Mesoporous NaY molecular sieve gas phase ultra-stability and rare earth modification method and catalytic cracking catalyst

Abstract

The invention discloses a gas phase ultra-stability and rare earth modification method of a mesoporous NaY molecular sieve and a catalytic cracking catalyst.The modification method comprises the steps that a first silicon source, a first aluminum source, an alkali source and water are mixed and then aged, and a NaY molecular sieve structure directing agent is obtained; mixing a second silicon source, a second aluminum source, a NaY molecular sieve structure directing agent and a precursor of metal M with a defect structure promoting effect to obtain a precursor solution, and performing primary crystallization; and adding a third aluminum source into the precursor solution after the first crystallization, carrying out second crystallization to obtain a mesoporous NaY molecular sieve, drying, dehydrating and refining the mesoporous NaY molecular sieve, carrying out an ultra-stable reaction on the mesoporous NaY molecular sieve and SiCl4 to obtain a gas-phase ultra-stable mesoporous NaY molecule, and carrying out rare earth exchange to obtain the rare earth ultra-stable mesoporous Y molecular sieve. The molecular sieve obtained by the method has a large number of mesopores and a relatively high silica-alumina ratio, and the Y molecular sieve with relatively high rare earth content and relatively high mesopore content is obtained after rare earth modification.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of catalytic cracking catalysts, and particularly relates to a method for gas-phase ultrastabilization and rare earth modification of mesoporous NaY molecular sieves and a catalytic cracking catalyst. BACKGROUND

[0002] NaY molecular sieves are the main active components of catalytic cracking (FCC) catalysts. However, the microporous structure of ordinary NaY molecular sieves seriously hinders the diffusion of heavy oil macromolecules in the pores, resulting in poor accessibility of the acid active centers thereof, and it is necessary to introduce mesoporous structures into NaY molecular sieves to improve the cracking capacity of NaY molecular sieves for heavy and poor quality raw oil.

[0003] The preparation methods of ultrastable Y molecular sieves generally include hydrothermal ultrastabilization, liquid phase fluorine salt method and gas phase SiCl4 method (gas phase ultrastabilization method). The method of combining ammonium ion exchange and steam calcination (hydrothermal ultrastabilization method) is generally used in industry to prepare ultrastable Y molecular sieves (USY), which can improve the framework silica-alumina ratio of the molecular sieve while obtaining mesoporous structures. However, lattice collapse and structure damage may occur when de-alumination and silicon supplementation are performed under hydrothermal ultrastabilization conditions, and multiple ammonium ion exchanges are required in this process, which will generate a large amount of ammonia-nitrogen wastewater and result in high treatment cost. Although the liquid phase fluorine salt method can obtain ultrastable Y molecular sieves with good crystallinity, the use of fluorine ions in the ultrastabilization process will cause corrosion of the equipment, and therefore the method does not have industrial application value. The gas phase SiCl4 method (gas phase ultrastabilization method) reacts dehydrated NaY molecular sieves with SiCl4 at a certain temperature to remove framework aluminum and quickly complete silicon supplementation. This method can obtain ultrastable Y molecular sieves with high silica and high thermal stability, and the gas phase ultrastabilization method does not require repeated multiple ammonium ion exchanges and high temperature calcination.

[0004] In addition to ultrastabilization modification, REY molecular sieves obtained by rare earth ion and ammonium ion exchange modification can improve the stability and acid properties of Y molecular sieves, thereby improving the catalytic performance, and have become an indispensable component of catalytic cracking catalysts.

[0005] Patent CN1127161A discloses a preparation method of a rare earth-containing silicon-rich ultrastable Y-type molecular sieve, which is a method for completing the ultrastabilization of NaY and the ion exchange of rare earth ions in one step by using SiCl4 to perform gas phase de-alumination and silicon supplementation in the presence of solid RECl3, taking NaY as the raw material. The molecular sieve prepared according to the method has a unit cell constant of 2.430-2.460 nanometers, a rare earth content of 0.15-10.0wt%, a Na2O content of less than 1.0wt%, and has a relatively high crystalline retention degree, high thermal bearing capacity and hydrothermal stability. The defect of this technology is that the gas phase ultrastable molecular sieve obtained has fewer mesopores in the framework.

[0006] Patent CN1382525A discloses a method for preparing rare-earth high-silica Y-type zeolite. This method includes drying the rare-earth-containing Y-type zeolite to reduce its water content to below 10 wt%, then introducing silicon tetrachloride gas carried by dry air at a weight ratio of silicon tetrachloride to Y-zeolite of 0.1–0.9:1. The reaction is carried out at a temperature of 150–600°C for 10 minutes to 6 hours. After the reaction, the mixture is purged with dry air for 5 minutes to 2 hours. A drawback of this technique is that the resulting gas-phase ultrastable molecular sieve framework has relatively few mesopores.

