Transalkylation catalysts and methods for making same, methods for making 2,6-dimethylnaphthalene

Abstract

The application relates to the technical field of catalysts, and discloses an alkyl transfer catalyst, a preparation method of the alkyl transfer catalyst, and a method for preparing 2,6-dimethylnaphthalene, the catalyst comprising a carrier and an active metal component loaded on the carrier; wherein the carrier comprises a 12-membered ring molecular sieve and a binder; the active metal component is selected from at least one of transition metals; the acid amount of B acid in the catalyst is 100-400 mu mol / g, and the ratio of the acid amount of B acid to the acid amount of L acid is 1-3:1. The catalyst is used in an alkyl transfer reaction for preparing 2,6-dimethylnaphthalene, so that the reaction of naphthalene, methylnaphthalene and monocyclic aromatic hydrocarbons with methyl can not only have a high naphthalene / methylnaphthalene conversion rate, but also can have a high 2,6-dimethylnaphthalene selectivity and yield, and the molecular sieve catalyst can be regenerated and used for multiple times, and has good stability.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to an alkyl transfer catalyst and its preparation method, and a method for preparing 2,6-dimethylnaphthalene. Background Technology

[0002] Polyethylene naphthalate (PEN) is a novel polyester material that, compared to traditional polyethylene terephthalate (PET), exhibits higher mechanical strength, heat resistance, chemical stability, gas barrier properties, and resistance to ultraviolet radiation. It is suitable for industrial applications with higher material requirements, such as electronic devices, packaging materials, instrumentation, and aerospace. The main production route for PEN is the oxidation of 2,6-dimethylnaphthalene to produce naphthalic acid, followed by the polymerization of naphthalic acid with ethylene glycol.

[0003] Currently, the only industrialized production route for 2,6-dimethylnaphthalene is the side-chain alkylation reaction of o-xylene with butadiene by BP Amoco, followed by cyclization and dehydrogenation aromatization to obtain 1,5-dimethylnaphthalene. The 1,5-dimethylnaphthalene isomerizes to obtain the dimethylnaphthalene isomer, which is then separated and purified to obtain 2,6-dimethylnaphthalene with a purity of over 95 wt%. This technology is complex and costly, hindering the large-scale application and development of PEN.

[0004] 2,6-Dimethylnaphthalene can be synthesized in one step via alkylation using naphthalene or methylnaphthalene as raw materials. This process is simple, and the raw materials are abundant, making it a highly promising low-cost route for the production of 2,6-dimethylnaphthalene. US5670704 discloses a transfer alkylation reaction of 2-methylnaphthalene using AlCl3 as a catalyst, mesitylene, pentamethylbenzene, and hexamethylbenzene as transfer alkylating agents, and haloalkanes as solvents at 40°C. Experimental results show that the yield of 2,6-dimethylnaphthalene can reach 28.74%. However, since the AlCl3 catalyst cannot be reused, the separation of the catalyst from the product can cause corrosion to the equipment, and acidic wastewater is also generated, making the waste treatment process complex.

[0005] CN101391937A discloses a method for preparing 2,6-dimethylnaphthalene using ionic liquid catalysis. The method employs either a haloalkylimidazolium salt ionic liquid or a haloalkylpyridine ionic liquid as a catalyst. Methylnaphthalene, a transfer alkylating agent, and a solvent are mixed, and the ionic liquid is added. The mixture is reacted at 10-50°C for 0.5-8 h under inert gas protection, and then 2,6-dimethylnaphthalene is obtained by separation. However, when the selectivity for 2,6-dimethylnaphthalene reaches 100%, the conversion rate of methylnaphthalene is generally lower than 13%, resulting in a low yield of 2,6-dimethylnaphthalene.

[0006] CN108341734A reports a method for preparing 2,6-dimethylnaphthalene using magnetic ionic liquid catalysis. The method utilizes an ultrasonic reactor to carry out alkyl transfer reactions using 1-methylnaphthalene, 2-methylnaphthalene, and mesitylene as raw materials. The yield of 2,6-dimethylnaphthalene can reach 37%. However, the reactor reaction has low efficiency and the catalyst separation and recovery are difficult.

[0007] CN1762932A discloses a method for generating 2,6-dimethylnaphthalene from 2-methylnaphthalene by alkyl transfer reaction with trimethylbenzene, tetramethylbenzene, and pentamethylbenzene under supercritical reaction conditions using modified molecular sieve as a catalyst. The reaction results show that the conversion rate of 2-methylnaphthalene is 52%, but the selectivity of 2,6-dimethylnaphthalene is low, and the reaction temperature and pressure are high, resulting in high energy consumption.

