Transalkylation catalyst, preparation method and application thereof, and aromatic hydrocarbon liquid-phase transalkylation method

Abstract

The invention relates to the field of catalysts, and discloses a transalkylation catalyst, a preparation method and application thereof, and an aromatic hydrocarbon liquid phase transalkylation method. The transalkylation catalyst comprises a Beta / ZSM-12 symbiotic molecular sieve, titanium dioxide and a binder. According to the transalkylation catalyst provided by the invention, the Beta / ZSM-12 symbiotic molecular sieve is matched with the titanium dioxide, so that the transalkylation reaction of a material containing toluene and C9 < + > aromatic hydrocarbon is promoted. Under a liquid phase reaction condition, the catalyst also has relatively high aromatic hydrocarbon conversion rate and xylene selectivity, and the preparation method of the catalyst is simple and can be used in industrial production of p-xylene.

Description

Technical Field

[0001] The invention relates to the field of catalysts, and in particular to an alkyl transfer catalyst, a preparation method and application thereof, and a method for liquid-phase alkyl transfer of aromatic hydrocarbons. Background Art

[0002] As an important organic chemical raw material, xylene has a wide range of uses in industry. It can be used as a solvent in the coating, resin, dye, ink and other industries; it can be used as a synthetic monomer or solvent in the pharmaceutical, explosive, pesticide and other industries; it can also be used as a high-octane gasoline component. The most used product in xylene is para-xylene, which can be used to produce polyester, and the demand is also increasing day by day. The main methods for producing xylene in industry include: 1) using naphtha as a raw material through a series of processes such as catalytic reforming, separation and purification to obtain xylene and other high-added products; 2) using toluene disproportionation and transalkylation technology, that is, toluene and C9 aromatics are converted into benzene and xylene under the action of a catalyst. The reaction mainly includes: toluene disproportionation reaction and transalkylation reaction. Toluene disproportionation reaction generally refers to the generation of one benzene molecule and one xylene molecule by the disproportionation reaction of two toluene molecules. Transalkylation reaction generally refers to the generation of two xylene molecules by one toluene molecule and one trimethylbenzene molecule under the action of a catalyst.

[0003] Conventional toluene disproportionation and transalkylation process technology is usually carried out at a relatively high reaction temperature (350-410°C). The materials are mixed in the gas phase and converted in contact with the catalyst. A large amount of hydrogen is usually consumed during the reaction. The target products benzene and xylene are separated from the products. The unreacted useful materials are separated and recycled for conversion. Usually, there will be excessive cracking during the reaction, resulting in aromatic losses, and a small amount of heavy aromatic by-products are produced. Since they cannot be converted, they need to be discharged, which increases energy consumption and production costs. At present, higher requirements are put forward for how refining enterprises can save energy, reduce emissions, improve quality and increase efficiency.

[0004] Although major foreign oil companies have developed new disproportionation and transalkylation catalysts in recent years, the energy consumption required for the operation of the equipment is still high. Therefore, it is proposed to develop liquid-phase aromatic transalkylation catalysts and process technologies to alleviate the high energy consumption of refineries in the production of xylene. Liquid-phase aromatic transalkylation technology is a process in which the reactants are mixed in liquid form and contacted with the catalyst for conversion. The reaction temperature is usually 200-330°C. It has the advantages of low energy consumption, low aromatic loss, low by-products, and high xylene selectivity. Although hydrogen is also required to participate in the reaction during the reaction, the amount used is much lower than that of the gas phase reaction. It only needs to dissolve the hydrogen in the reactants.

[0005] CN108779047A discloses a method for liquid phase aromatic hydrocarbon transalkylation. The catalyst used in the invention comprises a molecular sieve having a 3-dimensional 12-membered ring skeleton structure and a molecular sieve having a 1-dimensional 12-membered ring skeleton structure. The pore channels are at least The method includes performing a transalkylation process wherein at least a portion of the feed to the transalkylation process is in a liquid phase, and some embodiments include a liquid phase transalkylation process for a naphthalene-containing feed stream.

[0006] CN109790084A discloses a method for transalkylation of heavy aromatics, and a method for producing xylene from C9+ aromatics, comprising contacting a first feed containing C9+ aromatics with a catalyst under effective vapor phase dealkylation conditions in the presence of 0wt% or more hydrogen to dealkylate a portion of the C9+ aromatics and produce a first product containing benzene, toluene and residual C9+ aromatics. A second feed containing C9+ aromatics and benzene and / or toluene is contacted with a second catalyst under effective liquid phase C9+ transalkylation conditions to transalkylate at least a portion of the C9+ aromatics and produce a second product containing xylene.

