Hierarchical pore Y-type molecular sieve and preparation method thereof

Abstract

The invention relates to the field of nano catalytic materials, and discloses a hierarchical pore Y-type molecular sieve and a preparation method thereof. The total volume of pores of the molecular sieve is 0.3-0.45 cm < 3 > / g; wherein the total volume of mesopores with the pore diameter of 3-50 nm of the molecular sieve is 0.12-0.35 cm < 3 > / g; the relative crystallinity of the molecular sieve is 65-100%. The molecular sieve provided by the invention takes low-cost soluble starch as a template, so that the mesoporous volume is effectively increased, and the relative crystallinity of the molecular sieve is maintained.

Description

Technical Field

[0001] The present invention relates to the field of nano-catalytic materials, and particularly to a hierarchical pore Y-type molecular sieve and a preparation method thereof. Background Art

[0002] Petroleum products are widely used in industries such as industry, agriculture, and national defense construction. The petroleum refining industry is of great significance to the national economy and social development. Catalytic cracking (FCC), as the core process for heavy oil lightening, is currently the most important secondary processing process in the petroleum refining industry and largely depends on the selection of catalysts. Among them, Y molecular sieve, as the main active component of the most commonly used FCC catalyst, has attracted much attention. However, the pore channels of traditional microporous Y molecular sieves are narrow, which limits the diffusion of macromolecular reactants and products and reduces the accessibility of active sites. In addition, the long residence time of macromolecules in the pore channels leads to over-cracking to form coke, thus accelerating the deactivation of the molecular sieve. The construction of hierarchical pores can effectively solve the above problems of Y molecular sieve, improve the conversion rate of reactants, the selectivity of target products, and the catalyst life. Therefore, the research and development of hierarchical pore Y molecular sieve catalytic materials is of great significance for further improving the catalytic cracking reaction efficiency.

[0003] Currently, the existing preparation methods of hierarchical pore molecular sieves include "top-down" and "bottom-up" methods. The essence of "top-down" is to introduce mesoporous structures through post-treatment methods such as desilication or dealumination. The operation is relatively simple, but the experimental reproducibility is poor. At the same time, the process of removing framework atoms will damage the framework structure of the molecular sieve, affecting the relative crystallinity and framework silicon-aluminum ratio of the molecular sieve. The "bottom-up" method mainly includes hard template method, soft template method, and template-free method. The template-free method is a newly emerging preparation method, which is not yet mature, has a low degree of pore size regulation, and poor controllability. Commonly used soft templates are generally amphiphilic macromolecules, and surfactants, water-soluble cationic polymers, and organosilane reagents are often selected. Carbon templates are the most common hard templates, mainly including carbon black, carbon nanoparticles, carbon nanotubes, ordered mesoporous carbon, etc. The template method can maintain the good crystal structure of the molecular sieve and prepare hierarchical pore molecular sieves with good catalytic performance. However, the templates generally have high costs and complex post-treatment, and environmental pollution problems will occur during removal. Therefore, it is very urgent to develop a preparation method for hierarchical pore Y-type molecular sieves that can effectively increase the mesopore volume, maintain its relative crystallinity, and is simple, economical, and environmentally friendly. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems existing in the prior art, such as high template cost, complex post-treatment, low degree of pore size regulation, and easy influence on the crystallinity of the molecular sieve during preparation. A hierarchical pore Y-type molecular sieve and a preparation method thereof are provided. The hierarchical pore Y-type molecular sieve uses low-cost soluble starch as a template, which not only effectively increases the mesopore volume but also maintains the relative crystallinity of the molecular sieve.

[0005] To achieve the above object, a first aspect of the present invention provides a hierarchical pore Y-type molecular sieve, wherein the total pore volume of the molecular sieve is 0.3 - 0.45 cm 3 / g; wherein the total volume of mesopores with a pore diameter of 3 - 50 nm in the molecular sieve is 0.12 - 0.35 cm 3 / g; the relative crystallinity of the molecular sieve is 65 - 100%.

[0006] A second aspect of the present invention provides a method for preparing a hierarchical pore Y-type molecular sieve, wherein the preparation method includes the following steps:

[0007] S1. In the presence of a first solvent, an aluminum source and a silicon source are mixed under alkaline conditions for a first reaction to obtain a precursor mixture;

[0008] S2. The precursor mixture and water-soluble starch are mixed for a second reaction to obtain a post-second reaction mixture; the seed directing agent and the post-second reaction mixture are mixed for crystallization; wherein the time of the second reaction is less than or equal to 15 h;

[0009] S3. The solid phase product obtained by the crystallization is washed and dried;

[0010] S4. The solid obtained in S3 is calcined.

[0011] A third aspect of the present invention provides a hierarchical pore Y-type molecular sieve prepared by the preparation method provided by the present invention.

[0012] Through the above technical solutions, the beneficial effects of the present invention include:

[0013] The present invention uses a green, low-cost, and abundant polysaccharide biomass - soluble starch as a template, and prepares hierarchical pore Y zeolite with a green and economical templating agent. Compared with traditional Y zeolite, the present invention effectively increases the mesopore volume of the hierarchical pore Y zeolite, and the hierarchical pore Y zeolite can maintain a high relative crystallinity. At the same time, the prepared hierarchical pore Y zeolite has a uniform particle size distribution, which is of great significance for the technical development and popularization of the green synthesis of hierarchical pore molecular sieves.

