CN108946756B

CN108946756B - Hierarchical pore EUO structure molecular sieve and synthesis method thereof

Info

Publication number: CN108946756B
Application number: CN201810945479.4A
Authority: CN
Inventors: 王志光; 王建青; 李进; 王炳春
Original assignee: China Catalyst New Material Co ltd
Current assignee: China Catalyst New Material Co ltd
Priority date: 2018-08-20
Filing date: 2018-08-20
Publication date: 2020-04-07
Anticipated expiration: 2038-08-20
Also published as: CN108946756A

Abstract

The invention discloses a hierarchical pore EUO structure molecular sieve and a synthesis method thereof, which are characterized in that a long-chain silane compound is used as a crystallization auxiliary agent, biquaternary ammonium salt with a bihexatomic heterocyclic group substituted alkane structure is used as an organic template agent, and silicon-aluminum sol is crystallized and synthesized at the temperature rise rate of 2-20 ℃/h to the target temperature, wherein the target crystallization synthesis temperature is 150-190 ℃; and then removing the organic template agent through separation, washing, drying and roasting to obtain the hierarchical porous EUO structural molecular sieve raw powder, and then sequentially performing ammonium ion exchange, drying and roasting to obtain the H-shaped hierarchical porous EUO structural molecular sieve. The zeolite molecular sieve provided by the invention has a hierarchical pore structure, the range of the silica-alumina ratio of the product is wide, the grain size is small, the relative crystallinity is high, and the hydrothermal stability is strong; the reaction evaluation shows good xylene isomerization activity and selectivity, thereby having good industrial application prospect.

Description

Hierarchical pore EUO structure molecular sieve and synthesis method thereof

Technical Field

The invention relates to a hierarchical porous EUO structure molecular sieve and a synthesis method thereof, belonging to the field of inorganic material synthesis.

Background

The EUO type topological structure molecular sieve crystal structure is provided with a one-dimensional ten-membered ring channel with the diameter of 0.54nm multiplied by 0.41nm in the [100] direction, and two sides of the ten-membered ring channel are also provided with a twelve-membered ring side pocket with the depth of 0.81nm multiplied by 0.68nm multiplied by 0.58 nm. EU-1, ZSM-50 and TPZ-3 molecular sieves all have EUO type topological structures, wherein the EU-1 molecular sieve is a relatively wide molecular sieve researched in recent years, and due to the special pore channel structure and the acidic characteristic of the EUO type molecular sieve, the EUO type molecular sieve is used as a bifunctional catalyst prepared from an acidic component of a carbon octaarene isomerization catalyst, has good activity and selectivity in the carbon octaarene hydroisomerization and benzene isopropylation catalytic reaction, and is known as the first choice of a new generation of xylene isomerization catalytic materials.

US4537754 discloses a hydrothermal crystallization synthesis method of EU-1 type molecular sieve, which takes alkylated derivative of polymethylene α -omega-diamine ion or precursor thereof as template agent, and prepares the EUO type molecular sieve by uniformly mixing silica-alumina source, alkali metal, template agent, seed crystal and the like and then carrying out hydrothermal crystallization, US65144479 discloses a hydrothermal synthesis method of EUO type molecular sieve, wherein silica-alumina source, alkali metal, template agent, seed crystal and the like are used as template agentAnd (3) carrying out hydrothermal treatment after uniform mixing, wherein the crystal grain size is reduced by adopting ultrasonic treatment, and the obtained crystal grain size is within 5 mu m. Lixiafeng et al (same or different seed crystal effect in EU-1 molecular sieve synthesis, journal of Petroleum institute (petroleum processing) 2006: 93-95) investigated same or different seed crystal effect in EU-1 molecular sieve synthesis. The addition of the homogeneous seed crystal can improve the crystallinity of the product and shorten the crystallization time to 1-2 days. The obtained EU-1 molecular sieve was oval in shape and 2.0. mu. m.times.1.0. mu.m in size. Liaofeng et al (Rapid synthesis and characterization of EU-1 molecular sieves, petrochemical, 2007,36(8):794-₂-Na₂O-Al₂O₃-SiO₂-H₂The hydrothermal synthesis time can be shortened to 28 hours by the method for quickly synthesizing the EU-1 molecular sieve with high crystallinity in the O system. The EU-1 molecular sieve obtained by the method is an aggregate with the particle size of 1-5 mu m, and is formed by aggregating sub-particles with the particle size of 0.3-0.8 mu m. The US6377063 patent discloses a process for the synthesis of molecular sieves with EUO structure, using as structure directing agent at least one alkylated derivative of methylenediamine ions which is safer and cheaper than the templating agents or precursors of templating agents disclosed in the prior art, reducing the production costs and being safer and more environmentally friendly.

