CN111086995A - Method for preparing high-crystallinity Y-type molecular sieve containing mesopores - Google Patents
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Abstract
A method for preparing a high-crystallinity Y-type molecular sieve containing mesopores is characterized by comprising the following steps: mixing and hydrolyzing a 2, 3-epoxypropyltrimethylammonium chloride modified cationic starch template agent with the substitution degree of 0.01-10% with an alkali source and water to obtain a hydrolysate; and adding the reactive silicon-aluminum gel into the hydrolysate to obtain an initial mixture, fully and uniformly mixing the initial mixture to obtain a gel mixture, and performing dynamic crystallization in a closed crystallization kettle. The preparation method provided by the invention breaks through the technical barrier that the high-crystallinity NaY molecular sieve cannot be synthesized by conventional dynamic crystallization.
Description
Technical Field
The invention relates to a method for preparing a mesoporous high-crystallinity Y-type molecular sieve.
Background
Conventional industrially applicable Y-type molecular sieves mainly include HY with a relatively high silica to alumina ratio, dealuminated ultrastable USY and rare earth exchanged REY or REUSY for catalytic cracking reactions. Fluid Catalytic Cracking (FCC) is an important process for the secondary processing of crude oil. With the heavy and inferior nature of crude oil, the excellent properties of the medium pore containing high crystallinity Y-type molecular sieve are gradually manifested. The mesoporous and high-crystallinity Y-type molecular sieve has a micropore and mesoporous double-pore model pore distribution structure, combines the advantages of a mesoporous material (excellent diffusion performance) and a microporous zeolite molecular sieve (strong acidity, high stability and the like), and is considered as a novel catalytic material for improving the heavy oil macromolecule conversion capacity.
CN1349929A discloses a high crystallinity molecular sieve containing mesopores, which is characterized in that the primary and secondary structural units of Y-type zeolite are introduced into the pore wall of the molecular sieve, so that it has the basic structure of conventional Y-type molecular sieve, but its improvement of acidity and hydrothermal stability is still very limited, and can not meet the use requirement of FCC.
CN103214003A discloses a mesoporous Y-type molecular sieve, which is characterized in that amphiphilic cationic starch N, N-dimethyl-N- [ 3- (trimethoxysilane) propyl ] octadecyl ammonium chloride (TPOAC) is used as a mesoporous template agent to guide the synthesis of the mesoporous Y-type molecular sieve.
CN106927479A discloses a method for preparing a mesoporous Y-type molecular sieve, which is characterized in that polyacrylamide is added into a crystallization liquid, and the pore size distribution is concentrated at 1.5-3 nm.
CN107344720A discloses a method for preparing a mesoporous Y-type molecular sieve, which is characterized in that hydrothermal crystallization treatment is performed in the presence of an organic template agent, and then roasting is performed in a low-temperature oxygen-rich environment. The molecular sieve has good thermal stability and hydrothermal stability, and particularly, the prepared hydrocracking catalyst has good catalytic activity and target product selectivity.
CN107555446A discloses a method for preparing a hierarchical pore Y-type molecular sieve, which is characterized in that under the mixed treatment of a co-structure directing agent and a template agent, the obtained hierarchical pore molecular sieve has high relative crystallinity, regular mesopore channels, and uniform mesopore diameter distribution, wherein micropore channels and mesopore channels penetrate through the hierarchical pore molecular sieve.
Disclosure of Invention
The inventor of the invention unexpectedly discovers on the basis of a large number of tests that when a hydrolyzed cationic starch template with specific substitution degree is added in the synthesis process of the NaY molecular sieve and dynamic crystallization is carried out in a rotary oven, the Y-type molecular sieve with medium pores and high crystallinity can be obtained, and the technical barrier that the conventional dynamic crystallized NaY molecular sieve can not synthesize high crystallinity is broken through. Based on this, the present invention was made.
The invention aims to provide a method for preparing a mesoporous-containing high-crystallinity Y-type molecular sieve, which breaks through the technical barrier and can greatly improve the production efficiency, has short flow and low cost.