[0008] In summary, existing methods for preparing 2,6-dimethylnaphthalene via alkyl transfer all suffer from problems related to energy consumption, yield, and stability, which limit the industrialization of alkyl transfer methods for preparing 2,6-dimethylnaphthalene. Summary of the Invention

[0009] The purpose of this invention is to overcome the problems of high energy consumption and low yield in the preparation of 2,6-dimethylnaphthalene by alkyl transfer in the prior art, and to provide an alkyl transfer catalyst and its preparation method, as well as a method for preparing 2,6-dimethylnaphthalene. This catalyst has excellent low-temperature activity, high reactant conversion rate, and good product selectivity when used in the catalytic alkyl transfer reaction to prepare 2,6-dimethylnaphthalene.

[0010] To achieve the above objectives, the present invention provides an alkyl transfer catalyst, the catalyst comprising a support and an active metal component supported on the support; wherein the support comprises a twelve-membered ring molecular sieve and a binder; and the active metal component is selected from at least one transition metal.

[0011] The catalyst contains 100-400 μmol / g of Brønsted acid and the ratio of Brønsted acid to L-acid is 1-3:1.

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

[0013] (1) The twelve-membered ring molecular sieve is mixed with the binder precursor, and then molded and dried to obtain the carrier precursor;

[0014] (2) The carrier precursor is heat-treated by contacting it with acid, and then subjected to a first drying and a first calcination.

[0015] (3) In the presence of ultrasound, the product of the first calcination is impregnated with a solution containing an active metal component precursor, and then subjected to a second drying and a second calcination.

[0016] The active metal component is selected from at least one transition metal, preferably at least one of Cu, Fe and Zn.

[0017] A third aspect of the present invention provides a method for preparing 2,6-dimethylnaphthalene, the method comprising: contacting a reactant with a transfer alkylating agent under liquid phase conditions in the presence of a catalyst;

[0018] The reactants are selected from at least one of naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene; the transfer alkylating agent is a methyl-substituted monocyclic aromatic hydrocarbon.

[0019] The catalyst is the alkyl transfer catalyst provided in the first aspect.

[0020] The alkyl transfer catalyst provided by this invention employs a transition metal supported on a twelve-membered ring molecular sieve. The unique pore structure of the twelve-membered ring molecular sieve, combined with suitable Brønsted and Lewis acid contents, synergistically enables the reaction of naphthalene, methylnaphthalene, and monocyclic aromatic hydrocarbons containing methyl groups to achieve not only high naphthalene / methylnaphthalene conversion rates but also high selectivity and yield of 2,6-dimethylnaphthalene. The molecular sieve catalyst can be regenerated multiple times and exhibits good stability. Further controlling the catalyst to have suitable pore number and size can further improve its low-temperature activity, conversion rate, and selectivity.

[0021] The method for preparing 2,6-dimethylnaphthalene provided by this invention can be carried out under mild liquid phase conditions, with low energy consumption, simple raw materials, and a multiphase continuous reaction. It is applicable to fixed beds, simple to operate, and suitable for industrial promotion. In preferred cases, no additional solvent is required in the reaction process, and the catalyst can be repeatedly regenerated and reused, which helps to improve the economy of the reaction process and reduce costs. Detailed Implementation

[0022] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] A first aspect of the present invention provides an alkyl transfer catalyst, the catalyst comprising a support and an active metal component supported on the support; wherein the support comprises a twelve-membered ring molecular sieve and a binder; and the active metal component is selected from at least one transition metal.

[0024] The catalyst contains 100-400 μmol / g of Brønsted acid and the ratio of Brønsted acid to L-acid is 1-3:1.

[0025] The inventors of this invention discovered in their research that by using a carrier containing a twelve-membered ring molecular sieve to load transition metals, the special pore structure of the twelve-membered ring molecular sieve, combined with the appropriate content of Brønsted acid and Lewis acid, can be used in the alkyl transfer reaction to prepare 2,6-dimethylnaphthalene. This results in a reaction between naphthalene, methylnaphthalene, and monocyclic aromatic hydrocarbons with methyl groups, which not only achieves a high naphthalene / methylnaphthalene conversion rate but also a high selectivity and yield for 2,6-dimethylnaphthalene.

[0026] According to some preferred embodiments of the present invention, the amount of Brønsted acid in the catalyst is 150-350 μmol / g, more preferably 180-250 μmol / g.

[0027] According to some preferred embodiments of the present invention, in the catalyst, the ratio of Brønsted acid to Lewis acid is 1.2-3:1, for example, typical but not limiting ratios or ranges between 1.2:1, 1.5:1, 1.8:1, 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, etc. Preferably, in the catalyst, the ratio of Brønsted acid to Lewis acid is 2-2.8:1. In the above preferred embodiments, it is beneficial to further improve the low-temperature activity of the catalyst and improve product selectivity and yield.

[0028] In this invention, the contents of Brønsted acid and Lewis acid in the catalyst are determined by pyridine probe infrared spectroscopy.

[0029] According to the present invention, preferably, the catalyst has a specific surface area of ​​250-700 m². 2 / g, preferably 300-650m 2 / g.

