Hierarchical porous high-silica Y zeolite synthesized in-situ from kaolin microspheres and its preparation method

Abstract

The present invention provides a hierarchical pore high-silica Y-type molecular sieve synthesized in-situ from kaolin microspheres and a preparation method thereof. The preparation method includes: mixing kaolin, a dispersant, a binder, seeds of the Y-type molecular sieve and water, forming the mixture into kaolin microspheres through molding, and then calcining the kaolin microspheres to obtain activated kaolin microspheres; mixing at least the activated kaolin microspheres, a silicon source treated with a weak acid, transition metal ions and a hydroxyl radical initiator to obtain a gel system, subjecting the gel system to crystallization, and then drying at least to obtain the hierarchical pore high-silica Y-type molecular sieve. The hierarchical pore high-silica Y-type molecular sieve provided by the present invention is prepared by this preparation method. The present invention uses kaolin as a raw material, and through the synergistic effect of a silicon source treated with a weak acid, transition metal ions and a hydroxyl radical initiator, a hierarchical pore high-silica Y-type molecular sieve is obtained by in-situ crystallization without using an organic template agent.

Description

Technical Field

[0001] The present invention relates to a hierarchical porous high-silica Y zeolite synthesized in-situ from kaolin microspheres and a preparation method thereof, belonging to the technical field of zeolites. Background Art

[0002] Due to advantages such as a large specific surface area and strong acidity, Y zeolites are widely used in fields such as heavy oil catalytic cracking and adsorption separation. However, their low silica-alumina ratio and inherent microporous channels greatly limit their industrial applications. Therefore, increasing the silica-alumina ratio of Y zeolites and introducing a hierarchical pore structure, increasing the acid strength and reasonably reducing the acid center density to improve the reaction performance of zeolite catalysts in catalytic reactions have become the focus of attention of researchers.

[0003] The fluid catalytic cracking (FCC) catalyst prepared by in-situ crystallization of kaolin uses kaolin as the basic raw material, forms kaolin microspheres through beating and spray drying, undergoes calcination activation, in-situ crystallization to synthesize a zeolite catalyst precursor, and then obtains a Y-type catalytic cracking catalyst through operations such as ion exchange and water washing. The FCC catalyst prepared by this method has high thermal stability and catalytic activity. Therefore, preparing a high-silica hierarchical pore Y zeolite catalyst by the kaolin in-situ crystallization method has important theoretical significance and research value.

[0004] CN107973312A discloses a mesoporous-rich Y zeolite and a preparation method thereof. This method performs two ammonium exchanges, hydrothermal treatment, acid treatment, and alkali treatment on NaY zeolite to obtain a mesoporous-rich Y zeolite. This method uses a large amount of acid and alkali for post-treatment, and has many steps, which is not conducive to its industrial development.

[0005] CN106927479A discloses a method for preparing a mesoporous Y zeolite. This method mixes a silicon source, an aluminum source, and water, ages to obtain a directing agent; then mixes the silicon source and the directing agent, then adds the aluminum source and water, and crystallizes for 15-20 h to obtain a crystallization solution; polyacrylamide is added to the crystallization solution, and after crystallization, the product is recovered. The pore size of this product is concentrated in the range of 1.5-3 nm. However, this method uses the organic matter polyacrylamide as a template agent. The use of organic matter has a certain pollution to the environment, and the crystallization process is cumbersome and time-consuming, which is not conducive to large-scale production applications.

[0006] Valtchev et al. (Angewandte Chemie International Edition, 2016, 55: 15049 - 15052) used NH4F as a mineralizing agent to break the framework Si - O and Al - O bonds in zeolites, generating a rectangular multi - level pore - embedded structure. HF and HF - 2 produced by the hydrolysis and secondary hydrolysis of NH4F extract silicon and aluminum atoms from the framework at the same rate. The zeolite framework is sensitive to F - between the interconnected crystals. With the extension of the etching time, these structures transform into highly interconnected mesopores. However, fluoride ions greatly limit their large - scale production.

[0007] Zhao et al. (Catalysis Communications, 2016, 73: 98 - 102) used the P123 block copolymer as a template and synthesized mesoporous Y zeolite by hydrothermal synthesis. When evaluating the micro - activity of the catalyst, the results showed that the Meso - CAT - 3 catalyst had a higher micro - activity and the lowest coke yield. This is attributed to the fact that the mesoporous structure can improve the mass transfer of macromolecules. However, this method requires the use of P123 as a template, which is not environmentally friendly.

[0008] Choi et al. (Nature Materials, 2006, 5(9): 718 - 723) combined traditional surfactants with organosilanes to obtain 3 - (trimethoxysilyl) propyl hexadecyl dimethyl ammonium chloride (TPHAC). After hydrolysis, the methoxy groups are stably connected to silicon - aluminum species by covalent bonds, effectively improving the occurrence of phase separation. Adjusting the length of the hydrophobic alkyl chain can correspondingly change the size of the mesoporous channels.

[0009] CN1204228C discloses a preparation method of a high - activity fluid catalytic cracking catalyst. This method uses kaolin as the main raw material and prepares a high - activity FCC catalyst through in - situ crystallization technology. By spray - drying and forming kaolin, solid seeds, additives, organic dispersants, and binders into microspheres, and then undergoing calcination activation and crystallization reaction with sodium silicate, sodium hydroxide, etc., a crystallized microsphere with a NaY zeolite content of 20 - 70% and a zeolite silicon - aluminum ratio of 4.0 - 6.0 is obtained. The synthesized catalyst has strong heavy - metal resistance, high catalytic activity, and low cost.

[0010] CN1429882A discloses an in - situ crystallization cracking catalyst and its preparation method. This method mixes calcined kaolin microspheres with water glass, sodium hydroxide, and water glass, and obtains a crystallized product under high - temperature crystallization with an additional aluminum source. The crystallized product is filtered, washed, and ion - exchanged to obtain a high - silicon - aluminum - ratio and high - crystallinity Y - type zeolite cracking catalyst, which shows excellent performance in heavy - oil catalytic cracking.

[0011] CN1597850A discloses a catalytic cracking catalyst for reducing the sulfur content of gasoline and its preparation method. This method is obtained by in-situ crystallization of kaolin to synthesize Y-type molecular sieve and through ion exchange or / and rare earth ion exchange. The prepared molecular sieve catalyst has a silica-alumina ratio of more than 4.5. The molecular sieve of this catalyst has good dispersion and excellent hydrothermal stability. It not only has good catalytic cracking performance but also has excellent function of reducing the sulfur content of gasoline.

[0012] CN101619228B discloses a method for rapidly in-situ synthesizing a catalytic cracking catalyst. This method makes a slurry of kaolin, binder and water, spray-dries and shapes it into microspheres, activates it through high-temperature calcination, mixes and hydrothermally crystallizes it in an alkaline solution, and obtains an in-situ crystallization product through filtration and washing. By adding an external aluminum source during the in-situ synthesis of the catalytic cracking catalyst, this invention greatly improves the crystallization rate, shortens the crystallization time, improves the synthesis efficiency, and reduces the synthesis cost of the molecular sieve.

[0013] Guo et al. (Microporous and Mesoporous Materials. 2021, 326, 111340) found that potassium tartrate has a more obvious effect than potassium hydroxide and sodium hydroxide in regulating the structure of lignin-based porous carbon materials. At the same time, the activation mechanism of potassium tartrate on alkali lignin may be different from that of potassium hydroxide and sodium hydroxide. When the activation temperature is 500 - 600 °C, the organic part of the carbon precursor is degraded, the inorganic part of potassium tartrate begins to form potassium carbonate, and the organic part of potassium tartrate (tartrate) can also be used as a carbon source to prepare porous materials.

