Mesopore-rich Y-type molecular sieve and preparation method thereof

Abstract

The invention relates to a Y-type molecular sieve rich in mesopores and a preparation method thereof, the method comprises acid exchange treatment, first hydrothermal roasting treatment, first ammonium exchange treatment, second hydrothermal roasting treatment, alkali treatment, first-stage aluminum adding treatment, second-stage aluminum adding treatment, second ammonium exchange treatment and urea modification treatment, the temperature of the first-stage aluminizing treatment is higher than that of the second-stage aluminizing treatment. By adopting the method disclosed by the invention, the mesoporous distribution can be effectively adjusted on the premise of ensuring the integrity of the molecular sieve crystal structure and the mesoporous channel structure, and the prepared molecular sieve has good acid resistance and is easy to store.

Description

Technical Field

[0001] The present disclosure relates to the field of molecular sieve preparation, and in particular, to a mesoporous Y-type molecular sieve and a preparation method thereof. Background Art

[0002] Molecular sieves are widely used in catalysis, adsorption and separation due to their shape selectivity, high specific surface area and strong acidity. Since their first use in the 1960s, Y molecular sieves (HY, REY, USY) have been the main active components of catalytic cracking and hydrocracking catalysts. However, with the increasing heaviness of crude oil, the content of polycyclic compounds in the raw materials has increased significantly, while their diffusion capacity in the molecular sieve pores has decreased significantly. As the main cracking member, the pore size of Y molecular sieve is only 0.74nm. When used to process heavy fractions such as residual oil, the accessibility of the catalyst active center will become the main obstacle to the cracking of the polycyclic compounds (such as polycyclic aromatic hydrocarbons and polycyclic cycloalkanes) contained therein; the presence of acidity on the surface of the molecular sieve causes the heavy oil molecules that cannot enter the pores to react non-selectively on the outer surface of the molecular sieve, affecting the product distribution.

[0003] In order to overcome the weaknesses of microporous materials, such as small pore size and high acidity on the surface, the synthesis of catalytic materials with silicon-rich and mesoporous surfaces has received increasing attention.

[0004] US Patents US5069890 and US5087348 disclose a method for preparing a mesoporous Y molecular sieve, the main process of which is: using commercially available USY as raw material, treating it at 760°C for 24 hours in an atmosphere of 100% water vapor. The mesoporous volume of the Y molecular sieve obtained by this method increases from 0.02mL / g to 0.14mL / g, but the crystallinity decreases from 100% to 70%, and the specific surface area increases from 683m 2 / g is reduced to 456m 2 / g, and the acid density dropped from 28.9% to 6%.

[0005] In the method for preparing mesoporous Y molecular sieve disclosed in U.S. Patent US5601798, HY or USY is used as raw material, mixed with NH4NO3 solution or a mixed solution of NH4NO3 and HNO3 in an autoclave, and treated at a temperature of 115-250°C for 2h-20h. The mesoporous volume of the obtained Y molecular sieve can reach 0.2mL / g-0.6mL / g, but the crystallinity and specific surface area are significantly reduced.

[0006] Chinese patent CN101722022 discloses a method for modifying a Y molecular sieve by alkali treatment, comprising slurrying and mixing the Y molecular sieve and a strong alkali aqueous solution in a mass ratio of molecular sieve (dry basis): strong alkali: distilled water = (0.1-2): (0.05-2): (4-15), and subjecting the mixture to alkali treatment at 0-120°C for 0.1-24h. The obtained molecular sieve has a higher N2 adsorption capacity than the parent Y molecular sieve.

[0007] Chinese patent CN 101723399 discloses a method for preparing a framework silicon-rich Y molecular sieve, which first uses an alkali solution to pre-treat the NaY molecular sieve for desiliconization, and then performs ammonium exchange and dealumination and siliconization treatment on the molecular sieve after alkali treatment. The mesopores of the obtained Y molecular sieve are increased, but not significantly.

[0008] Chinese patent CN103172082 discloses a method for preparing a mesoporous Y molecular sieve, which firstly performs ammonium exchange on the sodium-type Y molecular sieve, then treats it with an organic acid aqueous solution, treats the acid-treated molecular sieve with NaOH, and finally treats it with an ammonium nitrate aqueous solution to obtain a mesoporous Y molecular sieve. The obtained Y molecular sieve contains abundant micropores, and the mesopore volume can reach 0.5mL / g-1.5mL / g.

[0009] Chinese patent CN104760973 discloses a Y molecular sieve with ultra-high mesoporous content and its preparation method, first pre-treating Y-type zeolite at 300-600℃ for 1-5h; cooling to 200-600℃; in an anhydrous dry environment, introducing dry gas saturated with dealuminized silicon into the pre-treated Y-type zeolite, reacting for 0.5-7h to obtain a crude product; or in an anhydrous dry environment, while uniformly heating the temperature to 250-700℃, introducing dry gas saturated with dealuminized silicon into the pre-treated Y-type zeolite, reacting for 0.5-7h to obtain a crude product; the crude product is acid-treated; the acid-treated crude product is alkali-treated to obtain a Y molecular sieve. The Y molecular sieve obtained by this method has an ultra-high mesoporous content, but a low micropore volume. Summary of the invention

[0010] The purpose of the present disclosure is to provide a mesoporous Y-type molecular sieve and a preparation method thereof.

