Preparation method of bifunctional catalyst with adjustable surface active sites

Abstract

A preparation method of a bifunctional catalyst with adjustable surface active sites belongs to the technical field of methanol conversion to aromatic hydrocarbon, and comprises the following steps: S1, preparation of a nanoscale H-ZSM-5 catalyst, S2, preparation of a high-dispersion Zn / H-ZSM-5 bifunctional catalyst, S3, introduction of an acidic site regulator, and S4, preparation of the bifunctional catalyst with adjustable surface active sites. S4, introducing a rare earth element modifier, namely adding deionized water by taking nitric acid hexahydrate rare earth metal salt as the rare earth element modifier to obtain an ion exchange solution of rare earth metal, and adding the rare earth doped nano-scale high-dispersion rare earth into the nano-scale high-dispersion acidity-regulated Zn / H-ZSM-5 bifunctional catalyst, carrying out ion exchange reaction, and drying to obtain the nano-scale high-dispersion rare earth doped acidity-regulated Zn / H-ZSM-5 bifunctional catalyst. Through a quadruple synergistic mechanism, metal and acid active center sites on the surface of the Zn / H-ZSM-5 bifunctional catalyst are precisely regulated and controlled, a metal-acid synergistic catalytic reaction path is optimized, BTX selectivity of the catalyst in the MTA reaction process is remarkably improved, and the service life of the catalyst is remarkably prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of methanol conversion to aromatics, and specifically relates to a method for preparing a bifunctional catalyst with controllable surface active sites. Background Art

[0002] Aromatics, as an indispensable basic chemical in the modern industrial system, is widely used in synthetic fibers, engineering plastics, pharmaceutical intermediates and high-performance materials. The balance of supply and demand is directly related to the stability of the national chemical industry chain. my country's aromatics production has long relied on petroleum-based routes. About 80% of aromatics are obtained through naphtha catalytic reforming or cracking processes, but the shortage of petroleum resources and price fluctuations have seriously restricted the development of the industry. Based on the energy structure characteristics of "rich in coal and poor in oil", the development of coal-based methanol to aromatics (MTA) technology has become a key path to breaking through resource bottlenecks. This technology uses methanol as raw material and efficiently produces benzene (B), toluene (T) and xylene (X) through catalytic conversion. It can not only alleviate dependence on petroleum, but also promote the upgrading of coal chemical industry to high-value-added products, and assist in the energy transformation under the "dual carbon" goal.

[0003] The core challenge of methanol to aromatics technology lies in the design and optimization of catalysts. The current mainstream catalyst ZSM-5 molecular sieve exhibits high aromatics selectivity in the MTA reaction due to its unique microporous structure, controllable acidity and thermal stability. However, the micropores of traditional ZSM-5 are easily blocked by carbon precursors, resulting in deactivation of active sites, and the secondary polymerization of light olefins during the reaction easily generates by-products, reducing the yield of the target product. In addition, although single metal-modified ZSM-5 (such as Zn, Ga loading) can improve the aromatization efficiency by adjusting the acid strength and introducing metal centers, the problem of metal sintering significantly shortens the catalyst life during long-term operation. Therefore, the development of multifunctional catalysts with high activity, resistance to carbon deposition and stability has become a key breakthrough point for the industrialization of MTA technology.

[0004] To address these bottlenecks, this study proposes a method for preparing a Zn / H-ZSM-5 bifunctional catalyst with tunable surface active sites for the MTA reaction. Nanocrystal size engineering is employed to manipulate the grain growth direction of ZSM-5, resulting in the synthesis of nanoscale H-ZSM-5 (crystal size <100 nm) with b-axis shape-selective growth. Its shortened pore diffusion path significantly reduces reactant residence time and inhibits carbon deposition. By introducing rare earth elements (such as Ce, La, and Y) and transition metals (Zn and Ga) to construct multi-active centers, the unique 4f electronic structure of rare earth elements enhances metal-support interactions, inhibits the migration and aggregation of active components, and thus improves the catalyst's sintering resistance. Experiments also demonstrate that the rare earth-bimetallic synergistic modification optimizes the acidity distribution of the zeolite, enhancing the directional adsorption of methanol dehydrogenation and aromatization intermediates. The small crystal size effect further promotes mass transfer efficiency, increasing aromatics selectivity to over 55% and extending the catalyst life to 2.3 times that of conventional ZSM-5. This design provides a new approach for the efficient production of coal-based aromatics and also lays a theoretical foundation for the expanded application of multi-metal-molecular sieve catalysts in C1 chemistry.

[0005] Based on the above conclusions, studying a preparation method for a Zn / H-ZSM-5 bifunctional catalyst with tunable surface active sites for MTA reaction will show great prospects and advantages in the MTA reaction process. Summary of the Invention

[0006] In order to overcome some of the problems mentioned in the above background, the present invention provides a method for preparing a bifunctional catalyst with controllable surface active sites, so as to at least partially solve the above problems.

[0007] According to the technical solution of the present invention, a method for preparing a bifunctional catalyst with regulatable surface active sites is provided, comprising the following steps:

[0008] S1. Preparation of nano-scale H-ZSM-5 catalyst: Sodium metaaluminate and sodium hydroxide were used as aluminum source and alkali source, respectively, and were uniformly mixed with deionized water, tetrapropylammonium hydroxide and a composite template according to the ratio of the synthesis liquid. Tetraethyl silicate was then added dropwise as a silicon source. After the addition was completed, the mixture was stirred and aged at 25°C for 24 hours. The aged synthesis liquid was transferred to a crystallization kettle for crystallization, and then centrifuged at a speed of 7000-9000 r / min for 5-10 minutes. The centrifuged sample was placed at 100-1 Drying in a 20°C oven for 6-12 hours to obtain a nano-sized Na-ZSM-5 molecular sieve; placing the nano-sized Na-ZSM-5 molecular sieve in 150-200 ml of a 1 mol / L NH4Cl solution, heating and stirring to perform ion exchange; after the exchange is completed, drying in an 80-120°C oven for 6-24 hours to obtain a nano-sized H-ZSM-5; then placing the obtained nano-sized H-ZSM-5 in an air atmosphere at 550-600°C in a muffle furnace for calcination and activation for 6-8 hours;

[0009] S2. Preparation of a highly dispersed Zn / H-ZSM-5 bifunctional catalyst: using zinc nitrate hexahydrate as a Zn source, a Zn metal impregnation solution is prepared according to an equal volume impregnation method, and then the Zn metal impregnation solution is slowly added dropwise to the nano-scale H-ZSM-5 molecular sieve prepared in (1), and the Zn metal is dispersed by ultrasonic impregnation in an ultrasonic instrument, and then the catalyst solution is placed in a 100-120°C oven for drying for 6-24 hours; after drying, a highly dispersed Zn / H-ZSM-5 bifunctional catalyst is obtained;

[0010] S3. Preparation of a Zn / H-ZSM-5 bifunctional catalyst by introducing an acidic site modifier: deionized water is added in an appropriate ratio to prepare an acidic site modifier ion exchange solution, and then the nano-sized Zn / H-ZSM-5 prepared in (2) is placed in the acidic site modifier ion exchange solution, and ion exchange is carried out under the action of an overhead stirring device and a water bath; after the exchange is completed, the catalyst is placed in an oven at 100-120°C and dried for 6-24 hours to obtain a nano-sized highly dispersed acid-modified Zn / H-ZSM-5 bifunctional catalyst;

[0011] S4. Preparation of Zn / H-ZSM-5 bifunctional catalyst after acid adjustment by introducing rare earth element modifier: Lanthanum nitrate hexahydrate (cerium nitrate hexahydrate / yttrium nitrate hexahydrate) is used as rare earth element modifier, and deionized water is added in an appropriate ratio to prepare an ion exchange solution containing La(Ce / Y) metal. Subsequently, the nano-scale Zn / H-ZSM-5 prepared in (3) after being acted upon by the acid regulator is placed in the La(Ce / Y) metal ion exchange solution, and ion exchange is carried out under the action of an overhead stirring device and a water bath. After the exchange is completed, it is placed in an oven at 100-120°C for drying for 6-24 hours to obtain a nano-scale highly dispersed La(Ce / Y)-doped acid-adjusted Zn / H-ZSM-5 bifunctional catalyst.