[0030] According to the present invention, preferably, the pore volume of the catalyst is 0.28-0.7 mL / g, more preferably 0.3-0.68 mL / g.

[0031] In this invention, the specific surface area and pore volume of the catalyst are obtained by BET full analysis method.

[0032] The present invention allows for a wide selection range of the twelve-membered ring molecular sieve, for example, it can be at least one of Y-type molecular sieve, Beta-type molecular sieve, MCM-22 molecular sieve, MCM-56 molecular sieve, SAPO-5 molecular sieve, SAPO-37 molecular sieve, and SAPO-40 molecular sieve. More preferably, the twelve-membered ring molecular sieve is selected from at least one of Y-type molecular sieve, Beta-type molecular sieve, and SAPO-5 molecular sieve. Using the above-mentioned preferred molecular sieve types facilitates the diffusion of reactants into the pores and their contact with the acid centers, thereby further improving the catalytic activity of the catalyst and increasing the yield of the target product.

[0033] According to the present invention, preferably, the molar ratio of silica to alumina in the twelve-membered ring molecular sieve is 0.1-30, more preferably 0.8-25. In the present invention, the molar ratio of silica to alumina in the twelve-membered ring molecular sieve is obtained by X-ray fluorescence spectrometry (XRF).

[0034] This invention does not particularly limit the type of binder in the support; any binder conventionally used in catalyst supports in the art can be applied to this invention, such as at least one of alumina, kaolin, attapulgite, bentonite, diatomaceous earth, and silica. Preferably, the binder is alumina to further improve the catalytic activity and strength of the catalyst.

[0035] According to some preferred embodiments of the present invention, based on the total amount of the carrier, the content of the twelve-membered ring molecular sieve is 60-80 wt%, preferably 65-75 wt%; and the content of the binder is 20-40 wt%, preferably 25-35 wt%.

[0036] According to the present invention, the active metal component in the catalyst is selected from at least one transition metal, such as at least one selected from Cu, Zn, Ag, Ni, Co, Fe, Mn, Cr, Mo, Ru, Rh, Pd, and Pt, preferably at least one selected from Cu, Fe, and Zn, and more preferably Cu and / or Fe. Using the above-mentioned preferred active metal composition helps to further modulate the acidity of the molecular sieve, thereby improving the catalytic activity and selectivity of the catalyst.

[0037] According to the present invention, preferably, based on the total amount of the catalyst, the content of the support is 90-99.9 wt%, more preferably 92-99 wt%, and the content of the active metal component, calculated as an element, is 0.1-10 wt%, more preferably 1-8 wt%. In the above-mentioned preferred cases, it is advantageous to obtain the desired acidity and pore distribution.

[0038] In this invention, the content of each component in the catalyst is obtained by X-ray fluorescence spectroscopy (XRF).

[0039] A second aspect of the present invention provides a method for preparing the above-mentioned alkyl transfer catalyst, comprising:

[0040] (1) The twelve-membered ring molecular sieve is mixed with the binder precursor, and then molded and dried to obtain the carrier precursor;

[0041] (2) The carrier precursor is heat-treated by contacting it with acid, and then subjected to a first drying and a first calcination;

[0042] (3) In the presence of ultrasound, the product of the first calcination is impregnated with a solution containing an active metal component precursor, and then subjected to a second drying and a second calcination.

[0043] The active metal component is selected from at least one transition metal, preferably at least one of Cu, Fe and Zn.

[0044] In this invention, the twelve-membered ring molecular sieve has the same definition as described above, and will not be repeated here. Preferably, the twelve-membered ring molecular sieve is a hydrogen-form twelve-membered ring molecular sieve.

[0045] Preferably, the specific surface area of ​​the twelve-membered ring molecular sieve is 280-740 m². 2 / g, preferably 340-730m 2 / g.

[0046] Preferably, the pore volume of the hydrogen-type twelve-membered ring molecular sieve is 0.26-0.66 mL / g, and more preferably 0.28-0.64 mL / g.

[0047] In this invention, the binder precursor refers to any substance that can be obtained by calcination, which is well known to those skilled in the art. For example, the precursor of alumina can be boehmite.

[0048] According to some preferred embodiments of the present invention, the dry basis mass ratio of the twelve-membered ring molecular sieve to the binder precursor is 60-80:20-40, preferably 65-75:25-35.

[0049] The present invention does not particularly limit the molding method, and those skilled in the art can choose according to actual needs, such as extrusion molding.

[0050] A solvent may also be introduced during the molding process. According to some preferred embodiments of the present invention, step (1) includes: mixing a twelve-membered ring molecular sieve, a binder precursor, and a solvent, followed by molding and drying to obtain a carrier precursor. The present invention does not have particular requirements regarding the specific type of the solvent; preferably, the solvent is an aqueous solution of an acid, preferably selected from at least one of nitric acid, acetic acid, citric acid, oxalic acid, and formic acid. Preferably, the concentration of the acid in the solvent is 1-5 wt%.