[0011] In order to achieve the above object, the present disclosure provides a method for preparing a mesoporous Y-type molecular sieve in a first aspect, the method comprising the following steps:

[0012] a. subjecting the NaY molecular sieve to an acid exchange treatment to obtain a first product, wherein the pH value of the acid exchange treatment is 2.5-3.5;

[0013] b. subjecting the first product to a first hydrothermal roasting treatment to obtain a second product;

[0014] c. subjecting the second product to a first ammonium exchange treatment to obtain a third product;

[0015] Based on the dry weight of the third product, the content of Na2O in the third product is less than 3 weight %;

[0016] d. subjecting the third product to a second hydrothermal roasting treatment to obtain a fourth product;

[0017] e. contacting the fourth product, alkali and water, and performing alkali treatment to obtain a mixed slurry containing a fifth product;

[0018] f. contacting the aluminum-containing compound with the mixed slurry, and sequentially performing a first stage aluminum addition treatment and a second stage aluminum addition treatment;

[0019] g. subjecting the sixth product obtained in step f to a second ammonium exchange treatment to obtain a seventh product;

[0020] h. subjecting the seventh product to urea modification treatment;

[0021] The temperature of the first aluminum addition treatment is higher than the temperature of the second aluminum addition treatment.

[0022] Optionally, step a comprises: contacting the NaY molecular sieve with an acidic solution, performing the acid exchange treatment, and then performing solid-liquid separation, washing and drying treatment on the obtained mixture to obtain the first product;

[0023] The acidic solution includes one or more of sulfuric acid solution, nitric acid solution, hydrochloric acid solution, citric acid solution, oxalic acid solution and tartaric acid solution;

[0024] The conditions of the acid exchange treatment include: temperature of 30-80°C, preferably 35-70°C; time of 0.5-2h, preferably 0.5-1h;

[0025] The silicon-aluminum ratio of the NaY molecular sieve is 4.8-5.0, and the crystallinity is above 80%. The silicon-aluminum ratio is the molar ratio of SiO2 to Al2O3 in the NaY molecular sieve;

[0026] The pH value of the acid exchange treatment is 2.8-3.1.

[0027] Optionally, in step b, the conditions of the first hydrothermal calcination treatment include: a treatment atmosphere of 100% water vapor atmosphere, a temperature of 500-600° C., and a time of 1-3 h.

[0028] Optionally, the first ammonium exchange treatment comprises: contacting the second product with an aqueous solution containing an ammonium salt to perform the first ammonium exchange treatment;

[0029] The weight ratio of the ammonium salt to the second product on a dry basis is 1:(0.1-1);

[0030] The conditions of the first ammonium exchange treatment include: time of 0.5-8h, temperature of 25-100°C;

[0031] The second ammonium exchange treatment comprises: contacting the sixth product with an aqueous solution containing an ammonium salt to perform the second ammonium exchange treatment;

[0032] The weight ratio of the ammonium salt to the sixth product on a dry basis is 1:(0.1-1);

[0033] The conditions of the second ammonium exchange treatment include: time of 0.5-8h, temperature of 25-100°C;

[0034] The ammonium salt includes one or more of ammonium chloride, ammonium sulfate and ammonium nitrate.

[0035] Optionally, in step d, the conditions of the second hydrothermal roasting treatment include: the treatment atmosphere is 100% water vapor atmosphere, the temperature is 550-750° C., preferably 600-700° C.; the time is 0.5-4 h, preferably 1-2.5 h.

[0036] Optionally, in step e, the base comprises an inorganic base, preferably one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide and ammonia water;

[0037] The weight ratio of the fourth product to the base on a dry basis is 1:(0.02-0.5), preferably 1:(0.05-0.4);

[0038] The conditions of the alkali treatment include: time of 0.5-6h and temperature of 25-100°C.

[0039] Optionally, in step f, the aluminum-containing compound includes one or more of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate and sodium aluminate;

[0040] The weight ratio of the fifth product calculated on a dry basis to the aluminum-containing compound calculated on an Al2O3 basis is 1:(0.03-0.3), preferably 1:(0.035-0.28);

[0041] The conditions of the first stage of aluminum addition treatment include: time of 0.5-3h, temperature of 70-100°C;

[0042] The conditions of the second stage of aluminum addition treatment include: time of 0.5-2h, temperature of 30-60°C.

[0043] Optionally, in step h, the urea modification treatment comprises: contacting the seventh product and urea with water, and drying the obtained solid product;

[0044] The weight ratio of the seventh product to the urea on a dry basis is 1:(0.02-0.3);

[0045] The contact conditions include: time of 0.1-12h, temperature of 25-100°C;

[0046] The drying conditions include: time of 0.5-10 hours and temperature of 50-105°C.

[0047] The second aspect of the present disclosure is a mesoporous Y-type molecular sieve prepared by the method described in the first aspect of the present disclosure.

[0048] Optionally, the unit cell parameter of the mesoporous Y-type molecular sieve is 24.35-24.55 angstroms, the relative crystallinity is more than 55%, and the specific surface area of ​​the mesopores is 250-400m 2 / g;

[0049] The mesopore-rich Y-type molecular sieve has mesopores with pore diameters in the ranges of 3-4.5 nm, 5.5-11.0 nm and 12.5-36 nm.

[0050] Optionally, the unit cell parameter of the Y-type molecular sieve is 24.40-24.52 angstroms, and the specific surface area of ​​the mesopores is 270-350 m 2 / g, and the relative crystallinity is 56-70%.

[0051] Optionally, the total volume of mesopores with pore sizes in the range of 3-4.5 nm is 0.038-0.045 cm 3 / g, and the total volume of mesopores with pore diameters ranging from 5.5 to 11.0 nm is 0.015 to 0.020 cm 3 / g, and the total volume of mesopores with pore diameters ranging from 12.5 to 36 nm is 0.350 to 0.410 cm 3 / g;

[0052] The total volume of the micropores is 0.180-0.300 cm 3 / g, and the total volume of the mesopores is 0.403-0.475cm 3 / g, with a total pore volume of 0.583-0.775 cm 3 / g, total specific surface area is 700-800m 2 / g;

[0053] The total volume of mesopores accounts for 53-70% of the total pore volume.

[0054] Through the above technical scheme, the present invention prepares a mesoporous Y-type molecular sieve by subjecting the NaY molecular sieve to acid exchange, secondary ammonium exchange, secondary hydrothermal roasting, alkali treatment, two-stage aluminum addition treatment and urea modification treatment. The method disclosed in the present invention can effectively adjust the mesopore distribution while ensuring the integrity of the molecular sieve crystal structure and the mesoporous channel structure. The prepared molecular sieve has good acid resistance and is easy to store.