[0012] Furthermore, in the preparation of nanoscale H-ZSM-5 catalyst, the composite template used is any one of the following combinations: tetrapropylammonium hydroxide (TPAOH)-n-propylamine (n-PrNH2), tetrapropylammonium hydroxide (TPAOH)-n-butylamine (NPA), and tetrapropylammonium hydroxide (TPAOH)-polyethylene glycol (PEG).

[0013] Furthermore, in the preparation of the nano-scale H-ZSM-5 catalyst, the ratio of the composite template used is 1:1 to 1:3, wherein the tetrapropylammonium hydroxide is 1 and the other template is 1 to 3.

[0014] Furthermore, the molar ratio of the components of the synthetic liquid is: TPAOH:n-PrNH2(NPA / PEG):TEOS:Al2O3:Na2O:H2O=0.4~0.5:0.4~1.5:1:0.005~0.04:0.06~0.1:400~500.

[0015] Furthermore, in the preparation of nano-scale H-ZSM-5 catalyst, the crystallization kettle is a polytetrafluoroethylene-lined crystallization kettle, the crystallization temperature is 175-195°C, and the crystallization time is 24-48 hours. The prepared nano-scale small crystal size H-ZSM-5 catalyst has a crystal size of 60-100 nm.

[0016] Furthermore, in the preparation of highly dispersed Zn / H-ZSM-5 bifunctional catalyst, the conditions for ultrasonic impregnation of Zn metal are as follows: the Zn metal impregnation solution is added dropwise according to the impregnation amount of the catalyst: Zn metal impregnation solution = 1g: 1ml; and the sample after the dropwise addition is placed in an ultrasonic instrument and ultrasonically impregnated at 60°C for 1-2 hours. / Lewis acid ratio is 1-1.5.

[0017] Furthermore, an acidic site regulator is introduced into the preparation of the Zn / H-ZSM-5 bifunctional catalyst, and the acidic site regulator can be one or a combination of gallium nitrate hexahydrate, nickel nitrate hexahydrate or cobalt nitrate hexahydrate.

[0018] Furthermore, an acidic site regulator was introduced into the preparation of a Zn / H-ZSM-5 bifunctional catalyst. The ion exchange introduction conditions of the acidic site regulator were as follows: Ga(Ni / Co) metal impregnation solution was added to a beaker according to the impregnation amount of the catalyst: Ga(Ni / Co) metal impregnation solution = 1 g: 30 ml; and the top stirring device was set to a speed of 300-400 rpm / min, and the mixture was placed in an 80°C water bath for ion exchange for 3-4 hours.

[0019] Furthermore, a rare earth element modifier was introduced into the preparation of the acid-adjusted Zn / H-ZSM-5 bifunctional catalyst, and the conditions for introducing the La(Ce / Y) rare earth element by ion exchange were as follows: the catalyst: La(Ce / Y) rare earth element impregnation solution = 1 g: 30 ml impregnation volume; La(Ce / Y) metal impregnation solution was added to a beaker; and the top stirring device was set to a speed of 300-400 rpm / min, and the catalyst was placed in an 80°C water bath for ion exchange for 3-4 hours.

[0020] The second object of the present invention is to provide an application of a bifunctional catalyst with adjustable surface active sites, wherein 0.6-0.9 g of the nano-scale highly dispersed rare earth doped acid-adjusted Zn / H-ZSM-5 bifunctional catalyst is filled in a fixed bed reactor, the methanol flow rate is controlled to be 0.01-0.04 ml / min, the reaction is carried out at 425-475 ° C, and the mass space velocity is 1-3 h -1 .

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention effectively inhibits the excessive growth of ZSM-5 crystals along the a and c axes by compounding the types of template agents (n-propylamine, n-butylamine, and polyethylene glycol), the addition ratio of the template agents tetrapropylammonium hydroxide (TPAOH) and n-propylamine (n-butylamine / polyethylene glycol), and the crystallization time, and preferentially forms nanoscale grains (crystal size <100nm) that selectively grow along the b-axis (0h0) crystal plane. Compared to the long reaction channels caused by the large crystal size of traditional single template agents, this method significantly increases the specific surface area and mesopore ratio of the molecular sieve while reducing the catalyst crystal size, providing abundant active sites for subsequent metal loading.

[0023] This invention uses multi-level pores to synergistically accelerate mass transfer and inhibit carbon deposit formation. The short b-axis straight pore design of nano-scale H-ZSM-5 forms a continuous three-dimensional diffusion network with the intercrystalline mesopores, shortening the diffusion path of methanol molecules by more than 40%. Combined with the modification of hydroxyl groups on the pore surface by rare earth elements (La / Ce / Y), the adsorption energy barrier of reactants within the pores is reduced, shortening the residence time of intermediates. The carbon deposition rate is reduced by 52% compared to traditional ZSM-5, and the catalyst life is increased to more than 50 hours per pass.

[0024] The present invention enhances aromatization efficiency by synergistically regulating acidity and electronic structure through the introduction of Zn (d10), Ga (d0) and rare earth elements (La 3+ / Ce 4+ / Y 3+ ) Construction of "Zn-Ga-rare earth" ternary active center: Zn 2+ with Ga 3+ High-spin metal clusters are formed through electron transfer, preferentially occupying the B acid sites of the molecular sieve, effectively optimizing and reducing the B / L acid ratio and inhibiting coking caused by strong acids. Rare earth elements regulate the charge distribution of metal clusters through 4f orbital electrons, enhancing the anchoring effect of Zn-Ga on the molecular sieve framework and reducing metal sintering during high-temperature reactions (sintering rate <5%). The ternary synergistic effect increases dehydrogenation activity by 3 times, and the aromatics selectivity reaches 59.3% (compared to 48.7% for unmodified ZSM-5).

[0025] The present invention enhances the kinetics of aromatic hydrocarbon production through targeted optimization of the reaction pathway: under the synergistic effect of the b-axis shape-selective channels and the ternary metal active centers, the methanol conversion pathway is directionally regulated: in the dehydrogenation stage, the Zn-Ga bimetallic accelerates the dehydrogenation of methanol to form a formaldehyde intermediate, and the rare earth element promotes the cleavage of the C-H bond through oxygen vacancies; in the aromatization stage, the weak L-acid center preferentially adsorbs the olefin intermediate, and generates BTX (benzene, toluene, xylene) through the cyclization-dehydrogenation pathway, inhibiting the formation of light alkane byproducts (C1-C4 selectivity <10%); stability is improved: the rare earth-modified molecular sieve framework maintains structural integrity during the cyclic reaction, and after three regenerations, the aromatic hydrocarbon yield still remains at 92% of the initial value. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection.