The invention provides a method for preparing a mesoporous high-crystallinity Y-type molecular sieve, which is characterized by comprising the following steps:
(1) preparing a crystallization guiding agent: according to Al2O3:(1～35)SiO2:(10～35)Na2O:(180～400)H2Mixing a silicon source, an aluminum source and water according to the molar ratio of O, and then standing and aging at 0-80 ℃ for 0.5-60 h to obtain a crystallization directing agent;
(2) 2, 3-epoxypropyltrimethylammonium chloride modified cationic starch template with the substitution degree of 0.01-10%, an alkali source and water are mixed according to the mass ratio of (0.1-5): (0.1-3): (1-100), and hydrolyzing at 30-150 ℃ to obtain a hydrolysate;
(3) according to Al2O3:(1～20)SiO2:(1～10)Na2O:(120～300)H2Mixing a silicon source, an aluminum source and water for 0.5-5 hours to obtain reactive silicon-aluminum gel, and adding the hydrolysate to obtain an initial mixture, wherein the addition amount of the hydrolysate is 0.01-0.8 of the silicon source in the reactive silicon-aluminum gel, and the silicon source in the reactive silicon-aluminum gel is calculated by the cationic starch template agent;
(4) and (3) fully and uniformly mixing the initial mixture obtained in the step (3) to obtain a gel mixture, carrying out dynamic crystallization in a closed crystallization kettle at the temperature of 60-180 ℃ for 0.5-60 h, and recovering the product.
The preparation method provided by the invention breaks through the technical barrier that the conventional dynamic crystallized NaY molecular sieve cannot synthesize high crystallinity. The 2, 3-epoxypropyl trimethyl ammonium chloride modified cationic starch template agent used in the invention is easy to obtain, has low price of about 5000 per ton, is low in dosage, and is easy to separate from a bulk phase (based on a filtrate obtained by filtering after synthesis). The Y-type molecular sieve prepared by the method has obvious pore characteristics, high crystallinity compared with the conventional NaY, simple preparation method and high feasibility, and has wide application prospect in the field of macromolecular catalysis limited by diffusion.
Drawings
FIG. 1 is an XRD spectrum of a Y-type molecular sieve sample prepared by the method of example 1 of the present invention and a NaY comparative sample obtained in comparative example 3.
FIG. 2 is a low temperature nitrogen physisorption-desorption curve of a Y-type molecular sieve sample prepared by the method of example 1 of the present invention and a NaY comparative sample obtained in comparative example 3.
Detailed Description
A process for preparing a high crystallinity Y-type molecular sieve containing mesopores, characterized in that the preparation process comprises:
(1) preparing a crystallization guiding agent: according to Al2O3:(1～35)SiO2:(10～35)Na2O:(180～400)H2Mixing a silicon source, an aluminum source and water according to the molar ratio of O, and then standing and aging at 0-80 ℃ for 0.5-60 h to obtain a crystallization directing agent;
(2) 2, 3-epoxypropyltrimethylammonium chloride modified cationic starch template with the substitution degree of 0.01-10%, an alkali source and water are mixed according to the mass ratio of (0.1-5): (0.1-3): (1-100), and hydrolyzing at 30-150 ℃ to obtain a hydrolysate;
(3) according to Al2O3:(1～20)SiO2:(1～10)Na2O:(120～300)H2Mixing a silicon source, an aluminum source and water for 0.5-5 hours to obtain reactive silicon-aluminum gel, and adding the hydrolysate to obtain an initial mixture, wherein the addition amount of the hydrolysate is 0.01-0.8 of the silicon source in the reactive silicon-aluminum gel, and the silicon source in the reactive silicon-aluminum gel is calculated by the cationic starch template agent;
(4) and (3) fully and uniformly mixing the initial mixture obtained in the step (3) to obtain a gel mixture, carrying out dynamic crystallization in a closed crystallization kettle at the temperature of 60-180 ℃ for 0.5-60 h, and recovering the product.
In the invention, the crystallinity of the Y-type molecular sieve containing mesopores and high crystallinity is more than 80 percent. Compared with the pore volume (Vmeso convention) of mesopores (referring to pores of 2-50 nm) of the NaY molecular sieve obtained by the conventional method, the pore volume (Vmeso) of the mesopores is larger, and the Vmeso/VmesoGeneral of≥2。
In the invention, the silicon source is one or a mixture of more of ethyl silicate, water glass, silica gel, sodium silicate and silica gel.