[0051] Preferably, the mass ratio of the adhesive solvent to the total mass of the twelve-membered ring molecular sieve and the binder precursor is 0.2-0.6:1.

[0052] According to some preferred embodiments of the present invention, the drying conditions in step (1) include: a temperature of 30-200°C, preferably 60-180°C; and a time of 0.1-72h, preferably 4-48h.

[0053] In this invention, preferably, the molding process does not include a baking process.

[0054] In this invention, the appropriate content of Brønsted acid and Lewis acid in the catalyst is adjusted by the heat treatment described in step (2) and the loading of active metal components in step (3), and the catalyst is further adjusted to have an appropriate number and size of pores.

[0055] According to some preferred embodiments of the present invention, in step (2), the acid solution is provided by an aqueous solution of acid, the concentration of which is 0.5-3 mol / L, preferably 0.5-2.5 mol / L.

[0056] The present invention has a wide range of choices for the types of acids, and can use conventional organic acids and / or inorganic acids in the art. Preferably, the acid is selected from at least one of citric acid, ethylenediaminetetraacetic acid, malic acid, tartaric acid, sulfuric acid, phosphoric acid and nitric acid, and is preferably citric acid and / or phosphoric acid.

[0057] Preferably, the amount of acid solution used is 5-15 mL, more preferably 8-12 mL, relative to 1 g of the carrier precursor.

[0058] According to some preferred embodiments of the present invention, the heat treatment temperature is 40-100℃, preferably 60-90℃, and the time is 5-24h, preferably 6-18h. Using the above preferred embodiments is beneficial for further optimizing the acid distribution of the catalyst and improving the catalytic activity and selectivity of the catalyst.

[0059] According to some preferred embodiments of the present invention, the temperature of the first drying is 30-200°C, preferably 60-180°C, and the time is 0.1-72h, preferably 4-48h.

[0060] According to some preferred embodiments of the present invention, the temperature of the first calcination is 380-580°C, preferably 400-520°C, and the time is 0.5-20h, preferably 3-12h.

[0061] In this invention, the impregnation in step (3) is carried out in the presence of ultrasound. The product of the first calcination can be impregnated in a solution containing an active metal component precursor, and then the ultrasound treatment can be turned on.

[0062] This invention allows for a wide range of selection for the active metal component precursor, and can employ soluble compounds of active metal components commonly used in the art, such as nitrates and / or chlorides of transition metals. This invention also does not impose particular requirements on the concentration and amount of the solution containing the active metal component precursor, as long as the required amount of transition metal is met. Preferably, the concentration of the solution containing the active metal component precursor is 0.1-1 mol / L.

[0063] According to some preferred embodiments of the present invention, the ultrasonic conditions include: an ultrasonic power density of 0.1-20 W / cm². 2 Preferably 5-15W / cm 2 The preferred embodiments described above facilitate the uniform dispersion of the active metal components.

[0064] According to the present invention, preferably, the impregnation temperature is 40-100°C, more preferably 60-90°C; and the time is 5-24h, more preferably 6-18h.

[0065] The present invention does not particularly limit the conditions for the second drying, as long as excess impregnation liquid can be removed. Preferably, the temperature for the second drying is 30-200°C, and the time is 0.1-72 hours.

[0066] Preferably, the second calcination temperature is 400-600℃ and the time is 0.5-20h.

[0067] According to the present invention, preferably, the second drying and the second calcination are carried out under an inert atmosphere, which may be provided by nitrogen.

[0068] A third aspect of the present invention provides a method for preparing 2,6-dimethylnaphthalene, the method comprising: contacting a reactant with a transfer alkylating agent under liquid phase conditions in the presence of a catalyst;

[0069] The reactants are selected from at least one of naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene; the transfer alkylating agent is a methyl-substituted monocyclic aromatic hydrocarbon.

[0070] The catalyst is the alkyl transfer catalyst described in the first aspect.

[0071] According to the present invention, preferably, the transfer alkylating agent is selected from any one or a mixture of several of toluene, xylene, trimethylbenzene, and tetramethylbenzene. The xylene may be at least one of o-xylene, p-xylene, and m-xylene; the trimethylbenzene may be at least one of pseudotrimethylbenzene, ternarytrimethylbenzene, and mesitylene; and the tetramethylbenzene may be at least one of pseudotetramethylbenzene, ternarytetramethylbenzene, and mesitylene.