[0027] This embodiment provides a method for preparing a bifunctional catalyst with regulatable surface active sites, comprising the following steps:

[0028] S1. Preparation of nano-scale H-ZSM-5 catalyst: Sodium metaaluminate and sodium hydroxide were used as aluminum source and alkali source, respectively, and were uniformly mixed with deionized water, tetrapropylammonium hydroxide and a composite template according to the ratio of the synthesis liquid. Tetraethyl silicate was then added dropwise as a silicon source. After the addition was completed, the mixture was stirred and aged at 25°C for 24 hours. The aged synthesis liquid was transferred to a crystallization kettle for crystallization, and then centrifuged at a speed of 7000-9000 r / min for 5-10 minutes. The centrifuged sample was placed at 100-1 Drying in a 20°C oven for 6-12 hours to obtain a nano-sized Na-ZSM-5 molecular sieve; placing the nano-sized Na-ZSM-5 molecular sieve in 150-200 ml of a 1 mol / L NH4Cl solution, heating and stirring to perform ion exchange; after the exchange is completed, drying in an 80-120°C oven for 6-24 hours to obtain a nano-sized H-ZSM-5; then placing the obtained nano-sized H-ZSM-5 in an air atmosphere at 550-600°C in a muffle furnace for calcination and activation for 6-8 hours;

[0029] S2. Preparation of a highly dispersed Zn / H-ZSM-5 bifunctional catalyst: using zinc nitrate hexahydrate as a Zn source, a Zn metal impregnation solution is prepared according to an equal volume impregnation method, and then the Zn metal impregnation solution is slowly added dropwise to the nano-scale H-ZSM-5 molecular sieve prepared in (1), and the Zn metal is dispersed by ultrasonic impregnation in an ultrasonic instrument, and then the catalyst solution is placed in a 100-120°C oven for drying for 6-24 hours; after drying, a highly dispersed Zn / H-ZSM-5 bifunctional catalyst is obtained;

[0030] S3. Preparation of a Zn / H-ZSM-5 bifunctional catalyst by introducing an acidic site modifier: deionized water is added in an appropriate ratio to prepare an acidic site modifier ion exchange solution, and then the nano-sized Zn / H-ZSM-5 prepared in (2) is placed in the acidic site modifier ion exchange solution, and ion exchange is carried out under the action of an overhead stirring device and a water bath; after the exchange is completed, the catalyst is placed in an oven at 100-120°C and dried for 6-24 hours to obtain a nano-sized highly dispersed acid-modified Zn / H-ZSM-5 bifunctional catalyst;

[0031] S4. Preparation of Zn / H-ZSM-5 bifunctional catalyst after acid adjustment by introducing rare earth element modifier: Lanthanum nitrate hexahydrate (cerium nitrate hexahydrate / yttrium nitrate hexahydrate) is used as rare earth element modifier, and deionized water is added in an appropriate ratio to prepare an ion exchange solution containing La(Ce / Y) metal. Subsequently, the nano-scale Zn / H-ZSM-5 prepared in (3) after being acted upon by the acid regulator is placed in the La(Ce / Y) metal ion exchange solution, and ion exchange is carried out under the action of an overhead stirring device and a water bath. After the exchange is completed, it is placed in an oven at 100-120°C for drying for 6-24 hours to obtain a nano-scale highly dispersed La(Ce / Y)-doped acid-adjusted Zn / H-ZSM-5 bifunctional catalyst.

[0032] In a further embodiment of this embodiment, in the preparation of the nanoscale H-ZSM-5 catalyst, the composite template used is any one of the following combinations: tetrapropylammonium hydroxide (TPAOH)-n-propylamine (n-Pr NH2), tetrapropylammonium hydroxide (TPAOH)-n-butylamine (NPA), tetrapropylammonium hydroxide (TPAO H)-polyethylene glycol (PEG).

[0033] In a further embodiment of this example, in the preparation of the nano-scale H-ZSM-5 catalyst, the ratio of the composite template used is 1:1 to 1:3, wherein the tetrapropylammonium hydroxide is 1 and the other template is 1 to 3.

[0034] In a further embodiment of this embodiment, the molar ratio of the components of the synthetic liquid is: TPAOH:

[0035] n-PrNH2(NPA / PEG): TEOS:Al2O3:Na2O:H2O=0.4~0.5:0.4~1.5:1:0.005~0.04:0.06~0.1:400~500.

[0036] In a further embodiment of this example, in the preparation of a nano-sized H-ZSM-5 catalyst, the crystallization kettle is a polytetrafluoroethylene-lined crystallization kettle, the crystallization temperature is 175-195°C, and the crystallization time is 24-48 hours. The prepared nano-sized H-ZSM-5 catalyst has a crystal size of 60-100 nm.

[0037] In a further embodiment of this example, in the preparation of a highly dispersed Zn / H-ZSM-5 bifunctional catalyst, the conditions for ultrasonic impregnation of Zn metal are as follows: the Zn metal impregnation solution is added dropwise according to the impregnation amount of the catalyst: Zn metal impregnation solution = 1g: 1ml; and the sample after the dropwise addition is placed in an ultrasonic instrument and ultrasonically impregnated at 60°C for 1-2 hours. / Lewis acid ratio is 1-1.5.

[0038] In a further embodiment of this example, an acidic site regulator is introduced into the preparation of the Zn / H-ZSM-5 bifunctional catalyst. The acidic regulator can be one or a combination of gallium nitrate hexahydrate, nickel nitrate hexahydrate or cobalt nitrate hexahydrate.

[0039] In a further embodiment of this embodiment, the acidic site regulator is introduced into the preparation of the Zn / H-ZSM-5 bifunctional catalyst, and the ion exchange introduction conditions of the acidic site regulator are as follows: Ga(Ni / Co) metal impregnation solution is added to the beaker according to the impregnation amount of the catalyst: Ga(Ni / Co) metal impregnation solution = 1g:30ml; and the top stirring device is set to a speed of 300-400rpm / min, and the ion exchange is carried out in a water bath at 80°C for 3-4h.

[0040] In a further embodiment of this embodiment, a rare earth element modifier is introduced into the preparation of the acid-adjusted Zn / H-ZSM-5 bifunctional catalyst, and the conditions for introducing the La(Ce / Y) rare earth element by ion exchange are as follows: the catalyst: La(Ce / Y) rare earth element impregnation solution = 1g: 30ml impregnation amount; La(Ce / Y) metal impregnation solution is added to a beaker; and the top stirring device is set to a speed of 300-400rpm / min, and the ion exchange is carried out in a water bath at 80°C for 3-4h.

[0041] The second object of the present invention is to provide an application of a bifunctional catalyst with adjustable surface active sites, wherein 0.6-0.9 g of the nano-scale highly dispersed rare earth doped acid-adjusted Zn / H-ZSM-5 bifunctional catalyst is filled in a fixed bed reactor, the methanol flow rate is controlled to be 0.01-0.04 ml / min, the reaction is carried out at 425-475 ° C, and the mass space velocity is 1-3 h -1 .

[0042] Example 1

[0043] A method for preparing a Zn / H-ZSM-5 bifunctional catalyst with controllable surface active sites for MTA reaction, wherein the synthesis liquid ratio is: TPAOH:n-PrNH2:TEOS:Al2O3:Na2O:H2O=0.48:0.96:1:0.04:0.075:400; that is, the addition amounts of the synthesis liquid components are: for every 1 part of tetraethyl silicate (TEOS), it is necessary to add 0.48 parts of tetrapropylammonium hydroxide (TPAOH), 0.96 parts of n-propylamine (n-PrNH2), 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, and 400 parts of water; in addition, it is necessary to impregnate 0.5wt% of Zn metal by ultrasonic impregnation, introduce 1.5wt% of Ga metal by ion exchange, and introduce 1.0wt% of La (Ce / Y) rare earth elements by ion exchange.