[0007] CN109803944A discloses a method for disproportionation and transalkylation of heavy aromatics, comprising: (a) contacting a feedstock containing toluene with a first catalyst under effective gas-phase toluene disproportionation conditions to disproportionate the toluene and produce a first product comprising benzene, unreacted toluene and p-xylene in greater amounts than the equilibrium amount; and (b) contacting a feedstock containing C9+ aromatics and benzene with a second catalyst under effective C9+ transalkylation conditions in the presence of 0 wt% or more hydrogen having a hydrogen / hydrocarbon molar ratio of 0-10 to transalkylate the C9+ aromatics and produce a second product containing xylene.

[0008] The current related technologies have problems such as low aromatics conversion efficiency and low xylene selectivity under liquid phase conditions. Summary of the invention

[0009] The purpose of the present invention is to overcome the problems of low aromatic conversion rate and low xylene selectivity in the aromatic liquid phase transalkylation reaction in the prior art, and to provide an alkylation transfusion catalyst, a preparation method and application thereof, and an aromatic liquid phase transalkylation method. The catalyst is beneficial to promoting the aromatic liquid phase transalkylation reaction and has the characteristics of high aromatic conversion rate and high xylene selectivity.

[0010] In order to achieve the above object, the first aspect of the present invention provides an alkyl transfer catalyst, wherein the catalyst comprises Beta / ZSM-12 intergrowth molecular sieve, titanium dioxide and a binder.

[0011] Preferably, based on the total amount of the catalyst, the weight percentage of the Beta / ZSM-12 intergrowth molecular sieve is 67-88%, preferably 74-85%; the weight percentage of the titanium dioxide is 2-8%, preferably 3-6%; the weight percentage of the binder is 10-25%, preferably 10-20%.

[0012] A second aspect of the present invention provides a method for preparing the above-mentioned transalkylation catalyst, the method comprising the following steps:

[0013] (1) mixing Beta / ZSM-12 intergrowth molecular sieve, titanium dioxide, a binder, and optionally an extrusion aid and a peptizing agent in the presence of a solvent;

[0014] (2) The mixed material obtained in step (1) is molded, and then dried and calcined.

[0015] The third aspect of the present invention provides use of the transalkylation catalyst described in the first aspect in a liquid phase transalkylation reaction of aromatic hydrocarbons.

[0016] The fourth aspect of the present invention provides a method for liquid phase transalkylation of aromatic hydrocarbons, comprising: contacting a mixture containing toluene and C9+ aromatic hydrocarbons with a catalyst in the presence of hydrogen and under liquid phase reaction conditions, wherein the catalyst is selected from the transalkylation catalyst described in the first aspect.

[0017] Through the above technical solution, the beneficial effects obtained by the present invention are as follows:

[0018] The transalkylation catalyst provided by the present invention adopts Beta / ZSM-12 co-growth molecular sieve and titanium dioxide, which is conducive to promoting the transalkylation reaction of materials containing toluene and C9+ aromatics. Under liquid phase reaction conditions, the catalyst also has a high aromatic conversion rate and xylene selectivity. The preparation method of the catalyst is simple and can be used in the industrial production of p-xylene. DETAILED DESCRIPTION

[0019] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0020] A first aspect of the present invention provides an alkyl transfer catalyst, wherein the catalyst comprises Beta / ZSM-12 intergrowth molecular sieve, titanium dioxide and a binder.

[0021] In the present invention, titanium dioxide is added to cooperate with the Beta / ZSM-12 symbiotic molecular sieve, and the titanium dioxide adjusts the acid content of the symbiotic molecular sieve, improves the stability of the transalkylation catalyst, and inhibits the occurrence of side reactions.

[0022] In the present invention, the intergrown molecular sieve refers to a molecular sieve material containing two or more crystal structures that is directly synthesized during the synthesis process.

[0023] In the present invention, Beta / ZSM-12 symbiotic molecular sieves are used. The material contains two molecular sieves with different structures, namely, Beta molecular sieve with three-dimensional twelve-membered rings and ZSM-12 molecular sieve with one-dimensional twelve-membered rings. Compared with simple mechanical mixing of Beta molecular sieve and ZSM-12 molecular sieve, the symbiotic molecular sieve has an interconnected composite pore structure, and reactants are more easily accessible to active sites, and the complementary acid distribution can synergistically catalyze and improve the activity of transalkylation reaction under liquid phase conditions.

[0024] According to the present invention, preferably, based on the total amount of the catalyst, the weight percentage of the Beta / ZSM-12 intergrowth molecular sieve is 67-88%, preferably 74-85%; the weight percentage of the titanium dioxide is 2-8%, preferably 3-6%; the weight percentage of the binder is 10-25%, preferably 10-20%.

[0025] In the present invention, the contents of Beta / ZSM-12 symbiotic molecular sieve, titanium dioxide and binder in the catalyst are calculated by feeding amount.

