Heavy aromatics lightening and transalkylation process

Abstract

The present application relates to the technical field of molecular sieve catalysts, and particularly relates to a heavy aromatic lightening and transalkylation method. A heavy aromatic lightening and transalkylation method, the method comprising: contacting heavy aromatics and optionally benzene and / or toluene with a catalyst under heavy aromatic lightening and transalkylation reaction conditions; the catalyst being a modified twelve-membered ring silicon-aluminum molecular sieve, the modified twelve-membered ring silicon-aluminum molecular sieve having a silica / alumina molar ratio of 6-100, a mesopore specific surface area of 30-300 m 2 / g, and a mesopore volume accounting for 20-95% of the total pore volume. The method has the advantages of excellent aromatic conversion, high selectivity and stability of target products (such as xylene) in the heavy aromatic lightening and transalkylation reaction, and can be used for industrial production of heavy aromatic lightening and transalkylation.

Description

Technical Field

[0001] This invention relates to the technical field of molecular sieve catalysts, specifically to a method for the lightening and alkylation of heavy aromatics. Background Technology

[0002] Xylene is an important basic organic raw material, widely used in pharmaceuticals, resins, and oils. Xylene has three isomers: o-xylene (OX), p-xylene (PX), and m-xylene (MX). PX has the largest market demand, mainly used in the production of terephthalic acid (PTA) and dimethyl terephthalate (PMT), which in turn produce polyethylene terephthalate (PET). Current methods for producing p-xylene involve separating PX from a mixture of isomers with similar boiling points from a thermodynamically equilibrium mixture of xylenes generated by naphtha catalytic reforming using adsorption or crystallization techniques. The remaining OX and MX are then further isomerized, and the resulting mixed xylenes are used as feedstock for PX separation. To increase PX production, methods such as toluene disproportionation and the reaction of toluene with heavy aromatics (C9) are employed. + A) Alkyl transfer, benzene and heavy aromatics (C9) + A) Alkyl transfer reaction to generate mixed xylenes is an effective process route for increasing PX production.

[0003] The three reactions mentioned above that increase xylene production are typical Acid-catalyzed reactions commonly use acidic zeolite molecular sieves or metal-modified acidic zeolite molecular sieves as catalysts. Among currently industrialized catalysts, the toluene disproportionation reaction utilizes the methyl transfer reaction between two toluene molecular sieves to produce xylene and benzene. Mordenite zeolite and / or ZSM-5 molecular sieves are commonly used. Because no heavy aromatics are introduced into the reaction system, the molecular sieve diffusion rate is high, the catalyst's empty space velocity is relatively high, and the catalyst stability is good. Benzene and heavy aromatics (C9...) + A) Alkyl transfer reaction, toluene and heavy aromatics (C9) + A) Alkyl transfer reactions mostly utilize mordenite and β-zeolite catalysts. This is primarily because the introduction of heavy aromatics into the reaction system necessitates molecular sieves with larger pore sizes to facilitate diffusion and mitigate catalyst deactivation due to coking. Toluene / benzene and heavy aromatic alkyl transfer technologies can effectively increase xylene production and yield, while also enabling C9 alkyl transfer reactions. + Effective conversion of C9 is currently the most widely used xylene production enhancement technology. With the increasing depth of petroleum refining, the growing heavier weight of upstream reforming feedstocks, and the increasingly stringent standards for clean oil products, C9 production is expected to increase. + With the significant increase in heavy aromatics, especially low-quality heavy aromatics, it is particularly important to convert them into light aromatics such as xylene through heavy aromatics lightening and alkyl transfer.

[0004] Patent application CN 1472181A (China Petroleum & Chemical Corporation, Catalyst and Preparation Method for Lightening Heavy Aromatics, 2002.07.30) describes the preparation of a catalyst using ZSM-5 molecular sieve, mordenite, and alumina as a composite support, and loading Group VIII metals and rhenium or tin. (C9) + The conversion rate of aromatic hydrocarbons can reach up to 41.9%.

[0005] Patent application CN 101987969A (China Petroleum & Chemical Corporation, Research Institute of Petroleum Processing, a method for using C9...) + A method for converting heavy aromatics into light aromatics (July 30, 2009) employs C9... + A method involving a primary reaction of heavy aromatics with an iridium-containing catalyst at 450-500℃ in the presence of hydrogen, followed by a secondary reaction of the product with a zeolite-containing catalyst at 380-420℃ in the presence of hydrogen, is used to carry out the C9... + Heavy aromatics are converted into light aromatics. The iridium-containing catalyst comprises a high-temperature resistant inorganic oxide support and 0.01-2.0% by mass of iridium and 0.01-3.0% by mass of halogen, calculated based on the support. The zeolite-containing catalyst comprises a zeolite-containing support and 0.01-2.0% by mass of platinum group metals, calculated based on the support. The zeolite is selected from ZSM-5, mordenite, β-zeolite, or mixtures thereof.

[0006] Patent application CN102744098A (China Petroleum & Chemical Corporation, Catalyst for increasing the production of BTX aromatics and trimethylbenzene by hydrocracking of heavy aromatics, 2011.04.20) uses hydrogen-form binder-free ten-membered ring zeolite supported on platinum or palladium as a catalyst, which can effectively remove the ethyl, propyl and butyl groups of heavy aromatics such as methyl ethylbenzene, propylbenzene and butylbenzene to obtain benzene and toluene.

[0007] Patent application CN 101811063A (China Petroleum & Chemical Corporation, Catalyst for Lightening and Alkyl Transfer of C9 and Above Heavy Aromatics, 2009.02.19) describes the preparation of a catalyst using hydrogen-form nano-zeolite (selected from at least one of β-zeolite, mordenite, and ZSM-5) as the active component and group VIB elements as modifying agents. + The conversion rate of aromatic hydrocarbons can reach up to 55.2%.

[0008] Patent application CN 110075912A (Nanjing University of Technology, a type of C) 10 +A catalyst for preparing low-carbon aromatic hydrocarbons by heavy aromatic hydrocarbon hydrodealkylation and a preparation method thereof, 2019.05.20) uses a composite molecular sieve such as mordenite, beta molecular sieve, ZSM-5 molecular sieve, and Y molecular sieve as a carrier, uses one or more of transition metal oxides such as MoO3 and NiO, Bi2O3, Co3O4, or CuO and rare earth oxides as an active component, C 10 + The conversion rate of heavy aromatic hydrocarbons is as high as 42.4%.