In the invention, the aluminum source is one or a mixture of more of sodium metaaluminate, aluminum sulfate, aluminum isopropoxide, tert-butyl aluminum and aluminum oxide.
In the invention, the alkali source is sodium metaaluminate, NaOH and NH4One or a mixture of more of OH and water glass.
The invention relates to a method for preparing a Y-type molecular sieve by using a template agent. The templating agent of the present invention should have a strong interaction with the silica or silica alumina species. Considering that the synthesis of zeolite crystals is generally accomplished under alkaline conditions, whereas silicon species are generally negatively charged under alkaline conditions, the positive charge of the cationic starch selected in the present invention is effective in increasing the interaction of the cationic starch with the silicon species. In the invention, cationic starch with different degrees of substitution modified by 2, 3-epoxypropyltrimethylammonium chloride is used as a template agent, and the generated template effect not only promotes the improvement of the crystallinity of the Y-type molecular sieve, but also can form a certain mesopore, thereby playing a dual-guiding role. The precursor starch of the template agent can be one or a mixture of corn (recorded as YZC series), cassava (recorded as YZA series) and guar gum (recorded as YZG series), and the substitution degree is 0.01-10%, preferably 0.1-5%.
The 2, 3-epoxypropyltrimethylammonium chloride modified cationic starch template agent can be prepared by the following preparation method: adding alkali into 2, 3-epoxypropyl trimethyl ammonium chloride to form epoxy compound, and etherifying with starch under alkaline condition. The reaction is generally divided into a wet method and a dry method, wherein the wet method has uniform reaction, low efficiency and higher cost; the dry method has low cost and more impurities, and mainly needs to solve the problem of uniformity of mixing of starch and reagents.
The substitution degree of the cationic starch is measured by a Kjeldahl method or an ammonia-sensitive electrode potentiometric titration method.
In the invention, in the process of preparing the crystallization guiding agent, the mol ratio of the guiding agent is Al2O3:(10～20)SiO2:(10～20)Na2O:(240～360)H2And O, wherein the aging temperature is 20-60 ℃, and the aging time is 5-50 h.
In the invention, the mass ratio of the cationic starch template agent to the alkali source to the water is preferably (0.1-3): (1-6): (1-80), the hydrolysis is preferably carried out at 30-120 ℃.
The reactive silicon-aluminum gel Al2O3:(4～15)SiO2:(1～5)Na2O:(150～280)H2The mole ratio of O and the addition amount of the template agent are preferably 0.01-0.5 of the mole ratio of a silicon source in the reactive silicon-aluminum gel, wherein the hydrolysis product is calculated by the cationic starch template agent, and the silicon source in the reactive silicon-aluminum gel is calculated by silicon oxide.
The crystallization temperature is 70-130 ℃, and the dynamic crystallization time is 10-50 h.
The dynamic crystallization can be carried out in a rotary oven or in a dynamic crystallization mode with a closed crystallization kettle with stirring and heating. The invention adopts the 2, 3-epoxypropyl trimethyl ammonium chloride modified cationic starch template agent with the degree of substitution of 0.01-10 percent and the dynamic crystallization technology, and breaks through the technical barrier that the conventional dynamic crystallization NaY molecular sieve can not synthesize high crystallinity. For example, the conventional dynamic crystallization crystallinity is only 76.7 percent (comparative example 2), while the technology of the invention can reach 108.7 percent (example 1), and the result shows that the technology breaks through the technical barrier of low crystallinity of the conventional dynamic crystallization NaY molecular sieve.
Preferably, the crystallization temperature is 70-130 ℃, and the standing crystallization time is 10-50 h. The process of recovering the product generally comprises filtration, drying and calcination, the operating parameters of which are known to those skilled in the art, such as time and temperature, and will not be described in detail.
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.
In each example, the crystalline structure of the product was determined by X-ray diffraction (XRD) and a spectrum with 2 theta angles of 5 to 35 degrees was recorded. The specific surface and pore structure parameters of the product are obtained by low-temperature nitrogen adsorption and desorption measurement.