[0026] According to the present invention, preferably, the SiO2 / Al2O3 molar ratio of the Beta / ZSM-12 intergrowth molecular sieve is 10-40, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, or any range therebetween, preferably 10-20.

[0027] In the present invention, the Beta / ZSM-12 symbiotic molecular sieve with a lower SiO2 / Al2O3 molar ratio is used, and the molecular sieve has a larger acid content, which helps to increase the active sites in the molecular sieve. Under low-temperature reaction conditions in the liquid phase, the alkyl transfer catalyst can also have high activity, high aromatic conversion rate, and high xylene selectivity.

[0028] In the present invention, inductively coupled plasma atomic emission spectrometry (ICP-AES) is used to determine the silicon-aluminum molar ratio SiO2 / Al2O3 of the Beta / ZSM-12 intergrowth molecular sieve, and the testing instrument is: Varian 725-ES series ICP-AES instrument.

[0029] According to the present invention, preferably, the average grain size of the Beta / ZSM-12 intergrowth molecular sieve is less than 500nm, preferably 100-300nm. The average grain size of the Beta / ZSM-12 intergrowth molecular sieve is obtained by observation using an XL30E scanning electron microscope of Philips of the Netherlands. In the present invention, the Beta / ZSM-12 intergrowth molecular sieve has a small average grain size, a large specific surface area, many active sites and is more accessible, and the prepared catalyst has high catalytic activity.

[0030] The binder type of the present invention has a wide range of choices and can be a conventional binder in the art, so that the Beta / ZSM-12 intergrowth molecular sieve and titanium dioxide are better combined to improve the catalytic activity of the prepared catalyst. According to the present invention, preferably, the binder is silicon oxide and / or aluminum oxide.

[0031] According to the present invention, preferably, in the Beta / ZSM-12 symbiotic molecular sieve, the symbiotic ratio of Beta molecular sieve and ZSM-12 molecular sieve is 0.25-4:1, for example, 0.25:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, or a range therebetween, preferably 0.5-2: 1. The use of a specific symbiotic ratio of Beta / ZSM-12 symbiotic molecular sieve is not only more conducive to the diffusion of hydrocarbon molecules, but also improves the conversion rate of aromatics when carrying out transalkylation reaction under liquid phase reaction conditions, and is more conducive to improving xylene selectivity.

[0032] In the present invention, the intergrowth ratio is the weight ratio of Beta molecular sieve to ZSM-12 molecular sieve in the Beta / ZSM-12 intergrowth molecular sieve. The intergrowth ratio is obtained by calculating the ratio of the characteristic peak areas of the two crystal phases in the XRD spectrum.

[0033] In the present invention, the source of the Beta / ZSM-12 symbiotic molecular sieve is not particularly limited, and it can be commercially available or prepared by an existing preparation method. The Beta / ZSM-12 symbiotic molecular sieve that meets the above parameter requirements is used in combination with titanium dioxide to effectively improve the catalytic activity of the catalyst.

[0034] According to a specific embodiment of the present invention, the Beta / ZSM-12 intergrowth molecular sieve is prepared by the following method:

[0035] (A) An inorganic base, a quaternary ammonium salt, a silicon source, an aluminum source and deionized water are mixed, and the reaction mixture is calculated by molar ratio: SiO2 / Al2O3=15-50:1, and the quaternary ammonium salt TEA + / SiO2=0.1-0.5:1, inorganic base OH - / SiO2=0.2-0.5:1, H2O / SiO2=15-100:1, stirring at 25-90℃, aging;

[0036] (B) After the crystallization treatment, the product is cooled and taken out, filtered, exchanged, washed, dried and calcined to obtain the Beta / ZSM-12 intergrowth molecular sieve.

[0037] In the present invention, the crystallization conditions include: a crystallization temperature of 120-200° C., a crystallization time of 48-96 hours, and the crystallization reaction is carried out in a closed container under autogenous pressure.

[0038] In the present invention, the calcination condition of the symbiotic molecular sieve is calcination at 450-650° C. for 3-24 hours in an air atmosphere.

[0039] In the present invention, the filtering, exchanging, washing and drying are conventional operations in the art, and those skilled in the art can make adaptive adjustments, which will not be described in detail here.

[0040] In the present invention, the inorganic base, quaternary ammonium salt, silicon source and aluminum source are conventional inorganic bases, quaternary ammonium salts, silicon source and aluminum source in the art, and the Beta / ZSM-12 symbiotic molecular sieve required for the above-mentioned transalkylation catalyst can be obtained.