[0009] The introduction of hydrogenation metals, especially the use of noble metals, can improve the C 10 + heavy aromatic hydrocarbon processing capacity and stability, but also causes aromatic ring saturation hydrogenation, increases the loss rate of aromatic ring, reduces the selectivity of the target product, and reduces the quality of benzene, and other adverse effects.

[0010] For molecular sieve catalysts, the most serious consequence of carbon deposition is that with the increase of reaction time, the acid sites of the catalyst are covered and the molecular sieve channels are blocked, resulting in a significant decrease in catalyst activity or even complete deactivation (Research Progress on Deactivation Characteristics of Methanol-to-Aromatic Hydrocarbon Catalysts, Industrial Catalysis, 2018, 26(11): 7). Especially for microporous molecular sieves, a small amount of carbon deposition can cause a significant decrease in catalyst activity. Generally, the carbon deposition amount of deactivated molecular sieve catalysts is highest at about 10%-15%.

[0011] At present, the heavy aromatic hydrocarbon lightening and transalkylation molecular sieve catalysts used at home and abroad are basically still limited to several types such as beta zeolite, mordenite, and ZSM-5. Due to the limitation of pore structure, the utilization rate of internal surface acid sites of ZSM-5 molecular sieve with ten-membered ring channels is low, and it is more prone to coking and deactivation than mordenite and beta zeolite with twelve-membered ring channels. Although the carbon capacity of mordenite and beta zeolite is slightly higher than that of ZSM-5 molecular sieve, they still have C 10 + heavy aromatic hydrocarbon processing capacity, and the catalyst life is significantly lower than that of the transalkylation catalyst. Therefore, improving the diffusion performance and carbon capacity of the catalyst is the key to solving the problem of insufficient catalyst stability. SUMMARY

[0012] The purpose of the present application is to overcome the problem of short catalyst life and poor stability caused by carbon deposition in the prior art, and to provide a heavy aromatic hydrocarbon lightening and transalkylation method. This method has excellent aromatic hydrocarbon conversion rate, high target product (such as xylene) selectivity and stability in heavy aromatic hydrocarbon lightening and transalkylation reactions, and can be used for industrial production of heavy aromatic hydrocarbon lightening and transalkylation.

[0013] To achieve the above object, the present application provides a heavy aromatics lightening and transalkylation method, which comprises: contacting heavy aromatics and optionally benzene and / or toluene with a catalyst under heavy aromatics lightening and transalkylation reaction conditions; the catalyst is a modified twelve-membered ring silicon-aluminum molecular sieve, the modified twelve-membered ring silicon-aluminum molecular sieve has a silica / alumina molar ratio of 6-100, a mesopore specific surface area of 30-300 m 2 / g, and a mesopore volume accounting for 20-95% of the total pore volume.

[0014] Preferably, the preparation method of the modified twelve-membered ring silicon-aluminum molecular sieve comprises the following steps:

[0015] (1) alkali treatment of a twelve-membered ring silicon-aluminum molecular sieve;

[0016] (2) ammonium exchange of the molecular sieve obtained by the alkali treatment to obtain an ammonium type molecular sieve;

[0017] (3) treatment of the ammonium type molecular sieve with water vapor containing an organic amine;

[0018] The method further comprises shaping before step (3) and / or after step (3).

[0019] The twelve-membered ring silicon-aluminum molecular sieve has a silica / alumina molar ratio of 9-200, preferably 10-150.

[0020] Preferably, the treatment of the ammonium type molecular sieve with water vapor containing an organic amine in step (3) comprises:

[0021] Under conditions meeting the vaporization of the organic amine and water, contacting an aqueous solution containing the organic amine with the ammonium type molecular sieve.

[0022] The inventors of the present application have found that, in the process of heavy aromatic hydrocarbon lightening and transalkylation, the modified twelve-membered ring silicon-aluminum molecular sieve is selected as the catalyst to complete the heavy aromatic hydrocarbon lightening and transalkylation reaction, which has the advantages of excellent aromatic hydrocarbon conversion rate, high selectivity of target product (such as dimethylbenzene) and high stability, and can be used in the industrial production of heavy aromatic hydrocarbon lightening and transalkylation, and is worthy of large-scale promotion. In the preparation process of the modified molecular sieve catalyst, the ammonium type molecular sieve is treated with steam containing organic amine, which is beneficial to the pore expansion of the molecular sieve and the formation of a specific mesoporous structure, so that the obtained molecular sieve catalyst is rich in mesopores, which is beneficial to the diffusion of heavy aromatic hydrocarbon molecules and improves the carbon capacity of the molecular sieve. The modified molecular sieve catalyst has a specific mesoporous structure and a specific silicon-aluminum ratio, so that the carbon capacity is strong, the catalyst service life is long, and the stability is good. The preparation method of the modified molecular sieve can prepare a molecular sieve catalyst with high carbon capacity index, the catalyst has a long service life and good stability, and the heavy aromatic hydrocarbon lightening and transalkylation are smoothly completed, and the conversion rate of heavy aromatic hydrocarbon is improved. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Thermogravimetric analysis curve of the molecular sieve catalyst prepared in Example 1 after 980 hours of reaction. DETAILED DESCRIPTION

[0024] The endpoints of the ranges and any values claimed herein are not to be understood as being limited to the exact values recited as implicitly disclosed by the above description. Ranges can be expressed as from one value and / or to another value. When such a range is expressed, the endpoints are included in the range. When, in this specification, a range or a parameter is given, it will be understood that any other given range or other parameter, that can be within the field of the disclosure, is also contemplated unless the context clearly indicates otherwise. The disclosure is not limited to the exemplary parameters given herein; any other given range or other parameter, that can be within the field of the disclosure, is contemplated unless the context clearly indicates otherwise.

[0025] The present application provides a heavy aromatic hydrocarbon lightening and transalkylation method, which comprises: contacting heavy aromatic hydrocarbon and optionally benzene and / or toluene with a catalyst under heavy aromatic hydrocarbon lightening and transalkylation reaction conditions; the catalyst is a modified twelve-membered ring silicon-aluminum molecular sieve, the silicon oxide / aluminum oxide molar ratio of the modified twelve-membered ring silicon-aluminum molecular sieve is 6-100, the mesopore specific surface area is 30-300 m 2 / g, and the mesopore volume accounts for 20-95% of the total pore volume.

