of coke deposited is defined as the weight loss of the catalyst in the K range of 473-1073 K.

[0050] A second aspect of this invention provides a method for preparing a selective ring-opening catalyst for polycyclic aromatic hydrocarbons, the method comprising the following steps:

[0051] (1) The β-zeolite raw powder with a silica / alumina molar ratio of 12-350 is subjected to acid treatment at least once;

[0052] (2) The molecular sieve obtained by acid treatment was subjected to ammonium exchange to obtain ammonium-type β-zeolite;

[0053] (3) The ammonium-type β-zeolite and the binder are molded to obtain the catalyst precursor;

[0054] (4) The catalyst precursor is treated with water vapor containing organic amines;

[0055] The method further includes: introducing a metal active component in step (3), and / or introducing a metal active component after the treatment in step (4).

[0056] In a particularly preferred embodiment, the silica / alumina molar ratio of the β-zeolite powder is 15-250, more preferably 20-160. The advantage of this preferred embodiment is that it ensures the catalyst has a certain number of acidic sites.

[0057] According to the preparation method of the present invention, acid treatment is used to adjust the acidity and unclog the pores, and to a certain extent, it also has the effect of creating mesopores, thereby improving the diffusion of reactant molecules and increasing the carbon capacity index of the catalyst. Preferably, in step (1), the β-zeolite powder is subjected to acid treatment at least once with organic acid.

[0058] In this invention, preferably, the acid treatment in step (1) includes contacting β-zeolite with an acid solution.

[0059] In a particularly preferred embodiment, the acid treatment is performed 1-4 times, more preferably 1-2 times. This preferred approach of multiple acid treatments allows for control of the amount of aluminum removed from the molecular sieve and optimization of the molecular sieve pore structure.

[0060] In a preferred embodiment, after the first acid treatment, solid-liquid separation (e.g., filtration) is performed to obtain a filter cake, which is then dried before a second acid treatment.

[0061] According to the preparation method of the present invention, there are no restrictions on the drying conditions during the acid treatment process. Preferably, the drying conditions include: a drying temperature of 100-150°C and a drying time of 1-20 hours.

[0062] In this invention, there are no particular restrictions on the type of acid used in the acid treatment in step (1), as long as it is beneficial to the formation of mesopores. Preferably, the organic acid is selected from at least one of citric acid, acetic acid, glycolic acid, oxalic acid, and ethylenediaminetetraacetic acid, and more preferably at least one of citric acid, glycolic acid, and ethylenediaminetetraacetic acid. By using organic acid for acid treatment, the loss of crystallinity of the molecular sieve can be avoided.

[0063] In this invention, the concentration range of the acid solution used for the acid treatment in step (1) is relatively wide. Preferably, the concentration of the acid solution is 0.2-4.5 mol / L.

[0064] In this invention, there is no particular limitation on the amount of organic acid solution used, as long as the β zeolite powder is completely in contact with the organic acid solution. It can be understood that in this case, the β zeolite powder is completely immersed in the acid solution.

[0065] According to the preparation method of the present invention, preferably, the acid treatment conditions include: a temperature of 50-90°C and a time of 2-15 hours.

[0066] In this invention, there are no restrictions on the ammonium exchange in step (2). Any existing ammonium exchange method can be used, as long as it can convert the molecular sieve obtained by acid treatment into an ammonium-type molecular sieve. For example, according to a preferred embodiment of the present invention, the ammonium exchange in step (2) includes contacting the molecular sieve obtained by acid treatment with an aqueous solution of ammonium salt.

[0067] In a preferred embodiment, the ammonium exchange can be performed once or multiple times, and those skilled in the art can choose according to actual needs.

[0068] In a preferred embodiment, the ammonium exchange conditions include a temperature of 80-100°C and a time of 1-10 hours.

[0069] In a preferred embodiment, the liquid-to-solid weight ratio of the ammonium exchange is 1-10:1. It is understood that the liquid-to-solid weight ratio refers to the weight ratio of the ammonium salt aqueous solution to the molecular sieve obtained from acid treatment.

[0070] In a preferred embodiment, the concentration of ammonium salt in the ammonium salt aqueous solution is 0.5-1.5 mol / L.

[0071] In a preferred embodiment, the ammonium salt used in the ammonium salt aqueous solution is selected from at least one of ammonium nitrate, ammonium sulfate, ammonium chloride, and ammonium acetate.

[0072] According to the preparation method of the present invention, preferably, step (2) further includes: after the ammonium exchange, performing solid-liquid separation to obtain a filter cake, and then drying the filter cake. Preferably, the drying conditions include: a temperature of 100-150°C and a time of 2-12 hours.

[0073] In this invention, there are no particular limitations on the amount of ammonium β-zeolite and the amount of binder, as long as the catalyst requirements are met. Preferably, in step (3), the amount of binder is 15-300 parts by weight relative to 100 parts by weight of ammonium β-zeolite, and more preferably 20-150 parts by weight.

[0074] In this invention, the types of adhesives have already been described in the first aspect and will not be repeated here.

[0075] According to the preparation method of the present invention, there is no limitation on the molding method, as long as it can produce a catalyst with the desired shape. Preferably, the molding includes mixing ammonium β-zeolite, a binder, and optionally an extrusion molding aid, followed by extrusion molding, drying, and calcination.

[0076] According to the preparation method of the present invention, preferably, the amount of extrusion molding aid is 1-30 parts by weight relative to 100 parts by weight of ammonium β-zeolite.

[0077] In this invention, those skilled in the art can rationally select the type and amount of extrusion molding aids according to the specific circumstances of extrusion molding, and can achieve considerable technical effects without having to expend creative effort.

[0078] In this invention, extrusion molding aids conventionally defined in the art are all applicable. Preferably, the extrusion molding aid is selected from at least one of guar gum powder, dextrin, and methylcellulose.

[0079] In this invention, there are no particular restrictions on the drying conditions during the molding process in step (3), and conventional drying conditions in the art can be used. Preferably, the drying conditions include: a temperature of 80-150°C and a time of 1-10 hours.

[0080] In this invention, there are no particular limitations on the roasting conditions. Preferably, the roasting conditions include a temperature of 200-600℃ and a time of 3-10 hours; more preferably, the temperature is 250-580℃ and the time is 4-8 hours.

[0081] In this invention, step (4) only requires contact between water vapor containing organic amines and the catalyst precursor; the specific method of providing the water vapor containing organic amines and the form of contact with the catalyst precursor are not particularly limited. Preferably, the treatment of the ammonium molecular sieve with water vapor containing organic amines in step (4) includes: contacting an aqueous solution containing organic amines with the catalyst precursor under conditions that satisfy the vaporization of organic amines and water. In this preferred embodiment, the specific operation can be to introduce an aqueous solution containing organic amines into a container containing the catalyst precursor, and then heat it to vaporize the organic amines and water.

[0082] According to the preparation method of the present invention, the range of organic amines that can be selected is relatively wide. Preferably, the organic amine is selected from at least one of methylamine, ethylamine, dimethylamine, and trimethylamine, and more preferably from at least one of methylamine, ethylamine, and dimethylamine. This preferred embodiment is more conducive to generating a mesoporous pore distribution.

[0083] In a preferred embodiment, the organic amine in the aqueous solution contains 10-80% by weight, more preferably 10-50%. This preferred embodiment is more advantageous for controlling the pore distribution of the mesopores.

[0084] According to the present invention, preferably, the contact conditions include: a temperature of 100-600°C, more preferably 200-500°C, and even more preferably 250-500°C; a time of 2-12 hours, preferably 4-10 hours; and a mass hourly space velocity (MSV) of 1-15 h⁻¹ for the aqueous solution containing the organic amine. -1 Preferably 1-8h -1 This preferred embodiment is more advantageous in increasing the ratio of mesopore volume to total pore volume.

[0085] The above contact conditions can satisfy the vaporization of organic amines and water, allowing the organic amines to evaporate and vaporize together with the water, thus enabling sufficient dealumination of the catalyst precursor and facilitating the formation of mesopores.