[0072] This invention does not have particular requirements regarding the source of the transfer alkylating agent, which can also be provided by mixed C8 aromatics, mixed C9 aromatics, mixed C10 aromatics, etc. The mixed C8, mixed C9, and mixed C10 aromatics have conventional definitions in the art; mixed C8 aromatics include xylene and ethylbenzene; mixed C9 aromatics include trimethylbenzene, methyl ethylbenzene, and propylbenzene; and mixed C10 aromatics include tetramethylbenzene, diethylbenzene, and methylpropylbenzene, etc. Preferably, the methyl-substituted aromatics (i.e., xylene, trimethylbenzene, or tetramethylbenzene) in the mixed C8, mixed C9, and mixed C10 aromatics each account for approximately 40-60 mol%.

[0073] In this invention, the molar ratio of toluene, xylene, trimethylbenzene and tetramethylbenzene in the transfer alkylating agent is (0-10):(0-10):(0-10):(0-10).

[0074] According to some preferred embodiments of the present invention, the molar ratio of the reactant to the transfer alkylating agent is 1:(1-10), preferably 1:(2-7).

[0075] According to the present invention, the method for preparing 2,6-dimethylnaphthalene can be carried out under mild liquid phase conditions and at a reaction temperature not exceeding 400°C, and has high raw material conversion rate and product selectivity, resulting in a high yield of 2,6-dimethylnaphthalene.

[0076] According to some preferred embodiments of the present invention, the liquid phase conditions include: a reaction temperature of 150-400°C, preferably 250-350°C; a reaction pressure of 0.5-5 MPa, preferably 2.0-4.0 MPa; and a weight hourly space velocity (WHSV) of 0.1-5 h⁻¹ for the reactants. -1 Preferably 0.5-3h -1 In this invention, unless otherwise specified, all pressures refer to gauge pressure. By employing the preferred embodiments described above, while ensuring high raw material conversion rates and product selectivity, reaction energy consumption can be further reduced, and the economic efficiency of the reaction process can be improved.

[0077] The present invention will be described in detail below through embodiments.

[0078] Unless otherwise specified, the raw materials used in the following examples and comparative examples are all commercially available.

[0079] Example 1

[0080] (1) Take H-Beta molecular sieve with a silica / alumina molar ratio of 25 (specific surface area of ​​693 m²) 2 The mixture of 0.56 mL / g (with a pore volume of 0.56 mL / g) and pseudoboehmite (produced by Condea, Germany, brand name Pural SB powder) at a dry basis mass ratio of 65:35 was prepared. Dilute nitric acid with a mass ratio of 1:2 was added to the mixture and kneaded. The mixture was then extruded and dried at 110°C for 4 hours to obtain the carrier precursor.

[0081] (2) The carrier precursor was placed in a citric acid solution with a concentration of 1 mol / L. The amount of acid solution was 10 mL relative to 1 g of the carrier precursor. The solution was treated at 80 °C for 8 h, then dried at 110 °C for 4 h, and calcined at 520 °C for 5 h.

[0082] (3) The sample treated in step (2) was immersed in a 0.2 mol / L Cu(NO3)2 solution, and the immersion solution was subjected to ultrasonic treatment with an ultrasonic power density of 10 W / cm². 2 The processing time is 6 hours and the temperature is 60℃.

[0083] (4) The sample treated in step (3) was dried at 110°C for 4 hours under a nitrogen atmosphere and calcined at 560°C for 5 hours to obtain catalyst A1. X-ray fluorescence spectroscopy (XRF) analysis showed that the Cu content in the catalyst was 2.13% by mass.

[0084] The acid composition, specific surface area, and pore volume of the catalyst are shown in Table 1.

[0085] Example 2

[0086] The method is the same as in Example 1, except that HY molecular sieve with a silica / alumina molar ratio of 7 (specific surface area of ​​730 m²) is used. 2 The catalyst A2 was obtained by replacing H-Beta molecular sieves with a pore volume of 0.33 mL / g. X-ray fluorescence spectroscopy (XRF) analysis showed that the Cu content in the catalyst was 2.42% by mass. The acid composition, specific surface area, and pore volume of the catalyst are shown in Table 1.

[0087] Example 3

[0088] (1) Take H-Beta molecular sieve with a silica / alumina molar ratio of 25 (specific surface area of ​​693 m²) 2The mixture of 0.56 mL / g (with a pore volume of 0.56 mL / g) and pseudoboehmite (produced by Condea, Germany, brand name Pural SB powder) at a dry basis mass ratio of 70:30 was prepared. Dilute nitric acid with a mass ratio of 1:2 was added to the mixture and kneaded. The mixture was then extruded into strips and dried at 110°C for 4 hours to obtain the carrier precursor.

[0089] (2) The carrier precursor was placed in a 2 mol / L phosphoric acid solution, and the amount of acid solution was 10 mL relative to 1 g of the carrier precursor. The solution was treated at 80 °C for 8 h, then dried at 110 °C for 4 h, and calcined at 520 °C for 5 h.

[0090] (3) The sample treated in step (2) was immersed in a 0.2 mol / L Cu(NO3)2 solution, and the immersion solution was subjected to ultrasonic treatment with an ultrasonic power density of 10 W / cm². 2 The processing time is 6 hours and the temperature is 60℃.