[0055] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0057] Figure 1 This is the pore size distribution diagram of the Y-type molecular sieve A prepared in Example 1 of the present disclosure.

[0058] Figure 2 It is the pore size distribution diagram of the Y-type molecular sieve DB1 prepared in Comparative Example 1 of the present disclosure. DETAILED DESCRIPTION

[0059] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0060] The first aspect of the present disclosure provides a method for preparing a mesoporous Y-type molecular sieve, the method comprising the following steps:

[0061] a. subjecting the NaY molecular sieve to an acid exchange treatment to obtain a first product, wherein the pH value of the acid exchange treatment is 2.5-3.5;

[0062] b. subjecting the first product to a first hydrothermal roasting treatment to obtain a second product;

[0063] c. subjecting the second product to a first ammonium exchange treatment to obtain a third product;

[0064] Based on the dry weight of the third product, the content of Na2O in the third product is less than 3 weight %;

[0065] d. subjecting the third product to a second hydrothermal roasting treatment to obtain a fourth product;

[0066] e. contacting the fourth product, alkali and water, and performing alkali treatment to obtain a mixed slurry containing a fifth product;

[0067] f. contacting the aluminum-containing compound with the mixed slurry, and sequentially performing a first stage aluminum addition treatment and a second stage aluminum addition treatment;

[0068] g. subjecting the sixth product obtained in step f to a second ammonium exchange treatment to obtain a seventh product;

[0069] h. subjecting the seventh product to urea modification treatment;

[0070] The temperature of the first aluminum addition treatment is higher than the temperature of the second aluminum addition treatment.

[0071] In the present disclosure, "pH value of acid exchange treatment" refers to the pH value of the slurry obtained by contacting and mixing the NaY molecular sieve with the acidic solution, which is controlled by the amount of the acidic solution added.

[0072] In the present disclosure, the pH values ​​are all tested values ​​at room temperature (25° C.).

[0073] In the present disclosure, controlling the content of Na2O in the third product can make the prepared Y-type molecular sieve have a larger mesoporous specific surface area.

[0074] According to one embodiment of the present disclosure, the pH value of the acid exchange treatment is 2.8-3.1, and the above pH value range can improve the relative crystallinity of the Y-type molecular sieve.

[0075] According to one embodiment of the present disclosure, the silicon-aluminum ratio of the NaY molecular sieve is 4.8-5.0, the silicon-aluminum ratio is the molar ratio of SiO2 to Al2O3 in the NaY molecular sieve, and the crystallinity is above 80%.

[0076] According to one embodiment of the present disclosure, step a comprises: contacting the NaY molecular sieve with an acidic solution, performing an acid exchange treatment, and then performing solid-liquid separation, washing and drying treatment on the obtained mixture to obtain a first product. The acid exchange treatment in step a can promote the removal of skeleton aluminum in the subsequent preparation process of the Y-type molecular sieve, so that the prepared Y-type molecular sieve has a richer mesoporous structure; wherein the solid-liquid separation method is conventional in the art, for example, it can be centrifugal separation, filtration, etc.; the conditions for the drying treatment are conventional in the art and are not specifically required herein.

[0077] According to one embodiment of the present disclosure, the acidic solution is conventional in the art, for example, it may include one or more of sulfuric acid solution, nitric acid solution, hydrochloric acid solution, citric acid solution, oxalic acid solution and tartaric acid solution. The present disclosure does not specifically limit the concentration of the acidic solution.

[0078] According to one embodiment of the present disclosure, the conditions for the acid exchange treatment include: a temperature of 30-80°C, preferably 35-70°C; and a time of 0.5-2h, preferably 0.5-1h.

[0079] In the present disclosure, the hydrothermal calcination process is well known to those skilled in the art.

[0080] According to one embodiment of the present disclosure, in order to improve the thermal stability of Y-type molecular sieve, in step b, the conditions for the first hydrothermal calcination treatment include: the treatment atmosphere is 100% water vapor atmosphere, the temperature is 500-600°C, preferably 550-600°C; the time is 1-3h, preferably 1-2h.

[0081] According to one embodiment of the present disclosure, in step c, the first ammonium exchange treatment includes: contacting the second product with an aqueous solution containing an ammonium salt to perform a first ammonium exchange treatment; the present disclosure does not specifically limit the concentration of the aqueous solution containing the ammonium salt, and the ammonium salt includes one or more of ammonium sulfate, ammonium chloride and ammonium nitrate; the weight ratio of the ammonium salt to the second product calculated on a dry basis is (0.1-1):1; the conditions for the first ammonium exchange treatment include: time of 0.5-8h, temperature of 25-100°C.

[0082] According to one embodiment of the present disclosure, in order to improve the thermal stability of the Y-type molecular sieve, in step d, the conditions for the second hydrothermal roasting treatment include: the treatment atmosphere is 100% water vapor atmosphere, the temperature is 550-750°C, preferably 600-700°C, and more preferably 620-680°C; the time is 0.5-4h, preferably 1-2.5h.

[0083] According to one embodiment of the present disclosure, step e comprises: adding water to the fourth product for slurrying, contacting the obtained slurry with an alkali, and performing an alkali treatment to obtain a mixed slurry containing the fifth product. The present disclosure does not impose any specific restriction on the amount of water used, and the solid content of the slurry can be, for example, 10 weight %.

[0084] According to one embodiment of the present disclosure, in step e, the type of base is well known to those skilled in the art, for example, the base includes an inorganic base, preferably one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide and ammonia water.

[0085] According to one embodiment of the present disclosure, in step e, the weight ratio of the fourth product to the base on a dry basis is 1:(0.02-0.5), preferably 1:(0.05-0.4).

[0086] According to one embodiment of the present disclosure, in step e, the conditions for alkali treatment include: time of 0.5-6h and temperature of 25-100°C.