[0086] According to the preparation method of the present invention, the order of introduction of the metal active component is not particularly limited. It can be introduced in step (3), in step (4), or simultaneously in steps (3) and (4). When introducing the metal active component in step (3), it can also include two methods: a kneading method and an impregnation method. In a preferred embodiment, the introduction of the metal active component in step (3) includes: molding ammonium β-zeolite, binder, and metal active component precursor. Specifically, it can be prepared by the following kneading method: mixing ammonium β-zeolite, binder, and optionally extrusion molding aid, mixing evenly, then adding a salt solution containing the metal active component, mixing evenly, and then extruding, drying, and calcining to obtain the catalyst precursor. In the present invention, the molding method has been described above and will not be repeated here. In another preferred embodiment, the active component is introduced into the catalyst precursor by impregnation. Impregnation methods conventionally defined in the art are applicable to the present invention, such as co-impregnation, stepwise impregnation, and equal-volume impregnation. Preferably, the catalyst precursor is impregnated with a solution containing a precursor of a metal active component, followed by drying and calcination. When there are two or more metal active components, it is preferable to introduce the active components by co-impregnation. Specifically, it can be prepared by impregnating the catalyst precursor with a solution containing a precursor of a metal active component, followed by drying and calcination. The drying and calcination conditions in this embodiment are the same as described above and will not be repeated here.

[0087] According to the present invention, when the metal active component is introduced in step (4), it is preferably done in the following manner. Preferably, the introduction of the metal active component in step (4) includes: after the treatment, introducing the metal active component into the product obtained by impregnation. The conditions of the impregnation method in this embodiment are the same as those described in step (3), and will not be repeated here.

[0088] In a preferred embodiment, the amount of the metal active component relative to 100 parts by weight of ammonium β-zeolite is 0.1-160 parts by weight, more preferably 20-120 parts by weight. The advantage of this preferred embodiment is that it better leverages the synergistic effect between the metal and the acidic site, thereby improving the selectivity of the selective ring-opening reaction.

[0089] In this invention, the types of active metal components have been described in the first aspect and will not be repeated here.

[0090] According to the preparation method of the present invention, the active metal component is provided by its precursor compound. Preferably, the vanadium precursor is selected from at least one of vanadium oxysulfate, vanadium trichloride, ammonium metavanadate, vanadium isopropoxide, and vanadium oxalate. Preferably, the niobium precursor is selected from at least one of niobium oxalate, niobic acid, and niobium pentoxide. Preferably, the molybdenum precursor is selected from at least one of ammonium heptamolybdate, ammonium tetramolybdate, sodium molybdate, molybdenum acetylacetonate, and molybdenum naphthenate. Preferably, the tungsten precursor is selected from at least one of sodium tungstate, ammonium tungstate, ammonium metatungstate, and tungsten chloride. Preferably, the rare earth element precursor is selected from water-soluble salts of each, for example, the lanthanum precursor is selected from at least one of lanthanum nitrate, lanthanum sulfate, lanthanum chloride, lanthanum acetate, lanthanum carbonate, and lanthanum oxalate.

[0091] In a preferred embodiment, the content of the Group VB element is 0.1-80 parts by weight, preferably 15-60 parts by weight, relative to 100 parts by weight of β zeolite.

[0092] In a preferred embodiment, the content of the Group VIB element is 0.1-80 parts by weight, preferably 15-60 parts by weight, relative to 100 parts by weight of β-zeolite.

[0093] In a preferred embodiment, the rare earth element content is 0.1-80 parts by weight, preferably 5-20 parts by weight, relative to 100 parts by weight of β-zeolite.

[0094] The advantages of adopting the above-mentioned preferred embodiments are that they leverage the synergistic effect of the metal and the acidic sites of the molecular sieve to improve the selectivity, activity, and stability of the selective ring-opening reaction.

[0095] Preferably, the method further includes treating the catalyst precursor with ammonia-containing steam before treating the catalyst precursor with water vapor containing organic amine in step (4).

[0096] According to the preparation method of the present invention, as long as ammonia-containing water vapor can be contacted with the catalyst precursor, the specific method of providing the ammonia-containing water vapor and the contact form with the catalyst precursor are not particularly limited. In a preferred embodiment, the treatment of the catalyst precursor with ammonia-containing water vapor includes: contacting the catalyst precursor with an aqueous solution of ammonia-containing water under conditions that satisfy ammonia and water vaporization. In this preferred embodiment, the specific operation may be to introduce an aqueous solution of ammonia-containing water into a container containing the catalyst precursor, and then heat it to vaporize the ammonia and water.

[0097] In this invention, the concentration of ammonia is not particularly limited. Preferably, the weight content of ammonia in the aqueous solution is 5-25%, more preferably 10-20%.

[0098] In this invention, there are no particular limitations on the contact conditions between ammonia and the catalyst precursor. Preferably, the contact conditions include: a temperature of 200-600℃, more preferably 250-550℃; a time of 1-12 h, more preferably 2-10 h; and a mass hourly space velocity (MSV) of 0.5-10 h⁻¹ for the ammonia-containing aqueous solution. -1 Preferably 1-6h -1 .

[0099] According to a particularly preferred embodiment of the present invention, a selective ring-opening catalyst for polycyclic aromatic hydrocarbons is prepared by the following method: (1) β-zeolite raw powder with a silica / alumina molar ratio of 12-350 is subjected to acid treatment at least once with organic acid; (2) the molecular sieve obtained by acid treatment is subjected to ammonium exchange to obtain ammonium-type β-zeolite; (3) the ammonium-type β-zeolite, alumina binder and extrusion molding aid are mixed, the alumina binder is 15-300 parts by weight and the extrusion molding aid is 1-30 parts by weight, after being mixed evenly, salt solutions containing Group VB elements, Group VIB elements and rare earth elements are added respectively, mixed evenly, and then extruded, dried and calcined to obtain a catalyst precursor; (4) the catalyst precursor is treated with water vapor containing ammonia; (5) the catalyst precursor is treated with water vapor containing organic amine to obtain a selective ring-opening catalyst for polycyclic aromatic hydrocarbons.

[0100] A third aspect of the present invention provides a method for preparing light aromatics from polycyclic aromatic hydrocarbons, the method comprising:

[0101] Under the reaction conditions for the selective ring-opening of polycyclic aromatic hydrocarbons to prepare light aromatic hydrocarbons, polycyclic aromatic hydrocarbons and / or selectively saturated products of polycyclic aromatic hydrocarbons are contacted with a catalyst; the catalyst is the selective ring-opening catalyst for polycyclic aromatic hydrocarbons described in the first aspect or the selective ring-opening catalyst for polycyclic aromatic hydrocarbons prepared by the preparation method described in the second aspect.

[0102] In this invention, preferably, in the process of preparing light aromatics from polycyclic aromatic hydrocarbons (PAHs), the PAHs can be directly converted into light aromatics through a one-step selective ring-opening reaction, or they can first undergo a hydrogenation reaction to obtain a selectively saturated product, and then undergo a selective ring-opening reaction to obtain light aromatics. More preferably, the PAHs are first hydrogenated to obtain a selectively saturated product, and then undergo a selective ring-opening reaction to obtain light aromatics. In this invention, the selectively saturated product refers to the PAH that first undergoes a partial hydrogenation saturation reaction to generate an aromatic hydrocarbon retaining only one benzene ring. Preferably, naphthalene undergoes a partial hydrogenation saturation reaction to generate tetrahydronaphthalene. The hydrogenation saturation reaction is a conventionally defined method in the art and will not be described in detail here. Using a selective saturated product ring-opening reaction to obtain light aromatics has the advantages of high selectivity and less catalyst coking.

[0103] In a preferred embodiment, the polycyclic aromatic hydrocarbon has 10-20 carbon atoms, more preferably 10-18. The advantage of this preferred embodiment is that it allows for the conversion of more inferior polycyclic aromatic hydrocarbons.