[0044] The preparation method comprises the following steps:

[0045] S1: Synthesis Solution Aging Preparation: According to the synthesis solution ratio, the aging reaction was carried out at room temperature of 25°C using a magnetic stirrer. 400 parts of water, 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, 0.48 parts of tetrapropylammonium hydroxide, and 0.96 parts of n-propylamine were added to an Erlenmeyer flask in sequence. Then, 1 part of tetraethyl silicate was added dropwise at a rate of 6-8 seconds per drop. After all the chemicals were added, the mixture was stirred and aged for 24 hours.

[0046] S2: Preparation of Nanosized H-ZSM-5 Molecular Sieve: The aged synthesis solution was added to a hydrothermal synthesis reactor and placed in a polytetrafluoroethylene-lined crystallization reactor for crystallization at 180°C for 24 hours. The sample was then centrifuged at 9000 rpm for 10 minutes and dried in a 120°C oven for 12 hours to obtain nanosized Na-ZSM-5 molecular sieve.

[0047] S3: Preparation of Na-type reduced H-ZSM-5 molecular sieve: The prepared nano-sized Na-ZSM-5 molecular sieve was placed in a beaker filled with an excess of 1 mol / L NH4Cl solution and heated and stirred in a water bath at 80°C and 300 rpm for 3 h for ion exchange. After the exchange, the nano-sized H-ZSM-5 molecular sieve was dried at 120°C for 12 h to obtain the obtained product.

[0048] S4: Molecular sieve activation preparation: The prepared nano-scale H-ZSM-5 molecular sieve is placed in a muffle furnace with an air atmosphere and a flow rate of 400 ml / min for calcination activation. The muffle furnace temperature is set to 600°C and the activation time is 6 hours. After the activation is completed, the nano-scale H-ZSM-5 molecular sieve that can be impregnated with metal is obtained.

[0049] S5: Zn metal impregnation nano H-ZSM-5 molecular sieve: Place the nano-scale H-ZSM-5 molecular sieve in a 15ml centrifuge tube and add the Zn metal impregnation solution dropwise according to the impregnation amount of catalyst: Zn metal impregnation solution = 1g:1ml; and place the sample after the dropwise addition in an ultrasonic instrument for ultrasonic impregnation at 60℃ for 1.5h, and then dry it in a 120℃ oven for 12h.

[0050] S6: Ga metal impregnation of Zn-type nano H-ZSM-5 molecular sieve: Place the nano Zn / H-ZSM-5 molecular sieve in a 200 ml beaker, add Ga metal impregnation solution to the beaker according to the impregnation amount of catalyst: Ga metal impregnation solution = 1 g: 30 ml; and place it in an 80°C water bath for ion exchange for 3 hours with the top stirring device set to 300 rpm / min, then centrifuge and dry in a 120°C oven for 12 hours.

[0051] S7: Rare earth metal La(Ce / Y) doped [Zn, Ga] / nano H-ZSM-5 molecular sieve: Place the nano [Zn, Ga] / H-ZSM-5 molecular sieve in a 200ml beaker, add La(Ce / Y) metal impregnation solution to the beaker according to the impregnation amount of catalyst: La(Ce / Y) metal impregnation solution = 1g:30ml; and place the mixture in an 80℃ water bath for ion exchange for 3h with the top stirring device set to 300rpm / min, then centrifuge and dry in a 120℃ oven for 12h.

[0052] Example 2

[0053] A method for preparing a Zn / H-ZSM-5 bifunctional catalyst with controllable surface active sites for an MTA reaction, wherein the synthesis liquid ratio is: TPAOH:NPA:TEOS:Al2O3:Na2O:H2O=0.48:0.96:1:0.04:0.075:400; that is, the addition amounts of the synthesis liquid components are: for every 1 part of tetraethyl silicate (TEOS), 0.48 parts of tetrapropylammonium hydroxide (TPAOH), 0.96 parts of n-butylamine (NPA), 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, and 400 parts of water are required; in addition, 0.5 wt% of Zn metal is impregnated by ultrasonic impregnation, 1.5 wt% of Ga metal is introduced by ion exchange, and 1.0 wt% of La (Ce / Y) rare earth elements are introduced by ion exchange.

[0054] The preparation method comprises the following steps:

[0055] S1: Synthesis solution aging preparation: According to the synthesis solution ratio, aging reaction was carried out at room temperature of 25°C using a magnetic stirrer. 400 parts of water, 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, 0.48 parts of tetrapropylammonium hydroxide, and 0.96 parts of n-butylamine were added to an Erlenmeyer flask in sequence. Then, 1 part of tetraethyl silicate was added dropwise at a rate of 6-8 seconds per drop. After all the chemicals were added, stirring and aging were carried out for 24 hours.

[0056] S2: Preparation of Nanosized H-ZSM-5 Molecular Sieve: The aged synthesis solution was added to a hydrothermal synthesis reactor and placed in a polytetrafluoroethylene-lined crystallization reactor for crystallization at 180°C for 24 hours. The sample was then centrifuged at 9000 rpm for 10 minutes and dried in a 120°C oven for 12 hours to obtain nanosized Na-ZSM-5 molecular sieve.

[0057] S3: Preparation of Na-type reduced H-ZSM-5 molecular sieve: The prepared nano-sized Na-ZSM-5 molecular sieve was placed in a beaker filled with an excess of 1 mol / L NH4Cl solution and heated and stirred in a water bath at 80°C and 300 rpm for 3 h for ion exchange. After the exchange, the nano-sized H-ZSM-5 molecular sieve was dried at 120°C for 12 h to obtain the obtained product.

[0058] S4: Molecular sieve activation preparation: The prepared nano-scale H-ZSM-5 molecular sieve is placed in a muffle furnace with an air atmosphere and a flow rate of 400 ml / min for calcination activation. The muffle furnace temperature is set to 600°C and the activation time is 6 hours. After the activation is completed, the nano-scale H-ZSM-5 molecular sieve that can be impregnated with metal is obtained.

[0059] S5: Zn metal impregnation nano H-ZSM-5 molecular sieve: Place the nano-scale H-ZSM-5 molecular sieve in a 15ml centrifuge tube and add the Zn metal impregnation solution dropwise according to the impregnation amount of catalyst: Zn metal impregnation solution = 1g:1ml; and place the sample after the dropwise addition in an ultrasonic instrument for ultrasonic impregnation at 60℃ for 1.5h, and then dry it in a 120℃ oven for 12h.

[0060] S6: Ga metal impregnation of Zn-type nano H-ZSM-5 molecular sieve: Place the nano Zn / H-ZSM-5 molecular sieve in a 200 ml beaker, add Ga metal impregnation solution to the beaker according to the impregnation amount of catalyst: Ga metal impregnation solution = 1 g: 30 ml; and place it in an 80°C water bath for ion exchange for 3 hours with the top stirring device set to 300 rpm / min, then centrifuge and dry in a 120°C oven for 12 hours.

[0061] S7: Rare earth metal La(Ce / Y) doped [Zn, Ga] / nano H-ZSM-5 molecular sieve: Place the nano [Zn, Ga] / H-ZSM-5 molecular sieve in a 200ml beaker, add La(Ce / Y) metal impregnation solution to the beaker according to the impregnation amount of catalyst: La(Ce / Y) metal impregnation solution = 1g:30ml; and place the mixture in an 80℃ water bath for ion exchange for 3h with the top stirring device set to 300rpm / min, then centrifuge and dry in a 120℃ oven for 12h.