[0026] In the present application, in the process of heavy aromatic hydrocarbon lightening and transalkylation, the reaction raw material can contain components such as benzene and toluene in addition to heavy aromatic hydrocarbon.

[0027] In the present application, the mesopore specific surface area, mesopore volume and total pore volume are determined by low-temperature nitrogen adsorption. The specific testing method is as follows: nitrogen adsorption experiment is carried out at 77K liquid nitrogen temperature by using a physical adsorption instrument in the range of relative pressure of 10 -3 -1, and an adsorption isotherm is obtained. Based on the desorption branch of the adsorption isotherm, the mesopore distribution of the sample is analyzed by using BJH independent cylinder model; the mesopore volume and micropore volume are measured by using t-curve method. The mesopore specific surface area is obtained by linear regression of BET model.

[0028] In a specific preferred embodiment, the silica / alumina molar ratio of the modified twelve-membered ring silicon-aluminum molecular sieve is 8-80.

[0029] Preferably, the mesopore specific surface area of the modified twelve-membered ring silicon-aluminum molecular sieve is 50-250m 2 / g. Specifically, it can be as follows: 70m 2 / g, 90m 2 / g, 110m 2 / g, 130m 2 / g, 150m 2 / g, 170m 2 / g, 190m 2 / g, 210m 2 / g, 230m 2 / g, or a range between any two of them.

[0030] Preferably, the mesopore volume of the modified twelve-membered ring silicon-aluminum molecular sieve is 0.1-0.5cm 3 / g, and more preferably 0.2-0.4cm 3 / g.

[0031] Preferably, the mesopore volume of the modified twelve-membered ring silicon-aluminum molecular sieve accounts for 25-90% of the total pore volume, and further preferably 30-75%.

[0032] According to the present application, the modified twelve-membered ring silicon-aluminum molecular sieve catalyst is applied to the heavy aromatic lightening and transalkylation method provided by the present application. After the reaction, the molecular sieve catalyst has a relatively high carbon capacity index. Preferably, the carbon capacity index of the molecular sieve catalyst determined by thermal analysis method is not less than 15%, and more preferably 25%-45%. The carbon capacity index of the catalyst in the prior art is usually less than 10%.

[0033] In the present application, the carbon deposition index refers to the ratio of the carbon deposition amount of the catalyst to the mass of the catalyst after reaction, multiplied by 100%, when the conversion rate of the reaction raw material (for example, heavy aromatic hydrocarbon) is 30% of the initial conversion rate of the fresh catalyst, which is determined by a thermal analysis method. The carbon deposition amount of the catalyst is tested on a TA SDTQ600 comprehensive thermal analyzer of the United States TA Company, and the testing method is as follows: under an air atmosphere, the temperature is raised from room temperature to 1073K at a temperature raising rate of 10K·min -1 The weight loss amount of the catalyst in the range of 473K-1073K is the carbon deposition amount.

[0034] According to the present application, the type of the modified twelve-membered ring silicon-aluminum molecular sieve can be selected in a wide range, as long as the molar ratio of silicon oxide to aluminum oxide, the mesopore specific surface area and the mesopore volume can meet the above requirements. The person skilled in the art can make a conventional selection within a reasonable range according to conventional technical means. Preferably, the modified twelve-membered ring silicon-aluminum molecular sieve is mordenite and / or ZSM-12 molecular sieve, and further preferably is mordenite.

[0035] The method for lightening heavy aromatic hydrocarbon and transalkylation provided by the present application contacts heavy aromatic hydrocarbon and optionally benzene and / or toluene with a catalyst by selecting a specific catalyst and combining with specific process conditions, to complete the lightening and transalkylation of heavy aromatic hydrocarbon. The method is simple to operate and easy to implement, and has excellent aromatic hydrocarbon conversion rate and high selectivity and stability of target products (for example, xylene) during the lightening and transalkylation of heavy aromatic hydrocarbon. Moreover, the method is especially suitable for industrialized production of the lightening and transalkylation of heavy aromatic hydrocarbon, effectively improves the lightening and conversion of heavy aromatic hydrocarbon, and realizes large-scale industrialized production.

[0036] According to the present application, preferably, the preparation method of the modified twelve-membered ring silicon-aluminum molecular sieve comprises the following steps:

[0037] (1) alkali treatment of the twelve-membered ring silicon-aluminum molecular sieve;

[0038] (2) ammonium exchange of the molecular sieve obtained by alkali treatment to obtain an ammonium type molecular sieve;

[0039] (3) treatment of the ammonium type molecular sieve with steam containing an organic amine;

[0040] The method further comprises molding before step (3) and / or after step (3).

[0041] The molar ratio of silicon oxide to aluminum oxide of the twelve-membered ring silicon-aluminum molecular sieve is 9-200, preferably 10-150, and further preferably 10-125.

[0042] According to the present application, the base treatment is used to remove silicon in the twelve-membered ring silicon-aluminum molecular sieve, to make pores, especially mesopores, so as to enrich mesopores and improve the carbon capacity index of the twelve-membered ring silicon-aluminum molecular sieve catalyst. Preferably, the base treatment in step (1) comprises contacting the molecular sieve with a base solution.

[0043] According to the present application, preferably, the conditions of the base treatment comprise a temperature of 40-99℃ and a time of 2-24h.

[0044] The present application does not have a particular limitation on the type of base used in the base treatment, as long as it can remove silicon in the molecular sieve and facilitate the formation of mesopores. Preferably, the base used in the base treatment is selected from at least one of sodium hydroxide, sodium carbonate, potassium hydroxide and potassium carbonate.

[0045] Preferably, the concentration of the base solution is 0.05-5mol / L.

[0046] The present application does not have a particular limitation on the amount of the base solution, as long as it can make the twelve-membered ring silicon-aluminum molecular sieve completely contact with the base solution, for example, by immersing the entire twelve-membered ring silicon-aluminum molecular sieve in the base solution.

