CN111760590B - High mesoporous HZSM-5@SiO 2 Preparation method of composite molecular sieve - Google Patents

High mesoporous HZSM-5@SiO 2 Preparation method of composite molecular sieve Download PDF

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CN111760590B
CN111760590B CN202010703803.9A CN202010703803A CN111760590B CN 111760590 B CN111760590 B CN 111760590B CN 202010703803 A CN202010703803 A CN 202010703803A CN 111760590 B CN111760590 B CN 111760590B
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季东
程春晖
李红伟
李贵贤
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Lanzhou University of Technology
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Abstract

The invention provides a high mesoporous HZSM-5@SiO 2 The preparation method of the composite molecular sieve comprises the following steps: mixing the mixed solution of alkali metal solution and guide hole agent PDAs, HZSM-5, stirring to obtain slurry, stirring to form gel mixed solution, cooling, filtering, washing and drying to obtain Gao Jiekong deg.C XZSM-5 molecular sieve, mixing with NH 4 NO 3 Mixing the solution, performing ion exchange, drying and roasting for 2-3 hours to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystal, adding a dispersing agent and a silicon source, performing hydrothermal crystallization, and washing, drying and roasting to obtain Gao Jiekong-DEG HZSM-5@SiO 2 And (3) a composite molecular sieve. Gao Jiekong-DEG HZSM-5@SiO prepared by the method 2 The composite molecular sieve has good catalytic performance and carbon deposition resistance in the reactions of isomerization, alkylation and the like.

Description

High mesoporous HZSM-5@SiO 2 Preparation method of composite molecular sieve
Technical Field
The invention belongs to the technical field of composite molecular sieve synthesis, and in particular relates to a high mesoporous HZSM-5@SiO seed 2 A preparation method of a composite molecular sieve.
Background
HZSM-5 has two-dimensional 10-membered ring channels, one of which is a 10-membered ring straight channel and the other is a 10-membered ring channel with Zigzag shape: the pore canal structure is [100 ]]
Figure BDA0002593864860000011
[010]/>
Figure BDA0002593864860000012
Figure BDA0002593864860000013
The phase of the orthorhombic system, pnma,
Figure BDA0002593864860000014
the ZSM-5 molecular sieve provides a large number of access channels for reactants and products and good space restriction for shape selective catalysis by virtue of the special pore structure.
HZSM-5 belongs to an orthorhombic system and a molecular sieve (|Na) with an MFI type structure n (H 2 O) 16 ∣[Al n Si 96-n O 192 ]) The silicon to aluminum ratio can range from 10 up to all silicon Silicalite-1.HZSM-5 molecular sieve structure contains strong acid sites (B acid) and weak acid sites (L acid), and the acid center is an active center for initiating catalytic reaction. The acidic catalytic properties of HZSM-5 are independent of Si atoms, but depend on Al atoms of different oxygen coordination numbers in the framework, low coordination Al atoms (i.e. bidentate [ AlO ] 2 ]Three coordination structure [ AlO 3 ]) Forming an L acid center, highly coordinated Al atoms (i.e., tetradentate H [ AlO ] 4 ]Five-coordination structure H 2 [AlO 5 ]Six-coordinated structure H 3 [A1O 6 ]Forming a B acid center. The conversion between the L acid center and the B acid center can be realized by adjusting the oxygen coordination number of the Al atom, so as to achieve the purpose of changing the catalytic performance.
The shape selective catalytic properties of HZSM-5 molecular sieves make it highly selective in certain reactions, but also make catalytic reactions of molecules of similar or larger size than zeolite molecular sieve mesh size difficult to perform, i.e. molecular diffusion in the reaction is limited, which greatly reduces the reactivity, while zeolite molecular sieves are easily deactivated by carbon deposition in the reaction, and the lifetime is also greatly reduced. The mesoporous zeolite molecular sieve is obtained by introducing mesopores into a microporous molecular sieve structure, and the hierarchical pore channel material has the advantages of the microporous molecular sieve and the mesoporous material, has high hydrothermal stability, strong acidity and a mesoporous structure, and can provide good mass transfer performance while maintaining excellent shape selectivity when used as a catalytic material.
As a simple and efficient mesoporous introduction method, alkali treatment is widely used at present as a means for increasing the external surface area of a molecular sieve and improving diffusion. Fathi et al (Fuel, 2014,116 (6): 529-537) use different alkaline reagents NaOH, na 2 CO 3 And CaCO 3 Treatment of ZSM-5 molecular sieves found, na 2 CO 3 The crystallinity of the treated mesoporous ZSM-5 molecular sieve catalyst is increased, and the mesoporous volume is from 0.101cm 3 The/g is lifted to 0.119cm 3 The acid amount per gram was reduced slightly from 0.8594mmol/g to 0.7587mmol/g. However, the traditional alkali treatment using inorganic alkali such as NaOH and the like as an alkali reagent is difficult to control the desilication rate, so that excessive desilication is easy to cause, on one hand, the introduced mesoporous aperture is larger, and on the other hand, a mesoporous system with concentrated and uniformly distributed aperture is difficult to construct in a molecular sieve crystal phase; on the other hand, excessive desilication can cause severe damage to the framework structure, resulting in disruption of the molecular sieve crystal structure, severely affecting the catalytic effect (j. Mater. Chem.,2006,16 (22): 2121).
Disclosure of Invention
The technical problem to be solved by the invention is to provide HZSM-5@SiO with high mesoporous degree aiming at the defects of the prior art 2 Preparation method of composite molecular sieve, gao Jiekong-DEG HZSM-5@SiO prepared by method 2 The core of the composite molecular sieve has a large number of highly-dispersed and strongly-communicated micro-mesoporous structures, so that the diffusion and the reaction activity of molecules are greatly promoted; at the same time inert SiO 2 The thin shell layer can well inhibit the secondary isomerization reaction of aromatic hydrocarbon, can effectively modulate the pore size of HZSM-5 zeolite, and greatly improves the shape selective catalytic capability of zeolite. The method can accurately control the specific surface area and the pore size of the mesoporous of the catalyst core by modulating the type and the dosage of the guide hole agent PDAs; and the existence of the guide hole agent PDAs can effectively prevent disorder in the desilication process, furthest maintain the inherent property of the catalyst core, and have micro-mesoporous structures and connectivity of different layers. Then, by depositing modifiers of different sizes at the orifice of the Gao Jiekong degree HZSM-5 core, fine tuning thereof can greatly improve the shape selectivity of the reactants and products.