[0062] Example 3

[0063] A method for preparing a Zn / H-ZSM-5 bifunctional catalyst with controllable surface active sites for MTA reaction, wherein the synthesis liquid ratio is: TPAOH:PEG:TEOS:Al2O3:Na2O:H2O=0.48:0.96:1:0.04:0.075:400; that is, the addition amounts of the synthesis liquid components are: for every 1 part of tetraethyl silicate (TEOS), 0.48 parts of tetrapropylammonium hydroxide (TPAOH), 0.96 parts of polyethylene glycol (PEG), 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, and 400 parts of water are required; in addition, 0.5 wt% of Zn metal is impregnated by ultrasonic impregnation, 1.5 wt% of Ga metal is introduced by ion exchange, and 1.0 wt% of La (Ce / Y) rare earth elements are introduced by ion exchange.

[0064] The preparation method comprises the following steps:

[0065] S1: Synthesis solution aging preparation: According to the synthesis solution ratio, aging reaction was carried out at room temperature of 25°C using a magnetic stirrer. 400 parts of water, 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, 0.48 parts of tetrapropylammonium hydroxide, and 0.96 parts of polyethylene glycol (PEG) were added to an Erlenmeyer flask in sequence. Then, 1 part of tetraethyl silicate was added dropwise at a rate of 6-8 seconds per drop. After all the drugs were added, stirring and aging were carried out for 24 hours.

[0066] S2: Preparation of Nanosized H-ZSM-5 Molecular Sieve: The aged synthesis solution was added to a hydrothermal synthesis reactor and placed in a polytetrafluoroethylene-lined crystallization reactor for crystallization at 180°C for 24 hours. The sample was then centrifuged at 9000 rpm for 10 minutes and dried in a 120°C oven for 12 hours to obtain nanosized Na-ZSM-5 molecular sieve.

[0067] S3: Preparation of Na-type reduced H-ZSM-5 molecular sieve: The prepared nano-sized Na-ZSM-5 molecular sieve was placed in a beaker filled with an excess of 1 mol / L NH4Cl solution and heated and stirred in a water bath at 80°C and 300 rpm for 3 h for ion exchange. After the exchange, the nano-sized H-ZSM-5 molecular sieve was dried at 120°C for 12 h to obtain the obtained product.

[0068] S4: Molecular sieve activation preparation: The prepared nano-scale H-ZSM-5 molecular sieve is placed in a muffle furnace with an air atmosphere and a flow rate of 400 ml / min for calcination activation. The muffle furnace temperature is set to 600°C and the activation time is 6 hours. After the activation is completed, the nano-scale H-ZSM-5 molecular sieve that can be impregnated with metal is obtained.

[0069] S5: Zn metal impregnation nano H-ZSM-5 molecular sieve: Place the nano-scale H-ZSM-5 molecular sieve in a 15ml centrifuge tube and add the Zn metal impregnation solution dropwise according to the impregnation amount of catalyst: Zn metal impregnation solution = 1g:1ml; and place the sample after the dropwise addition in an ultrasonic instrument for ultrasonic impregnation at 60℃ for 1.5h, and then dry it in a 120℃ oven for 12h.

[0070] S6: Ga metal impregnation of Zn-type nano H-ZSM-5 molecular sieve: Place the nano Zn / H-ZSM-5 molecular sieve in a 200 ml beaker, add Ga metal impregnation solution to the beaker according to the impregnation amount of catalyst: Ga metal impregnation solution = 1 g: 30 ml; and place it in an 80°C water bath for ion exchange for 3 hours with the top stirring device set to 300 rpm / min, then centrifuge and dry in a 120°C oven for 12 hours.

[0071] S7: Rare earth metal La(Ce / Y) doped [Zn, Ga] / nano H-ZSM-5 molecular sieve: Place the nano [Zn, Ga] / H-ZSM-5 molecular sieve in a 200ml beaker, add La(Ce / Y) metal impregnation solution to the beaker according to the impregnation amount of catalyst: La(Ce / Y) metal impregnation solution = 1g:30ml; and place the mixture in an 80℃ water bath for ion exchange for 3h with the top stirring device set to 300rpm / min, then centrifuge and dry in a 120℃ oven for 12h.

[0072] Example 4

[0073] A method for preparing a Zn / H-ZSM-5 bifunctional catalyst with controllable surface active sites for MTA reaction, wherein the synthesis liquid ratio is: TPAOH:n-PrNH2:TEOS:Al2O3:Na2O:H2O=0.48:1.44:1:0.04:0.075:400; that is, the addition amounts of the synthesis liquid components are: for every 1 part of tetraethyl silicate (TEOS), it is necessary to add 0.48 parts of tetrapropylammonium hydroxide (TPAOH), 1.44 parts of n-propylamine (n-PrNH2), 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, and 400 parts of water; in addition, it is necessary to impregnate 0.5wt% of Zn metal by ultrasonic impregnation, introduce 1.5wt% of Ga metal by ion exchange, and introduce 1.0wt% of La (Ce / Y) rare earth elements by ion exchange.

[0074] The preparation method comprises the following steps:

[0075] S1: Synthesis solution aging preparation: According to the synthesis solution ratio, aging reaction was carried out at room temperature of 25°C using a magnetic stirrer. 400 parts of water, 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, 0.48 parts of tetrapropylammonium hydroxide, and 1.44 parts of n-propylamine were added to an Erlenmeyer flask in sequence. Then, 1 part of tetraethyl silicate was added dropwise at a rate of 6-8 seconds per drop. After all the chemicals were added, stirring and aging were carried out for 24 hours.

[0076] S2: Preparation of Nanosized H-ZSM-5 Molecular Sieve: The aged synthesis solution was added to a hydrothermal synthesis reactor and placed in a polytetrafluoroethylene-lined crystallization reactor for crystallization at 180°C for 24 hours. The sample was then centrifuged at 9000 rpm for 10 minutes and dried in a 120°C oven for 12 hours to obtain nanosized Na-ZSM-5 molecular sieve.

[0077] S3: Preparation of Na-type reduced H-ZSM-5 molecular sieve: The prepared nano-sized Na-ZSM-5 molecular sieve was placed in a beaker filled with an excess of 1 mol / L NH4Cl solution and heated and stirred in a water bath at 80°C and 300 rpm for 3 h for ion exchange. After the exchange, the nano-sized H-ZSM-5 molecular sieve was dried at 120°C for 12 h to obtain the obtained product.

[0078] S4: Molecular sieve activation preparation: The prepared nano-scale H-ZSM-5 molecular sieve is placed in a muffle furnace with an air atmosphere and a flow rate of 400 ml / min for calcination activation. The muffle furnace temperature is set to 600°C and the activation time is 6 hours. After the activation is completed, the nano-scale H-ZSM-5 molecular sieve that can be impregnated with metal is obtained.

[0079] S5: Zn metal impregnation nano H-ZSM-5 molecular sieve: Place the nano-scale H-ZSM-5 molecular sieve in a 15ml centrifuge tube and add the Zn metal impregnation solution dropwise according to the impregnation amount of catalyst: Zn metal impregnation solution = 1g:1ml; and place the sample after the dropwise addition in an ultrasonic instrument for ultrasonic impregnation at 60℃ for 1.5h, and then dry it in a 120℃ oven for 12h.

[0080] S6: Ga metal impregnation of Zn-type nano H-ZSM-5 molecular sieve: Place the nano Zn / H-ZSM-5 molecular sieve in a 200 ml beaker, add Ga metal impregnation solution to the beaker according to the impregnation amount of catalyst: Ga metal impregnation solution = 1 g: 30 ml; and place it in an 80°C water bath for ion exchange for 3 hours with the top stirring device set to 300 rpm / min, then centrifuge and dry in a 120°C oven for 12 hours.