[0047] According to the present application, preferably, the number of times of the base treatment is 1-4 times, and further preferably 2-4 times. In this case, the use of multiple base treatments can more, more fully and more uniformly make targeted mesopores, thereby further improving the carbon capacity index of the catalyst and the service life and stability of the target catalyst.

[0048] More preferably, after the previous base treatment, solid-liquid separation (for example, filtration) is performed to obtain a filter cake, the filter cake is dried, and then the second base treatment is performed.

[0049] The present application does not have a particular limitation on the conditions of the drying, and preferably, the conditions of the drying comprise a drying temperature of 80-140℃ and a drying time of 2-24h.

[0050] The present application does not have a particular limitation on the ammonium exchange in step (2), and any method of ammonium exchange in conventional technical means can be used, as long as the molecular sieve obtained by the base treatment is converted into the ammonium type molecular sieve. For example, in a particularly preferred embodiment, the ammonium exchange in step (2) comprises contacting the molecular sieve obtained by the base treatment with an aqueous ammonium salt solution.

[0051] Preferably, the number of times of the ammonium exchange can be one or multiple, which can be freely selected by those skilled in the art according to actual needs.

[0052] Preferably, the conditions of the ammonium exchange comprise a temperature of 50-95℃ and a time of 2-12h.

[0053] Preferably, the liquid-to-solid weight ratio of the ammonium exchange is (1-20):1. It can be understood that the liquid-to-solid weight ratio refers to the weight ratio of the aqueous ammonium salt solution to the molecular sieve obtained by the alkaline treatment.

[0054] Preferably, the concentration of the ammonium salt in the aqueous ammonium salt solution is 0.2-2 mol / L.

[0055] Preferably, the ammonium salt used in the aqueous ammonium salt solution is at least one selected from the group consisting of ammonium nitrate, ammonium sulfate, ammonium chloride and ammonium acetate.

[0056] According to the present application, preferably, the step (2) further comprises: after the ammonium exchange, performing a solid-liquid separation to obtain a filter cake, and then drying the filter cake.

[0057] Preferably, the drying conditions include: a temperature of 80-140℃ and a time of 2-24h.

[0058] In the present application, as long as the water vapor containing the organic amine can be contacted with the ammonium-type molecular sieve in step (3), the specific way of providing the water vapor containing the organic amine and the contact form with the ammonium-type molecular sieve are not particularly limited. Preferably, the treatment of the ammonium-type molecular sieve with the water vapor containing the organic amine in step (3) comprises: contacting an aqueous solution containing the organic amine with the ammonium-type molecular sieve under conditions meeting the vaporization of the organic amine and water. In this preferred embodiment, the specific operation can be introducing the aqueous solution containing the organic amine into a container containing the ammonium-type molecular sieve, and then heating to vaporize the organic amine and water.

[0059] In the present application, the type of the organic amine is not particularly limited. Preferably, the organic amine is at least one selected from the group consisting of methylamine, ethylamine, dimethylamine, trimethylamine, ethylenediamine, diethylamine, triethylamine, n-propylamine and n-butylamine, and further preferably one of ethylamine, diethylamine and triethylamine. The use of this preferred embodiment is more conducive to controlling the pore distribution of the mesopores.

[0060] Preferably, the content of the organic amine in the aqueous solution containing the organic amine is 2-60 wt%, and further preferably 5-50 wt%.

[0061] According to the present application, preferably, the contacting conditions include: a temperature of 250-700℃, preferably 280-550℃, and further preferably 300-500℃; a time of 1-12h, preferably 2-6h; and a mass space velocity of the aqueous solution containing the organic amine of 0.5-15h -1 , preferably 1-8h -1 . The use of this preferred embodiment is more conducive to increasing the ratio of the mesopore volume to the total pore volume.

[0062] In the present application, under the above contacting conditions, the organic amine and water can be vaporized, the organic amine is vaporized together with water, the ammonium type molecular sieve can be fully desilicated, and the mesopore is formed.

[0063] In the present application, the shaping can be performed before or after step (3). According to the present application, in a first specific preferred embodiment, the shaping is performed before step (3) (it is understood that the ammonium type molecular sieve is shaped first), and then step (3) is performed. In a second specific preferred embodiment, step (3) is performed first, and then the molecular sieve obtained by step (3) is shaped. In the present application, the first way is preferred.

[0064] According to the present application, the shaping method is not particularly limited, as long as a catalyst with a desired shape can be prepared. In a preferred embodiment, the shaping comprises mixing the molecular sieve, a binder and an extrusion molding aid, and then performing extrusion molding.

[0065] Preferably, the amount of the binder is 10-300 parts by weight, and the amount of the extrusion molding aid is 1-20 parts by weight, relative to 100 parts by weight of the molecular sieve.

[0066] In the present application, the types and amounts of the extrusion molding aid and the binder are not particularly limited, and a person skilled in the art can select the types and amounts of the extrusion molding aid and the binder within a reasonable range according to the specific situation of the extrusion molding.

[0067] Preferably, the binder comprises at least one of alumina, pseudoboehmite and silica sol.

[0068] Preferably, the extrusion molding aid is selected from at least one of sesbania gum, dextrin and methyl cellulose.

[0069] Preferably, the shaping further comprises, after the extrusion molding, performing optional drying, and then performing calcination.

[0070] In the present application, the conditions of the drying and the calcination are not particularly limited, and conventional drying and calcination in the art can be used, for example, the conditions of the drying preferably comprise a temperature of 50-120℃ and a time of 2-24h. The conditions of the calcination preferably comprise a temperature of 300-600℃ and a time of 2-12h.

[0071] The method is especially suitable for lightening heavy aromatic hydrocarbons and transalkylation reaction. Preferably, the heavy aromatic hydrocarbons are aromatic hydrocarbons with carbon atoms not less than 9, and in a specific preferred embodiment, the heavy aromatic hydrocarbons contain C9 heavy aromatic hydrocarbons and C10 heavy aromatic hydrocarbons, and further, the mass ratio of the C9 heavy aromatic hydrocarbons to the C10 heavy aromatic hydrocarbons is (0.5-10):1.

[0072] According to the present application, preferably, the heavy aromatic hydrocarbon lightening and transalkylation reaction conditions include: temperature is 300-500℃, pressure is 0.5-5MPa, mass space velocity is 1-10h -1 .