[0041] In the present invention, preferably, the inorganic base is potassium hydroxide and / or sodium hydroxide. Preferably, the silicon source is selected from at least one of water glass, silica sol, silica gel and ethyl orthosilicate. Preferably, the quaternary ammonium salt TEA + At least one selected from tetraethylammonium bromide, tetraethylammonium chloride and tetraethylammonium hydroxide. Preferably, the aluminum source is selected from at least one selected from pseudo-boehmite, sodium metaaluminate, aluminum sulfate and aluminum nitrate.

[0042] The second aspect of the present invention provides a method for preparing the transalkylation catalyst according to the first aspect, the method comprising the following steps:

[0043] (1) in the presence of a solvent, mixing Beta / ZSM-12 intergrowth molecular sieve, titanium dioxide, a binder, and optionally an extrusion aid and a peptizing agent;

[0044] (2) The mixed material obtained in step (1) is molded, and then dried and calcined.

[0045] In the present invention, the added amounts of the Beta / ZSM-12 symbiotic molecular sieve, titanium dioxide and binder are based on the contents of the Beta / ZSM-12 symbiotic molecular sieve, titanium dioxide and binder in the catalyst described in the first aspect.

[0046] In the present invention, unless otherwise specified, the term "optional" means containing or not containing, adding or not adding, using or not using. Specifically, in step (1) of the present invention, an extrusion aid and / or a peptizing agent may be added, or no extrusion aid and a peptizing agent may be added.

[0047] The types of the extrusion aids of the present invention are well known to those skilled in the art. According to the present invention, preferably, the extrusion aid is selected from at least one of sesbania powder, methylcellulose, hydroxypropyl methylcellulose and dextrin.

[0048] In the present invention, the amount of the extrusion aid is not particularly limited, and those skilled in the art can make adaptive adjustments as needed to ensure that subsequent molding proceeds smoothly. Preferably, the amount of the extrusion aid is 1-5%, preferably 1-3%, of the total weight of the Beta / ZSM-12 intergrowth molecular sieve, titanium dioxide and binder on a dry basis.

[0049] In the present invention, the dry basis refers to the condition of roasting at 550°C for 3h.

[0050] In the present invention, there is no particular limitation on the type of the peptizing agent, and it can be any peptizing agent commonly used in the art. Preferably, the peptizing agent is an inorganic acid, and more preferably, the peptizing agent is nitric acid.

[0051] The present invention has no particular limitation on the manner of adding the Beta / ZSM-12 symbiotic molecular sieve, titanium dioxide, binder, extrusion aid, and peptizing agent, and they can be added separately or together.

[0052] According to a preferred embodiment of the present invention, the Beta / ZSM-12 intergrowth molecular sieve titanium dioxide, a binder and an optional extrusion aid are firstly mixed uniformly, and then an aqueous solution containing a peptizing agent is added.

[0053] According to the present invention, preferably, the amount of the peptizing agent is 2-8% of the weight of the binder on a dry basis. There is no particular limitation on the amount of the aqueous solution containing the peptizing agent, and those skilled in the art can make adaptive adjustments according to the molding conditions. Preferably, the amount of water in the aqueous solution containing the peptizing agent is 20-60% of the total weight of the Beta / ZSM-12 intergrowth molecular sieve, titanium dioxide and binder on a dry basis.

[0054] The present invention has no specific limitation on the mixing conditions in step (1), which can be appropriately selected according to the specific situation, as long as the purpose of uniform mixing can be achieved.

[0055] The present invention has no particular limitation on the molding of step (2), and can be carried out according to conventional molding methods in the art. For example, it can be, but is not limited to, extrusion molding, spray molding or compression molding. In the present invention, extrusion molding is preferably used, and the specific method is well known to those skilled in the art, and will not be described in detail here.

[0056] According to a specific embodiment of the present invention, the mixture obtained in step (1) is first kneaded into a dough shape, and then extruded into a cylindrical strip shape.

[0057] The present invention has no particular limitation on the drying conditions, and can be appropriately selected according to the specific situation, as long as the purpose of drying can be achieved. Preferably, the drying conditions include: a temperature of 60-150° C. and a time of 3-12 hours.

[0058] The present invention has no particular limitation on the calcination conditions, and the calcination can be carried out according to conventional methods in the art. The calcination is generally carried out in an air atmosphere, and the air atmosphere includes a flowing atmosphere or a static atmosphere. According to the present invention, preferably, the calcination conditions include: a temperature of 450-650°C, preferably 500-600°C; and a time of 2-10h, preferably 3-8h.

[0059] The third aspect of the present invention provides use of the transalkylation catalyst described in the first aspect in a liquid phase transalkylation reaction of aromatic hydrocarbons.

[0060] The fourth aspect of the present invention provides a method for liquid phase transalkylation of aromatic hydrocarbons, comprising: contacting a mixture containing toluene and C9+ aromatic hydrocarbons with a catalyst in the presence of hydrogen and under liquid phase reaction conditions, wherein the catalyst is selected from the transalkylation catalyst described in the first aspect.