Example 1
According to Al2O3:15SiO2:16.5Na2O:320H2And (3) adding 30ml of water glass (modulus 3.3) into 20.8ml of sodium metaaluminate solution according to the molar ratio of O, stirring and dissolving, and then aging at 45 ℃ for 5 hours to obtain the crystallization directing agent.
2g of YZA-2 cationic starch (with the degree of substitution of 0.5%) is taken out of 60g of water, 1g of NaOH is added, the mixture is stirred uniformly, the temperature is raised to 60 ℃, and the mixture is stirred at constant temperature for 1 hour for hydrolysis treatment.
Adding 18g of guiding agent into 65ml of water glass (modulus 3.3), stirring for 0.5h, adding YZA-2 cationic starch (substitution degree 0.5%) aqueous solution after hydrolysis treatment, stirring for 1h, adding 40ml of aluminum sulfate and 18ml of sodium metaaluminate, continuing stirring for 1h after the addition is finished, finally putting the mixture into a stainless steel crystallization kettle, sealing, dynamically crystallizing in a rotary oven at 95 ℃ for 28h, filtering, washing, drying a filter cake in an oven at 120 ℃ for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve with high mesopore crystallinity.
The crystallinity and BET data are shown in table 1.
The XRD spectrum is shown as a Meso-NaY curve in figure 1, and the consistent state with the conventional NaY peak form can be seen from figure 1, and other miscellaneous peaks do not appear, which indicates that the Y-type molecular sieve is prepared and has higher crystallinity.
The low temperature nitrogen physisorption-desorption curve is shown in fig. 2, and it can be seen from fig. 2 that there is a clear and large hysteresis loop compared to conventional NaY, indicating a significant mesoporous character.
Comparative example 1
This comparative example illustrates the comparative preparation procedure and results of adding unhydrolyzed cationic starch directly to the synthesis system.
The difference from example 1 is that the cationic starch (degree of substitution 0.5%) of comparative example YZA-2 template was not hydrolyzed.
According to Al2O3:15SiO2:16.5Na2O:320H2And (3) adding 30ml of water glass (modulus 3.3) into 20.8ml of sodium metaaluminate solution according to the molar ratio of O, stirring and dissolving, and then aging at the temperature of 30 ℃ for 20 hours to obtain the crystallization directing agent.
Adding 24g of the directing agent into 120ml of water glass (modulus 3.3), stirring for 1h, adding 2g of YZA-2 cationic starch (with the degree of substitution of 0.5%) and 60g of water into a synthesis system, stirring for 1h, adding 50ml of aluminum sulfate and 24ml of sodium metaaluminate, continuing stirring for 1h after the addition is finished, finally putting the mixture into a stainless steel crystallization kettle, sealing, dynamically crystallizing for 24h in a rotary oven at 100 ℃, filtering, washing, drying a filter cake in the oven at 120 ℃ for 8h, and roasting for 2h at 550 ℃ to obtain the Y-type molecular sieve with the mesopore and high crystallinity.
The crystallinity and BET data are shown in table 1.
Comparative example 2
This comparative example illustrates the preparation process and results of dynamic crystallization without the addition of cationic starch templating agent.
The difference from example 1 is that the dynamic crystallization synthesis was carried out without adding YZA-2 cationic starch (degree of substitution 0.5%) as a template.
According to Al2O3:15SiO2:16.5Na2O:320H2And (3) adding 30ml of water glass (modulus 3.3) into 20.8ml of sodium metaaluminate solution according to the molar ratio of O, stirring and dissolving, and then aging at the temperature of 30 ℃ for 20 hours to obtain the crystallization directing agent.
And adding 24g of the directing agent into 120ml of water glass (modulus 3.3), stirring for 1 hour, adding 60g of water into a synthesis system, stirring for 1 hour, adding 50ml of aluminum sulfate and 24ml of sodium metaaluminate, continuing stirring for 1 hour after the addition is finished, finally placing the mixture into a stainless steel crystallization kettle, sealing, dynamically crystallizing in a rotary oven at 100 ℃ for 24 hours in the oven, filtering, washing, drying a filter cake in the oven at 120 ℃ for 8 hours, and roasting at 550 ℃ for 2 hours to obtain the Y-type molecular sieve with the mesopores and high crystallinity.
