A zsm-12-alpo4-5 composite structure zeolite and a method for synthesizing the same

Abstract

The application discloses a ZSM-12 zeolite-AlPO4-5 zeolite composite structure zeolite and a synthesis method thereof. The composite structure zeolite is a core phase of ZSM-12 zeolite and a shell phase of AlPO4-5 zeolite, and the synthesis method comprises the following steps: (1) uniformly mixing ZSM-12 zeolite, an aluminum source, ammonium hydroxide, alcohol and water; then sequentially performing dynamic treatment and static treatment; and performing separation and drying to obtain an aluminum oxide-ZSM-12 zeolite composite, wherein the aluminum source is organic aluminum alcohol; (2) mixing the aluminum oxide-ZSM-12 zeolite composite obtained in the step (1), water, nano iron oxide particles and sugar, evaporating water, then performing heating treatment in an inert atmosphere, then performing acid treatment, and then performing separation and drying to obtain a carbon-aluminum oxide-zeolite composite; and (3) mixing water, the carbon-aluminum oxide-zeolite composite obtained in the step (2), phosphoric acid and a template agent, performing crystallization reaction, and then performing separation, drying and calcination to obtain the composite zeolite. The composite structure zeolite has a stable core-shell structure and can be used as a catalyst or a catalyst carrier.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of a composite structure zeolite, and belongs to the field of inorganic porous material synthesis, in particular to a ZSM-12 zeolite-AlPO4-5 zeolite core-shell type composite structure zeolite and a synthesis method thereof. BACKGROUND

[0002] Composite zeolite is a kind of porous material with special structure. This material combines zeolite molecular sieves with different pore structures and acidities together by using special synthesis technology, and exhibits synergistic catalytic performance which single zeolite does not have. This kind of material avoids the shortcomings of single zeolite, and can effectively solve the mass transfer problem in the reaction process, and has wide application prospects in macromolecular catalysis, catalyst carrier and heavy oil cracking, etc.

[0003] The existing core-shell structure molecular sieve is mostly prepared by embedding method, that is, the core phase molecular sieve is directly added into the gel of the shell layer molecular sieve, and then hydrothermally crystallized to obtain the product. CN1524617A discloses a synthesis method of ZSM-5 / AlPO4-5 double structure molecular sieve, which comprises the following steps: weighing aluminum source, phosphorus source, template agent, ZSM-5 and water, mixing and stirring uniformly at 20-80°C, hydrothermally crystallizing at 110-150°C for 5-48 hours and hydrothermally crystallizing at 160-200°C for 12-120 hours in sequence, and recovering the product obtained after crystallization.

[0004] ZSM-12-AlPO4-5 core-shell structure composite zeolite is a kind of composite zeolite with special structure, in which ZSM-12 zeolite is used as the core similar to the yolk in the center of the material, and AlPO4-5 zeolite is used as the shell layer similar to the protein wrapped in the outer layer of the core. The main problem existing in the existing technology for synthesizing ZSM-12-AlPO4-5 core-shell structure composite zeolite is that, under the condition of keeping the framework structure of AlPO4-5 zeolite and ZSM-12 zeolite intact, either the core-shell structure cannot be formed, and most of the composite molecular sieve is in a eutectic state, or the formed core-shell structure is unstable, and the core zeolite and the shell layer zeolite are easily separated to form two independent states.

[0005] CN101279288B discloses a synthesis method of core-shell structure composite molecular sieve. The method mainly adopts positioning growth method to pre-fix the phosphorus aluminum or silicon phosphorus aluminum molecular sieve synthesis raw material on the surface of ZSM-5 molecular sieve, and then the initial wet gel is prepared by mixing with other synthesis shell layer molecular sieve raw materials, and then constant temperature crystallization is carried out to synthesize the core-shell structure composite molecular sieve. However, the stability of the method is insufficient, and the synthesized product often appears in a non-core-shell structure, but an independent structure. SUMMARY

[0006] In view of the deficiencies in the prior art, the present application provides a ZSM-12 zeolite-AlPO4-5 zeolite composite structure zeolite and a synthesis method thereof.The ZSM-12 zeolite-AlPO4-5 zeolite composite structure zeolite can maintain the integrity and crystallinity of the ZSM-12 zeolite-AlPO4-5 zeolite framework structure, and the core-shell combination is tight and does not separate and the structure is stable.

[0007] The first aspect of the present application provides a ZSM-12 zeolite-AlPO4-5 zeolite composite structure zeolite, wherein the ZSM-12 zeolite is a core phase, the AlPO4-5 zeolite is a shell phase, and the specific surface area of the composite structure zeolite is 450-900 m 2 / g

[0008] In the present application, the shell layer thickness of the composite structure zeolite is 20-150 nm.

[0009] The second aspect of the present application provides a synthesis method of a ZSM-12 zeolite-AlPO4-5 zeolite composite structure zeolite, comprising:

[0010] (1) uniformly mixing ZSM-12 zeolite, an aluminum source, ammonium hydroxide, an alcohol, and water, then sequentially performing dynamic treatment and static treatment, then separating and drying solid substances to obtain an aluminum oxide-ZSM-12 zeolite composite, and the aluminum source is an organic aluminum alcohol;

[0011] (2) mixing the aluminum oxide-ZSM-12 zeolite composite obtained in step (1), water, nano iron oxide particles, and a sugar, then evaporating water, then heating under an inert atmosphere, then performing acid treatment, then performing separation and drying to obtain a carbon-aluminum oxide-zeolite composite;

[0012] (3) mixing water, the carbon-aluminum oxide-ZSM-12 zeolite composite obtained in step (2), phosphoric acid, and a template, then performing a crystallization reaction, then performing separation, drying, and calcination to obtain a composite zeolite.