The preparation method of the molecular sieve with the EUO structure disclosed by the above documents mainly comprises a traditional hydrothermal method and a solid-phase in-situ method, but the molecular sieve has basically consistent structure, generally larger particle size which is in micron order, is easy to generate mixed crystals, has serious limitation on the catalytic life of the molecular sieve, and the product yield needs to be improved. The molecular sieve with the multilevel pore channel EUO structure shortens the molecular diffusion distance, so that reaction products are easier to diffuse from active sites to the outer surface, the formation of coking is inhibited, and the service life of the catalyst is prolonged.

Disclosure of Invention

The invention aims to solve the technical problems in the prior art and provides a hierarchical pore EUO structure molecular sieve and a synthesis method and application thereof, wherein the hierarchical pore EUO structure molecular sieve is used as a catalyst active component or a carrier to improve the catalytic reaction activity, reduce the probability of reaction inactivation and prolong the service life of the catalyst; the synthesis method utilizes long-chain silane compound as crystallization auxiliary agent and uses bisMethod for synthesizing hierarchical porous EUO structure molecular sieve by using biquaternary ammonium salt of hexatomic heterocyclic group substituted alkane as organic template agent, and molecular sieve with pore distribution structure is beneficial to C₈Acidic component of aromatic isomerization reaction.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention firstly provides a method for synthesizing a hierarchical pore EUO structure molecular sieve, which comprises the following steps:

(1) preparing mixed sol: alkali source, silicon source, aluminum source, long-chain organosilane LCS, biquaternary ammonium salt template agent OSDA and deionized water H₂Mixing O uniformly to obtain mixed sol; mixing with Na as alkali source₂O, silicon source is SiO₂Calculated by Al as the aluminum source₂O₃Calculated by the molar ratio of each material as Na₂O：SiO₂：Al₂O₃：LCS：OSDA：H₂O＝(0.02～0.2)：1.0：(0.001667～0.05)：(0.003～0.03)：(0.05～0.5)：(10～50)；

(2) And (3) crystallization: placing the mixed sol obtained in the step (1) in a crystallization kettle, crystallizing for 24-168 hours at the temperature of 150-200 ℃, separating out a solid product after complete crystallization, and removing the organic template agent from the solid product after washing, drying and roasting the solid product to obtain raw powder of the molecular sieve with the hierarchical pore EUO structure;

(3) ion exchange: carrying out ammonium ion exchange on the raw powder of the molecular sieve with the hierarchical pore EUO structure obtained in the step (2) to remove Na⁺Drying and roasting the product to obtain the H-shaped porous EUO structure molecular sieve;

in the step (1), the bis-quaternary ammonium salt template agent OSDA is selected from compounds containing bis-hexahydric heterocyclic group substituted alkane, and the structural formula is shown as chemical formula I, chemical formula II and chemical formula III:

n is 4-12 formula I;

n is 4-12 chemical formula II;

n is 4-12 chemical formula III;

the porous EUO structure molecular sieve formed in the step (3) comprises any one of an EU-1 molecular sieve, a TPZ-3 molecular sieve and a ZSM-50 molecular sieve, and the mole ratio of silicon oxide/aluminum oxide in the molecular sieve is within the range of 20-600.

In the above technical scheme, the synthesis method specifically comprises the following steps:

(1) preparing mixed sol: dissolving the long-chain organosilane LCS in the proportion into methanol or ethanol, and stirring and dispersing to form a solution of the long-chain organosilane LCS; then adding the alkali source, the silicon source, the biquaternary ammonium salt template agent OSDA and the deionized water H into the solution of the long-chain organosilane LCS according to the proportion₂O, stirring for 5-10 hours at the temperature of 25-60 ℃ to obtain a silicon source mixed solution; adding the aluminum source in the proportion into the silicon source mixed solution at the temperature of 25-80 ℃, violently stirring for 30-180 min, and standing and aging at room temperature for 2-24 hours to obtain mixed sol;

