Beta-zsm-12 composite structure zeolite and method for synthesizing the same

Abstract

The application discloses a Beta-ZSM-12 composite structure zeolite and a preparation method thereof. In the composite structure zeolite, the Beta zeolite is a core phase, and the ZSM-12 zeolite is a shell phase. The preparation method comprises the following steps: (1) uniformly mixing Beta zeolite, a silicon source, ammonium hydroxide, alcohol and water, then dynamically treating for a certain time and then statically treating, separating, drying, and obtaining a silicon oxide-Beta zeolite composite, wherein the silicon source is selected from organic silicate; (2) mixing the silicon oxide-Beta zeolite composite obtained in the step (1), nano iron oxide particles, water and sugar, evaporating water, then heating under inert conditions, then acid treating, and then separating and drying to obtain a carbon-silicon oxide-Beta zeolite composite; and (3) mixing water, the carbon-silicon oxide-Beta zeolite composite, an inorganic alkali, a template agent and an aluminum source, then loading into a reactor for crystallization reaction, and then separating, drying and calcining to obtain the Beta-ZSM-12 composite structure 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 synthesis method of a composite structure zeolite, and belongs to the field of inorganic porous material synthesis, in particular to a core-shell type Beta-ZSM-12 composite structure zeolite and a synthesis method thereof. BACKGROUND

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

[0003] CN104437606B discloses a multi-layer structure ZSM-12 molecular sieve, which comprises a core phase ZSM-12 molecular sieve and a shell layer ZSM-12 molecular sieve wrapped outside the core phase, and the core phase and the shell layer both have MTW structure, and the shell layer has a thickness of 0.5-2000nm. The preparation method comprises the following steps: (a) uniformly mixing and stirring a silicon source, an aluminum source, an alkali source, water and a template agent R according to a certain proportion to obtain a mixture I; (b) putting ZSM-12 molecular sieve into the mixture I and continuously stirring to obtain a mixture II; (c) putting the mixture II into a reaction kettle, and keeping the temperature at 80-180℃ for 12-4320h; (d) cooling the product, and drying after filtration and washing, and then calcining at 300-700℃ for 3-10h to obtain the multi-layer structure ZSM-12 molecular sieve; and (e) repeating the steps (a)-(d) at least once to obtain the multi-layer structure ZSM-12 molecular sieve.

[0004] The main problem existing in the existing technology for synthesizing core-shell structure composite zeolite is that, in the case of maintaining the integrity and crystallinity of the framework structure of Beta zeolite and ZSM-12 zeolite, either the core-shell structure cannot be formed, most of which are eutectic composite molecular sieves, or unstable core-shell structure is formed, and the core zeolite and the shell layer zeolite are easy to separate to form two independent states. SUMMARY

[0005] The present application provides a Beta-ZSM-12 composite structure zeolite and a synthesis method thereof. The Beta-ZSM-12 composite structure zeolite synthesized by the synthesis method can maintain the integrity and crystallinity of the framework structure of Beta zeolite and ZSM-12 zeolite, and the formed core-shell structure is stable.

[0006] The first aspect of the present application provides a Beta-ZSM-12 composite structure zeolite, wherein the Beta zeolite is a core phase, the ZSM-12 zeolite is a shell phase, and the shell layer has a thickness of 20-150 nm.

[0007] In the present application, the crystal framework structure elements of the Beta-ZSM-12 composite structure zeolite include silicon, aluminum, and oxygen.

[0008] In the present application, the specific surface area of the Beta-ZSM-12 composite structure zeolite is 300-800 m 2 / g.

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

[0010] (1) uniformly mixing a Beta zeolite, a silicon source, ammonium hydroxide, an alcohol, and water; then dynamically treating for a certain time and then statically treating; separating, drying, and obtaining a silicon oxide-Beta zeolite composite, wherein the silicon source is selected from organic silicate esters;

[0011] (2) mixing the silicon oxide-Beta zeolite composite obtained in step (1), nano iron oxide particles, water, and a sugar, evaporating the water, then heating under inert conditions, then acid treating, and then separating and drying to obtain a carbon-silicon oxide-Beta zeolite composite;

[0012] (3) mixing water, the carbon-silicon oxide-Beta zeolite composite, an inorganic base, a template agent, and an aluminum source, then loading into a reactor for crystallization reaction, and then separating, drying, and calcining to obtain the Beta-ZSM-12 composite structure zeolite.

[0013] In the method of the present application, the zeolite in step (1) is a Beta zeolite, and the particle size is 500-2700 nm, preferably 600-2500 nm.

[0014] In the method of the present application, the silicon source in step (1) is an organic silicate ester, and is selected from one or more of methyl silicate, ethyl silicate, and propyl silicate, preferably ethyl silicate. The silicon source decomposes amorphous silicon 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 silicon oxide on the outer surface of the core zeolite in step (1), forming a silicon oxide-Beta 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, the mass ratio of the Beta zeolite, the silicon source in terms of SiO2, 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.

