A nano-scale high-silica Y zeolite, its preparation method and application

Abstract

The present application discloses a nano-scale high-silica Y zeolite and its synthesis method and application. The silica-alumina ratio of the nano-scale high-silica zeolite is 5 to 25, the size of the nano-scale high-silica Y zeolite is 10 to 100 nm, and the nano-scale high-silica Y zeolite has intercrystalline mesopores. The synthesis method of the Y zeolite includes first preparing a directing agent, and then adding the directing agent to a synthesis system for crystallization to synthesize a nano-scale high-silica Y zeolite. In addition, the present application provides the application of the above Y zeolite in catalytic cracking of, for example, cumene and triisopropylbenzene. The preparation method of the Y zeolite of the present application is simple, the product has high crystallinity and purity, and has high catalytic activity in catalytic cracking reactions.

Description

Technical Field

[0001] The present application relates to a nano-sized high-silica Y zeolite and its preparation method and application, and more specifically to a high-silica Y zeolite with nano-sized crystal grains. A method for directly synthesizing nano-sized high-silica Y zeolite by directly introducing a zeolite growth inhibitor into the synthesis system and adding a directing agent belongs to the field of catalysis. Background Art

[0002] Zeolites are a class of microporous solid materials with a crystal structure composed of silicon-oxygen and aluminum-oxygen tetrahedra as structural units. Zeolites are widely used in adsorption separation, ion exchange, catalytic conversion and other fields due to their high specific surface area, rich active sites and good thermal stability. Among them, Y zeolite is a silicon-aluminum zeolite with a FAU topological structure and is mainly used in fluid catalytic cracking (FCC) reactions. It is currently the most used zeolite material. The framework silicon-aluminum ratio of Y zeolite plays a decisive role in its catalytic performance. The higher the silicon-aluminum ratio, the better the catalytic activity and stability.

[0003] In catalytic reactions, the microporous structure of zeolites themselves is relatively small, usually less than 1 nm, which limits the contact between macromolecular reactants and active sites and the diffusion of products. Compared with conventional zeolites, nano-sized zeolites have the advantages of a high number of exposed active sites and less diffusion limitation. Moreover, as the size of nano-zeolites decreases, their specific surface area, the number of available active sites and catalytic reaction efficiency increase significantly.

[0004] Currently, the Y zeolites commonly used in industry are mainly obtained by dealumination through post-treatment methods. Post-treatment can not only increase the framework silicon-aluminum ratio of zeolites but also generate a hierarchical pore structure. These treatment processes are complex, time-consuming and energy-consuming. The crystallinity of the obtained products drops sharply, and there will also be a dealumination gradient on the surface and inside of the product crystals, which is extremely likely to cause uneven distribution of acid centers. Summary of the Invention

[0005] In order to overcome the above technical problems in the prior art, the present application provides a method for directly synthesizing nano-sized high-silica Y zeolite. This method has low energy consumption, the synthesized zeolite has a well-tunable nano-sized dimension, the aluminum in the zeolite is evenly distributed, the available active sites are rich, it has good thermal stability and hydrothermal stability, and high crystallinity. It is an ideal catalytic material.

[0006] According to the first aspect of the present application, there is provided a high-silica Y zeolite with nano-sized dimension, which can be applied to catalytic cracking (such as cumene and tri-isopropylbenzene), hydrocracking and other reactions, and has good catalytic reaction activity.

[0007] Specifically, the anhydrous chemical composition of the nano-sized high-silica Y zeolite is shown in Formula I:

[0008] kM·mR1·nR2·pT·(Si x Al y )O2 of formula I

[0009] wherein M is selected from at least one of alkali metal elements;

[0010] T represents a molecular sieve growth inhibitor;

[0011] R1 represents a first organic template; R2 represents a second organic template, and R1 is different from R2;

[0012] k represents the molar number of alkali metal element corresponding to per mole of (Si x Al y )O2, k = 0.01 - 0.20;

[0013] m, n represent the molar numbers of organic templates R1, R2 corresponding to per mole of (Si x Al y )O2, m = 0.01 - 0.2; n = 0.01 - 0.4;

[0014] p represents the molar number of growth inhibition monomer corresponding to per mole of (Si x Al y )O2, p = 0.001 - 0.20;

[0015] x, y respectively represent the molar fractions of Si, Al, 2x / y = 5 - 25, x + y = 1;

[0016] The size of the nanoscale high-silica Y zeolite is 10 - 100 nm;

[0017] The nanoscale high-silica Y zeolite has intercrystalline mesopores.

[0018] Optionally, the nanoscale high-silica Y zeolite includes micropores;

[0019] The specific surface area of the micropores is 480 - 820 m 2 / g;

[0020] The volume of the micropores is 0.23 - 0.40 cm 3 / g;

[0021] The external surface area is 50 - 415 m 2 / g;

[0022] The volume of the intercrystalline mesopores is 0.05 - 0.30 cm 3 / g.

[0023] Optionally, k = 0.01 to 0.15; m = 0.01 to 0.12; n = 0.01 to 0.30; p = 0.002 to 0.15.

[0024] Optionally, under the condition of x + y = 1, the upper limit of 2x / y is selected from 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7 or 6, and the lower limit is selected from 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 or 24.

[0025] Optionally, the size of the nanoscale high-silica Y zeolite is 10 to 50 nm.