[0061] According to the present invention, preferably, the liquid phase reaction conditions include: temperature of 200-350°C, preferably 250-300°C; pressure of 2-5MPa, preferably 3-4MPa; mass space velocity of 0.5-2.5h -1 , preferably 1-2h -1 .

[0062] The "in the presence of hydrogen" mentioned in the present invention is a conventional choice in the art, and various hydrogen-containing gases can be used to implement the present invention, as long as the amount of hydrogen in the hydrogen-containing gas can meet the conditions for the liquid phase reaction of the mixture of toluene and C9+ aromatics of the present invention. The present invention has no specific requirements for this, and will not be described in detail here.

[0063] In the present invention, the content range of toluene and C9+ aromatics in the mixed material containing toluene and C9+ aromatics is relatively wide, and those skilled in the art can make adaptive adjustments according to the conditions of the liquid phase reaction. Preferably, the weight content of toluene in the mixed material is 30-70%, and the weight content of C9+ aromatics is 30-70%.

[0064] The present invention has a wide range of selection for the types of C9+ aromatics, which can be mixed with toluene to react in liquid phase to generate xylene. The C9+ aromatics are selected from at least one of aromatics with 9 or more carbon atoms.

[0065] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in the present invention are based on weight, unless the weight basis does not conform to the common understanding of those skilled in the art.

[0066] According to a particularly preferred embodiment of the present invention, a method for preparing a transalkylation catalyst comprises the following steps:

[0067] (1) in the presence of a solvent, mixing Beta / ZSM-12 intergrowth molecular sieve, titanium dioxide, a binder, and optionally an extrusion aid and a peptizing agent;

[0068] (2) forming the mixed material obtained in step (1), and then drying and calcining;

[0069] Based on the total amount of the catalyst, the weight percentage of the Beta / ZSM-12 intergrowth molecular sieve is 74-85%; the weight percentage of the titanium dioxide is 3-6%; the weight percentage of the binder is 10-20%;

[0070] In the Beta / ZSM-12 symbiotic molecular sieve, the symbiotic ratio of the Beta molecular sieve to the ZSM-12 molecular sieve is 0.5-2:1.

[0071] The present invention will be described in detail below through examples and comparative examples. In the following examples and comparative examples,

[0072] The aromatics conversion is defined as follows:

[0073]

[0074] The xylene selectivity is defined as follows:

[0075]

[0076] The content of aromatic hydrocarbons was determined by gas chromatography, and the testing instrument was Agilent Technologies 7890A GCSystem;

[0077] The test methods for the average crystal size and silicon-aluminum molar ratio of Beta / ZSM-12 intergrowth molecular sieve are described in the aforementioned specification and will not be repeated here;

[0078] Unless otherwise specified, all reagents and materials used were commercially available, and the room temperature was 25°C.

[0079] Preparation Example 1 of Beta / ZSM-12 Symbiotic Molecular Sieve

[0080] The molar ratio of NaOH, tetraethylammonium hydroxide, silica gel, pseudo-boehmite and deionized water is: SiO2 / Al2O3=15:1, TEA + / SiO2=0.2:1,OH - / SiO2=0.4:1, H2O / SiO2=20:1, stirred at 50℃, and aged for 3h; placed in a sealed container and crystallized at 160℃ under autogenous pressure for 72h; the crystallized product was cooled and taken out, filtered, exchanged, washed, dried, and calcined at 550℃ in air atmosphere for 4h to obtain Beta / ZSM-12 symbiotic molecular sieve with SiO2 / Al2O3 molar ratio of 10.

[0081] Beta / ZSM-12 symbiotic molecular sieve preparation example 2-9

[0082] Beta / ZSM-12 intergrowth molecular sieve was prepared according to the method of Preparation Example 1, and the addition amount of each component and the reaction conditions were changed so that the prepared Beta / ZSM-12 intergrowth molecular sieve met the conditions for preparing an alkyl transfer catalyst. The SiO2 / Al2O3 molar ratio, average grain size and intergrowth ratio of the Beta / ZSM-12 intergrowth molecular sieve are shown in Table 1.

[0083] Example 1

[0084] 77 g of the Beta / ZSM-12 symbiotic molecular sieve of Preparation Example 1 (SiO2 / Al2O3 molar ratio of 10, average grain size of 300 nm, Beta to ZSM-12 symbiotic ratio of 2:1), 8 g of TiO2 powder, 15 g of alumina, and 2.5 g of sesbania powder were mixed evenly in a kneader. 45 g of an aqueous solution containing 1 g of nitric acid was slowly added to the kneader and kneaded for 30 minutes to obtain a dough. The dough was extruded through a die into a cylindrical strip with a diameter of 1.7 mm and a length of 2 mm. Catalyst A was obtained after drying at 120°C for 6 h and calcining at 550°C in air atmosphere for 4 h, as shown in Table 1 for details.