[0091] (4) The sample treated in step (3) was dried at 110°C for 4 hours under a nitrogen atmosphere and calcined at 560°C for 5 hours to obtain catalyst A3. X-ray fluorescence spectroscopy (XRF) analysis showed that the Cu content in the catalyst was 2.16% by mass.

[0092] The acid composition, specific surface area, and pore volume of the catalyst are shown in Table 1.

[0093] Example 4

[0094] (1) Take H-Beta molecular sieve with a silica / alumina molar ratio of 25 (specific surface area of ​​693 m²) 2 The mixture of 0.56 mL / g (with a pore volume of 0.56 mL / g) and pseudoboehmite (produced by Condea, Germany, brand name Pural SB powder) at a dry basis mass ratio of 65:35 was prepared. Dilute nitric acid with a mass ratio of 1:2 was added to the mixture and kneaded. The mixture was then extruded and dried at 110°C for 4 hours to obtain the carrier precursor.

[0095] (2) The carrier precursor was placed in a citric acid solution with a concentration of 2 mol / L. The amount of acid solution was 10 mL relative to 1 g of the carrier precursor. The solution was treated at 80 °C for 8 h, then dried at 110 °C for 4 h, and calcined at 520 °C for 5 h.

[0096] (3) The sample treated in step (2) was immersed in a 0.2 mol / L Fe(NO3)3 solution, and the immersion solution was subjected to ultrasonic treatment with an ultrasonic power density of 10 W / cm³. 2 The processing time is 6 hours and the temperature is 60℃.

[0097] (4) The sample treated in step (3) was dried at 110°C for 4 hours under a nitrogen atmosphere and calcined at 560°C for 5 hours to obtain catalyst A4. X-ray fluorescence spectroscopy (XRF) analysis showed that the Cu content in the catalyst was 1.88% by mass.

[0098] The acid composition, specific surface area, and pore volume of the catalyst are shown in Table 1.

[0099] Example 5

[0100] (1) Take HY molecular sieve with a silica / alumina molar ratio of 7 (specific surface area of ​​604 m²) 2 The mixture of 0.32 mL / g (with a pore volume of 0.32 mL / g) and pseudoboehmite (produced by Condea, Germany, brand name Pural SB powder) at a dry basis mass ratio of 65:35 was prepared. Dilute nitric acid with a mass ratio of 1% by mass was added to the mixture and kneaded. The mixture was then extruded into strips and dried at 110°C for 4 hours to obtain the carrier precursor.

[0101] (2) The carrier precursor was placed in a citric acid solution with a concentration of 1 mol / L. The amount of acid solution was 10 mL relative to 1 g of the carrier precursor. The solution was treated at 80 °C for 8 h, then dried at 110 °C for 4 h, and calcined at 520 °C for 5 h.

[0102] (3) The sample treated in step (2) was impregnated in a 0.2 mol / L Fe(NO3)3 solution, and the impregnation solution was subjected to ultrasonic treatment with an ultrasonic power density of 5 W / cm². 2 The processing time is 6 hours and the temperature is 60℃.

[0103] (4) The sample treated in step (3) was dried at 110°C for 4 hours under a nitrogen atmosphere and calcined at 560°C for 5 hours to obtain catalyst A5. X-ray fluorescence spectroscopy (XRF) analysis showed that the Fe element content in the catalyst was 1.93% by mass.

[0104] The acid composition, specific surface area, and pore volume of the catalyst are shown in Table 1.

[0105] Example 6

[0106] The method is the same as in Example 1, except that SAPO-5 molecular sieve with a silica / alumina molar ratio of 0.5 (specific surface area of ​​593 m²) is used. 2 The catalyst obtained by replacing H-Beta molecular sieves with a pore volume of 0.28 mL / g (with a pore volume of 0.28 mL / g) is designated A6. X-ray fluorescence spectroscopy (XRF) analysis showed that the Cu content in the catalyst was 1.42% by mass.

[0107] Comparative Example 1

[0108] The method is the same as in Example 1, except that HZSM-5 molecular sieve with a silica / alumina molar ratio of 25 (specific surface area of ​​370 m²) is used. 2 The catalyst obtained by replacing H-Beta molecular sieves with a pore volume of 0.20 mL / g was designated DA1. X-ray fluorescence spectroscopy (XRF) analysis showed that the Cu content in the catalyst was 2.42% by mass. The acid composition, specific surface area, and pore volume of the catalyst are shown in Table 1.

[0109] Comparative Example 2

[0110] The method is the same as in Example 1, except that the acid treatment in step (2) is not performed. The carrier precursor is dried at 110°C for 4 hours, calcined at 520°C for 5 hours, and then impregnated in a 0.2 mol / L Cu(NO3)2 solution. The impregnation solution is then subjected to ultrasonic treatment with an ultrasonic power density of 5 W / cm². 2 The processing time is 6 hours and the temperature is 60℃.