[0104] In a preferred embodiment, the polycyclic aromatic hydrocarbon is selected from at least one of naphthalene, methylnaphthalene, fluorene, phenanthrene, anthracene, and pyrene, and more preferably at least one of naphthalene, methylnaphthalene, phenanthrene, and anthracene. The advantage of this preferred embodiment is that it improves the conversion rate of the polycyclic aromatic hydrocarbon.

[0105] In a preferred embodiment, the reaction conditions for the selective ring-opening of polycyclic aromatic hydrocarbons to prepare light aromatic hydrocarbons include: a temperature of 300-500℃, a pressure of 0.1-8 MPa, and a mass hourly space velocity of 1-10 h⁻¹. -1 More preferably, the temperature is 320-480℃, the pressure is 1-7MPa, and the mass hourly space velocity is 0.5-6h. -1 .

[0106] Unless otherwise specified, all pressures described in this invention are in gauge pressure.

[0107] In a preferred embodiment, the method further includes introducing hydrogen gas, and the contact conditions are preferably carried out in the presence of hydrogen gas. The introduction of hydrogen gas can increase catalyst lifetime.

[0108] In this invention, the range of hydrogen usage is relatively wide. Preferably, the volume ratio of hydrogen to polycyclic aromatic hydrocarbons is 400-4000:1.

[0109] Using the selective ring-opening catalyst for polycyclic aromatic hydrocarbons provided by this invention in the reaction of polycyclic aromatic hydrocarbons to prepare light aromatic hydrocarbons is more conducive to improving the conversion rate of polycyclic aromatic hydrocarbons and the selectivity of light aromatic hydrocarbons, and the catalyst has good stability.

[0110] The present invention will be described in detail below through embodiments.

[0111] In the following examples, the mesoporous specific surface area, mesoporous pore volume (also known as mesoporous volume), and total pore volume were determined using a low-temperature nitrogen adsorption method. The test method was as follows: at a liquid nitrogen temperature of 77K, a physical adsorption apparatus was used at a relative pressure of 10... -3 Nitrogen adsorption experiments were conducted within a temperature range of -1°C to obtain adsorption isotherms. Based on the desorption branches of the adsorption isotherms, the mesopore distribution of the samples was analyzed using the BJH independent cylinder model; the mesopore volume and micropore volume were measured using the t-curve method. The mesopore specific surface area was obtained using linear regression with the BET model.

[0112] The carbon deposition index, determined by thermal analysis, is the ratio of the amount of coke deposited on the catalyst to the mass of the catalyst after the reaction when the conversion rate of the reactant (aromatics) is 30% of the initial conversion rate of the fresh catalyst, multiplied by 100%. The amount of coke deposited on the catalyst was tested using a TA Instruments SDTQ600 integrated thermal analyzer. The test method involved heating the catalyst from room temperature to 1073 K in an air atmosphere at a rate of 10 K·min. -1 The amount of coke deposited is defined as the weight loss of the catalyst in the K range of 473-1073 K.

[0113] The formulas for calculating the mass conversion rate of polycyclic aromatic hydrocarbons and the mass selectivity of light aromatic hydrocarbons (light aromatic hydrocarbons refer to C6-C8 aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene) are as follows:

[0114]

[0115]

[0116] Example 1

[0117] 1. Catalyst Preparation

[0118] (1) Sodium-type β-zeolite powder (SiO2 / Al2O3 molar ratio of 20) was completely contacted with 2 mol / L citric acid solution and treated at 80℃ for 4 hours. Then, solid-liquid separation was performed, and the resulting filter cake was dried at 120℃ for 3 hours.

[0119] The dried filter cake was subjected to a second acid treatment, which involved complete contact with a 2 mol / L citric acid solution and treatment at 80°C for 4 hours. Solid-liquid separation was then performed, and the resulting filter cake was dried at 120°C for 3 hours to obtain acid-treated β-zeolite molecular sieve S1-A.

[0120] (2) S1-A was exchanged twice with an ammonium salt aqueous solution (ammonium nitrate, ammonium salt concentration of 1 mol / L) (each exchange was at 85℃ for 3 hours; after the first exchange, solid-liquid separation was performed, and the filter cake was dried at 120℃ for 3 hours, and then the same ammonium salt aqueous solution was used for the second exchange). The liquid-solid weight ratio was 5:1. After solid-liquid separation, the filter cake was dried at 120℃ for 3 hours to obtain ammonium type β zeolite molecular sieve S1-B.

[0121] (3) Mix 100 parts by weight of ammonium type β zeolite molecular sieve S1-B, 40 parts by weight of alumina binder and 15 parts by weight of extrusion molding aid guar powder. After mixing thoroughly, add 15 parts by weight of ammonium heptamolybdate solution containing Mo and 20 parts by weight of lanthanum nitrate solution containing La respectively. After mixing thoroughly, extrude into strips, dry at 120°C for 3 hours, and calcine at 550°C in air atmosphere for 4 hours to obtain catalyst precursor S1-C.

[0122] (4) The catalyst precursor S1-C was treated with ammonia-containing steam (specifically, an aqueous solution containing 20% ​​by weight of ammonia was contacted with S1-C at a temperature of 250°C for 10 hours, and the mass hourly space velocity of the ammonia solution was 1 h⁻¹). -1 ), thus obtaining catalyst precursor S1-D.

[0123] (5) The catalyst precursor S1-D was treated with ethylamine-containing water vapor (specifically, an aqueous solution containing 18% by weight of ethylamine was contacted with S1-D at a temperature of 450°C for 4 hours, and the mass hourly space velocity of the ethylamine aqueous solution was 4 h⁻¹). -1 ), thus obtaining S1, a selective ring-opening catalyst for fused-ring aromatics.

[0124] The pore structure parameters of catalyst S1, determined by the low-temperature nitrogen adsorption method, are shown in Table 1.

[0125] 2. Catalyst Evaluation

[0126] Fixed-bed reactor volume: 50 ml;

[0127] Catalyst loading: 15 ml;

[0128] Raw material: Tetrahydronaphthalene (a selectively saturated product obtained by selective hydrogenation of naphthalene);

[0129] Reaction temperature: 380℃;

[0130] Reaction pressure: 4.0 MPa;

[0131] Liquid hourly space velocity (LHSV) of tetrahydronaphthalene: 4.0 h⁻¹ -1 ;

[0132] The volume ratio of hydrogen to tetrahydronaphthalene is 1000:1.

[0133] In a fixed-bed reactor, tetrahydronaphthalene and hydrogen were contacted with the prepared polycyclic aromatic hydrocarbon selective ring-opening catalyst S1. The resulting reaction product was cooled by an air condenser and separated by a gas-liquid separator to obtain a liquid product. Samples of the liquid product were taken for analysis every 12 hours.

[0134] After 96 hours of reaction, the conversion rate of tetrahydronaphthalene was calculated to be 85.4%, and the selectivity for light aromatic hydrocarbons (benzene, toluene, xylene, ethylbenzene) was 65.8%.

[0135] 3. Determination of catalyst carbon capacity index

[0136] After 852 hours of reaction, the conversion rate of catalyst S1 decreased to 30% of the initial conversion rate of fresh catalyst. Thermal analysis results showed that the carbon tolerance index of catalyst S1 was 35.6%.

[0137] Comparative Example 1

[0138] 1. Catalyst Preparation

[0139] (1) Sodium-type β-zeolite raw powder (SiO2 / Al2O3 molar ratio of 20) was exchanged twice with ammonium salt aqueous solution (ammonium nitrate, ammonium salt concentration of 1 mol / L) (each exchange temperature was 85℃ and time was 3h; after the first exchange, solid-liquid separation was performed, and the filter cake was dried at 120℃ for 3 hours, and then the same ammonium salt aqueous solution was used for the second exchange). The liquid-solid weight ratio was 5:1. Solid-liquid separation was performed, and the filter cake was dried at 120℃ for 3 hours to obtain ammonium-type β-zeolite molecular sieve B1-A.