In order to solve the technical problems, the invention adopts the following technical scheme: high mesoporous HZSM-5@SiO 2 The preparation method of the composite molecular sieve comprises the following steps:
s1, mixing and stirring mixed solution of alkali metal solution and guide hole agent PDAs and HZSM-5 to obtain slurry;
the mixed solution of the alkali metal solution and the guide hole agent PDAs is a mixture of alkali metal hydroxide solution and guide hole agent PDAs with the mol ratio of 1 (1-5); the concentration of the alkali metal hydroxide solution is 0.1 mol/L-1 mol/L;
s2, stirring the slurry obtained in the step S1 for 2-6 hours at the temperature of 50-90 ℃ to form gel mixed solution, cooling to room temperature, and filtering, washing and drying to obtain Gao Jiekong-DEG XZSM-5 molecular sieve; x in the Gao Jiekong-degree XZSM-5 molecular sieve represents alkali metal;
s3, mixing Gao Jiekong-degree XZSM-5 molecular sieve obtained in S2 with NH with concentration of 0.5 mol/L-1 mol/L 4 NO 3 Mixing the solutions, performing ion exchange at 80 ℃, drying, and roasting at 550-650 ℃ for 2-3 hours to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystals;
s4, adding a dispersing agent and a silicon source into the Gao Jiekong-DEG HZSM-5 molecular sieve seed crystal obtained in the S3, performing hydrothermal crystallization at 100-200 ℃ for 12-38 h, washing, drying, and roasting at 550-650 ℃ for 2-3 h to obtain Gao Jiekong-DEG HZSM-5@SiO 2 And (3) a composite molecular sieve.
Preferably, the ratio of the mixed solution of the alkali metal solution and the guide agent PDAs in the slurry in S1 to the HZSM-5 is (20-50) mL:1g.
Preferably, the alkali metal hydroxide solution in S1 is a sodium hydroxide solution or a potassium hydroxide solution; the guide hole agent PDAs are anionic surfactants, nonionic surfactants or cationic surfactants.
Preferably, the anionic surfactant is DS - The method comprises the steps of carrying out a first treatment on the surface of the The nonionic surfactant is EDA, DAH, TAEA or DEA; the cationic surfactant is PTA + 、TPA + 、CTA + 、DSA + 、HM 2+ 、HDP + Or BA (A) + ；
The anionic surfactant DS - Molecular formula CH 3 (CH 2 ) 11 OSO 3 - The structural formula is as follows:
Figure BDA0002593864860000031
the molecular formula of the nonionic surfactant EDA is C 2 H 4 (NH 2 ) 2 The structural formula is as follows:
Figure BDA0002593864860000041
the molecular formula of the nonionic surfactant DAH is H 2 N(CH 2 ) 6 NH 2 The structural formula is as follows:
Figure BDA0002593864860000042
the nonionic surfactant TAEA has a molecular formula of N (CH) 2 CH 2 NH 2 ) 3 The structural formula is as follows:
Figure BDA0002593864860000043
/>
the molecular formula of the nonionic surfactant DEA is HN (CH) 2 CH 3 ) 2 The structural formula is as follows:
Figure BDA0002593864860000044
the cationic surfactant PTA + Molecular formula (CH) 3 ) 3 N + C 3 H 7 The structural formula is as follows:
Figure BDA0002593864860000045
the cationic surfactant TPA + Molecular formula N + (C 3 H 7 ) 4 The structural formula is as follows:
Figure BDA0002593864860000046
the cationic surfactant CTA + Molecular formula (CH) 3 ) 3 N + C 12 H 25 The structural formula is as follows:
Figure BDA0002593864860000047
the cationic surfactant DSA + Molecular formula (C) 18 H 37 ) 2 N + (CH 3 ) 3 The structural formula is as follows:
Figure BDA0002593864860000048
the cationic surfactant HM 2+ Molecular formula (CH) 3 ) 3 N + C 6 H 12 N + (CH 3 ) 3 The structural formula is as follows:
Figure BDA0002593864860000051
the cationic surfactant HDP + Molecular formula C 16 H 33 N + C 5 H 5 The structural formula is as follows:
Figure BDA0002593864860000052
the cationic surfactant BA + Molecular formula C 6 H 5 CH 2 N + (CH 3 ) 2 R，R＝C 8 H 17 to C 16 H 33 The structural formula is as follows:
Figure BDA0002593864860000053
preferably, the washing in both S2 and S4 is performed by washing with distilled water multiple times to neutrality.
Preferably, the Gao Jiekong degree XZSM-5 molecular sieve described in S3 is combined with NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL.
Preferably, the dispersant in S4 is n-hexane or n-heptane; the silicon source is Si (OCH) 3 ) 4 、Si(OC 2 H 5 ) 4 Or SiCl 4 。
Preferably, the mass ratio of the Gao Jiekong degree HZSM-5 molecular sieve seed crystal, the dispersing agent and the silicon source in S4 is (1-7): (12-28): (3-38).
Preferably, the Gao Jiekong degree HZSM-5@SiO described in S4 2 The specific surface area of the composite molecular sieve is 276m 2 /g～420m 2 Per g, mesoporous volume of 0.23cm 3 /g～0.45cm 3 The most probable pore diameter is 2 nm-30 nm.
Compared with the prior art, the invention has the following advantages:
1. gao Jiekong-DEG HZSM-5@SiO prepared by the method 2 The core of the composite molecular sieve has a large number of highly-dispersed and strongly-communicated micro-mesoporous structures, so that the diffusion and the reaction activity of molecules are greatly promoted; at the same time inert SiO 2 The thin shell layer can well inhibit the secondary isomerization reaction of aromatic hydrocarbon, can effectively modulate the pore size of HZSM-5 zeolite, and greatly improves the shape selective catalytic capability of zeolite. The method can accurately control the specific surface area and the pore size of the mesoporous of the catalyst core by modulating the type and the dosage of the guide hole agent PDAs; and the existence of the guide hole agent PDAs can effectively prevent disorder in the desilication process, furthest maintain the inherent property of the catalyst core, and have micro-mesoporous structures and connectivity of different layers. Then, by depositing modifiers of different sizes at the orifice of the Gao Jiekong degree HZSM-5 core, fine tuning thereof can greatly improve the shape selectivity of the reactants and products.
2. Gao Jiekong-DEG HZSM-5@SiO prepared by the method 2 Composite molecular sieveThe catalyst has uniformly dispersed mesoporous pores with concentrated pore diameters and penetrating type, so that the contact between the active site of the catalyst and reactant molecules can be effectively improved, and the mass transfer capacity of the catalyst can be improved; and a layer of thin SiO shell is covered on the surface of the crystal 2 The shape selectivity of the catalyst is significantly improved. Compared with the conventional microporous HZSM-5 zeolite, the preparation method of the invention prepares Gao Jiekong degrees HZSM-5@SiO 2 The composite molecular sieve has good catalytic performance and carbon deposition resistance in the reactions of isomerization, alkylation and the like.
The invention is described in further detail below with reference to the drawings and examples.
Drawings
FIG. 1 is a Gao Jiekong degree HZSM-5@SiO prepared in example 1 2 X-ray diffraction pattern of composite molecular sieve.