[0087] According to one embodiment of the present disclosure, in step f, the aluminum-containing compound includes one or more of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate and sodium aluminate.

[0088] According to one embodiment of the present disclosure, in step f, the weight ratio of the fifth product calculated on a dry basis to the aluminum-containing compound calculated on an Al2O3 basis is 1:(0.03-0.3), preferably 1:(0.035-0.28).

[0089] According to one embodiment of the present disclosure, the conditions for the first stage of aluminum addition treatment include: time 0.5-3h, preferably 0.8-2.8h; temperature 70-100°C, preferably 75-98°C; the conditions for the second stage of aluminum addition treatment include: time 0.5-2h, preferably 0.8-1.8h; temperature 30-60°C, preferably 32-58°C.

[0090] According to one embodiment of the present disclosure, in step g, the second ammonium exchange treatment includes: contacting the sixth product with an aqueous solution containing an ammonium salt to perform a second ammonium exchange treatment; the present disclosure does not specifically limit the concentration of the aqueous solution containing the ammonium salt, and the ammonium salt includes one or more of ammonium sulfate, ammonium chloride and ammonium nitrate; the weight ratio of the ammonium salt to the sixth product on a dry basis is (0.1-1):1; the conditions for the second ammonium exchange treatment include: time of 0.5-8h, temperature of 25-100°C.

[0091] In the present disclosure, washing is conventional in the art, for example, water washing, specifically, 5-10 times the weight of water can be used to rinse the solid.

[0092] According to one embodiment of the present disclosure, step c also includes: subjecting the mixture obtained from the first ammonium exchange treatment to solid-liquid separation, washing and drying to obtain a third product; wherein the drying method is conventional in the art and no specific requirements are made herein; the solid-liquid separation method is conventional in the art, for example, it may be centrifugal separation, filtration, etc.

[0093] According to one embodiment of the present disclosure, step g also includes: solid-liquid separation, washing and drying the mixture obtained by the second ammonium exchange treatment to obtain a seventh product; wherein the drying method is conventional in the art and no specific requirements are made herein; the solid-liquid separation method is conventional in the art, for example, it can be centrifugal separation, filtration, etc.

[0094] According to one embodiment of the present disclosure, in step h, the urea modification treatment includes: contacting the seventh product with a urea solution, and drying the obtained solid product; the weight ratio of the seventh product to urea on a dry basis is 1:(0.02-0.3); the contact conditions include: time is 0.1-12h, temperature is 25-100°C; the drying conditions include: time is 0.5-10h, temperature is 50-105°C; the drying method can be drying in a drying oven.

[0095] The second aspect of the present disclosure provides a mesoporous Y-type molecular sieve prepared by the method described in the first aspect of the present disclosure.

[0096] According to one embodiment of the present disclosure, the Y-type molecular sieve has mesopores with pore sizes ranging from 3-4.5 nm, 5.5-11.0 nm and 12.5-36 nm; the unit cell parameter of the Y-type molecular sieve is 24.35-24.55 angstroms, preferably 24.40-24.52 angstroms; the relative crystallinity is above 55%, preferably 56-70%; the specific surface area of ​​the mesopores is 250-400 m 2 / g; preferably 270-350m 2 / g.

[0097] In the present disclosure, "relative crystallinity" refers to the ratio of the crystallinity of the Y-type molecular sieve of the present disclosure to the crystallinity of the standard sample, which can be measured using the RIPP146-90 standard method. The standard sample is the NaY molecular sieve produced by Qilu Catalysis Company, and its crystallinity is positioned at 100%.

[0098] In the present disclosure, "unit cell parameter" refers to the maximum dimension of a single unit cell of the Y-type molecular sieve.

[0099] According to one embodiment of the present disclosure, the total volume of mesopores with a pore size in the range of 3-4.5 nm is 0.038-0.045 cm 3 / g, and the total volume of mesopores with pore diameters ranging from 5.5 to 11.0 nm is 0.015 to 0.020 cm 3 / g, and the total volume of mesopores with pore diameters ranging from 12.5 to 36 nm is 0.350 to 0.410 cm 3 / g

[0100] According to one embodiment of the present disclosure, the total volume of the micropores is 0.180-0.300 cm 3 / g, and the total volume of the mesopores is 0.403-0.475cm 3 / g, with a total pore volume of 0.583-0.775 cm 3 / g, total specific surface area is 700-800m 2 / g, and the total volume of mesopores accounts for 53-70% of the total pore volume.

[0101] The present disclosure will be further illustrated by examples below, but the present disclosure is not limited thereby. The instruments and reagents used in the examples of the present disclosure are all commonly used instruments and reagents by those skilled in the art unless otherwise specified.

[0102] The NaY molecular sieves in the examples and comparative examples were produced by the Qilu Branch of Catalyst Co., Ltd., and the unit cell parameters were The silicon-aluminum ratio is 4.8-5.0 and the crystallinity is 84.1%.

[0103] The unit cell parameters were determined using the RIPP145-90 standard method, which is described in Petrochemical Analysis Methods (RIPP Test Methods), edited by Yang Cuiding, Science Press, published in 1990.

[0104] The content of Na2O was determined using the GB / T30905-2014 standard method.

[0105] The relative crystallinity was measured using the RIPP146-90 standard method, which is described in Petrochemical Analysis Methods (RIPP Test Methods), edited by Yang Cuiding, published by Science Press in 1990.

[0106] The relative crystallinity of the present disclosure is crystallinity of examples / crystallinity of standard samples.

[0107] The standard sample used was NaY molecular sieve produced by Qilu Catalysis Company, and its crystallinity was set to 100%.

[0108] The method for determining the molecular sieve pore structure is as follows:

[0109] The AS-3 and AS-6 static nitrogen adsorption instruments produced by Quantachrome Instruments were used for determination.

