A method for the synthesis of a y-zeolite-beta-zeolite composite structure zeolite

Abstract

The application discloses a synthesis method of Y zeolite-Beta zeolite composite structure zeolite. The composite structure zeolite is a core-shell structure, wherein Y zeolite is the core, and Beta zeolite is the shell layer. The method comprises the following steps: (1) mixing Y zeolite, nano iron oxide particles, water and saccharides, evaporating water, and then heating under inert conditions, and then performing acid treatment, and then performing separation and drying to prepare a carbon-Y zeolite composite; (2) mixing water and a silicon source, and then sequentially adding the carbon-Y zeolite composite, an inorganic alkali, a template agent and an aluminum source, uniformly mixing, and crystallizing, and then performing separation, drying and calcination to obtain the composite structure zeolite. The silicon source is a soluble silicon salt, and the aluminum source is a soluble aluminum salt. The composite structure zeolite synthesized by the method is a core-shell composite zeolite with stable structure, can be used as a catalyst or a catalyst carrier, and can also be used for adsorption and separation of gas and liquid.

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 synthesis method of a core-shell Y zeolite-Beta zeolite composite structure zeolite. BACKGROUND

[0002] The Y-Beta composite zeolite has both Y zeolite and Beta zeolite crystal phases, and integrates the advantages of both Y zeolite and Beta zeolite, and can be applied to various catalytic reactions. Therefore, the Y-Beta composite zeolite is widely studied in the field of zeolite synthesis.

[0003] CN200410012333.2 discloses a kind of bimodal zeolite molecular sieve and preparation method. Using ordered synthesis method, first, using sodium silicate, silica sol, sodium metaaluminate, distilled water, sodium hydroxide, concentrated sulfuric acid as raw materials, according to certain material ratio, Y zeolite is initially synthesized; then it is mixed with tetraethylammonium bromide solution dissolved with ammonia water, finally a certain amount of silica sol is added to fully stir to make it uniform, crystallization is carried out at 130-140 DEG C for 4-7 days, and the template agent is removed by washing, drying and calcination, and finally a kind of composite zeolite molecular sieve with Y / β bimodal structure is obtained.

[0004] CN102442680 B discloses a kind of Y-Beta composite molecular sieve and rapid synthesis method. The method comprises the following steps: first, sodium hydroxide and tetraethylammonium bromide are dissolved in deionized water, and then ammonia water is selectively added; second, the mixed solution is heated to 40-100 DEG C, and Y-type molecular sieve powder is added to the solution of the first step after uniform stirring under the condition of keeping the temperature, to form a uniform mixture; third, the silicon source is slowly added to the mixture of the second step to obtain a uniform reaction mixture gel system, and then crystallization is carried out at 135-145 DEG C for 72-90 hours to obtain Y-Beta composite molecular sieve.

[0005] Y-Beta core-shell structure composite zeolite is a kind of Y-Beta composite zeolite with special structure, Y zeolite as the core is similar to the yolk in the center of the material, and Beta zeolite as the shell layer is similar to the protein wrapped in the outer layer of the core. The main problem existing in the existing technology for synthesizing Y-Beta core-shell structure composite zeolite is that, under the condition of keeping the framework structure of Y zeolite and Beta zeolite intact, 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.

[0006] CN102909065B discloses a synthesis method of Y-Beta composite molecular sieve with core-shell structure. The method comprises: (1) dissolving sodium hydroxide, tetraethylammonium bromide and ammonia water in water to obtain a solution; (2) adding Y-type molecular sieve powder into the solution and treating at 40-100 DEG C for 2-12 hours; (3) filtering and drying the solution of step (2) to obtain treated Y-type molecular sieve powder; (4) mixing sodium hydroxide, an aluminum source, tetraethylammonium bromide, ammonia water and water to obtain a mixed solution; (5) adding the treated Y-type molecular sieve powder into the mixed solution prepared in step (4), stirring uniformly, then adding a silicon source, stirring uniformly to obtain a reaction mixture gel system, and then performing a crystallization reaction to obtain a composite molecular sieve product. The method is to destroy the complete structure of the surface of NaY-type molecular sieve by pretreatment, form a large number of defect sites, and introduce a template agent in the treatment process, so that the defect sites of the surface are ion exchanged, and thus the framework structure of the core Y molecular sieve of the Y-Beta composite molecular sieve with core-shell structure is partially destroyed. SUMMARY

[0007] In view of the deficiencies of the prior art, the present application provides a synthesis method of Y zeolite-Beta zeolite composite structure zeolite. The composite structure zeolite synthesized by the method can maintain the integrity and crystallinity of the framework structure of Y zeolite and Beta zeolite, and has a core-shell type composite zeolite with a tightly combined core-shell structure and stable structure.