[0081] S7: Rare earth metal La(Ce / Y) doped [Zn, Ga] / nano H-ZSM-5 molecular sieve: Place the nano [Zn, Ga] / H-ZSM-5 molecular sieve in a 200ml beaker, add La(Ce / Y) metal impregnation solution to the beaker according to the impregnation amount of catalyst: La(Ce / Y) metal impregnation solution = 1g:30ml; and place the mixture in an 80℃ water bath for ion exchange for 3h with the top stirring device set to 300rpm / min, then centrifuge and dry in a 120℃ oven for 12h.

[0082] Example 5

[0083] A method for preparing a Zn / H-ZSM-5 bifunctional catalyst with controllable surface active sites for MTA reaction, wherein the synthesis liquid ratio is: TPAOH:n-PrNH2:TEOS:Al2O3:Na2O:H2O=0.48:0.96:1:0.04:0.075:400; that is, the addition amounts of the synthesis liquid components are: for every 1 part of tetraethyl silicate (TEOS), 0.48 parts of tetrapropylammonium hydroxide (TPAOH), 0.96 parts of n-propylamine (n-PrNH2), 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, and 400 parts of water are required; in addition, 1.0wt% of Zn metal is impregnated by ultrasonic impregnation, 1.5wt% of Ga metal is introduced by ion exchange, and 1.0wt% of La (Ce / Y) rare earth elements are introduced by ion exchange.

[0084] The preparation method comprises the following steps:

[0085] S1: Synthesis Solution Aging Preparation: According to the synthesis solution ratio, the aging reaction was carried out at room temperature of 25°C using a magnetic stirrer. 400 parts of water, 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, 0.48 parts of tetrapropylammonium hydroxide, and 0.96 parts of n-propylamine were added to an Erlenmeyer flask in sequence. Then, 1 part of tetraethyl silicate was added dropwise at a rate of 6-8 seconds per drop. After all the chemicals were added, the mixture was stirred and aged for 24 hours.

[0086] S2: Preparation of Nanosized H-ZSM-5 Molecular Sieve: The aged synthesis solution was added to a hydrothermal synthesis reactor and placed in a polytetrafluoroethylene-lined crystallization reactor for crystallization at 180°C for 24 hours. The sample was then centrifuged at 9000 rpm for 10 minutes and dried in a 120°C oven for 12 hours to obtain nanosized Na-ZSM-5 molecular sieve.

[0087] S3: Preparation of Na-type reduced H-ZSM-5 molecular sieve: The prepared nano-sized Na-ZSM-5 molecular sieve was placed in a beaker filled with an excess of 1 mol / L NH4Cl solution and heated and stirred in a water bath at 80°C and 300 rpm for 3 h for ion exchange. After the exchange, the nano-sized H-ZSM-5 molecular sieve was dried at 120°C for 12 h to obtain the obtained product.

[0088] S4: Molecular sieve activation preparation: The prepared nano-scale H-ZSM-5 molecular sieve is placed in a muffle furnace with an air atmosphere and a flow rate of 400 ml / min for calcination activation. The muffle furnace temperature is set to 600°C and the activation time is 6 hours. After the activation is completed, the nano-scale H-ZSM-5 molecular sieve that can be impregnated with metal is obtained.

[0089] S5: Zn metal impregnation nano H-ZSM-5 molecular sieve: Place the nano-scale H-ZSM-5 molecular sieve in a 15ml centrifuge tube and add the Zn metal impregnation solution dropwise according to the impregnation amount of catalyst: Zn metal impregnation solution = 1g:1ml; and place the sample after the dropwise addition in an ultrasonic instrument for ultrasonic impregnation at 60℃ for 1.5h, and then dry it in a 120℃ oven for 12h.

[0090] S6: Ga metal impregnation of Zn-type nano H-ZSM-5 molecular sieve: Place the nano Zn / H-ZSM-5 molecular sieve in a 200 ml beaker, add Ga metal impregnation solution to the beaker according to the impregnation amount of catalyst: Ga metal impregnation solution = 1 g: 30 ml; and place it in an 80°C water bath for ion exchange for 3 hours with the top stirring device set to 300 rpm / min, then centrifuge and dry in a 120°C oven for 12 hours.

[0091] S7: Rare earth metal La(Ce / Y) doped [Zn, Ga] / nano H-ZSM-5 molecular sieve: Place the nano [Zn, Ga] / H-ZSM-5 molecular sieve in a 200ml beaker, add La(Ce / Y) metal impregnation solution to the beaker according to the impregnation amount of catalyst: La(Ce / Y) metal impregnation solution = 1g:30ml; and place the mixture in an 80℃ water bath for ion exchange for 3h with the top stirring device set to 300rpm / min, then centrifuge and dry in a 120℃ oven for 12h.

[0092] Example 6

[0093] A method for preparing a Zn / H-ZSM-5 bifunctional catalyst with regulated surface active sites for MTA reaction, wherein the synthesis liquid ratio is: TPAOH:n-PrNH2:TEOS:Al2O3:Na2O:H2O=0.48:0.96:1:0.04:0.075:400; that is, the addition amounts of the synthesis liquid components are: for every 1 part of tetraethyl silicate (TEOS), 0.48 parts of tetrapropylammonium hydroxide (TPAOH), 0.96 parts of n-propylamine, 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, and 400 parts of water are required; in addition, 0.5wt% of Zn metal is impregnated by ultrasonic impregnation, 1.0wt% of Ga metal is introduced by ion exchange, and 1.0wt% of La (Ce / Y) rare earth elements are introduced by ion exchange.

[0094] The preparation method comprises the following steps:

[0095] S1: Synthesis Solution Aging Preparation: According to the synthesis solution ratio, the aging reaction was carried out at room temperature of 25°C using a magnetic stirrer. 400 parts of water, 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, 0.48 parts of tetrapropylammonium hydroxide, and 0.96 parts of n-propylamine were added to an Erlenmeyer flask in sequence. Then, 1 part of tetraethyl silicate was added dropwise at a rate of 6-8 seconds per drop. After all the chemicals were added, the mixture was stirred and aged for 24 hours.

[0096] S2: Preparation of Nanosized H-ZSM-5 Molecular Sieve: The aged synthesis solution was added to a hydrothermal synthesis reactor and placed in a polytetrafluoroethylene-lined crystallization reactor for crystallization at 180°C for 24 hours. The sample was then centrifuged at 9000 rpm for 10 minutes and dried in a 120°C oven for 12 hours to obtain nanosized Na-ZSM-5 molecular sieve.

[0097] S3: Preparation of Na-type reduced H-ZSM-5 molecular sieve: The prepared nano-sized Na-ZSM-5 molecular sieve was placed in a beaker filled with an excess of 1 mol / L NH4Cl solution and heated and stirred in a water bath at 80°C and 300 rpm for 3 h for ion exchange. After the exchange, the nano-sized H-ZSM-5 molecular sieve was dried at 120°C for 12 h to obtain the obtained product.

[0098] S4: Molecular sieve activation preparation: The prepared nano-scale H-ZSM-5 molecular sieve is placed in a muffle furnace with an air atmosphere and a flow rate of 400 ml / min for calcination activation. The muffle furnace temperature is set to 600°C and the activation time is 6 hours. After the activation is completed, the nano-scale H-ZSM-5 molecular sieve that can be impregnated with metal is obtained.

[0099] S5: Zn metal impregnation nano H-ZSM-5 molecular sieve: Place the nano-scale H-ZSM-5 molecular sieve in a 15ml centrifuge tube and add the Zn metal impregnation solution dropwise according to the impregnation amount of catalyst: Zn metal impregnation solution = 1g:1ml; and place the sample after the dropwise addition in an ultrasonic instrument for ultrasonic impregnation at 60℃ for 1.5h, and then dry it in a 120℃ oven for 12h.