[0073] Unless otherwise specified, the pressure in the present application is measured in terms of gauge pressure.

[0074] According to the present application, in addition to the heavy aromatic hydrocarbons, the reaction raw materials can also contain benzene, toluene and the like. Preferably, the molar ratio of the heavy aromatic hydrocarbons to benzene and / or toluene is 1:(0-4), preferably 1:(0-3).

[0075] According to the present application, in order to increase the service life of the catalyst, preferably, the heavy aromatic hydrocarbon lightening and transalkylation reaction method further includes introducing hydrogen, and preferably, the contact conditions are carried out in the presence of hydrogen.

[0076] Preferably, the molar ratio of hydrogen to heavy aromatic hydrocarbons is (0.5-5):1, and further preferably (1-4):1.

[0077] The present application will be described in detail below through examples.

[0078] In the following examples, the mesopore specific surface area, mesopore volume (also referred to as mesopore volume) and total pore volume are measured by low-temperature nitrogen adsorption method, and the test method is as follows: at 77K liquid nitrogen temperature, nitrogen adsorption experiment is carried out in the range of relative pressure of 10 -3 -1 by using a physical adsorption instrument, and an adsorption isotherm is obtained. Based on the desorption branch of the adsorption isotherm, the mesopore distribution of the sample is analyzed by using BJH independent cylinder model; the mesopore volume and micropore volume are measured by t-curve method. The mesopore specific surface area is obtained by linear regression of the BET model.

[0079] The carbon deposition index is measured by thermal analysis method, which refers to the ratio of the carbon deposition amount of the catalyst to the mass of the catalyst after reaction to 100% when the conversion rate of the reaction raw material (heavy aromatic hydrocarbon) is 30% of the initial conversion rate of the fresh catalyst. The carbon deposition amount of the catalyst is tested on a TA SDTQ600 comprehensive thermal analyzer of the United States, and the test method is as follows: under air atmosphere, the temperature is increased from room temperature to 1073K at a rate of 10K·min -1 -1 by using a physical adsorption instrument, and an adsorption isotherm is obtained. Based on the desorption branch of the adsorption isotherm, the mesopore distribution of the sample is analyzed by using BJH independent cylinder model; the mesopore volume and micropore volume are measured by t-curve method. The mesopore specific surface area is obtained by linear regression of the BET model.

[0080] The conversion of heavy aromatics is calculated according to the following formula:

[0081]

[0082] When the raw material is heavy aromatics, the target products are benzene, toluene and xylene, and the selectivity of the target products is calculated according to the following formula:

[0083]

[0084] When the raw material is benzene and heavy aromatics, the target products are toluene and xylene, and the selectivity of the target products is calculated according to the following formula:

[0085]

[0086] When the raw material is toluene and heavy aromatics, the target products are benzene and xylene, and the selectivity of the target products is calculated according to the following formula:

[0087]

[0088] Example 1

[0089] 1. Catalyst preparation

[0090] (1) The ammonium-type mordenite powder (SiO2 / Al2O3 molar ratio of 25) was completely contacted with a 0.5 mol / L sodium hydroxide solution, treated at 95°C for 4 hours, and then subjected to solid-liquid separation. The obtained filter cake was dried at 120°C for 3 hours.

[0091] The dried filter cake was subjected to secondary alkali treatment, completely contacted again with a 0.5 mol / L sodium hydroxide solution, treated at 80°C for 4 hours, and then subjected to solid-liquid separation. The obtained filter cake was dried at 120°C for 3 hours to obtain the alkali-treated molecular sieve S1-A.

[0092] (2) The alkali-treated molecular sieve S1-A was exchanged twice with an ammonium salt aqueous solution (the ammonium salt was ammonium nitrate, and the ammonium salt concentration was 1 mol / L) (the temperature of each exchange was 85°C, and the time was 3 hours; after the first exchange, the solid-liquid separation was performed, 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 solid-liquid separation was performed, and the filter cake was dried at 120°C for 3 hours to obtain the ammonium-type molecular sieve S1-B.

[0093] (3) 100 parts by weight of the ammonium-type molecular sieve S1-B (SiO2 / Al2O3 molar ratio of 20, and BET mesopore specific surface area of 62 m 2 / g and mesopore volume of 0.20 cm 3S1-C was prepared by mixing 100 parts by weight of the zeolite catalyst precursor S1-A, 30 parts by weight of alumina and 5 parts by weight of an extrusion aid, pearl barley powder, kneading well, extruding, drying at 120°C for 3 hours, and calcining at 550°C for 4 hours in air.

[0094] (4) The zeolite catalyst precursor S1-C was treated with water vapor containing ethylamine (specifically, an aqueous solution containing 18% by weight of ethylamine was contacted with S1-C at a temperature of 450°C for 2 hours, and the mass space velocity of the aqueous ethylamine solution was 4 h -1 -1 ), to obtain the zeolite catalyst S1.

[0095] 2. Catalyst evaluation

[0096] Fixed bed reactor volume: 50 ml;

[0097] Catalyst loading: 15 ml;

[0098] Molar ratio of heavy aromatics to benzene and / or toluene: 1:0;

[0099] Mass ratio of C9A and C 10 A in heavy aromatics: 4:1;

[0100] Reaction temperature: 420°C;

[0101] Reaction pressure: 3.0 MPa;

[0102] Mass space velocity of heavy aromatics: 4.0 h -1 -1 ;

[0103] Molar ratio of hydrogen to heavy aromatics: 4.0.

[0104] In a fixed bed reactor, heavy aromatics and hydrogen were contacted with the zeolite catalyst prepared above. The reaction product obtained was cooled by an air condenser, separated by a gas-liquid separator, and liquid products were obtained. The liquid products were sampled and analyzed every 12 hours.

[0105] The initial conversion of heavy aromatics was 45.7%, and after 980 hours of reaction, the conversion of heavy aromatics decreased to 30% of the initial conversion of the fresh catalyst, and the selectivity of the products benzene, toluene and xylene was 87.8%.

[0106] 3. Catalyst carbon capacity index determination

[0107] The DSC-TGA curve of the S1 catalyst after 980 hours of reaction is shown in Figure 1 Figure 1 , and the thermal analysis test results show that the carbon capacity index of the S1 catalyst is 41.2%.