[0008] The first aspect of the present application provides a synthesis method of Y zeolite-Beta zeolite composite structure zeolite, the composite structure zeolite being of a core-shell type structure in which Y zeolite is the core and Beta zeolite is the shell layer, and the method comprising the following steps:

[0009] (1) mixing Y zeolite, water, nano iron oxide particles and a saccharide, evaporating the water, then heating under an inert atmosphere, followed by acid treatment, and then separating and drying to prepare a carbon-Y zeolite composite;

[0010] (2) mixing water and a silicon source, then sequentially adding the carbon-Y zeolite composite, an inorganic base, a template agent and an aluminum source, mixing uniformly, crystallizing, and then separating, drying and calcining to obtain a composite structure zeolite;

[0011] The silicon source is a soluble silicon salt, and the aluminum source is a soluble aluminum salt.

[0012] In the method of the present application, the saccharide in step (1) is at least one of sucrose, glucose, fructose, maltose and lactose, and is preferably at least one of sucrose and glucose. The saccharide is converted into carbon material by dehydration and dehydrogenation of hydrocarbons in step (1).

[0013] The Y zeolite in step (1) has a particle size ranging from 500 to 3500 nm, preferably from 600 to 3000 nm. The nano iron oxide particles have a particle size ranging from 2 to 15 nm, preferably from 5 to 10 nm.

[0014] In the method of the present application, the mass ratio of the Y zeolite to the sugar in step (1) is 1:0.8-6.0, preferably 1:1.0-5.0. The mass ratio of the Y zeolite to water is 1:80-210, preferably 1:100-200.

[0015] In the method of the present application, the mass ratio of the Y zeolite to the iron oxide in step (1) is 1:0.08-0.60, preferably 1:0.10-0.50.

[0016] In the method of the present application, the temperature for evaporating the water in step (1) is 80-160℃, preferably 100-150℃. The reaction time is not limited until the water is evaporated.

[0017] In the method of the present application, the temperature for heating treatment in an inert atmosphere in step (1) is 200-400℃, preferably 300-350℃, and the treatment time is 1-12 h, preferably 2-10 h. The heating treatment in an inert atmosphere can be carried out in an atmosphere of at least one of nitrogen, argon, helium, etc., preferably nitrogen. The heating treatment in an inert atmosphere can convert the sugar into carbon material through dehydration and dehydrogenation, and the Y zeolite can be wrapped in the carbon material. Compared with the calcination temperature for converting the sugar into carbon material with stable physical and chemical properties in the conventional method, the relatively low treatment temperature in the present application can retain a part of the chemical groups of the sugar in the carbon material, so that the carbon material has certain chemical activity, which is beneficial to the participation of the carbon material 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.

[0018] In the method of the present application, the acid used in the acid treatment in step (1) 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%.

[0019] In the method of the present application, the mass ratio of the Y zeolite to the acid solution in step (1) is 1:80-210, preferably 1:100-200.

[0020] In the method of the present application, the acid treatment in step (1) is to mix the solid material after the heating treatment with the acid solution, and the mixture is treated at 10-40℃ for 5-35 min, preferably 10-30 min. The purpose of the acid treatment is to remove the iron oxide in the solid material, so that the mesoporous channels are left in the carbon material, which is beneficial to the raw materials to pass through the carbon layer and participate in the chemical reaction in the subsequent reaction process.

[0021] In the method of the present application, the separation in step (1) can be performed by filtration, usually including multiple filtrations, typically 1-10 times.

[0022] In the method of the present application, the drying temperature in step (1) is 100-150℃, and the drying time is 1-20h.

[0023] In the method of the present application, the feeding sequence in step (2) is as follows: first, mix water and silicon source, then add the carbon-Y zeolite composite and mix uniformly, then add inorganic base and mix uniformly, then add template agent and mix uniformly, and then add aluminum source and mix uniformly. Such a feeding sequence can ensure that all materials pass through the carbon material in the carbon-Y zeolite composite to tightly combine with the core zeolite to form a composite zeolite.

[0024] In the method of the present application, the silicon source in step (2) is a soluble silicon salt, which can be sodium silicate, such as water glass.

[0025] In the method of the present application, the aluminum source in step (2) is a soluble aluminum salt, which can be at least one of aluminum nitrate, aluminum sulfate, and aluminum chloride.

[0026] In the method of the present application, the template agent in step (2) is tetraethylammonium bromide.

[0027] In the method of the present application, the inorganic base in step (2) is selected from at least one of sodium hydroxide and potassium hydroxide.

[0028] In the method of the present application, the molar ratio of the various materials in step (2) is 4-10 OH: 24-90 SiO2: Al2O3: 2500-5500 H2O: 3-20 M, preferably 5-9 OH: 25-80 SiO2: Al2O3: 3000-5000 H2O: 5-15 M. Among them, M represents the template agent, the inorganic base is calculated as OH, the silicon source is calculated as SiO2, and the aluminum source is calculated as Al2O3.