[0014] The above-mentioned preparation method of Y-type molecular sieve prepares a Y-type molecular sieve catalyst through in-situ crystallization of kaolin microspheres and shows excellent performance in the field of heavy oil catalytic cracking. However, the synthesized Y-type molecular sieve has a low silica-alumina ratio and no mesopores in the molecular sieve, which greatly affects its application in the catalytic field. Therefore, developing a method for in-situ crystallization of kaolin microspheres to synthesize hierarchical pore high-silica Y-type molecular sieve has become one of the urgent problems to be solved in this field. Summary of the Invention

[0015] To solve the above technical problems, the purpose of the present invention is to provide a hierarchical pore high-silica Y-type molecular sieve synthesized in-situ from kaolin microspheres and its preparation method. The present invention uses kaolin as a raw material to in-situ crystallize to obtain a hierarchical pore high-silica Y-type molecular sieve.

[0016] To achieve the above purpose, the present invention provides a preparation method of a hierarchical pore high-silica Y-type molecular sieve synthesized in-situ from kaolin microspheres, which includes the following steps:

[0017] (1) Mix kaolin, a dispersant, a binder, seeds of Y-type zeolite, and water to obtain a slurry; form the slurry into kaolin microspheres, and then calcine the kaolin microspheres to obtain activated kaolin microspheres;

[0018] (2) Mix at least the activated kaolin microspheres, a silicon source treated with a weak acid, transition metal ions, and a hydroxyl radical initiator to obtain a gel system; subject the gel system to crystallization and then at least drying to obtain the hierarchical porous high-silica Y-type zeolite.

[0019] In the above preparation method, preferably, in step (1), the kaolin includes soft kaolin, etc.

[0020] In the above preparation method, preferably, in step (1), the particle size of the kaolin is 3 - 10 μm.

[0021] In the above preparation method, preferably, in step (1), based on the total mass of the kaolin being 100%, the alumina content is 40% - 45%, the silica content is 52.8% - 58%, the iron oxide content is below 1.7%, and the sum of the sodium oxide and potassium oxide contents is below 0.5%.

[0022] In the above preparation method, preferably, in step (1), the mixing mass ratio of the dispersant to the kaolin is (1 - 3):100.

[0023] In the above preparation method, preferably, in step (1), the dispersant includes sodium polyacrylate, etc.

[0024] In the above preparation method, preferably, in step (1), the mixing mass ratio of the binder to the kaolin is 0.16 - 0.33.

[0025] In the above preparation method, preferably, in step (1), the binder includes one or a combination of several of sodium silicate, water glass, and silica sol, etc.

[0026] In the above preparation method, preferably, in step (1), the mixing mass ratio of the seeds of Y-type zeolite to the kaolin is (1 - 20):100. More preferably, the mixing mass ratio of the seeds of Y-type zeolite to the kaolin is (1 - 15):100.

[0027] In the above preparation method, preferably, in step (1), the seed crystal of the Y-type molecular sieve is a solid seed crystal of the Y-type molecular sieve, including one or a combination of several of NaY molecular sieve, HY molecular sieve, and USY molecular sieve; the crystal grain size of the seed crystal of the Y-type molecular sieve is 0.5 - 1.5 μm, the relative crystallinity is 95% - 99%, and the silica-alumina ratio is 3.5 - 5.5. The seed crystal is a pure-phase Y-type molecular sieve without other miscellaneous crystals.

[0028] In the above preparation method, preferably, in step (1), the solid content of the slurry is 30 - 55%.

[0029] In the above preparation method, preferably, in step (1), the particle size of the kaolin microspheres obtained by forming is 20 - 110 μm.

[0030] In the above preparation method, preferably, in step (1), the forming includes spray drying forming. The spray drying forming can be carried out in a spray dryer, and its operating conditions are preferably: the hot air inlet temperature is controlled at 115 - 125 °C, the sample injection flow rate is 15 - 25%, and the atomizing air flow rate is 450 - 550 L / h.

[0031] In the above preparation method, preferably, in step (1), the calcination temperature of the kaolin microspheres is 750 - 1000 °C, and the calcination time is 1 - 5 h.

[0032] In the above preparation method, preferably, in step (2), in addition to mixing the activated kaolin microspheres, the weak acid-treated silicon source, the transition metal ions, and the hydroxyl radical initiator, an alkali source and / or water are also included. More preferably, sodium hydroxide, ammonium hydroxide, etc. can be used as the alkali source to adjust the pH value of the gel system.

[0033] In the above preparation method, preferably, in step (2), the pH value of the gel system is 10 - 14.

[0034] In the above preparation method, preferably, in step (2), the gel system is prepared by the following method: mixing the activated kaolin microspheres, the weak acid-treated silicon source, the alkali source that can be optionally added or not added, and the water that can be optionally added or not added to obtain a first mixture; mixing the transition metal ions and the hydroxyl radical initiator to obtain a first mixed solution; mixing the first mixture with the first mixed solution to obtain the gel system.

[0035] In the above preparation method, preferably, in step (2), the molar ratio of Na2O:Al2O3:SiO2:H2O in the first mixture is (1 - 30):1:(1 - 40):(200 - 800).

[0036] In the above preparation method, those skilled in the art should understand that if the above sodium hydroxide and / or ammonium hydroxide are used in the form of a solution as the base source, and if the molar ratios of the components in the first mixture and the pH value of the gel system meet the above conditions, water does not need to be added additionally during the preparation of the first mixture; if sodium hydroxide and / or ammonium hydroxide are not used in the form of a solution as the base source, in order to fully mix the activated kaolin microspheres and the silicon source treated with the weak acid and to make the molar ratios of the components in the first mixture meet the above conditions, water needs to be added during the preparation of the first mixture.

[0037] In the above preparation method, preferably, in step (2), the silicon source includes one or a combination of several of water glass, sodium silicate, tetraethyl orthosilicate, etc.

[0038] In the above preparation method, preferably, in step (2), the weak acid includes one or a combination of several of tartaric acid, 2-hydroxybutanedioic acid, citric acid, etc.

[0039] In the above preparation method, preferably, in step (2), the silicon source treated with the weak acid is obtained by the following method: mixing the silicon source and the weak acid evenly at a mass ratio of 1:(1.5 - 3), and then standing for 2 - 4 h to obtain the silicon source treated with the weak acid. More preferably, the temperature for mixing and standing is 35 - 70 °C. The processes of mixing and standing can both be carried out in a water bath.

[0040] In the above preparation method, preferably, in step (2), the addition amount of the transition metal ions is 1% - 5% of the molar amount of Al2O3 in the gel system. Among them, the molar amount of Al2O3 in the gel system is the same as the molar amount of Al2O3 in the first mixture.

[0041] In the above preparation method, preferably, in step (2), the addition amount of the hydroxyl radical initiator is 1% - 7% of the molar amount of Al2O3 in the gel system. Among them, the molar amount of Al2O3 in the gel system is the same as the molar amount of Al2O3 in the first mixture.

[0042] In the above preparation method, preferably, in step (2), the transition metal ions include Fe 3+ , Cu 2+ , Mn 6 + , Mn 7+ and Ni 2+A combination of one or more of the like. The transition metal ions can be mixed with other raw materials in the form of a transition metal ion salt solution. More preferably, the transition metal ion salt solution includes a combination of one or more of ferric chloride, copper chloride, nickel chloride, potassium manganate, potassium permanganate, and the like.

[0043] In the above preparation method, preferably, in step (2), the hydroxyl radical initiator includes a combination of one or more of sodium persulfate, potassium persulfate, and hydrogen peroxide, and the like.