FIG. 2 is a Gao Jiekong degree HZSM-5@SiO prepared in example 1 2 And (3) nitrogen adsorption and desorption isothermal curves of composite molecular sieve products.
FIG. 3 is a Gao Jiekong degree HZSM-5@SiO prepared in example 1 2 Electron microscope image of composite molecular sieve.
FIG. 4 is a Gao Jiekong degree HZSM-5@SiO prepared in example 1 2 Ammonia gas programmed heating of composite molecular sieve is shown in the drawing.
Table 5 shows Gao Jiekong degree HZSM-5@SiO prepared in example 1 2 Inactivation thermogram of the composite molecule.
Detailed Description
Example 1
Gao Jiekong degree HZSM-5@SiO of this example 2 The preparation method of the composite molecular sieve comprises the following steps:
s1, mixing 100mL of mixed solution of alkali metal solution and guide hole agent PDAs and 5g of HZSM-5, and stirring to obtain slurry;
the alkali metal hydroxide solution is sodium hydroxide solution with the concentration of 0.1 mol/L; the guide hole agent PDAs is cationic surfactant TPA + ；
The cationic surfactant TPA + Molecular formula N + (C 3 H 7 ) 4 The structural formula is as follows:
Figure BDA0002593864860000071
wherein Na is + And TPA + The molar ratio of (2) is 1:1; />
S2, stirring the slurry obtained in the step S1 for 4 hours at the temperature of 80 ℃ to form gel mixed solution, cooling to room temperature, filtering, washing with distilled water for multiple times to neutrality and drying to obtain a Gao Jiekong-DEG NaZSM-5 molecular sieve;
s3, mixing the Gao Jiekong-degree NaZSM-5 molecular sieve obtained in S2 with NH with the concentration of 1mol/L 4 NO 3 Mixing the solutions, performing ion exchange AT 80 ℃, drying, and roasting AT 550 ℃ for 3 hours to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystal named AT-3; the Gao Jiekong-DEG NaZSM-5 molecular sieve and NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL;
s4, adding dispersant (n-hexane) and silicon source (Si (OC) 2 H 5 ) 4 ) Then carrying out hydrothermal crystallization for 12 hours at the temperature of 110 ℃, washing with distilled water for many times to neutrality, drying, and roasting for 3 hours at the temperature of 550 ℃ to obtain Gao Jiekong-DEG HZSM-5@SiO 2 The composite molecular sieve is named as AT-4; the mass ratio of the Gao Jiekong-degree HZSM-5 molecular sieve seed crystal to the dispersing agent to the silicon source is 3:17:24, a step of detecting the position of the base; the Gao Jiekong-degree HZSM-5@SiO 2 The specific surface area of the composite molecular sieve is 276m 2 Per g, mesoporous volume of 0.22cm 3 The pore size of the most probable pore is 4.59nm.
Comparative example 1
HZSM-5@SiOof this comparative example 2 The preparation method of the composite molecular sieve is different from the comparative example 1 in that the slurry in the step S1 does not contain guide hole agent PDAs and the step S4 is not carried out; the method comprises the following steps:
s1, mixing 100mL of sodium hydroxide solution with the concentration of 0.1mol/L and 5g of HZSM-5, and stirring to obtain slurry;
s2 is the same as S2 in the embodiment 1;
s3, the seed crystal of the HZSM-5 molecular sieve is obtained by the same method as in S3 in the embodiment 1 and is named as AT-1.
Comparative example 2
The method for preparing HZSM-5 molecular sieve seed crystal of this comparative example is different from example 1 in that the alkali metal solution and the channeling agent PDAs (TPA) + ) The mixed solution of (2) is replaced by a TPAOH solution, the slurry in S1 does not contain guide hole agent PDAs, and the S4 step operation is not carried out; the method comprises the following steps:
s1, mixing 100mL of TPAOH solution with the concentration of 0.1mol/L and 5g of HZSM-5, and stirring to obtain slurry;
s2 is the same as S2 in the embodiment 1;
s3, the seed crystal of the HZSM-5 molecular sieve is obtained by the same method as in S3 in the embodiment 1 and is named as AT-2.
Comparative example 3
The process for preparing HZSM-5 molecular sieve seeds of this comparative example, which differs from example 1 in that there is no S4 step operation; the method comprises the following steps:
s1 is the same as S1 in the embodiment 1;
s2 is the same as S2 in the embodiment 1;
s3, the seed crystal of the HZSM-5 molecular sieve is obtained by the same method as in S3 in the embodiment 1 and is named as AT-3.
FIG. 1 is a sample of HZSM-5, prepared Gao Jiekong degrees HZSM-5@SiO of example 1 2 The X-ray diffraction patterns of composite molecular sieves (AT-4) and AT-1, AT-2 and AT-3 of comparative examples 1-3, as seen by the figures, all samples exhibited typical MFI topology characteristic diffraction peaks AT 2θ=7-10° and 2θ=22.5-25 °. The intensity of the AT-1 characteristic peak is significantly reduced compared to HZSM-5, because excessive desilication of sodium hydroxide results in severe damage to the crystal structure. The increase in the intensity of the diffraction peak of AT-3 compared to that of AT-1 suggests that the addition of the guide agent PDAs (TPA + ) After that, the framework structure of the HZSM-5 molecular sieve can be effectively improved, the disordered in the desilication process can be effectively prevented by the existence of the guide hole agent PDAs, and the inherent properties of the catalyst core, namely the micro-mesoporous structure and connectivity with different layers, are maintained to the maximum extent. The increase in diffraction peak intensity of single TPAOH treated AT-2 compared to AT-3 further demonstrates TPA + Protective desilication of (a). AT-4 has no characteristic diffraction peak of silica compared with AT-3, and the characteristic diffraction peak intensity of MFI is slightly reduced, which is probably that amorphous silica is highly dispersed on the outer surface of molecular sieve, but the crystal structure is not changed, and meanwhile, inert SiO 2 The thin shell layer can well inhibit the secondary isomerization reaction of aromatic hydrocarbon, can effectively modulate the pore size of HZSM-5 zeolite, and greatly improves the shape selective catalytic capability of the HZSM-5 zeolite.
FIG. 2 is a plot of the feed HZSM-5, prepared Gao Jiekong degrees HZSM-5@SiO from example 1 2 The nitrogen adsorption and desorption isotherms of the composite molecular sieve (AT-4) and AT-1, AT-2 and AT-3 of comparative examples 1-3 are shown in Table 1, which shows the physical characteristic parameters. As can be seen from FIG. 1, besides the adsorption isothermal curves of the raw powder HZSM-5 and AT-2, which are typical microporous materials, the other samples have the composite adsorption isothermal curves of the type I and the type IV, which indicates that mesoporous structures are formed in AT-1, AT-3 and AT-4. At p/p 0 >0.4, the hysteresis loops of AT-3 and AT-4 belong to the H2 type compared to the hysteresis loop H3 type of AT-1, which indicates that the mesopores in AT-1 are irregularly shaped, while the mesopores of AT-3 and AT-4 are more concentrated and ordered. As is clear from Table 1, the specific surface area of AT-4 was reduced to 276m as compared with AT-1 2 Per g, essentially of thin-shell SiO coating the surface of the molecular sieve 2 As a result, the core of the catalyst is not affected; at the same time, the pore volume and the most probable pore diameter of the mesoporous are increased by nearly one time compared with HZSM-5, respectively to 0.22cm 3 And/g and 4.59nm, which greatly improves the diffusion path, greatly promotes the diffusion and the reactivity of molecules and reduces the carbon deposition rate.