[0110] Instrument parameters: The sample was placed in the sample handling system and vacuumed to 1.33×10 -2 Pa, keep the temperature and pressure for 4 hours to purify the sample. At the liquid nitrogen temperature of -196 ° C, the adsorption and desorption of nitrogen by the purified sample under different pressure ratios P / P0 were tested to obtain the N2 adsorption-desorption isotherm curve.

[0111] Then, the two-parameter BET formula was used to calculate the total specific surface area and mesopore specific surface area. The adsorption amount below the specific pressure P / P0=0.98 was taken as the total pore volume of the sample. The pore size distribution of the mesopore part was calculated using the BJH formula, and the integral method was used to calculate the total volume of micropores and the total volume of mesopores.

[0112] In the following Examples and Comparative Examples, the dry basis was measured by calcining the samples at 600° C. for 4 h.

[0113] Example 1

[0114] The Y-type molecular sieve A is prepared by the following steps:

[0115] a. Mixing NaY molecular sieve and hydrochloric acid solution to make pulp, the pH value of the pulp is 3.0, acid exchange treatment is carried out at 45° C. for 0.5 h, and the obtained mixture is filtered, washed and dried to obtain a first product;

[0116] The content of Na2O in the first product is less than 5 wt% based on the dry weight of the first product;

[0117] b. subjecting the first product to a first hydrothermal roasting treatment in a 100% water vapor atmosphere to obtain a second product;

[0118] The conditions of the first hydrothermal calcination treatment include: time of 2 h, temperature of 600°C;

[0119] c. 100 g of the second product on a dry basis was mixed with an ammonium chloride solution (the weight ratio of ammonium chloride to water was 1:10) and slurried, and subjected to a first ammonium exchange treatment to obtain a third product;

[0120] The conditions for the first ammonium exchange included: time of 1 h, temperature of 70°C;

[0121] Based on the dry weight of the third product, the content of Na2O in the third product is less than 3 weight %;

[0122] The weight ratio of ammonium chloride to the second product on a dry basis is 1:1;

[0123] d. subjecting the third product to a second hydrothermal roasting treatment in a 100% water vapor atmosphere to obtain a fourth product;

[0124] The conditions of the second hydrothermal calcination treatment include: time of 2.5 h, temperature of 620°C;

[0125] e. The fourth product is slurried with water to obtain a molecular sieve slurry with a solid content of 10 wt %; NaOH (purity 96 wt %) is mixed with the above molecular sieve slurry and subjected to alkali treatment to obtain a mixed slurry containing the fifth product;

[0126] The conditions of the alkali treatment include: time of 0.5 h, temperature of 50°C;

[0127] The weight ratio of the fourth product to sodium hydroxide on a dry basis is 1:0.17;

[0128] f. contacting Al2(SO4)3 with the mixed slurry, sequentially performing a first stage aluminum addition treatment and a second stage aluminum addition treatment, and then filtering and washing the mixture to obtain a sixth product;

[0129] The weight ratio of the fifth product calculated on a dry basis to the aluminum-containing compound calculated on alumina basis is 1:0.05;

[0130] The conditions of the first aluminum treatment included: time of 0.5 h and temperature of 75°C;

[0131] The conditions of the second aluminum treatment included: time of 1 h, temperature of 58°C;

[0132] g. mixing the sixth product obtained in step f with an ammonium sulfate solution, performing a second ammonium exchange treatment, and then filtering, washing and drying;

[0133] The weight ratio of solid product, ammonium sulfate and water on a dry basis is 1:1:10;

[0134] The conditions of the second ammonium exchange treatment include: time of 1 h, temperature of 70°C;

[0135] h. The seventh product obtained in step g and urea are contacted with water, and the obtained solid is dried in a drying oven to obtain a Y-type molecular sieve A, the parameters of which are listed in Table 1;

[0136] The conditions of the contact treatment included: time of 0.5 h, temperature of 35°C;

[0137] The conditions of the drying treatment include: time of 6 h and temperature of 75°C;

[0138] The weight ratio of urea to the seventh product on a dry basis is 0.03:1;

[0139] The pore size distribution of Y-type molecular sieve A is as follows Figure 1 As shown, in Figure 1 In the figure, A represents mesopores with a pore size in the range of 3.0-4.5 nm, B represents mesopores with a pore size in the range of 5.5-11.0 nm, and C represents mesopores with a pore size in the range of 12.5-36.0 nm.

[0140] Example 2

[0141] The Y-type molecular sieve B is prepared by the following steps:

[0142] a. Mixing NaY molecular sieve and nitric acid solution to make pulp, wherein the pH value of the pulp is 2.8, and subjecting the mixture to acid exchange treatment at 70° C. for 1 h. Filtering, washing and drying the obtained mixture to obtain a first product;

[0143] The content of Na2O in the first product is less than 5 wt% based on the dry weight of the first product;

[0144] b. subjecting the first product to a first hydrothermal roasting treatment in a 100% water vapor atmosphere to obtain a second product;

[0145] The conditions of the first hydrothermal calcination treatment include: time of 2 h, temperature of 600°C;

[0146] c. 100 g of the second product on a dry basis was mixed with an ammonium chloride solution (the weight ratio of ammonium chloride to water was 1:10) and slurried, and subjected to a first ammonium exchange treatment to obtain a third product;

[0147] The conditions for the first ammonium exchange included: time of 1 h, temperature of 70°C;

[0148] Based on the dry weight of the third product, the content of Na2O in the third product is less than 3 weight %;

[0149] The weight ratio of ammonium chloride to the second product on a dry basis is 1:1;

[0150] d. subjecting the third product to a second hydrothermal roasting treatment in a 100% water vapor atmosphere to obtain a fourth product;

[0151] The conditions of the second hydrothermal calcination treatment include: time of 1 h, temperature of 650°C;

[0152] e. The fourth product is slurried with water to obtain a molecular sieve slurry with a solid content of 10 wt %; NaOH (purity 96 wt %) is mixed with the above molecular sieve slurry and subjected to alkali treatment to obtain a mixed slurry containing the fifth product;