[0140] (2) Mix 100 parts by weight of ammonium type β zeolite molecular sieve B1-A, 40 parts by weight of alumina binder and 15 parts by weight of extrusion molding aid guar powder. After mixing thoroughly, add 15 parts by weight of ammonium heptamolybdate solution containing Mo and 20 parts by weight of lanthanum nitrate solution containing La respectively. After mixing thoroughly, extrude into strips, dry at 120°C for 3 hours, and calcine at 550°C in air for 4 hours to obtain catalyst B1.

[0141] The pore structure parameters of catalyst B1, determined by the low-temperature nitrogen adsorption method, are shown in Table 1.

[0142] 2. Catalyst Evaluation

[0143] Fixed-bed reactor volume: 50 ml;

[0144] Catalyst loading: 15 ml;

[0145] Raw material: Tetrahydronaphthalene (a selectively saturated product obtained by selective hydrogenation of naphthalene);

[0146] Reaction temperature: 380℃;

[0147] Reaction pressure: 4.0 MPa;

[0148] Liquid hourly space velocity (LHSV) of tetrahydronaphthalene: 4.0 h⁻¹ -1 ;

[0149] The volume ratio of hydrogen to tetrahydronaphthalene is 1000:1.

[0150] In a fixed-bed reactor, tetrahydronaphthalene and hydrogen were contacted with the catalyst B1 prepared above. The resulting reaction product was cooled by an air condenser and separated by a gas-liquid separator to obtain a liquid product. Samples of the liquid product were taken for analysis every 12 hours.

[0151] The catalyst deactivates rapidly. After 96 hours of reaction, the conversion rate of tetrahydronaphthalene was calculated to be 16.7%, and the selectivity for light aromatics (benzene, toluene, xylene, ethylbenzene) was 41.5%.

[0152] 3. Determination of catalyst carbon capacity index

[0153] After 96 hours of reaction, the conversion rate of catalyst B1 decreased to 30% of the initial conversion rate of fresh catalyst. Thermal analysis results showed that the carbon tolerance index of catalyst B1 was 11.4%.

[0154] Comparative Example 2

[0155] 1. Catalyst Preparation

[0156] (1) Sodium-type β-zeolite powder (SiO2 / Al2O3 molar ratio of 20) was completely contacted with 2 mol / L citric acid solution and treated at 80℃ for 4 hours. Then, solid-liquid separation was performed, and the resulting filter cake was dried at 120℃ for 3 hours.

[0157] The dried filter cake was subjected to a second acid treatment, which involved complete contact with a 2 mol / L citric acid solution and treatment at 80°C for 4 hours. Solid-liquid separation was then performed, and the resulting filter cake was dried at 120°C for 3 hours to obtain acid-treated β-zeolite molecular sieve B2-A.

[0158] (2) B2-A was exchanged twice with an ammonium salt aqueous solution (ammonium nitrate, ammonium salt concentration of 1 mol / L) (each exchange was at 85℃ for 3 hours; after the first exchange, solid-liquid separation was performed, and the filter cake was dried at 120℃ for 3 hours, and then the same ammonium salt aqueous solution was used for the second exchange). The liquid-solid weight ratio was 5:1. After solid-liquid separation, the filter cake was dried at 120℃ for 3 hours to obtain ammonium type β zeolite molecular sieve B2-B.

[0159] (3) Mix 100 parts by weight of ammonium type β zeolite molecular sieve B2-B, 40 parts by weight of alumina binder and 15 parts by weight of extrusion molding aid guar powder. After mixing thoroughly, add 15 parts by weight of ammonium heptamolybdate solution containing Mo and 20 parts by weight of lanthanum nitrate solution containing La respectively. After mixing thoroughly, extrude into strips, dry at 120°C for 3 hours, and calcine at 550°C in air atmosphere for 4 hours to obtain catalyst B2.

[0160] The pore structure parameters of catalyst B2, determined by the low-temperature nitrogen adsorption method, are shown in Table 1.

[0161] 2. Catalyst Evaluation

[0162] Fixed-bed reactor volume: 50 ml;

[0163] Catalyst loading: 15 ml;

[0164] Raw material: Tetrahydronaphthalene (a selectively saturated product obtained by selective hydrogenation of naphthalene);

[0165] Reaction temperature: 380℃;

[0166] Reaction pressure: 4.0 MPa;

[0167] Liquid hourly space velocity (LHSV) of tetrahydronaphthalene: 4.0 h⁻¹ -1 ;

[0168] The volume ratio of hydrogen to tetrahydronaphthalene is 1000:1.

[0169] In a fixed-bed reactor, tetrahydronaphthalene and hydrogen were contacted with the catalyst B2 prepared above. The resulting reaction product was cooled by an air condenser and separated by a gas-liquid separator to obtain a liquid product. Samples of the liquid product were taken for analysis every 12 hours.

[0170] After 96 hours of reaction, the conversion rate of tetrahydronaphthalene was calculated to be 25.8%, and the selectivity for light aromatic hydrocarbons (benzene, toluene, xylene, ethylbenzene) was 44.3%.

[0171] 3. Determination of catalyst carbon capacity index

[0172] After 144 hours of reaction, the conversion rate of catalyst B2 decreased to 30% of the initial conversion rate of fresh catalyst. Thermal analysis results showed that the carbon tolerance index of catalyst B2 was 12.1%.

[0173] Comparative Example 3

[0174] 1. Catalyst Preparation

[0175] (1) Sodium-type β-zeolite powder (SiO2 / Al2O3 molar ratio of 20) was completely contacted with 2 mol / L citric acid solution and treated at 80℃ for 4 hours. Then, solid-liquid separation was performed, and the resulting filter cake was dried at 120℃ for 3 hours.

[0176] The dried filter cake was subjected to a second acid treatment, which involved complete contact with a 2 mol / L citric acid solution and treatment at 80°C for 4 hours. Solid-liquid separation was then performed, and the resulting filter cake was dried at 120°C for 3 hours to obtain acid-treated β-zeolite molecular sieve B3-A.

[0177] (2) B3-A was exchanged twice with an ammonium salt aqueous solution (ammonium nitrate, ammonium salt concentration of 1 mol / L) (each exchange was at a temperature of 85℃ and a time of 3 h; after the first exchange, solid-liquid separation was performed, and the filter cake was dried at 120℃ for 3 hours, and then the same ammonium salt aqueous solution was used for the second exchange). The liquid-solid weight ratio was 5:1. After solid-liquid separation, the filter cake was dried at 120℃ for 3 hours to obtain ammonium type β zeolite molecular sieve B3-B.

[0178] (3) Mix 100 parts by weight of ammonium type β zeolite molecular sieve B3-B, 40 parts by weight of alumina binder and 15 parts by weight of extrusion molding aid guar powder. After mixing thoroughly, add 15 parts by weight of ammonium heptamolybdate solution containing Mo and 20 parts by weight of lanthanum nitrate solution containing La respectively. After mixing thoroughly, extrude into strips, dry at 120°C for 3 hours, and calcine at 550°C in air for 4 hours to obtain catalyst precursor B3-C.

[0179] (4) The catalyst precursor B3-C was treated with ammonia-containing steam (specifically, an aqueous solution containing 20% ​​by weight of ammonia was contacted with B3-C at a temperature of 250°C for 10 hours, and the mass hourly space velocity of the ammonia solution was 1 h⁻¹). -1 Catalyst B3 was obtained.

[0180] Table 1 shows the pore structure parameters of catalyst B3 determined by the low-temperature nitrogen adsorption method.

[0181] 2. Catalyst Evaluation

[0182] Fixed-bed reactor volume: 50 ml;

[0183] Catalyst loading: 15 ml;

[0184] Raw material: Tetrahydronaphthalene (a selectively saturated product obtained by selective hydrogenation of naphthalene);

[0185] Reaction temperature: 380℃;

[0186] Reaction pressure: 4.0 MPa;

[0187] Liquid hourly space velocity (LHSV) of tetrahydronaphthalene: 4.0 h⁻¹ -1 ;

[0188] The volume ratio of hydrogen to tetrahydronaphthalene is 1000:1.

[0189] In a fixed-bed reactor, tetrahydronaphthalene and hydrogen were contacted with the catalyst B3 prepared above. The resulting reaction product was cooled by an air condenser and separated by a gas-liquid separator to obtain a liquid product. Samples of the liquid product were taken for analysis every 12 hours.