[0029] In the method of the present application, the mass ratio of the silicon source (calculated as SiO2) to the carbon-Y zeolite composite in step (2) is 7-22:100, preferably 10-20:100.

[0030] In the method of the present application, the crystallization reaction conditions in step (2) are as follows: the crystallization reaction temperature is 100-160℃, preferably the crystallization reaction temperature is 110-150℃, and the reaction time is 40-110h, preferably the reaction time is 50-100h.

[0031] In the method of the present application, the separation in step (2) can be performed by filtration, usually including multiple filtrations, typically 1-10 times.

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

[0033] In the method, the calcination in step (2) is high-temperature calcination at 400-600 DEG C for 1-10 h, and the calcination needs to be carried out in an oxygen-containing atmosphere (such as air or oxygen). The calcination can burn off the carbon material in the form of carbon dioxide, leaving only the composite zeolite.

[0034] The second aspect of the present application provides the Y zeolite-Beta zeolite composite structure zeolite synthesized by the above method.

[0035] In the present application, the thickness of the shell layer in the composite structure zeolite is 20-150 nm.

[0036] In the present application, the specific surface area of the composite structure zeolite is 300-800 m 2 / g.

[0037] In the composite structure zeolite of the present application, the Y zeolite is the core, located at the center of the whole structure, and the Beta zeolite is the shell layer, wrapped on the outer surface of the core zeolite. The core-shell structure is very stable and will not separate into two phases.

[0038] 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 can also be used for the adsorption and separation of gas and liquid.

[0039] The third aspect of the present application provides the application of the above composite structure zeolite in a catalyst for the catalytic hydrogenation of lignin to produce aromatic hydrocarbons.

[0040] In the present application, the application is to carry out conventional ammonium ion exchange on the composite structure zeolite, knead into a shape, impregnate and load a hydrogenation active metal component to prepare a catalyst. The hydrogenation active component is preferably a metal of Group VIB and / or a metal of Group VIII, wherein the metal of Group VIB is preferably molybdenum and / or tungsten, and the metal of Group VIII is preferably nickel and / or cobalt.

[0041] In the present application, preferably, based on the weight of the catalyst, the content of the metal of Group VIB in the form of oxide is 2%-10%, the content of the metal of Group VIII in the form of oxide is 2%-10%, and the content of the composite structure zeolite is 30%-80%.

[0042] Compared with the prior art, the present application has the following advantages:

[0043] The inventors have found that, when using the traditional hydrothermal synthesis method to synthesize Y zeolite-Beta composite zeolite with core-shell structure, Y zeolite and Beta zeolite often exist in an independent state instead of a stable core-shell structure, and the crystallinity of Y zeolite is low. One of the main reasons is that, during the hydrothermal synthesis process, a large amount of liquid water exists in the synthesis system, 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 Y zeolite will decrease. The inventors have further found that, by first preparing a carbon-Y 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-Y zeolite composite, and the core-shell structure of the Y zeolite-Beta zeolite composite structure zeolite obtained after crystallization is tight and not easy to separate, and the framework structures of Y zeolite and Beta zeolite are complete. The possible mechanism analysis is as follows: first, a carbon material with a specific mesoporous structure is formed on the surface of Y zeolite, and because a relatively low treatment temperature is used, various chemical groups of sugar substances are retained in the carbon material to improve the chemical activity of the carbon material. The carbon-Y zeolite composite is a solid composite material with a size of tens or even hundreds of microns, and the Y zeolite is wrapped by the carbon material. Because 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 and fill the space. When the crystallization reaction occurs, the formed zeolite shell layer can only combine with the core zeolite due to the limitation of the space, thereby forming a tight core-shell structure, so as to avoid the phenomenon that the shell layer and the core zeolite are separated from each other due to the severe impact of water during the crystallization reaction. In addition, the various chemical groups on the carbon material are beneficial to improve the crystallinity and catalytic performance of Beta zeolite.

[0044] The catalyst for preparing aromatic hydrocarbons by lignin hydroliquefaction and hydrogenation prepared from the composite structure zeolite has high activity and selectivity, and the content of aromatic hydrocarbons in the obtained product is obviously increased. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The scanning electron microscope photograph of sample A1 obtained in Example 1 is shown in the figure;

[0046] Figure 2 The XRD spectrum of sample A1 obtained in Example 1 is shown in the figure;

[0047] Figure 3 The XRD spectrum of sample DA1 obtained in Comparative Example 1 is shown in the figure;

[0048] Figure 4 The XRD spectrum of sample DA5 obtained in Comparative Example 5 is shown in the figure;

[0049] Figure 5 A scanning electron microscope photograph of sample DA1 obtained for Comparative Example 1 is shown in Figure 1. DETAILED DESCRIPTION

[0050] 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.