[0085] Example 2

[0086] 83 g of the Beta / ZSM-12 symbiotic molecular sieve of Preparation Example 1 (SiO2 / Al2O3 molar ratio of 10, average grain size of 300 nm, Beta to ZSM-12 symbiotic ratio of 2:1), 2 g of TiO2 powder, 15 g of alumina, and 2.5 g of sesbania powder were mixed evenly in a kneader. 45 g of an aqueous solution containing 1 g of nitric acid was slowly added to the kneader and kneaded for 30 minutes to obtain a dough. The dough was extruded through a die into a cylindrical strip with a diameter of 1.7 mm and a length of 2 mm. Catalyst B was obtained after drying at 120°C for 6 h and calcining at 550°C in air atmosphere for 4 h, as shown in Table 1 for details.

[0087] Example 3

[0088] 80 g of the Beta / ZSM-12 symbiotic molecular sieve (SiO2 / Al2O3 molar ratio of 10, average grain size of 300 nm, Beta to ZSM-12 symbiotic ratio of 2:1) of Preparation Example 1, 5 g of TiO2 powder, 15 g of alumina, and 2.5 g of sesbania powder were mixed evenly in a kneader, 45 g of an aqueous solution containing 1 g of nitric acid was slowly added to the kneader, and the mixture was kneaded for 30 minutes to obtain a dough, which was extruded through a die into a cylindrical strip with a diameter of 1.7 mm and a length of 2 mm. Catalyst C was obtained after drying at 120°C for 6 h and calcining at 550°C in air atmosphere for 4 h, as shown in Table 1 for details.

[0089] Example 4

[0090] 80 g of the Beta / ZSM-12 symbiotic molecular sieve of Preparation Example 2 (SiO2 / Al2O3 molar ratio of 10, average grain size of 300 nm, Beta to ZSM-12 symbiotic ratio of 4:1), 5 g of TiO2 powder, 15 g of alumina, and 2.5 g of sesbania powder were mixed evenly in a kneader, 45 g of an aqueous solution containing 1 g of nitric acid was slowly added to the kneader, and kneaded for 30 minutes to obtain a dough, which was extruded through a die into a cylindrical strip with a diameter of 1.7 mm and a length of 2 mm. Catalyst D was obtained after drying at 120°C for 6 h and calcining at 550°C in air atmosphere for 4 h, as shown in Table 1 for details.

[0091] Example 5

[0092] 80 g of the Beta / ZSM-12 symbiotic molecular sieve of Preparation Example 3 (SiO2 / Al2O3 molar ratio of 10, average grain size of 300 nm, Beta to ZSM-12 symbiotic ratio of 0.5:1), 5 g of TiO2 powder, 15 g of alumina, and 2.5 g of sesbania powder were mixed evenly in a kneader. 45 g of an aqueous solution containing 1 g of nitric acid was slowly added to the kneader and kneaded for 30 minutes to obtain a dough. The dough was extruded through a die into a cylindrical strip with a diameter of 1.7 mm and a length of 2 mm. Catalyst E was obtained after drying at 120°C for 6 h and calcining at 550°C in air atmosphere for 4 h, as shown in Table 1.

[0093] Example 6

[0094] 80 g of the Beta / ZSM-12 symbiotic molecular sieve of Preparation Example 4 (SiO2 / Al2O3 molar ratio of 10, average grain size of 300 nm, Beta to ZSM-12 symbiotic ratio of 0.25:1), 5 g of TiO2 powder, 15 g of alumina, and 2.5 g of sesbania powder were mixed evenly in a kneader, 45 g of an aqueous solution containing 1 g of nitric acid was slowly added to the kneader, and the mixture was kneaded for 30 minutes to obtain a dough, which was extruded through a die into a cylindrical strip with a diameter of 1.7 mm and a length of 2 mm. Catalyst F was obtained after drying at 120°C for 6 h and calcining at 550°C in air atmosphere for 4 h, as shown in Table 1 for details.

[0095] Example 7

[0096] 80 g of the Beta / ZSM-12 symbiotic molecular sieve of Preparation Example 5 (SiO2 / Al2O3 molar ratio of 20, average grain size of 300 nm, Beta to ZSM-12 symbiotic ratio of 2:1), 5 g of TiO2 powder, 15 g of alumina, and 2.5 g of sesbania powder were mixed evenly in a kneader, 45 g of an aqueous solution containing 1 g of nitric acid was slowly added to the kneader, and the mixture was kneaded for 30 minutes to obtain a dough, which was extruded through a die into a cylindrical strip with a diameter of 1.7 mm and a length of 2 mm. Catalyst G was obtained after drying at 120°C for 6 h and calcining at 550°C in air atmosphere for 4 h, as shown in Table 1 for details.