[0190] After 96 hours of reaction, the conversion rate of tetrahydronaphthalene was calculated to be 37.6%, and the selectivity for light aromatic hydrocarbons (benzene, toluene, xylene, ethylbenzene) was 48.1%.

[0191] 3. Determination of catalyst carbon capacity index

[0192] After 240 hours of reaction, the conversion rate of catalyst B3 decreased to 30% of the initial conversion rate of fresh catalyst. Thermal analysis results showed that the carbon tolerance index of catalyst B3 was 13.2%.

[0193] Example 2

[0194] 1. Catalyst Preparation

[0195] (1) Sodium-type β-zeolite powder (SiO2 / Al2O3 molar ratio of 104) was completely contacted with 0.5 mol / L ethylenediaminetetraacetic acid solution and treated at 90°C for 4 hours. Then, solid-liquid separation was performed, and the resulting filter cake was dried at 120°C for 3 hours.

[0196] The dried filter cake was subjected to a second acid treatment, and was completely contacted again with a 0.5 mol / L ethylenediaminetetraacetic acid solution. It was treated at 90°C for 4 hours, followed by solid-liquid separation. The resulting filter cake was dried at 120°C for 3 hours to obtain acid-treated β-zeolite molecular sieve S2-A.

[0197] (2) S2-A was exchanged twice with an ammonium salt aqueous solution (ammonium nitrate and ammonium chloride, with an ammonium salt concentration of 0.5 mol / L) (each exchange was performed at a temperature of 95°C for 4 hours; after the first exchange, solid-liquid separation was carried out, and the filter cake was dried at 120°C for 3 hours, and then the same ammonium salt aqueous solution was used for the second exchange). The liquid-solid weight ratio was 6:1. After solid-liquid separation, the filter cake was dried at 120°C for 3 hours to obtain ammonium type β zeolite molecular sieve S2-B.

[0198] (3) Mix 100 parts by weight of ammonium type β zeolite molecular sieve S2-B, 100 parts by weight of alumina binder and 30 parts by weight of extrusion molding aid guar powder, knead thoroughly and evenly, then add ammonium heptamolybdate solution containing 60 parts by weight of Mo and lanthanum nitrate solution containing 60 parts by weight of La respectively, mix evenly and then extrude and mold, dry at 120°C for 3 hours, and calcine at 550°C in air atmosphere for 4 hours to obtain catalyst precursor S2-C.

[0199] (4) The catalyst precursor S2-C was treated with ammonia-containing steam (specifically, an aqueous solution containing 10% by weight of ammonia was contacted with S2-C at a temperature of 450°C for 2 hours, and the mass hourly space velocity of the ammonia solution was 2 h⁻¹). -1 ), thus obtaining catalyst precursor S2-D.

[0200] (5) The catalyst precursor S2-D was treated with water vapor containing dimethylamine (specifically, an aqueous solution containing 10% by weight of dimethylamine was contacted with S2-D at a temperature of 250°C for 10 h, and the mass hourly space velocity of the dimethylamine aqueous solution was 1 h⁻¹). -1 ), thus obtaining S2, a selective ring-opening catalyst for fused-ring aromatics.

[0201] The pore structure parameters of catalyst S2, determined by the low-temperature nitrogen adsorption method, are shown in Table 1.

[0202] 2. Catalyst Evaluation

[0203] Fixed-bed reactor volume: 50 ml;

[0204] Catalyst loading: 15 ml;

[0205] Raw materials: phenanthrene solution with toluene as solvent (phenanthrene mass fraction 25%);

[0206] Reaction temperature: 460℃;

[0207] Reaction pressure: 6.0 MPa;

[0208] Liquid hourly space velocity (LHSV) of phenanthrene solution: 1.0 h⁻¹ -1 ;

[0209] The volume ratio of hydrogen to phenanthrene is 4000:1.

[0210] In a fixed-bed reactor, a phenanthrene solution and hydrogen gas are contacted with the prepared polycyclic aromatic hydrocarbon selective ring-opening catalyst S2. The resulting reaction product is cooled by an air condenser and separated by a gas-liquid separator to obtain a liquid product. Samples of the liquid product are taken for analysis every 12 hours.

[0211] After 96 hours of reaction, the conversion rate of phenanthrene was calculated to be 95.1%, and the selectivity for light aromatic hydrocarbons (benzene, toluene, xylene, ethylbenzene) was 55.3%.

[0212] 3. Determination of catalyst carbon capacity index

[0213] After 528 hours of reaction, the conversion rate of the S2 catalyst decreased to 30% of the initial conversion rate of the fresh catalyst. Thermal analysis results showed that the carbon tolerance index of the S2 catalyst was 30.1%.

[0214] Example 3

[0215] 1. Catalyst Preparation

[0216] (1) Sodium-type β-zeolite raw powder (SiO2 / Al2O3 molar ratio of 55) was completely contacted with 4 mol / L glycolic acid solution and treated at 70℃ for 4 hours. Then, solid-liquid separation was performed, and the resulting filter cake was dried at 140℃ for 12 hours to obtain acid-treated β-zeolite molecular sieve S3-A.

[0217] (2) S3-A was exchanged twice with an ammonium salt aqueous solution (ammonium nitrate, ammonium salt concentration of 0.5 mol / L) (each exchange was at a temperature of 90℃ and a time of 6 h; after the first exchange, solid-liquid separation was performed, and the filter cake was dried at 120℃ for 3 hours, and then the same ammonium salt aqueous solution was used for the second exchange). The liquid-solid weight ratio was 4:1. After solid-liquid separation, the filter cake was dried at 120℃ for 3 hours to obtain ammonium type β zeolite molecular sieve S3-B.

[0218] (3) Mix 100 parts by weight of ammonium type β zeolite molecular sieve S3-B, 25 parts by weight of alumina binder and 15 parts by weight of extrusion molding aid dextrin, knead thoroughly and evenly, then add ammonium heptamolybdate solution containing 18 parts by weight of Mo and lanthanum nitrate solution containing 6 parts by weight of La respectively, mix evenly and then extrude and mold, dry at 120°C for 6 hours, and calcine at 550°C in air atmosphere for 6 hours to obtain catalyst precursor S3-C.

[0219] (4) The catalyst precursor S3-C was treated with ammonia-containing steam (specifically, an aqueous solution containing 20% ​​by weight of ammonia was contacted with S3-C at a temperature of 500°C for 2 hours, and the mass hourly space velocity of the ammonia solution was 6 h⁻¹). -1 ), thus obtaining catalyst precursor S3-D.

[0220] (5) The molecular sieve catalyst precursor S3-D was treated with water vapor containing trimethylamine (specifically, an aqueous solution containing 50% by weight of trimethylamine was contacted with S3-D at a temperature of 350°C for 4 hours, and the mass hourly space velocity of the trimethylamine aqueous solution was 2 h⁻¹). -1 ), thus obtaining S3, a selective ring-opening catalyst for fused-ring aromatics.

[0221] The pore structure parameters of catalyst S3, determined by the low-temperature nitrogen adsorption method, are shown in Table 1.

[0222] 2. Catalyst Evaluation

[0223] Fixed-bed reactor volume: 50 ml;

[0224] Catalyst loading: 15 ml;

[0225] Raw materials (by mass fraction): non-aromatic hydrocarbons 0.7%, toluene 11.9%, tetramethylbenzene isomers 29.8%, polycyclic aromatic hydrocarbons 57.6% (of which naphthalene accounts for 11.8%, C11) + Polycyclic aromatic hydrocarbons account for 88.2%;

[0226] Reaction temperature: 480℃;

[0227] Reaction pressure: 1.5 MPa;

[0228] Liquid hourly space velocity (LHSV) of the feedstock: 1.5 h⁻¹ -1 ;

[0229] Hydrogen to feedstock volume ratio: 2000:1.