[0014] The molecular sieve provided by the present invention optimizes the pore structure of the molecular sieve while maintaining a relatively high relative crystallinity compared to the traditional NaY molecular sieve. Using soluble starch as a template to mediate the synthesis of hierarchical pore NaY molecular sieve, the operation process is simple, green and economical. The relatively high relative crystallinity indicates that the molecular sieve can maintain a relatively complete crystal structure without causing excessive loss of the framework species of the traditional NaY molecular sieve, and can provide effective active sites for reactions such as catalytic cracking and isomerization. At the same time, the increase in the mesopore volume can effectively solve the diffusion limitation of substrate and product molecules, improve their transport efficiency, and is beneficial to improving the selectivity of product molecules. In addition, the introduction of mesopores exposes more active sites, increases the accessibility of active sites, and is beneficial to optimizing the conversion rate of substrate molecules. Therefore, the molecular sieve provided by the present invention is a product with great application potential.

[0015] In a preferred embodiment of the present invention, the degree of increase in the total volume of mesopores with a pore diameter of 3 - 10 nm is significantly higher than that of mesopores with a pore diameter of 10 - 50 nm, forming mesopores with a pore diameter concentrated in 3 - 10 nm. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the XRD pattern of hierarchical pore NaY-1 prepared in Example 1 of the present invention and NaY-13 prepared in Comparative Example 4 of the present invention;

[0017] Figure 2 is the pore size diagram of hierarchical pore NaY-1 prepared in Example 1 of the present invention and NaY-13 prepared in Comparative Example 4 of the present invention;

[0018] Figure 3 is the XRD pattern of hierarchical pore NaY-2 prepared in Example 2 of the present invention and NaY-13 prepared in Comparative Example 4 of the present invention;

[0019] Figure 4 is the pore size diagram of hierarchical pore NaY-2 prepared in Example 2 of the present invention and NaY-13 prepared in Comparative Example 4 of the present invention;

[0020] Figure 5 is the XRD pattern of hierarchical pore NaY-3 prepared in Example 3 of the present invention and NaY-13 prepared in Comparative Example 4 of the present invention;

[0021] Figure 6 is the pore size diagram of hierarchical pore NaY-3 prepared in Example 3 of the present invention and NaY-13 prepared in Comparative Example 4 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0023] The first aspect of the present invention provides a hierarchical pore Y-type molecular sieve, wherein the total pore volume of the molecular sieve is 0.3 - 0.45 cm 3 / g; wherein the total volume of mesopores with a pore diameter of 3 - 50 nm in the molecular sieve is 0.12 - 0.35 cm 3 / g; the relative crystallinity of the molecular sieve is 65 - 100%.

[0024] According to the present invention, preferably, in the molecular sieve, the total volume of mesopores with a pore diameter of 3 - 10 nm is 0.04 - 0.1 cm 3 / g, and the total volume of mesopores with a pore diameter of 10 - 50 nm is 0.08 - 0.25 cm 3 / g.

[0025] Furthermore, in the molecular sieve, the total volume of mesopores with a pore diameter of 3 - 10 nm is 0.07 - 0.1 cm 3 / g, and the total volume of mesopores with a pore diameter of 10 - 50 nm is 0.16 - 0.25 cm 3 / g.

[0026] Compared with traditional Y-type molecular sieves, the increase in the volume of mesopores in the two pore diameter ranges is significantly different. The increase in the volume of mesopores with a pore diameter of 3 - 10 nm in the molecular sieve is much higher than that of mesopores with a pore diameter of 10 - 50 nm. Without having a great negative impact on the relative crystallinity of the molecular sieve, the diffusion efficiency of larger-sized substrate molecules can be effectively improved.

[0027] In the present invention, the mesopores with a pore diameter of 3 - 10 nm include mesopores with a pore diameter of 10 nm, and the mesopores with a pore diameter of 10 - 50 nm do not include mesopores with a pore diameter of 10 nm.

[0028] According to the present invention, preferably, the specific surface area of the molecular sieve is 450 - 700 m 2 / g.

[0029] According to the present invention, preferably, the relative crystallinity of the molecular sieve is 80 - 100%.

[0030] The second aspect of the present invention provides a preparation method of a hierarchical pore Y-type molecular sieve, wherein the preparation method includes the following steps:

[0031] S1. In the presence of a first solvent, an aluminum source and a silicon source are mixed under alkaline conditions to carry out a first reaction to obtain a precursor mixture;

[0032] S2. The precursor mixture and water-soluble starch are mixed to carry out a second reaction to obtain a mixture after the second reaction; the seed directing agent and the mixture after the second reaction are mixed for crystallization; wherein, the time of the second reaction is less than or equal to 15 h;

[0033] S3. The solid-phase product obtained by the crystallization is washed and dried;

[0034] S4. The solid obtained in S3 is calcined.

[0035] In the present invention, the silicon source and the aluminum source react to form a silica-alumina precursor gel, and the caramelization reaction is utilized to incorporate into the precursor gel through the hydrogen bond bridging between the hydroxyl groups on the starch and the framework Si-OH or Al-OH for crystallization; the obtained solid-phase substance is centrifugally washed to neutrality and dried; the dried substance is calcined to remove the template to obtain a hierarchical pore Y zeolite.

[0036] According to the present invention, preferably, in S1, the aluminum source is selected from water-soluble aluminum salts and / or water-soluble meta-aluminates, preferably selected from sodium meta-aluminate and / or aluminum sulfate.

[0037] According to the present invention, preferably, the silicon source is a silicate, preferably sodium silicate.

[0038] According to the present invention, preferably, the first solvent is water.

[0039] According to the present invention, preferably, in S1, the amount of the aluminum source is based on the molar amount of Al 2 O 3 , and the amount of the silicon source is based on the molar amount of SiO 2 . When carrying out the first reaction, the amounts of the aluminum source and the silicon source are such that the molar ratio of Al 2 O 3 to SiO 2 is (1-20):(1-20).