[0013] In the method of the present application, the particle size of the ZSM-12 zeolite in step (1) is 400-2500 nm, and is preferably 600-2000 nm.

[0014] In the method of the present application, the aluminum source in step (1) is at least one of aluminum isopropoxide, aluminum butoxide, and aluminum sec-butylate. The aluminum source decomposes amorphous aluminum oxide microparticles, which are then adsorbed on the outer surface of the core zeolite, and then form a shell layer in the form of amorphous aluminum oxide on the outer surface of the core zeolite in step (1), forming an aluminum oxide-zeolite core-shell structure.

[0015] In the method of the present application, the alcohol in step (1) is at least one of ethanol, propanol, and butanol.

[0016] In the method of the present application, the mass ratio of the zeolite, the aluminum source, the ammonium hydroxide, the alcohol, the water in step (1) is 1:0.1-1.5:0.1-1.5:40-130:15-60, preferably 1:0.05-0.1:0.2-0.5:10-50:10-50, calculated as Al2O3.

[0017] In the method of the present application, the aluminum source in step (1) is preferably added dropwise slowly, so that no large aluminum gel is formed, and a stable and uniform aluminum gel structure is formed.

[0018] In the method of the present application, the dynamic treatment in step (1) is stirring the mixed solution system, and the stirring time is 1-15 h, preferably 2-10 h. The dynamic treatment is carried out at a certain temperature, and the temperature is 20-70℃, preferably 30-60℃. During the dynamic treatment, the aluminum source is hydrolyzed into amorphous aluminum oxide; with the extension of time, an aluminum oxide gel layer is gradually formed on the outer surface of the zeolite.

[0019] In the method of the present application, the static treatment in step (1) is to let the mixed solution system be static, and the static time is 1-15 h, preferably 2-10 h. The static treatment is carried out at a certain temperature, and the temperature is 20-70℃, preferably 30-60℃. The static treatment can make the gel layer adsorbed on the outer surface of the core zeolite more stable, and the binding force with the zeolite is increased, which is beneficial to the formation of the final core-shell structure.

[0020] In the method of the present application, the separation in step (1) can be carried out by filtration, which usually includes multiple filtrations, generally 1-10 times.

[0021] In the method of the present application, the drying condition in step (1) is generally drying at 100-120℃ for 5-15 h.

[0022] In the method of the present application, the sugar in step (2) is at least one of sucrose, glucose, fructose, maltose, and lactose, preferably at least one of sucrose and glucose. The sugar is converted into carbon material by dehydration and dehydrogenation of the carbon-hydrogen compound in step (1).

[0023] In the method of the present application, the particle size of the nano iron oxide particles in step (2) is 2-15 nm, preferably 5-10 nm.

[0024] In the method of the present application, the mass ratio of the ZSM-12 zeolite and the sugar in step (2) is 1:0.8-6, preferably 1:1-5. The mass ratio of the aluminum oxide-ZSM-12 zeolite composite and water is 1:80-210, preferably 1:100-200.

[0025] In the method of the present application, the mass ratio of ZSM-12 zeolite to iron oxide in step (2) is 1:0.08-0.60, preferably 1:0.10-0.50.

[0026] In the method of the present application, the temperature for evaporating water in step (2) is 80-160℃, preferably 100-150℃; the reaction time is not limited until the water is evaporated.

[0027] In the method of the present application, the temperature for heating treatment in an inert atmosphere in step (2) is 200-400℃, preferably 300-350℃, and the treatment time is 1-12h, preferably 2-10h. The inert atmosphere can be at least one of nitrogen, argon, helium, etc., preferably nitrogen. The heating treatment can convert the saccharides into carbon materials by dehydration and dehydrogenation, and the zeolite is wrapped therein. Compared with the calcination temperature for converting the saccharides into carbon materials with stable physical and chemical properties in the conventional method, the present application uses a relatively low treatment temperature, so that the carbon materials can retain a part of the various chemical groups of the saccharides, thereby making the carbon materials have certain chemical activity, which is beneficial to participating in adsorption and chemical reaction in the subsequent synthesis reaction process, promoting the synthesis of the shell material, and improving the catalytic performance and adsorption performance of the final material.

[0028] In the method of the present application, the acid used in the acid treatment in step (2) is at least one of hydrochloric acid, nitric acid and sulfuric acid. The mass concentration of the acid is 0.5%-5.5%, preferably 1%-5%.

[0029] In the method of the present application, the mass ratio of ZSM-12 zeolite to acid solution in step (2) is 1:80-210, preferably 1:100-200.

[0030] In the method of the present application, the acid treatment in step (2) is to mix the solid material after high-temperature treatment with an acid solution, and treat at 10-40℃ for 5-35min, preferably 10-30min. The purpose of using acid treatment is to remove the iron oxide in the solid material, so as to leave mesoporous channels in the carbon material, which is beneficial to the raw materials to pass through the carbon layer to participate in chemical reaction in the subsequent reaction process.