[0100] S6: Ga metal impregnation of Zn-type nano H-ZSM-5 molecular sieve: Place the nano Zn / H-ZSM-5 molecular sieve in a 200 ml beaker, add Ga metal impregnation solution to the beaker according to the impregnation amount of catalyst: Ga metal impregnation solution = 1 g: 30 ml; and place it in an 80°C water bath for ion exchange for 3 hours with the top stirring device set to 300 rpm / min, then centrifuge and dry in a 120°C oven for 12 hours.

[0101] S7: Rare earth metal La(Ce / Y) doped [Zn, Ga] / nano H-ZSM-5 molecular sieve: Place the nano [Zn, Ga] / H-ZSM-5 molecular sieve in a 200ml beaker, add La(Ce / Y) metal impregnation solution to the beaker according to the impregnation amount of catalyst: La(Ce / Y) metal impregnation solution = 1g:30ml; and place the mixture in an 80℃ water bath for ion exchange for 3h with the top stirring device set to 300rpm / min, then centrifuge and dry in a 120℃ oven for 12h.

[0102] Example 7

[0103] A method for preparing a Zn / H-ZSM-5 bifunctional catalyst with controllable surface active sites for MTA reaction, wherein the synthesis liquid ratio is: TPAOH:n-PrNH2:TEOS:Al2O3:Na2O:H2O=0.48:0.96:1:0.04:0.075:400; that is, the addition amounts of the synthesis liquid components are: for every 1 part of tetraethyl silicate (TEOS), 0.48 parts of tetrapropylammonium hydroxide (TPAOH), 0.96 parts of n-propylamine (n-PrNH2), 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, and 400 parts of water are required; in addition, 0.5wt% of Zn metal is impregnated by ultrasonic impregnation, 1.5wt% of Ga metal is introduced by ion exchange, and 1.5wt% of La (Ce / Y) rare earth elements are introduced by ion exchange.

[0104] The preparation method comprises the following steps:

[0105] S1: Synthesis Solution Aging Preparation: According to the synthesis solution ratio, the aging reaction was carried out at room temperature of 25°C using a magnetic stirrer. 400 parts of water, 0.04 parts of sodium metaaluminate, 0.075 parts of sodium hydroxide, 0.48 parts of tetrapropylammonium hydroxide, and 0.96 parts of n-propylamine were added to an Erlenmeyer flask in sequence. Then, 1 part of tetraethyl silicate was added dropwise at a rate of 6-8 seconds per drop. After all the chemicals were added, the mixture was stirred and aged for 24 hours.

[0106] S2: Preparation of Nanosized H-ZSM-5 Molecular Sieve: The aged synthesis solution was added to a hydrothermal synthesis reactor and placed in a polytetrafluoroethylene-lined crystallization reactor for crystallization at 180°C for 24 hours. The sample was then centrifuged at 9000 rpm for 10 minutes and dried in a 120°C oven for 12 hours to obtain nanosized Na-ZSM-5 molecular sieve.

[0107] S3: Preparation of Na-type reduced H-ZSM-5 molecular sieve: The prepared nano-sized Na-ZSM-5 molecular sieve was placed in a beaker filled with an excess of 1 mol / L NH4Cl solution and heated and stirred in a water bath at 80°C and 300 rpm for 3 h for ion exchange. After the exchange, the nano-sized H-ZSM-5 molecular sieve was dried at 120°C for 12 h to obtain the obtained product.

[0108] S4: Molecular sieve activation preparation: The prepared nano-scale H-ZSM-5 molecular sieve is placed in a muffle furnace with an air atmosphere and a flow rate of 400 ml / min for calcination activation. The muffle furnace temperature is set to 600°C and the activation time is 6 hours. After the activation is completed, the nano-scale H-ZSM-5 molecular sieve that can be impregnated with metal is obtained.

[0109] S5: Zn metal impregnation nano H-ZSM-5 molecular sieve: Place the nano-scale H-ZSM-5 molecular sieve in a 15ml centrifuge tube and add the Zn metal impregnation solution dropwise according to the impregnation amount of catalyst: Zn metal impregnation solution = 1g:1ml; and place the sample after the dropwise addition in an ultrasonic instrument for ultrasonic impregnation at 60℃ for 1.5h, and then dry it in a 120℃ oven for 12h.

[0110] S6: Ga metal impregnation of Zn-type nano H-ZSM-5 molecular sieve: Place the nano Zn / H-ZSM-5 molecular sieve in a 200 ml beaker, add Ga metal impregnation solution to the beaker according to the impregnation amount of catalyst: Ga metal impregnation solution = 1 g: 30 ml; and place it in an 80°C water bath for ion exchange for 3 hours with the top stirring device set to 300 rpm / min, then centrifuge and dry in a 120°C oven for 12 hours.

[0111] S7: Rare earth metal La(Ce / Y) doped [Zn, Ga] / nano H-ZSM-5 molecular sieve: Place the nano [Zn, Ga] / H-ZSM-5 molecular sieve in a 200ml beaker, add La(Ce / Y) metal impregnation solution to the beaker according to the impregnation amount of catalyst: La(Ce / Y) metal impregnation solution = 1g:30ml; and place the mixture in an 80℃ water bath for ion exchange for 3h with the top stirring device set to 300rpm / min, then centrifuge and dry in a 120℃ oven for 12h.

[0112] Comparative Example 1

[0113] A pure Nano-ZSM-5 molecular sieve grown along the b-axis crystal plane without adding metal was used for comparison. The synthetic liquid ratio was: TPAOH:n-PrNH2:TEOS:Al2O3:Na2O:H2O=0.48:0.96:1:0.04:0.075:400. That is, the amount of synthetic liquid components added was: 400 parts of water, 0.48 parts of tetrapropylammonium hydroxide (TPAOH), 0.96 parts of n-propylamine (n-PrNH2), 0.04 parts of sodium metaaluminate, and 0.075 parts of sodium hydroxide for every 1 part of tetraethyl silicate (TEOS). The other steps were the same as in Example 1, except that steps S5-S7 were not performed for impregnation of metal.

[0114] Comparative Example 2

[0115] A Zn / Nano-ZSM-5 molecular sieve prepared without adding Ga metal and rare earth element La(Ce / Y) was used for comparison. Ga metal and rare earth element La(Ce / Y) were not added during the preparation process, and the synthetic liquid ratio was: TPAOH:n-PrNH2:TEOS:Al2O3:Na2O:H2O=0.48:0.96:1:0.04:0.075:400. That is, the amount of synthetic liquid components added was: for every 1 part of tetraethyl silicate (TEOS), 400 parts of water, 0.48 parts of tetrapropylammonium hydroxide (TPAOH), 0.96 parts of n-propylamine (n-PrNH2), 0.04 parts of sodium metaaluminate, and 0.075 parts of sodium hydroxide were added. The other steps were the same as in Example 1, except that steps S6-S7 were not performed to impregnate Ga metal and rare earth element La(Ce / Y).

[0116] Comparative Example 3

[0117] [Zn, Ga] / Nano-ZSM-5 molecular sieve was prepared without adding rare earth element La(Ce / Y) for comparison. No rare earth element La(Ce / Y) was added during the preparation process, and the synthetic liquid ratio was: TPAOH:n-PrNH2:TEOS:Al2O3:Na2O:H2O=0.48:0.96:1:0.04:0.075:400. That is, the amount of synthetic liquid components added was: for every 1 part of tetraethyl silicate (TEOS), 400 parts of water, 0.48 parts of tetrapropylammonium hydroxide (TPAOH), 0.96 parts of n-propylamine (n-PrNH2), 0.04 parts of sodium metaaluminate, and 0.075 parts of sodium hydroxide were required. The other steps were the same as in Example 1, except that step S7 for impregnation of rare earth element La(Ce / Y) was not performed.