[0040] Further, when the aluminum source is sodium meta-aluminate and aluminum sulfate, the amount of the aluminum source is based on the molar amounts of Al 2 O 3 and Na 2 O, and the amount of the silicon source is based on the molar amounts of Na 2 O and SiO 2 . When carrying out the first reaction, the amounts of the aluminum source and the silicon source are such that Al 2 O 3 , Na 2 O and SiO2 The molar ratio is (1 - 20):(1 - 20):(1 - 20).

[0041] According to the present invention, preferably, the amount of the first solvent is such that the weight ratio of the first solvent to SiO in the silicon source 2 is (1 - 20):1.

[0042] According to the present invention, the first solvent can be mixed with the aluminum source and the silicon source by being added separately for the first reaction, or the aluminum source and the silicon source can be mixed in the form of aqueous solutions respectively, and a part of the first solvent is added together with the aluminum source and the silicon source, and then an appropriate amount of the first solvent is added additionally. According to a preferred embodiment of the present invention, sodium aluminate and aluminum sulfate are added in the form of sodium aluminate aqueous solution and aluminum sulfate aqueous solution respectively, and sodium silicate is added in the form of water glass.

[0043] According to the present invention, preferably, the first reaction is carried out under the condition that the pH value is 9 - 14.

[0044] According to the present invention, after the aluminum source and the silicon source are mixed with the first solvent, an alkali solution can be added to adjust the pH value of the first reaction system, or the alkali solution can be added together with the aqueous solution of the aluminum source or the alkali solution can be added together with the aqueous solution of the silicon source.

[0045] According to a preferred embodiment of the present invention, a basic sodium aluminate aqueous solution with a concentration of 3 - 8 mol / L and a pH value of 9 - 13 is first prepared, and then it is mixed with an aluminum sulfate aqueous solution with a concentration of 1 - 5 mol / L, water glass containing 200 - 270 g / L of SiO 2 and 60 - 90 g / L of Na 2 O and water in a volume ratio of (0.5 - 5):(2 - 6):(8 - 30):(4 - 12) for the first reaction. Among them, the water glass can be commercially available, for example, it can be purchased from Changling Catalyst Branch of China Petroleum & Chemical Corporation.

[0046] According to a specific embodiment of the present invention, the preparation method of the basic sodium aluminate aqueous solution includes: separately preparing an Al(OH) 3 solution with a concentration of 2 - 10 mol / L and an NaOH solution with a concentration of 5 - 15 mol / L, and then mixing them to obtain a basic sodium aluminate solution with a concentration of 3 - 8 mol / L and a pH value of 9 - 13.

[0047] According to the present invention, preferably, the temperature of the first reaction is 60 - 85 °C and the time is 0.5 - 3 h.

[0048] According to the present invention, preferably, the first reaction is carried out in an oil bath.

[0049] According to the present invention, preferably, when performing the second reaction, the amount of the water-soluble starch is such that the weight ratio of SiO in the silicon source 2 to the water-soluble starch is (1 - 15):1.

[0050] The present invention places no particular limitation on the source of the water-soluble starch. For example, the water-soluble starch may be potato starch, corn starch, wheat starch, tapioca starch, etc.

[0051] According to the present invention, preferably, the temperature of the second reaction is 60 - 85°C and the time is 3 - 12 h.

[0052] According to the present invention, preferably, in S2, the method for preparing the seed directing agent includes: in the presence of a second solvent, mixing sodium aluminate and sodium silicate under alkaline conditions to perform a third reaction, and then aging.

[0053] According to the present invention, preferably, the amount of sodium aluminate is based on the total molar amount of Al 2 O 3 and Na 2 O, and the amount of sodium silicate is based on the total molar amount of Na 2 O and SiO 2 . When performing the third reaction, the amounts of sodium aluminate and sodium silicate are such that the molar ratio of Al 2 O 3 , Na 2 O and SiO 2 is (1 - 30):(1 - 30):(1 - 30).

[0054] According to the present invention, preferably, the amount of the second solvent is such that the weight ratio of the second solvent to SiO in sodium silicate 2 is (50 - 80):1.

[0055] According to the present invention, preferably, the second solvent is water.

[0056] According to the present invention, the second solvent can be mixed with sodium aluminate and sodium silicate and undergo the third reaction by being added separately, or sodium aluminate and sodium silicate can be mixed in the form of aqueous solutions, with a part of the second solvent added together with sodium aluminate and sodium silicate, and then an appropriate amount of the second solvent is added. According to a preferred embodiment of the present invention, sodium aluminate and sodium silicate are added in the form of an aqueous solution of sodium aluminate and water glass, respectively.

[0057] According to the present invention, preferably, the third reaction is carried out under the condition that the pH value is 9 - 11.

[0058] According to the present invention, sodium aluminate and sodium silicate can be mixed with a second solvent, and then an alkali solution can be added to adjust the pH value of the third reaction system. Alternatively, the alkali solution can be added together with the aqueous sodium aluminate solution or water glass.

[0059] According to a specific embodiment of the present invention, the preparation method of the seed directing agent includes: mixing an aqueous sodium aluminate solution with 230 - 300 g / L of Na 2 O and 30 - 60 g / L of Al 2 O 3 and having a pH value of 9 - 14, water, and water glass containing 200 - 270 g / L of SiO 2 and 60 - 90 g / L of Na 2 O in a volume ratio of (3 - 15):(0.01 - 1):(5 - 30) for a third reaction. Among them, the aqueous sodium aluminate solution with 230 - 300 g / L of Na 2 O and 30 - 60 g / L of Al 2 O 3 and having a pH value of 9 - 14, as well as the water glass containing 200 - 270 g / L of SiO 2 and 60 - 90 g / L of Na 2 O can both be commercially available, for example, they can be purchased from Changling Catalyst Branch of China Petroleum & Chemical Corporation.