[0044] In the above preparation method, preferably, in step (2), the temperature for mixing the activated kaolin microspheres, the silicon source treated with a weak acid, the transition metal ions, and the hydroxyl radical initiator is 25 - 80 °C. More specifically, the temperature for mixing the first mixture with the first mixed solution is 25 - 80 °C. More preferably, the mixing is carried out under stirring conditions, and the stirring time is 2 - 5 h. The stirring speed is preferably 150 - 350 r / min.

[0045] In the above preparation method, preferably, in step (2), the crystallization temperature is 90 - 120 °C, and the time is 12 - 48 h. More preferably, the crystallization temperature is 95 - 110 °C, and the time is 12 - 24 h. The crystallization can be static crystallization or dynamic crystallization, and dynamic crystallization is, for example, rotary dynamic crystallization or stirring dynamic crystallization. More preferably, the crystallization is static crystallization.

[0046] In the above preparation method, in step (2), before drying the crystallized product, conventional steps such as filtration and washing can also be carried out. The present invention does not specifically limit it, and it can be conventionally adjusted by those skilled in the art.

[0047] In the above preparation method, preferably, in step (2), the drying temperature is 60 - 90 °C, and the time is 12 - 18 h.

[0048] The second aspect of the present invention provides a hierarchical pore high-silica Y-type zeolite synthesized in-situ from kaolin microspheres, which is prepared by the preparation method of the hierarchical pore high-silica Y-type zeolite synthesized in-situ from kaolin microspheres as described above.

[0049] According to the specific embodiments of the present invention, preferably, the silica-to-alumina ratio of the hierarchical pore high-silica Y-type zeolite synthesized in-situ from kaolin microspheres is 6.0 or more. More preferably, the silica-to-alumina ratio of the hierarchical pore high-silica Y-type zeolite synthesized in-situ from kaolin microspheres is 6.0 - 6.8.

[0050] According to the specific embodiments of the present invention, preferably, the crystal grain size of the hierarchical pore high-silica Y-type zeolite synthesized in-situ from kaolin microspheres is 0.6 - 1.2 μm.

[0051] According to a specific embodiment of the present invention, preferably, the hierarchically porous high-silica Y zeolite synthesized in-situ on kaolin microspheres has a microporous structure and a mesoporous structure, and the specific surface area of the hierarchically porous high-silica Y zeolite is 700-790 m 2 ·g -1 , the micropore volume is 0.15-0.30 cm 3 ·g -1 , and the mesopore volume is 0.25-0.40 cm 3 ·g -1 .

[0052] According to a specific embodiment of the present invention, preferably, the relative crystallinity of the hierarchically porous high-silica Y zeolite synthesized in-situ on kaolin microspheres is above 85%.

[0053] According to a specific embodiment of the present invention, preferably, the hierarchically porous high-silica Y zeolite synthesized in-situ on kaolin microspheres is hierarchically porous high-silica Y zeolite microspheres. Based on the total mass of the hierarchically porous high-silica Y zeolite microspheres being 100%, the content of the hierarchically porous high-silica Y zeolite therein is 40-65%.

[0054] According to a specific embodiment of the present invention, preferably, the hierarchically porous high-silica Y zeolite synthesized in-situ on kaolin microspheres is hierarchically porous high-silica Y zeolite microspheres, and the particle size of the hierarchically porous high-silica Y zeolite microspheres is 15-100 μm.

[0055] The present invention provides a hierarchically porous high-silica Y zeolite synthesized in-situ on kaolin microspheres and a preparation method thereof. The preparation method of the present invention pre-introduces solid seeds of Y zeolite into kaolin microspheres, realizing the in-situ growth of Y zeolite on kaolin microspheres; and uses transition metal ions to promote the generation of a large amount of hydroxyl radicals, accelerate the formation of Si-O-Si bonds, and promote the dissolution of active silicon in kaolin microspheres, so that the silicon-aluminum ratio in the system is increased, thereby increasing the silicon-aluminum ratio of Y zeolite and obtaining a high-silica Y zeolite; at the same time, the present invention uses a weak acid to treat the silicon source, and the treated silicon source will form highly polymerized silicate ions. After the weak acid dissolves in the system, it combines with sodium ions to form sodium salts, which can enter between the molecular sieve lattices during the crystallization process and react to release carbon dioxide during calcination, generating mesopores. Therefore, the present invention in-situ crystallizes and synthesizes hierarchically porous high-silica Y zeolite on the surface of kaolin microspheres with the assistance of weak acid, transition metal ions and hydroxyl radical initiators, improves its catalytic activity in the catalytic field, and thus broadens the scope of industrial application of in-situ crystallization type molecular sieve catalysts.

[0056] In the conventional preparation method of Y-type molecular sieve, due to the slow dissolution rate of the active silicon in the kaolin microspheres in the synthesis system and the low silicon-aluminum ratio of the system itself, it is easy to obtain a low-silica Y-type molecular sieve. Generally, the silicon-aluminum ratio of the synthesized Y-type molecular sieve is 3.5 - 5.5. However, in the present invention, natural kaolin ore is used as the raw material, and under the synergistic action of a silicon source treated with weak acid, transition metal ions, and a hydroxyl radical initiator, in-situ crystallization synthesis of hierarchical pore high-silica Y-type molecular sieve from kaolin microspheres is achieved. The preparation method of the present invention is simple, avoids the addition of organic template agents, is environmentally friendly and reduces costs, and has broad application prospects, which is of great significance for promoting the development of material synthesis and catalyst performance and other aspects. Description of the Drawings

[0057] Figure 1 The characteristic X-ray diffraction pattern of the hierarchical pore high-silica Y-type molecular sieve microspheres provided in Example 2. Detailed Embodiments

[0058] In order to have a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solutions of the present invention will be described in detail below, but it should not be construed as a limitation on the implementable scope of the present invention.

[0059] According to the specific embodiments of the present invention, preferably, the method for synthesizing hierarchical pore high-silica Y-type molecular sieve from kaolin microspheres in-situ crystallization of the present invention includes the following steps:

[0060] (1) Mix kaolin, a dispersant, a binder, solid seeds of Y-type molecular sieve, and water to obtain a slurry;

[0061] Among them, the kaolin includes soft kaolin, etc.; the particle size of the kaolin is 3 - 10 μm; based on the total mass of the kaolin being 100%, the alumina content therein is 40% - 45%, the silica content is 52.8% - 58%, the iron oxide content is below 1.7%, and the sum of the sodium oxide and potassium oxide contents is below 0.5%; the mixing mass ratio of the dispersant to the kaolin is (1 - 3):100; the dispersant includes sodium polyacrylate; the mixing mass ratio of the binder to the kaolin is 0.16 - 0.33; the binder includes one or a combination of several of sodium silicate, water glass, and silica sol; the mixing mass ratio of the seed crystal of the Y-type molecular sieve to the kaolin is (1 - 20):100 (more preferably (1 - 15):100); the solid seed crystal of the Y-type molecular sieve includes one or a combination of several of NaY molecular sieve, HY molecular sieve, and USY molecular sieve; the crystal grain size of the solid seed crystal of the Y-type molecular sieve is 0.5 - 1.5 μm, the relative crystallinity is 95% - 99%, and the silica-alumina ratio is 3.5 - 5.5; the solid seed crystal of the Y-type molecular sieve is a pure-phase Y-type molecular sieve without other miscellaneous crystals; the solid content of the slurry is 30 - 55%;

[0062] The slurry is spray-dried and formed into kaolin microspheres with a particle size of 20 - 110 μm, and then the kaolin microspheres are calcined at 750 - 1000 °C for 1 - 5 h to obtain activated kaolin microspheres;