[0031] In the method of the present application, the separation in step (2) can be carried out by filtration, which usually includes multiple filtrations, generally 1-10 times.

[0032] In the method of the present application, the drying temperature in step (2) is 100-150℃, and the drying time is 1-20h.

[0033] In the method, the feeding sequence of water, the carbon-alumina-ZSM-12 zeolite composite obtained in step (2), phosphoric acid and the template agent in step (3) is preferably as follows: the carbon-alumina-ZSM-12 zeolite composite is mixed with water uniformly, and then the phosphorus source and the template agent are added in sequence.

[0034] In the method, the template agent in step (3) is at least one of triethylamine and cyclohexylamine.

[0035] In the method, the molar ratio of the phosphorus source (calculated in terms of P), water and the template agent in step (3) is 1:400-1100:0.8-5.2, preferably 1:500-1500:1-5. Wherein M is the template agent.

[0036] In the method, the mass ratio of the phosphorus source (calculated in terms of P) to the carbon-alumina-ZSM-12 zeolite composite in step (3) is 8-21:100, preferably 10-20:100.

[0037] In the method, the crystallization reaction conditions in step (3) are as follows: the crystallization reaction temperature is 150-220℃, preferably the crystallization reaction temperature is 160-210℃; the reaction time is 15-60h, preferably the reaction time is 20-50h.

[0038] In the method, the separation in step (3) can be carried out by filtration, which usually includes multiple filtrations, generally 1-10 times.

[0039] In the method, the drying temperature in step (3) is 100-150℃, and the drying time is 1-10h.

[0040] In the method, the calcination in step (3) is high-temperature calcination treatment at 400-600℃ for 1-10h, and the calcination needs to be carried out in air or oxygen. The calcination can burn the carbon material to remove it in the form of carbon dioxide, leaving only the composite zeolite.

[0041] The composite structure zeolite of the present application is mainly used in the field of petroleum chemical industry, and can be used as a catalyst or a catalyst carrier, has excellent catalytic performance in the alkylation of naphthalene and methanol, can be used for the adsorption and separation of gas and liquid, and can even be used as a sustained-release agent carrier for loading drugs.

[0042] The third aspect of the present application provides the use of the above-mentioned composite structure zeolite in a catalyst for the alkylation of naphthalene and methanol.

[0043] In the present application, the use is that the composite structure zeolite is subjected to conventional ammonium ion exchange to obtain a hydrogen type zeolite, which is a catalyst.

[0044] Compared with the prior art, the present application has the following advantages:

[0045] The inventors have found that, when synthesizing ZSM-12 zeolite-AlPO4-5 zeolite composite zeolite with traditional hydrothermal synthesis method, ZSM-12 zeolite and AlPO4-5 zeolite often exist independently instead of stable core-shell structure, and the crystallinity of ZSM-12 zeolite is low. One of the main reasons is that, during the hydrothermal synthesis process, there is a large amount of liquid water in the synthesis system, and water will continuously impact the synthesis product under the action of heat. When the structure of the synthesis product is not stable enough, the core-shell structure of the zeolite will separate, and the crystallinity of ZSM-12 zeolite will decrease. The inventors have further found that, by first preparing an alumina-ZSM-12 zeolite composite, then preparing a carbon-alumina-ZSM-12 zeolite composite, and then controlling the materials and the feeding sequence of the materials, it can be ensured that all the materials pass through the carbon material in the carbon-alumina-ZSM-12 zeolite composite, and the ZSM-12 zeolite-AlPO4-5 zeolite composite structure zeolite obtained after crystallization has a tight core-shell structure and is not easy to separate, and the framework structure of AlPO4-5 zeolite and ZSM-12 zeolite is complete. The possible mechanism analysis is as follows: a thin layer of alumina film is first formed on the surface of ZSM-12 zeolite, and then a carbon material shell with a specific mesoporous structure is covered. The chemical activity of the carbon material is improved by retaining part of the various chemical groups of the sugar substances in the carbon material at a relatively low treatment temperature. The carbon-alumina-ZSM-12 zeolite material is a solid composite material with a size of tens or even hundreds of microns, and the alumina-ZSM-12 zeolite is wrapped by the carbon material. Since the properties of the carbon material and the core zeolite are completely different, the carbon material and the core zeolite in the carbon-zeolite composite are not in close contact, but have a space of tens to hundreds of nanometers. By controlling the raw materials and the feeding sequence, the materials pass through the carbon material to reach the core zeolite, fill the space, and crystallize with the alumina on the surface of the core zeolite as an aluminum source. Due to the limitation of the space, the formed zeolite shell can only combine with the core zeolite to form a tight core-shell structure, thereby avoiding the phenomenon of mutual separation of the shell and the core zeolite caused by the severe impact of water during the crystallization reaction. In addition, the framework structure of ZSM-12 zeolite-AlPO4-5 zeolite is complete, and the various chemical groups on the carbon material are beneficial to improve the crystallinity and catalytic performance of AlPO4-5 zeolite.

[0046] The catalyst for the alkylation of naphthalene and methanol prepared from the composite structure zeolite of the present application has high activity and selectivity, and the content of 2,6-dimethylnaphthalene in the obtained product is significantly increased. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 A scanning electron microscope photograph of sample A1 obtained in Example 1 is shown.