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

[0018] In the method, the dynamic treatment in step (1) is stirring the mixed liquid system, and the stirring time is 1-15 h, preferably 2-10 h. The dynamic treatment is performed at a certain temperature, and the temperature is 20-70°C, preferably 30-60°C. In the dynamic treatment process, the silicon source is hydrolyzed into amorphous silicon oxide particles, which are then adsorbed on the outer surface of the core zeolite; with the extension of time, a layer of silicon oxide is gradually formed on the outer surface of the zeolite.

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

[0020] In the method, the separation in step (1) can be performed by filtration, which usually includes multiple filtrations, generally 1-10 times. The drying condition is generally drying at 100-120°C for 5-15 h.

[0021] In the method, 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 hydrocarbon in step (1).

[0022] In the method, the particle size of the nano iron oxide particles in step (2) is 2-15 nm, preferably 5-10 nm.

[0023] In the method, the mass ratio of the Beta zeolite and the sugar in step (2) is 1:0.8-6.0, preferably 1:1.0-5.0. The mass ratio of the silicon oxide-Beta zeolite composite and water is 1:80-210, preferably 1:100-200.

[0024] In the method of the present application, the mass ratio of the Beta zeolite to the iron oxide in step (2) is 1:0.08-0.60, preferably 1:0.10-0.50.

[0025] In the method of the present application, the temperature for evaporating the water in step (2) is 80-160℃, preferably 100-150℃; and the reaction time is not limited until the water is evaporated.

[0026] In the method of the present application, the heating treatment temperature under the inert condition in step (2) is 200-400℃, preferably 300-350℃, and the treatment time is 1-12h, preferably 2-10h. The heating treatment must be carried out in an inert atmosphere (such as at least one of nitrogen, argon, helium, etc., preferably nitrogen). The heating treatment converts 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 a part of the various chemical groups of the saccharides can be reserved in the carbon materials, 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, promotes the synthesis of the shell material, and can improve the catalytic performance and adsorption performance of the final material.

[0027] 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 1.0%-5.0%.

[0028] In the method of the present application, in step (2), the mass ratio of the Beta zeolite to the acid solution is 1:80-210, preferably 1:100-200.

[0029] In the method of the present application, the acid treatment in step (2) is to mix the solid material after the heating treatment with the acid solution, and treat at 10-40℃ for 5-35min, preferably 10-30min. The purpose of using the acid treatment is to remove the iron oxide in the solid material, so as to leave the mesoporous channels in the carbon material, which is beneficial to the raw materials to pass through the carbon layer to participate in the chemical reaction in the subsequent reaction process.

[0030] 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.

[0031] In the method of the present application, the drying temperature in step (2) is 100-150℃, and the drying time is 1-20h.

[0032] In the method, the adding sequence of water, carbon-silica-Beta zeolite composite, inorganic base, template agent and aluminum source in step (3) is preferably as follows: water is mixed with the carbon-silica-Beta zeolite composite first, and then the inorganic base, the template agent and the aluminum source are sequentially added.

[0033] In the method, the aluminum source in step (3) is at least one of aluminum nitrate, aluminum sulfate and aluminum chloride.

[0034] In the method, the template agent in step (3) is methyltriethylammonium chloride.

[0035] In the method, the inorganic base in step (3) is at least one of sodium hydride and potassium hydroxide.

[0036] In the method, the molar ratio of the inorganic base, the aluminum source, water and the template agent in step (3) is 2-18OH:Al2O3:2500-6500H2O:6-18M, preferably 3-16OH:Al2O3:3000-6000H2O:7-15M. M represents the template agent, the inorganic base is calculated by hydroxyl, and the aluminum source is calculated by Al2O3.

[0037] In the method, the mass ratio of the aluminum source (calculated by Al2O3) to the carbon-silica-Beta zeolite composite in step (3) is 10-30:100, preferably 15-25:100.

[0038] In the method, the crystallization reaction temperature in step (3) is 140-210°C, preferably 150-200°C, and the reaction time is 40-110h, preferably 50-100h.

[0039] In the method, the separation in step (3) can be performed by filtration, which usually includes multiple filtrations, generally 1-10 times.

[0040] In the method, the drying temperature in step (3) is 100-150°C, and the drying time is 1-10h.

[0041] In the method, the calcination in step (3) is calcination treatment at 400-600°C for 1-10h, and the calcination needs to be performed in an oxygen-containing atmosphere (such as air or oxygen). The calcination can burn the carbon material to remove it in the form of carbon dioxide, leaving only the composite zeolite.

[0042] 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, and also can be used for adsorption separation of gas and liquid.

[0043] The third aspect of the present application provides the use of the composite structure zeolite in the catalyst for preparing ethylene by hydrogenation of acetylene.

[0044] In the present application, the use is to exchange the composite structure zeolite with conventional ammonium ion, knead into shape, impregnate and load the hydrogenation active metal component to prepare the catalyst. The hydrogenation active component is preferably the Group VIII metal, wherein the Group VIII metal is preferably nickel.