[0118] The La-[Zn, Ga] / Nano-H-ZSM-5 molecular sieves obtained in Examples 1-7 and the pure Nano-H-ZSM-5, Zn / Nano-H-ZSM-5, and [Zn, Ga] / Nano-H-ZSM-5 molecular sieves obtained in Comparative Examples 1-3 were used as catalysts in a coal-based methanol-to-aromatics reaction. The reaction conditions were a catalyst loading of 0.6 g in a fixed-bed reactor, a methanol flow rate of 0.02 ml / min, a reaction temperature of 450°C, and a mass space velocity of 2 h⁻¹. The methanol conversion and aromatics selectivity obtained were compared, and the results are shown in Table 1.

[0119] Table 1 Comparison of methanol conversion and aromatics selectivity in catalytic MTA reaction

[0120]

[0121] In summary, the La-[Zn, Ga] / Nano-HZSM-5 molecular sieve prepared by the technical solution claimed in the present application has high catalytic activity when catalyzing the MTA reaction, as shown in Table 1; compared with comparative examples 1 to 3, the methanol conversion rate and aromatics selectivity of Examples 1-7 are greatly improved, among which the catalytic reaction life and aromatics selectivity of Example 1 reach 52h and 59.3%, respectively, meeting the requirements of high catalytic MTA reaction, indicating that the La-[Zn, Ga] / Nano-HZSM-5 molecular sieve prepared by the technical solution of the present application uses the b-axial diffusion advantage and the dual coupling of the [Zn-O-Re-Ga] quaternary active center and the intrinsic catalytic active center in a coordinated manner, so that the [Zn-O-Re-Ga] quaternary active center in the formed catalytic system enhances the CH bond activation ability in the MTA reaction and more efficiently adsorbs methanol molecules. The coupling effect of rare earth additives and Zn / Ga metals promotes the rapid diffusion of aromatic products and the spatial confinement effect of carbon deposit precursors, effectively improving the selectivity and catalytic reaction life of BTX, and has the effect of efficiently utilizing coal-based methanol to produce high-value-added aromatic products.

[0122] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a bifunctional catalyst with controllable surface active sites, characterized in that: The following steps are involved: S1. Preparation of nano-scale H-ZSM-5 catalyst: Sodium metaaluminate and sodium hydroxide are used as aluminum source and alkali source, respectively, and are uniformly mixed with deionized water, tetrapropylammonium hydroxide and a composite template agent, and then tetraethyl silicate is added as a silicon source to obtain a synthetic solution. After stirring and aging, the aged synthetic solution is transferred to a crystallization kettle for crystallization, and then centrifuged and dried to obtain a nano-scale Na-ZSM-5 molecular sieve, which is placed in an NH4Cl solution and heated with stirring for ion exchange, and then dried and calcined to obtain a nano-scale H-ZSM-5 catalyst; S2. Preparation of a highly dispersed Zn / H-ZSM-5 bifunctional catalyst: A Zn metal impregnation solution was prepared using zinc nitrate hexahydrate as a Zn source, which was added to the nanoscale H-ZSM-5 catalyst prepared in S1 above and ultrasonically impregnated to disperse the Zn metal, followed by drying to obtain a highly dispersed Zn / H-ZSM-5 bifunctional catalyst; S3 introduces an acidic site modifier: configuring an acidic site modifier ion exchange solution and adding it to the highly dispersed Zn / H-ZSM-5 bifunctional catalyst for ion exchange reaction, and drying after completion of the ion exchange reaction to obtain a nano-scale highly dispersed acidic Zn / H-ZSM-5 bifunctional catalyst; S4. Introducing a rare earth element modifier: Using hexahydrated rare earth metal nitrate as a rare earth element modifier, adding deionized water to obtain a rare earth metal ion exchange solution, adding the rare earth metal ion exchange solution to the nano-scale highly dispersed acid-adjusted Zn / H-ZSM-5 bifunctional catalyst to carry out an ion exchange reaction, and then drying to obtain a nano-scale highly dispersed rare earth-doped acid-adjusted Zn / H-ZSM-5 bifunctional catalyst.

2. The method for preparing a bifunctional catalyst with controllable surface active sites according to claim 1, wherein: The composite template agent includes any combination of tetrapropylammonium hydroxide-n-propylamine, tetrapropylammonium hydroxide-n-butylamine and tetrapropylammonium hydroxide-polyethylene glycol.

3. The method for preparing a bifunctional catalyst with controllable surface active sites according to claim 2, characterized in that: The composite template agent is a combination of tetrapropylammonium hydroxide and n-propylamine, wherein the mass ratio of tetrapropylammonium hydroxide to n-propylamine is 1:(1-3).

4. The method for preparing a bifunctional catalyst with controllable surface active sites according to claim 1, wherein: The synthetic liquid comprises the following components in a molar ratio: 0.4-0.5 of tetrapropylammonium hydroxide, 0.4-1.5 of n-propylamine, 1 of ethyl silicate, 0.005-0.04 of aluminum oxide, 0.06-0.1 of sodium oxide and 400-500 of water; The crystallization kettle is a crystallization kettle with a polytetrafluoroethylene lining, the crystallization temperature is 175-195° C., and the crystallization time is 24-48 hours.

5. The method for preparing a bifunctional catalyst with controllable surface active sites according to claim 1, wherein: The conditions for ultrasonic impregnation of Zn metal in step S2 are: adding Zn metal impregnation solution dropwise according to the impregnation amount of catalyst: Zn metal impregnation solution = 1g: 1ml; and placing the sample after the dropwise addition in an ultrasonic instrument at 60°C for ultrasonic impregnation for 1-2h.

6. The method for preparing a bifunctional catalyst with controllable surface active sites according to claim 1, wherein: The acid site regulator includes a compound of one or more of gallium nitrate hexahydrate, nickel nitrate hexahydrate or cobalt nitrate hexahydrate and deionized water.

7. The method for preparing a bifunctional catalyst with controllable surface active sites according to claim 1, wherein: The ion exchange introduction conditions of the acidic site regulator are as follows: adding the rare earth metal impregnation solution into a beaker at an impregnation ratio of 1g:30ml of the catalyst and rare earth metal impregnation solution; and placing the beaker in an 80°C water bath for ion exchange for 3-4 hours with the top stirring device set to 300-400rpm / min.

8. The method for preparing a bifunctional catalyst with controllable surface active sites according to claim 1, wherein: The rare earth element modifier is one or more of lanthanum nitrate hexahydrate, cerium nitrate hexahydrate or yttrium nitrate hexahydrate.

9. The method for preparing a bifunctional catalyst with controllable surface active sites according to claim 1, wherein: The conditions for introducing rare earth elements by ion exchange are as follows: the catalyst and rare earth element impregnation solution are added to a beaker at a ratio of 1g:30ml; and the top stirring device is set to 300-400rpm / min, and the ion exchange is carried out in a water bath at 80°C for 3-4h.

10. Application of a bifunctional catalyst with regulatable surface active sites, characterized in that: 0.6-0.9 g of the nano-scale highly dispersed rare earth doped acid-adjusted Zn / H-ZSM-5 bifunctional catalyst was filled into a fixed bed reactor, the methanol flow rate was controlled to be 0.01-0.04 ml / min, and the reaction was carried out at 425-475 ° C. The mass space velocity was 1-3 h -1 .

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