[0026] Optionally, the size of the nanoscale high-silica Y zeolite is a range value determined by any two values among 10 nm, 50 nm and 100 nm or any one of them.

[0027] Optionally, M is Li, Na, K and / or Cs, preferably Na or K.

[0028] Optionally, T is selected from one of polydiallyldimethylammonium chloride, dimethyldiallylammonium chloride - acrylamide copolymer, polyquaternium - 11, polyquaternium - 39 and polyquaternium - 28.

[0029] Optionally, R1 and R2 are independently selected from at least one of the compounds shown in the structural formula of Formula II:

[0030] [NR4] a X q- Formula II

[0031] wherein R is selected from at least one of C1 - C8 alkyl and C1 - C8 alkoxy; X q- is selected from OH - , Cl - , Br - , I - , NO3 - , HSO4 - , SO4 2- , H2PO3 - , HPO3 2- and PO3 3- and at least one of them.

[0032] Optionally, R1 is selected from at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide.

[0033] Optionally, R2 is selected from at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium chloride, tetraethylammonium bromide, tetrapropylammonium chloride, tetrapropylammonium bromide, tetrabutylammonium chloride, and tetrabutylammonium bromide.

[0034] According to a second aspect of the present application, there is provided a method for preparing the above-mentioned nano-sized high-silica Y zeolite, the method comprising the following steps:

[0035] 1) Obtain an initial gel mixture A of raw materials containing an aluminum source Al 1 , a silicon source Si 1 , an alkali metal source M, a first organic template R1, and water;

[0036] Age the initial gel mixture A at a predetermined temperature for a predetermined time to obtain a directing agent A';

[0037] 2) Obtain an initial gel mixture B of raw materials containing the directing agent A' obtained in step 1), an aluminum source Al 2 , a silicon source Si 2 , an additional alkali metal source M, a molecular sieve growth inhibitor T, a second organic template R2, and water;

[0038] 3) Place the initial gel mixture B obtained in step 2) in a reaction kettle and crystallize at a predetermined temperature for a predetermined time;

[0039] 4) After the crystallization is completed, the solid product is separated, washed, and dried to obtain the nano-sized high-silica Y zeolite.

[0040] Optionally, step 2) includes: first obtaining a mixture B' of raw materials containing the directing agent A' obtained in step 1), an aluminum source Al 2 , a silicon source Si 2 , an alkali metal source M, an organic template R2, and water, and then adding a molecular sieve growth inhibitor T to the mixture B' and mixing evenly to obtain the initial gel mixture B.

[0041] Optionally, step 2) includes: obtaining the initial gel mixture B in the following order: mixing additional water with the alkali metal source M and the aluminum source Al 2 evenly and adding the organic template R2, then adding the silicon source Si 2 , and finally adding the directing agent A' obtained in step 1) to obtain a mixture B'; then adding a molecular sieve growth inhibitor T to the mixture B' and mixing evenly to obtain the initial gel mixture B.

[0042] Optionally, the method for preparing the nano-sized high-silica Y zeolite includes the following steps:

[0043] 1) Mix the raw materials containing aluminum source Al 1 , silicon source Si 1 , alkali metal source M, organic template R1 and water to obtain an initial gel mixture A; age the mixture A at a predetermined temperature for a predetermined time to obtain a directing agent A';

[0044] 2) Mix the raw materials containing aluminum source Al 2 , silicon source Si 2 , alkali metal source M, molecular sieve growth inhibitor T, organic template R2 and water to obtain an initial gel mixture;

[0045] 3) Add the directing agent A' obtained in step 1) to the initial gel mixture prepared in step 2) to obtain an initial gel mixture B, mix evenly and place it at a predetermined temperature for crystallization for a predetermined time;

[0046] 4) After the crystallization is completed, the solid product is separated, washed and dried to obtain the high-silica Y molecular sieve with a nanoscale structure.

[0047] The specific types of R1 and R2 used in this method are the same as described above, and the molecular sieve growth inhibitor T used is also the same as described above, which will not be elaborated here.

[0048] Optionally, after obtaining the initial gel mixture in step 2), stir for 0.5 to 4 hours, then add the directing agent A' and stir for 0.5 to 4 hours to obtain an initial gel mixture B.

[0049] Optionally, the molar amounts of the aluminum source in steps 1) and 2) are calculated as Al2O3; the molar amounts of the silicon source are calculated as SiO2; the molar amounts of the template R1 are calculated as the molar amounts of R1 itself; the molar amounts of the alkali metal source are calculated as the molar amounts of the corresponding metal oxide M2O of the corresponding alkali metal M; the molar amounts of the molecular sieve growth inhibitor T are calculated as the molar amounts of its corresponding monomer;

[0050] In step 1), the aluminum source Al 1 , silicon source Si 1 , alkali metal source M, organic template R1 and water have the following molar ratios:

[0051] SiO2 / Al2O3 = 5 to 30;

[0052] M2O / SiO2 = 0.01 to 0.5, where M is selected from at least one of the alkali metal elements;

[0053] R1 / SiO2 = 0.02 to 2;

[0054] H2O / SiO2 = 18 to 400.