[0045] In the present application, the content of the Group VIII metal in terms of oxide is 1% to 10% based on the weight of the catalyst, and the content of the composite structure zeolite is 60% to 99%.

[0046] Compared with the prior art, the present application has the following advantages:

[0047] The inventors have found that when synthesizing the Beta-ZSM-12 composite zeolite with a core-shell structure by using the traditional hydrothermal synthesis method, the Beta zeolite and the ZSM-12 zeolite often exist in an independent state instead of a stable core-shell structure, and the crystallinity of the Beta zeolite is low. It is considered that one of the main reasons is that a large amount of liquid water exists in the synthesis system during the hydrothermal synthesis process, and the 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 the Beta zeolite will decrease. The inventors have further found that by first preparing a silica-Beta zeolite composite, then preparing a carbon-silica-Beta 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-silica-Beta zeolite composite. The core-shell structure of the Beta-ZSM-12 composite structure zeolite obtained after crystallization is tight and not easy to separate, and the framework structures of the Beta zeolite and the ZSM-12 zeolite are complete. The possible mechanism analysis is as follows: a thin layer of silica film is first formed on the surface of the Beta 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 chemical groups of the sugar substances in the carbon material at a relatively low treatment temperature. The carbon-silica-Beta zeolite material is a solid composite material with a size of tens or even hundreds of microns, and the silica-Beta 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 react with the silica on the surface of the core zeolite as a silicon source to occur crystallization. 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. Moreover, the framework structures of the Beta zeolite and the ZSM-12 zeolite are complete, and the various chemical groups on the carbon material are beneficial to improve the crystallinity and catalytic performance of the ZSM-12 zeolite.

[0048] The ethylene catalyst prepared by using the composite structure zeolite of the present application has high activity and selectivity, and the content of ethylene in the obtained product is significantly increased. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 The scanning electron microscope photograph of sample A1 obtained in Example 1 is shown in Figure 1.

[0050] Figure 2 The XRD graph of sample A1 obtained in Example 1 is shown in Figure 2.

[0051] Figure 3 The XRD pattern of sample DA1 obtained for Comparative Example 1 is shown in Figure 1.

[0052] Figure 4 The scanning electron microscope photograph of sample DA1 obtained for Comparative Example 1 is shown in Figure 2. DETAILED DESCRIPTION

[0053] 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.

[0054] 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 vacuum treated at 300℃ for more than 4h. The total specific surface area and other parameters are calculated according to the BET formula.

[0055] 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 JSM-6301F of Japan Electronics Corporation, with working voltage of 20kV, working distance of 15mm, and resolution of 1.5nm.

[0056] The crystal phase and crystallinity structure of the composite structure zeolite of the present application are characterized by X-ray diffraction, which is tested by a D / max2500 X-ray diffractometer of Japan Rigaku, with Cu target, Kα radiation source, graphite monochromator, tube voltage of 40kV, tube current of 80mA, scanning range of 5°-40°, step length of 0.1°, and scanning speed of 1° / min. 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, with instrument model of JEM-2200FS field emission ultra-high-resolution transmission electron microscope, acceleration voltage of 200kV, and point resolution of 0.19nm.

[0057] Example 1

[0058] (1) A clean beaker was taken, 60g of Beta zeolite (average particle size of 1300nm), 1000g of distilled water, 1000g of ethanol, and 60g of ammonium hydroxide solution (concentration of 25wt%) were added and mixed uniformly; the beaker was placed in a 50℃ circulating water device; then 11.7g of tetraethyl orthosilicate was added dropwise into the beaker; then stirring was performed for 5h; the stirring was stopped and the beaker was left to stand for 5h; then the solid material was filtered out and dried at 110℃ for 12h to obtain a silica-Beta zeolite composite.

[0059] (2) Mix the silica-Beta zeolite complex from the previous step, 8000g of distilled water, 15g of iron oxide (average particle size of 6nm), and 150g of sucrose evenly; then evaporate the water at 100℃; then treat it in nitrogen at 313℃ for 5h; then mix it with 16000g (2.1wt% 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-silica-Beta zeolite complex.

[0060] (3) Take a clean beaker, add 65g of distilled water and 14.5g of carbon-silica-Beta zeolite complex and mix well; then add 0.15g of sodium hydroxide and mix well; then add 1.3g of methyltriethylammonium chloride and mix well; then add 0.41g of aluminum sulfate and mix well. Then put it into a reaction vessel and treat it at 170℃ for 90h; 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 400℃ for 10h. The obtained sample is numbered A1.

[0061] 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 ZSM-12 zeolite and Beta zeolite. According to Table 1, both types of crystals have high crystallinity and high specific surface area.

[0062] 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 900 nm and consists of irregular particles. The outer shell is rough, consisting of a coarse ZSM-12 zeolite shell with a thickness of approximately 110 nm.

[0063] Example 2

[0064] (1) Take a clean beaker, add 50g Beta zeolite (average particle size of 900nm), 460g distilled water, 500g ethanol, and 40g ammonium hydroxide solution (concentration of 25wt%) and mix well; place the beaker in a circulating water device at 30℃; then add 8.7g tetraethyl orthosilicate dropwise to the beaker; stir for 2h; stop stirring and let stand for 2h; then filter out the solid material and dry at 110℃ for 12h to obtain the silica-Beta zeolite composite.