[0097] Example 8

[0098] 80 g of the Beta / ZSM-12 symbiotic molecular sieve of Preparation Example 6 (SiO2 / Al2O3 molar ratio of 10, average grain size of 150 nm, Beta to ZSM-12 symbiotic ratio of 2:1), 5 g of TiO2 powder, 15 g of alumina, and 2.5 g of sesbania powder were mixed evenly in a kneader, 45 g of an aqueous solution containing 1 g of nitric acid was slowly added to the kneader, and the mixture was kneaded for 30 minutes to obtain a dough, which was extruded through a die into a cylindrical strip with a diameter of 1.7 mm and a length of 2 mm. Catalyst H was obtained after drying at 120°C for 6 h and calcining at 550°C in air atmosphere for 4 h, as shown in Table 1.

[0099] Example 9

[0100] 74 g of the Beta / ZSM-12 symbiotic molecular sieve of Preparation Example 7 (SiO2 / Al2O3 molar ratio of 15, average grain size of 150 nm, Beta to ZSM-12 symbiotic ratio of 1:1), 6 g of TiO2 powder, 20 g of silica sol, and 2.5 g of sesbania powder were mixed evenly in a kneader, 45 g of aqueous solution was slowly added to the kneader, and kneaded for 30 minutes to obtain a dough, which was extruded through a die into a cylindrical strip with a diameter of 1.7 mm and a length of 2 mm. Catalyst I was obtained after drying at 120°C for 6 h and calcining at 550°C in air atmosphere for 4 h, as shown in Table 1 for details.

[0101] Example 10

[0102] The catalyst was prepared in the same manner as in Example 3, except that the Beta / ZSM-12 symbiotic molecular sieve of Preparation Example 8 (SiO2 / Al2O3 molar ratio of 30, average grain size of 300 nm, Beta to ZSM-12 symbiotic ratio of 2:1) was used to replace the symbiotic molecular sieve of Preparation Example 1 of equal mass to obtain Catalyst J, as shown in Table 1 for details.

[0103] Embodiment 11

[0104] The catalyst was prepared in the same manner as in Example 3, except that the content of Beta / ZSM-12 intergrowth molecular sieve was changed to 70%, to obtain catalyst K, as shown in Table 1.

[0105] Example 12

[0106] The catalyst was prepared in the same manner as in Example 3, except that the Beta / ZSM-12 symbiotic molecular sieve of Preparation Example 9 (SiO2 / Al2O3 molar ratio of 10, average grain size of 500 nm, Beta to ZSM-12 symbiotic ratio of 2:1) was used to replace the symbiotic molecular sieve of Preparation Example 1 of equal mass to obtain Catalyst L, as shown in Table 1 for details.

[0107] Comparative Example 1

[0108] 51.3 g of Beta molecular sieve on a dry basis, 25.7 g of ZSM-12 molecular sieve on a dry basis (the SiO2 / Al2O3 molar ratio of the two molecular sieves is 10-12, and the average grain size is 300 nm), 8 g of TiO2 powder on a dry basis, 15 g of alumina on a dry basis, and 2.5 g of sesbania powder on a dry basis are mixed uniformly in a kneader, 45 g of an aqueous solution containing 1 g of nitric acid is slowly added to the kneader, and the mixture is kneaded for 30 minutes to obtain a dough-like substance, which is then extruded through a die into cylindrical strips with a diameter of 1.7 mm and a length of 2 mm, and the catalyst is obtained after drying at 120°C for 6 h and calcining at 550°C in air atmosphere for 4 h, as shown in Table 1 for details.

[0109] Comparative Example 2

[0110] 83.7 g of dry basis Beta / ZSM-12 symbiotic molecular sieve (SiO2 / Al2O3 molar ratio of 10, average crystallite size of 300 nm, Beta to ZSM-12 symbiotic ratio of 2:1), 16.3 g of dry basis alumina, and 2.5 g of sesbania powder were mixed evenly in a kneader, 45 g of an aqueous solution containing 1 g of nitric acid was slowly added to the kneader, and kneaded for 30 minutes to obtain a dough, which was extruded through a die into a cylindrical strip with a diameter of 1.7 mm and a length of 2 mm, and the catalyst was obtained after drying at 120°C for 6 h and calcining at 550°C in air atmosphere for 4 h, as shown in Table 1 for details.

[0111] Comparative Example 3

[0112] The catalyst was prepared by following the method of Example 3, except that titanium dioxide was replaced by zinc oxide of the same mass, as shown in Table 1.