[0063] (2) Mix the activated kaolin microspheres, the silicon source treated with weak acid, the optional alkali source that can be added or not added, and the optional water that can be added or not added to obtain a first mixture; mix the transition metal ions and the hydroxyl radical initiator evenly (which can be carried out at room temperature) to obtain a first mixed solution; mix and stir the first mixture and the first mixed solution at 25 - 80 °C for 2 - 5 h (the stirring speed is more preferably 150 - 350 r / min) to obtain a gel system;

[0064] wherein the molar ratio of Na2O:Al2O3:SiO2:H2O in the first mixture is (1-30):1:(1-40):(200-800); the pH value of the gel system is 10-14; the silicon source comprises one or more of water glass, sodium silicate and tetraethyl orthosilicate; the weak acid comprises one or more of tartaric acid, 2-hydroxysuccinic acid and citric acid; the weakly acid-treated silicon source is obtained by the following method: the silicon source and the weak acid are mixed uniformly at a mass ratio of 1:(1.5-3), and the mixture is allowed to stand for 2-4 hours to obtain the weakly acid-treated silicon source; more preferably, the mixing and standing temperature is 35-70°C; the alkali source comprises sodium hydroxide and / or ammonium hydroxide; the amount of the transition metal ion added is 1%-5% of the molar amount of Al2O3 in the gel system; the amount of the hydroxyl radical initiator added is 1%-7% of the molar amount of Al2O3 in the gel system; the transition metal ion comprises Fe 3+ , Cu 2+ , Mn 6+ , Mn 7+ and Ni 2+ The hydroxyl radical initiator includes one or a combination of sodium persulfate, potassium persulfate and hydrogen peroxide;

[0065] The gel system is transferred to a polytetrafluoroethylene reactor, and statically crystallized at 90-120° C. for 12-48 hours (more preferably statically crystallized at 95-110° C. for 12-24 hours), and then filtered and washed, and dried at 60-90° C. for 12-18 hours to obtain the multi-level pore high-silicon Y-type molecular sieve.

[0066] The multi-level pore high-silicon Y-type molecular sieve is a multi-level pore high-silicon Y-type molecular sieve microsphere, and the particle size of the multi-level pore high-silicon Y-type molecular sieve microsphere is 15-100 μm; based on the total mass of the multi-level pore high-silicon Y-type molecular sieve microsphere as 100%, the content of the multi-level pore high-silicon Y-type molecular sieve is 40-65%; the silicon-aluminum ratio of the multi-level pore high-silicon Y-type molecular sieve is above 6.0, and more preferably 6.0-6.8; the specific surface area of the multi-level pore high-silicon Y-type molecular sieve is 737m 2 ·g -1 , the micropore volume is 0.20cm 3 ·g -1 , the mesopore volume is 0.34 cm 3 ·g -1 ; The grain size of the multi-level pore high-silicon Y-type molecular sieve is 0.6-1.2μm; the relative crystallinity of the multi-level pore high-silicon Y-type molecular sieve is above 85%.

[0067] In the experimental methods of the following examples, unless otherwise specified, they are all conventional methods; the reagents and materials, unless otherwise specified, can all be obtained from commercial channels.

[0068] Analysis method: For the detection and confirmation of the phase, a Shimadzu XRD-7000 X-ray powder diffractometer for crystals was used; instrument parameters: Cu-Kα ray, wavelength of 0.1543 nm, tube voltage of 40 kV, and tube current of 30 mA. Test conditions for the sample: scanning angle of 5 - 40°, scanning speed of 8° / min. For the analysis using an X-ray fluorescence spectrometer (XRF), a Shimadzu XRF-1800 was used. Before the test, 200 mg of the powder was pressed into a tablet.

[0069] Preparation of kaolin microspheres A:

[0070] 3500 g (dry basis) of kaolin, 140 g of NaY zeolite with a crystal grain size of 1 μm, relative crystallinity of 95%, and silica-alumina ratio of 3.5, 100 g of sodium silicate, 35 g of sodium polyacrylate, and water were mixed to form a slurry with a solid content of 30%. After spray forming, 2400 g of kaolin microspheres A with an average particle size of 50 μm were obtained.

[0071] Preparation of kaolin microspheres B:

[0072] 3500 g (dry basis) of kaolin, 140 g of NaY zeolite with a crystal grain size of 0.5 μm, relative crystallinity of 98%, and silica-alumina ratio of 4, 100 g of sodium silicate, 35 g of sodium polyacrylate, and water were mixed to form a slurry with a solid content of 45%. After spray forming, 2650 g of kaolin microspheres B with an average particle size of 20 μm were obtained.

[0073] Preparation of kaolin microspheres C:

[0074] 3500 g (dry basis) of kaolin, 140 g of NaY zeolite with a crystal grain size of 1.5 μm, relative crystallinity of 99%, and silica-alumina ratio of 5.5, 100 g of sodium silicate, 35 g of sodium polyacrylate, and water were mixed to form a slurry with a solid content of 55%. After spray forming, 2800 g of kaolin microspheres C with an average particle size of 110 μm were obtained.

[0075] Among them, in the preparation of kaolin microspheres A, kaolin microspheres B, and kaolin microspheres C, the kaolin used was soft kaolin with a particle size of 3 - 10 μm. Based on the total mass of the kaolin being 100%, the alumina content was 42.5%, the silica content was 55.3%, the iron oxide content was less than 1.7%, and the sum of the sodium oxide and potassium oxide contents was less than 0.5%. The spray drying and forming were carried out in a spray dryer, and its operating conditions were: the hot air inlet temperature was controlled at 120 °C, the sample injection flow rate was 20%, and the atomizing air flow rate was 500 L / h.

[0076] Example 1

[0077] This example provides a hierarchical pore high-silica Y-type zeolite synthesized by in-situ crystallization of kaolin microspheres, which is prepared by the following steps:

[0078] Take an appropriate amount of kaolin microsphere A and calcine it in a muffle furnace at 750 °C for 5 h to obtain CKM microsphere A; mix the water glass treated with 2-hydroxybutanedioic acid, the sodium hydroxide solution with a mass concentration of 20%, and CKM microsphere A according to the molar ratio of n(Na2O):n(Al2O3):n(SiO2):n(H2O) = 15:1:20:500, then add a mixed solution of sodium persulfate and Fe 3+ solution (iron chloride solution), and stir for 4 h (the stirring speed is 150 r / min) under the condition of a 40 °C water bath to obtain a gel system. Among them, the water glass treated with 2-hydroxybutanedioic acid is obtained by the following method: take an appropriate amount of water glass and add it to a beaker, place it in a 35 °C water bath, add 2-hydroxybutanedioic acid, mix evenly and let it stand for 3 h. Among them, the mass ratio of water glass to 2-hydroxybutanedioic acid is 1:1.5 to obtain the water glass treated with 2-hydroxybutanedioic acid; the addition amount of the Fe 3+ solution is 5% of the molar amount of Al2O3 in the gel system, and the addition amount of sodium persulfate is 7% of the molar amount of Al2O3 in the gel system; then transfer the gel system to a polytetrafluoroethylene reaction kettle, carry out static crystallization at 95 °C for 12 h, and then after filtration and washing, dry at 60 °C for 18 h to obtain NaY zeolite microsphere YKM.

[0079] It is determined by an X-ray diffractometer that the YKM in this example contains 42% NaY. Its silicon-aluminum ratio is 6.1 measured by an X-ray fluorescence spectrometer. The mesopore volume of the NaY zeolite in this example is 0.29 cm 3 / g.