(2) and (3) crystallization: placing the mixed sol obtained in the step (1) in a crystallization kettle, crystallizing at a target temperature of 150-190 ℃, wherein the initial heating rate is 2-20 ℃/h, heating to the target temperature, crystallizing at a holding temperature, the heating time is 6.5-85 hours, the crystallization time is 24-168 hours, after crystallization is completed, centrifugally separating out a solid product, repeatedly washing the solid product with deionized water to neutrality, drying at 100-130 ℃ for 12-48 hours, roasting at 500-600 ℃ for 2-10 hours after drying, and removing an organic template agent to obtain raw powder of the hierarchical pore EUO structure molecular sieve;

(3) ion exchange: putting the raw powder of the molecular sieve with the hierarchical pore EUO structure obtained in the step (2) into NH₄ ⁺Exchanging for 2-12 hours at 80-120 ℃ in the ion solution, then centrifuging or filtering to separate out an ion exchange product, and reacting the ion exchange product with deionized waterWashing to be neutral; repeat the above NH₄ ⁺And (3) carrying out ion exchange for 1-3 times, drying at 100-130 ℃ for 12-48H, and roasting at 400-600 ℃ for 2-10H to obtain the H-shaped hierarchical pore EUO structure molecular sieve.

In the above technical scheme, in the step (1), the alkali source is NaOH or Na₂O₂、KOH、Na₂CO₃、NaHCO₃Any one, two or more of them are mixed in any proportion to form a mixture.

In the above technical scheme, in the step (1), the silicon source is a mixture of any one, two or more of water glass, silica sol, ethyl silicate, methyl silicate, sodium silicate, silicic acid, diatomite, silica gel microspheres or white carbon black mixed in any proportion.

In the above technical scheme, in the step (1), the aluminum source is any one, two or more of pseudo-boehmite, aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum hydroxide, aluminum isopropoxide and aluminum sol mixed in any proportion.

In the above technical scheme, in the step (1), the long-chain organosilane LCS is a mixture formed by mixing any one, two or more than two of hexadecyl trimethoxy silane, hexadecyl triethoxy silane, octadecyl trimethoxy silane, octadecyl triethoxy silane, octadecyl methyl dimethoxy silane and octadecyl dimethyl methoxy silane in any proportion.

In the above technical solution, in the step (1), the bis-quaternary ammonium salt template OSDA is specifically 1, 6-bis (N-methylpiperidinium) hexane, 1, 4-bis (N-methylpiperidinium) butane, 1, 5-bis (N-methylpiperidinium) pentane, 1, 7-bis (N-methylpiperidinium) heptane, 1, 8-bis (N-methylpiperidinium) octane, 1, 4-bis (N-methylpiperazinium) butane, 1, 5-bis (N-methylpiperazinium) pentane, 1, 6-bis (N-methylpiperazinium) hexane, 1, 8-bis (N-methylpiperazinium) octane, 1, 4-bis (N-methylmorpholinium) butane, 1, 5-bis (N-methylmorpholinium) pentane, Any one or more of 1, 6-bis (N-methylmorpholinium) hexane and 1, 8-bis (N-methylmorpholinium) octane, preferably any one, two or more of 1, 6-bis (N-methylpiperidinium) hexane, 1, 6-bis (N-methylpiperazinium) hexane and 1, 6-bis (N-methylmorpholinium) hexane in any proportion.

In the above technical solution, in the step (3), the NH is₄ ⁺The ionic solution refers to an aqueous solution of ammonium salt, wherein the ammonium salt is a mixture formed by mixing any one, two or more than two of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium carbonate and ammonium acetate in any proportion; the concentration of ammonium salt in the aqueous solution of ammonium salt is 0.1-5.0 mol/L, preferably 0.2-2.0 mol/L.

In the above technical scheme, in the step (3), the raw powder of the hierarchical pore EUO structure molecular sieve and NH are₄ ⁺The solid-liquid mass ratio of the ionic solution is 1: (5-50).

The invention also provides an H-type hierarchical pore EUO structure molecular sieve synthesized by the synthesis method, which comprises any one of an EU-1 molecular sieve, a TPZ-3 molecular sieve and a ZSM-50 molecular sieve, preferably the EU-1 molecular sieve; the mole ratio of silicon oxide/aluminum oxide in the molecular sieve is within the range of 20-600.