TABLE 1 physical Property parameters of HZSM-5 and AT-1 to AT-4
Figure BDA0002593864860000091
FIG. 3 is a sample of HZSM-5, prepared Gao Jiekong degrees HZSM-5@SiO of example 1 2 Electron microscopy images of composite molecular sieves (AT-4), AT-1, AT-2, and AT-3 of comparative examples 1-3; it is clear from the figure that, unlike the original powder HZSM-5, the surface is smooth, the grains are complete, the AT-1 surface is rough, and a large number of deeper holes exist.The surface also becomes smooth compared to AT-1, the in vivo appearance of dense and uniform bright spots of AT-3 due to the guiding agent TPA + The ionic radius is greater than the micropore size of the molecular sieve, such that TPA + Has the function of protecting surrounding Si from dissolution, and Na with small radius + The ions do not have protective effect, resulting in OH - More easily attack and dissolve to form mesoporous. Thus, the introduction of the guide agent TPA + The desilication process is more controllable and selective, and the pore size, the number and the pore size distribution of the mesopores formed in the crystal phase are determined. The outer surface of AT-4 is provided with a layer of transparent amorphous SiO compared with AT-3 2 While the internal structure is not affected, which is consistent with the characterization results of the X-ray diffraction pattern and the nitrogen adsorption-desorption isotherm.
FIG. 4 is a sample of HZSM-5, prepared Gao Jiekong degrees HZSM-5@SiO of example 1 2 The ammonia gas of composite molecular sieves (AT-4), AT-1, AT-2 and AT-3 of comparative examples 1-3 was desorbed by temperature programmed, and the acid amount distribution is shown in Table 2. As can be seen in FIG. 4, all samples exhibited two desorption peaks at 190℃and 430℃which are weak and strong acids, respectively, of the HZSM-5 molecular sieve. The different treatment methods have obvious influence on the weak acid strength of the molecular sieve, and the position of the desorption peak is according to AT-1>AT-3>HASM-5≈AT-2>AT-4 was successively lower, indicating inert SiO 2 Can effectively reduce the acid strength of the molecular sieve surface. As can be seen from Table 2, the total acid content of the alkali treated sample increased significantly, which is probably due to the molecular sieve desilication exposing part of the framework aluminum, the acid content was according to AT-1>AT-3>HZSM-5 and AT-2 and AT-4 decrease in sequence, which further complements the demonstration of amorphous SiO deposition on the AT-3 surface 2 (i.e., AT-4) can deactivate mesoporous and external acid sites.
TABLE 2 acid quantity distribution of HZSM-5 and AT-1 to AT-4
Figure BDA0002593864860000101
FIG. 5 is a sample of HZSM-5, prepared Gao Jiekong degrees HZSM-5@SiO of example 1 2 Composite molecular sieves (AT-4) and AT-1, AT-2 and AT-3 deactivated catalysts of comparative examples 1-3As can be seen from fig. 5, the carbon deposition amount and the carbon deposition rate of AT-4 are significantly reduced compared with AT-1, indicating that the stability and the service life of the catalyst are greatly improved.
Table 3 shows the starting material HZSM-5 of example 1, prepared Gao Jiekong degrees HZSM-5@SiO 2 Performance evaluation table of methanol aromatization with composite molecular sieves (AT-4) AT-1, AT-2 and AT-3 of comparative examples 1-3 as catalysts. As can be seen from Table 3, the selectivity for light aromatic hydrocarbons (benzene, toluene and xylene) is in accordance with AT-4>AT-3>AT-2≈AT-1>HZSM-5 is reduced in sequence, meanwhile, the light aromatic hydrocarbon of AT-4 accounts for 66.73% AT the highest, and the heavy aromatic hydrocarbon accounts for 21.41% AT the lowest, which shows that the highly-dispersed and strongly-communicated micro-mesoporous structure introduced in the AT-4 effectively improves the diffusion property of the pore canal, so that the generated light aromatic hydrocarbon product can be desorbed rapidly, accumulation in micropores is avoided, and further isomerization to generate coke due to the blocking of the pore canal by the heavy aromatic hydrocarbon is reduced. Simultaneously depositing amorphous inert SiO on the surface of the catalyst 2 On the one hand, the acid sites on the outer surface of the catalyst are covered under the condition that the internal pore canal of the catalyst is not influenced, and the accumulation of coke on the active sites can be slowed down; on one hand, the effective pore diameter of the zeolite is regulated, and the shape-selective separation capability of the catalyst is improved.
TABLE 3 evaluation of catalytic Performance of HZSM-5 and AT-1 to AT-4 when used as catalysts
Figure BDA0002593864860000111
In summary, gao Jiekong degree HZSM-5@SiO prepared in example 1 2 The core of the composite molecular sieve has a large number of highly-dispersed and strongly-communicated micro-mesoporous structures, so that the diffusion and the reaction activity of molecules are greatly promoted; at the same time inert SiO 2 The thin shell layer can well inhibit the secondary isomerization reaction of aromatic hydrocarbon, can effectively modulate the pore size of HZSM-5 zeolite, and greatly improves the shape selective catalytic capability of zeolite. The method can accurately control the specific surface area and the pore size of the mesoporous of the catalyst core by modulating the type and the dosage of the guide hole agent PDAs; and the existence of the guide hole agent PDAs can effectively prevent the desilication processDisorder, the inherent property of the catalyst core is maintained to the maximum extent, and the catalyst has micro-mesoporous structures and connectivity of different layers. Then, by depositing modifiers of different sizes at the orifice of the Gao Jiekong degree HZSM-5 core, fine tuning thereof can greatly improve the shape selectivity of the reactants and products. Compared with the conventional microporous HZSM-5 zeolite, the preparation method of the invention prepares Gao Jiekong degrees HZSM-5@SiO 2 The composite molecular sieve has good catalytic performance and carbon deposition resistance in the reactions of isomerization, alkylation and the like.