[0007] Patent CN108455625A discloses a method for preparing modified Y-type molecular sieves. This method involves ion-exchange reaction of NaY molecular sieves with a rare earth solution to obtain a Y-type molecular sieve with a reduced sodium oxide content and conventional cell size containing rare earth elements. Then, it is calcined at 350–480°C under a 30–90% (v / v) water vapor atmosphere to obtain a Y-type molecular sieve with a reduced cell constant. Finally, the molecular sieve and the Y-type molecular sieve with reduced cell constant are reacted with silicon tetrachloride gas at a weight ratio of silicon tetrachloride:Y zeolite = 0.1–0.7:1 to obtain a modified molecular sieve. The drawback of this technique is that the resulting gas-phase ultrastable molecular sieve framework has relatively few mesopores. Summary of the Invention

[0008] The purpose of this invention is to provide a gas-phase ultrastable and rare-earth modified method for mesoporous NaY molecular sieves. The molecular sieve obtained by this method has a large number of mesopores and a high silicon-to-aluminum ratio. Starting from a gas-phase ultrastable mesoporous NaY molecular sieve, this invention modifies it through a process of water washing followed by ion exchange to obtain a Y molecular sieve with a high rare-earth content and a large number of mesopores.

[0009] Another objective of this invention is to provide a catalytic cracking catalyst.

[0010] To achieve the above objectives, this invention provides a method for gas-phase ultrastability and rare-earth modification of mesoporous NaY molecular sieves, comprising the following steps:

[0011] S1, after mixing and aging the first silicon source, the first aluminum source, the alkali source and water, NaY molecular sieve structure directing agent is obtained;

[0012] S2, the second silicon source, the second aluminum source, the NaY molecular sieve structure directing agent and the precursor of metal M with defect structure promoting effect are mixed to obtain a precursor solution, and the precursor solution is subjected to first crystallization at 60-80℃ for 1-28h.

[0013] S3, add a third aluminum source to the precursor solution after the first crystallization to obtain a metal aluminosilicate gel, and crystallize the obtained metal aluminosilicate gel a second time at 90-110℃ for 16-72h to obtain a mesoporous NaY molecular sieve. In the metal aluminosilicate gel, metal M is calculated as its oxide, silicon element is calculated as SiO2, and the molar ratio of metal M oxide to SiO2 is 0.07-0.10.

[0014] S4. After drying, dehydrating and refining the mesoporous NaY molecular sieve, it is reacted with SiCl4 at 200-500℃ for 30-60 min to obtain gas-phase ultrastable mesoporous NaY molecular sieve.

[0015] S5, the gas-phase ultrastable mesoporous NaY molecular sieve is mixed with deionized water, slurried, and rare earth solution is added for rare earth exchange to obtain rare earth ultrastable mesoporous Y molecular sieve.

[0016] The gas-phase ultrastable and rare earth modified method of mesoporous NaY molecular sieves of the present invention, wherein in step S1, the first silicon source, the first aluminum source, the alkali source and water are calculated as SiO2, Al2O3, Na2O and H2O respectively, and the molar ratio is (10-30):1:(10-30):(260-480).

[0017] The gas-phase ultrastable and rare-earth modified method of mesoporous NaY molecular sieves of the present invention, wherein the molar ratio of SiO2, Al2O3, Na2O and H2O in the metal aluminosilicate gel is (10-20):1:(2-10):(150-300).

[0018] The gas-phase ultrastability and rare earth modification method of mesoporous NaY molecular sieves described in this invention, wherein the first silicon source and the second silicon source are the same or different, and respectively include one or more of tetraethyl orthosilicate, silica sol, silica powder, silicic acid, fumed silica, and water glass.

[0019] The gas-phase ultrastability and rare earth modification method of mesoporous NaY molecular sieves described in this invention, wherein the first aluminum source, the second aluminum source, and the third aluminum source are the same or different, and respectively include one or more of the following: high-alkali sodium aluminate solution (high-alkali), low-alkali sodium aluminate solution (low-alkali), sodium aluminate, alumina, aluminum sulfate, aluminum isopropoxide, boehmite, aluminum chloride, aluminum citrate, aluminum hydroxide, and aluminum nitrate.

[0020] The gas-phase ultrastability and rare earth modification method of mesoporous NaY molecular sieves of the present invention, wherein the metal M is an alkaline earth metal, and the alkaline earth metal is one or more of Ca, Mg, Be, Ba and Sr.

[0021] The gas-phase ultrastable and rare-earth modified method of mesoporous NaY molecular sieves of the present invention includes the following steps: in step S1, the aging temperature is 30-50℃ and the aging time is 1-28h; in step S2, the precursor solution is mixed at 25-60℃; in step S3, the metal aluminosilicate gel is mixed at 25-80℃; the product obtained after secondary crystallization in step S3 is cooled, washed, filtered, and dried at 60-120℃ to obtain the mesoporous NaY molecular sieve.