The technical scheme of the invention has the advantages that:

1. the EUO molecular sieve synthesized by the method has high relative crystallinity and small grain size, has a microporous-mesoporous-macroporous multilevel pore channel structure, is favorable for the diffusion of reactant molecules on the active site of the catalyst, increases the external specific surface area, improves the diffusion performance of the molecular sieve, and further improves the catalytic activity.

2. The EUO molecular sieve synthesized by the method adopts a novel biquaternary ammonium salt containing double hexahydric heterocyclic groups to substitute alkane as a template agent, overcomes the defect that high-silicon EU-1 zeolite cannot be obtained in the prior art, has good synthesis repeatability, wide feeding range, less synthesis condition limitation, wide silicon-aluminum ratio range of products and strong hydrothermal stability, and is favorable for solving the problems of low silicon-aluminum ratio and low single-kettle yield of EU-1 zeolite synthesis products reported in the prior art.

3. The long-chain organosilane is added in the synthesis process, so that the electrostatic repulsive force between initial particles is increased, and the particles are not easy to agglomerate. Methoxy or ethoxy can replace non-skeleton bridge hydroxyl on the surface of the micelle, thereby reducing the attraction among particles, dispersing the formed aggregation crystal nucleus in the solution and reducing the tendency of aggregation. The hydrophilic hydration of methanol or ethanol also accelerates the nucleation process, increasing the relative number of available seeds, and thus making the molecular sieve smaller in grain size.

4. The invention not only optimizes the synthesis process, but also ensures that the prepared zeolite molecular sieve has special structural morphology, improves the structural characteristics of the product, has simple raw materials and process for synthesis and is beneficial to industrial implementation.

Drawings

FIG. 1 is an X-ray diffraction (XRD) pattern of the molecular sieve prepared in comparative example 1 of the present invention.

FIG. 2 is an X-ray diffraction (XRD) pattern of the molecular sieve prepared in example 1 of the present invention.

Fig. 3 is a Scanning Electron Microscope (SEM) photograph of the molecular sieve prepared in comparative example 1 of the present invention.

FIG. 4 is a Scanning Electron Microscope (SEM) photograph of the molecular sieve prepared in example 1 of the present invention.

Detailed Description

The following detailed description of the embodiments of the present invention is provided, but the present invention is not limited to the following descriptions:

the meso-macroporous volume and total pore volume of the molecular sieve were determined in each of the comparative examples as follows: the total pore volume of the molecular sieve was determined from the adsorption isotherm according to the RIPP151-90 standard method (published by scientific Press, 1990, compiled in methods of petrochemical analysis (RIPP test methods), Yankee, etc.), the micropore volume of the molecular sieve was determined from the adsorption isotherm according to the T-plot method, and the meso-macropore volume was obtained by subtracting the micropore volume from the total pore volume.

In each of the comparative examples and examples, the crystallinity and nSiO2/nAl2O3 were determined using an X-ray diffractometer of the Dutch PANalytical type under the experimental conditions CuK α radiation (0.1541nm), tube voltage 40kV and tube current 40 mA. relative crystallinity, according to the SH/T0340-92 standard method (compiled Standard of chemical industry, published by Chinese standards Press, 2000).

Comparative example 1:

EU-1 molecular sieves were synthesized according to the examples of patent CN 01121442: solution I consisting of silicon and a structuring agent precursor was prepared by diluting 3530g of benzyldimethylamine (98%) and 3260g of benzylchloride (99%) in 42.92g of water, followed by the addition of 38.45g of SiO2 sol (Ludox HS40, 40% SiO 2). Solution II was then prepared by dissolving 0.610g of solid sodium hydroxide (99%) and 0.496g of solid sodium aluminate (46% A12O3, 33% Na2O) in 5.36g of water. Solution I was added to solution II with stirring, followed by the addition of 5.36g of water. Mix them until homogeneous. The resulting mixture was allowed to react in a 125ml autoclave with stirring at 180 ℃ under autogenous pressure for 3 days. After cooling, the product was filtered, washed with deionized water, dried at 120 ℃ for 12 hours, and calcined at 550 ℃ for 4 hours to obtain the EU-1 molecular sieve, the crystallinity was set to 90%, and the relative crystallinity was calculated for the other samples below and this sample as a reference.