[0108] Comparative Example 1

[0109] The procedure of Example 1 was followed except that the catalyst was prepared differently, specifically, 100 parts by weight of ammonium-type mordenite powder (SiO2 / Al2O3 molar ratio of 25, BET mesopore specific surface area of 22 m 2 / g, mesopore volume of 0.08 cm 3 / g, mesopore volume accounting for 25% of the total pore volume), 30 parts by weight of alumina and extrusion aid (same type and amount as in Example 1) were mixed, kneaded well, extruded, dried at 120°C for 3 hours, calcined at 550°C for 4 hours in air atmosphere to obtain the molecular sieve catalyst BJ-1.

[0110] The pore structure parameters of the obtained molecular sieve catalyst were determined and are shown in Table 1.

[0111] The catalyst evaluation conditions were the same as in Example 1.

[0112] The initial conversion of heavy aromatics was 42.1%, and after 120 hours of reaction, the conversion of the catalyst was reduced to 30% of the initial conversion of the fresh catalyst, and the selectivity of the products benzene, toluene and xylene was 80.2%.

[0113] The thermal analysis test results showed that the carbon capacity index of the catalyst was 9.8%.

[0114] Comparative Example 2

[0115] The procedure of Example 1 was followed except that the catalyst was prepared differently, specifically, step (4) was not used in the preparation of the catalyst, i.e., the water vapor treatment containing ethylamine was not used. The molecular sieve catalyst BJ-2 was obtained.

[0116] The pore structure parameters of the obtained molecular sieve catalyst were determined and are shown in Table 1.

[0117] The catalyst evaluation conditions were the same as in Example 1.

[0118] The initial conversion of heavy aromatics was 43.5%, and after 360 hours of reaction, the conversion of the catalyst was reduced to 30% of the initial conversion of the fresh catalyst, and the selectivity of the products benzene, toluene and xylene was 82.5%.

[0119] The thermal analysis test results showed that the carbon capacity index of the catalyst BJ-2 was 16.9%.

[0120] Example 2

[0121] 1. Catalyst Preparation

[0122] (1) Ammonium-type ZSM-12 powder (SiO2 / Al2O3 molar ratio 65) was contacted with 0.8 mol / L sodium hydroxide solution, treated at 70°C for 4 hours, and then solid-liquid separated. The obtained filter cake was dried at 120°C for 3 hours.

[0123] The dried filter cake was subjected to secondary alkali treatment, contacted again with 2 mol / L sodium hydroxide solution, treated at 70°C for 4 hours, and then solid-liquid separated. The obtained filter cake was dried at 120°C for 3 hours to obtain alkali-treated molecular sieve S2-A.

[0124] (2) The alkali-treated molecular sieve S2-A was exchanged twice with an ammonium salt aqueous solution (ammonium salt was ammonium chloride, and the ammonium salt concentration was 0.5 mol / L) (each exchange was conducted at 95°C for 4 hours; after the first exchange, solid-liquid separation was performed, 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 solid-liquid separation was performed, and the filter cake was dried at 120°C for 3 hours to obtain ammonium-type molecular sieve S2-B.

[0125] (3) 100 parts by weight of the ammonium-type molecular sieve S2-B (SiO2 / Al2O3 molar ratio 55, BET mesopore specific surface area of 162 m 2 / g, mesopore volume of 0.40 cm 3 / g, and mesopore volume accounting for 78% of the total pore volume, which was measured by a low-temperature nitrogen adsorption method) containing 30 parts by weight of SiO2 of silica sol (40 wt%) and 10 parts by weight of an extrusion molding aid pearl millet powder were mixed, kneaded uniformly, extrusion molded, dried at 120°C for 3 hours, and calcined at 550°C for 4 hours in an air atmosphere to obtain a molecular sieve catalyst precursor S2-C.

[0126] (4) The molecular sieve catalyst precursor S2-C was treated with water vapor containing diethylamine (specifically, an aqueous solution containing 20 wt% of diethylamine was contacted with S2-C, the temperature was 500°C, the time was 3 hours, and the mass space velocity of the aqueous solution was 1 h -1 -1 ). A molecular sieve catalyst S2 was obtained.

[0127] 2. Catalyst evaluation

[0128] Fixed bed reactor volume: 50 ml;

[0129] Catalyst loading: 15 ml;

[0130] Molar ratio of heavy aromatics to benzene: 4:6;

[0131] Mass ratio of C9A and C 10 A in heavy aromatics: 4:1;

[0132] Reaction temperature: 460°C;

[0133] Reaction pressure: 3.0 MPa;

[0134] Mass space velocity of benzene + heavy aromatics: 2.0 h -1 ;

[0135] Molar ratio of hydrogen to heavy aromatics was 3:1.

[0136] Benzene, heavy aromatics and hydrogen were contacted with the molecular sieve catalyst prepared above in a fixed bed reactor. The reaction product obtained was cooled by an air condenser and separated by a gas-liquid separator to obtain liquid product. The liquid product was sampled and analyzed every 12 hours.

[0137] The initial conversion of heavy aromatics was 70.0%, and after 960 hours of reaction, the conversion of the catalyst decreased to 30% of the initial conversion of the fresh catalyst, and the selectivity of the products toluene and xylene was 91.4%.

[0138] 3. Determination of carbon capacity index of catalyst

[0139] The thermal analysis test results showed that the carbon capacity index of the S2 catalyst was 27.3%.

[0140] Example 3

[0141] 1. Preparation of catalyst

[0142] (1) The ammonium-type mordenite powder (molar ratio of SiO2 / Al2O3 was 10) was completely contacted with a 4.0 mol / L sodium hydroxide solution, treated at 50°C for 2 hours, and then subjected to solid-liquid separation. The filter cake obtained was dried at 120°C for 3 hours.

[0143] The dried filter cake was subjected to secondary alkali treatment, completely contacted again with a 2.0 mol / L sodium hydroxide solution, treated at 50°C for 20 hours, and then subjected to solid-liquid separation. The filter cake obtained was dried at 120°C for 3 hours to obtain the alkali-treated molecular sieve S3-A.