[0048] Figure 2 The XRD spectrum of sample A1 obtained in Example 1 is shown in Figure 1.

[0049] Figure 3 The XRD spectrum of sample DA1 obtained in Comparative Example 1 is shown in Figure 2.

[0050] Figure 4 The scanning electron microscope photograph of sample DA1 obtained in Comparative Example 1 is shown in Figure 3. DETAILED DESCRIPTION

[0051] The technical solutions and effects of the present application are further illustrated below in combination with examples, but are not limited to the following examples.

[0052] The pore structure of the composite structure zeolite of the present application is characterized by N2 adsorption-desorption, which is tested by a physical adsorption instrument of Micromeritics Corporation, USA. Before testing, the sample is treated in vacuum at 300℃ for more than 4h. The total specific surface area and other parameters are calculated according to the BET formula.

[0053] The microcrystal morphology structure of the composite structure zeolite of the present application is characterized by scanning electron microscope, which is tested by a scanning electron microscope (equipped with Oxford EDS) of Japan Electronics Corporation, JSM-6301F type, working voltage: 20kV, working distance: 15mm, resolution: 1.5nm.

[0054] The crystal phase structure and crystallinity of the composite structure zeolite of the present application are characterized by X-ray diffraction, which is tested by an X-ray diffractometer of Japan Rigaku D / max2500 type, Cu target, Kα radiation source, graphite monochromator, tube voltage 40kV, tube current 80mA, scanning range 5°-40°, step 0.1°, scanning speed 1° / min.

[0055] The thickness of the shell layer of the composite structure zeolite of the present application is characterized by high-resolution transmission electron microscope, which is tested by a high-resolution transmission electron microscope of Japan JEOL Company, instrument model JEM-2200FS field emission ultra-high-resolution transmission electron microscope, acceleration voltage 200kV, point resolution 0.19nm.

[0056] Example 1

[0057] (1) A clean beaker was taken, 55g of ZSM-12 zeolite (average particle size 1000nm), 1100g of distilled water, 1100g of ethanol, 80g of ammonium hydroxide solution (mass concentration 25%) were added and mixed uniformly; the beaker was placed in a circulating water device at 50℃; then 5.1g of isopropyl alcohol aluminum was added dropwise into the beaker; then stirring was carried out for 7h; the stirring was stopped and the sample was left to stand for 6h; then the solid material was filtered out and dried at 110℃ for 12h to obtain an aluminum oxide-zeolite composite.

[0058] (2) Mix the alumina-zeolite composite from the previous step, 5000g of distilled water, 15g of iron oxide (average particle size of 6nm), and 50g of sucrose evenly; then evaporate the water at 100℃; then treat it in nitrogen at 303℃ for 6h; then mix it with 16000g (2.2wt% hydrochloric acid) for 20min; then filter the obtained sample several times, and then place it in an oven at 110℃ for 12h to obtain the carbon-alumina-zeolite composite.

[0059] (3) Take a clean beaker, add 5.5g of carbon-alumina-zeolite composite and 280g of distilled water and mix well; then add 3g of phosphoric acid and mix well; then add 5.1g of triethylamine and mix well. Then put it into a reaction vessel and treat it at 180℃ for 30h; then filter the obtained sample several times, then place it in an oven to dry at 110℃ for 12h, and finally calcine it in air at 600℃ for 3h. The obtained sample is numbered A1.

[0060] The XRD pattern of sample A1 is shown below. Figure 2 As shown in the figure, the composite material contains two types of crystals, namely AlPO4-5 zeolite and ZSM-12 zeolite. According to Table 1, both crystals have high crystallinity and high specific surface area.

[0061] Scanning electron microscope image of sample A1 is shown below. Figure 1 ,Depend on Figure 1 It is evident that the sample has a core-shell structure. The composite material has a particle size of approximately 1250 nm and consists of irregular particles. The outer shell is rough, consisting of a coarse AlPO4-5 zeolite shell with a thickness of approximately 85 nm.

[0062] Example 2

[0063] (1) Take a clean beaker, add 50g ZSM-12 zeolite (average particle size of 1300nm), 460g distilled water, 500g ethanol, and 40g ammonium hydroxide solution (mass concentration of 25%) and mix well; place the beaker in a circulating water device at 60℃; then add 4.8g aluminum isopropoxide dropwise to the beaker; stir for 10h; stop stirring and let stand for 10h; then filter out the solid material and dry at 110℃ for 12h to obtain the alumina-zeolite composite.

[0064] (2) Mix the alumina-zeolite composite from the previous step, 5000g of distilled water, 10g of iron oxide (average particle size of 6nm), and 50g of sucrose evenly; then evaporate the water at 100℃; then treat it in nitrogen at 300℃ for 10h; then mix it with 10000g (1wt% hydrochloric acid) for 10min; then filter the obtained sample several times, and then place it in an oven at 110℃ for 12h to obtain carbon-alumina-zeolite composite.

[0065] (3) Take a clean beaker, add 9.5 g of carbon-alumina-zeolite composite and 310 g of distilled water and mix well; then add 3 g of phosphoric acid and mix well; then add 3.1 g of triethylamine and mix well. Then put it into a reaction kettle and treat at 160°C for 50 h; then filter the obtained sample multiple times, then place it in an oven at 110°C for 12 h, and finally calcine it at 600°C in air for 1 h, and the obtained sample is numbered as A2.