[0065] (2) Take a clean beaker, add 5000 g distilled water, 10 g iron oxide (average particle size of 6 nm), 50 g sucrose, and mix well; then evaporate the water at 100°C; then treat at 300°C for 10 h under nitrogen; then treat with 10000 g (1 wt% concentration of hydrochloric acid) for 10 min; then filter the resulting sample several times, and then place it in an oven at 110°C for 12 h to obtain a carbon-silicon oxide-Beta zeolite composite.

[0066] (3) Take a clean beaker, add 65 g distilled water, 14.5 g carbon-silicon oxide-Beta zeolite composite, and mix well; then add 0.15 g sodium hydroxide and mix well; then add 1.3 g methyl triethyl ammonium chloride and mix well; then add 0.41 g aluminum sulfate and mix well. Then put it into a reaction kettle and treat at 150°C for 100 h; then filter the resulting sample several times, and then place it in an oven at 110°C for 12 h, and finally calcine the sample at 400°C in air for 10 h, and the resulting sample is numbered A2.

[0067] Sample A2 belongs to a core-shell structure and contains two crystals, ZSM-12 zeolite and Beta zeolite, both of which have high crystallinity and high specific surface area.

[0068] Example 3

[0069] (1) Take a clean beaker, add 50 g Beta zeolite (average particle size of 1000 nm), 2400 g distilled water, 2500 g ethanol, and 100 g ammonium hydroxide solution (concentration of 25 wt%), and mix well; place the beaker in a circulating water device at 60°C; then add 17 g tetraethyl orthosilicate to the beaker while stirring; then stir for 10 h; stop stirring and let it stand for 10 h; then filter out the solid material and dry it at 110°C for 12 h to obtain a silicon oxide-Beta zeolite composite.

[0070] (2) Take a clean beaker, add 5000 g distilled water, 10 g iron oxide (average particle size of 6 nm), 50 g sucrose, and mix well; then evaporate the water at 100°C; then treat at 300°C for 10 h under nitrogen; then treat with 10000 g (1 wt% concentration of hydrochloric acid) for 10 min; then filter the resulting sample several times, and then place it in an oven at 110°C for 12 h to obtain a carbon-silicon oxide-Beta zeolite composite.

[0071] (3) Take a clean beaker, add 65 g distilled water, 14.5 g carbon-silica-Beta zeolite composite, mix well; add 0.15 g sodium hydroxide, mix well; add 1.3 g methyl triethyl ammonium chloride, mix well; then add 0.41 g aluminum nitrate nonahydrate, mix well. Then put it into the reaction kettle and treat at 170°C for 75h; then filter the obtained sample several times, then place it in an oven at 110°C for 12h, and finally calcine it at 400°C in air for 10h, the obtained sample is numbered as A4.

[0072] Sample A4 belongs to a core-shell structure, containing two crystals, ZSM-12 zeolite and Beta zeolite respectively, both of which have high crystallinity and high specific surface area.

[0073] Example 4

[0074] (1) Take a clean beaker, add 52 g Beta zeolite (average particle size 800 nm), 1100 g distilled water, 1300 g ethanol, 60 g ammonium hydroxide solution (concentration 25wt%), mix well; place the beaker in a circulating water device at 55°C; then add 10.7 g tetraethyl orthosilicate to the beaker while stirring; then stir for 5h; stop stirring and let it stand for 5h; then filter out the solid material and dry it at 110°C for 12h to obtain a silica-Beta zeolite composite.

[0075] (2) Mix the silica-Beta zeolite composite of the above step, 8100 g distilled water, 20.5 g iron oxide (average particle size 7 nm), 150 g glucose, mix well; then evaporate the water at 100°C; then treat at 320°C for 5h in nitrogen; then mix with 15500 g (3.7wt% concentration of hydrochloric acid) for 20min; then filter the obtained sample several times, then place it in an oven at 110°C for 12h to obtain a carbon-silica-Beta zeolite composite.

[0076] (3) Take a clean beaker, add 65 g distilled water, 14.5 g carbon-silica-Beta zeolite composite, mix well; add 0.15 g sodium hydroxide, mix well; add 1.3 g methyl triethyl ammonium chloride, mix well; then add 0.41 g aluminum nitrate nonahydrate, mix well. Then put it into the reaction kettle and treat at 170°C for 75h; then filter the obtained sample several times, then place it in an oven at 110°C for 12h, and finally calcine it at 400°C in air for 10h, the obtained sample is numbered as A4.

[0077] Sample A4 belongs to a core-shell structure, containing two crystals, ZSM-12 zeolite and Beta zeolite respectively, both of which have high crystallinity and high specific surface area.