The crystallinity and BET data are shown in table 1.
Comparative example 3
This comparative example illustrates the preparation process and results of static crystallization of a conventional NaY type molecular sieve.
The difference from example 1 is that static crystallization synthesis was carried out without adding YZA-2 cationic starch (degree of substitution 0.5%) as a template.
According to Al2O3:15SiO2:16.5Na2O:320H2And (3) adding 30ml of water glass (modulus 3.3) into 20.8ml of sodium metaaluminate solution according to the molar ratio of O, stirring and dissolving, and then aging at the temperature of 30 ℃ for 20 hours to obtain the crystallization directing agent.
And adding 24g of the directing agent into 120ml of water glass (modulus 3.3), stirring for 1 hour, adding 60g of water into a synthesis system, stirring for 1 hour, adding 50ml of aluminum sulfate and 24ml of sodium metaaluminate, continuing stirring for 1 hour after the addition is finished, finally placing the mixture into a stainless steel crystallization kettle, sealing, standing and crystallizing in a 100 ℃ oven for 24 hours, filtering, washing, drying a filter cake in a 120 ℃ oven for 8 hours, and roasting at 550 ℃ for 2 hours to obtain the Y-type molecular sieve containing the mesopores and high crystallinity.
The crystallinity and BET data are shown in table 1. The XRD spectrum is shown as NaY curve in figure 1; the physical adsorption-desorption curve of the low-temperature desulfurization nitrogen is shown in the NaY curve in figure 2.
Example 2
According to Al2O3:15SiO2:16.5Na2O:320H2And (3) adding 30ml of water glass (modulus 3.3) into 20.8ml of sodium metaaluminate solution according to the molar ratio of O, stirring and dissolving, and then aging at the temperature of 30 ℃ for 20 hours to obtain the crystallization directing agent.
1g of YZA-1 cationic starch (with the degree of substitution of 1%) is put into 60g of water, 0.5g of NaOH is added, the mixture is stirred uniformly, the temperature is raised to 40 ℃, and the mixture is stirred at constant temperature for 1 hour for hydrolysis treatment.
Adding 12g of guiding agent into 50ml of water glass (modulus 3.3), stirring for 0.5h, adding YZA-1 cationic starch (substitution degree 1%) aqueous solution after hydrolysis treatment, stirring for 1h, adding 30ml of aluminum sulfate and 10ml of sodium metaaluminate, continuing stirring for 1h after the addition, finally putting the mixture into a stainless steel crystallization kettle, sealing, dynamically crystallizing in a rotary oven at 90 ℃ for 30h, filtering, washing, drying a filter cake in an oven at 120 ℃ for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve with the mesopores and the high crystallinity.
The crystallinity and BET data are shown in table 1. The XRD spectrum is characterized by the Meso-NaY curve of fig. 1, and the low temperature nitrogen physisorption-desorption curve is characterized by the Meso-NaY curve of fig. 2.
Example 3
According to Al2O3:15SiO2:16.5Na2O:320H2And (3) adding 30ml of water glass (modulus 3.3) into 20.8ml of sodium metaaluminate solution according to the molar ratio of O, stirring and dissolving, and then aging at the temperature of 30 ℃ for 20 hours to obtain the crystallization directing agent.
4g of YZA-3 cationic starch (the degree of substitution is 2%) is put into 60g of water, 3g of NaOH is added, the mixture is stirred uniformly, the temperature is raised to 100 ℃, and the mixture is stirred at constant temperature for 0.5h for hydrolysis treatment.
Adding 24g of guiding agent into 120ml of water glass (modulus 3.3), stirring for 1h, adding YZA-3 cationic starch (substitution degree 2%) aqueous solution after hydrolysis treatment, stirring for 1h, adding 50ml of aluminum sulfate and 24ml of sodium metaaluminate, continuing stirring for 1h after the addition, finally putting the mixture into a stainless steel crystallization kettle, sealing, dynamically crystallizing for 24h in a rotary oven at 100 ℃, filtering, washing, drying a filter cake in the oven at 120 ℃ for 8h, and roasting for 2h at 550 ℃ to obtain the Y-type molecular sieve with high mesopore crystallinity.