[0051] The pore structure of the composite structure zeolite is characterized by N2 adsorption-desorption, and is tested by a physical adsorption instrument of Micromeritics Corporation, USA. Before testing, the sample is treated in vacuum at 300 DEG C for more than 4 h. The total specific surface area and other parameters are calculated according to the BET formula.

[0052] The microcrystal morphology structure of the composite structure zeolite is characterized by a scanning electron microscope, and is tested by a JSM-6301F scanning electron microscope (equipped with Oxford EDS) of Japan Electronics Corporation, with a working voltage of 20 kV, a working distance of 15 mm, and a resolution of 1.5 nm.

[0053] The crystal phase structure and crystallinity of the composite structure zeolite are characterized by X-ray diffraction, and are tested by a D / max2500 X-ray diffractometer of Japan Rigaku, with a Cu target, a Kα radiation source, a graphite monochromator, a tube voltage of 40 kV, a tube current of 80 mA, a scanning range of 5 DEG to 40 DEG, a step length of 0.1 DEG, and a scanning speed of 1 DEG / min.

[0054] The thickness of the shell layer of the composite structure zeolite is characterized by high-resolution transmission electron microscopy, and is tested by a high-resolution transmission electron microscope of Japan JEOL Corporation, with an instrument model of JEM-2200FS field emission ultra-high-resolution transmission electron microscope, an acceleration voltage of 200 kV, and a point resolution of 0.19 nm.

[0055] Example 1

[0056] A clean container is taken, 100 g of Y zeolite (average particle size 1100 nm), 15000 g of distilled water, 20 g of iron oxide (average particle size 7 nm), and 200 g of sucrose are added and uniformly mixed; then the water is evaporated at 100 DEG C; then the sample is treated in nitrogen at 310 DEG C for 5 h; then the sample is mixed with 15000 g of 2 wt% hydrochloric acid for 20 min; then the obtained sample is filtered multiple times, and then is placed in an oven for drying at 110 DEG C for 12 h to obtain a carbon-Y zeolite composite.

[0057] Take a clean container, add 52 g water glass (silicon oxide mass content 20%), 220 g distilled water, mix evenly; add 72 g carbon-Y zeolite composite, mix evenly; add 0.96 g sodium hydroxide, mix evenly; add 8.5 g tetraethylammonium bromide, mix evenly; then add 1.2 g aluminum chloride, mix evenly. Then put into the reaction kettle and treat at 140°C for 80h; then filter the obtained sample several times, and then place it in an oven at 110°C for 12h, and finally calcine it at 500°C in air for 7h, and the obtained sample is numbered as A1.

[0058] The XRD spectrum of sample A1 is shown in Figure 1. Figure 2 As can be seen from the figure, the composite material contains two crystals, Y zeolite and Beta zeolite respectively. As can be seen from Table 1, both crystals have high crystallinity and high specific surface area.

[0059] The scanning electron microscope photo of sample A1 is shown in Figure 2. Figure 1 As can be seen from the figure, the sample belongs to core-shell structure, and the particle size of the composite material is about 1000 nm, which is irregular particle. The shell is rough, which is a rough Beta zeolite shell layer, and the shell thickness is about 100 nm. Figure 1 Example 2

[0060] Take a clean container, add 100 g Y zeolite (average particle size 1000 nm), 10000 g distilled water, 10 g iron oxide (average particle size 6 nm), 100 g glucose, mix evenly; then evaporate the water at 150°C; then treat at 300°C for 10h in nitrogen; then mix with 10000 g (1 wt% concentration of hydrochloric acid) for 10 min; then filter the obtained sample several times, and then place it in an oven at 110°C for 12h to dry, to obtain a carbon-Y zeolite composite.

[0061] Take a clean container, add 31 g water glass (silicon oxide mass content 20%), 200 g distilled water, mix evenly; add 62 g carbon-Y zeolite composite, mix evenly; add 0.83 g sodium hydroxide, mix evenly; add 4.4 g tetraethylammonium bromide, mix evenly; then add 1.1 g aluminum chloride, mix evenly. Then put into the reaction kettle and treat at 110°C for 100h; then filter the obtained sample several times, and then place it in an oven at 110°C for 12h to dry, and finally calcine it at 400°C in air for 10h, and the obtained sample is numbered as A2.

[0062] Sample A2 belongs to core-shell structure, and contains two crystals, Y zeolite and Beta zeolite respectively. Both crystals have high crystallinity and high specific surface area.

[0063] Example 3

[0064] ​

[0065] A clean container was taken and 100 g of Y zeolite (average particle size 970 nm), 20000 g of distilled water, 50 g of iron oxide (average particle size 9 nm), 500 g of sucrose were mixed well; then the water was evaporated at 150 °C; then it was treated in nitrogen at 350 °C for 2 h; then it was treated with 20000 g of 5 wt% concentration of hydrochloric acid for 30 min; then the obtained sample was filtered several times and then dried in an oven at 110 °C for 12 h to obtain carbon-Y zeolite composite.