[0060] According to the present invention, preferably, the temperature of the third reaction is 15 - 25 °C and the time is 15 - 120 min.

[0061] According to the present invention, preferably, the temperature of the aging is 20 - 40 °C and the time is 10 - 24 h.

[0062] According to the present invention, preferably, in S2, based on the total weight of the mixture after the second reaction, the dosage of the seed directing agent is 5 - 30 wt%.

[0063] In order to make the seed directing agent and the mixture after the second reaction mix more uniformly, and thus better crystallization, in S2, the mixing method includes: stirring the seed directing agent and the mixture after the second reaction at room temperature for 0.5 - 4 h.

[0064] According to the present invention, preferably, the temperature of the crystallization is 90 - 110 °C and the time is 24 - 60 h.

[0065] According to the present invention, preferably, in S3, the washing conditions are such that the pH value of the washed material is 7.2 - 8.2.

[0066] According to a preferred embodiment of the present invention, the washing is carried out by centrifugal washing. The method of centrifugal washing includes: centrifugally washing the solid-phase product obtained by crystallization at a rotation speed of 5000 - 10000 rpm for 3 - 15 min until the pH value reaches 7.2 - 8.2.

[0067] According to the present invention, the drying can be carried out in a vacuum drying oven. Preferably, the drying temperature is 50 - 100 °C and the time is 10 - 24 h.

[0068] According to the present invention, preferably, in S4, the calcination temperature is 500 - 650 °C and the time is 5 - 20 h.

[0069] The third aspect of the present invention provides a hierarchical pore Y-type molecular sieve prepared by the preparation method provided by the present invention.

[0070] The present invention will be described in detail below through examples and comparative examples. In the following examples and comparative examples, unless otherwise specified, all are conventional methods; the materials used, unless otherwise specified, can be obtained from commercial channels.

[0071] The highly alkaline sodium aluminate solution is provided by Sinopec Catalyst Changling Co., Ltd., with a pH value of 12; the content of Na 2 O is 276.6 g / L, and the content of Al 2 O 3 is 40.3 g / L.

[0072] The water glass is provided by Sinopec Catalyst Changling Co., Ltd., with the SiO 2 content of 258.4 g / L and the Na 2 O content of 82.67 g / L.

[0073] The following examples are used to illustrate the preparation of the hierarchical pore Y-type molecular sieve.

[0074] Example 1

[0075] S1. Add 0.1 mL of deionized water to 7.7 mL of the highly alkaline sodium aluminate solution, and while stirring, gradually dropwise add 10.2 mL of water glass (the dosages of the highly alkaline sodium aluminate solution and water glass are such that the molar ratio of Al 2 O 3 , Na 2 O and SiO 2 is 1:16:15; the pH value of the obtained mixed solution is 10; the total amount of water is such that the molar ratio of water to SiO 2The weight ratio is 64:1 (the total amount of water used includes the deionized water added, the water contained in the highly alkaline sodium aluminate solution, and the water contained in the sodium silicate). Stir continuously at 20 °C for 30 min. Age at 30 °C for 18 h to obtain the seed directing agent.

[0076] Prepare a 5.8 mol / L Al(OH) 3 solution and a 7.8 mol / L NaOH solution respectively. Mix and stir them until the solution is clear and transparent to obtain a 1.45 mL low-alkaline sodium aluminate solution with a concentration of 6.3 mol / L and a pH value of 11. Under the condition of an 80 °C oil bath, mix and stir the low-alkaline sodium aluminate solution, 3.77 mol / L Al 2 (SO 4 ) 3 solution, 10.67 mL of sodium silicate and 6.3 mL of water for 1.5 h to obtain a precursor mixture with a pH value of 10. Among them, the dosages of the low-alkaline sodium aluminate solution, Al 2 (SO 4 ) 3 solution and sodium silicate are such that the molar ratio of Al 2 O 3 , Na 2 O, and SiO 2 is 1:3:8; the total amount of water used is such that the weight ratio of water to SiO 2 in the sodium silicate is 7.4:1 (the total amount of water used includes the deionized water added, the water contained in the low-alkaline sodium aluminate solution, the water contained in the Al 2 (SO 4 ) 3 solution, and the water contained in the sodium silicate).

[0077] S2. Under the condition of an 80 °C oil bath, add soluble starch to the precursor mixture and continue stirring for 12 h. The dosage of the soluble starch is such that the weight ratio of SiO 2 to the soluble starch is 3:1. At room temperature, based on the total weight of the soluble starch and the precursor mixture, add 9 wt% of the seed directing agent and stir for 1 h, then hydrothermally crystallize at 100 °C for 48 h.

[0078] S3. Centrifuge and wash the solid substance obtained after opening the autoclave, separate at 6000 rpm for 8 min, and wash multiple times until the pH value is 7.8. Dry in a 60 °C vacuum drying oven for 18 h to obtain a solid white powder.

[0079] S4. Calcinate the obtained powder at 600 °C for 10 h to obtain the hierarchical pore molecular sieve NaY-1.

[0080] The above-mentioned soluble starch is corn starch.

[0081] Example 2

[0082] S1. Add 0.35 mL of deionized water to 10.1 mL of highly alkaline sodium aluminate solution. While stirring, gradually add 15.87 mL of water glass drop by drop (the amounts of highly alkaline sodium aluminate solution and water glass are such that the molar ratio of Al 2 O 3 , Na 2 O and SiO 2 is 1:5:1; the pH value of the resulting mixture is 10.5; the total amount of water is such that the weight ratio of water to SiO 2 in water glass is 76:1 (the total amount of water includes the added deionized water, the water contained in the highly alkaline sodium aluminate solution, and the water contained in the water glass), and continue to stir at 23 °C for 45 min. Age at 35 °C for 15 h to obtain a seed directing agent.