[0022] In the gas-phase ultrastable and rare-earth modified method of mesoporous NaY molecular sieves described in this invention, the mass of Al2O3 in the NaY molecular sieve structure directing agent in step S3 accounts for 3-12% of the mass of Al2O3 in the metal aluminosilicate gel.

[0023] In the gas-phase ultrastable and rare-earth modified method of mesoporous NaY molecular sieve described in this invention, the mass ratio of SiCl4 to mesoporous NaY molecular sieve in step S4 is 0.2-0.5.

[0024] The gas-phase ultrastable and rare-earth modified method for mesoporous NaY molecular sieves of the present invention, in step S5, has a rare-earth solution concentration of 2-12 wt%, and the mass ratio of the rare-earth solution (calculated as rare-earth oxides) to the gas-phase ultrastable mesoporous NaY molecular sieve is 0.01-0.15. In step S5, during the pulping process, it is preferable to perform two pulping operations. First, the gas-phase ultrastable mesoporous NaY molecular sieve is mixed with deionized water at a mass ratio of 1:10 and pulped at 60-90℃ for 20-40 min. After filtration, the filter cake is mixed again with deionized water at a mass ratio of 1:10 and pulped again at 60-90℃ for 20-40 min to complete the pulping process.

[0025] The gas-phase ultrastable and rare earth modification method of mesoporous NaY molecular sieves of the present invention includes step S5, in which the pH value of the system is adjusted to 3.0-4.5, the ion exchange temperature is 60-90℃, the ion exchange time is 60-90min, and after the exchange, the system is filtered, washed, and dried.

[0026] To achieve the above objectives, the present invention also provides a catalytic cracking catalyst comprising a gas-phase ultrastable and rare-earth modified method for obtaining Y molecular sieves, which includes the mesoporous NaY molecular sieves described above.

[0027] Beneficial effects of this invention:

[0028] The method described in this invention achieves the sequential growth and detachment of alkaline earth metals within the molecular sieve framework through stepwise crystallization, thereby realizing the in-situ introduction of mesoporous structures within the crystals. In the first crystallization step, the relatively low temperature is unfavorable for Al ions to enter the molecular sieve framework, and the introduction of a separate aluminum source reduces the basicity of the system. The combined effect of these two factors facilitates the entry of alkaline earth metal ions into the molecular sieve framework. In the second crystallization step, the high temperature favors the entry of aluminum ions into the molecular sieve framework, and the subsequent addition of a strongly alkaline aluminum source increases the basicity of the system, making the MO bonds in the molecular sieve framework unstable and causing alkaline earth metal ions to detach from the framework. This results in structural defects in the crystals and promotes the formation of numerous mesopores. Because the mesopores are generated in situ during this synthesis process, unlike the post-processing method, the mesopores produced by this method are more stable. The mesoporous NaY molecular sieve prepared by this invention, after gas-phase ultrastabilization treatment, exhibits a higher mesopore content than ordinary NaY molecular sieves after the same treatment; moreover, the molecular sieve obtained after gas-phase ultrastabilization treatment has a higher rare earth content after rare earth exchange. Attached Figure Description

[0029] Figure 1 XRD patterns of NaY molecular sieves before ion exchange provided in Comparative Example 1, Comparative Example 2, Example 1, Example 2, Example 3, Example 4 and Example 5.

[0030] Figure 2A Nitrogen adsorption-desorption isotherms of NaY-type molecular sieves after ion exchange, provided for Comparative Example 1 and Example 4.

[0031] Figure 2B The diagram shows the pore size distribution of the NaY-type molecular sieves after ion exchange, as provided in Comparative Example 1 and Example 4. Detailed Implementation

[0032] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0033] In the examples, the water glass, high-alkali sodium aluminate, low-alkali sodium aluminate, and aluminum sulfate were sourced from Lanzhou Petrochemical Company of China National Petroleum Corporation and were industrial products; the remaining raw materials were commercially available and were of analytical grade.

[0034] The mesoporous NaY molecular sieves provided in the examples were tested using the following analytical instruments:

[0035] 1. Phase analysis and confirmation were performed using a Shimadzu XRD-7000 X-ray crystal powder diffractometer. Instrument parameters: Cu-Ka rays, wavelength 0.1543 nm, tube voltage 40 kV, tube current 30 mA. Sample testing conditions: scanning angle 5°–40°, scanning speed 8° / min.

[0036] 2. The adsorption-desorption isotherms of the samples were determined at liquid nitrogen temperature using an ASAP2020M fully automated adsorption instrument manufactured by Micromeritics, USA. Nitrogen gas was used as the adsorbate. The T-plot model was used to distinguish the internal and external surface areas of the samples. The pore volume and pore size distribution were determined by the static volumetric method, thereby calculating the pore structure parameters.