[0055] Optionally, in step 2), the molar ratios of aluminum source Al 2 in the raw materials, silicon source Si 2 , alkali metal source M, molecular sieve growth inhibitor T, organic template R2 and water are as follows:

[0056] SiO2 / Al2O3 = 10 - 200;

[0057] M2O / SiO2 = 0.01 - 0.5, where M is selected from at least one of alkali metal elements;

[0058] R2 / SiO2 = 0.02 - 2;

[0059] T / SiO2 = 0.001 - 0.22;

[0060] H2O / SiO2 = 10 - 800;

[0061] The addition amount of the directing agent A' in step 1) makes the content of SiO2 in the directing agent A' in step 1) be 3 - 20 wt% of the content of SiO2 in the initial gel mixture B.

[0062] Optionally, in step 2), the molar ratios of aluminum source Al 2 in the raw materials, silicon source Si 2 , alkali metal source M, molecular sieve growth inhibitor T, organic template R2 and water are as follows:

[0063] SiO2 / Al2O3 = 10 - 200;

[0064] M2O / SiO2 = 0.01 - 0.3, where M is selected from at least one of alkali metal elements;

[0065] R2 / SiO2 = 0.02 - 1;

[0066] T / SiO2 = 0.002 - 0.15;

[0067] H2O / SiO2 = 10 - 500.

[0068] Optionally, in step 3), the addition amount of the structure-directing agent A' in step 1) is such that the percentage of the content of SiO2 in the structure-directing agent A' in step 1) relative to the content of SiO2 in the initial gel mixture B has an upper limit selected from 20 wt%, 19 wt%, 18 wt%, 17 wt%, 16 wt%, 15 wt%, 14 wt%, 13 wt%, 12 wt%, 11 wt%, 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, and a lower limit selected from 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%.

[0069] Optionally, the aluminum source Al in steps 1) and 2) 1 and Al 2 are independently selected from at least one of sodium aluminate, aluminum isopropoxide, γ-aluminum oxide, aluminum hydroxide, aluminum 2-butoxide, aluminum chloride, aluminum sulfate, sodium aluminate, aluminum nitrate, aluminum powder, and pseudo-boehmite.

[0070] Optionally, the silicon source Si in steps 1) and 2) 1 and Si 2 are independently selected from at least one of methyl orthosilicate, silica sol, tetraethyl orthosilicate, solid silica gel, sodium silicate, and white carbon black.

[0071] Optionally, the alkali metal source M in steps 1) and 2) is selected from at least one of lithium hydroxide, sodium hydroxide, potassium hydroxide, and cesium hydroxide.

[0072] Optionally, in step 1), the aging temperature is 25 to 140 °C and the aging time is 0.5 to 20 days.

[0073] Optionally, in step 1), the aging temperature is 30 to 120 °C and the aging time is 1 to 10 days.

[0074] Optionally, in step 3), the crystallization temperature is 80 to 170 °C and the crystallization time is 1 to 30 days.

[0075] Optionally, in step 3), the crystallization temperature is 90 to 140 °C and the crystallization time is 2 to 15 days.

[0076] Optionally, in step 1), the upper limit of the aging temperature is selected from 140 °C, 130 °C, 120 °C, 110 °C, 100 °C, 90 °C, 80 °C, 70 °C, 60 °C, 50 °C, 40 °C, 30 °C, and the lower limit is selected from 25 °C, 35 °C, 45 °C, 55 °C, 65 °C, 75 °C, 85 °C, 95 °C, 105 °C, 115 °C, 125 °C, 135 °C.

[0077] Optionally, in step 1), the upper limit of the aging time is selected from 20 days, 19 days, 18 days, 17 days, 16 days, 15 days, 14 days, 13 days, 12 days, 11 days, 10 days, 9 days, 8 days, 7 days, 6 days, 5 days, 4 days, 3 days, 2 days, and the lower limit is selected from 0.5 days, 1.5 days, 2.5 days, 3.5 days, 4.5 days, 5.5 days, 6.5 days, 7.5 days, 8.5 days, 9.5 days, 10.5 days, 11.5 days, 12.5 days, 13.5 days, 14.5 days, 15.5 days, 16.5 days, 17.5 days, 18.5 days, 19.5 days.

[0078] Optionally, in step 1), the aging is carried out in one of the ways of dynamic, static or a combination of dynamic and static.

[0079] In the present application, static aging means that the slurry in the reaction kettle is in a static state. Dynamic aging means that the slurry in the reaction kettle is in a non-static state, such as magnetic stirring or rotation.

[0080] Optionally, in step 3), the upper limit of the crystallization temperature is selected from 170 °C, 160 °C, 150 °C, 140 °C, 130 °C, 120 °C, 110 °C, 100 °C, 90 °C; the lower limit is selected from 80 °C, 85 °C, 95 °C, 105 °C, 115 °C, 125 °C, 135 °C, 145 °C, 155 °C, 165 °C.

[0081] Optionally, in step 3), the upper limit of the crystallization time is selected from 30 days, 29 days, 28 days, 27 days, 26 days, 25 days, 24 days, 23 days, 22 days, 21 days, 20 days, 19 days, 18 days, 17 days, 16 days, 15 days, 14 days, 13 days, 12 days, 11 days, 10 days, 9 days, 8 days, 7 days, 6 days, 5 days, 4 days, 3 days, 2 days, and the lower limit is selected from 1 day, 1.5 days, 2.5 days, 3.5 days, 4.5 days, 5.5 days, 6.5 days, 7.5 days, 8.5 days, 9.5 days, 10.5 days, 11.5 days, 12.5 days, 13.5 days, 14.5 days, 15.5 days, 16.5 days, 17.5 days, 18.5 days, 19.5 days, 20.5 days, 21.5 days, 22.5 days, 23.5 days, 24.5 days, 25.5 days, 26.5 days, 27.5 days, 28.5 days, 29.5 days.