Example 2
Gao Jiekong degree HZSM-5@SiO of this example 2 The preparation method of the composite molecular sieve comprises the following steps:
s1, mixing and stirring 100mL of mixed solution of alkali metal solution and guide hole agent PDAs and 2g of HZSM-5 to obtain slurry;
the alkali metal hydroxide solution is sodium hydroxide solution with the concentration of 1mol/L; the guide hole agent PDAs is anionic surfactant DS - ；
The anionic surfactant DS - Molecular formula CH 3 (CH 2 ) 11 OSO 3 - The structural formula is as follows:
Figure BDA0002593864860000121
wherein Na is + And DS - The molar ratio of (2) is 1:2;
s2, stirring the slurry obtained in the step S1 for 6 hours at the temperature of 50 ℃ to form gel mixed solution, cooling to room temperature, filtering, washing with distilled water for multiple times to neutrality and drying to obtain a Gao Jiekong-DEG NaZSM-5 molecular sieve;
s3, mixing the Gao Jiekong-degree NaZSM-5 molecular sieve obtained in S2 with NH with the concentration of 1mol/L 4 NO 3 Mixing the solutions, performing ion exchange at 80 ℃, drying, and roasting at 650 ℃ for 2 hours to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystals; the Gao Jiekong-DEG NaZSM-5 molecular sieve and NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL;
s4, adding a dispersing agent (n-hexane) and a silicon source (Si (OCH) into the Gao Jiekong-DEG HZSM-5 molecular sieve seed crystal obtained in S3 3 ) 4 ) Then carrying out hydrothermal crystallization for 38 hours at the temperature of 100 ℃, washing with distilled water for multiple times to neutrality, drying, and roasting for 2 hours at the temperature of 650 ℃ to obtain Gao Jiekong-DEG HZSM-5@SiO 2 A composite molecular sieve; the mass ratio of the Gao Jiekong-degree HZSM-5 molecular sieve seed crystal, the dispersing agent and the silicon source is 1:12:3, a step of; the Gao Jiekong-degree HZSM-5@SiO 2 The specific surface area of the composite molecular sieve is 330m 2 Per g, mesoporous volume of 0.25cm 3 The pore diameter of the most probable pore is 2nm.
Example 3
Gao Jiekong degree HZSM-5@SiO of this example 2 The preparation method of the composite molecular sieve comprises the following steps:
s1, mixing 100mL of mixed solution of alkali metal solution and guide hole agent PDAs and 5g of HZSM-5, and stirring to obtain slurry;
the alkali metal hydroxide solution is sodium hydroxide solution with the concentration of 0.1 mol/L; the guide hole agent PDAs is nonionic surfactant EDA;
the molecular formula of the nonionic surfactant EDA is C 2 H 4 (NH 2 ) 2 The structural formula is as follows:
Figure BDA0002593864860000131
wherein Na is + And EDA in a molar ratio of 2:3;
s2, stirring the slurry obtained in the step S1 for 2 hours at the temperature of 90 ℃ to form gel mixed solution, cooling to room temperature, filtering, washing with distilled water for many times to neutrality and drying to obtain a Gao Jiekong-DEG NaZSM-5 molecular sieve;
s3, mixing the Gao Jiekong-degree NaZSM-5 molecular sieve obtained in S2 with NH with the concentration of 0.5mol/L 4 NO 3 Mixing the solutions, performing ion exchange at 80 ℃, drying, and roasting at 650 ℃ for 2 hours to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystals; the Gao Jiekong-DEG NaZSM-5 molecular sieve and NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL;
s4, adding a dispersing agent (n-heptane) and a silicon source (SiCl) into the Gao Jiekong-DEG HZSM-5 molecular sieve seed crystal obtained in the step S3 4 ) Then carrying out hydrothermal crystallization for 14h at 200 ℃, washing with distilled water for many times to neutrality, drying, and roasting for 2h at 650 ℃ to obtain Gao Jiekong-DEG HZSM-5@SiO 2 A composite molecular sieve; the mass ratio of the Gao Jiekong-degree HZSM-5 molecular sieve seed crystal to the dispersing agent to the silicon source is 2:14:5, a step of; the Gao Jiekong-degree HZSM-5@SiO 2 The specific surface area of the composite molecular sieve is 380m 2 Per g, mesoporous volume of 0.35cm 3 The most probable pore size is 22nm.
Example 4
Gao Jiekong degree HZSM-5@SiO of this example 2 The preparation method of the composite molecular sieve comprises the following steps:
s1, mixing 100mL of mixed solution of alkali metal solution and guide hole agent PDAs and 5g of HZSM-5, and stirring to obtain slurry;
the alkali metal hydroxide solution is potassium hydroxide solution with the concentration of 1mol/L; the guide hole agent PDAs is nonionic surfactant DAH;
the molecular formula of the nonionic surfactant DAH is H 2 N(CH 2 ) 6 NH 2 The structural formula is as follows:
Figure BDA0002593864860000141
wherein K is + And DS - The molar ratio of (2) is 3:4;
s2, stirring the slurry obtained in the step S1 for 6 hours at the temperature of 50 ℃ to form gel mixed solution, cooling to room temperature, filtering, washing with distilled water for many times to neutrality and drying to obtain a Gao Jiekong-DEG KZSM-5 molecular sieve;
s3, mixing Gao Jiekong-degree KZSM-5 molecular sieve obtained in S2 with NH with concentration of 1mol/L 4 NO 3 Mixing the solutions, performing ion exchange at 80deg.C, drying, and dryingRoasting for 3 hours at 550 ℃ to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystals; gao Jiekong degree KZSM-5 molecular sieve and NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL;
s4, adding a dispersing agent (n-hexane) and a silicon source (SiCl) into the Gao Jiekong-DEG HZSM-5 molecular sieve seed crystal obtained in the step S3 4 ) Then carrying out hydrothermal crystallization for 38 hours at 110 ℃, washing with distilled water for multiple times to neutrality, drying, and roasting for 2.5 hours at 600 ℃ to obtain Gao Jiekong-DEG HZSM-5@SiO 2 A composite molecular sieve; the mass ratio of the Gao Jiekong-degree HZSM-5 molecular sieve seed crystal to the dispersing agent to the silicon source is 2:15:10; the Gao Jiekong-degree HZSM-5@SiO 2 The specific surface area of the composite molecular sieve is 360m 2 Per g, mesoporous volume of 0.30cm 3 The most probable pore size is 25nm.