[0066] Sample A2 belongs to a core-shell structure and contains two crystals, AlPO4-5 zeolite and ZSM-12 zeolite, both of which have high crystallinity and high specific surface area.

[0067] Example 3

[0068] (1) Take a clean beaker, add 50 g of ZSM-12 zeolite (average particle size 1100 nm), 2400 g of distilled water, 2500 g of ethanol, and 100 g of ammonium hydroxide solution (25% mass concentration) and mix well; place the beaker in a 30°C circulating water device; then add 9.4 g of isopropyl aluminum alcohol to the beaker while stirring; then stir for 2 h; stop stirring and let it stand for 2 h; then filter out the solid material and dry it at 105°C for 12 h to obtain an alumina-zeolite composite.

[0069] (2) Mix the alumina-zeolite composite from the previous step, 10000 g of distilled water, 50 g of iron oxide (average particle size 6 nm), and 250 g of sucrose; then evaporate the water at 100°C; then treat it at 350°C for 2 h under nitrogen; then mix it with 20000 g of 5% (wt) hydrochloric acid for 30 min; then filter the obtained sample multiple times, then place it in an oven at 110°C for 12 h to obtain a carbon-alumina-zeolite composite.

[0070] (3) Take a clean beaker, add 4.75 g of carbon-alumina-zeolite composite and 550 g of distilled water and mix well; then add 3 g of phosphoric acid and mix well; then add 15 g of triethylamine and mix well. Then put it into a reaction kettle and treat at 210°C for 20 h; then filter the obtained sample multiple times, then place it in an oven at 110°C for 12 h, and finally calcine it at 600°C in air for 1 h, and the obtained sample is numbered as A3.

[0071] Sample A3 belongs to a core-shell structure and contains two crystals, AlPO4-5 zeolite and ZSM-12 zeolite, both of which have high crystallinity and high specific surface area.

[0072] Example 4

[0073] (1) Take a clean beaker, add 51.5g ZSM-12 zeolite (average particle size of 1500 nm), 1200 distilled water, 1300g ethanol, 85g ammonium hydroxide solution (mass concentration of 25%) and mix well; Put the beaker in a circulating water device at 50°C; Then add 5.1g isopropyl alcohol aluminum to the beaker at the same time; Then stir for 7h; Stop stirring and stand for 6h; Then filter out the solid material and dry at 110°C for 12h to obtain an aluminum oxide-zeolite composite.

[0074] (2) Mix the aluminum oxide-zeolite composite of the above step, 5200g distilled water, 23.5g iron oxide (average particle size of 7nm), 51g glucose, and mix well; Then evaporate the water at 100°C; Then treat at 311°C for 5.5h under nitrogen; Then mix with 15500g (2.7wt% concentration of hydrochloric acid) for 20min; Then filter the obtained sample several times, and then place it in an oven at 110°C for 12h to obtain a carbon-aluminum oxide-zeolite composite.

[0075] (3) Take a clean beaker, add 5.5g carbon-aluminum oxide-zeolite composite and 280g distilled water and mix well; Then add 3.9g phosphoric acid and mix well; Then add 5.4g triethylamine and mix well. Then put it into a reaction kettle and treat at 175°C for 30h; Then filter the obtained sample several times, and then place it in an oven at 110°C for 12h, and finally calcine the obtained sample at 550°C in air for 5h, and the sample is numbered as A4.

[0076] Sample A4 belongs to a core-shell structure and contains two crystals, AlPO4-5 zeolite and ZSM-12 zeolite, both of which have high crystallinity and high specific surface area.

[0077] Example 5

[0078] (1) Take a clean beaker, add 51.5g ZSM-12 zeolite (average particle size of 1500 nm), 1200 distilled water, 1300g ethanol, 85g ammonium hydroxide solution (mass concentration of 25%) and mix well; Put the beaker in a circulating water device at 50°C; Then add 5.1g isopropyl alcohol aluminum to the beaker at the same time; Then stir for 7h; Stop stirring and stand for 6h; Then filter out the solid material and dry at 110°C for 12h to obtain an aluminum oxide-zeolite composite.

[0079] (2) Take a clean beaker, add 5.6g of the alumina-zeolite composite, 265g of distilled water, mix well; then add 3.3g of phosphoric acid, mix well; then add 3.9g of triethylamine, mix well. Then put it into a reaction kettle and treat at 180°C for 30h; then filter the obtained sample several times, and then put it into an oven at 110°C for 12h, and finally calcine at 600°C in air for 3h, and the obtained sample is numbered as A5.

[0080] (3) Take a clean beaker, add 5.6g of the alumina-zeolite composite, 265g of distilled water, mix well; then add 3.3g of phosphoric acid, mix well; then add 3.9g of triethylamine, mix well. Then put it into a reaction kettle and treat at 180°C for 30h; then filter the obtained sample several times, and then put it into an oven at 110°C for 12h, and finally calcine at 600°C in air for 3h, and the obtained sample is numbered as A5.

[0081] Sample A5 belongs to a core-shell structure, and contains two crystals, namely AlPO4-5 zeolite and ZSM-12 zeolite, both of which have high crystallinity and high specific surface area.

[0082] Comparative Example 1

[0083] Compared with Example 1, the only difference is that the carbon-alumina-zeolite material is not prepared.