[0082] Optionally, the crystallization in step 3) is carried out under autogenous pressure.

[0083] Optionally, the crystallization method in step 3) is carried out in a dynamic, static or a combination of dynamic and static manner.

[0084] In this application, static crystallization refers to the slurry in the reaction kettle being in a static state. Dynamic crystallization refers to the slurry in the reaction kettle being in a non-static state, such as magnetic stirring or rotation.

[0085] Optionally, the separation, washing, and drying described in step 4) are all conventional operations. Among them, the separation and washing can be carried out by centrifugation or filtration. Drying can be carried out by placing at 80 - 115 °C for 12 hours.

[0086] According to the third aspect of this application, a catalyst is provided, which contains at least one of the above-mentioned nanoscale high-silica Y zeolite and the nanoscale high-silica Y zeolite prepared according to the above method.

[0087] According to the fourth aspect of this application, the application of the above catalyst in catalytic cracking reaction is provided.

[0088] Optionally, the reaction conditions of the catalyst in the catalytic cracking reaction are: the reaction temperature is 160 - 350 °C, and the reaction time is 8 - 150 hours.

[0089] Optionally, the reaction time is the range value determined by any two values among 25 hours, 50 hours, 75 hours, 100 hours, and 150 hours and any value therein.

[0090] In this application, the term "silica-alumina ratio" means the molar ratio of silicon to aluminum in the zeolite calculated based on SiO2 and Al2O3, which has the same meaning as "2x / y" and "silica-alumina oxide ratio" in this application.

[0091] The beneficial effects that this application can produce include but are not limited to:

[0092] (1) This application provides a direct synthesis method for nanoscale high-silica Y zeolite, with a simple synthesis process and a fast crystallization rate.

[0093] (2) The nanoscale high-silica Y zeolite provided by this application has high crystallinity and purity; good thermal stability and hydrothermal stability; it can effectively alleviate the catalyst deactivation caused by diffusion limitation. It can be applied to fluid catalytic cracking, hydrocracking and other reactions.

[0094] (3) The nanoscale high-silica Y zeolite provided by this application has a simple preparation method and has practical value in the industrial production field. Description of the Drawings

[0095] Figure 1 is the X-ray diffraction (XRD) pattern of the synthesis product in Example Y1.

[0096] Figure 2 is the scanning electron micrograph (SEM) of the synthesis product in Example Y1.

[0097] Figure 3 It is the scanning electron microscope image (SEM) of the synthesis product of Comparative Example S8.

[0098] Figure 4 It is the scanning electron microscope image (SEM) of the synthesis product of Comparative Example S9.

[0099] Figure 5 It is the transmission electron microscope image (TEM) of the synthesis product of Example Y1.

[0100] Figure 6 It is the nitrogen physical adsorption and desorption isotherm (BET) of the synthesis product of Example Y1.

[0101] Figure 7 It is the comparison chart of the cumene cracking performance of Example Y1, Comparative Example S8 and commercial USY.

[0102] Figure 8 It is the comparison chart of the isopropylbenzene cracking performance of Example Y1, Comparative Example S8 and commercial USY.

[0103] Figure 9 It is the comparison chart of the thermal stability and hydrothermal stability of Example Y1 and commercial USY. Detailed Embodiments

[0104] The present invention will be further described below in conjunction with embodiments. It should be understood that these embodiments are only for illustration, but the present invention is not limited to these embodiments.

[0105] For the experimental methods without specific conditions in the following examples, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0106] Unless otherwise specified, the raw materials used in this application are all purchased through commercial channels and used directly without special treatment. Some raw material information is as follows:

[0107] Solid silica gel (analytical pure, Shanghai Chemical Reagent Company, China National Pharmaceutical Corporation); tetraethyl orthosilicate (analytical pure, Tianjin Kemiou Chemical Reagent Co., Ltd.); white carbon black (325 mesh, Shanghai Macklin Biochemical Co., Ltd.); silica sol (29% - 31% aqueous solution, Shanghai Macklin Biochemical Co., Ltd.); alumina (analytical pure, Shanghai Macklin Biochemical Co., Ltd.); aluminum nitrate (nonahydrate, analytical pure, Shanghai Macklin Biochemical Co., Ltd.); anhydrous aluminum chloride (analytical pure, Shanghai Macklin Biochemical Co., Ltd.); aluminum powder (99.9%, Shanghai Aladdin Biochemical Technology Co., Ltd.); aluminum isopropoxide (analytical pure, Shanghai Aladdin Biochemical Technology Co., Ltd.); sodium aluminate (analytical pure, Shanghai Aladdin Biochemical Technology Co., Ltd.); sodium hydroxide (analytical pure, Shanghai Aladdin Biochemical Technology Co., Ltd.); potassium hydroxide (analytical pure, Shanghai Aladdin Biochemical Technology Co., Ltd.); cesium hydroxide (analytical pure, Shanghai Aladdin Biochemical Technology Co., Ltd.); tetramethylammonium hydroxide (25 wt% aqueous solution, Anajie, Anhui Zesheng Technology Co., Ltd.); tetraethylammonium hydroxide (35 wt% aqueous solution, Shanghai Chemical Reagent Company, China National Pharmaceutical Corporation); tetrapropylammonium hydroxide (40 wt% aqueous solution, Anajie, Anhui Zesheng Technology Co., Ltd.); tetrabutylammonium hydroxide (40 wt% aqueous solution, Anajie, Anhui Zesheng Technology Co., Ltd.); tetramethylammonium bromide (analytical pure, Shanghai Aladdin Biochemical Technology Co., Ltd.); tetrapropylammonium chloride (97%, Shanghai Aladdin Biochemical Technology Co., Ltd.); tetrabutylammonium chloride (97%, Shanghai Aladdin Biochemical Technology Co., Ltd.); tetrabutylammonium bromide (analytical pure, Shanghai Aladdin Biochemical Technology Co., Ltd.); poly(diallyldimethylammonium chloride) (20 wt% aqueous solution, Shanghai Aladdin Biochemical Technology Co., Ltd.), dimethyldiallylammonium chloride - acrylamide copolymer (20 wt% aqueous solution, Shanghai Aladdin Biochemical Technology Co., Ltd.), polyquaternium - 11 (20 wt% aqueous solution, Shanghai Aladdin Biochemical Technology Co., Ltd.), polyquaternium - 39 (10 wt% aqueous solution, Shanghai Macklin Biochemical Co., Ltd.), polyquaternium - 28 (20 wt% aqueous solution, Shanghai Aladdin Biochemical Technology Co., Ltd.).