[0078] Example 5

[0079] (1) Take a clean beaker, add 60 g of Beta zeolite (average particle size of 1100 nm), 1200 g of distilled water, 1200 g of propanol, 65 g of ammonium hydroxide solution (concentration of 25 wt%) and mix well; place the beaker in a circulating water device at 55°C; then add 12.5 g of tetraethyl orthosilicate to the beaker while stirring; then stir for 5 h; stop stirring and let stand for 5 h; then filter out the solid material and dry at 110°C for 12 h to obtain a silica-Beta zeolite composite.

[0080] (2) Mix the silica-Beta zeolite composite from the previous step, 8500 g of distilled water, 19.5 g of iron oxide (average particle size of 7 nm), 120 g of glucose, and mix well; then evaporate the water at 100°C; then treat in nitrogen at 313°C for 6.5 h; then mix with 13500 g of 3.1 wt% hydrochloric acid for 26 min; then filter the resulting sample multiple times, and then place in an oven at 110°C for 12 h to obtain a carbon-silica-Beta zeolite composite.

[0081] (3) Take a clean beaker, add 65 g of distilled water, 14.5 g of carbon-silica-Beta zeolite composite and mix well; then add 0.12 g of sodium hydroxide and mix well; then add 1.51 g of methyltriethylammonium chloride and mix well; then add 0.45 g of aluminum sulfate and mix well. Then place in a reaction kettle and treat at 175°C for 70 h; then filter the resulting sample multiple times, and then place in an oven at 110°C for 12 h, and finally calcine the sample at 450°C in air for 7 h, and the resulting sample is numbered A5.

[0082] Sample A5 is a core-shell structure and contains two crystals, ZSM-12 zeolite and Beta zeolite, both of which have high crystallinity and high specific surface area.

[0083] Comparative Example 1

[0084] Compared with Example 1, the only difference is that no carbon-silica-zeolite material is prepared.

[0085] Take a clean beaker, add 65 g of distilled water, 10 g of Beta zeolite (average particle size of 1300 nm) and mix well; then add 0.15 g of sodium hydroxide and mix well; then add 1.3 g of methyltriethylammonium chloride and mix well; then add 0.41 g of aluminum sulfate and mix well; then add 11.7 g of tetraethyl orthosilicate to the beaker. Then place in a reaction kettle and treat at 170°C for 90 h; then filter the resulting sample multiple times, and then place in an oven at 110°C for 12 h, and finally calcine the sample at 400°C in air for 10 h, and the resulting sample is numbered DA1. The XRD of sample DA1 is shown in Figure 1. Figure 3It is composed of two crystal phases: ZSM-12 zeolite and Beta zeolite.

[0086] The XRD pattern of sample DA1 is shown below. Figure 3 As shown in the figure, the composite material contains two types of crystals, namely ZSM-12 zeolite and Beta zeolite. According to Table 2, Beta zeolite has a low crystallinity and a slightly lower specific surface area.

[0087] Scanning electron microscope image of sample DA1 is shown below. Figure 4 ,Depend on Figure 4 As can be seen, the sample contains two types of zeolite. ZSM-12 has larger crystal particles, approximately 1 micrometer in size, with relatively sharp crystal edges; Beta zeolite has smaller crystal particles, approximately 1 to 500 nanometers in size, with relatively rounded crystal edges. This indicates that the synthesized product is in an independent state, rather than a core-shell structure. The fact that Comparative Example 1 shows two types of zeolite existing independently suggests that the method is not stable enough, and it is possible that the synthesized core-shell structure dissociates into an independent state during the preparation process.

[0088] Comparative Example 2

[0089] Compared with Example 1, the only difference is that iron oxide was not added when preparing the carbon-silica-zeolite composite, and aluminum hydroxide was used as the aluminum source when preparing the core-shell zeolite.

[0090] (1) Take a clean beaker, add 60g Beta zeolite (average particle size of 1300nm), 1000g distilled water, 1000g ethanol, and 60g ammonium hydroxide solution (concentration of 25wt%) and mix well; place the beaker in a circulating water device at 50℃; then add 11.7g tetraethyl orthosilicate dropwise to the beaker; stir for 5h; stop stirring and let stand for 5h; then filter out the solid material and dry at 110℃ for 12h to obtain the silica-Beta zeolite composite.

[0091] (2) Mix the silica-Beta zeolite complex from the previous step, 8000g of distilled water, and 150g of sucrose evenly; then evaporate the water at 100℃; then treat it in nitrogen at 313℃ for 5h; then mix it with 16000g (2.1wt% hydrochloric acid) for 20min; then filter the obtained sample several times, and then dry it in an oven at 110℃ for 12h to obtain the carbon-silica-Beta zeolite complex.

[0092] (3) Take a clean beaker, add 65 g distilled water, 14.5 g carbon-silica-Beta zeolite complex, mix well; add 0.15 g sodium hydroxide, mix well; add 1.3 g methyl triethyl ammonium chloride, mix well; then add 0.15 g aluminum hydroxide, mix well. Then put into the reaction kettle and treat at 170°C for 90h; then filter the obtained sample several times, then place in an oven at 110°C for 12h, and finally calcine at 400°C in air for 10h, the obtained sample is numbered as DA2.