[0066] A clean container was taken and 98 g of water glass (silicon oxide mass content 20%), 270 g of distilled water were mixed well; 98 g of carbon-Y zeolite composite was added and mixed well; 1.45 g of sodium hydroxide was added and mixed well; 13 g of tetraethylammonium bromide was added and mixed well; then 1.1 g of aluminum chloride was added and mixed well. Then it was loaded into a reaction kettle and treated at 150 °C for 50 h; then the obtained 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 1 h, and the obtained sample was numbered as A3.

[0067] Sample A3 belongs to a core-shell structure and contains two crystals, Y zeolite and Beta zeolite, both of which have high crystallinity and high specific surface area.

[0068] Example 4

[0069] A clean container was taken and 120 g of Y zeolite (average particle size 1300 nm), 15000 g of distilled water, 21 g of iron oxide (average particle size 7 nm), 220 g of glucose were mixed well; then the water was evaporated at 100 °C; then it was treated in nitrogen at 320 °C for 5 h; then it was treated with 15000 g of 3 wt% concentration of hydrochloric acid for 20 min; then the obtained sample was filtered several times and then dried in an oven at 110 °C for 12 h to obtain carbon-Y zeolite composite.

[0070] A clean container was taken and 57 g of water glass (silicon oxide mass content 20%), 220 g of distilled water were mixed well; 75 g of carbon-Y zeolite composite was added and mixed well; 0.91 g of sodium hydroxide was added and mixed well; 8.5 g of tetraethylammonium bromide was added and mixed well; then 1.2 g of aluminum chloride was added and mixed well. Then it was loaded into a reaction kettle and treated at 145 °C for 70 h; then the obtained sample was filtered several times and then dried in an oven at 110 °C for 12 h, and finally calcined in air at 500 °C for 7 h, and the obtained sample was numbered as A4.

[0071] Sample A4 belongs to a core-shell structure and contains two crystals, Y zeolite and Beta zeolite, both of which have high crystallinity and high specific surface area.

[0072] Example 5

[0073] A clean container was taken and 110 g of Y zeolite (average particle size of 1900 nm), 15000 g of distilled water, 19 g of iron oxide (average particle size of 6 nm), 210 g of sucrose were mixed uniformly; then the water was evaporated at 100 °C; then it was treated in nitrogen at 330 °C for 6.5 h; then it was treated with 13000 g (3.5 wt% concentration of hydrochloric acid) for 23 min; then the obtained sample was filtered multiple times and then dried in an oven at 110 °C for 12 h to obtain a carbon-Y zeolite composite.

[0074] A clean container was taken and 60 g of water glass (silicon oxide mass content of 20%), 220 g of distilled water were mixed uniformly; 80 g of carbon-Y zeolite composite was added and mixed uniformly; 1.1 g of sodium hydroxide was added and mixed uniformly; 8.5 g of tetraethylammonium bromide was added and mixed uniformly; then 1.8 g of aluminum nitrate nonahydrate was added and mixed uniformly. Then it was loaded into a reaction kettle and treated at 1350 °C for 80 h; then the obtained sample was filtered multiple times and then dried in an oven at 110 °C for 12 h, and finally calcined in air at 500 °C for 7 h, and the obtained sample was numbered as A5.

[0075] Sample A5 belongs to a core-shell structure and contains two crystals, Y zeolite and Beta zeolite, both of which have high crystallinity and high specific surface area.

[0076] Comparative Example 1

[0077] Compared with Example 1, the only difference is that the carbon-Y zeolite material is not prepared.

[0078] A clean container was taken and 52 g of water glass (silicon oxide mass content of 20%), 220 g of distilled water were mixed uniformly; 32 g of Y zeolite (average particle size of 1100 nm) was added and mixed uniformly; 0.96 g of sodium hydroxide was added and mixed uniformly; 8.5 g of tetraethylammonium bromide was added and mixed uniformly; then 1.2 g of aluminum chloride was added and mixed uniformly. Then it was loaded into a reaction kettle and treated at 140 °C for 80 h; then the obtained sample was filtered multiple times and then dried in an oven at 110 °C for 12 h, and finally calcined in air at 500 °C for 7 h, and the obtained sample was numbered as DA1.

[0079] The XRD spectrum of sample DA1 is shown in Figure 3 As can be seen from the figure, the composite material contains two crystals, Y zeolite and Beta zeolite, and as can be seen from Table 2, the Beta zeolite has very low crystallinity and slightly low specific surface area. The scanning electron microscope photograph of sample DA1 is shown in Figure 5 As can be seen from the figure, the composite material contains two crystals, Y zeolite and Beta zeolite, and as can be seen from Table 2, the Beta zeolite has very low crystallinity and slightly low specific surface area. The scanning electron microscope photograph of sample DA1 is shown in Figure 5It can be seen that the sample contains two kinds of zeolites, in which the larger crystal particles are Y zeolites with a size of about 1 micron and clear crystal edges and corners, and the smaller crystal particles are Beta zeolites with a size of about 3 to 5 hundred nanometers and round crystal edges and corners, 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.