[0108] Unless otherwise specified, the test conditions of this application are as follows:

[0109] X - ray powder diffraction phase analysis (XRD) was performed using an X'Pert PRO X - ray diffractometer from PANalytical, Netherlands, with a Cu target, Kα radiation source (λ = 0.15418 nm), voltage 40 kV, and current 40 mA.

[0110] X-ray photoelectron spectroscopy was measured using a Thermofisher Escalab 250Xi+ in-situ X-ray photoelectron spectrometer from Thermo Fisher Scientific.

[0111] Scanning electron microscope (SEM) topography analysis was performed using a Hitachi SU8020 scanning electron microscope with an acceleration voltage of 2 kV.

[0112] Elemental composition was determined using a Magix 2424X X-ray fluorescence analyzer (XRF) from Philips.

[0113] Transmission electron microscope (TEM) was a JEM2100 transmission electron microscope from JEOL, Japan.

[0114] Physical adsorption was measured using an ASAP 2020 physical adsorption instrument from Micromeritics, USA, for the specific surface area and pore size distribution of the sample. Before analysis, the sample was pretreated by vacuum heating at 350 °C for 4 h, and the free volume of the sample tube was measured with helium as the medium. When analyzing the sample, nitrogen was used as the adsorption gas, and physical adsorption and desorption measurements were carried out at liquid nitrogen temperature (77 K). The BET equation was used to determine the specific surface area of the material; the total pore volume of the material was calculated using the nitrogen adsorption amount at a relative pressure (P / P0) of 0.99. The t-plot method was used to calculate the micropore surface area and micropore volume. The mesopore volume was obtained by subtracting the micropore volume from the total pore volume, and the external specific surface area was obtained by subtracting the micropore surface area from the total specific surface area. When calculating, the cross-sectional area of N2 molecules was taken as 0.162 nm 2 .

[0115] The present invention will be described in detail below through examples, but the present invention is not limited to these examples.

[0116] In the example ratio table, the addition amount of the directing agent is based on the mass ratio wt% of SiO2 in the directing agent to SiO2 in the initial gel, and the addition amount of the molecular sieve growth inhibitor is based on the molar ratio of the molecular sieve growth inhibitor monomer to SiO2, where poly(diallyldimethylammonium chloride) is based on the number of diallyldimethylammonium chloride monomers, dimethyldiallylammonium chloride acrylamide copolymer is based on the number of dimethyldiallylammonium chloride monomers, polyquaternium-11 is based on the number of N,N-dimethylaminomethyl acrylate (DMAEMA) cationic monomers, polyquaternium-28 is based on the number of dimethyldiallylammonium chloride monomers, and polyquaternium-39 is based on the number of dimethyldiallylammonium chloride monomers.

[0117] Example: D1-19

[0118] The directing agent ratio, aging temperature, aging method, and aging time of the directing agent D1-19 are shown in Table 1.

[0119] Preparation of the directing agent D1: Add 6.8 g of aluminum isopropoxide to 84.15 g of an aqueous solution of tetraethylammonium hydroxide, then add 0.133 g of sodium hydroxide, stir for 2 hours, then dropwise add 34.72 g of tetraethyl orthosilicate, and stir at room temperature for 2 h. Then transfer the solution to a sealed stainless steel autoclave, age statically at 50 °C for 0.5 days, and age statically at 100 °C for 2.5 days to obtain the required directing agent D1.