[0144] (2) The alkali-treated molecular sieve S1-A was exchanged twice with an ammonium salt aqueous solution (the ammonium salt was ammonium nitrate, and the concentration of the ammonium salt was 1 mol / L) (the temperature of each exchange was 90°C, and the time was 4 hours; after the first exchange, the solid-liquid separation and drying at 120°C for 3 hours were performed, and then the same ammonium salt aqueous solution was used for the second exchange). The solid-liquid separation was performed, and the filter cake was dried at 120°C for 3 hours to obtain the ammonium-type molecular sieve S3-B.

[0145] (3) 100 parts by weight of the ammonium-type molecular sieve S1-B (molar ratio of SiO2 / Al2O3 was 8, and the BET mesopore specific surface area measured by the low-temperature nitrogen adsorption method was 223 m 2 / g, and the mesopore volume was 0.36 cm 3S3-C was obtained by mixing 70 parts by weight of silica-alumina, 30 parts by weight of silica, 70 parts by weight of alumina, 10 parts by weight of the extrusion molding aid of pearl millet powder and 10 parts by weight of the extrusion molding aid of dextrin, kneading uniformly, extrusion molding, drying for 12 hours, and calcining at 550°C for 6 hours in an air atmosphere.

[0146] (4) The molecular sieve catalyst precursor S3-C was treated with water vapor containing triethylamine (specifically, an aqueous solution containing 45% by weight of triethylamine was contacted with S3-C, the temperature was 350°C, the time was 6 hours, the mass space velocity of the aqueous solution of triethylamine was 8 h -1 -1, and the weight ratio of the aqueous solution of triethylamine to S3-C was 1:1), to obtain the molecular sieve catalyst S3.

[0147] 2. Catalyst evaluation

[0148] Fixed bed reactor volume: 50 ml;

[0149] Catalyst loading: 15 ml;

[0150] The molar ratio of heavy aromatics to benzene was 1:1;

[0151] The mass ratio of C9A:C 10 in heavy aromatics was 1:2;

[0152] Reaction temperature: 360°C;

[0153] Reaction pressure: 1.0 MPa;

[0154] Mass space velocity of benzene + heavy aromatics: 3.0 h -1 -1;

[0155] The molar ratio of hydrogen to heavy aromatics was 1:1.

[0156] In a fixed bed reactor, heavy aromatics and hydrogen were contacted with the molecular sieve catalyst prepared above. The reaction product obtained was cooled by an air condenser, separated by a gas-liquid separator, and liquid products were obtained. The liquid products were sampled and analyzed every 12 hours.

[0157] The initial conversion rate of heavy aromatics was 65%, and after 1400 hours of reaction, the conversion rate of heavy aromatics decreased to 30% of the initial conversion rate of the fresh catalyst, and the selectivity of the products toluene and xylene was 89%.

[0158] 3. Catalyst carbon capacity index determination

[0159] The thermal analysis test results showed that the carbon capacity index of the S3 catalyst was 33.6%.

[0160] Example 4

[0161] 1. Catalyst preparation

[0162] (1) Ammonium-type ZSM-12 powder (SiO2 / Al2O3 molar ratio 121) was contacted with 0.2 mol / L sodium hydroxide solution, treated at 95°C for 12 hours, and then solid-liquid separated. The obtained filter cake was dried at 120°C for 3 hours.

[0163] The dried filter cake was subjected to secondary alkali treatment, contacted again with 2 mol / L sodium hydroxide solution, treated at 70°C for 4 hours, and then solid-liquid separated. The obtained filter cake was dried at 120°C for 3 hours to obtain alkali-treated molecular sieve S4-A.

[0164] (2) The alkali-treated molecular sieve S4-A was exchanged twice with ammonium salt aqueous solution (ammonium salt was ammonium nitrate, and the ammonium salt concentration was 1.0 mol / L) (each exchange was conducted at 90°C for 4 hours; after the first exchange, solid-liquid separation was conducted, 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 solid-liquid separation was conducted, and the filter cake was dried at 120°C for 3 hours to obtain ammonium-type molecular sieve S4-B.

[0165] (3) 100 parts by weight of the ammonium-type molecular sieve S4-B (SiO2 / Al2O3 molar ratio 79, BET mesopore specific surface area 107 m 2 / g, mesopore volume 0.24 cm 3 / g, mesopore volume accounting for 39% of the total pore volume, which was measured by low-temperature nitrogen adsorption method), 100 parts by weight of alumina, and 10 parts by weight of esparto powder were mixed, kneaded uniformly, extrusion-molded, dried at 120°C for 3 hours, and calcined at 550°C for 4 hours in air atmosphere to obtain molecular sieve catalyst precursor S4-C.

[0166] (4) The molecular sieve catalyst precursor S4-C was treated with water vapor containing diethylamine (specifically, water solution containing 5% by weight of diethylamine was contacted with S4-C, the temperature was 500°C, the time was 3 hours, and the mass space velocity of the water solution was 2 h -1 ), to obtain molecular sieve catalyst S4.

[0167] 2. Catalyst evaluation

[0168] Fixed bed reactor volume: 50 ml;

[0169] Catalyst loading: 15 ml;

[0170] Molar ratio of heavy aromatics to toluene: 1:3;

[0171] Mass ratio of C9A and C 10 A in heavy aromatics: 2:1;

[0172] Reaction temperature: 380°C;

[0173] Reaction pressure: 4.0 MPa;

[0174] Mass space velocity of toluene + heavy aromatic hydrocarbon: 6.0 h -1 ;

[0175] The molar ratio of hydrogen to heavy aromatic hydrocarbon was 2:1.

[0176] Toluene, heavy aromatic hydrocarbon and hydrogen were contacted with the molecular sieve catalyst prepared above in a fixed bed reactor. The reaction product obtained was cooled by an air condenser and separated by a gas-liquid separator to obtain liquid product. The liquid product was sampled and analyzed every 12 hours.

[0177] The initial conversion rate of heavy aromatic hydrocarbon was 54.1%, and after 1200 hours of reaction, the conversion rate of the catalyst decreased to 30% of the initial conversion rate of the fresh catalyst, and the selectivity of the product benzene and xylene was 91.0%.

[0178] 3. Catalyst carbon capacity index determination

[0179] The thermal analysis test results showed that the carbon capacity index of the S4 catalyst was 35.6%.