[0230] In a fixed-bed reactor, the feedstock and hydrogen are contacted with the prepared polycyclic aromatic hydrocarbon selective ring-opening catalyst S3. The resulting reaction product is cooled by an air condenser and separated by a gas-liquid separator to obtain a liquid product. Samples of the liquid product are taken for analysis every 12 hours.

[0231] After 96 hours of reaction, the conversion rate of polycyclic aromatic hydrocarbons was calculated to be 79.1%, and the selectivity of light aromatic hydrocarbons (benzene, toluene, xylene, ethylbenzene) was 57.6%.

[0232] 3. Determination of catalyst carbon capacity index

[0233] After 960 hours of reaction, the conversion rate of the S3 catalyst decreased to 30% of the initial conversion rate of the fresh catalyst. Thermal analysis results showed that the carbon tolerance index of the S3 catalyst was 42.98%. Figure 1 .

[0234] Example 4

[0235] 1. Catalyst Preparation

[0236] (1) Sodium-type β-zeolite powder (SiO2 / Al2O3 molar ratio of 20) was completely contacted with 2 mol / L citric acid solution and treated at 80℃ for 4 hours. Then, solid-liquid separation was performed, and the resulting filter cake was dried at 120℃ for 3 hours.

[0237] The dried filter cake was subjected to a second acid treatment, which involved complete contact with a 2 mol / L citric acid solution and treatment at 80°C for 4 hours. Solid-liquid separation was then performed, and the resulting filter cake was dried at 120°C for 3 hours to obtain acid-treated β-zeolite molecular sieve S1-A.

[0238] (2) S1-A was exchanged twice with an ammonium salt aqueous solution (ammonium nitrate, ammonium salt concentration of 1 mol / L) (each exchange was at 85℃ for 3 hours; after the first exchange, solid-liquid separation was performed, and the filter cake was dried at 120℃ for 3 hours, and then the same ammonium salt aqueous solution was used for the second exchange). The liquid-solid weight ratio was 5:1. After solid-liquid separation, the filter cake was dried at 120℃ for 3 hours to obtain ammonium type β zeolite molecular sieve S1-B.

[0239] (3) Mix 100 parts by weight of ammonium type β zeolite molecular sieve S1-B, 40 parts by weight of alumina binder and 15 parts by weight of extrusion molding aid guar powder. After mixing thoroughly, add 15 parts by weight of ammonium heptamolybdate solution containing Mo and 20 parts by weight of lanthanum nitrate solution containing La respectively. After mixing thoroughly, extrude into strips, dry at 120°C for 3 hours, and calcine at 550°C in air atmosphere for 4 hours to obtain catalyst precursor S1-C.

[0240] (4) The catalyst precursor S1-C was treated with ethylamine-containing water vapor (specifically, an aqueous solution containing 18% by weight of ethylamine was contacted with S1-D at a temperature of 450°C for 4 hours, and the mass hourly space velocity of the ethylamine aqueous solution was 4 h⁻¹). -1 ), thus obtaining S4, a selective ring-opening catalyst for fused-ring aromatics.

[0241] The pore structure parameters of catalyst S4, determined by the low-temperature nitrogen adsorption method, are shown in Table 1.

[0242] 2. Catalyst Evaluation

[0243] Fixed-bed reactor volume: 50 ml;

[0244] Catalyst loading: 15 ml;

[0245] Raw material: Tetrahydronaphthalene (a selectively saturated product obtained by selective hydrogenation of naphthalene);

[0246] Reaction temperature: 380℃;

[0247] Reaction pressure: 4.0 MPa;

[0248] Liquid hourly space velocity (LHSV) of tetrahydronaphthalene: 4.0 h⁻¹ -1 ;

[0249] The volume ratio of hydrogen to tetrahydronaphthalene is 1000:1.

[0250] In a fixed-bed reactor, tetrahydronaphthalene and hydrogen were contacted with the prepared polycyclic aromatic hydrocarbon selective ring-opening catalyst S4. The resulting reaction product was cooled by an air condenser and separated by a gas-liquid separator to obtain a liquid product. Samples of the liquid product were taken for analysis every 12 hours.

[0251] After 96 hours of reaction, the conversion rate of tetrahydronaphthalene was calculated to be 82.3%, and the selectivity for light aromatic hydrocarbons (benzene, toluene, xylene, ethylbenzene) was 59.6%.

[0252] 3. Determination of catalyst carbon capacity index

[0253] After 828 hours of reaction, the conversion rate of the S4 catalyst decreased to 30% of the initial conversion rate of the fresh catalyst. Thermal analysis results showed that the carbon tolerance index of the S4 catalyst was 33.2%.

[0254] Example 5

[0255] 1. Catalyst Preparation

[0256] (1) Sodium-type β-zeolite raw powder (SiO2 / Al2O3 molar ratio of 55) was completely contacted with 1 mol / L oxalic acid solution and treated at 60℃ for 8 hours. Then, solid-liquid separation was performed, and the resulting filter cake was dried at 110℃ for 12 hours to obtain acid-treated β-zeolite molecular sieve S5-A.

[0257] (2) S5-A was exchanged twice with an ammonium salt aqueous solution (ammonium nitrate, ammonium salt concentration of 0.5 mol / L) (each exchange was at 90℃ for 6 hours; after the first exchange, solid-liquid separation was performed, and the filter cake was dried at 120℃ for 3 hours, and then the same ammonium salt aqueous solution was used for the second exchange). The liquid-solid weight ratio was 8:1. After solid-liquid separation, the filter cake was dried at 110℃ for 10 hours to obtain ammonium type β zeolite molecular sieve S5-B.

[0258] (3) Mix 100 parts by weight of ammonium type β zeolite molecular sieve S5-B, 60 parts by weight of alumina binder and 20 parts by weight of extrusion molding aid guar powder, knead thoroughly and evenly, then add 30 parts by weight of niobium oxalate solution, mix evenly and then extrude and mold, dry at 120°C for 6 hours, and calcine at 550°C for 6 hours in air atmosphere to obtain catalyst precursor S5-C.

[0259] (4) The catalyst precursor S5-C was treated with ammonia-containing steam (specifically, an aqueous solution containing 10% by weight of ammonia was contacted with S5-C at a temperature of 350°C for 4 hours, and the mass hourly space velocity of the ammonia solution was 1 h⁻¹). -1 ), thus obtaining catalyst precursor S5-D.

[0260] (5) The molecular sieve catalyst precursor S5-D was treated with water vapor containing methylamine (specifically, an aqueous solution containing 20% ​​by weight of methylamine was contacted with S5-D at a temperature of 400°C for 4 hours, and the mass hourly space velocity of the trimethylamine aqueous solution was 6 h⁻¹). -1 ), thus obtaining S5, a selective ring-opening catalyst for polycyclic aromatic hydrocarbons.

[0261] The pore structure parameters of catalyst S5, determined by the low-temperature nitrogen adsorption method, are shown in Table 1.

[0262] 2. Catalyst Evaluation

[0263] Fixed-bed reactor volume: 50 ml;

[0264] Catalyst loading: 15 ml;

[0265] Raw material: Tetrahydronaphthalene (a selectively saturated product obtained by selective hydrogenation of naphthalene);

[0266] Reaction temperature: 400℃;

[0267] Reaction pressure: 4.0 MPa;

[0268] Liquid hourly space velocity (LHSV) of tetrahydronaphthalene: 2.0 h⁻¹ -1 ;

[0269] The volume ratio of hydrogen to tetrahydronaphthalene is 2000:1.

[0270] In a fixed-bed reactor, tetrahydronaphthalene and hydrogen were contacted with the prepared polycyclic aromatic hydrocarbon selective ring-opening catalyst S5. The resulting reaction product was cooled by an air condenser and separated by a gas-liquid separator to obtain a liquid product. Samples of the liquid product were taken for analysis every 12 hours.

[0271] After 96 hours of reaction, the conversion rate of tetrahydronaphthalene was calculated to be 82.3%, and the selectivity for light aromatic hydrocarbons (benzene, toluene, xylene, ethylbenzene) was 59.6%.