[0080] Example 2

[0081] This example provides a hierarchical pore high-silica Y-type zeolite synthesized by in-situ crystallization of kaolin microspheres, which is prepared by the following steps:

[0082] Take an appropriate amount of kaolin microsphere B and calcine it in a muffle furnace at 850 °C for 2 h to obtain CKM microsphere B; mix the water glass treated with tartaric acid, the sodium hydroxide solution with a mass concentration of 20%, and CKM microsphere B according to the molar ratio of n(Na2O):n(Al2O3):n(SiO2):n(H2O) = 5.2:1:8.4:200, then add sodium persulfate and Fe 3+A mixed solution (ferric chloride solution), stirred for 4 h under the condition of a 30 °C water bath (the stirring speed is 150 r / min) to obtain a gel system. Among them, the tartaric acid-treated sodium silicate is obtained by the following method: Take an appropriate amount of sodium silicate and add it to a beaker, place it in a 50 °C water bath, add tartaric acid, mix evenly and let it stand for 3 h. Among them, the mass ratio of sodium silicate to tartaric acid is 1:1.5 to obtain the tartaric acid-treated sodium silicate; the Fe 3+ The addition amount of the solution is 5% of the molar amount of Al2O3 in the gel system, and the addition amount of sodium persulfate is 7% of the molar amount of Al2O3 in the gel system; then transfer the gel system to a polytetrafluoroethylene reaction kettle, crystallize statically at 96 °C for 12 h, and then after filtration and washing, dry at 80 °C for 12 h to obtain the NaY molecular sieve microspheres YKM.

[0083] It is determined by an X-ray diffractometer that the YKM in this example contains 56% NaY, and its silica-alumina ratio is 6.6 determined by an X-ray fluorescence spectrometer. Figure 1 This is the characteristic X-ray diffraction pattern of the hierarchical pore high-silica Y-type molecular sieve microspheres provided in this example. The specific surface area of the NaY molecular sieve in this example is 737 m 2 ·g -1 , the micropore volume is 0.20 cm 3 ·g -1 , the mesopore volume is 0.34 cm 3 / g. The average particle size of the NaY molecular sieve microspheres YKM in this example is 16 μm, its crystal grain size is 0.6 μm, and the relative crystallinity is 89%.

[0084] Example 3

[0085] This example provides a hierarchical pore high-silica Y-type molecular sieve synthesized by in-situ crystallization of kaolin microspheres, which is prepared by the following steps:

[0086] Take an appropriate amount of kaolin microspheres C and calcine them in a muffle furnace at 750 °C for 5 h to obtain CKM microspheres C; mix the citric acid-treated sodium silicate, 20% sodium hydroxide solution by mass concentration, and CKM microspheres C according to the molar ratio of n(Na2O):n(Al2O3):n(SiO2):n(H2O)=1:1:10:200, and then add sodium persulfate and Fe 3+ A mixed solution (ferric chloride solution), stirred for 4 h under the condition of a 25 °C water bath (the stirring speed is 150 r / min) to obtain a gel system. Among them, the citric acid-treated sodium silicate is obtained by the following method: Take an appropriate amount of sodium silicate and add it to a beaker, place it in a 40 °C water bath, add citric acid, mix evenly and let it stand for 3 h. Among them, the mass ratio of sodium silicate to citric acid is 1:2 to obtain the citric acid-treated sodium silicate; the Fe3+ The addition amount of the solution is 5% of the molar amount of Al2O3 in the gel system, and the addition amount of the sodium persulfate is 7% of the molar amount of Al2O3 in the gel system; then the gel system is transferred to a polytetrafluoroethylene reaction kettle, statically crystallized at 100 °C for 48 h, and then after filtration and washing, dried at 70 °C for 15 h to obtain the NaY molecular sieve microspheres YKM.

[0087] It is determined by an X-ray diffractometer that the YKM in this example contains 61% NaY. Its silicon-aluminum ratio is 6.2 measured by an X-ray fluorescence spectrometer. The mesopore volume of the NaY molecular sieve in this example is 0.31 cm 3 / g.

[0088] Example 4

[0089] This example provides a hierarchical pore high-silica Y-type molecular sieve synthesized by in-situ crystallization of kaolin microspheres, which is prepared by the following steps:

[0090] Take an appropriate amount of kaolin microspheres B and calcine them in a muffle furnace at 850 °C for 2 h to obtain CKM microspheres B; mix the water glass treated with tartaric acid, the sodium hydroxide solution with a mass concentration of 20%, and CKM microspheres B according to the molar ratio of n(Na2O):n(Al2O3):n(SiO2):n(H2O) = 30:1:10:400, and then add a mixed solution of hydrogen peroxide and Cu 2+ solution (copper chloride solution), and stir for 4 h (the stirring speed is 150 r / min) under the water bath condition at 80 °C to obtain a gel system. Among them, the water glass treated with tartaric acid is obtained by the following method: take an appropriate amount of water glass and add it to a beaker, place it in a water bath at 40 °C, add tartaric acid, mix evenly and let it stand for 3 h. Among them, the mass ratio of water glass to tartaric acid is 1:2 to obtain the water glass treated with tartaric acid; the addition amount of the Cu 2+ solution is 5% of the molar amount of Al2O3 in the gel system, and the addition amount of the hydrogen peroxide is 7% of the molar amount of Al2O3 in the gel system; then the gel system is transferred to a polytetrafluoroethylene reaction kettle, statically crystallized at 96 °C for 24 h, and then after filtration and washing, dried at 90 °C for 12 h to obtain the NaY molecular sieve microspheres YKM.

[0091] It is determined by an X-ray diffractometer that the YKM in this example contains 56% NaY. Its silicon-aluminum ratio is 6.5 measured by an X-ray fluorescence spectrometer. The mesopore volume of the NaY molecular sieve in this example is 0.33 cm 3 / g.

[0092] Example 5

[0093] This example provides a hierarchical pore high-silica Y-type zeolite synthesized by in-situ crystallization of kaolin microspheres, which is prepared through the following steps:

[0094] Take an appropriate amount of kaolin microsphere B and calcine it in a muffle furnace at 850 °C for 2 h to obtain CKM microsphere B; mix the citric acid-treated water glass, a sodium hydroxide solution with a mass concentration of 20%, and 20 g of CKM microsphere B according to the molar ratio of n(Na2O):n(Al2O3):n(SiO2):n(H2O) = 10:1:20:800, then add a mixed solution of potassium persulfate and Ni 2+ solution (nickel chloride solution), and stir for 4 h (the stirring speed is 150 r / min) under a water bath condition of 30 °C to obtain a gel system. Among them, the citric acid-treated water glass is obtained through the following method: Take an appropriate amount of water glass and add it to a beaker, place it in a water bath at 70 °C, add citric acid, mix evenly and then let it stand for 3 h. Among them, the mass ratio of water glass to citric acid is 1:3 to obtain the citric acid-treated water glass; the addition amount of the Ni 2+ solution is 5% of the molar amount of Al2O3 in the gel system, and the addition amount of potassium persulfate is 7% of the molar amount of Al2O3 in the gel system; then transfer the gel system to a polytetrafluoroethylene reaction kettle, carry out static crystallization at 120 °C for 24 h, and then after filtration and washing, dry it at 80 °C for 12 h to obtain NaY zeolite microsphere YKM.

[0095] It is determined by an X-ray diffractometer that YKM in this example contains 58% NaY. Its silica-alumina ratio is 6.4 as determined by an X-ray fluorescence spectrometer. The mesoporous pore volume of the NaY zeolite in this example is 0.31 cm 3 / g.