10g of molecular sieve raw powder is placed in 100ml of NH with the concentration of 0.5mol/L₄NO₃Exchanging the solution at 90 ℃ for 4 h; then filtering to separate the ion exchange product, and repeating the above NH₄ ⁺And (3) repeatedly washing the ion exchange product to be neutral by using deionized water for 2 times in the ion exchange process, then drying at 120 ℃ for 12 hours, and roasting at 550 ℃ for 4 hours after drying to obtain the H-type EU-1 molecular sieve which is marked as VS-1.

Comparative example 2:

EU-1 molecular sieves were synthesized according to the example of patent CN 201610102491: 6.0g of deionized water, 0.22g of sodium hydroxide, 0.5g of hexamethonium bromide, 1.2g of white carbon black (solid content: 92%, the same applies below), and 0.14g of sodium metaaluminate (Al)₂O₃41 wt.%), stirring for 2 hours, placing in a reaction kettle, and carrying out first aging: the aging temperature is 80 ℃, and the aging time is 24 h. After aging, 3 mol% of gamma-glycidol ether oxypropyl trimethoxysilane as a silicon source is added. And then carrying out secondary aging: the aging temperature is 100 ℃, and the aging time is 12 h. Crystallizing at 170 ℃ for 60h after aging, filtering, washing, drying at 120 ℃ for 12h, heating to 550 ℃, and roasting for 4h to obtain EU-1 molecular sieve raw powder with the relative crystallinity of 95%.

10g of raw powder of the molecular sieve is placed in 100ml of NH4NO3 solution with the concentration of 0.5mol/L, and exchange is carried out for 4h at the temperature of 90 ℃; and then filtering and separating an ion exchange product, repeating the NH4+ ion exchange process for 2 times, repeatedly washing the ion exchange product with deionized water until the ion exchange product is neutral, then drying the ion exchange product at 120 ℃ for 12 hours, and roasting the ion exchange product at 550 ℃ for 4 hours to obtain the H-type EU-1 molecular sieve which is marked as VS-2.

Comparative example 3:

EU-1 molecular sieves were synthesized according to the example of patent CN 201610255048: taking 1.35mol of dimethyloctadecyl [3- (trimethoxysilyl) propyl ] ammonium chloride, dissolving the mixture in 750ml of 16% methanol aqueous solution, adding 300g (5mol) of silicon dioxide with the specific surface area of 200m2/g and the particle size of 12nm after complete dissolution, pouring the mixture into a 2000ml three-neck flask, refluxing and stirring the mixture for 10 hours at 100 ℃, washing the obtained solid with ethanol, drying the solid at 100 ℃, and grinding the solid to obtain silicon dioxide powder with silanized surface.

Adding 2.6g sodium hydroxide into 10ml distilled water, stirring for clarification, adding 2.0g sodium metaaluminate (Al)₂O₃41 wt%, adding 17.2g of hexamethyl ammonium bromide after complete dissolution for dissolution and clarification, then adding 0.8g of sodium fluoride and 0.8g of ammonium nitrate, adding 0.4g of seed crystal after dissolution and clarification for dissolution for 20min, finally adding 42.2g of the silicon dioxide powder with silanized surface, and stirring for 4h at room temperature to obtain the silicon-aluminum gel.

And (3) putting the obtained silicon-aluminum gel into a sealed reaction kettle with a polytetrafluoroethylene lining, pre-crystallizing for 16h at 100 ℃, and then heating to 160 ℃ for crystallizing for 12 days. And taking out the obtained solid product, washing the solid product to be neutral by using distilled water, drying the solid product for 12h at the temperature of 120 ℃, heating the solid product to 550 ℃, and introducing oxygen for roasting the solid product for 4h to obtain mesoporous EU-1 molecular sieve raw powder with the relative crystallinity of 92 percent.

10g of raw powder of the molecular sieve is placed in 100ml of NH4NO3 solution with the concentration of 0.5mol/L, and exchange is carried out for 4h at the temperature of 90 ℃; then filtering to separate the ion exchange product, and repeating the above NH₄ ⁺And (3) repeatedly washing the ion exchange product to be neutral by using deionized water for 2 times in the ion exchange process, drying at 120 ℃ for 12 hours, and roasting at 550 ℃ for 4 hours after drying to obtain the H-type EU-1 molecular sieve which is marked as VS-3.