[0113] Table 1

[0114]

[0115] Test Case

[0116] The catalysts prepared in the examples and comparative examples were respectively loaded into a fixed bed reactor and heated at a temperature of 280°C, a pressure of 3.5 MPa, and a mass space velocity of 1.5 h -1 , liquid phase transalkylation reaction was carried out under hydrogen atmosphere conditions. The raw material composition is shown in Table 2, and the reaction results are shown in Table 3.

[0117] Table 2

[0118] Components Toluene C9 aromatics C10 Aromatics Weight content, % 50 45 5

[0119] Table 3

[0120] catalyst Aromatic conversion rate, % Xylene selectivity, % A 49.2 83.3 B 51.0 81.0 C 50.6 85.2 D 48.3 82.2 E 50.5 83.6 F 48.5 83.1 G 49.1 84.8 H 51.8 85.3 I 48.0 84.6 J 47.9 80.5 K 47.2 82.3 L 49.0 84.2 Comparative Example 1 30.6 55.9 Comparative Example 2 35.1 63.3 Comparative Example 3 34.4 77.3

[0121] The catalysts prepared in the examples and comparative examples were respectively loaded into a fixed bed reactor and heated at a temperature of 295°C, a pressure of 4.0 MPa, and a mass space velocity of 1.0 h-1 , liquid phase transalkylation reaction was carried out under hydrogen atmosphere conditions. The raw material composition is shown in Table 2, and the reaction results are listed in Table 4.

[0122] Table 4

[0123]

[0124]

[0125] It can be seen from the results of Table 3 and Table 4 that the use of the transalkylation catalyst provided by the present invention, the Beta / ZSM-12 symbiotic molecular sieve and TiO2 in combination, under liquid phase reaction conditions, has a higher aromatic conversion rate and also a higher xylene selectivity, and can be used in the industrial production of paraxylene to achieve the purpose of increasing the production of xylene.

[0126] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A transalkylation catalyst, characterized in that: The catalyst comprises Beta / ZSM-12 intergrowth molecular sieve, titanium dioxide and a binder.

2. The catalyst according to claim 1, wherein Based on the total amount of catalyst, the weight percentage of the Beta / ZSM-12 intergrowth molecular sieve is 67-88%, preferably 74-85%; the weight percentage of titanium dioxide is 2-8%, preferably 3-6%; the weight percentage of the binder is 10-25%, preferably 10-20%.

3. The catalyst according to claim 1 or 2, wherein The SiO2 / Al2O3 molar ratio of the Beta / ZSM-12 intergrowth molecular sieve is 10-40, preferably 10-20; And / or, the average crystal size of the Beta / ZSM-12 intergrowth molecular sieve is less than 500 nm, preferably 100-300 nm; And / or, in the Beta / ZSM-12 symbiotic molecular sieve, the symbiotic ratio of Beta molecular sieve to ZSM-12 molecular sieve is 0.25-4:1, preferably 0.5-2:

1.

4. The catalyst according to any one of claims 1 to 3, wherein The binder is silicon oxide and / or aluminum oxide.

5. A method for preparing the transalkylation catalyst according to any one of claims 1 to 4, the method comprising the following steps: (1) mixing Beta / ZSM-12 intergrowth molecular sieve, titanium dioxide, a binder, and optionally an extrusion aid and a peptizing agent in the presence of a solvent; (2) The mixed material obtained in step (1) is molded, and then dried and calcined.

6. The preparation method according to claim 5, wherein: The extrusion aid is selected from at least one of sesbania powder, methylcellulose, hydroxypropyl methylcellulose and dextrin; Preferably, the amount of the extrusion aid is 1-5%, preferably 1-3%, of the total weight of the Beta / ZSM-12 intergrowth molecular sieve, titanium dioxide and binder on a dry basis; Preferably, the peptizing agent is nitric acid; Preferably, the peptizing agent is used in an amount of 2-8% by weight of the binder on a dry basis.

7. The preparation method according to claim 5, wherein: The drying conditions include: temperature of 60-150°C and time of 3-12h; And / or, the calcination conditions include: temperature of 450-650° C., preferably 500-600° C.; time of 2-10 h, preferably 3-8 h.

8. Use of the transalkylation catalyst according to any one of claims 1 to 4 in liquid phase transalkylation of aromatic hydrocarbons.

9. A method for liquid phase transalkylation of aromatic hydrocarbons, the method comprising: In the presence of hydrogen and under liquid phase reaction conditions, a mixture containing toluene and C9+ aromatic hydrocarbons is contacted with a catalyst for reaction, wherein the catalyst is selected from the transalkylation catalyst described in any one of claims 1 to 4.

10. The method according to claim 9, wherein: The liquid phase reaction conditions include: temperature of 200-350°C, preferably 250-300°C; pressure of 2-5MPa, preferably 3-4MPa; mass space velocity of 0.5-2.5h -1 , preferably 1-2h -1 .

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