[0093] Sample DA2 belongs to an independent state, only containing Beta zeolite, with low crystallinity and low specific surface area.

[0094] Comparative Example 3

[0095] Compared with Example 1, the only difference is that the treatment temperature is a conventional high temperature when preparing the carbon-silica-zeolite complex.

[0096] (1) Take a clean beaker, add 60 g Beta zeolite (average particle size 1300 nm), 1000 g distilled water, 1000 g ethanol, 60 g ammonium hydroxide solution (concentration 25wt%), mix well; place the beaker in a circulating water device at 50°C; then add 11.7 g tetraethyl orthosilicate to the beaker at the same time; then stir for 5h; stop stirring and stand for 5h; then filter out the solid material and dry at 110°C for 12h to obtain a silica-Beta zeolite complex.

[0097] (2) Mix the silica-Beta zeolite complex of the above step, 8000 g distilled water, 15 g iron oxide (average particle size 6 nm), 150 g sucrose, mix well; then evaporate the water at 100°C; then treat at 1000°C for 5h in nitrogen; then mix with 16000 g (2.1wt% concentration of hydrochloric acid) for 20min; then filter the obtained sample several times, then place in an oven at 110°C for 12h to obtain a carbon-silica-Beta zeolite complex.

[0098] (3) Take a clean beaker, add 65 g distilled water, 14.5 g carbon-silica-Beta zeolite complex, mix well; add 0.15 g sodium hydroxide, mix well; add 1.3 g methyl triethyl ammonium chloride, mix well; then add 0.41 g aluminum sulfate, mix well. Then put into the reaction kettle and treat at 170°C for 90h; then filter the obtained sample several times, then place in an oven at 110°C for 12h, and finally calcine at 400°C in air for 10h, the obtained sample is numbered as DA3.

[0099] Sample DA3 belongs to a core-shell structure, containing two kinds of crystals, Y zeolite and Beta zeolite, and has a low specific surface area.

[0100] Comparative Example 4

[0101] The difference compared with Example 1 is that no iron oxide is added when preparing the carbon-zeolite composite.

[0102] (1) Take a clean beaker, add 60 g of Beta zeolite (average particle size of 1300 nm), 1000 g of distilled water, 1000 g of ethanol, 60 g of ammonium hydroxide solution (concentration of 25 wt%), and mix well; place the beaker in a circulating water device at 50°C; then add 11.7 g of tetraethyl orthosilicate dropwise; then stir for 5 h; stop stirring and let stand for 5 h; then filter out the solid material and dry at 110°C for 12 h to obtain a silica-Beta zeolite composite.

[0103] (2) Mix the silica-Beta zeolite composite from the previous step, 8000 g of distilled water, and 150 g of sucrose well; then evaporate the water at 100°C; then treat at 313°C for 5 h under nitrogen; then mix with 16000 g of 2.1 wt% hydrochloric acid for 20 min; then filter the resulting sample multiple times, and then place it in an oven at 110°C for 12 h of drying to obtain a carbon-silica-Beta zeolite composite.

[0104] (3) Take a clean beaker, add 65 g of distilled water, 14.5 g of carbon-silica-Beta zeolite composite, and mix well; then add 0.15 g of sodium hydroxide and mix well; then add 1.3 g of methyltriethylammonium chloride and mix well; then add 0.41 g of aluminum sulfate and mix well. Then load into a reaction kettle and treat at 170°C for 90 h; then filter the resulting sample multiple times, and then place it in an oven at 110°C for 12 h of drying, and finally calcine the sample at 400°C in air for 10 h, and the resulting sample is numbered as DA4.

[0105] Sample DA4 is in an independent state and only contains Beta zeolite, which has low crystallinity and low specific surface area.

[0106] Comparative Example 5

[0107] The difference compared with Example 1 is that the order of adding materials is different.

[0108] (1) Take a clean beaker, add 60 g of Beta zeolite (average particle size of 1300 nm), 1000 g of distilled water, 1000 g of ethanol, 11.7 g of tetraethyl orthosilicate, and 60 g of ammonium hydroxide solution (concentration of 25 wt%), and mix well; place the beaker in a circulating water device at 50°C; then stir for 5 h; stop stirring and let stand for 5 h; then filter out the solid material and dry at 110°C for 12 h to obtain a silica-Beta zeolite composite.

[0109] (2) The silicon oxide-Beta zeolite composite of the above step, 8000 g of distilled water, 15 g of iron oxide (average particle size of 6 nm), and 150 g of sucrose were mixed uniformly, and then the water was evaporated at 100°C. After that, the mixture was treated at 313°C for 5 h under nitrogen, and then mixed with 16000 g of hydrochloric acid (2.1 wt% concentration) 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-silicon oxide-Beta zeolite composite.