Example 1:

a synthetic method of a hierarchical pore EUO structure molecular sieve comprises the following steps:

(1) preparing mixed sol: weighing quantitative hexadecyl trimethoxy silane, dissolving the hexadecyl trimethoxy silane in methanol to form a solution, and stirring and dispersing to form a hexadecyl trimethoxy silane solution; then, to the solution of hexadecyltrimethoxysilane, NaOH, water glass, 1, 6-bis (N-methylpiperidinium) hexane and deionized water H were added in quantitative amounts₂O, obtaining a silicon source mixed solution; adding a certain amount of pseudo-boehmite into the silicon source mixed solution at the temperature of 60 ℃, violently stirring for 90min, and standing and aging at room temperature for 12 hours to obtain mixed sol; the mixed sol is used as a crystallization precursor mixture and comprises the following components:

Na₂O:SiO₂:Al₂O₃:LCS:OSDA:H₂O＝0.12:1:0.0211:0.0042:0.08:15。

(2) and (3) crystallization: and (2) placing the mixed sol obtained in the step (1) into a crystallization kettle, crystallizing at 170 ℃, wherein the heating rate of the mixed sol from room temperature to 170 ℃ is 5 ℃/h, the crystallization time is 72 hours, after the mixed sol is completely crystallized, taking out and rapidly cooling to room temperature, centrifugally separating out a solid product, repeatedly washing the solid product to be neutral by using deionized water, then drying for 24 hours at 120 ℃, roasting for 6 hours at 550 ℃ after drying, and removing the organic template agent to obtain the raw powder of the hierarchical pore EUO structure molecular sieve. The types of the selected silicon source, the aluminum source, the long-chain organosilane and the biquaternary ammonium salt template agent, the feeding proportion, the heating rate, the crystallization temperature, the crystallization time, the silicon-aluminum ratio of the product and the physicochemical characteristics are shown in tables 2 and 3.

(3) Ion exchange: placing 10g of the raw powder of the hierarchical porous EUO structure molecular sieve obtained in the step (2) in 100ml of NH with the concentration of 0.5mol/L₄Exchanging for 4 hours at 90 ℃ in a Cl solution; then filtering and separating out an ion exchange product, and repeatedly washing the ion exchange product to be neutral by using deionized water; repeat the above NH₄ ⁺Ion exchange process for 2 times, drying at 120 deg.C for 12 hr, and calcining at 550 deg.C for 4 hr to obtain H-type hierarchical porous EUO structure molecular sieve (EUO-1).

The relative crystallinity of the raw powder of the molecular sieve with the hierarchical pore EUO structure obtained by the invention is 102%.

The EU-1 molecular sieve product obtained by the invention has a micropore-mesopore hierarchical pore structure, and the size range of mesopore channels is 2-15 nm.

The XRD characterization of the sample 1(EUO-1) prepared in example 1 by the invention is to confirm that the EU-1 molecular sieve is the typical XRD spectrum (as shown in figure 2) with the adopted instrument of PANalytical X' Pert type X-ray diffractometer, copper target, K α radiation source instrument working voltage of 40kv and working current of 40 mA., as represented by sample 1, and the main diffraction peak position and peak intensity of 2 theta at 5-50 degrees are shown in Table 1. other sample data result is that compared with sample 1, the diffraction peak position and shape are the same, and the relative peak intensity fluctuates within the range of +/-5% according to the change of synthesis conditions, which shows that the synthesized product has the characteristics of EU-1 molecular sieve structure, and the XRD spectrum is analyzed as shown in figure 2, and the diffraction peaks at 2 theta of 7.93 degrees, 8.70 degrees, 19.10 degrees, 20.55 degrees, 22.20 degrees and 27.20 degrees are the main characteristic peaks.

TABLE 1

SEM image analysis of sample 1 prepared in example 1 of the present invention shows that EU-1 molecular sieve is platelet-shaped nanocrystal aggregation morphology, and BET analysis shows that the specific surface area is 547.8m²Per g, the mesoporous volume is 0.55cm³(g), the average size of mesopores is 8.7 nm.