[0111] The treated sample was then dried at 110°C for 4 hours under a nitrogen atmosphere and calcined at 560°C for 5 hours to obtain catalyst DA2. X-ray fluorescence spectroscopy (XRF) analysis showed that the Cu content in the catalyst was 2.32% by mass. The acid composition, specific surface area, and pore volume of the catalyst are shown in Table 1.

[0112] Comparative Example 3

[0113] (1) Take H-Beta molecular sieve with a silica / alumina molar ratio of 27 (specific surface area of ​​439 m²) 2 The mixture of 0.50 mL / g (with a pore volume of 0.50 mL / g) and pseudoboehmite (produced by Condea, Germany, brand name Pural SB powder) at a dry basis mass ratio of 65:35 was prepared. Dilute nitric acid with a concentration of 1% by mass was added to the mixture at a mass ratio of 1:2, and the mixture was kneaded, extruded into strips, and then dried at 110°C for 4 hours to obtain the carrier precursor.

[0114] (2) The support precursor was placed in a 1 mol / L citric acid solution, with 10 mL of acid solution relative to 1 g of the support precursor. The solution was treated at 80 °C for 8 h, then dried at 110 °C for 4 h, and calcined at 520 °C for 5 h. Catalyst DA3 was obtained. The acid composition, specific surface area, and pore volume of the catalyst are shown in Table 1.

[0115] Table 1

[0116]

[0117] Test case

[0118] The catalysts prepared in the above examples and comparative examples were used to carry out the alkyl transfer reaction of naphthalene / methylnaphthalene with a methyl monocyclic aromatic hydrocarbon in a fixed-bed microreactor. The reaction temperatures are shown in Table 2, the reaction pressure is 2.5 MPa, and the weight hourly space velocity is 1 h⁻¹. -1 The reaction results after 8 hours are shown in Table 2.

[0119] In Table 2, the reaction evaluation results were calculated using the following method:

[0120]

[0121]

[0122] 2,6-Dimethylnaphthalene yield (%) = 2,6-Dimethylnaphthalene selectivity × Naphthalene / methylnaphthalene conversion × 100%.

[0123] Table 2

[0124]

[0125]

[0126] *The composition of the mixed C9 aromatics includes: 60 mol% trimethylbenzene, 20 mol% ethylbenzene, 15 mol% n-propylbenzene, 5 mol% isopropylbenzene, and the molar ratio of 2-methylnaphthalene to trimethylbenzene in the mixed C9 aromatics is 1:5.

[0127] As can be seen from the results in Table 2, the alkyl transfer catalyst prepared in the embodiments of the present invention has higher selectivity and yield for 2,6-dimethylnaphthalene, and good low-temperature activity. While ensuring high feed conversion and product selectivity, it is beneficial to reduce reaction energy consumption and improve the economy of the reaction process.

[0128] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An alkyl transfer catalyst, characterized in that, The catalyst comprises a support and an active metal component supported on the support; wherein the support comprises a twelve-membered ring molecular sieve and a binder; and the active metal component is selected from at least one transition metal. The active metal component is selected from at least one of Cu, Fe, and Zn; The twelve-membered ring molecular sieve is selected from at least one of Y molecular sieve, Beta molecular sieve, MCM-22 molecular sieve, MCM-56 molecular sieve, SAPO-5 molecular sieve, SAPO-37 molecular sieve, and SAPO-40 molecular sieve. The catalyst contains 150-350 μmol / g of Brønsted acid and the ratio of Brønsted acid to Lewis acid is 1.2-3:

1. The catalyst has a specific surface area of ​​250-700 m². 2 / g, the pore volume of the catalyst is 0.28-0.7mL / g.

2. The catalyst according to claim 1, wherein, The amount of Brønsted acid in the catalyst is 180-250 μmol / g.

3. The catalyst according to claim 1, wherein, The catalyst has a specific surface area of ​​300-650 m². 2 / g; And / or, the pore volume of the catalyst is 0.3-0.68 mL / g.

4. The catalyst according to claim 1, wherein, The twelve-membered ring molecular sieve is at least one of Y molecular sieve, Beta molecular sieve and SAPO-5 molecular sieve; And / or, the binder is selected from at least one of alumina, kaolin, attapulgite, bentonite, diatomaceous earth and silica; And / or, based on the total amount of the carrier, the content of the twelve-membered ring molecular sieve is 60-80 wt%; the content of the binder is 20-40 wt%.

5. The catalyst according to claim 4, wherein, The molar ratio of silica to alumina in the twelve-membered ring molecular sieve is 0.1-30; And / or, the adhesive is aluminum oxide; And / or, based on the total amount of the carrier, the content of the twelve-membered ring molecular sieve is 65-75 wt%; the content of the binder is 25-35 wt%.