[0084] (1) Take a clean beaker, add 55g of ZSM-12 zeolite (average particle size 1000nm), 1100g of distilled water, 1100g of ethanol, 80g of ammonium hydroxide solution (mass concentration 25%), mix well; put the beaker in a circulating water device at 50°C; then add 5.1g of isopropyl alcohol aluminum to the beaker at the same time; then stir for 7h; stop stirring and stand for 6h; then filter out the solid material and dry at 110°C for 12h to obtain an alumina-zeolite composite.

[0085] (2) Take a clean beaker, add 5.5g of the alumina-zeolite composite and 280g of distilled water, mix well; then add 3g of phosphoric acid, mix well; then add 5.1g of triethylamine, mix well. Then put it into a reaction kettle and treat at 180°C for 30h; then filter the obtained sample several times, and then put it into an oven at 110°C for 12h, and finally calcine at 600°C in air for 3h, and the obtained sample is numbered as DA1.

[0086] The scanning electron microscope photograph of sample DA1 is shown in Figure 4 , and Figure 4It can be seen that the sample contains two kinds of zeolites, wherein the larger crystal particles are AlPO4-5 zeolites with a size of about 950 nm, and the crystal edges and corners are relatively clear; the smaller crystal particles are ZSM-12 zeolites with a size of about 1 to 3 hundred nanometers, and present as a sheet shape, indicating that the synthesis product is in an independent state, rather than a core-shell structure. The occurrence of two kinds of zeolites in the comparative example 1 indicates that the method is not stable enough, and the synthesized core-shell structure may be dissociated into an independent state during the preparation process.

[0087] Comparative example 2

[0088] Compared with example 1, the only difference is that the treatment temperature is a conventional high temperature when preparing the carbon-alumina-zeolite composite.

[0089] (1) Take a clean beaker, add 55 g of ZSM-12 zeolite (average particle size 1000 nm), 1100 distilled water, 1100 g of ethanol, 80 g of ammonium hydroxide solution (25% mass concentration), and mix well; place the beaker in a 50°C circulating water device; then add 5.1 g of isopropyl alcohol aluminum dropwise into the beaker at the same time; then stir for 7 h; stop stirring and stand for 6 h; then filter out the solid material and dry at 110°C for 12 h to obtain an alumina-zeolite composite.

[0090] (2) Mix the alumina-zeolite composite of the above step, 5000 g of distilled water, 15 g of iron oxide (average particle size 6 nm), and 50 g of sucrose; then evaporate the water at 100°C; then treat at 1000°C for 6 h in nitrogen; then mix with 16000 g of 2.2 wt% hydrochloric acid for 20 min; then filter the obtained sample multiple times, and then place it in an oven at 110°C for 12 h of drying to obtain a carbon-alumina-zeolite composite.

[0091] (3) Take a clean beaker, add 5.5 g of the carbon-alumina-zeolite composite and 280 g of distilled water, and mix well; then add 3 g of phosphoric acid and mix well; then add 5.1 g of triethylamine and mix well. Then load into a reaction kettle and treat at 180°C for 30 h; then filter the obtained sample multiple times, and then place it in an oven at 110°C for 12 h of drying, and finally calcine the obtained sample at 600°C in air for 3 h, and the sample is numbered as DA2.

[0092] The sample DA2 belongs to a core-shell structure and contains two kinds of crystals, which are AlPO4-5 zeolites and ZSM-12 zeolites, but the crystallinity of the AlPO4-5 zeolites is low, and the specific surface area is also low.

[0093] Comparative example 3

[0094] Compared with example 1, the only difference is that no iron oxide is added when preparing the carbon-zeolite composite.

[0095] (1) Take a clean beaker, add 55 g ZSM-12 zeolite (average particle size of 1000 nm), 1100 distilled water, 1100 g ethanol, 80 g ammonium hydroxide solution (mass concentration of 25%) and mix well; place the beaker in a circulating water device at 50°C; then add 5.1 g aluminum isopropoxide to the beaker at the same time; then stir for 7 h; stop stirring and stand for 6 h; then filter out the solid material and dry at 110°C for 12 h to obtain an alumina-zeolite composite.

[0096] (2) Mix the alumina-zeolite composite of the previous step, 5000 g distilled water, and 50 g sucrose well; then evaporate the water at 100°C; then treat at 303°C for 6 h under nitrogen; then mix with 16000 g (2.2 wt% concentration of hydrochloric acid) for 20 min; then filter the obtained sample multiple times, and then place it in an oven at 110°C for 12 h of drying to obtain a carbon-alumina-zeolite composite.

[0097] (3) Take a clean beaker, add 5.5 g carbon-alumina-zeolite composite and 280 g distilled water and mix well; then add 3 g phosphoric acid and mix well; then add 5.1 g triethylamine and mix well. Then load into a reaction kettle and treat at 180°C for 30 h; then filter the obtained sample multiple times, and then place it in an oven at 110°C for 12 h of drying, and finally calcine the obtained sample at 600°C in air for 3 h, and the sample is numbered as DA3.

[0098] Sample DA3 is in an independent state and only contains ZSM-12 zeolite, which has low crystallinity and low specific surface area.

[0099] Comparative Example 4

[0100] Compared with Example 1, the only difference is the different order of feeding.