The crystallinity and BET data are shown in table 1. The XRD spectrum is characterized by the Meso-NaY curve of fig. 1, and the low temperature nitrogen physisorption-desorption curve is characterized by the Meso-NaY curve of fig. 2.
Example 4
According to Al2O3:15SiO2:16.5Na2O:320H2Molar ratio of O, 30ml of water glass (modulus 3.3) was added to 20.8ml of sodium metaaluminate solution, and stirredDissolving, and then aging at 45 ℃ for 5h to obtain the crystallization directing agent.
8g of YZA-4 cationic starch (degree of substitution 0.3%) was placed in 50g of water, and 10g of NH was added4OH, stirring evenly, heating to 100 ℃, and stirring at constant temperature for 0.5h for hydrolysis treatment.
And adding 20g of directing agent into 100g of silica gel, stirring for 1h, adding YZA-4 cationic starch (with the degree of substitution of 0.3%) aqueous solution after hydrolysis treatment, stirring for 1h, adding 45ml of aluminum sulfate and 20ml of sodium metaaluminate, continuing stirring for 1h after the addition, finally putting the mixture into a stainless steel crystallization kettle, sealing, dynamically crystallizing in a rotary oven at 110 ℃ for 20h, filtering, washing, drying a filter cake in the oven at 120 ℃ for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve with the mesopores and the high crystallinity.
The crystallinity and BET data are shown in table 1. The XRD spectrum is characterized by the Meso-NaY curve of fig. 1, and the low temperature nitrogen physisorption-desorption curve is characterized by the Meso-NaY curve of fig. 2.
Example 5
According to Al2O3:15SiO2:16.5Na2O:320H2And (3) adding 30ml of water glass (modulus 3.3) into 20.8ml of sodium metaaluminate solution according to the molar ratio of O, stirring and dissolving, and then aging at the temperature of 30 ℃ for 20 hours to obtain the crystallization directing agent.
2g of YZC-2 cationic starch (the degree of substitution is 0.8%) is put into 40g of water, 20ml of water glass is added, the mixture is stirred evenly, the temperature is raised to 110 ℃, and the mixture is stirred at constant temperature for 0.5h for hydrolysis treatment.
Adding 16g of guiding agent into 80ml of water glass (modulus 3.3), stirring for 1h, adding the YZC-2 cationic starch (substitution degree 0.8%) aqueous solution after hydrolysis treatment, stirring for 1h, adding 36ml of aluminum sulfate and 18ml of sodium metaaluminate, continuing stirring for 1h after the addition, finally putting the mixture into a stainless steel crystallization kettle, sealing, dynamically crystallizing for 18h in a rotary oven in an oven at 120 ℃, filtering, washing, drying a filter cake for 8h in the oven at 120 ℃, and roasting for 2h at 550 ℃ to obtain the Y-type molecular sieve with the mesopores and the high crystallinity.
The crystallinity and BET data are shown in table 1. The XRD spectrum is characterized by the Meso-NaY curve of fig. 1, and the low temperature nitrogen physisorption-desorption curve is characterized by the Meso-NaY curve of fig. 2.
Example 6
According to Al2O3:15SiO2:16.5Na2O:320H2And (3) adding 30ml of water glass (modulus 3.3) into 20.8ml of sodium metaaluminate solution according to the molar ratio of O, stirring and dissolving, and then aging at 45 ℃ for 5 hours to obtain the crystallization directing agent.
2g of YZG-2 cationic starch (with a degree of substitution of 5%) is put into 40g of water, 20ml of water glass is added, the mixture is stirred uniformly, the temperature is raised to 100 ℃, and the mixture is stirred at constant temperature for 1 hour for hydrolysis treatment.
Adding 16g of guiding agent into 80ml of water glass (modulus 3.3), stirring for 1h, adding the hydrolyzed YZG-2 cationic starch (substitution degree 5%) water solution, stirring for 1h, adding 36ml of aluminum sulfate and 18ml of sodium metaaluminate, continuing stirring for 1h after the addition is finished, finally putting the mixture into a stainless steel crystallization kettle, sealing, dynamically crystallizing in a rotary oven at 100 ℃ for 24h, filtering, washing, drying a filter cake in the oven at 120 ℃ for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve with the medium pores and high crystallinity.