[0037] The following are the specific implementation methods.

[0038] The preparation process of the NaY molecular sieve structure directing agent used in the examples and comparative examples is as follows:

[0039] The silicon sources used in preparing the molecular sieves of the structure-directing agents and examples / comparative examples were water glass (with technical specifications of 6.89 wt% Na2O, 19.81 wt% SiO2, and 73.30 wt% H2O) and silica sol (with technical specifications of 40 wt% SiO2 and 60 wt% H2O). The aluminum and alkali sources were high-alkali sodium aluminate (with technical specifications of 21.13 wt% Na2O, 3.10 wt% Al2O3, and 75.77 wt% H2O) and low-alkali sodium aluminate (with technical specifications of 11.98 wt% Na2O, 8.07 wt% Al2O3, and 79.95 wt% H2O), and the purity of aluminum sulfate octadechydrate was 99 wt%. The alkali source was NaOH.

[0040] (1) NaY molecular sieve structure directing agent was prepared according to the molar ratio of Na2O:Al2O3:SiO2:H2O=12:1:10:260. 126.20g of water glass and 137.31g of high-alkali sodium aluminate were stirred evenly at room temperature and aged at 35℃ for 8h to obtain white gel-like NaY molecular sieve structure directing agent (1).

[0041] (2) Prepare NaY molecular sieve structure directing agent according to the molar ratio of Na2O:Al2O3:SiO2:H2O=16:1:15:320. Stir 151.44g of water glass and 109.85g of high-alkali sodium aluminate at room temperature, and age at 50℃ for 12h to obtain white gel-like NaY molecular sieve structure directing agent (2).

[0042] (3) Prepare NaY molecular sieve structure directing agent according to the molar ratio of Na2O:Al2O3:SiO2:H2O=30:1:28:480. Stir 227.15g of water glass and 88.27g of high-alkali sodium aluminate at room temperature, and age at 45℃ for 16h to obtain white gel-like NaY molecular sieve structure directing agent (3).

[0043] The following examples provide a method for preparing gas-phase ultrastable and rare-earth modified mesoporous NaY molecular sieves:

[0044] Example 1

[0045] (1) Step 1: Dissolve 9.46g of aluminum sulfate octadechydrate in 11.91g of deionized water to obtain an aluminum sulfate solution. Add 2.98g of beryllium sulfate tetrahydrate and the above aluminum sulfate solution to 47.95g of water glass. After vigorous stirring, add 15.27g of directing agent (1). Stir evenly at 40°C and crystallize at 60°C for 10h to obtain a precursor solution.

[0046] Step 2: At 50℃, 5.89g of high-alkali sodium aluminate was added to the above precursor solution to obtain a silicate gel with a molar ratio of Na2O:Al2O3:SiO2:H2O = 2.6:1:10:200, a molar ratio of beryllium sulfate tetrahydrate to silicon dioxide of 0.1, and Al2O3 in the directing agent accounting for 5% of the total Al2O3 mass in the gel. After stirring until the system was homogeneous, it was crystallized at 90℃ for 72h. The obtained product was washed, filtered, and dried at 120℃ to obtain mesoporous Be-NaY molecular sieve.

[0047] (2) After the Be-NaY molecular sieve is dried and dehydrated, it is placed in a reactor at 380℃ and then SiCl4 is introduced for an ultra-stable reaction for 30 min. The mass ratio of SiCl4 / mesoporous NaY molecular sieve is 0.3.

[0048] (3) A gas-phase ultrastable mesoporous NaY molecular sieve was mixed with deionized water at a solid / liquid mass ratio of 1:10. The mixture was heated to 60°C, slurried for 30 min, and then filtered. The filter cake was then slurried again with 10 times the amount of water. After filtration, a 2% (w / w) LaCl3 solution was added for ion exchange. The ion exchange conditions were: temperature 60°C, exchange time 90 min, and the weight ratio of LaCl3 solution to gas-phase ultrastable mesoporous NaY molecular sieve dry powder was 0.75 (the weight ratio of La2O3 to NaY molecular sieve dry powder was 0.01). Rare earth ultrastable Y molecular sieve was obtained.

[0049] Example 2

[0050] (1) Step 1: Add 17.48g of aluminum sulfate octadeca to 28g of deionized water to prepare a solution. Add the above aluminum sulfate solution and 9.35g of strontium chloride hexahydrate to 72.75g of silica sol and stir evenly. Add 9.48g of directing agent (1), mix evenly at 25℃, and crystallize at 80℃ for 28h to obtain the precursor solution.