[0083] Prepare 7.9 mol / L Al(OH) 3 solution and 14.6 mol / L NaOH solution respectively. Mix and stir them until the solution is clear and transparent to obtain 2.45 mL of low-alkaline sodium aluminate solution with a concentration of 4.5 mol / L and a pH value of 11.7. Under the condition of a 60 °C oil bath, mix and stir the low-alkaline sodium aluminate solution, 4.32 mol / L Al 2 (SO 4 ) 3 solution, 20.96 mL of water glass and 10.5 mL of water for 1 h to obtain a precursor mixture with a pH value of 11.3. Among them, the amounts of low-alkaline sodium aluminate solution, Al 2 (SO 4 ) 3 solution and water glass are such that the molar ratio of Al 2 O 3 , Na 2 O, SiO 2 is 3:8:17; the total amount of water is such that the weight ratio of water to SiO 2 in water glass is 10.1:1 (the total amount of water includes the added deionized water, the water contained in the low-alkaline sodium aluminate solution, the water contained in Al 2 (SO 4 ) 3 solution and the water contained in the water glass).

[0084] S2. Under the condition of a 60 °C oil bath, add soluble starch to the precursor mixture and continue to stir for 10 h. The amount of soluble starch is such that the weight ratio of SiO 2 to soluble starch is 1.5:1. At room temperature, based on the total weight of soluble starch and the precursor mixture, add 16 wt% of the seed directing agent and stir for 2.5 h, and hydrothermally crystallize at 110 °C for 36 h.

[0085] S3. Centrifuge and wash the solid substance obtained after opening the kettle, separate at 9000 rpm for 4 min, and wash multiple times until the pH value reaches 8. Dry in a vacuum drying oven at 80 °C for 15 h to obtain a solid white powder.

[0086] S4. Calcinate the obtained powder at 600 °C for 8 h to obtain the hierarchical porous molecular sieve NaY-2.

[0087] The above soluble starch is potato starch.

[0088] Example 3

[0089] S1. Add 0.15 mL of deionized water to 13.9 mL of highly alkaline sodium aluminate solution, and while stirring, gradually add 20.11 mL of water glass drop by drop (the dosages of the highly alkaline sodium aluminate solution and water glass are such that the molar ratio of Al 2 O 3 , Na 2 O and SiO 2 is 1:13:17; the pH value of the obtained mixed solution is 10.6; the total dosage of water is such that the weight ratio of water to SiO 2 in the water glass is 71:1 (the total dosage of water includes the added deionized water, the water contained in the highly alkaline sodium aluminate solution, and the water contained in the water glass), and continue to stir at 25 °C for 80 min. Age at 30 °C for 24 h to obtain a seed directing agent.

[0090] Prepare 4.3 mol / L Al(OH) 3 solution and 10.4 mol / L NaOH solution respectively, mix and stir them until the solution is clear and transparent to obtain 1.33 mL of low-alkaline sodium aluminate solution with a concentration of 6.96 mol / L and a pH value of 11.8. Under the condition of a 70 °C oil bath, mix and stir the low-alkaline sodium aluminate solution, 0.9 mol / L Al 2 (SO 4 ) 3 solution, 25.6 mL of water glass and 12.3 mL of water for 3 h to obtain a precursor mixture with a pH value of 11. Among them, the dosages of the low-alkaline sodium aluminate solution, Al 2 (SO 4 ) 3 solution, and water glass are such that the molar ratio of Al 2 O 3 , Na 2 O, SiO 2 is 2:11:32; the total dosage of water is such that the weight ratio of water to SiO 2 in the water glass is 8.9:1 (the total dosage of water includes the added deionized water, the water contained in the low-alkaline sodium aluminate solution, Al2 (SO 4 ) 3 (Water contained in the solution and water glass).

[0091] S2. Under the condition of a 70 °C oil bath, add soluble starch to the precursor mixture and continue stirring for 8 h. The dosage of soluble starch is such that the weight ratio of SiO 2 to soluble starch is 12:1. At room temperature, based on the total weight of the soluble starch and the precursor mixture, add 7 wt% of the seed directing agent and stir for 0.8 h, then hydrothermally crystallize at 98 °C for 44 h.

[0092] S3. Centrifuge and wash the solid substance obtained after opening the autoclave, separate at 8000 rpm for 5 min, and wash multiple times until the pH value is 7.6. Dry in a vacuum drying oven at 85 °C for 12 h to obtain a solid white powder.

[0093] S4. Calcinate the obtained powder at 550 °C for 13 h to obtain the hierarchical pore molecular sieve NaY-3.

[0094] The above-mentioned soluble starch is tapioca starch.

[0095] Example 4

[0096] Prepare the molecular sieve according to the method of Example 1, except that when preparing the precursor mixture, the dosages of the aluminum source and the silicon source are different. Specifically, in S1, use "low-alkali sodium aluminate solution, Al 2 (SO 4 ) 3 solution, and the dosages of water glass are such that the molar ratio of Al 2 O 3 , Na 2 O, SiO 2 is 1:21:10" to replace "low-alkali sodium aluminate solution, Al 2 (SO 4 ) 3 solution, and the dosages of water glass are such that the molar ratio of Al 2 O 3 , Na 2 O, SiO 2 is 1:3:8". Obtain the hierarchical pore molecular sieve NaY-4.

[0097] Example 5

[0098] Prepare the molecular sieve according to the method of Example 1, except that when the soluble starch reacts with the precursor mixture, the dosage of the soluble starch is different. Specifically, in S2, use "the dosage of soluble starch is such that the weight ratio of SiO 2 to soluble starch is 15.5:1" to replace "the dosage of soluble starch is such that the weight ratio of SiO2 The mass ratio with soluble starch is 3:1”. Mesoporous molecular sieve NaY-5 is obtained.