[0153] The conditions of the alkali treatment include: time of 0.5 h, temperature of 50°C;

[0154] The weight ratio of the fourth product to sodium hydroxide is 1:0.5 on a dry basis;

[0155] f. contacting AlCl3 with the mixed slurry, sequentially performing a first stage aluminum addition treatment and a second stage aluminum addition treatment, and then filtering and washing the mixture to obtain a solid product;

[0156] The weight ratio of the fifth product calculated on a dry basis to the aluminum-containing compound calculated on alumina basis is 1:0.29;

[0157] The conditions of the first aluminum treatment include: time of 3 h, temperature of 100 °C;

[0158] The conditions of the second aluminum treatment include: time of 0.5 h, temperature of 30°C;

[0159] g. mixing the sixth product obtained in step f with an ammonium chloride solution, performing a second ammonium exchange treatment, and then filtering, washing and drying;

[0160] The weight ratio of solid product, ammonium chloride and water on a dry basis is 1:1:10;

[0161] The conditions of the second ammonium exchange treatment include: time of 1 h, temperature of 70°C;

[0162] h. contacting the seventh product obtained in step g with urea and water, and drying the obtained solid in a drying oven to obtain a Y-type molecular sieve B, the parameters of which are listed in Table 1;

[0163] The conditions of the contact treatment included: time of 1 h, temperature of 40°C;

[0164] The conditions of drying treatment include: time 10 h, temperature 55°C;

[0165] The weight ratio of urea to the seventh product on a dry basis is 0.1:1.

[0166] Example 3

[0167] The Y-type molecular sieve C is prepared by the following steps:

[0168] a. Mixing NaY molecular sieve and sulfuric acid solution to make pulp, the pH value of the pulp is 2.6, acid exchange treatment is carried out at 60° C. for 1.5 h, and the obtained mixture is filtered, washed and dried to obtain a first product;

[0169] The content of Na2O in the first product is less than 5 wt% based on the dry weight of the first product;

[0170] b. subjecting the first product to a first hydrothermal roasting treatment in a 100% water vapor atmosphere to obtain a second product;

[0171] The conditions of the first hydrothermal calcination treatment include: time of 2 h, temperature of 600°C;

[0172] c. 100 g of the second product on a dry basis was mixed with an ammonium chloride solution (the weight ratio of ammonium chloride to water was 1:10) and slurried, and subjected to a first ammonium exchange treatment to obtain a third product;

[0173] The conditions for the first ammonium exchange included: time of 1 h, temperature of 70°C;

[0174] Based on the dry weight of the third product, the content of Na2O in the third product is less than 3 weight %;

[0175] The weight ratio of ammonium chloride to the second product on a dry basis is 1:1;

[0176] d. subjecting the third product to a second hydrothermal roasting treatment in a 100% water vapor atmosphere to obtain a fourth product;

[0177] The conditions of the second hydrothermal calcination treatment include: time of 1 h, temperature of 680°C;

[0178] e. The fourth product is slurried with water to obtain a molecular sieve slurry with a solid content of 10 wt %; NaOH (purity 96 wt %) is mixed with the above molecular sieve slurry and subjected to alkali treatment to obtain a mixed slurry containing the fifth product;

[0179] The conditions of the alkali treatment include: time of 0.5 h, temperature of 50°C;

[0180] The weight ratio of the fourth product to sodium hydroxide on a dry basis is 1:0.4;

[0181] f. contacting Al(NO3)3·9H2O with the mixed slurry, sequentially performing a first stage aluminum addition treatment and a second stage aluminum addition treatment, and then filtering and washing the mixture to obtain a solid product;

[0182] The weight ratio of the fifth product calculated on a dry basis to the aluminum-containing compound calculated on alumina basis is 1:0.14;

[0183] The conditions of the first aluminum treatment include: time of 1 h, temperature of 90°C;

[0184] The conditions of the second aluminum treatment include: time of 0.5 h, temperature of 50°C;

[0185] g. mixing the sixth product obtained in step f with an ammonium chloride solution, performing a second ammonium exchange treatment, and then filtering, washing and drying;

[0186] The weight ratio of solid product, ammonium chloride and water on a dry basis is 1:1:10;

[0187] The conditions of the second ammonium exchange treatment include: time of 1 h, temperature of 70°C;

[0188] h. The seventh product obtained in step g and urea are contacted with water, and the obtained solid is dried in a drying oven to obtain a Y-type molecular sieve C, whose parameters are listed in Table 1;

[0189] The conditions of the contact treatment included: time of 2 h, temperature of 25°C;

[0190] The conditions of the drying treatment include: time of 8 h and temperature of 100°C;

[0191] The weight ratio of urea to the seventh product on a dry basis is 0.25:1.

[0192] Comparative Example 1

[0193] The Y-type molecular sieve DB1 was prepared by the following steps:

[0194] a. Mixing NaY molecular sieve and ammonium chloride solution (the weight ratio of ammonium chloride to water is 1:10) and performing a first ammonium exchange treatment. Filtering, washing and drying the obtained mixture to obtain product a;

[0195] The conditions of the first ammonium exchange treatment include: time of 0.5 h, temperature of 45°C;

[0196] The weight ratio of ammonium chloride to NaY molecular sieve on a dry basis is 1:1;

[0197] Based on the dry weight of product a, the content of Na2O in product a is less than 5 weight %;

[0198] b. subjecting product a to a first hydrothermal calcination treatment in a 100% water vapor atmosphere to obtain product b;

[0199] The conditions of the first hydrothermal calcination treatment include: time of 1 h, temperature of 680°C;

[0200] c. mixing product b with an ammonium chloride solution and slurrying, performing a second ammonium exchange treatment, filtering, washing and drying the obtained mixture to obtain product c;

[0201] The conditions of the second ammonium exchange treatment include: time of 1 h, temperature of 70°C;

[0202] The weight ratio of product b, ammonium chloride and water on a dry basis is 1:1:10;