[0051] Step 2: At 60℃, 8.3g of solid sodium aluminate was added to the above precursor solution to obtain a silicate gel with a molar ratio of Na2O:Al2O3:SiO2:H2O = 3.1:1:10:150, a molar ratio of strontium chloride hexahydrate to silicon dioxide of 0.07, and Al2O3 in the directing agent accounting for 3% of the total Al2O3 mass in the gel. After stirring until the system was homogeneous, it was crystallized at 100℃ for 64h. The obtained product was washed, filtered, and dried at 60℃ to obtain mesoporous Sr-NaY molecular sieve.

[0052] (2) After the dried and dehydrated Sr-NaY molecular sieve is refined, it is placed in a reactor at 380℃ and then SiCl4 is introduced for an ultra-stable reaction for 60 min. The mass ratio of SiCl4 / mesoporous NaY molecular sieve is 0.3.

[0053] (3) A gas-phase ultrastable mesoporous NaY molecular sieve was mixed with deionized water at a solid / liquid mass ratio of 1:10. The mixture was heated to 90℃, slurried for 30 min, and then filtered. The filter cake was then slurried again with 10 times the amount of water. After filtration, a rare earth solution with a mass fraction of 4% was added for ion exchange. The ion exchange conditions were: temperature of 60℃, exchange time of 60 min, and the weight ratio of LaCl3 solution to gas-phase ultrastable mesoporous NaY molecular sieve was 1.9 (the weight ratio of La2O3 to NaY molecular sieve dry powder was 0.05). Rare earth ultrastable Y molecular sieve was obtained.

[0054] Example 3

[0055] (1) Step 1: Dissolve 11.51g of aluminum nitrate in 46.51g of deionized water to obtain aluminum nitrate solution. Slowly add aluminum nitrate solution and 5.05g of calcium chloride to 139.51g of water glass and stir vigorously. Then add 19.13g of directing agent (3). After stirring evenly at 50℃, crystallize at 80℃ for 28h to obtain precursor solution.

[0056] Step 2: 7.61g of low-alkali sodium aluminate was added to the above precursor solution at 25℃ to obtain aluminosilicate gel with a molar ratio of Na2O:Al2O3:SiO2:H2O = 4.4:1:16:300, a molar ratio of calcium chloride to silicon dioxide of 0.09, and Al2O3 in the directing agent accounting for 7% of the total Al2O3 mass in the gel. After stirring until the system was homogeneous, it was crystallized at 110℃ for 72h. The obtained product was washed, filtered, and dried at 90℃ to obtain mesoporous Ca-NaY molecular sieve.

[0057] (2) After the Ca-NaY molecular sieve is dried and dehydrated, it is placed in a reactor at 300℃ and then SiCl4 is introduced for an ultra-stable reaction for 40 min. The mass ratio of SiCl4 / mesoporous NaY molecular sieve is 0.3.

[0058] (3) A gas-phase ultrastable mesoporous NaY molecular sieve was mixed with deionized water at a solid / liquid mass ratio of 1:10. The mixture was heated to 70°C, slurried for 30 min, and then filtered. The filter cake was then slurried again with 10 times the amount of water. After filtration, an 8% rare earth solution was added for ion exchange. The ion exchange conditions were: temperature 90°C, exchange time 90 min, and the weight ratio of LaCl3 solution to gas-phase ultrastable mesoporous NaY molecular sieve was 2.8 (the weight ratio of La2O3 to NaY molecular sieve dry powder was 0.15). Rare earth ultrastable Y molecular sieve was obtained.

[0059] Example 4

[0060] (1) Step 1: Dissolve 19.39g of aluminum sulfate octadeca in 27.6g of deionized water, add the above aluminum sulfate solution, 3.12g of magnesium hydroxide and 17.42g of directing agent to 192.82g of water glass. (2) After stirring evenly at 30℃, crystallize at 70℃ for 1h to obtain the precursor solution.

[0061] Step 2: At 80℃, 44.22g of high-alkali sodium aluminate was added to the above precursor solution to obtain a silicate gel with a molar ratio of Na2O:Al2O3:SiO2:H2O = 7.05:1:15:280, a molar ratio of magnesium hydroxide to silicon dioxide of 0.08, and Al2O3 in the directing agent accounting for 5% of the total Al2O3 mass in the gel. After stirring until the system was homogeneous, it was crystallized at 110℃ for 16h. The obtained product was washed, filtered, and dried at 110℃ to obtain mesoporous Mg-NaY molecular sieve.

[0062] (2) After the dried and dehydrated Mg-NaY molecular sieve is refined, it is placed in a reactor at 380℃, and then SiCl4 is introduced to carry out an ultra-stable reaction for 50 min. The mass ratio of SiCl4 / mesoporous NaY molecular sieve is 0.3.

[0063] (3) A gas-phase ultrastable mesoporous NaY molecular sieve was mixed with deionized water at a solid / liquid mass ratio of 1:10. The mixture was heated to 80℃, slurried for 30 min, and then filtered. The filter cake was then slurried again with 10 times the amount of water. After filtration, a rare earth solution with a mass fraction of 12% was added for ion exchange. The ion exchange conditions were: temperature of 60℃, exchange time of 60 min, and the weight ratio of LaCl3 solution to gas-phase ultrastable mesoporous NaY molecular sieve was 1.25 (the weight ratio of La2O3 to NaY molecular sieve dry powder was 0.10). Rare earth ultrastable Y molecular sieve was obtained.