[0101] (1) Take a clean beaker, add 55 g ZSM-12 zeolite (average particle size of 1000 nm), 1100 distilled water, 1100 g ethanol, 80 g ammonium hydroxide solution (mass concentration of 25%) and mix well; place the beaker in a circulating water device at 50°C; then add 5.1 g aluminum isopropoxide to the beaker at the same time; then stir for 7 h; stop stirring and stand for 6 h; then filter out the solid material and dry at 110°C for 12 h to obtain an alumina-zeolite composite.

[0102] (2) The alumina-zeolite composite of the previous step, 5000 g of distilled water, 15 g of iron oxide (average particle size of 6 nm), and 50 g of sucrose were mixed uniformly, and then the water was evaporated at 100°C. After that, the mixture was treated at 303°C for 6 h under nitrogen, and then mixed with 16000 g of 2.2 wt% hydrochloric acid for 20 min. The resulting sample was filtered several times and then dried in an oven at 110°C for 12 h to obtain a carbon-alumina-zeolite composite.

[0103] (3) A clean beaker was taken, and 5.5 g of the carbon-alumina-zeolite composite, 280 g of distilled water, 3 g of phosphoric acid, and 5.1 g of triethylamine were added and mixed uniformly. The mixture was then loaded into a reaction kettle and treated at 180°C for 30 h. The resulting sample was filtered several times and then dried in an oven at 110°C for 12 h, and finally calcined in air at 600°C for 3 h. The sample was numbered as DA4.

[0104] The sample DA4 was in an independent state and only contained ZSM-12 zeolite, which had a low crystallinity and a low specific surface area.

[0105] Table 1: Physicochemical properties of the samples obtained in the examples

[0106]

[0107]

[0108] *Note: In the present application, the crystallinities of the ZSM-12 zeolite and the AlPO4-5 zeolite in the sample of Example 1 were taken as 100%, the relative crystallinity of the ZSM-12 zeolite in each sample was obtained by comparing the crystallinity of the ZSM-12 zeolite in the sample with the crystallinity of the ZSM-12 zeolite in the sample of Example 1, and the relative crystallinity of the AlPO4-5 zeolite in each sample was obtained by comparing the crystallinity of the AlPO4-5 zeolite in the sample with the crystallinity of the AlPO4-5 zeolite in the sample of Example 1. The shell thicknesses given in Table 1 were all about the thicknesses.

[0109] Table 2: Physicochemical properties of the samples in the comparative examples

[0110]

[0111] *Note: In the present application, the crystallinities of the ZSM-12 zeolite and the AlPO4-5 zeolite in the sample of Example 1 were taken as 100%, the relative crystallinity of the ZSM-12 zeolite in each sample was obtained by comparing the crystallinity of the ZSM-12 zeolite in the sample with the crystallinity of the ZSM-12 zeolite in the sample of Example 1, and the relative crystallinity of the AlPO4-5 zeolite in each sample was obtained by comparing the crystallinity of the AlPO4-5 zeolite in the sample with the crystallinity of the AlPO4-5 zeolite in the sample of Example 1.

[0112] Application Example

[0113] The catalytic performance of the material was investigated by using the alkylation of naphthalene and methanol as a catalytic model reaction.

[0114] The materials prepared in Example 1-5, Comparative Example 1, Comparative Example 2 and Comparative Example 3 were respectively prepared into catalysts Cat 1-Cat 5, DCat 1, DCat 2 and DCat 3 according to the conventional method. The catalyst preparation process included the conventional ammonium ion exchange into hydrogen type zeolite, i.e. the catalyst.

[0115] The performance of the catalysts was respectively evaluated on a micro fixed bed reactor, the reaction pressure was 3.5 MPa, the reaction temperature was 330℃, the volume space velocity was 3h －1 , and the raw material was naphthalene, methanol and 1,2,4-trimethylbenzene with a molar ratio of 1:2:8. The 2,6-dimethylnaphthalene selectivity was used as the catalytic performance index. The calculation method of the 2,6-dimethylnaphthalene selectivity was the mass percentage of 2,6-dimethylnaphthalene in the reaction product. The evaluation results are shown in Table 2.

[0116] Table 2 Evaluation results

[0117] Catalyst number Sample number 2,6-dimethylnaphthalene content, % Cat1 A1 55 Cat2 A2 56 Cat3 A3 51 Cat4 A4 57 Cat5 A5 59 DCat1 DA1 21 DCat2 DA2 38 DCat3 DA3 19