[0272] 3. Determination of catalyst carbon capacity index

[0273] After 912 hours of reaction, the conversion rate of the S5 catalyst decreased to 30% of the initial conversion rate of the fresh catalyst. Thermal analysis results showed that the carbon tolerance index of the S5 catalyst was 29.8%.

[0274] Example 6

[0275] 1. Catalyst Preparation

[0276] (1) Sodium-type β-zeolite raw powder (SiO2 / Al2O3 molar ratio of 55) was completely contacted with 2 mol / L acetic acid solution and treated at 80℃ for 4 hours. Then, solid-liquid separation was performed, and the resulting filter cake was dried at 120℃ for 2 hours. The acid treatment was repeated once under the same conditions to obtain acid-treated β-zeolite molecular sieve S6-A.

[0277] (2) S6-A was exchanged twice with an ammonium salt aqueous solution (ammonium nitrate, ammonium salt concentration of 0.5 mol / L) (each exchange was at 90℃ for 6 hours; after the first exchange, solid-liquid separation was performed, and the filter cake was dried at 120℃ for 3 hours, and then the same ammonium salt aqueous solution was used for the second exchange). The liquid-solid weight ratio was 8:1. After solid-liquid separation, the filter cake was dried at 120℃ for 4 hours to obtain ammonium type β zeolite molecular sieve S6-B.

[0278] (3) Mix 100 parts by weight of ammonium type β zeolite molecular sieve S6-B, 100 parts by weight of alumina binder and 20 parts by weight of extrusion molding aid guar powder, knead thoroughly and evenly, extrude and mold, dry at 120°C for 6 hours, and calcine at 550°C in air atmosphere for 6 hours to obtain catalyst precursor S6-C.

[0279] (4) The catalyst precursor S6-C was treated with ammonia-containing steam (specifically, an aqueous solution containing 10% by weight of ammonia was contacted with S6-C at a temperature of 500°C for 2 hours, and the mass hourly space velocity of the ammonia solution was 1 h⁻¹). -1 ), thus obtaining catalyst precursor S6-D.

[0280] (5) The molecular sieve catalyst precursor S6-D was treated with water vapor containing ethylamine (specifically, an aqueous solution containing 18% by weight of ethylamine was contacted with S6-D at a temperature of 450°C for 2 hours, and the mass hourly space velocity of the trimethylamine aqueous solution was 1 h⁻¹). -1 ), catalyst precursor S6-E.

[0281] (6) The catalyst precursor S6-E was impregnated in an equal volume of ammonium tetramolybdate solution containing 30 parts by weight of Mo at room temperature for 4 hours, then dried at 120°C for 4 hours, and calcined at 550°C in air for 4 hours to obtain the selective ring-opening catalyst S6 for polycyclic aromatic hydrocarbons.

[0282] The pore structure parameters of catalyst S6, determined by the low-temperature nitrogen adsorption method, are shown in Table 1.

[0283] 2. Catalyst Evaluation

[0284] Fixed-bed reactor volume: 50 ml;

[0285] Catalyst loading: 15 ml;

[0286] Raw material: Tetrahydronaphthalene (a selectively saturated product obtained by selective hydrogenation of naphthalene);

[0287] Reaction temperature: 400℃;

[0288] Reaction pressure: 4.0 MPa;

[0289] Liquid hourly space velocity (LHSV) of tetrahydronaphthalene: 2.0 h⁻¹ -1 ;

[0290] The volume ratio of hydrogen to tetrahydronaphthalene is 2000:1.

[0291] In a fixed-bed reactor, tetrahydronaphthalene and hydrogen were contacted with the prepared polycyclic aromatic hydrocarbon selective ring-opening catalyst S6. The resulting reaction product was cooled by an air condenser and separated by a gas-liquid separator to obtain a liquid product. Samples of the liquid product were taken for analysis every 12 hours.

[0292] After 96 hours of reaction, the conversion rate of tetrahydronaphthalene was calculated to be 66.8%, and the selectivity for light aromatic hydrocarbons (benzene, toluene, xylene, ethylbenzene) was 49.7%.

[0293] 3. Determination of catalyst carbon capacity index

[0294] After 876 hours of reaction, the conversion rate of the S6 catalyst decreased to 30% of the initial conversion rate of the fresh catalyst. Thermal analysis results showed that the carbon tolerance index of the S6 catalyst was 26.9%.

[0295] Example 7

[0296] 1. Catalyst Preparation

[0297] (1) Sodium-type β-zeolite raw powder (SiO2 / Al2O3 molar ratio of 55) was completely contacted with 4 mol / L glycolic acid solution and treated at 70℃ for 4 hours. Then, solid-liquid separation was performed, and the resulting filter cake was dried at 140℃ for 12 hours to obtain acid-treated β-zeolite molecular sieve S7-A.

[0298] (2) S7-A was exchanged twice with an ammonium salt aqueous solution (ammonium nitrate, ammonium salt concentration of 0.5 mol / L) (each exchange was at 90℃ for 6 hours; after the first exchange, solid-liquid separation was performed, and the filter cake was dried at 120℃ for 3 hours, and then the same ammonium salt aqueous solution was used for the second exchange). The liquid-solid weight ratio was 4:1. After solid-liquid separation, the filter cake was dried at 120℃ for 3 hours to obtain ammonium type β zeolite molecular sieve S7-B.

[0299] (3) Mix 100 parts by weight of ammonium type β zeolite molecular sieve S7-B, 25 parts by weight of alumina binder and 15 parts by weight of extrusion molding aid guar powder, knead thoroughly and evenly, then add 20 parts by weight of niobium oxalate solution, 20 parts by weight of ammonium heptamolybdate solution, and 10 parts by weight of lanthanum nitrate solution, respectively. After mixing evenly, extrude and mold, dry at 120°C for 6 hours, and calcine at 550°C for 6 hours in air atmosphere to obtain catalyst precursor S7-C.

[0300] (4) The catalyst precursor S7-C was treated with ammonia-containing steam (specifically, an aqueous solution containing 20% ​​by weight of ammonia was contacted with S7-C at a temperature of 500°C for 2 hours, and the mass hourly space velocity of the ammonia solution was 6 h⁻¹). -1 ), thus obtaining catalyst precursor S7-D.

[0301] (5) The molecular sieve catalyst precursor S7-D was treated with water vapor containing methylamine (specifically, an aqueous solution containing 20% ​​by weight of methylamine was contacted with S7-D at a temperature of 350°C for 4 hours, and the mass hourly space velocity of the methylamine aqueous solution was 2 h⁻¹). -1 ), thus obtaining S7, a selective ring-opening catalyst for fused-ring aromatics.

[0302] The pore structure parameters of catalyst S7, determined by the low-temperature nitrogen adsorption method, are shown in Table 1.

[0303] 2. Catalyst Evaluation

[0304] Fixed-bed reactor volume: 50 ml;

[0305] Catalyst loading: 15 ml;

[0306] Raw materials (by mass fraction): toluene 0.1%, xylene 0.2%, trimethylbenzene isomer 9.0%, tetramethylbenzene isomer 26.8%, indene 1.6%, polycyclic aromatic hydrocarbons 62.3% (of which naphthalene accounts for 71.6%, C11) + Polycyclic aromatic hydrocarbons accounted for 28.4%;

[0307] Reaction temperature: 420℃;

[0308] Reaction pressure: 3.0 MPa;

[0309] Liquid hourly space velocity (LHSV) of the feedstock: 2.5 h⁻¹ -1 ;

[0310] Hydrogen to feedstock volume ratio: 2000:1.

[0311] In a fixed-bed reactor, the feedstock and hydrogen are contacted with the prepared polycyclic aromatic hydrocarbon selective ring-opening catalyst S7. The resulting reaction product is cooled by an air condenser and separated by a gas-liquid separator to obtain a liquid product. Samples of the liquid product are taken for analysis every 12 hours.

[0312] After 96 hours of reaction, the conversion rate of polycyclic aromatic hydrocarbons was calculated to be 63.0%, and the selectivity of light aromatic hydrocarbons (benzene, toluene, xylene, ethylbenzene) was 77.0%.