[0064] Example 5

[0065] (1) Step 1: Mix 34.69g silica sol, 5.09g aluminum nitrate, 5.28g barium nitrate, 15.68g directing agent (3) and 42.53g deionized water at 55°C and crystallize at 80°C for 28h to obtain a precursor solution.

[0066] Step 2: Add 26.26g of high-alkali sodium aluminate to the above-mentioned solution and stir at 75℃ until the system is homogeneous to obtain a metal aluminosilicate gel. The molar ratio of each component in the gel is Na2O:Al2O3:SiO2:H2O = 3.0:1:12:240, the molar ratio of barium nitrate to silicon dioxide is 0.08, and the mass of Al2O3 in the directing agent accounts for 8% of the total Al2O3 mass in the gel. Crystallize at 110℃ for 54h. The obtained product is washed, filtered, and dried at 100℃ to obtain mesoporous Ba-NaY molecular sieve.

[0067] (2) After the dried and dehydrated Ba-NaY molecular sieve is refined, it is placed in a reactor at 380℃, and then SiCl4 is introduced to carry out an ultra-stable reaction for 35 minutes. The mass ratio of SiCl4 / mesoporous NaY molecular sieve is 0.3.

[0068] (3) A gas-phase ultrastable mesoporous NaY molecular sieve was mixed with deionized water at a solid / liquid mass ratio of 1:10. The mixture was heated to 80℃, slurried for 30 min, and then filtered. The filter cake was then slurried again with 10 times the amount of water. After filtration, a rare earth solution with a mass fraction of 10% was added for ion exchange. The ion exchange conditions were: temperature of 90℃, exchange time of 70 min, and weight ratio of LaCl3 solution to gas-phase ultrastable mesoporous NaY molecular sieve of 1.0 (weight ratio of La2O3 to NaY molecular sieve dry powder of 0.067) to obtain rare earth ultrastable Y molecular sieve.

[0069] Comparative Example 1

[0070] Comparative Example 1 uses the same material ratio and the same stepwise crystallization process as Example 1, except that no alkaline earth metals are added to the materials of Comparative Example 1, and it includes the following steps:

[0071] (1) Step 1: Dissolve 9.46g of aluminum sulfate octadecylhydrate in 11.91g of deionized water to obtain an aluminum sulfate solution. Add the above aluminum sulfate solution to 47.95g of water glass, stir vigorously, and then add 5.27g of directing agent (1). Stir evenly at 40°C, and crystallize at 60°C for 10h to obtain a precursor solution.

[0072] Step 2: At 50℃, 5.89g of high alkali was added to the above precursor solution to obtain an aluminosilicate gel with a molar ratio of Na2O:Al2O3:SiO2:H2O = 2.6:1:10:200. The mass of Al2O3 in the directing agent accounted for 5% of the total mass of Al2O3 in the gel. After stirring until the system was homogeneous, it was crystallized at 90℃ for 72h. The obtained product was washed, filtered, and dried at 120℃ to obtain mesoporous NaY molecular sieve.

[0073] (2) After the NaY molecular sieve is dried and dehydrated, it is refined and placed in a reactor at 380°C. Then, SiCl4 is introduced to carry out an ultra-stable reaction for 30 minutes. The mass ratio of SiCl4 to mesoporous NaY molecular sieve is 0.3.

[0074] (3) Gas-phase ultrastable mesoporous NaY molecular sieve was mixed with deionized water at a solid / liquid mass ratio of 1:10. The mixture was heated to 60℃, pulped for 30 min, and then filtered. The filter cake was then pulped again with 10 times the amount of water. After filtration, 2% (w / w) of LaCl3 solution was added for ion exchange. The ion exchange conditions were: temperature 60℃, exchange time 90 min, and weight ratio of LaCl3 solution / dry molecular sieve basis of 0.75 (weight ratio of La2O3 to NaY molecular sieve dry powder of 0.01) to obtain rare earth ultrastable Y molecular sieve.