Example 5
Gao Jiekong degree HZSM-5@SiO of this example 2 The preparation method of the composite molecular sieve comprises the following steps:
s1, mixing and stirring 100mL of mixed solution of alkali metal solution and guide hole agent PDAs and 2g of HZSM-5 to obtain slurry;
the alkali metal hydroxide solution is potassium hydroxide solution with the concentration of 1mol/L; the guide hole agent PDAs is nonionic surfactant TAEA;
the nonionic surfactant TAEA has a molecular formula of N (CH) 2 CH 2 NH 2 ) 3 The structural formula is as follows:
Figure BDA0002593864860000151
wherein K is + And TAEA in a molar ratio of 3:5;
s2, stirring the slurry obtained in the step S1 for 3 hours at the temperature of 60 ℃ to form gel mixed solution, cooling to room temperature, filtering, washing with distilled water for multiple times to neutrality and drying to obtain a Gao Jiekong-DEG KZSM-5 molecular sieve;
s3, mixing Gao Jiekong-degree KZSM-5 molecular sieve obtained in S2 with NH with the concentration of 0.5mol/L 4 NO 3 Mixing the solutions, and performing ion at 80deg.CAfter exchange, drying and roasting for 3 hours at 550 ℃ to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystals; gao Jiekong degree KZSM-5 molecular sieve and NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL;
s4, adding a dispersing agent (n-heptane) and a silicon source (Si (OCH) into the Gao Jiekong-DEG HZSM-5 molecular sieve seed crystal obtained in S3 3 ) 4 ) Then carrying out hydrothermal crystallization for 20 hours at 150 ℃, washing with distilled water for many times to neutrality, drying, and roasting for 3 hours at 550 ℃ to obtain Gao Jiekong-DEG HZSM-5@SiO 2 A composite molecular sieve; the mass ratio of the Gao Jiekong-degree HZSM-5 molecular sieve seed crystal to the dispersing agent to the silicon source is 3:18:7, preparing a base material; the Gao Jiekong-degree HZSM-5@SiO 2 The specific surface area of the composite molecular sieve is 400m 2 Per g, mesoporous volume of 0.42cm 3 The most probable pore size is 8nm.
Example 6
Gao Jiekong degree HZSM-5@SiO of this example 2 The preparation method of the composite molecular sieve comprises the following steps:
s1, mixing 100mL of mixed solution of alkali metal solution and guide hole agent PDAs and 5g of HZSM-5, and stirring to obtain slurry;
the alkali metal hydroxide solution is potassium hydroxide solution with the concentration of 1mol/L; the guide hole agent PDAs is nonionic surfactant DEA;
the molecular formula of the nonionic surfactant DEA is HN (CH) 2 CH 3 ) 2 The structural formula is as follows:
Figure BDA0002593864860000161
wherein K is + And DEA in a molar ratio of 4:5;
s2, stirring the slurry obtained in the step S1 for 2 hours at the temperature of 90 ℃ to form gel mixed solution, cooling to room temperature, filtering, washing with distilled water for many times to neutrality and drying to obtain a Gao Jiekong-DEG NaZSM-5 molecular sieve;
s3, mixing the Gao Jiekong-degree NaZSM-5 molecular sieve obtained in S2 with NH with the concentration of 0.5mol/L 4 NO 3 Mixing the solutions inIon exchange is carried out at 80 ℃, and then drying and roasting are carried out for 3 hours at 550 ℃ to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystal; the Gao Jiekong-DEG NaZSM-5 molecular sieve and NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL;
s4, adding dispersant (n-heptane) and silicon source (Si (OC) 2 H 5 ) 4 ) Then carrying out hydrothermal crystallization for 16h at 120 ℃, washing with distilled water for many times to neutrality, drying, and roasting for 3h at 550 ℃ to obtain Gao Jiekong-DEG HZSM-5@SiO 2 A composite molecular sieve; the mass ratio of the Gao Jiekong-degree HZSM-5 molecular sieve seed crystal to the dispersing agent to the silicon source is 2:18:15; the Gao Jiekong-degree HZSM-5@SiO 2 The specific surface area of the composite molecular sieve is 400m 2 Per g, mesoporous volume of 0.28cm 3 The most probable pore size is 12nm.
Example 7
Gao Jiekong degree HZSM-5@SiO of this example 2 The preparation method of the composite molecular sieve comprises the following steps:
s1, mixing 100mL of mixed solution of alkali metal solution and guide hole agent PDAs and 5g of HZSM-5, and stirring to obtain slurry;
the alkali metal hydroxide solution is sodium hydroxide solution with the concentration of 1mol/L; the guide hole agent PDAs is cationic surfactant PTA + ；
The cationic surfactant PTA + Molecular formula (CH) 3 ) 3 N + C 3 H 7 The structural formula is as follows:
Figure BDA0002593864860000171
wherein Na is + And PTA (pure terephthalic acid) + The molar ratio of (2) to (5);
s2, stirring the slurry obtained in the step S1 for 5 hours at the temperature of 80 ℃ to form gel mixed solution, cooling to room temperature, filtering, washing with distilled water for multiple times to neutrality and drying to obtain a Gao Jiekong-DEG NaZSM-5 molecular sieve;
s3, willGao Jiekong degree NaZSM-5 molecular sieve obtained in S2 and NH concentration of 0.5mol/L 4 NO 3 Mixing the solutions, performing ion exchange at 80 ℃, drying, and roasting at 550 ℃ for 3 hours to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystals; the Gao Jiekong-DEG NaZSM-5 molecular sieve and NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL;
s4, adding a dispersing agent (n-heptane) and a silicon source (SiCl) into the Gao Jiekong-DEG HZSM-5 molecular sieve seed crystal obtained in the step S3 4 ) Then carrying out hydrothermal crystallization for 30 hours at 170 ℃, washing with distilled water for many times to neutrality, drying, and roasting for 2.4 hours at 580 ℃ to obtain Gao Jiekong-DEG HZSM-5@SiO 2 A composite molecular sieve; the mass ratio of the Gao Jiekong-degree HZSM-5 molecular sieve seed crystal to the dispersing agent to the silicon source is 4:25:18; the Gao Jiekong-degree HZSM-5@SiO 2 The specific surface area of the composite molecular sieve is 410m 2 Per g, mesoporous volume of 0.33cm 3 The pore diameter of the most probable pore is 18nm.
Example 8
Gao Jiekong degree HZSM-5@SiO of this example 2 The preparation method of the composite molecular sieve comprises the following steps:
s1, mixing and stirring 100mL of mixed solution of alkali metal solution and guide hole agent PDAs and 2g of HZSM-5 to obtain slurry;
the alkali metal hydroxide solution is sodium hydroxide solution with the concentration of 1mol/L; the guide hole agent PDAs is cationic surfactant CTA + ；
The cationic surfactant CTA + Molecular formula (CH) 3 ) 3 N + C 12 H 25 The structural formula is as follows:
Figure BDA0002593864860000181
wherein Na is + And CTA + The molar ratio of (2) is 1:1;
s2, stirring the slurry obtained in the S1 for 2-6 h (4) at the temperature of 50-90 ℃ (80) to form gel mixed solution, cooling to room temperature, filtering, washing with distilled water for multiple times to neutrality and drying to obtain a Gao Jiekong-DEG NaZSM-5 molecular sieve;
s3, mixing the Gao Jiekong-degree NaZSM-5 molecular sieve obtained in S2 with NH with the concentration of 0.5mol/L 4 NO 3 Mixing the solutions, performing ion exchange at 80 ℃, drying, and roasting at 580 ℃ for 2.5 hours to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystals; the Gao Jiekong-DEG NaZSM-5 molecular sieve and NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL;
s4, adding a dispersing agent (n-hexane) and a silicon source (Si (OCH) into the Gao Jiekong-DEG HZSM-5 molecular sieve seed crystal obtained in S3 3 ) 4 ) Then carrying out hydrothermal crystallization for 18h at 130 ℃, washing with distilled water for many times to neutrality, drying, and roasting for 2.2h at 570 ℃ to obtain Gao Jiekong-DEG HZSM-5@SiO 2 A composite molecular sieve; the mass ratio of the Gao Jiekong-degree HZSM-5 molecular sieve seed crystal to the dispersing agent to the silicon source is 4:15:37, respectively; the Gao Jiekong-degree HZSM-5@SiO 2 The specific surface area of the composite molecular sieve is 340m 2 Per g, mesoporous volume of 0.28cm 3 The most probable pore size is 8nm.