[0096] Example 6

[0097] This example provides a hierarchical pore high-silica Y-type zeolite synthesized by in-situ crystallization of kaolin microspheres, which is prepared through the following steps:

[0098] Take an appropriate amount of kaolin microsphere B and calcine it in a muffle furnace at 850 °C for 2 h to obtain CKM microsphere B; mix the 2-hydroxybutanedioic acid-treated water glass, a sodium hydroxide solution with a mass concentration of 20%, and CKM microsphere B according to the molar ratio of n(Na2O):n(Al2O3):n(SiO2):n(H2O) = 20:1:10:400, then add sodium persulfate and Mn 6+A mixed solution (potassium manganate solution), stirred for 4 h (stirring speed is 150 r / min) under the condition of 30 °C water bath, to obtain a gel system. Among them, the water glass treated with 2-hydroxybutanedioic acid is obtained by the following method: Take an appropriate amount of water glass and add it to a beaker, place it in a 40 °C water bath, add 2-hydroxybutanedioic acid, mix evenly and let it stand for 3 h. Among them, the mass ratio of water glass to 2-hydroxybutanedioic acid is 1:1.5, to obtain the water glass treated with 2-hydroxybutanedioic acid; the Mn 6+ The addition amount of the solution is 5% of the molar amount of Al2O3 in the gel system, and the addition amount of sodium persulfate is 7% of the molar amount of Al2O3 in the gel system; then transfer the gel system to a polytetrafluoroethylene reaction kettle, carry out static crystallization at 110 °C for 16 h, and then after filtration and washing, dry at 80 °C for 12 h to obtain the NaY molecular sieve microspheres YKM.

[0099] It is determined by an X-ray diffractometer that the YKM in this example contains 51% NaY. After being determined by an X-ray fluorescence spectrometer, its silica-alumina ratio is 6.3. The mesopore volume of the NaY molecular sieve in this example is 0.32 cm 3 / g.

[0100] Example 7

[0101] This example provides a hierarchical pore high-silica Y-type molecular sieve synthesized by in-situ crystallization of kaolin microspheres, which is prepared by the following steps:

[0102] Take an appropriate amount of kaolin microspheres B and calcine them in a muffle furnace at 850 °C for 2 h to obtain CKM microspheres B; Mix the water glass treated with tartaric acid, the sodium hydroxide solution with a mass concentration of 20%, and CKM microspheres B according to the molar ratio of n(Na2O):n(Al2O3):n(SiO2):n(H2O) = 5:1:20:200, and then add hydrogen peroxide and Mn 7+ A mixed solution (potassium permanganate solution), stirred for 4 h (stirring speed is 150 r / min) under the condition of 30 °C water bath, to obtain a gel system. Among them, the water glass treated with tartaric acid is obtained by the following method: Take an appropriate amount of water glass and add it to a beaker, place it in a 60 °C water bath, add tartaric acid, mix evenly and let it stand for 3 h. Among them, the mass ratio of water glass to tartaric acid is 1:2, to obtain the water glass treated with tartaric acid; the Mn 7+ The addition amount of the solution is 5% of the molar amount of Al2O3 in the gel system, and the addition amount of hydrogen peroxide is 7% of the molar amount of Al2O3 in the gel system; then transfer the gel system to a polytetrafluoroethylene reaction kettle, carry out static crystallization at 110 °C for 48 h, and then after filtration and washing, dry at 80 °C for 12 h to obtain the NaY molecular sieve microspheres YKM.

[0103] It was determined by X-ray diffractometer that the YKM in this example contains 48% NaY. Its silica-alumina ratio was determined by X-ray fluorescence spectrometer to be 6.1. The mesopore volume of the NaY molecular sieve in this example is 0.31 cm 3 / g.

[0104] Example 8

[0105] This example provides a hierarchically porous high-silica Y-type molecular sieve synthesized by in-situ crystallization of kaolin microspheres, which is prepared by the following steps:

[0106] Take an appropriate amount of kaolin microsphere B and calcine it in a muffle furnace at 850 °C for 2 h to obtain CKM microsphere B; mix tetraethyl orthosilicate treated with tartaric acid, a sodium hydroxide solution with a mass concentration of 20%, and CKM microsphere B according to the molar ratio of n(Na2O):n(Al2O3):n(SiO2):n(H2O) = 20:1:1:200, and then add a mixed solution of sodium persulfate and Cu 2+ solution (copper chloride solution), and stir at 30 °C in a water bath for 4 h (the stirring speed is 150 r / min) to obtain a gel system. Among them, the tetraethyl orthosilicate treated with tartaric acid is obtained by the following method: take an appropriate amount of tetraethyl orthosilicate and add it to a beaker, place it in a water bath at 60 °C, add tartaric acid, mix evenly and let it stand for 3 h. Among them, the mass ratio of tetraethyl orthosilicate to tartaric acid is 1:1.5 to obtain the tetraethyl orthosilicate treated with tartaric acid; the addition amount of the Cu 2+ solution is 5% of the molar amount of Al2O3 in the gel system, and the addition amount of sodium persulfate is 7% of the molar amount of Al2O3 in the gel system; then transfer the gel system to a polytetrafluoroethylene reaction kettle, carry out static crystallization at 96 °C for 24 h, then filter and wash, and dry at 80 °C for 12 h to obtain NaY molecular sieve microspheres YKM.

[0107] It was determined by X-ray diffractometer that the YKM in this example contains 56% NaY. Its silica-alumina ratio was determined by X-ray fluorescence spectrometer to be 6.4. The mesopore volume of the NaY molecular sieve in this example is 0.34 cm 3 / g.

[0108] Comparative Example 1

[0109] This comparative example provides a Y-type molecular sieve synthesized by in-situ crystallization of kaolin microspheres, which uses the same preparation conditions as in Example 2, except that Fe is not added during the synthesis process 3+Solution, and an appropriate amount of sodium persulfate was added. The preparation process was as follows: An appropriate amount of kaolin microsphere B was calcined in a muffle furnace at 850 °C for 2 h to obtain CKM microsphere B; the water glass treated with tartaric acid, the sodium hydroxide solution with a mass concentration of 20%, and CKM microsphere B were mixed according to the molar ratio of n(Na2O):n(Al2O3):n(SiO2):n(H2O) = 5.2:1:8.4:200, and then sodium persulfate was added. The mixture was stirred in a water bath at 30 °C for 4 h (the stirring speed was 150 r / min) to obtain a gel system. Among them, the water glass treated with tartaric acid was obtained by the following method: An appropriate amount of water glass was added to a beaker, placed in a water bath at 50 °C, tartaric acid was added, and after mixing evenly, it was left standing for 3 h. Among them, the mass ratio of water glass to tartaric acid was 1:1.5 to obtain the water glass treated with tartaric acid; the addition amount of sodium persulfate was 15% of the molar amount of Al2O3 in the gel system; then the gel system was transferred to a polytetrafluoroethylene reaction kettle, statically crystallized at 96 °C for 12 h, and then after filtration and washing, it was dried at 80 °C for 12 h to obtain NaY zeolite microsphere YKM.

[0110] It was determined by an X-ray diffractometer that the YKM in this comparative example contained 40% NaY. The silicon-aluminum ratio was measured by an X-ray fluorescence spectrometer to be 5.2. The mesoporous pore volume of the NaY zeolite in this comparative example was 0.34 cm 3 / g.