[0099] Example 6

[0100] Prepare the molecular sieve according to the method of Example 1, except that when preparing the seed directing agent, the aging temperature is different. Specifically, in S1, replace “aging at 30°C for 18 h to obtain the seed directing agent” with “aging at 42°C for 18 h to obtain the seed directing agent”. Mesoporous molecular sieve NaY-6 is obtained.

[0101] Example 7

[0102] Prepare the molecular sieve according to the method of Example 1, except that when preparing the precursor mixture and the reaction conditions of soluble starch and the precursor mixture are different. Specifically, in S1 and S2, replace “under the oil bath condition at 80°C” with “under the oil bath condition at 55°C” respectively. Mesoporous molecular sieve NaY-7 is obtained.

[0103] Example 8

[0104] Prepare the molecular sieve according to the method of Example 1, except that the calcination temperature of the solid white powder is different. Specifically, in S4, replace “calcine the obtained powder at 600°C for 10 h” with “calcine the obtained powder at 400°C for 10 h”. Mesoporous molecular sieve NaY-8 is obtained.

[0105] Example 9

[0106] Prepare the molecular sieve according to the method of Example 1, except that when preparing the precursor mixture, the amount of water used is different. Specifically, in S1, replace “Mix the low-alkali sodium aluminate solution, 3.77 mol / L Al 2 (SO 4 ) 3 solution, 10.67 mL of water glass and 15 mL of water and stir for 1.5 h; the total amount of water used makes the weight ratio of water to SiO 2 in water glass 21:1” with “Mix the low-alkali sodium aluminate solution, 3.77 mol / L Al 2 (SO 4 ) 3 solution, 10.67 mL of water glass and 6.3 mL of water and stir for 1.5 h; the total amount of water used makes the weight ratio of water to SiO 2 in water glass 7.4:1”. Mesoporous molecular sieve NaY-9 is obtained.

[0107] Comparative Example 1

[0108] The molecular sieve was prepared according to the method of Example 1, except that the stirring time after adding soluble starch to the precursor mixture was different. Specifically, in S2, "continuously stir for 16 h after adding soluble starch to the precursor mixture under an 80 °C oil bath condition" was used to replace "continuously stir for 12 h after adding soluble starch to the precursor mixture under an 80 °C oil bath condition". The hierarchical pore molecular sieve NaY-10 was obtained.

[0109] Comparative Example 2

[0110] The molecular sieve was prepared according to the method of Example 1, except that when preparing the precursor mixture, the feeding order was changed to add the seed directing agent, silicon source, and aluminum source to the system simultaneously. Specifically, in S1, "under an 80 °C oil bath condition, mix and stir 9 wt% seed directing agent, sodium metaaluminate solution with low alkalinity, 3.77 mol / L Al 2 (SO 4 ) 3 solution, 10.67 mL water glass, and 6.3 mL water for 1.5 h" was used to replace "under an 80 °C oil bath condition, mix and stir sodium metaaluminate solution with low alkalinity, 3.77 mol / L Al 2 (SO 4 ) 3 solution, 10.67 mL water glass, and 6.3 mL water for 1.5 h", and no seed directing agent was added in S2. The molecular sieve NaY-11 was obtained.

[0111] Comparative Example 3

[0112] The molecular sieve was prepared according to the method of Example 1, except that when preparing the precursor mixture, the seed directing agent, silicon source, aluminum source, and soluble starch were added to the system simultaneously. Specifically, in S1, "under an 80 °C oil bath condition, mix and stir 9 wt% seed directing agent, sodium metaaluminate solution with low alkalinity, 3.77 mol / L Al 2 (SO 4 ) 3 solution, 10.67 mL water glass, 6.3 mL water, and soluble starch for 12 h, and the amount of soluble starch was such that the weight ratio of SiO 2 to soluble starch was 3:1" was used to replace "under an 80 °C oil bath condition, mix and stir sodium metaaluminate solution with low alkalinity, 3.77 mol / L Al 2 (SO 4 ) 3 solution, 10.67 mL water glass, and 6.3 mL water for 1.5 h", and no seed directing agent and soluble starch were added in S2. The molecular sieve NaY-12 was obtained.

[0113] Comparative Example 4

[0114] The molecular sieve was prepared according to the method of Example 1, except that the template agent (soluble starch) was not added. Specifically, in S2, at room temperature, based on the total weight of the precursor mixture, 9 wt% of the seed directing agent was added and stirred for 1 h, and hydrothermal crystallization was carried out at 100 °C for 48 h. The molecular sieve NaY-13 was obtained.

[0115] Comparative Example 5

[0116] The molecular sieve was prepared according to the method of Example 1, except that glucose was used as the template agent. Specifically, in S2, "add glucose to the precursor mixture and continue stirring for 12 h, and the amount of glucose used makes the weight ratio of SiO 2 and soluble starch 3:1" was used to replace "add soluble starch to the precursor mixture and continue stirring for 12 h, and the amount of soluble starch used makes the weight ratio of SiO 2 and soluble starch 3:1". The molecular sieve NaY-14 was obtained.

[0117] Test Example

[0118] The crystallization of the molecular sieve was determined using an XRD multi-functional X-ray diffractometer, and the specific surface area and pore size distribution of the molecular sieve were determined using an ASAP 2460 type specific surface area - pore size analyzer. The results of the relative crystallinity, the total volume of pores in the molecular sieve, and the total volume of mesopores in the molecular sieve prepared in each example and each comparative example after fitting calculation are shown in Table 1.