[0080] Comparative Example 2

[0081] Compared with Example 1, the only difference is that no iron oxide is added in the preparation of the carbon-Y zeolite composite, and silica gel is used as the silicon source in the preparation of the core-shell zeolite.

[0082] A clean container was taken, 100 g of Y zeolite (average particle size 1100 nm), 15000 g of distilled water, and 200 g of sucrose were added and mixed uniformly; then the water was evaporated at 100°C; then treated with 15000 g (2 wt% concentration of hydrochloric acid) for 20 min under nitrogen at 310°C for 5 h; then the obtained sample was filtered several times, and then placed in an oven at 110°C for drying for 12 h to obtain a carbon-Y zeolite composite.

[0083] A clean container was taken, 10 g of silica gel (silicon oxide mass content 100%), 260 g of distilled water were added and mixed uniformly; 72 g of carbon-Y zeolite composite was added and mixed uniformly; 0.96 g of sodium hydroxide was added and mixed uniformly; 8.5 g of tetraethylammonium bromide was added and mixed uniformly; then 1.2 g of aluminum chloride was added and mixed uniformly. Then it was loaded into a reaction kettle and treated at 140°C for 80 h; then the obtained sample was filtered several times, and then placed in an oven at 110°C for drying for 12 h, and finally calcined in air at 500°C for 7 h, and the obtained sample was numbered as DA2.

[0084] Sample DA2 is in an independent state and contains two kinds of crystals, Y zeolite and Beta zeolite, both of which have low crystallinity and low specific surface area.

[0085] Comparative Example 3

[0086] Compared with Example 1, the only difference is that no iron oxide is added in the preparation of the carbon-Y zeolite composite, and aluminum hydroxide is used as the aluminum source in the preparation of the core-shell zeolite.

[0087] A clean container was taken and 100 g of Y zeolite (average particle size 1100 nm), 15000 g of distilled water, 200 g of sucrose were mixed well; then the water was evaporated at 100°C; then it was treated at 310°C under nitrogen for 5 h; then it was treated with 15000 g of 2 wt% hydrochloric acid for 20 min; then the sample was filtered several times and dried in an oven at 110°C for 12 h to obtain a carbon-Y zeolite composite.

[0088] A clean container was taken and 52 g of water glass (silicon oxide mass content 20%), 220 g of distilled water, 72 g of carbon-Y zeolite composite were mixed well; then 0.96 g of sodium hydroxide was added and mixed well; then 8.5 g of tetraethylammonium bromide was added and mixed well; then 0.7 g of aluminum hydroxide was added and mixed well. Then it was put into a reaction kettle and treated at 140°C for 80 h; then the sample was filtered several times and dried in an oven at 110°C for 12 h, and finally calcined in air at 500°C for 7 h, and the sample was numbered as DA3.

[0089] Sample DA3 is in an independent state and contains two crystals, Y zeolite and Beta zeolite, and the crystallinity of the two crystals is low, and the specific surface area is low.

[0090] Comparative Example 4

[0091] Compared with Example 1, the only difference is that no iron oxide is added when preparing the carbon-Y zeolite composite, and the raw materials are not added according to the feeding sequence of the application.

[0092] A clean container was taken and 100 g of Y zeolite (average particle size 1100 nm), 15000 g of distilled water, 200 g of sucrose were mixed well; then the water was evaporated at 100°C; then it was treated at 310°C under nitrogen for 5 h; then it was treated with 15000 g of 2 wt% hydrochloric acid for 20 min; then the sample was filtered several times and dried in an oven at 110°C for 12 h to obtain a carbon-Y zeolite composite.

[0093] A clean container was taken and 52 g of water glass (silicon oxide mass content 20%), 220 g of distilled water, 72 g of carbon-Y zeolite composite, 0.96 g of sodium hydroxide, 8.5 g of tetraethylammonium bromide, 1.2 g of aluminum chloride were added and mixed well. Then it was put into a reaction kettle and treated at 140°C for 80 h; then the sample was filtered several times and dried in an oven at 110°C for 12 h, and finally calcined in air at 500°C for 7 h, and the sample was numbered as DA4.

[0094] Sample DA4 is in an independent state and contains two crystals, Y zeolite and Beta zeolite, and the crystallinity of the two crystals is low, and the specific surface area is low.

[0095] Comparative Example 5

[0096] Compared with Example 1, the only difference is that the processing temperature during the preparation of the carbon-Y zeolite composite is a conventional high temperature.