Examples 2 to 8:

the method is the same as that of the embodiment 1, and parameters such as types of selected silicon source, aluminum source, long-chain organosilane and biquaternary ammonium salt template agent, feeding ratio, heating rate, crystallization temperature, crystallization time and the like are selected, referring to table 2; the physical and chemical properties of the products EUO-2-EUO-8 prepared in examples 2-8 are shown in Table 3:

table 2: selection of parameters in the EU-1 molecular sieves Synthesis procedure in the examples

Table 3: example and comparative example physical and chemical properties of EU-1 molecular sieve synthesized product

Application examples

The EUO-1 to EUO-5 products obtained in examples 1 to 5 and the VS-1 to VS-3 products obtained in comparative examples were subjected to evaluation analysis for catalytic application:

the catalytic reaction is carried out on a fixed bed high-pressure micro-reaction device, and m-xylene (MX) is used as a reaction raw material. Respectively measuring 2ml of particles obtained after tabletting of the molecular sieves of the embodiment and the comparative example as catalysts, mixing the particles with quartz sand with the same volume, filling the mixture into a constant temperature area of a reaction tube, respectively supporting two ends of a catalyst bed layer by the quartz sand, and filling the outer ends of the quartz sand by proper amount of quartz cotton to prevent the catalyst from losing. Catalyst H at 350 ℃ of 100ml/min₂The reaction was carried out after 1 hour of activation under a gas stream.

The reaction conditions are as follows: 390 ℃, 0.9MPa, the volume ratio of hydrogen to oil of 800:1 and the feeding mass space velocity of 5.0h^-1. The products of the reaction were analyzed by Agilent model 7820 gas chromatography using a FID detector. The catalytic evaluation results are shown in table 4.

Evaluation indexes are as follows: according to the activity (m-xylene conversion C)_MX/％And p-xylene PX equilibrium content value PX/Sigma X/%) and selectivity (PX/OX ratio, xylene loss ratio X)_L/%) catalyst performance was evaluated.

The relevant calculation formula based on the mass content of the components is defined as follows:

ΣX＝PX+OX+MX

PX equilibrium content value: PX/Sigma X is PX/(PX + MX + OX). times.100%

OX equilibrium content value: OX/Σ X is OX/(PX + MX + OX). times.100%

MX equilibrium content value: MX/Sigma X is MX/(PX + MX + OX). times.100%

Table 4: evaluation results of MX isomerization of molecular Sieve catalyst

Example numbering	Molecular sieves	C_MX/％	PX/ΣX/％	OX/ΣX/％	PX/OX ratio	X_L/％
							Example 9	EUO-1	45.4	23.7	19.1	1.2	2.6
Example 10	EUO-2	46.2	23.7	18.5	1.3	4.0
							Example 11	EUO-3	46.3	23.8	19.0	1.3	3.5
Example 12	EUO-4	47.1	23.6	19.7	1.2	3.8
							Example 13	EUO-5	46.1	23.1	18.5	1.3	4.5
Example 14	VS-1	45.1	13.5	6.4	2.1	25.2
							Example 15	VS-2	30.7	13.4	10.0	1.3	7.4
Example 16	VS-3	44.6	14.3	14.3	1.0	16.0

As can be seen from Table 4, the EUO-1 to EUO-5 molecular sieves provided in the examples of the present invention were prepared as catalysts, and MX conversion (C) in an isomerization reaction using MX as a raw material_MXThe concentration of the xylene is more than or equal to 45.4 percent, the PX equilibrium content value (PX/Sigma X/%) is more than or equal to 23.1 percent, the thermodynamic equilibrium value is basically reached, and the xylene loss rate (X) is increased_L/％)<5 percent. In contrast, comparative example 1 provided hydrogen EUO molecular sieve VS-1 with a higher MX conversion of 45.1%, but with a PX/Sigma X/% value of only 13.5%, X_LThe/% value reaches 25.2%, which indicates that the side reaction is increased; the MX conversion rate of the hydrogen type EUO molecular sieve VS-2 provided by the comparative example 2 is low and only reaches 30.7 percent, the PX/Sigma X/% value is only 13.4 percent, and X is_LThe/% value reached 7.4%. Comparative example 3 also provided hydrogen EUO molecular sieve VS-3 with a higher MX conversion of 44.6%, a PX/Sigma X/% value of only 14.3%, and X_LThe/% value reached 16.0%, increasing side reactions.