[0180] Example 5

[0181] The method of Example 1 was followed, except that in the preparation of the catalyst, the process parameters used in step (4) were different, specifically, the mass space velocity of the aqueous ethylamine solution was 10 h -1 . The test results are shown in Table 1.

[0182] Example 6

[0183] The method of Example 1 was followed, except that in the preparation of the catalyst, different process parameters were used in step (4), specifically, the temperature in step (4) was 270°C. The test results are shown in Table 1.

[0184] Example 7

[0185] The method of Example 1 was followed, except that in the preparation of the catalyst, different types of organic amines were used in step (4), specifically, n-butylamine was used. The test results are shown in Table 1.

[0186] Example 8

[0187] The method of Example 1 was followed, except that in the preparation of the catalyst, different types of organic amines were used in step (4), specifically, n-propylamine was used. The test results are shown in Table 1.

[0188] Table 1

[0189]

[0190]

[0191] As can be seen from the results in Table 1, the method of the present application has excellent aromatic conversion rate, and higher selectivity and stability of target products in the lightening of heavy aromatic hydrocarbons and transalkylation reaction, and can be used for industrial production of the lightening of heavy aromatic hydrocarbons and transalkylation.

[0192] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application, and all fall within the protection scope of the present application.

Claims

1. A method for lightening heavy aromatics and transferring alkyl groups, the method comprising: Under the conditions of heavy aromatics lightening and alkyl transfer reaction, heavy aromatics and optionally benzene and / or toluene are contacted with the catalyst; The catalyst is a modified twelve-membered cyclic silica-alumina molecular sieve, wherein the silica / alumina molar ratio of the modified twelve-membered cyclic silica-alumina molecular sieve is 6-100, and the mesoporous specific surface area is 30-300 m². 2 / g, mesopore volume accounts for 20-95% of the total pore volume; The preparation method of the modified twelve-membered ring silica-alumina molecular sieve includes the following steps: (1) The twelve-membered ring silica-alumina molecular sieve is subjected to alkali treatment; (2) The molecular sieve obtained by alkali treatment is subjected to ammonium exchange to obtain ammonium-type molecular sieve; (3) The ammonium molecular sieve is treated with water vapor containing organic amine; The method also includes molding performed before and / or after step (3); The silica / alumina molar ratio of the twelve-membered ring silica-alumina molecular sieve is 9-200; Step (3) involves treating the ammonium molecular sieve with water vapor containing organic amines, which includes: Under conditions that satisfy the vaporization of organic amines and water, an aqueous solution containing organic amines is contacted with an ammonium molecular sieve. The contact conditions include: a temperature of 250-700℃, a time of 1-10 h, and a mass hourly space velocity (HHSV) of 0.5-15 h⁻¹ for the aqueous solution containing organic amines. -1 .

2. The method according to claim 1, wherein, The modified twelve-membered ring silica-alumina molecular sieve has a silica / alumina molar ratio of 8-80; and / or, The modified twelve-membered ring silica-alumina molecular sieve has a mesoporous specific surface area of ​​50-250 m². 2 / g; and / or, The modified twelve-membered ring silica-alumina molecular sieve has a mesopore volume of 0.1-0.5 cm³. 3 / g; and / or, The modified twelve-membered ring silica-alumina molecular sieve has a mesopore volume accounting for 25-90% of the total pore volume.

3. The method according to claim 1 or 2, wherein, The modified twelve-membered ring silica-alumina molecular sieve is mordenite zeolite and / or ZSM-12 molecular sieve.

4. The method according to claim 1 or 2, wherein, The silica / alumina molar ratio of the twelve-membered ring silica-alumina molecular sieve is 10-150.

5. The method according to claim 1, wherein, The alkali treatment in step (1) includes contacting the molecular sieve with an alkali solution.

6. The method according to claim 5, wherein, The conditions for the alkali treatment include: a temperature of 40-99℃ and a time of 2-24h.

7. The method according to claim 5, wherein, The alkali used in the alkali treatment is selected from at least one of sodium hydroxide, sodium carbonate, potassium hydroxide, and potassium carbonate.

8. The method according to claim 5, wherein, The concentration of the alkaline solution is 0.05-5 mol / L.

9. The method according to claim 5, wherein, The number of alkali treatments is 1-4 times.

10. The method according to claim 9, wherein, The alkali treatment is performed 2-4 times.

11. The method according to claim 1, wherein, The organic amine is selected from at least one of methylamine, ethylamine, dimethylamine, trimethylamine, ethylenediamine, diethylamine, triethylamine, n-propylamine, and n-butylamine.

12. The method according to claim 1, wherein, The aqueous solution containing organic amines contains 2-60% by weight of organic amines.

13. The method according to claim 12, wherein, The aqueous solution containing organic amines contains 5-50% by weight of organic amines.

14. The method according to claim 1, wherein, The contact conditions include: a temperature of 280-550°C; a time of 2-6 hours; and a mass hourly space velocity (MSV) of 1-8 h⁻¹ for the aqueous solution containing organic amines. -1 .

15. The method according to claim 1, wherein, The molding process involves mixing molecular sieves, binders, and extrusion molding aids, followed by extrusion molding.

16. The method according to claim 15, wherein, The amount of the binder is 10-300 parts by weight relative to 100 parts by weight of molecular sieve, and the amount of the extrusion molding aid is 1-20 parts by weight.

17. The method according to claim 1 or 2, wherein, The heavy aromatic hydrocarbon is an aromatic hydrocarbon with not less than 9 carbon atoms.

18. The method according to claim 17, wherein, The heavy aromatics contain both C9 and C10 heavy aromatics.

19. The method according to claim 1 or 2, wherein, The conditions for the heavy aromatic hydrocarbon lightening and alkyl transfer reaction include: a temperature of 300-500℃, a pressure of 0.5-5MPa, and a mass hourly space velocity of 1-10h. -1 .

20. The method according to claim 1 or 2, wherein, The molar ratio of the heavy aromatic hydrocarbon to benzene and / or toluene is 1:(0-4).

21. The method according to claim 20, wherein, The molar ratio of the heavy aromatic hydrocarbon to benzene and / or toluene is 1:(0-3).

22. The method according to claim 1 or 2, wherein, The contact takes place in the presence of hydrogen.

23. The method according to claim 22, wherein, The molar ratio of hydrogen to heavy aromatics is (0.5-5):1.

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