[0313] 3. Determination of catalyst carbon capacity index

[0314] After 2016 hours of reaction, the conversion rate of the S7 catalyst decreased to 30% of the initial conversion rate of the fresh catalyst. Thermal analysis results showed that the carbon tolerance index of the S7 catalyst was 37.8%.

[0315] Table 1

[0316]

[0317]

[0318] Through Table 1 and Figure 1 The results show that the selective ring-opening catalyst for polycyclic aromatic hydrocarbons prepared by the method of the present invention has a specific mesoporous structure, a high carbon capacity index, and exhibits excellent stability and a long lifespan in the reaction of polycyclic aromatic hydrocarbons to prepare light aromatic hydrocarbons. In contrast, the catalysts prepared by the comparative method show significantly lower performance than those of the embodiments of the present invention, exhibiting poorer stability and a shorter lifespan.

[0319] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing light aromatics from polycyclic aromatic hydrocarbons, the method comprising: Under the reaction conditions for the selective ring-opening of polycyclic aromatic hydrocarbons to prepare light aromatic hydrocarbons, polycyclic aromatic hydrocarbons and / or selectively saturated products of polycyclic aromatic hydrocarbons are contacted with a catalyst. The catalyst comprises β-zeolite, a binder, and a metallic active component. Relative to 100 parts by weight of β-zeolite, the binder content is 15-300 parts by weight, the metallic active component content is 0.1-160 parts by weight, and the catalyst has a mesoporous specific surface area of ​​40-500 m². 2 / g, mesopore volume accounts for 30-95% of the total pore volume, and the mesopore volume is 0.1-0.6cm. 3 / g; The binder is selected from at least one of alumina, silica, boehmite and titanium dioxide; The active metal component is selected from Group VB elements and / or Group VIB elements and rare earth elements; The catalyst preparation method includes the following steps: (1) The β-zeolite raw powder with a silica / alumina molar ratio of 12-350 is subjected to acid treatment at least once; (2) Ammonium exchange was performed on the molecular sieve obtained by acid treatment to obtain ammonium-type β-zeolite; (3) The ammonium-type β-zeolite and the binder are molded to obtain the catalyst precursor; (4) Treat the catalyst precursor with water vapor containing organic amines; The method further includes: introducing a metal active component in step (3), and / or introducing a metal active component after the treatment in step (4).

2. The method according to claim 1, wherein, The binder content is 20-150 parts by weight relative to 100 parts by weight of β-zeolite, and the content of the metal active component is 20-120 parts by weight.

3. The method according to claim 1, wherein, The Group VB elements are selected from vanadium and / or niobium.

4. The method according to claim 1, wherein, The group VIB elements are selected from molybdenum and / or tungsten.

5. The method according to claim 1, wherein, The rare earth element is selected from lanthanum and / or cerium.

6. The method according to claim 1, wherein, The content of the Group VB element is 0.1-80 parts by weight relative to 100 parts by weight of β zeolite; And / or, relative to 100 parts by weight of β zeolite, the content of the group VIB element is 0.1-80 parts by weight; And / or, relative to 100 parts by weight of β-zeolite, the content of the rare earth element is 0.1-80 parts by weight.

7. The method according to claim 6, wherein, The content of the Group VB element is 15-60 parts by weight relative to 100 parts by weight of β zeolite; And / or, relative to 100 parts by weight of β zeolite, the content of the group VIB element is 15-60 parts by weight.

8. The method according to claim 6, wherein, The rare earth element content is 5-20 parts by weight relative to 100 parts by weight of β zeolite.

9. The method according to any one of claims 1-8, wherein, The catalyst has a mesoporous specific surface area of ​​40-400 m². 2 / g, mesopore volume accounts for 30-90% of the total pore volume.

10. The method according to any one of claims 1-8, wherein, The silica / alumina molar ratio of the β-zeolite raw powder is 15-250.

11. The method according to any one of claims 1-8, wherein, In step (1), the β-zeolite powder is acid-treated at least once with organic acid.

12. The method according to claim 11, wherein, The acid treatment in step (1) includes contacting β-zeolite with an acid solution.

13. The method according to claim 12, wherein, The acid treatment is performed 1-4 times.

14. The method according to claim 13, wherein, The acid treatment is performed 1-2 times.

15. The method according to claim 11, wherein, The organic acid is selected from at least one of citric acid, acetic acid, glycolic acid, oxalic acid, and ethylenediaminetetraacetic acid.

16. The method according to claim 12, wherein, The concentration of the acid solution is 0.2-4.5 mol / L.

17. The method according to any one of claims 1-8, wherein, The acid treatment conditions include: a temperature of 50-90℃ and a time of 2-15h.

18. The method according to any one of claims 1-8, wherein, The molding process involves mixing ammonium-type β-zeolite, a binder, and optionally an extrusion molding aid, followed by extrusion molding, drying, and calcination.

19. The method according to claim 18, wherein, The roasting conditions include a temperature of 200-600℃ and a time of 3-10h.

20. The method according to any one of claims 1-8, wherein, Step (4) involves treating the catalyst precursor with water vapor containing organic amines, which includes contacting the catalyst precursor with an aqueous solution containing organic amines under conditions that satisfy the vaporization of organic amines and water.

21. The method according to claim 20, wherein, The organic amine is selected from at least one of methylamine, ethylamine, dimethylamine, and trimethylamine.

22. The method according to claim 20, wherein, The aqueous solution containing organic amines has an organic amine content of 10-80% by weight.

23. The method according to claim 22, wherein, The organic amine in the aqueous solution contains 10-50% by weight.

24. The method of claim 20, wherein, The contact conditions include: a temperature of 100-600℃, a time of 2-12 h, and a mass hourly space velocity (MSV) of 1-15 h⁻¹ for the aqueous solution containing organic amines. -1 .

25. The method according to claim 24, wherein, The contact conditions include: a temperature of 200-500℃, a time of 4-10 h, and a mass hourly space velocity (MSV) of 1-8 h⁻¹ for the aqueous solution containing organic amines. -1 .

26. The method according to any one of claims 1-8, wherein, The metal active component introduced in step (3) includes: The ammonium-type β-zeolite, binder, and metal active component precursor are molded; and / or, The active metal component is introduced into the catalyst precursor by impregnation.

27. The method according to any one of claims 1-8, wherein, The introduction of the metal active component in step (4) includes: after the treatment, introducing the metal active component into the product obtained by impregnation.

28. The method according to any one of claims 1-8, wherein, The method further includes treating the catalyst precursor with ammonia-containing steam before treating the catalyst precursor with water vapor containing organic amine in step (4).

29. The method according to claim 28, wherein, The process of treating the catalyst precursor with ammonia-containing water vapor includes contacting the catalyst precursor with ammonia water under conditions that satisfy ammonia and water vaporization.

30. The method according to claim 29, wherein, The ammonia water contains 5-25% ammonia by weight.

31. The method according to claim 30, wherein, The ammonia water contains 10-20% ammonia by weight.

32. The method according to claim 29, wherein, The contact conditions include: a temperature of 200-600℃; a time of 1-12 hours; and a mass hourly space velocity (MSV) of 0.5-10 h⁻¹ for the ammonia solution. -1 .

33. The method according to claim 32, wherein, The contact conditions include: a temperature of 250-550℃; a time of 2-10 hours; and a mass hourly space velocity (MSV) of 1-6 h⁻¹ for the ammonia solution. -1 .

34. The method according to any one of claims 1-8, wherein, The polycyclic aromatic hydrocarbon has 10-20 carbon atoms.

35. The method according to claim 34, wherein, The polycyclic aromatic hydrocarbon is selected from at least one of naphthalene, methylnaphthalene, fluorene, phenanthrene, anthracene, and pyrene.

36. The method according to any one of claims 1-8, wherein, The reaction conditions for the selective ring-opening preparation of light aromatics from polycyclic aromatic hydrocarbons include: a temperature of 300-500℃, a pressure of 0.1-8 MPa, and a mass hourly space velocity (HSV) of 1-10 h⁻¹. -1 .

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