The above comparison shows that the invention is implementedThe H-type multi-stage porous EUO molecular sieve provided by the example has higher PX target product yield, MX conversion rate and lower xylene loss rate (X)_LAnd/%) shows that the hierarchical pore EU-1 molecular sieve synthesized by the embodiment of the invention has better activity and selectivity for C8 aromatic isomerization reaction than the EU-1 molecular sieve provided by the comparative example, the loss of xylene products is reduced, the excellent catalytic performance is derived from the hierarchical pore structure, and the diffusion efficiency of target products to xylene is increased.

The above examples are only for illustrating the technical concept and features of the present invention, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A synthetic method of a hierarchical pore EUO structure molecular sieve comprises the following steps:

the porous EUO structure molecular sieve formed in the step (3) is an EU-1 molecular sieve, and the mole ratio of silicon oxide/aluminum oxide in the molecular sieve is within the range of 20-600.

2. The synthesis method according to claim 1, characterized by comprising in particular the following steps:

(3) ion exchange: putting the raw powder of the molecular sieve with the hierarchical pore EUO structure obtained in the step (2) into NH₄ ⁺Exchanging for 2-12 h at 80-120 ℃ in the ionic solution, then centrifuging or filtering to separate out an ion exchange product, and using the ion exchange productRepeatedly washing the mixture to be neutral by using ionized water; repeat the above NH₄ ⁺And (3) carrying out ion exchange for 1-3 times, drying at 100-130 ℃ for 12-48H, and roasting at 400-600 ℃ for 2-10H to obtain the H-shaped hierarchical pore EUO structure molecular sieve.

3. The synthesis method of claim 2, wherein in step (1), the alkali source is NaOH or Na₂O₂、KOH、Na₂CO₃、NaHCO₃Any one, two or more of them are mixed in any proportion to form a mixture.

4. The synthesis method according to claim 2, wherein in step (1), the silicon source is a mixture of any one, two or more of water glass, silica sol, ethyl silicate, methyl silicate, sodium silicate, silicic acid, diatomaceous earth, silica gel microspheres or white carbon black in any ratio.

5. The method according to claim 2, wherein in the step (1), the aluminum source is one, two or more selected from the group consisting of pseudoboehmite, aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum hydroxide, aluminum isopropoxide and aluminum sol mixed at an arbitrary ratio.

6. The synthesis method according to claim 2, wherein in the step (1), the long-chain organosilane LCS is any one, two or more of hexadecyl trimethoxy silane, hexadecyl triethoxy silane, octadecyl trimethoxy silane, octadecyl triethoxy silane, octadecyl methyl dimethoxy silane and octadecyl dimethyl methoxy silane mixed in any ratio.

7. The synthesis method according to claim 2, wherein in step (1), the bis-quaternary ammonium salt template OSDA is 1, 6-bis (N-methylpiperidinium) hexane, 1, 4-bis (N-methylpiperidinium) butane, 1, 5-bis (N-methylpiperidinium) pentane, 1, 7-bis (N-methylpiperidinium) heptane, 1, 8-bis (N-methylpiperidinium) octane, 1, 4-bis (N-methylpiperazinium) butane, 1, 5-bis (N-methylpiperazinium) pentane, 1, 6-bis (N-methylpiperazinium) hexane, 1, 8-bis (N-methylpiperazinium) octane, 1, 4-bis (N-methylmorpholinium) butane, 1, 5-bis (N-methylmorpholinium) pentane, N-methylpiperazinium, N-methyl-1, 4-, 1, 6-bis (N-methylmorpholinium) hexane, 1, 8-bis (N-methylmorpholinium) octane.

8. The method of claim 2, wherein in step (3), said NH is₄ ⁺The ionic solution refers to an aqueous solution of ammonium salt, wherein the ammonium salt is a mixture formed by mixing any one, two or more than two of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium carbonate and ammonium acetate in any proportion; in the ammonium salt water solution, the concentration of the ammonium salt is 0.1-5.0 mol/L.

9. The synthesis method according to claim 8, wherein in the step (3), raw powder of the molecular sieve with a hierarchical pore EUO structure is mixed with NH₄ ⁺The solid-liquid mass ratio of the ionic solution is 1: (5-50).

10. An H-type hierarchical pore EUO structure molecular sieve synthesized by the synthesis method of any one of claims 1 to 9, wherein the H-type hierarchical pore EUO structure molecular sieve is an EU-1 molecular sieve, and the mole ratio of silicon oxide/aluminum oxide in the molecular sieve is within the range of 20-600.