Claims

1. A method for synthesizing a ZSM-12 zeolite-AlPO4-5 zeolite composite structure zeolite, comprising: (1) uniformly mixing a ZSM-12 zeolite, an aluminum source, ammonium hydroxide, an alcohol, and water; then sequentially performing dynamic treatment and static treatment; then separating and drying the solid substance to obtain an alumina-ZSM-12 zeolite composite, wherein the aluminum source is an organic aluminum alcohol; (2) mixing the alumina-ZSM-12 zeolite composite obtained in step (1), water, nano iron oxide particles, and a sugar, evaporating the water, then performing heat treatment in an inert atmosphere, then performing acid treatment, and then performing separation and drying to obtain a carbon-alumina-zeolite composite; (3) mixing water, the carbon-alumina-ZSM-12 zeolite composite obtained in step (2), phosphoric acid, and a template, performing a crystallization reaction, and then performing separation, drying, and calcination to obtain a composite zeolite; in step (1), the aluminum source is at least one of aluminum isopropoxide, aluminum butoxide, and aluminum sec-butylate; and the alcohol is at least one of ethanol, propanol, and butanol; in step (1), the mass ratio of the zeolite, the aluminum source, ammonium hydroxide, the alcohol, and water, calculated based on Al2O3, is 1:0.1-1.5:0.1-1.5:40-130:15-60; in step (1), the dynamic treatment is stirring the mixed liquid system, and the stirring time is 1-15 h; and the static treatment is allowing the mixed liquid system to be still, and the still time is 1-15 h; in step (2), the sugar is at least one of sucrose, glucose, fructose, maltose, and lactose; in step (2), the mass ratio of the ZSM-12 zeolite and the sugar is 1:0.8-6; the mass ratio of the alumina-ZSM-12 zeolite composite and water is 1:80-210; and the mass ratio of the ZSM-12 zeolite and the iron oxide is 1:0.08-0.60; in step (2), the heat treatment temperature in the inert atmosphere is 200-400°C, and the treatment time is 1-12 h; in step (2), the acid used in the acid treatment is at least one of hydrochloric acid, nitric acid, and sulfuric acid; and the mass concentration of the acid is 0.5%-5.5%; in step (2), the mass ratio of the ZSM-12 zeolite and the acid solution is 1:80-210; in step (2), the acid treatment is mixing the solid substance after the heat treatment with an acid solution, and treating at 10-40°C for 5-35 min; and in step (2), the drying temperature is 100-150°C, and the drying time is 1-20 h; in step (3), the template is at least one of triethylamine and cyclohexylamine; in step (3), the molar ratio of the phosphorus source, calculated based on P, water, and the template is 1:400-1100:0.8-5.2, wherein M is the template; and in step (3), the mass ratio of the phosphorus source, calculated based on P, and the carbon-alumina-ZSM-12 zeolite composite is 8-21:

100. The crystallization reaction temperature in step (3) is 150-220℃, and the reaction time is 15-60h; the drying temperature in step (3) is 100-150℃, and the drying time is 1-10h; the calcination in step (3) is high-temperature calcination at 400-600℃ for 1-10h.

2. The method of claim 1, wherein, The particle size of the ZSM-12 zeolite in step (1) is 400-2500nm.

3. The method of claim 1, wherein, The particle size of the ZSM-12 zeolite in step (1) is 600-2000nm.

4. The method of claim 1, wherein, The mass ratio of the zeolite, the aluminum source calculated as Al2O3, ammonium hydroxide, alcohol, and water in step (1) is 1:0.05-0.1:0.2-0.5:10-50:10-50.

5. The method of claim 1, wherein, The aluminum source in step (1) is added dropwise slowly.

6. The method of claim 1, wherein, In the dynamic treatment in step (1), the stirring time is 2-10h, and the dynamic treatment is carried out at a temperature of 30-60℃; in the static treatment, the static time is 2-10h, and the static treatment is carried out at a temperature of 30-60℃.

7. The method of claim 1, wherein, The drying condition in step (1) is drying at 100-120℃ for 5-15h.

8. The method of claim 1, wherein, The sugar in step (2) is at least one of sucrose and glucose.

9. The method of claim 1, wherein, The particle size of the nano iron oxide particles in step (2) is 2-15nm.

10. The method of claim 9, wherein, The particle size of the nano iron oxide particles in step (2) is 5-10nm.

11. The method of claim 1, wherein, The mass ratio of the ZSM-12 zeolite and the sugar in step (2) is 1:1-5; the mass ratio of the alumina-ZSM-12 zeolite composite and water is 1:100-200; and the mass ratio of the ZSM-12 zeolite and the iron oxide is 1:0.10-0.

50.

12. The method of claim 1, wherein, The temperature for evaporating the water in step (2) is 80-160℃.

13. The method of claim 12, wherein, The temperature for evaporating the water in step (2) is 100-150℃.

14. The method of claim 1, wherein, The heating treatment temperature under the inert atmosphere in step (2) is 300-350℃, and the treatment time is 2-10h.

15. The method according to claim 1 or 14, characterized in that The inert atmosphere is selected from nitrogen.

16. The method of claim 1, wherein The mass concentration of the acid in the acid treatment in step (2) is 1%-5%.

17. The method of claim 1, wherein The mass ratio of the ZSM-12 zeolite and the acid solution in step (2) is 1:100-200.

18. The method of claim 1, wherein, The acid treatment time in step (2) is 10-30min.

19. The method of claim 1, wherein, The molar ratio of the phosphorus source calculated as P, water, and the template agent in step (3) is 1:500-1500:1-5, wherein M is the template agent; and the mass ratio of the phosphorus source calculated as P and the carbon-alumina-ZSM-12 zeolite composite in step (3) is 10-20:

100.

20. The method of claim 1, wherein, The crystallization reaction temperature in step (3) is 160-210℃, and the reaction time is 20-50h.

21. The ZSM-12 zeolite-AlPO4-5 zeolite composite structure zeolite prepared according to the method of any one of claims 1-20, wherein, ZSM-12 zeolite as a core phase and AlPO4-5 zeolite as a shell phase, the specific surface area of the composite structure zeolite being 450-900 m 2 / g.

22. The composite structure zeolite of claim 21, wherein, The shell thickness of the ZSM-12 zeolite-AlPO4-5 zeolite composite structure zeolite is 20-150nm.

Images