[0119] Figure 1 Figure for the XRD of the prepared hierarchical pore NaY-1 and traditional NaY (NaY-13). It can be seen from Figure 1 that compared with the NaY-13 molecular sieve, the peak intensity of the hierarchical pore NaY-1 molecular sieve is slightly higher, but the relative crystallinity of the NaY-1 molecular sieve and the NaY-13 molecular sieve after fitting calculation is not much different, and the relative crystallinity of the NaY-1 molecular sieve is 98%.

[0120] Figure 2 Figure for the pore size of the prepared hierarchical pore NaY-1 molecular sieve and traditional NaY (NaY-13) molecular sieve. It can be seen from Figure 2It can be seen that the volume of mesopores with a pore size of 3 - 10 nm in NaY-13 zeolite accounts for 22.1% of the total mesopore volume, and the volume of mesopores with a pore size of 10 - 50 nm accounts for 77.9% of the total mesopore volume; in NaY-1 zeolite, the volume of mesopores with a pore size of 3 - 10 nm accounts for 21% of the total mesopore volume, which is 30.24 times higher than that of NaY-13 zeolite; the volume of mesopores with a pore size of 10 - 50 nm accounts for 75.6% of the total mesopore volume, which is 2.25 times higher than that of NaY-13 zeolite. Relatively speaking, the increase in the volume of mesopores with a pore size of 3 - 10 nm far exceeds the increase in the volume of mesopores with a pore size of 10 - 50 nm.

[0121] Figure 3 XRD patterns of the prepared hierarchical pore NaY-2 zeolite and traditional NaY (NaY-13) zeolite. From Figure 3 it can be seen that compared with NaY-13 zeolite, the peak intensity of the hierarchical pore NaY-2 zeolite is slightly higher, but the relative crystallinity of the NaY-2 zeolite obtained after fitting calculation is slightly lower than that of the NaY-13 zeolite, and the relative crystallinity of the NaY-2 zeolite is 92%.

[0122] Figure 4 Pore size diagrams of the prepared hierarchical pore NaY-2 zeolite and traditional NaY (NaY-13) zeolite. From Figure 4 it can be seen that the volume of mesopores with a pore size of 3 - 10 nm in NaY-13 zeolite accounts for 22.1% of the total mesopore volume, and the volume of mesopores with a pore size of 10 - 50 nm accounts for 77.9% of the total mesopore volume; in NaY-2 zeolite, the volume of mesopores with a pore size of 3 - 10 nm accounts for 24.4% of the total mesopore volume, which is 13.83 times higher than that of NaY-13 zeolite; the volume of mesopores with a pore size of 10 - 50 nm accounts for 75.6% of the total mesopore volume, which is 0.36 times higher than that of NaY-13. Relatively speaking, the increase in the volume of mesopores with a pore size of 3 - 10 nm far exceeds the increase in the volume of mesopores with a pore size of 10 - 50 nm.

[0123] Figure 5 XRD patterns of the prepared hierarchical pore NaY-3 zeolite and traditional NaY (NaY-13) zeolite. From Figure 5 it can be seen that compared with NaY-13 zeolite, the peak intensity of the hierarchical pore NaY-3 zeolite is slightly higher, but the relative crystallinity of the NaY-3 zeolite obtained after fitting calculation is slightly lower than that of the NaY-13 zeolite, and the relative crystallinity of the NaY-3 zeolite is 89%.

[0124] Figure 6 Pore size diagrams of the prepared hierarchical pore NaY-3 zeolite and traditional NaY (NaY-13) zeolite. FromFigure 6 It can be seen that the volume of mesopores with pore diameters of 3 - 10 nm in NaY-13 molecular sieve accounts for 22.1% of the total mesopore volume, and the volume of mesopores with pore diameters of 10 - 50 nm accounts for 77.9% of the total mesopore volume; in NaY-3 molecular sieve, the volume of mesopores with pore diameters of 3 - 10 nm also accounts for 22.1% of the total mesopore volume, but compared with NaY-13 molecular sieve, it is increased by 34.77 times; the volume of mesopores with pore diameters of 10 - 50 nm accounts for 77.9% of the total mesopore volume, and compared with NaY-13 molecular sieve, it is increased by 2.71 times. Relatively speaking, the increase in the volume of mesopores with pore diameters of 3 - 10 nm far exceeds the increase in the volume of mesopores with pore diameters of 10 - 50 nm.

[0125] Table 1

[0126]

[0127]

[0128] As can be seen from the data in Table 1, the molecular sieves provided by the present invention prepared in Examples 1 - 9 have relatively high relative crystallinity, relatively high specific surface area, relatively high total pore volume and relatively high mesopore volume. In Comparative Example 1, the stirring time after adding soluble starch to the precursor mixture was extended, and in Comparative Examples 2 and 3, the feeding order during the preparation of the precursor mixture was changed, and the molecular sieves prepared had very low relative crystallinity or formed an amorphous structure; Comparative Example 4 was a traditional molecular sieve without adding a template agent. Although the relative crystallinity was as high as 100%, the mesopore volume was significantly reduced compared with Examples 1 - 9; in Comparative Example 5, glucose was used as the template agent, and compared with Examples 1 - 9, not only the relative crystallinity was reduced, but the mesopore volume was also significantly reduced. This shows that compared with the traditional molecular sieve NaY-13, the molecular sieve prepared by the method of the present invention can not only maintain relatively high relative crystallinity, but also effectively increase the mesopore volume of the molecular sieve.