[0075] Comparative Example 2

[0076] Comparative Example 1 used the same final material ratio as Example 1, and alkaline earth metals were added to the synthesis system. The difference was that Comparative Example 1 used a one-step crystallization process, which included the following steps:

[0077] (1) Step 1: Dissolve 9.46g of aluminum sulfate octadechydrate in 11.91g of deionized water to obtain aluminum sulfate solution. Add 2.98g of beryllium sulfate tetrahydrate and the above aluminum sulfate solution to 47.95g of water glass. After vigorous stirring, add 5.89g of high-alkali sodium aluminate to the above precursor solution, and then add 5.27g of directing agent (1) to obtain aluminosilicate gel with a molar ratio of Na2O:Al2O3:SiO2:H2O=2.6:1:10:200. After stirring evenly at 40℃, crystallize at 90℃ for 72h. The obtained product is washed, filtered, and dried at 120℃ to obtain molecular sieve sample;

[0078] (2) After the Be-NaY molecular sieve is dried and dehydrated, it is placed in a reactor at 380℃ and then SiCl4 is introduced for an ultra-stable reaction for 30 min. The mass ratio of SiCl4 / mesoporous NaY molecular sieve is 0.3.

[0079] (3) Gas-phase ultrastable mesoporous NaY molecular sieve was mixed with deionized water at a solid / liquid mass ratio of 1:10. The mixture was heated to 60℃, pulped for 30 min, and then filtered. The filter cake was then pulped again with 10 times the amount of water. After filtration, 2% (w / w) of LaCl3 solution was added for ion exchange. The ion exchange conditions were: temperature 60℃, exchange time 90 min, and weight ratio of LaCl3 solution / dry molecular sieve basis of 0.75 (weight ratio of La2O3 to NaY molecular sieve dry powder of 0.01) to obtain rare earth ultrastable Y molecular sieve.

[0080] The physicochemical properties of rare earth ultrastable Y molecular sieves obtained in each embodiment and comparative example are compared, and their pore structure parameters are listed in Table 1.

[0081] Table 1. Pore structure parameters of the examples and comparative samples.

[0082]

[0083] Figure 1 The XRD patterns are those of Comparative Example 1, Comparative Example 2, Example 1, Example 2, Example 3, Example 4, and Example 5; from Figure 1 It can be seen that, compared with Comparative Example 1, the ultrastable Y molecular sieves provided in Examples 1, 2, 3, and 4 are typical Y-type molecular sieves. As shown in Table 1, the relative crystallinity of each molecular sieve in Examples 1, 2, 3, and 4 is still at a higher level than that in Comparative Example 1, indicating that the gas-phase ultrastable treatment did not have an additional impact on the crystallinity of the mesoporous NaY molecular sieve.

[0084] Compared to Example 1, Comparative Example 1 used the same material ratio and the same stepwise crystallization process, except that no alkaline earth metal was added to the materials in Comparative Example 1. Comparative Example 2 used the same final material ratio as Example 1, and alkaline earth metal was added to the synthesis system, except that Comparative Example 1 used a one-step crystallization process. As can be seen from the data in Table 1, the final Y molecular sieve products obtained in both Comparative Example 1 and Comparative Example 2 have significantly lower mesoporous specific surface areas than the corresponding data for the products in each example.

[0085] Figure 2A These are the N2 adsorption-desorption isotherms for Comparative Example 1 and Example 4. Figure 2BThe figures show the pore size distribution of Comparative Example 1 and Example 4. From the N2 adsorption-desorption isotherms and pore size stepwise distribution, it can be seen that the adsorption-desorption isotherms of the ultrastable Y molecular sieve provided in Comparative Example 1 are typical Type I curves, without hysteresis loops, and no obvious mesopore distribution was observed. This indicates that conventional gas-phase ultrastable Y molecular sieves are typical microporous materials, and the gas-phase ultrastable process does not contribute to the formation of mesopores. In contrast, the adsorption-desorption isotherms of the ultrastable Y molecular sieve provided in Example 4 are Type IV curves with H3-type hysteresis loops, and the pore size stepwise distribution shows obvious mesopore stepwise distribution. This indicates that Example 4 preserved the rich mesopore structure of the original mesoporous NaY molecular sieve during the gas-phase ultrastable process. Combined with the data in Table 1, the mesopore specific surface area of ​​the ultrastable Y molecular sieve provided in Example 4 is 126.7 m². 2 ·g -1 The mesopore volume is 0.14 cm³. 3 ·g -1 The mesopore volume of conventional ultrastable Y molecular sieves is 0.04 cm³. 3 / g, the mesopore volume of the ultrastable Y molecular sieve provided in Example 4 is approximately 3.5 times that of the conventional ultrastable Y molecular sieve.

[0086] As shown in Table 1, after rare earth exchange, the rare earth content of the conventional ultrastable Y molecular sieve in Comparative Example 1 was 1.34%, while the rare earth contents of Examples 1, 2, 3, 4, and 5 were 1.24%, 3.84%, 4.56%, 4.36%, and 4.19%, respectively. When the amount of rare earth exchanged increased from 1% to 15%, the rare earth content in the molecular sieve also showed an increasing trend.