Example 9
Gao Jiekong degree HZSM-5@SiO of this example 2 The preparation method of the composite molecular sieve comprises the following steps:
s1, mixing and stirring 100mL of mixed solution of alkali metal solution and guide hole agent PDAs and 2g of HZSM-5 to obtain slurry;
the alkali metal hydroxide solution is potassium hydroxide solution with the concentration of 1mol/L; the guide hole agent PDAs is cationic surfactant DSA + ；
The cationic surfactant DSA + Molecular formula (C) 18 H 37 ) 2 N + (CH 3 ) 3 The structural formula is as follows:
Figure BDA0002593864860000191
wherein K is + And DSA + The molar ratio of (2) is 1:5; />
S2, stirring the slurry obtained in the step S1 for 4 hours at the temperature of 80 ℃ to form gel mixed solution, cooling to room temperature, filtering, washing with distilled water for multiple times to neutrality and drying to obtain a Gao Jiekong-DEG KaZSM-5 molecular sieve;
s3, mixing Gao Jiekong-degree KZSM-5 molecular sieve obtained in S2 with NH with concentration of 1mol/L 4 NO 3 Mixing the solutions, performing ion exchange at 80 ℃, drying, and roasting at 550 ℃ for 3 hours to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystals; gao Jiekong degree KZSM-5 molecular sieve and NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL;
s4, adding dispersant (n-hexane) and silicon source (Si (OC) 2 H 5 ) 4 ) Then carrying out hydrothermal crystallization for 30 hours at 170 ℃, washing with distilled water for many times to neutrality, drying, and roasting for 2.5 hours at 560 ℃ to obtain Gao Jiekong-DEG HZSM-5@SiO 2 A composite molecular sieve; the mass ratio of the Gao Jiekong-degree HZSM-5 molecular sieve seed crystal, the dispersing agent and the silicon source is 5:17:38, a step of carrying out the process; the Gao Jiekong-degree HZSM-5@SiO 2 The specific surface area of the composite molecular sieve is 340m 2 Per g, mesoporous volume of 0.33cm 3 The pore diameter of the most probable pore is 20nm.
Example 10
Gao Jiekong degree HZSM-5@SiO of this example 2 The preparation method of the composite molecular sieve comprises the following steps:
s1, mixing 100mL of mixed solution of alkali metal solution and guide hole agent PDAs and 5g of HZSM-5, and stirring to obtain slurry;
the alkali metal hydroxide solution is potassium hydroxide solution with the concentration of 1mol/L; the guide pore agent PDAs is a cationic surfactant HM 2+ ；
The cationic surfactant HM 2+ Molecular formula (CH) 3 ) 3 N + C 6 H 12 N + (CH 3 ) 3 The structural formula is as follows:
Figure BDA0002593864860000201
wherein K is + Sum HM 2+ The molar ratio of (2) is 5:7;
s2, stirring the slurry obtained in the step S1 for 3 hours at the temperature of 60 ℃ to form gel mixed solution, cooling to room temperature, filtering, washing with distilled water for multiple times to neutrality and drying to obtain a Gao Jiekong-DEG KZSM-5 molecular sieve;
s3, mixing Gao Jiekong-degree KZSM-5 molecular sieve obtained in S2 with NH with concentration of 1mol/L 4 NO 3 Mixing the solutions, performing ion exchange at 80 ℃, drying, and roasting at 650 ℃ for 2 hours to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystals; gao Jiekong degree KZSM-5 molecular sieve and NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL;
s4, adding a dispersing agent (n-heptane) and a silicon source (SiCl) into the Gao Jiekong-DEG HZSM-5 molecular sieve seed crystal obtained in the step S3 4 ) Then carrying out hydrothermal crystallization for 22 hours at 150 ℃, washing with distilled water for many times to neutrality, drying, and roasting for 3 hours at 550 ℃ to obtain Gao Jiekong-DEG HZSM-5@SiO 2 A composite molecular sieve; the mass ratio of the Gao Jiekong-degree HZSM-5 molecular sieve seed crystal, the dispersing agent and the silicon source is 5:28:32; the Gao Jiekong-degree HZSM-5@SiO 2 The specific surface area of the composite molecular sieve is 420m 2 Per g, mesoporous volume of 0.45cm 3 The pore diameter of the most probable pore is 30nm.
Example 11
Gao Jiekong degree HZSM-5@SiO of this example 2 The preparation method of the composite molecular sieve comprises the following steps:
s1, mixing 100mL of mixed solution of alkali metal solution and guide hole agent PDAs and 5g of HZSM-5, and stirring to obtain slurry;
the alkali metal hydroxide solution is sodium hydroxide solution with the concentration of 1mol/L; the guide hole agent PDAs is cationic surfactant HDP + ；
The cationic surfactant HDP + Molecular formula C 16 H 33 N + C 5 H 5 The structural formula is as follows:
Figure BDA0002593864860000211
wherein Na is + And HDP + The molar ratio of (2) is 3:8;
s2, stirring the slurry obtained in the step S1 for 5 hours at the temperature of 80 ℃ to form gel mixed solution, cooling to room temperature, filtering, washing with distilled water for multiple times to neutrality and drying to obtain a Gao Jiekong-DEG NaZSM-5 molecular sieve;
s3, mixing the Gao Jiekong-degree NaZSM-5 molecular sieve obtained in S2 with NH with the concentration of 1mol/L 4 NO 3 Mixing the solutions, performing ion exchange at 80 ℃, drying, and roasting at 550 ℃ for 3 hours to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystals; the Gao Jiekong-DEG NaZSM-5 molecular sieve and NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL;
s4, adding a dispersing agent (n-hexane) and a silicon source (SiCl) into the Gao Jiekong-DEG HZSM-5 molecular sieve seed crystal obtained in the step S3 4 ) Then carrying out hydrothermal crystallization for 14h at 190 ℃, washing with distilled water for many times to neutrality, drying, and roasting for 3h at 550 ℃ to obtain Gao Jiekong-DEG HZSM-5@SiO 2 A composite molecular sieve; the mass ratio of the Gao Jiekong-degree HZSM-5 molecular sieve seed crystal, the dispersing agent and the silicon source is 6:17:33; the Gao Jiekong-degree HZSM-5@SiO 2 The specific surface area of the composite molecular sieve is 370m 2 Per g, mesoporous volume of 0.32cm 3 The pore diameter of the most probable pore is 18nm.