The crystallinity and BET data are shown in table 1. The XRD spectrum is characterized by the Meso-NaY curve of fig. 1, and the low temperature nitrogen physisorption-desorption curve is characterized by the Meso-NaY curve of fig. 2.
Comparative example 4
This comparative example illustrates the comparative preparation procedure and results of adding unhydrolyzed cationic starch directly to the synthesis system.
The same as example 6, except that the cationic starch (degree of substitution 5%) of YZG-2 of this comparative example was not subjected to hydrolysis treatment.
According to Al2O3:15SiO2:16.5Na2O:320H2Adding 30ml of water glass (modulus 3.3) into 20.8ml of sodium metaaluminate solution, stirring for dissolving, and aging at 45 ℃ for 5 hours to obtain crystallization guideAnd (3) preparing.
Adding 16g of guiding agent into 80ml of water glass (modulus 3.3), stirring for 1h, then putting 2g of YZG-2 cationic starch (degree of substitution 5%) into 40g of water, adding the water into a synthesis system, stirring for 1h, then adding 36ml of aluminum sulfate and 18ml of sodium metaaluminate, continuing stirring for 1h after the addition is finished, finally putting the mixture into a stainless steel crystallization kettle, sealing, dynamically crystallizing for 24h in a rotary oven at 100 ℃, filtering, washing, drying a filter cake for 8h in an oven at 120 ℃, and roasting for 2h at 550 ℃ to obtain the Y-type molecular sieve with high mesopore crystallinity.
The crystallinity and BET data are shown in table 1.
Example 7
According to Al2O3:15SiO2:16.5Na2O:320H2And (3) adding 30ml of water glass (modulus 3.3) into 20.8ml of sodium metaaluminate solution according to the molar ratio of O, stirring and dissolving, and then aging at the temperature of 30 ℃ for 20 hours to obtain the crystallization directing agent.
6g of YZG-4 cationic starch (degree of substitution: 3%) was placed in 50g of water, and 10g of NH was added4OH, stirring evenly, heating to 110 ℃, and stirring at constant temperature for 0.5h for hydrolysis treatment.
And adding 20g of the directing agent into 100g of silica gel, stirring for 1h, adding the hydrolyzed YZG-4 cationic starch (with the degree of substitution of 3%) aqueous solution, stirring for 1h, adding 45ml of aluminum sulfate and 20ml of sodium metaaluminate, continuing stirring for 1h after the addition is finished, finally putting the mixture into a stainless steel crystallization kettle, sealing, dynamically crystallizing in a rotary oven at 100 ℃ for 24h, filtering, washing, drying a filter cake in the oven at 120 ℃ for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve with the mesopores and the high crystallinity.
The crystallinity and BET data are shown in table 1. The XRD spectrum is characterized by the Meso-NaY curve of fig. 1, and the low temperature nitrogen physisorption-desorption curve is characterized by the Meso-NaY curve of fig. 2.
TABLE 1
In Table 1, VmesoGeneral ofRefers to the mesopore volume of the molecular sieve obtained by the method of comparative example 3.
As can be seen from Table 1, FIG. 1 and FIG. 2, compared with conventional dynamic crystallized NaY (comparative example 2) and static crystallized NaY (comparative example 3), the crystallinity of conventional dynamic crystallized NaY (comparative example 2) is lower, while the crystallinity and mesopore characteristic of the Y-type molecular sieve containing mesopore and high crystallinity obtained after dynamic crystallization in a rotary oven are still higher and more obvious, the crystallinity and mesopore characteristic in examples 1 to 7 are both obviously higher than those in comparative examples 1 to 4, wherein the sample of example 1 is more preferable, which shows higher crystallinity and mesopore characteristic, which shows YZA-2 cationic starch (substitution degree of 0.5%) hydrolyzed under certain conditions, and then the participation process after dynamic crystallization in the rotary oven still exerts the template effect, not only promotes the improvement of the crystallinity of Y-type molecular sieve, but also forms certain mesopores, has double guiding function.