6. The catalyst according to any one of claims 1-5, wherein, The active metal component is Cu and / or Fe.

7. The catalyst according to any one of claims 1-5, wherein, Based on the total amount of the catalyst, the content of the support is 90-99.9 wt%, and the content of the active metal component, calculated by element, is 0.1-10 wt%.

8. The catalyst according to claim 7, wherein, Based on the total amount of the catalyst, the content of the support is 92-99 wt%, and the content of the active metal component, calculated by element, is 1-8 wt%.

9. A method for preparing the alkyl transfer catalyst according to any one of claims 1-8, comprising: (1) The twelve-membered ring molecular sieve is mixed with the binder precursor, and then molded and dried to obtain the carrier precursor; (2) The carrier precursor is heat-treated by contacting acid solution, and then subjected to first drying and first calcination; (3) In the presence of ultrasound, the product of the first calcination is impregnated with a solution containing an active metal component precursor, and then subjected to a second drying and a second calcination. The active metal component is selected from at least one of the transition metals.

10. The preparation method according to claim 9, wherein, The active metal component is at least one of Cu, Fe and Zn.

11. The preparation method according to claim 9, wherein, The twelve-membered ring molecular sieve is a hydrogen-type twelve-membered ring molecular sieve.

12. The preparation method according to claim 11, wherein, The specific surface area of ​​the twelve-membered ring molecular sieve is 280-740 m². 2 / g.

13. The preparation method according to claim 12, wherein, The specific surface area of ​​the twelve-membered ring molecular sieve is 340-730 m². 2 / g.

14. The preparation method according to claim 11, wherein, The pore volume of the twelve-membered ring molecular sieve is 0.26-0.66 mL / g.

15. The preparation method according to claim 14, wherein, The pore volume of the twelve-membered ring molecular sieve is 0.28-0.64 mL / g.

16. The preparation method according to claim 9, wherein, The dry basis mass ratio of the twelve-membered ring molecular sieve to the binder precursor is 60-80:20-40.

17. The preparation method according to claim 16, wherein, The dry basis mass ratio of the twelve-membered ring molecular sieve to the binder precursor is 65-75:25-35.

18. The preparation method according to claim 9, wherein, The drying conditions described in step (1) include a temperature of 60-180℃ and a time of 4-48 h.

19. The preparation method according to claim 9, wherein, The acid solution is provided by an aqueous solution of acid, the concentration of which is 0.5-3 mol / L.

20. The preparation method according to claim 19, wherein, The acid is selected from at least one of citric acid, ethylenediaminetetraacetic acid, malic acid, tartaric acid, sulfuric acid, phosphoric acid, and nitric acid.

21. The preparation method according to claim 20, wherein, The acid is citric acid and / or phosphoric acid.

22. The preparation method according to claim 9, wherein, The amount of acid solution used is 5-15 mL relative to 1 g of the carrier precursor.

23. The preparation method according to claim 22, wherein, The amount of acid solution used is 8-12 mL relative to 1 g of the carrier precursor.

24. The preparation method according to claim 9, wherein, The heat treatment is performed at a temperature of 40-100℃ for 5-24 hours.

25. The preparation method according to claim 9, wherein, The first drying temperature is 30-200℃, and the time is 0.1-72h.

26. The preparation method according to claim 9, wherein, The first roasting temperature is 380-580℃, and the time is 0.5-20h.

27. The preparation method according to claim 9, wherein, The ultrasonic conditions include: ultrasonic power density of 0.1-10 W / cm². 2 .

28. The preparation method according to any one of claims 9-27, wherein, The immersion temperature is 40-100℃, and the time is 5-24h.

29. The preparation method according to any one of claims 9-27, wherein, The second drying temperature is 30-200℃, and the time is 0.1-72h.

30. The preparation method according to any one of claims 9-27, wherein, The second roasting temperature is 400-600℃, and the time is 0.5-20h.

31. The preparation method according to any one of claims 9-27, wherein, The second drying and the second calcination are carried out under an inert atmosphere.

32. A method for preparing 2,6-dimethylnaphthalene, characterized in that, The method includes: contacting the reactants with a transfer alkylating agent under liquid phase conditions in the presence of a catalyst; The reactants are selected from at least one of naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene; the transfer alkylating agent is a methyl-substituted monocyclic aromatic hydrocarbon. The catalyst is an alkyl transfer catalyst according to any one of claims 1-8.

33. The method according to claim 32, wherein, The transfer alkylating agent is selected from at least one of toluene, xylene, trimethylbenzene, and tetramethylbenzene.

34. The method according to claim 32, wherein, The molar ratio of the reaction raw materials to the transfer alkylating agent is 1:(1-5).

35. The method according to any one of claims 32-34, wherein, The liquid phase conditions include: a reaction temperature of 150-400℃, a reaction pressure of 0.5-5MPa, and a weight hourly space velocity (WHSV) of 0.1-5h for the reactants. -1 .

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