Example 12
Gao Jiekong degree HZSM-5@SiO of this example 2 The preparation method of the composite molecular sieve comprises the following steps:
s1, mixing 100mL of mixed solution of alkali metal solution and guide hole agent PDAs and 5g of HZSM-5, and stirring to obtain slurry;
the alkali metal hydroxide solution is sodium hydroxide solution with concentration of 0.1mol/LA liquid; the guide hole agent PDAs is cationic surfactant BA + ；
The cationic surfactant BA + Molecular formula C 6 H 5 CH 2 N + (CH 3 ) 2 R，R＝C 8 H 17 to C 16 H 33 The structural formula is as follows:
Figure BDA0002593864860000221
wherein Na is + And DS - The molar ratio of (2) is 4:5;
s2, stirring the slurry obtained in the step S1 for 5 hours at the temperature of 80 ℃ to form gel mixed solution, cooling to room temperature, filtering, washing with distilled water for multiple times to neutrality and drying to obtain a Gao Jiekong-DEG NaZSM-5 molecular sieve;
s3, mixing the Gao Jiekong-degree NaZSM-5 molecular sieve obtained in S2 with NH with the concentration of 1mol/L 4 NO 3 Mixing the solutions, performing ion exchange at 80 ℃, drying, and roasting at 550 ℃ for 3 hours to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystals; the Gao Jiekong-DEG NaZSM-5 molecular sieve and NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL;
s4, adding a dispersing agent (n-heptane) and a silicon source (Si (OCH) into the Gao Jiekong-DEG HZSM-5 molecular sieve seed crystal obtained in S3 3 ) 4 ) Then carrying out hydrothermal crystallization for 38 hours at the temperature of 100 ℃, washing with distilled water for multiple times to neutrality, drying, and roasting for 3 hours at the temperature of 550 ℃ to obtain Gao Jiekong-DEG HZSM-5@SiO 2 A composite molecular sieve; the mass ratio of the Gao Jiekong-degree HZSM-5 molecular sieve seed crystal, the dispersing agent and the silicon source is 7:21:35; the Gao Jiekong-degree HZSM-5@SiO 2 The specific surface area of the composite molecular sieve is 400m 2 Per g, mesoporous volume of 0.25cm 3 The pore diameter of the most probable pore is 20nm.
The above description is only of the preferred embodiments of the present invention, and is not intended to limit the present invention. Any simple modification, variation and equivalent variation of the above embodiments according to the technical substance of the invention still fall within the scope of the technical solution of the invention.

Claims (5)

1. High mesoporous HZSM-5@SiO 2 The preparation method of the composite molecular sieve is characterized by comprising the following steps:
s1, mixing and stirring mixed solution of alkali metal solution and guide hole agent PDAs and HZSM-5 to obtain slurry;
the mixed solution of the alkali metal solution and the guide hole agent PDAs is a mixture of alkali metal hydroxide solution and guide hole agent PDAs with the mol ratio of 1 (1-5); the concentration of the alkali metal hydroxide solution is 0.1 mol/L-1 mol/L;
the alkali metal hydroxide solution in S1 is sodium hydroxide solution or potassium hydroxide solution; the guide hole agent PDAs are anionic surfactants, nonionic surfactants or cationic surfactants;
the anionic surfactant is DS - The method comprises the steps of carrying out a first treatment on the surface of the The nonionic surfactant is EDA, DAH, TAEA or DEA; the cationic surfactant is PTA + 、TPA + 、CTA + 、DSA + 、HM 2+ 、HDP + Or BA (A) + ；
S2, stirring the slurry obtained in the step S1 for 2-6 hours at the temperature of 50-90 ℃ to form gel mixed solution, cooling to room temperature, and filtering, washing and drying to obtain Gao Jiekong-DEG XZSM-5 molecular sieve; x in the Gao Jiekong-degree XZSM-5 molecular sieve represents alkali metal;
s3, mixing Gao Jiekong-degree XZSM-5 molecular sieve obtained in S2 with NH with concentration of 0.5 mol/L-1 mol/L 4 NO 3 Mixing the solutions, performing ion exchange at 80 ℃, drying, and roasting at 550-650 ℃ for 2-3 hours to obtain Gao Jiekong-DEG HZSM-5 molecular sieve seed crystals;
s4, adding a dispersing agent and a silicon source into the Gao Jiekong-DEG H ZSM-5 molecular sieve seed crystal obtained in the S3, performing hydrothermal crystallization for 12-38 hours at 100-200 ℃, washing and drying, and then obtaining the catalystRoasting for 2-3 hours at 550-650 ℃ to obtain Gao Jiekong-DEG HZSM-5@SiO 2 A composite molecular sieve; the Gao Jiekong-degree HZSM-5@SiO 2 The composite molecular sieve is used for selectively catalyzing the aromatization of the methanol into light aromatic hydrocarbon;
the dispersant in S4 is n-hexane or n-heptane; the silicon source is Si (OCH) 3 ) 4 、Si(OC 2 H 5 ) 4 Or SiCl 4 ；
Gao Jiekong degree HZSM-5@SiO as described in S4 2 The specific surface area of the composite molecular sieve is 276m 2 /g～420m 2 Per g, mesoporous volume of 0.23cm 3 /g～0.45cm 3 The most probable pore diameter is 2 nm-30 nm.
2. A high mesoporous HZSM-5@SiO according to claim 1 2 The preparation method of the composite molecular sieve is characterized in that the dosage ratio of the mixed solution of the alkali metal solution and the guide pore agent PDAs in the slurry in S1 to HZSM-5 is (20-50) mL:1g.
3. A high mesoporous HZSM-5@SiO according to claim 1 2 The preparation method of the composite molecular sieve is characterized in that the washing methods in S2 and S4 are all to wash with distilled water for many times to neutrality.
4. A high mesoporous HZSM-5@SiO according to claim 1 2 The preparation method of the composite molecular sieve is characterized in that the Gao Jiekong-degree XZSM-5 molecular sieve in S3 and NH 4 NO 3 The dosage ratio of the solution is 1g to 40mL.
5. A high mesoporous HZSM-5@SiO according to claim 1 2 The preparation method of the composite molecular sieve is characterized in that the mass ratio of the Gao Jiekong-degree HZSM-5 molecular sieve seed crystal, the dispersing agent and the silicon source in S4 is (1-7): (12-28): (3-38).
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