[0087] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for gas phase ultrastabilization and rare earth modification of mesoporous NaY molecular sieve, characterized in that, The method comprises the following steps: S1, mixing a first silicon source, a first aluminum source, an alkali source and water, and then aging to obtain a NaY molecular sieve structure directing agent; S2, mixing a second silicon source, a second aluminum source, the NaY molecular sieve structure directing agent and a precursor of a metal M having a defect structure promoting effect to obtain a precursor solution, and performing first crystallization on the precursor solution at 60-80 DEG C for 1-28 h; S3, adding a third aluminum source to the precursor solution after the first crystallization to obtain a metal silico-aluminate gel, and performing second crystallization on the metal silico-aluminate gel at 90-110 DEG C for 16-72 h to obtain a mesoporous NaY molecular sieve, wherein the metal M in the metal silico-aluminate gel is in the form of an oxide, the silicon element is in the form of SiO2, and the molar ratio of the oxide of the metal M to SiO2 is 0.07-0.10; S4, drying and dehydrating the mesoporous NaY molecular sieve, and then performing ultrastable reaction on the mesoporous NaY molecular sieve with SiCl4 at 200-500 DEG C for 30-60 min to obtain a gas phase ultrastable mesoporous NaY molecular sieve; S5, mixing the gas phase ultrastable mesoporous NaY molecular sieve with deionized water, beating, and adding a rare earth solution to perform rare earth exchange to obtain a rare earth ultrastable mesoporous Y molecular sieve.

2. The method for the gas phase stabilization and rare earth modification of mesoporous NaY molecular sieves according to claim 1, characterized in that, In step S1, the first silicon source, the first aluminum source, the alkali source and water are in the form of SiO2, Al2O3, Na2O and H2O respectively, and the molar ratio is (10-30):1:(10-30):(260-480).

3. The method for the gas phase stabilization and rare earth modification of mesoporous NaY molecular sieves according to claim 1, characterized in that, The molar ratio of SiO2, Al2O3, Na2O and H2O in the metal silico-aluminate gel is (5-20):1:(2-10):(150-300).

4. The method for the gas phase stabilization and rare earth modification of mesoporous NaY molecular sieves according to claim 1, characterized in that, The first silicon source and the second silicon source are the same or different, and each comprises one or more of tetraethyl orthosilicate, silica sol, silicon powder, silicic acid, white carbon black and water glass.

5. The method for the gas phase stabilization and rare earth modification of mesoporous NaY molecular sieves according to claim 1, characterized in that, The first aluminum source, the second aluminum source and the third aluminum source are the same or different, and each comprises one or more of high-alkali sodium metaborate solution, low-alkali sodium metaborate solution, sodium metaborate, aluminum oxide, aluminum sulfate, aluminum isopropoxide, pseudo-boehmite, aluminum chloride, aluminum citrate, aluminum hydroxide and aluminum nitrate.

6. The method for the gas phase stabilization and rare earth modification of mesoporous NaY molecular sieves according to claim 1, characterized in that, The metal M is an alkaline earth metal, and the alkaline earth metal is one or more of Ca, Mg, Be, Ba and Sr.

7. The method for the gas phase stabilization and rare earth modification of mesoporous NaY molecular sieves according to claim 1, characterized in that, In step S1, the aging temperature is 30-50 DEG C, and the aging time is 1-28 h; in step S2, the precursor solution is mixed at 25-60 DEG C; in step S3, the metal silico-aluminate gel is mixed at 25-80 DEG C; and after the second crystallization in step S3, the product is cooled, washed, filtered, and dried at 60-120 DEG C to obtain the mesoporous NaY molecular sieve.

8. The method for the gas phase stabilization and rare earth modification of mesoporous NaY molecular sieves according to claim 1, characterized in that, In step S3, the mass of Al2O3 in the NaY molecular sieve structure directing agent accounts for 3-12% of the mass of Al2O3 in the metal silico-aluminate gel.

9. The method for the gas phase stabilization and rare earth modification of mesoporous NaY molecular sieves according to claim 1, characterized in that, In step S4, the mass ratio of SiCl4 to the mesoporous NaY molecular sieve is 0.2-0.

5.

10. The method for the gas phase stabilization and rare earth modification of mesoporous NaY molecular sieves according to claim 1, characterized in that, In step S5, the concentration of the rare earth solution is 2-12 wt%, and the mass ratio of the rare earth solution to the gas phase ultrastable mesoporous NaY molecular sieve dry powder is 0.01-0.

15.

11. The method for the gas phase stabilization and rare earth modification of mesoporous NaY molecular sieves according to claim 1, characterized in that, In step S5, the pH value of the system is adjusted to 3.0-4.5, the ion exchange temperature is 60-90℃, the ion exchange time is 60-90min, and after the exchange, the product is filtered, washed and dried.

12. A catalytic cracking catalyst characterized by, The rare earth ultrastable mesoporous Y molecular sieve is obtained by a gas phase ultrastable and rare earth modification method comprising the mesoporous NaY molecular sieve according to any one of claims 1-11.

Images