[0111] Comparative Example 2

[0112] This comparative example provided a Y-type zeolite synthesized by in-situ crystallization of kaolin microspheres, which used the same preparation conditions as in Example 2, except that Fe 3+ solution was not added during the synthesis process. The preparation process was as follows: An appropriate amount of kaolin microsphere B was calcined in a muffle furnace at 850 °C for 2 h to obtain CKM microsphere B; the water glass treated with tartaric acid, the sodium hydroxide solution with a mass concentration of 20%, and CKM microsphere B were mixed according to the molar ratio of n(Na2O):n(Al2O3):n(SiO2):n(H2O) = 5.2:1:8.4:200, and then sodium persulfate was added. The mixture was stirred in a water bath at 30 °C for 4 h (the stirring speed was 150 r / min) to obtain a gel system. Among them, the water glass treated with tartaric acid was obtained by the following method: An appropriate amount of water glass was added to a beaker, placed in a water bath at 50 °C, tartaric acid was added, and after mixing evenly, it was left standing for 3 h. Among them, the mass ratio of water glass to tartaric acid was 1:1.5 to obtain the water glass treated with tartaric acid; the addition amount of sodium persulfate was 7% of the molar amount of Al2O3 in the gel system; then the gel system was transferred to a polytetrafluoroethylene reaction kettle, statically crystallized at 96 °C for 12 h, and then after filtration and washing, it was dried at 80 °C for 12 h to obtain NaY zeolite microsphere YKM.

[0113] It was determined by X-ray diffractometer that the YKM in this comparative example contained 45% NaY. Its silica-alumina ratio was 4.7 determined by X-ray fluorescence spectrometer. The mesopore volume of the NaY molecular sieve in this comparative example was 0.34 cm 3 / g.

[0114] Comparative Example 3

[0115] This comparative example provided a Y-type molecular sieve synthesized by in-situ crystallization of kaolin microspheres, which used the same preparation conditions as in Example 2, except that sodium persulfate was not added during the synthesis process. The preparation process was as follows: Take an appropriate amount of kaolin microsphere B and calcine it in a muffle furnace at 850 °C for 2 h to obtain CKM microsphere B; Mix the water glass treated with tartaric acid, the sodium hydroxide solution with a mass concentration of 20%, and CKM microsphere B according to the molar ratio of n(Na2O):n(Al2O3):n(SiO2):n(H2O) = 5.2:1:8.4:200, and then add Fe 3+ solution (iron chloride solution), and stir for 4 h (the stirring speed is 150 r / min) under the condition of a 30 °C water bath to obtain a gel system. Among them, the water glass treated with tartaric acid was obtained by the following method: Take an appropriate amount of water glass and add it to a beaker, place it in a 50 °C water bath, add tartaric acid, mix evenly and then stand for 3 h. The mass ratio of water glass to tartaric acid was 1:1.5 to obtain the water glass treated with tartaric acid; The addition amount of the Fe 3+ solution was 5% of the molar amount of Al2O3 in the gel system; Then transfer the gel system to a polytetrafluoroethylene reaction kettle, carry out static crystallization at 96 °C for 12 h, and then after filtration and washing, dry at 80 °C for 12 h to obtain the NaY molecular sieve microsphere YKM.

[0116] It was determined by X-ray diffractometer that the YKM in this comparative example contained 40% NaY. Its silica-alumina ratio was 4.2 determined by X-ray fluorescence spectrometer. The mesopore volume of the NaY molecular sieve in this comparative example was 0.34 cm 3 / g.

[0117] Comparative Example 4

[0118] This comparative example provides a Y-type molecular sieve synthesized by in-situ crystallization of kaolin microspheres, which uses the same preparation conditions as in Example 2, except that in the synthesis process, sodium silicate treated with tartaric acid is not used, but sodium silicate is directly used. The preparation process is as follows: Take an appropriate amount of kaolin microsphere B and calcine it in a muffle furnace at 850 °C for 2 h to obtain CKM microsphere B; Mix sodium silicate, a sodium hydroxide solution with a mass concentration of 20%, and CKM microsphere B according to the molar ratio of n(Na2O):n(Al2O3):n(SiO2):n(H2O) = 5.2:1:8.4:200, and then add a mixed solution of sodium persulfate and Fe 3+ solution (iron chloride solution), and stir for 4 h under a water bath condition of 30 °C (the stirring speed is 150 r / min) to obtain a gel system. The addition amount of the Fe 3+ solution is 5% of the molar amount of Al2O3 in the gel system, and the addition amount of sodium persulfate is 7% of the molar amount of Al2O3 in the gel system; Then transfer the gel system to a polytetrafluoroethylene reaction kettle, carry out static crystallization at 96 °C for 12 h, and then after filtration and washing, dry at 80 °C for 12 h to obtain NaY molecular sieve microsphere YKM.

[0119] It is determined by an X-ray diffractometer that the YKM in this comparative example contains 40% NaY. Its silicon-aluminum ratio is 6.5 as determined by an X-ray fluorescence spectrometer. The mesopore volume of the NaY molecular sieve in this comparative example is 0.09 cm 3 / g.

[0120] Comparative Example 5

[0121] This comparative example provides a Y-type molecular sieve synthesized by in-situ crystallization of kaolin microspheres, which uses the same preparation conditions as in Example 2, except that in the synthesis process, the Fe 3+ solution is replaced with a Co 2+ solution. The preparation process is as follows: Take an appropriate amount of kaolin microsphere B and calcine it in a muffle furnace at 850 °C for 2 h to obtain CKM microsphere B; Mix sodium silicate treated with tartaric acid, a sodium hydroxide solution with a mass concentration of 20%, and CKM microsphere B according to the molar ratio of n(Na2O):n(Al2O3):n(SiO2):n(H2O) = 5.2:1:8.4:200, and then add a mixed solution of sodium persulfate and Co 2+ solution (cobalt chloride solution), and stir for 4 h under a water bath condition of 30 °C (the stirring speed is 150 r / min) to obtain a gel system. Among them, the sodium silicate treated with tartaric acid is obtained by the following method: Take an appropriate amount of sodium silicate and add it to a beaker, place it in a water bath at 50 °C, add tartaric acid, mix evenly and let it stand for 3 h. The mass ratio of sodium silicate to tartaric acid is 1:1.5 to obtain the sodium silicate treated with tartaric acid; The Co 2+The addition amount of the solution is 5% of the molar amount of Al2O3 in the gel system, and the addition amount of the sodium persulfate is 7% of the molar amount of Al2O3 in the gel system; then the gel system is transferred to a polytetrafluoroethylene reaction kettle, statically crystallized at 96 °C for 12 h, and then after filtration and washing, dried at 80 °C for 12 h to obtain the NaY molecular sieve microspheres YKM.

[0122] It is determined by an X-ray diffractometer that the YKM in this comparative example contains 50% NaY. The silicon-aluminum ratio is measured to be 4.4 by an X-ray fluorescence spectrometer. The mesopore volume of the NaY molecular sieve in this comparative example is 0.33 cm 3 / g.

[0123] In summary, the present invention provides a method for in-situ crystallization synthesis of hierarchical pore high-silica Y-type molecular sieve from kaolin microspheres. In the present invention, kaolin, solid seeds, an organic dispersant, a binder, etc. are spray-dried and formed into kaolin microspheres; the kaolin microspheres are calcined at high temperature for activation, and then stirred and mixed evenly with a silicon source treated with a weak acid, transition metal ions, and a hydroxyl radical initiator. After crystallization, a hierarchical pore high-silica Y-type molecular sieve is synthesized. The present invention uses transition metal ions to promote the generation of a large amount of hydroxyl radicals, accelerate the formation of Si-O-Si bonds, and promote the dissolution of active silicon in the kaolin microspheres, thereby increasing the silicon-aluminum ratio of the Y-type molecular sieve and obtaining high-silica Y. At the same time, the present invention pretreats the silicon source with an organic weak acid. The treated silicon source will form highly polymerized silicate anions. After the weak acid dissolves in the system, it combines with sodium ions to form sodium salts, which can enter between the molecular sieve lattices during the crystallization process and react to release carbon dioxide during calcination, generating mesopores. Therefore, the present invention provides a method for synthesizing hierarchical pore high-silica Y-type molecular sieve microspheres, which has the advantages of simple synthesis route and low cost.