[0097] Take a clean container, add 100g of Y zeolite (1100nm), 15000g of distilled water, 20g of iron oxide (average particle size 7nm), and 200g of sucrose and mix well; then evaporate the water at 100℃; then treat in nitrogen at 900℃ for 5h; then mix with 15000g (2wt% hydrochloric acid) and treat for 20min; then filter the obtained sample several times, and then place it in an oven to dry at 110℃ for 12h to obtain carbon-Y zeolite composite.

[0098] Take a clean container, add 52g of water glass (20% silica by mass) and 220g of distilled water, and mix well; add 72g of carbon-Y zeolite composite and mix well; then add 0.96g of sodium hydroxide and mix well; then add 8.5g of tetraethylammonium bromide and mix well; finally add 1.2g of aluminum chloride and mix well. Then, place the mixture in a reaction vessel and treat at 140℃ for 80h; filter the resulting sample several times, then dry it in an oven at 110℃ for 12h, and finally calcine it in air at 500℃ for 7h. The resulting sample is designated DA5.

[0099] Sample DA5 has a core-shell structure and contains two types of crystals: Y zeolite and Beta zeolite. However, Beta zeolite has lost too much crystallinity and has a low specific surface area.

[0100] Depend on Figure 4 It can be seen that sample DA5 contains two types of crystals, namely Y zeolite and Beta zeolite.

[0101] Comparative Example 6

[0102] The only difference from Example 1 is that iron oxide was not added when preparing the carbon-Y zeolite composite.

[0103] Take a clean container, add 100g of Y zeolite (average particle size 1100nm), 15000g of distilled water, and 200g of sucrose and mix well; then evaporate the water at 100℃; then treat in nitrogen at 310℃ for 5h; then mix with 15000g (2wt% hydrochloric acid) and treat for 20min; then filter the obtained sample several times, and then place it in an oven to dry at 110℃ for 12h to obtain carbon-Y zeolite composite.

[0104] A clean container was taken and 52 g of water glass (silicon oxide mass content 20%) was added, 220 g of distilled water was added, and mixed evenly; 72 g of carbon-Y zeolite composite was added and mixed evenly; 0.96 g of sodium hydroxide was added and mixed evenly; 8.5 g of tetraethylammonium bromide was added and mixed evenly; then 1.2 g of aluminum chloride was added and mixed evenly. After that, it was loaded into a reaction kettle and treated at 140°C for 80h; then the obtained sample was filtered multiple times, and then placed in an oven at 110°C for drying for 12h, and finally calcined at 500°C in air for 7h, and the obtained sample was numbered as DA6.

[0105] The sample DA6 belongs to an independent state, and contains two crystals, Y zeolite and Beta zeolite, and the crystallinity of the two crystals is low, and the specific surface area is low.

[0106] Table 1: Physicochemical properties of samples obtained in each example

[0107]

[0108] Note: In the present application, the crystallinity of Y zeolite and Beta zeolite in the sample of Example 1 is 100%, the relative crystallinity of Y zeolite of all samples is obtained by comparing the crystallinity of Y zeolite of the sample with the crystallinity of Y zeolite of the sample of Example 1, and the relative crystallinity of Beta zeolite of all samples is obtained by comparing the crystallinity of Beta zeolite of the sample with the crystallinity of Beta zeolite of the sample of Example 1; The shell thickness given in Table 1 is about the thickness.

[0109] Table 2: Physicochemical properties of samples obtained in each comparative example

[0110]

[0111] Note: In the present application, the crystallinity of Y zeolite and Beta zeolite in the sample of Example 1 is 100%, the relative crystallinity of Y zeolite of all samples is obtained by comparing the crystallinity of Y zeolite of the sample with the crystallinity of Y zeolite of the sample of Example 1, and the relative crystallinity of Beta zeolite of all samples is obtained by comparing the crystallinity of Beta zeolite of the sample with the crystallinity of Beta zeolite of the sample of Example 1.

[0112] Application example

[0113] The catalytic performance of the material was investigated by using lignin hydrogenation liquefaction.

[0114] The materials of Example 1-5, Comparative Example 1, Comparative Example 5 and Comparative Example 6 were prepared into catalysts Cat1-Cat5, DCat1, DCat5 and DCat6 respectively according to conventional method. The catalyst preparation process included conventional ammonium ion exchange, kneading into shape, isometric impregnation loading metal nickel, and the nickel metal content in the finally prepared catalyst was 5wt%.

[0115] The performance of the catalysts was evaluated in an autoclave, the raw material was 150g of lignin, 2g of catalyst, 0.5g of carbon disulfide, 650mL of tetralin, the hydrogen pressure was 5MPa, the reaction temperature was 370℃, the reaction time was 30min, and the content of aromatic hydrocarbon in the liquid product was used as the catalytic performance index. The calculation method of the content of aromatic hydrocarbon was the mass percentage of aromatic hydrocarbon in the product in the reaction product, and the evaluation results are shown in Table 2.