[0120] Table 1 Composition ratio, aging temperature, aging method, and aging time of the directing agent

[0121]

[0122] Si 1 O2: tetraethyl orthosilicate Si 2 O2: solid silica gel Si 3 O2: fumed silica Si 4 O2: silica sol

[0123] Al 1 2O3: aluminum isopropoxide Al 2 2O3: alumina Al 3 2O3: sodium aluminate Al 4 2O3: aluminum nitrate Al 5 2O3: aluminum chloride Al 6 2O3: aluminum powder

[0124] R1 1 : tetraethylammonium hydroxide R1 2 : tetrapropylammonium hydroxide R1 3 : tetramethylammonium hydroxide R1 4 : tetrabutylammonium hydroxide

[0125] M 1 2O: sodium hydroxide M 2 2O: potassium hydroxide M 3 2O: cesium hydroxide

[0126] Example Y1-34

[0127] Among them, the specific batching process of Example Y1 is as follows:

[0128] Mix 11.40 g of deionized water, 0.132 g of sodium hydroxide, and 0.307 g of sodium aluminate. Add 3.9 g of an aqueous solution of tetrabutylammonium hydroxide (40 wt%). After stirring evenly, add 1.8 g of solid silica gel. After stirring evenly, add 2.26 g of the above-prepared directing agent (so that the mass of SiO2 in the directing agent is 10 wt% of the mass of SiO2 in the mixed solution). After stirring at room temperature for 1 hour, add 2.7 g of a solution of polydiallyldimethylammonium chloride (10 wt%). Stir for another 4 hours, then transfer to a sealed high-pressure stainless-steel autoclave and crystallize dynamically at 120 °C under autogenous pressure for 6 days.

[0129] The specific batching processes of the remaining examples are similar to that of Example Y1, and the ratios are carried out according to Table 2. The addition amount of the directing agent is calculated based on the mass fraction of SiO2 in the directing agent to the mass of SiO2 in the initial gel.

[0130]

[0131]

[0132] Comparative Example S1-9

[0133] The specific batching process of Comparative Example S1-8 is similar to that of Example Y1, and the ratios are carried out according to Table 3. The addition amount of the directing agent is calculated based on the mass fraction of SiO2 in the directing agent to the mass of SiO2 in the initial gel.

[0134] The specific batching process of Comparative Example S9 is similar to that of Example Y1, except that the feeding order of S9 is deionized water, sodium hydroxide, sodium aluminate, aqueous solution of tetrabutylammonium hydroxide, solid silica gel, aqueous solution of polydiallyldimethylammonium chloride. After stirring at room temperature for 1 h, add the corresponding directing agent and then stir for 4 hours.

[0135] Table 3 Molecular sieve synthesis ratio, crystallization conditions, and obtained product structure

[0136]

[0137] Note: Si 1 O2: Tetraethyl orthosilicate Si 2 O2: Solid silica gel Si 3 O2: Fumed silica Si 4 O2: Silica sol

[0138] Al 1 2O3: Aluminum isopropoxide Al 2 2O3: Alumina Al 3 2O3: Sodium aluminate Al 4 2O3: Aluminum nitrate

[0139] R2 1 : Tetraethylammonium hydroxide R22 : Tetrapropylammonium hydroxide R2 3 : Tetramethylammonium hydroxide

[0140] M 1 2O: Sodium hydroxide M 2 2O: Potassium hydroxide M 3 2O: Cesium hydroxide

[0141] T 1 : Poly(diallyldimethylammonium chloride) T 2 : Dimethyldiallylammonium chloride-acrylamide copolymer

[0142] The XRD analysis was performed on the sample of Example Y1. The XRD diffraction pattern is as Figure 1 shown, presenting the characteristic peaks of the typical FAU topology structure. After calcining the Y1 sample at 600 °C for 4 h to remove the template agent, its specific surface area and pore volume were measured. The microporous specific surface area of the sample calculated by the t-plot method was 575 m 2 g -1 , the microporous pore volume was 0.28 cm 3 g -1 , the mesoporous pore volume was 0.24 cm 3 g -1 , and the external specific surface area was 159 m 2 g -1 .

[0143] The scanning electron microscope photograph of the obtained Y1 sample is as Figure 2 shown. It can be seen that the obtained sample is nanoscale in size, and its particle size is about 10 - 50 nm.

[0144] The scanning electron microscope photograph of the obtained Comparative Example S8 is as Figure 3 shown. It can be seen that the size of the obtained sample is about 100 - 400 nm. It shows that the addition of growth inhibitor T is a necessary condition for synthesizing nanoscale high-silica Y zeolite according to this application. Without the addition of the zeolite growth inhibitor, the size of the prepared sample is larger and uneven.

[0145] The scanning electron microscope photograph of the obtained Comparative Example S9 is as Figure 4 shown. It can be seen that the size of the obtained sample is a mixture of 10 - 50 nm and 100 - 400 nm. It indicates that the addition of the zeolite growth inhibitor at the end is a necessary condition for preparing nanoscale high-silica Y zeolite with uniform particle size. The particle size of the product obtained by adding the zeolite growth inhibitor before the directing agent is a mixture of 10 - 50 nm and 100 - 400 nm, and the particle size is uneven.

[0146] The transmission electron microscope photograph of the obtained Y1 sample is as Figure 5 shown. Obvious lattice fringes can be seen, proving that the small crystals of 10 - 50 nm have a crystal structure. CombiningFigure 1 From the XRD diffraction pattern, it can be known that it is nano Y zeolite.

[0147] The nitrogen physical adsorption and desorption isotherms of the obtained Y1 sample are as Figure 6 shown. It can be seen that the adsorption and desorption isotherms are of type I and type IV, and there is an H3-type hysteresis loop, indicating that the mesopores possessed are particle packing pores, namely intercrystalline mesopores. The nitrogen physical adsorption and desorption isotherms of samples Y2 - Y34 are similar to Figure 6 those, which are not attached again here. This shows that the Y-type zeolite prepared by this application has intercrystalline mesopores.