Claims

1. A preparation method of a hierarchical pore high-silica Y zeolite synthesized in-situ from kaolin microspheres, which comprises the following steps: (1) Mix kaolin, a dispersant, a binder, seeds of Y zeolite, and water to obtain a slurry; Form the slurry into kaolin microspheres, and then calcine the kaolin microspheres to obtain activated kaolin microspheres; (2) Mix at least the activated kaolin microspheres, the silicon source treated with weak acid, transition metal ions and a hydroxyl radical initiator to obtain a gel system; the weak acid used for the silicon source treated with weak acid includes one or a combination of tartaric acid, 2-hydroxybutanedioic acid, and citric acid, and the transition metal ions include Fe 3+ , Cu 2+ , Mn 6+ , Mn 7+ and Ni 2+ or a combination of several of them, and the hydroxyl radical initiator includes one or a combination of sodium persulfate, potassium persulfate, and hydrogen peroxide; after the gel system is crystallized, it is at least dried to obtain the hierarchical porous high-silica Y zeolite.

2. The preparation method according to claim 1, wherein, In step (1), the kaolin includes soft kaolin.

3. The preparation method according to claim 1, wherein, In step (1), the particle size of the kaolin is 3 - 10 μm.

4. The preparation method according to claim 1, wherein, In step (1), based on the total mass of the kaolin being 100%, the alumina content is 40% - 45%, the silica content is 52.8% - 58%, the iron oxide content is below 1.7%, and the sum of the sodium oxide and potassium oxide contents is below 0.5%.

5. The preparation method according to claim 1 or 2, wherein, In step (1), the mixing mass ratio of the dispersant to the kaolin is (1 - 3):

100.

6. The preparation method according to claim 1, wherein, In step (1), the dispersant includes sodium polyacrylate.

7. The preparation method according to claim 1, wherein, In step (1), the mixing mass ratio of the binder to the kaolin is 0.16 - 0.

33.

8. The preparation method according to claim 1, wherein, In step (1), the binder includes one or a combination of several of sodium silicate, water glass, and silica sol.

9. The preparation method according to claim 1, wherein, In step (1), the mixing mass ratio of the seeds of Y zeolite to the kaolin is (1 - 20):

100.

10. The preparation method according to claim 9, wherein, In step (1), the mixing mass ratio of the seeds of Y zeolite to the kaolin is (1 - 15):

100.

11. The preparation method according to claim 1, wherein, In step (1), the seeds of Y zeolite are solid seeds of Y zeolite, including one or a combination of several of NaY zeolite, HY zeolite, and USY zeolite; the crystal grain size of the seeds of Y zeolite is 0.5 - 1.5 μm, the relative crystallinity is 95% - 99%, and the silica-alumina ratio is 3.5 - 5.

5.

12. The preparation method according to claim 1, wherein, In step (1), the solid content of the slurry is 30 - 55%.

13. The preparation method according to claim 1, wherein, In step (1), the particle size of the kaolin microspheres obtained by forming is 20 - 110 μm.

14. The preparation method according to claim 13, wherein, In step (1), the forming includes spray drying forming.

15. According to the preparation method described in claim 1, wherein In step (1), the calcination temperature of the kaolin microspheres is 750 - 1000 °C, and the calcination time is 1 - 5 h.

16. The preparation method according to claim 1, wherein, In step (2), in addition to mixing the activated kaolin microspheres, a weakly acid-treated silicon source, transition metal ions, and a hydroxyl radical initiator, an alkali source and / or water are also included to obtain the gel system.

17. The preparation method according to claim 1 or 16, wherein In step (2), the pH value of the gel system is 10 - 14.

18. The preparation method according to claim 1, wherein, In step (2), the gel system is prepared by the following method: mix the activated kaolin microspheres, a weakly acid-treated silicon source, an alkali source that can be optionally added or not added, and water that can be optionally added or not added to obtain a first mixture; mix the transition metal ions and the hydroxyl radical initiator to obtain a first mixed solution; mix the first mixture with the first mixed solution to obtain the gel system.

19. The preparation method according to claim 18, wherein, In step (2), the molar ratio of Na2O:Al2O3:SiO2:H2O in the first mixture is (1 - 30):1:(1 - 40):(200 - 800).

20. The preparation method according to claim 1, wherein, In step (2), the silicon source used for the silicon source treated with weak acid includes one or a combination of several of sodium silicate, sodium metasilicate, and tetraethyl orthosilicate.

21. The preparation method according to claim 1, wherein, In step (2), the silicon source treated with weak acid is obtained by the following method: the silicon source and weak acid are mixed evenly at a mass ratio of 1:(1.5 - 3), and then left standing for 2 - 4 h to obtain the silicon source treated with weak acid.

22. The preparation method according to claim 21, wherein, In step (2), the temperature for the mixing and standing is 35 - 70 °C.

23. The preparation method according to claim 1, wherein, In step (2), the addition amount of the transition metal ions is 1% - 5% of the molar amount of Al2O3 in the gel system.

24. The preparation method according to claim 1, wherein In step (2), the addition amount of the hydroxyl radical initiator is 1% - 7% of the molar amount of Al2O3 in the gel system.

25. The preparation method according to claim 1, wherein, In step (2), the temperature for mixing the activated kaolin microspheres, the silicon source treated with weak acid, the transition metal ions, and the hydroxyl radical initiator is 25 - 80 °C.

26. The preparation method according to claim 25, wherein In step (2), the mixing is carried out under stirring conditions, and the stirring time is 2 - 5 h.

27. The preparation method according to claim 1, wherein In step (2), the crystallization temperature is 90 - 120 °C, and the time is 12 - 48 h.

28. A hierarchical pore high-silica Y-type zeolite synthesized in-situ from kaolin microspheres, which is prepared by the preparation method of the hierarchical pore high-silica Y-type zeolite synthesized in-situ from kaolin microspheres according to any one of claims 1 - 27.

29. The hierarchically porous high-silica Y zeolite synthesized in-situ from kaolin microspheres according to claim 28, wherein, The silicon-aluminum ratio of the hierarchical pore high-silica Y-type zeolite synthesized in-situ from kaolin microspheres is 6.0 or more.

30. The hierarchically porous high-silica Y zeolite synthesized in situ from kaolin microspheres according to claim 28, wherein, The crystal grain size of the hierarchical pore high-silica Y-type zeolite synthesized in-situ from kaolin microspheres is 0.6 - 1.2 μm.

31. The hierarchically porous high-silica Y zeolite synthesized in-situ from kaolin microspheres according to claim 28, wherein, The hierarchically porous high-silica Y zeolite synthesized in situ from kaolin microspheres has a microporous structure and a mesoporous structure. The specific surface area of the hierarchically porous high-silica Y zeolite is 700 - 790 m 2 ·g -1 , the micropore volume is 0.15 - 0.30 cm 3 ·g -1 , and the mesopore volume is 0.25 - 0.40 cm 3 ·g -1 .

32. The hierarchically porous high-silica Y zeolite synthesized in situ from kaolin microspheres according to claim 28, wherein, The hierarchical pore high-silica Y-type zeolite synthesized in-situ from kaolin microspheres is a hierarchical pore high-silica Y-type zeolite microsphere. Based on the total mass of the hierarchical pore high-silica Y-type zeolite microsphere being 100%, the content of the hierarchical pore high-silica Y-type zeolite therein is 40 - 65%.

33. The hierarchically porous high-silica Y zeolite synthesized in situ from kaolin microspheres according to claim 32, wherein, The particle size of the hierarchical pore high-silica Y-type zeolite microsphere is 15 - 100 μm.

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