[0110] (3) A clean beaker was taken, 65 g of distilled water, 14.5 g of the carbon-silicon oxide-Beta zeolite composite, 0.15 g of sodium hydroxide, 1.3 g of methyl triethyl ammonium chloride, and 0.41 g of aluminum sulfate were mixed uniformly. After that, the mixture was put into a reaction kettle and treated at 170°C for 90 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 400°C for 10 h. The sample was numbered as DA5.

[0111] The sample DA5 was in an independent state and contained only Beta zeolite, which had a low crystallinity and a low specific surface area.

[0112] Table 1: Physicochemical properties of the samples of each example

[0113]

[0114] *Note: In the present application, the crystallinity of the Beta zeolite and the ZSM-12 zeolite of the sample in Example 1 was taken as 100%, the relative crystallinity of the Beta zeolite of all samples was obtained by comparing the crystallinity of the Beta zeolite of the sample with the crystallinity of the Beta zeolite of the sample in Example 1, and the relative crystallinity of the ZSM-12 zeolite of all samples was obtained by comparing the crystallinity of the ZSM-12 zeolite of the sample with the crystallinity of the ZSM-12 zeolite of the sample in Example 1. The shell thickness given in Table 1 was about the thickness.

[0115] Table 2: Physicochemical properties of the samples of each comparative example

[0116]

[0117] Note: In the present application, the crystallinity of the Beta zeolite and the ZSM-12 zeolite of the sample in Example 1 was taken as 100%, the relative crystallinity of the Beta zeolite of all samples was obtained by comparing the crystallinity of the Beta zeolite of the sample with the crystallinity of the Beta zeolite of the sample in Example 1, and the relative crystallinity of the ZSM-12 zeolite of all samples was obtained by comparing the crystallinity of the ZSM-12 zeolite of the sample with the crystallinity of the ZSM-12 zeolite of the sample in Example 1.

[0118] Application Example

[0119] The catalytic performance of the materials was investigated by catalytic acetylene.

[0120] The materials of Example 1-5, Comparative Example 1, Comparative Example 3 and Comparative Example 4 were prepared into catalysts Cat1-Cat5, DCat1, DCat3 and DCat4 respectively according to the conventional method. The catalyst preparation process included conventional ammonium ion exchange, isometric volume impregnation loading of metal nickel, and the nickel metal content in the finally prepared catalyst was 3wt%.

[0121] The performance of the catalysts was evaluated on a micro fixed bed reactor, the reaction temperature was 350℃, the space velocity was 27L(g-h) －1 , the reaction temperature was 250℃, and the raw material was a mixture of hydrogen and acetylene (volume ratio 2:1). The ethylene selectivity was used as the catalytic performance index. The calculation method of ethylene selectivity was the mass percentage of ethylene in the gas phase product in the reaction product. The evaluation results are shown in Table 2.

[0122] Table 2 Evaluation results

[0123] Catalyst number Sample number Ethylene content, % Cat 1 A1 59 Cat 2 A2 57 Cat 3 A3 55 Cat 4 A4 59 Cat 5 A5 58 DCat 1 DA 1 15 DCat 3 DA 3 39 DCat 4 DA 4 10

Claims

1. A method for synthesizing a Beta-ZSM-12 composite zeolite, comprising: (1) Mix Beta zeolite, silicon source, ammonium hydroxide, alcohol and water evenly; After dynamic processing for a certain period of time, static processing is then performed. After separation and drying, a silica-Beta zeolite complex was obtained, wherein the silicon source was selected from organosilicates; (2) The silica-Beta zeolite complex obtained in step (1), nano iron oxide particles, water and sugar are mixed, the water is evaporated, and then heated under inert conditions. After acid treatment, it is separated and dried to produce carbon-silica-Beta zeolite complex. (3) Water, carbon-silica-Beta zeolite composite, inorganic alkali, template agent and aluminum source are mixed and then loaded into a reactor for crystallization reaction. After separation, drying and calcination, Beta-ZSM-12 composite zeolite is obtained. The silicon source mentioned in step (1) is an organosilicone ester, selected from one or more of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate; the alcohol is at least one of ethanol, propanol, and butanol. The mass ratio of Beta zeolite, silicon source (calculated as SiO2), ammonium hydroxide, alcohol, and water mentioned in step (1) is 1:0.1~1.5:0.1~1.5:40~130:15~60; The sugar mentioned in step (2) is at least one of sucrose, glucose, fructose, maltose, and lactose; In step (2), the mass ratio of Beta zeolite to sugar is 1:0.8~6.0; the mass ratio of the silica-Beta zeolite composite to water is 1:80~210; and the mass ratio of Beta zeolite to iron oxide is 1:0.08~0.