Claims (11)
1. A method for preparing a high-crystallinity Y-type molecular sieve containing mesopores is characterized by comprising the following steps:
(1) preparing a crystallization guiding agent: according to Al2O3:(1～35)SiO2:(10～35)Na2O:(180～400)H2Mixing a silicon source, an aluminum source and water according to the molar ratio of O, and then standing and aging at 0-80 ℃ for 0.5-60 h to obtain a crystallization directing agent;
(2) 2, 3-epoxypropyltrimethylammonium chloride modified cationic starch template with the substitution degree of 0.01-10%, an alkali source and water are mixed according to the mass ratio of (0.1-5): (0.1-3): (1-100), and hydrolyzing at 30-150 ℃ to obtain a hydrolysate;
(3) according to Al2O3:(1～20)SiO2:(1～10)Na2O:(120～300)H2Mixing a crystallization guiding agent, a silicon source, an aluminum source and water for 0.5-5 h to obtain reactive silicon-aluminum gel, and adding the hydrolysis product to obtain an initial mixture, wherein the addition amount of the hydrolysis product is equal to that of the reactive silicon-aluminum gelThe molar ratio of the medium silicon source is 0.01-0.8, wherein the hydrolysis product is calculated by a cationic starch template agent, and the silicon source in the reactive silicon-aluminum gel is calculated by silicon oxide;
(4) and (3) fully and uniformly mixing the initial mixture obtained in the step (3) to obtain a gel mixture, carrying out dynamic crystallization in a closed crystallization kettle at the temperature of 60-180 ℃ for 0.5-60 h, and recovering the product.
2. The method of claim 1, wherein the silicon source is one or more selected from the group consisting of ethyl silicate, water glass, silica gel, sodium silicate and silica gel.
3. The process of claim 1 wherein the aluminum source is one or a mixture of sodium metaaluminate, aluminum sulfate, aluminum isopropoxide, t-butyl aluminum and aluminum oxide.
4. The method of claim 1, wherein the source of alkalinity is sodium metaaluminate, NaOH, NH4One or a mixture of more of OH and water glass.
5. The method of claim 1 wherein said starch in said 2, 3-epoxypropyltrimethylammonium chloride modified cationic starch templating agent is derived from one or more of corn, tapioca, and guar gum.
6. The method according to claim 1, wherein said degree of substitution is from 0.1% to 5%.
7. The method of claim 1, wherein said crystallization director is prepared in a molar ratio of Al2O3:(10～20)SiO2:(10～20)Na2O:(240～360)H2And O, wherein the aging temperature is 20-60 ℃, and the aging time is 5-50 h.
8. The method according to claim 1, wherein the mass ratio of the cationic starch template to the alkali source to the water is (0.1-3): (0.2-2): (1-80), the hydrolysis is carried out at a temperature of 50-120 ℃.
9. The method of claim 1, wherein said reactive silica-alumina gel is present in a molar ratio of Al2O3:(4～15)SiO2:(1～5)Na2O:(150～280)H2And O, wherein the addition amount of the hydrolysate is 0.01-0.5 of the silicon source in the reactive silicon-aluminum gel.
10. The method according to claim 1, wherein the crystallization temperature of the gel mixture is 70 to 130 ℃ and the dynamic crystallization time is 10 to 50 hours.
11. The process of claim 1, wherein said dynamic crystallization is performed in a rotary oven.
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| US20150175432A1 (en) * | 2011-12-15 | 2015-06-25 | Petrochina Company Limited | Magnesium modified ultra-stable rare earth y-type molecular sieve and preparation method therefor |
| CN106927479A (en) * | 2015-12-30 | 2017-07-07 | 中国石油化工股份有限公司 | A kind of method for preparing mesoporous Y type molecular sieve |
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| US20150175432A1 (en) * | 2011-12-15 | 2015-06-25 | Petrochina Company Limited | Magnesium modified ultra-stable rare earth y-type molecular sieve and preparation method therefor |
| CN106927479A (en) * | 2015-12-30 | 2017-07-07 | 中国石油化工股份有限公司 | A kind of method for preparing mesoporous Y type molecular sieve |
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