[0203] Based on the dry weight of the product b, the content of Na2O in the product b is less than 3 weight %;

[0204] d. subjecting product c to a second hydrothermal calcination in a 100% water vapor atmosphere to obtain product d;

[0205] The conditions of the second hydrothermal calcination treatment include: time of 2.5 h, temperature of 620°C;

[0206] e. 100 g of the product d on a dry basis was slurried with water to obtain a molecular sieve slurry with a solid content of 10 wt %; NaOH (purity 96 wt %) was mixed with the molecular sieve slurry, and the mixture was treated with alkali at 50° C. for 0.5 h, and the obtained mixture was filtered, washed and dried to obtain a product e;

[0207] f. The product e is mixed with an ammonium chloride solution and slurried, and a third ammonium exchange treatment is performed. The obtained mixture is filtered, washed and dried to obtain a Y-type molecular sieve DB1, whose parameters are listed in Table 1. The pore size distribution of the Y-type molecular sieve DB1 is shown in Figure 2 As shown;

[0208] The conditions of the third ammonium exchange treatment include: time of 1 h, temperature of 70°C;

[0209] The weight ratio of product e, ammonium chloride and water on a dry basis is 1:1:10.

[0210] Comparative Example 2

[0211] The Y-type molecular sieve DB2 was prepared by the following steps:

[0212] a. Mixing NaY molecular sieve and hydrochloric acid solution to make pulp, the pH value of the pulp is 4.0, acid exchange treatment is carried out at 45° C. for 0.5 h, and the obtained mixture is filtered, washed and dried to obtain product a;

[0213] Based on the dry weight of product a, the content of Na2O in product a is less than 5 weight %;

[0214] b. performing a first hydrothermal calcination treatment in a 100% water vapor atmosphere to obtain a product b;

[0215] The conditions of the first hydrothermal calcination treatment include: time of 2 h, temperature of 600°C;

[0216] c. Mix 100 g of the product b on a dry basis with an ammonium chloride solution (the weight ratio of ammonium chloride to water is 1:10) and perform a first ammonium exchange treatment. Filter, wash and dry the mixture to obtain a product c.

[0217] The conditions for the first ammonium exchange included: time of 1 h, temperature of 70°C;

[0218] Based on the dry weight of the product c, the content of Na2O in the product c is less than 3 weight %;

[0219] The weight ratio of ammonium chloride to product c on a dry basis is 1:1;

[0220] d. subjecting product c to a second hydrothermal calcination treatment in a 100% water vapor atmosphere to obtain product d;

[0221] The conditions of the second hydrothermal calcination treatment include: time of 1 h, temperature of 680°C;

[0222] e. 100 g of product d was slurried with water to obtain a molecular sieve slurry with a solid content of 10 wt %; NaOH (purity 96 wt %) was mixed with the above molecular sieve slurry and subjected to alkali treatment to obtain a mixed slurry containing product e;

[0223] The conditions of the alkali treatment include: time of 0.5 h, temperature of 50°C;

[0224] The weight ratio of product d to sodium hydroxide on a dry basis is 1:0.11;

[0225] f. contacting Al2(SO4)3 with the mixed slurry to perform aluminum addition treatment, and then filtering and washing the mixture to obtain a solid product;

[0226] The weight ratio of product e calculated on a dry basis to the aluminum-containing compound calculated on alumina basis is 1:0.05;

[0227] The conditions for aluminum addition treatment include: time 0.5 h, temperature 70°C;

[0228] g. The solid product obtained in step f is mixed with an ammonium chloride solution and slurried, subjected to a second ammonium exchange treatment, and then washed, filtered and dried to obtain a Y-type molecular sieve DB2, the parameters of which are listed in Table 1;

[0229] The weight ratio of solid product, ammonium chloride and water on a dry basis is 1:1:10;

[0230] The conditions of the second ammonium exchange treatment include: time of 1 hour and temperature of 70°C.

[0231] Comparative Example 3

[0232] The Y-type molecular sieve DB3 was prepared by the method of Example 1, except that in step a, the pH value of the slurry was 3.6. The parameters of the prepared Y-type molecular sieve DB3 are listed in Table 1.

[0233] Comparative Example 4

[0234] The Y-type molecular sieve DB4 was prepared by the method of Example 1, except that in step a, the pH value of the slurry was 2.2. The parameters of the prepared Y-type molecular sieve DB4 are listed in Table 1.

[0235] Comparative Example 5

[0236] The Y-type molecular sieve DB5 was prepared by the method of Example 1, except that:

[0237] Step f: contacting Al2(SO4)3 with the mixed slurry to perform aluminum addition treatment, and then filtering and washing the mixture to obtain a solid product;

[0238] The conditions for the aluminum addition treatment include: time of 1 hour and temperature of 75° C.; the parameters of the prepared Y-type molecular sieve DB5 are listed in Table 1.

[0239] Comparative Example 6

[0240] Y-type molecular sieve DB6 was prepared by the method of Example 1, except that in step b, the content of Na2O in the third product was 4.0 wt% based on the dry weight of the third product; the parameters of the prepared Y-type molecular sieve DB6 are listed in Table 1.

[0241] Table 1

[0242]

[0243]

[0244] according to Figure 1From the results, it can be seen that the Y-type molecular sieve A prepared in Example 1 has mesopores with pore sizes in the range of 3-4.5nm, 5.5-11.0nm and 12.5-36nm; the molecular sieves of Examples 2 and 3 were subjected to pore distribution tests, which had mesopores with pore sizes in the range of 3-4.5nm, 5.5-11.0nm and 12.5-36nm, indicating that the Y-type molecular sieve prepared by the method disclosed in the present invention has a good mesopore distribution.

[0245] According to the data in Table 1, the method disclosed in the present invention can effectively adjust the mesopore distribution while ensuring the integrity of the Y-type molecular sieve crystal structure and the mesopore channel structure.