60. The inert heating treatment temperature described in step (2) is 300~900℃, and the treatment time is 1~12h; 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% to 5.5%; in step (2), the mass ratio of Beta zeolite to acid solution is 1:80 to 210. The acid treatment described in step (2) involves mixing the heat-treated solid with acid and treating it at 10~40℃ for 5~35 minutes. The aluminum source mentioned in step (3) is at least one of aluminum nitrate, aluminum sulfate, and aluminum chloride; the template agent is methyltriethylammonium chloride; and the inorganic base is selected from at least one of sodium hydrochloride and potassium hydroxide. In step (3), the molar ratio of inorganic base, aluminum source, water and template agent is 2~18 OH:Al2O3:2500~6500 H2O:6~18 M; where M represents template agent, inorganic base is calculated as hydroxyl group, and aluminum source is calculated as Al2O3; in step (3), the mass ratio of aluminum source (calculated as Al2O3) to carbon-silica-Beta zeolite composite is 10~30:

100. The crystallization reaction conditions in step (3) are as follows: the crystallization reaction temperature is 140~210℃ and the reaction time is 40~110h; The drying conditions described in step (1) are drying at 100~120℃ for 5~15h; the drying temperature described in step (2) is 100~150℃ and the drying time is 1~20h; the drying temperature described in step (3) is 100~150℃ and the drying time is 1~10h; the calcination described in step (3) is calcination treatment at 400~600℃ for 1~10h.

2. The synthesis method according to claim 1, characterized in that, The zeolite mentioned in step (1) is Beta zeolite with a particle size of 500~2700 nm.

3. The synthesis method according to claim 2, characterized in that, The zeolite mentioned in step (1) is Beta zeolite with a particle size of 600~2500 nm.

4. The synthesis method according to claim 1, characterized in that, The silicon source mentioned in step (1) is tetraethyl orthosilicate.

5. The synthesis method according to claim 1, characterized in that, The mass ratio of Beta zeolite, silicon source (calculated as SiO2), ammonium hydroxide, alcohol, and water in step (1) is 1:0.05~0.1:0.2~0.5:10~50:10~50.

6. The synthesis method according to claim 1, characterized in that, In step (1), the silicon source is added slowly drop by drop.

7. The synthesis method according to claim 1, characterized in that, The dynamic treatment in step (1) involves stirring the mixed liquid system for 1 to 15 hours; the dynamic treatment is carried out at a temperature of 20 to 70°C.

8. The synthesis method according to claim 1, characterized in that, The dynamic treatment in step (1) involves stirring the mixed liquid system for 2 to 10 hours; the dynamic treatment is carried out at a temperature of 30 to 60°C.

9. The synthesis method according to claim 1, characterized in that, The static treatment in step (1) involves allowing the mixed liquid system to stand still for 1 to 15 hours; the standing is carried out at a temperature of 20 to 70°C.

10. The synthesis method according to claim 1, characterized in that, The static treatment in step (1) involves allowing the mixed liquid system to stand still for 2 to 10 hours; the standing is carried out at a temperature of 30 to 60°C.

11. The synthesis method according to claim 1, characterized in that, The sugar mentioned in step (2) is at least one of sucrose and glucose.

12. The synthesis method according to claim 1, characterized in that, The particle size of the nano-iron oxide particles mentioned in step (2) is 2~15nm.

13. The synthesis method according to claim 12, characterized in that, The particle size of the nano-iron oxide particles mentioned in step (2) is 5~10nm.

14. The synthesis method according to claim 1, characterized in that, In step (2), the mass ratio of Beta zeolite to sugar is 1:1.0~5.0; the mass ratio of the silica-Beta zeolite composite to water is 1:100~200; and / or, in step (2), the mass ratio of Beta zeolite to iron oxide is 1:0.10~0.

50.

15. The synthesis method according to claim 1, characterized in that, The temperature for evaporating water in step (2) is 80~160℃.

16. The synthesis method according to claim 15, characterized in that, The temperature for evaporating water in step (2) is 100~150℃.

17. The synthesis method according to claim 1, characterized in that, The inert heating treatment temperature described in step (2) is 300~500℃, and the treatment time is 2~10h.

18. The synthesis method according to claim 1, characterized in that, The mass concentration of the acid mentioned in step (2) is 1.0% to 5.0%.

19. The synthesis method according to claim 1, characterized in that, In step (2), the mass ratio of Beta zeolite to acid is 1:100~200.

20. The synthesis method according to claim 1, characterized in that, The acid treatment time in step (2) is 10~30 min.

21. The synthesis method according to claim 1, characterized in that, In step (3), the molar ratio of inorganic base, aluminum source, water and template agent is 3~16 OH: Al2O3: 3000~6000 H2O: 7~15 M; where M represents template agent, inorganic base is calculated as hydroxyl group, aluminum source is calculated as Al2O3; and / or, in step (3), the mass ratio of aluminum source (calculated as Al2O3) to carbon-silica-Beta zeolite composite is 15~25:

100.

22. The synthesis method according to claim 1, characterized in that, The crystallization reaction conditions in step (3) are as follows: the crystallization reaction temperature is 150~200℃ and the reaction time is 50~100h.

23. The Beta-ZSM-12 composite zeolite prepared by any one of claims 1-22, wherein the Beta zeolite is the core phase, the ZSM-12 zeolite is the shell phase, and the shell thickness is 20~150 nm.

24. The composite zeolite according to claim 23, characterized in that, The specific surface area of ​​the Beta-ZSM-12 composite zeolite is 300~800 m². 2 / g.

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