[0129] In addition, in Example 4, the amounts of the aluminum source and the silicon source were changed when preparing the precursor mixture; in Example 5, the amount of soluble starch was changed; in Example 6, the aging temperature when preparing the seed directing agent was changed. Compared with Example 1, both the relative crystallinity and the mesopore volume decreased; in Example 7, the temperatures when preparing the precursor mixture and when the soluble starch reacted with the precursor mixture were changed; in Example 8, the calcination temperature of the solid after crystallization was changed. Compared with Example 1, although the relative crystallinity did not decrease significantly, the mesopore volume decreased; in Example 9, the amount of water when preparing the precursor mixture was changed. Compared with Example 1, both the relative crystallinity and the mesopore volume decreased. This shows that when the amounts of the aluminum source and the silicon source, the amount of soluble starch, the aging temperature when preparing the seed directing agent, the temperatures when preparing the precursor mixture and when the soluble starch reacts with the precursor mixture, the calcination temperature of the solid after crystallization, and the amount of water when preparing the precursor mixture meet the preferred conditions, the relative crystallinity and the mesopore volume of the prepared molecular sieve can be further improved. Examples 1-3 that meet the preferred conditions can not only keep the Y-type molecular sieve with a relatively high relative crystallinity (80-100%), but also greatly increase the mesopore volume in the molecular sieve. Among them, the volume of the mesopores with a pore diameter of 3-10 nm increased most significantly, far higher than the volume increase of the mesopores with a pore diameter of 10-50 nm.

[0130] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A hierarchical pore Y zeolite, characterized in that, The total pore volume of the molecular sieve is 0.3 - 0.45 cm 3 / g; wherein, the total pore volume of the mesopores with a pore diameter of 3 - 50 nm in the molecular sieve is 0.12 - 0.35 cm 3 / g; the relative crystallinity of the molecular sieve is 65 - 100%.

2. The preparation method according to claim 1, characterized in that, In the molecular sieve, the total volume of mesopores with a pore diameter of 3 - 10 nm is 0.04 - 0.1 cm 3 / g, preferably 0.07 - 0.1 cm 3 / g; the total volume of mesopores with a pore diameter of 10 - 50 nm is 0.08 - 0.25 cm 3 / g, preferably 0.16 - 0.25 cm 3 / g; Preferably, the specific surface area of the molecular sieve is 450 - 700 m 2 / g; Preferably, the relative crystallinity of the zeolite is 80-100%.

3. A preparation method of a hierarchical pore Y zeolite, characterized in that, The preparation method includes the following steps: S1. In the presence of a first solvent, an aluminum source and a silicon source are mixed under alkaline conditions for a first reaction to obtain a precursor mixture; S2. The precursor mixture and water-soluble starch are mixed for a second reaction to obtain a mixture after the second reaction; the seed directing agent and the mixture after the second reaction are mixed for crystallization; wherein, the time of the second reaction is less than or equal to 15 h; S3. The solid phase product obtained by the crystallization is washed and dried; S4. The solid obtained in S3 is calcined.

4. The preparation method according to claim 3, characterized in that, In S1, the aluminum source is selected from water-soluble aluminum salts and / or water-soluble meta-aluminates, preferably selected from sodium meta-aluminate and / or aluminum sulfate; Preferably, the silicon source is a silicate, preferably sodium silicate; Preferably, the first solvent is water.

5. The preparation method according to claim 4, characterized in that, In S1, the amount of the aluminum source is based on the molar amount of Al 2 O 3 , and the amount of the silicon source is based on the molar amount of SiO 2 . When performing the first reaction, the amounts of the aluminum source and the silicon source are such that the molar ratio of Al 2 O 3 to SiO 2 is (1 - 20) : (1 - 20); Preferably, the amount of the first solvent is such that the weight ratio of the first solvent to SiO in the silicon source is (1-20):1; 2 ​ Preferably, the first reaction is carried out under the condition of a pH value of 9-14; Preferably, the temperature of the first reaction is 60-85 °C, and the time is 0.5-3 h.

6. The preparation method according to claim 4 or 5, characterized in that, When carrying out the second reaction, the dosage of the water-soluble starch is such that the weight ratio of SiO in the silicon source 2 to the water-soluble starch is (1-15):1; Preferably, the temperature of the second reaction is 60-85 °C, and the time is 3-12 h.

7. The preparation method according to any one of claims 3-6, characterized in that, In S2, the preparation method of the seed directing agent includes: in the presence of a second solvent, sodium meta-aluminate and sodium silicate are mixed under alkaline conditions for a third reaction, and then aging is carried out; Preferably, the amount of sodium aluminate is based on the total molar amount of Al 2 O 3 and Na 2 O. The amount of sodium silicate is based on the total molar amount of Na 2 O and SiO 2 . When performing the third reaction, the amounts of sodium aluminate and sodium silicate are such that the molar ratio of Al 2 O 3 , Na 2 O and SiO 2 is (1 - 30):(1 - 30):(1 - 30); Preferably, the amount of the second solvent is such that the weight ratio of the second solvent to SiO in sodium silicate is (50 - 80):1; 2 ​ Preferably, the second solvent is water; Preferably, the third reaction is carried out under the condition of a pH value of 9-11; Preferably, the temperature of the third reaction is 15-25 °C, and the time is 15-120 min; Preferably, the temperature of the aging is 20-40 °C, and the time is 10-24 h.

8. The preparation method according to any one of claims 3-7, characterized in that, In S2, based on the total weight of the mixture after the second reaction, the dosage of the seed directing agent is 5-30 wt%; Preferably, the temperature of the crystallization is 90-110 °C, and the time is 24-60 h.

9. The preparation method according to any one of claims 3-8, characterized in that, In S3, the washing conditions are such that the pH value of the washed material is 7.2-8.2; Preferably, the drying temperature is 50-100 °C, and the time is 10-24 h; Preferably, in S4, the calcination temperature is 500-650 °C, and the time is 5-20 h.

10. A hierarchical pore Y zeolite prepared by the preparation method according to any one of claims 3-9.

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