[0246] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0247] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0248] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for preparing a mesoporous Y-type molecular sieve, characterized in that: The method comprises the following steps: a. subjecting the NaY molecular sieve to an acid exchange treatment to obtain a first product, wherein the pH value of the acid exchange treatment is 2.5-3.5; b. subjecting the first product to a first hydrothermal roasting treatment to obtain a second product; c. subjecting the second product to a first ammonium exchange treatment to obtain a third product; Based on the dry weight of the third product, the content of Na2O in the third product is less than 3 weight %; d. subjecting the third product to a second hydrothermal roasting treatment to obtain a fourth product; e. contacting the fourth product, alkali and water, and performing alkali treatment to obtain a mixed slurry containing a fifth product; f. contacting the aluminum-containing compound with the mixed slurry, and sequentially performing a first stage aluminum addition treatment and a second stage aluminum addition treatment; g. subjecting the sixth product obtained in step f to a second ammonium exchange treatment to obtain a seventh product; h. subjecting the seventh product to urea modification treatment; The temperature of the first aluminum addition treatment is higher than the temperature of the second aluminum addition treatment.

2. The method according to claim 1, wherein: Step a comprises: contacting the NaY molecular sieve with an acidic solution, performing the acid exchange treatment, and then performing solid-liquid separation, washing and drying treatment on the obtained mixture to obtain the first product; The acidic solution includes one or more of sulfuric acid solution, nitric acid solution, hydrochloric acid solution, citric acid solution, oxalic acid solution and tartaric acid solution; The conditions of the acid exchange treatment include: temperature of 30-80°C, preferably 35-70°C; time of 0.5-2h, preferably 0.5-1h; The silicon-aluminum ratio of the NaY molecular sieve is 4.8-5.0, and the crystallinity is above 80%. The silicon-aluminum ratio is the molar ratio of SiO2 to Al2O3 in the NaY molecular sieve; The pH value of the acid exchange treatment is 2.8-3.

1.

3. The method according to claim 1, wherein: In step b, the conditions of the first hydrothermal calcination treatment include: the treatment atmosphere is 100% water vapor atmosphere, the temperature is 500-600° C., and the time is 1-3 hours.

4. The method according to claim 1, wherein: The first ammonium exchange treatment comprises: contacting the second product with an aqueous solution containing an ammonium salt to perform the first ammonium exchange treatment; The weight ratio of the ammonium salt to the second product on a dry basis is 1:(0.1-1); The conditions of the first ammonium exchange treatment include: time of 0.5-8h, temperature of 25-100°C; The second ammonium exchange treatment comprises: contacting the sixth product with an aqueous solution containing an ammonium salt to perform the second ammonium exchange treatment; The weight ratio of the ammonium salt to the sixth product on a dry basis is 1:(0.1-1); The conditions of the second ammonium exchange treatment include: time of 0.5-8h, temperature of 25-100°C; The ammonium salt includes one or more of ammonium chloride, ammonium sulfate and ammonium nitrate.

5. The method according to claim 1, wherein: In step d, the conditions of the second hydrothermal roasting treatment include: the treatment atmosphere is 100% water vapor atmosphere, the temperature is 550-750° C., preferably 600-700° C.; the time is 0.5-4 h, preferably 1-2.5 h.

6. The method according to claim 1, wherein: In step e, the base includes an inorganic base, preferably one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide and ammonia water; The weight ratio of the fourth product to the base on a dry basis is 1:(0.02-0.5), preferably 1:(0.05-0.4); The conditions of the alkali treatment include: time of 0.5-6h and temperature of 25-100°C.

7. The method according to claim 1, wherein: In step f, the aluminum-containing compound includes one or more of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate and sodium aluminate; The weight ratio of the fifth product calculated on a dry basis to the aluminum-containing compound calculated on an Al2O3 basis is 1:(0.03-0.3), preferably 1:(0.035-0.28); The conditions of the first stage of aluminum addition treatment include: time of 0.5-3h, temperature of 70-100°C; The conditions of the second stage of aluminum addition treatment include: time of 0.5-2h, temperature of 30-60°C.

8. The method according to claim 1, wherein: In step h, the urea modification treatment comprises: contacting the seventh product, urea and water, and drying the obtained solid product; The weight ratio of the seventh product to the urea on a dry basis is 1:(0.02-0.3); The contact conditions include: time of 0.1-12h, temperature of 25-100°C; The drying conditions include: time of 0.5-10 hours and temperature of 50-105°C.

9. A mesoporous Y-type molecular sieve prepared by the method according to any one of claims 1 to 8.

10. The mesoporous Y-type molecular sieve according to claim 9, wherein: The unit cell parameter of the mesoporous Y-type molecular sieve is 24.35-24.55 angstroms, the relative crystallinity is more than 55%, and the specific surface area of ​​the mesopores is 250-400 m 2 / g; The mesopore-rich Y-type molecular sieve has mesopores with pore diameters in the ranges of 3-4.5 nm, 5.5-11.0 nm and 12.5-36 nm.

11. The mesoporous Y-type molecular sieve according to claim 10, wherein: The unit cell parameters of the Y-type molecular sieve are 24.40-24.52 angstroms, and the specific surface area of ​​the mesopores is 270-350 m 2 / g, and the relative crystallinity is 56-70%.

12. The mesoporous Y-type molecular sieve according to claim 10, wherein: The total volume of mesopores with pore sizes in the range of 3–4.5 nm is 0.038–0.045 cm 3 / g, and the total volume of mesopores with pore diameters ranging from 5.5 to 11.0 nm is 0.015 to 0.020 cm 3 / g, and the total volume of mesopores with pore diameters ranging from 12.5 to 36 nm is 0.350 to 0.410 cm 3 / g; The total volume of the micropores is 0.180-0.300 cm 3 / g, and the total volume of the mesopores is 0.403-0.475cm 3 / g, with a total pore volume of 0.583-0.775 cm 3 / g, total specific surface area is 700-800m 2 / g; The total volume of mesopores accounts for 53-70% of the total pore volume.

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