[0148] The samples obtained from Example Y1 and Comparative Example S8 were calcined according to the conventional method in the prior art to remove the template agent, and the ammonium-exchanged ammonium-type samples were calcined to obtain hydrogen-type catalysts. The hydrogen-type samples and commercial USY (oxide silica-alumina ratio of 10.7) samples were used in the catalytic cracking reaction of triisopropylbenzene. The specific experimental process and conditions are as follows: The samples were pressed and granulated, 50 mg of the 60 - 80 mesh sample was weighed, mixed with 0.5 g of 60 - 80 mesh quartz sand, and loaded into a fixed-bed reactor. It was activated with nitrogen at 500 °C for one hour, and then cooled to 160 °C to start the reaction. Triisopropylbenzene was carried by 150 mLmin -1 nitrogen passing through a triisopropylbenzene saturation bottle in an 80 °C water bath. The reaction tail gas was analyzed using an Agilent 7890A gas chromatograph from Agilent Technologies, PONA (100 m * 0.25 mm * 0.5 μm). The results are shown in Figure 7 shown. It can be seen that Example Y1 and Comparative Example S8 have better triisopropylbenzene conversion and lifespan than commercial USY (oxide silica-alumina ratio of 10.7), and the Y1 sample deactivates the slowest.

[0149] The above-obtained hydrogen-type Y1 and S8 samples and commercial USY samples were used in the catalytic cracking reaction of cumene. The specific experimental process and conditions are as follows: The samples were pressed and granulated, 50 mg of the 40 - 60 mesh sample was weighed, mixed with 0.5 g of 40 - 60 mesh quartz sand, and loaded into a fixed-bed reactor. It was activated with nitrogen at 500 °C for one hour, and then cooled to 350 °C to start the reaction. Cumene was carried by 100 mLmin -1 nitrogen passing through a cumene saturation bottle in a 60 °C water bath. The reaction tail gas was analyzed using an Agilent 7890A gas chromatograph from Agilent Technologies, PONA (100 m * 0.25 mm * 0.5 μm). The results are shown in Figure 8 shown. It can be seen that the initial activities of the three samples are close, but the Y1 sample has the slowest deactivation rate.

[0150] The samples Y1 and commercial USY were calcined in a muffle furnace at 900 °C in an air atmosphere for 6 hours, and the two zeolite samples were treated with saturated steam at 700 °C for 8 hours in a fixed-bed device. The retention rate of the micropore volume was measured by physical adsorption to compare the thermal stability and hydrothermal stability of the samples. The results are shown in Figure 9 . It can be seen that the sample of Example Y1 has better thermal stability and hydrothermal stability.

[0151] Using the XRD diffraction method, the samples obtained from Example Y1-34 and Comparative Example S1-9 were compared and analyzed. The results show that both Example Y1-34 and Comparative Example S8 are high-purity FAU samples, and Examples S1-7 are amorphous. Comparing with the sample Y1-34, it can be seen that in the synthesis of the nano-scale high-silica Y zeolite according to the present application, the addition of the seed agent is necessary; when preparing the seed agent, it is necessary to age the seed agent at a predetermined temperature; the crystallization process requires a predetermined temperature and cannot be crystallized at room temperature; the template agent R2, the alkali metal M 2 , the aluminum source Al 2 , and the silicon source Si 2 must also be added, and no crystallization can occur without adding any one of them.

[0152] The nitrogen physical adsorption results, XRF and XPS results of the obtained Y1, Y4, Y14, Y20, S8, S9, and USY are shown in Table 4. Comparing the physical adsorption results of S8 and Y1, it can be seen that when no growth inhibitor is added, the obtained product basically has no mesopores and the external specific surface area is also extremely low. Comparing the surface and bulk silicon-aluminum ratios of USY and Y1, Y4, Y14, and Y20, it can be seen that the aluminum distribution of the nano-scale high-silica Y zeolite prepared by this method is uniform.

[0153] Table 4 Structural properties of the products

[0154]

[0155]