[0116] Table 2 Evaluation results

[0117]

[0118]

Claims

1. A method for synthesizing a Y zeolite-Beta zeolite composite structure zeolite, the composite structure zeolite being a core-shell structure, wherein Y zeolite is the core and Beta zeolite is the shell layer, the method comprising the following steps: (1) mixing Y zeolite, water, nano iron oxide particles and a saccharide, evaporating the water, then heating under an inert atmosphere, followed by acid treatment, and then separating and drying to obtain a carbon-Y zeolite composite; (2) mixing water and a silicon source, then sequentially adding the carbon-Y zeolite composite, an inorganic base, a template agent and an aluminum source, mixing uniformly, crystallizing, and then separating, drying and calcining to obtain the composite structure zeolite; wherein in step (1), the saccharide is at least one of sucrose, glucose, fructose, maltose and lactose; in step (1), the mass ratio of Y zeolite to the saccharide is 1:0.8-6.0, the mass ratio of Y zeolite to water is 1:80-210, and the mass ratio of Y zeolite to iron oxide is 1:0.08-0.60; in step (1), the heating temperature under the inert atmosphere is 300-350℃, and the treatment time is 2-10h; in step (1), 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 (1), the mass ratio of Y zeolite to the acid solution is 1:80-210, and the acid treatment is mixing the heated solid with the acid solution and treating at 10-40℃ for 5-35min; in step (2), the silicon source is water glass, the aluminum source is at least one of aluminum nitrate, aluminum sulfate and aluminum chloride, the template agent is tetraethylammonium bromide, and the inorganic base is at least one of sodium hydroxide and potassium hydroxide; in step (2), the molar ratio of the various materials is 4-10OH:24-90SiO2:Al2O3:2500-5500H2O:3-20M, wherein M represents the template agent, the inorganic base is calculated as OH, the silicon source is calculated as SiO2, and the aluminum source is calculated as Al2O3; in step (2), the mass ratio of the silicon source calculated as SiO2 to the carbon-Y zeolite composite is 7-22:100; in step (2), the crystallization reaction conditions are as follows: the crystallization reaction temperature is 100-160℃, and the reaction time is 40-110h; in step (2), the drying temperature is 100-150℃, the drying time is 1-20h, the calcination is carried out at a high temperature of 400-600℃ for 1-10h, and the calcination is carried out in an oxygen-containing atmosphere.

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

3. The method of synthesis of claim 1, wherein, in step (1), the particle size of the Y zeolite is 500-3500nm, and / or the particle size of the nano iron oxide particles is 2-15nm.

4. The method of synthesis of claim 3, wherein, in step (1), the particle size of the Y zeolite is 600-3000nm, and / or the particle size of the nano iron oxide particles is 5-10nm.

5. The method of synthesis of claim 1, wherein, The mass ratio of the Y zeolite to the sugar in step (1) is 1:1.0-5.0; and / or, the mass ratio of the Y zeolite to water is 1:100-200; and / or, the mass ratio of the Y zeolite to the iron oxide is 1:0.10-0.

50.

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

7. The method of synthesis of claim 6, wherein, The temperature for evaporating the water in step (1) is 100-150℃.

8. The method of synthesis of claim 1, wherein, The inert atmosphere in step (1) is selected from nitrogen.

9. The method of synthesis of claim 1, wherein, The mass concentration of the acid in step (1) is 1.0%-5.0%.

10. The method of synthesis of claim 1, wherein, The mass ratio of the Y zeolite to the acid solution in step (1) is 1:100-200; and the acid treatment time is 10-30 min.

11. The method of synthesis of claim 1, wherein, The drying temperature in step (1) is 100-150℃, and the drying time is 1-20 h.

12. The method of synthesis of claim 1, wherein, The molar ratio of the various materials in step (2) is 5-9 OH:25-80 SiO2:Al2O3:3000-5000 H2O:5-15 M; wherein M represents a template, the inorganic base is calculated as OH, the silicon source is calculated as SiO2, and the aluminum source is calculated as Al2O3.

13. The method of synthesis of claim 1, wherein, The mass ratio of the silicon source calculated as SiO2 to the carbon-Y zeolite composite in step (2) is 10-20:

100.

14. The method of synthesis of claim 1, wherein, The crystallization reaction conditions in step (2) are as follows: the crystallization reaction temperature is 110-150℃, and the reaction time is 50-100 h.

15. The Y zeolite-Beta zeolite composite structure zeolite synthesized by any of the synthesis methods in claims 1-14.

16. The composite structure zeolite of claim 15, wherein, The thickness of the shell layer of the composite structure zeolite is 20-150 nm.

17. The composite structure zeolite of claim 15, wherein, The specific surface area of the composite structure zeolite is 300-800 m 2 / g.

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