[0156] The above are only several embodiments of the present application and do not impose any form of limitation on the present application. Although the present application is disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, making some changes or modifications using the technical content disclosed above is equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A nano-scale high-silica Y zeolite, characterized in that, The anhydrous chemical composition of the nanoscale high-silica Y zeolite is shown in Formula I: kM·mR1·nR2·pT·(Si x Al y )O2 formula I wherein M is selected from at least one of alkali metal elements; T represents a zeolite growth inhibitor; the zeolite growth inhibitor is selected from one of poly(diallyldimethylammonium chloride), dimethyldiallylammonium chloride-acrylamide copolymer, polyquaternium-11, polyquaternium-39, and polyquaternium-28; R1 represents a first organic template; R2 represents a second organic template, and R1 is different from R2; k represents the number of moles of alkali metal element corresponding to per mole of (Si x Al y )O2, where k = 0.01 to 0.20; m represents the number of moles of the organic templating agent R1 corresponding to per mole of (Si x Al y )O2, where m = 0.01 - 0.2; n represents the number of moles of the organic template agent R2 corresponding to each mole of (Si x Al y )O2, where n = 0.01 to 0.4; p represents the number of moles of the monomer of the molecular sieve growth inhibitor corresponding to per mole of (Si x Al y )O2, where p = 0.001 - 0.20; x and y respectively represent the molar fractions of Si and Al, 2x / y = 5 - 25, x + y = 1; The size of the nanoscale high-silica Y zeolite is 10 - 100 nm; The nanoscale high-silica Y zeolite has intercrystalline mesopores; R1 and R2 are independently selected from at least one of the compounds shown in the structural formula of Formula II; [NR4] q X q- Formula II Among them, R is selected from at least one of C1-C8 alkyl groups and C1-C8 alkoxy groups; X q- is selected from OH - , Cl - , Br - , I - , NO3 - , HSO4 - , SO4 2- , H2PO3 - , HPO3 2- and PO3 3- and at least one of them; The preparation method of the nanoscale high-silica Y zeolite comprises the following steps: 1) Obtain an initial gel mixture A of raw materials containing an aluminum source Al 1 , a silicon source Si 1 , an alkali metal source M, a first organic template R1, and water Age the initial gel mixture A at a predetermined temperature for a predetermined time to obtain a directing agent A'; 2) Obtain the initial gel mixture B of raw materials containing the guiding agent A' in step 1), aluminum source Al 2 , silicon source Si 2 , additional alkali metal source M, molecular sieve growth inhibitor T, second template agent R2 and water 3) Place the initial gel mixture B obtained in step 2) in a reaction kettle and crystallize at a predetermined temperature for a predetermined time; 4) After crystallization is completed, the solid product is separated, washed, and dried to obtain the nanoscale high-silica Y zeolite; The said step 2) includes: first obtaining a mixture B' of raw materials containing the directing agent A' of step 1), an aluminum source Al 2 , a silicon source Si 2 , an additional alkali metal source M, a second organic template agent R2 and water, and then adding a molecular sieve growth inhibitor T to the said mixture B' and mixing evenly to obtain the initial gel mixture B; In step 1), the aging temperature is 25 - 140 °C, and the aging time is 0.5 - 20 days; In step 3), the crystallization temperature is 80 - 170 °C, and the crystallization time is 1 - 30 days.

2. The nano-scale high-silica Y zeolite according to claim 1, characterized in that, The size of the nanoscale high-silica Y zeolite is 10 - 50 nm.

3. The nano-scale high-silica Y molecular sieve according to claim 1, wherein, M is selected from one of Li, Na, K, and Cs.

4. The nanoscale high-silica Y zeolite according to claim 1, wherein R1 is selected from at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide; R2 is selected from at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium chloride, tetraethylammonium bromide, tetrapropylammonium chloride, tetrapropylammonium bromide, tetrabutylammonium chloride, and tetrabutylammonium bromide.

5. The nano-scale high-silica Y zeolite according to claim 1, wherein In steps 1) and 2), the molar number of the aluminum source is calculated as Al2O3; the molar number of the silicon source is calculated as SiO2; the molar numbers of the first organic template R1 and the second organic template R2 are respectively calculated as the molar numbers of R1 and R2 themselves; the molar number of the alkali metal source is calculated as the molar number of the metal oxide M2O corresponding to the corresponding alkali metal M; the molar number of the zeolite growth inhibitor T is calculated as the molar number of its corresponding monomer; In step 1), the molar ratio of aluminum source Al 1 , silicon source Si 1 , alkali metal source M, first organic template R1 and water is as follows: SiO2 / Al2O3 = 5 - 30; M2O / SiO2 = 0.01 - 0.5, wherein M is selected from at least one of alkali metal elements; R1 / SiO2 = 0.02 - 2; H2O / SiO2 = 18 - 400.

6. The nano-scale high-silica Y zeolite according to claim 5, characterized in that, In step 2), the aluminum source Al in the raw materials 2 , the silicon source Si 2 , the additional alkali metal source M, the molecular sieve growth inhibitor T, the second organic template R2 and water have the following molar ratios: SiO2 / Al2O3 = 10 - 200; M2O / SiO2 = 0.01 - 0.5, wherein M is selected from at least one of alkali metal elements; R2 / SiO2 = 0.02 - 2; T / SiO2 = 0.001 - 0.22; H2O / SiO2 = 10 - 800; The addition amount of the directing agent A' in step 1) is such that the content of SiO2 in the directing agent A' in step 1) is 3 to 20 wt% of the SiO2 content in the initial gel mixture B.

7. The nano-scale high-silica Y zeolite according to claim 1, wherein, The aluminum sources Al described in step 1) and step 2) 1 and Al 2 are independently selected from at least one of sodium aluminate, aluminum isopropoxide, γ-aluminum oxide, aluminum hydroxide, aluminum 2-butoxide, aluminum chloride, aluminum sulfate, sodium aluminate, aluminum nitrate, aluminum powder, and pseudoboehmite; The silicon sources Si described in step 1) and step 2) 1 and Si 2 are independently selected from at least one of methyl orthosilicate, silica sol, tetraethyl orthosilicate, solid silica gel, sodium silicate and silica white; The alkali metal source M described in step 1) and step 2) is selected from at least one of lithium hydroxide, sodium hydroxide, potassium hydroxide, and cesium hydroxide.

8. The nano-scale high-silica Y zeolite according to claim 1, wherein In step 1), the aging temperature is 30 to 120 °C and the aging time is 1 to 10 days; In step 3), the crystallization temperature is 90 to 140 °C and the crystallization time is 2 to 15 days.

9. A catalyst, characterized in that, The catalyst comprises at least one of the nanoscale high-silica Y zeolites according to any one of claims 1 to 8.

10. Use of the catalyst according to claim 9 in the catalytic cracking reaction of triisopropylbenzene and the catalytic cracking reaction of cumene.

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