CN111086994B - Method for synthesizing mesoporous high-crystallinity Y-type molecular sieve - Google Patents
Method for synthesizing mesoporous high-crystallinity Y-type molecular sieve Download PDFInfo
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Abstract
A process for synthesizing a highly crystalline Y-type molecular sieve containing mesopores, characterized in that the process comprises: adding an alkali source and water into a 2, 3-epoxypropyltrimethylammonium chloride modified cationic starch template agent, and hydrolyzing at 30-150 ℃ to obtain a hydrolysate; the silicon source, the hydrolysate, the crystallization guiding agent, the aluminum source and the alkali are mixed in turn, and are kept stand and crystallized for 0.5 to 60 hours in a closed crystallization kettle at the temperature of between 60 and 180 ℃, and the product is recovered.
Description
Technical Field
The invention relates to a method for synthesizing 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 crude oil, the excellent properties of the high crystallinity Y-type molecular sieve containing mesopores are gradually revealed. The mesoporous-containing high-crystallinity Y-type molecular sieve has a micropore and mesopore 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 it does not meet the use requirement of FCC.
CN103214003A discloses a mesoporous Y-type molecular sieve, which is characterized in that amphiphilic organosilane N, N-dimethyl-N- [ 3- (trimethylsilyl) propyl ] octadecylammonium chloride (TPOAC) is used as a mesoporous template 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 finds out on the basis of a great amount of experiments that when a cationic starch template agent subjected to hydrolysis treatment is added in the synthesis process of the NaY molecular sieve, the feeding sequence is optimized, and the Y-type molecular sieve containing mesopores with higher crystallinity can be synthesized. Based on this, the present invention was made.
The invention aims to provide a short-flow and low-cost method for synthesizing a high-crystallinity mesopore-containing Y-type molecular sieve.
The invention provides a method for synthesizing a high-crystallinity Y-type molecular sieve containing mesopores, which is characterized by comprising the following steps:
(1) 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) adding an alkali source and water into a 2, 3-epoxypropyltrimethylammonium chloride modified cationic starch template with the substitution degree of 0.01-10%, wherein the mass ratio of the cationic starch template to the alkali source to the water is (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 and stirring a silicon source, the hydrolysate obtained in the step (2), the crystallization directing agent obtained in the step (1), an aluminum source and alkali in a feeding sequence to obtain an initial mixture, wherein the addition amount of the hydrolysate is 0.01-0.8 of the mole number of the silicon source in the initial mixture, and the silicon source in the initial mixture is calculated by a cationic starch template;
(4) and (4) violently stirring the initial mixture obtained in the step (3) for 0.5-10 hours to obtain a uniform gel mixture, standing and crystallizing the uniform gel mixture in a closed crystallization kettle at the temperature of 60-180 ℃ for 0.5-60 hours, and recovering the product.
According to the synthesis method provided by the invention, the used 2, 3-epoxypropyltrimethylammonium chloride modified cationic starch template agent is easy to obtain, the price is low, the price per ton is about 5000, the dosage is small, and the template agent is easy to separate from a bulk phase (based on filtering filtrate after synthesis); the invention also particularly adopts the charging sequence of water glass → (hydrolysis product of cationic starch template mixture) → directing agent → aluminum sulfate → sodium metaaluminate. The Y-type molecular sieve synthesized 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 a XRD spectrum of a high-crystallinity Y-type molecular sieve containing mesopores synthesized by the method of the present invention (example 2) and a conventional NaY (comparative example 2).
FIG. 2 is a graph showing the low temperature nitrogen physisorption-desorption curves of the highly crystalline mesoporous Y-type molecular sieve containing mesopores synthesized by the method of the present invention (example 2) and conventional NaY (comparative example 2).
Detailed Description
A method for synthesizing a Y-type molecular sieve with high crystallinity and medium pores is characterized in that the preparation method comprises the following steps:
(1) 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) adding an alkali source and water into a 2, 3-epoxypropyltrimethylammonium chloride modified cationic starch template with the substitution degree of 0.01-10%, wherein the mass ratio of the cationic starch template to the alkali source to the water is (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 and stirring a silicon source, the hydrolysate obtained in the step (2), the crystallization directing agent obtained in the step (1), an aluminum source and alkali in a feeding sequence to obtain an initial mixture, wherein the addition amount of the hydrolysate is 0.01-0.8 of the mole number of the silicon source in the initial mixture, and the silicon source in the initial mixture is calculated by a cationic starch template;
(4) and (4) violently stirring the initial mixture obtained in the step (3) for 0.5-10 hours to obtain a uniform gel mixture, standing and crystallizing the uniform gel mixture in a closed crystallization kettle at the temperature of 60-180 ℃ for 0.5-60 hours, 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, 2, 3-epoxypropyl trimethyl ammonium chloride modified cationic starch with different degrees of substitution is used as a template agent, and the generated template effect promotes the improvement of the crystallinity of the Y-type molecular sieve and simultaneously can form a certain mesopore, thereby playing a role in dual guidance. The template agent cationic starch provided by the invention is hydrolyzed into hydrophilic water-soluble gel, and has strong interaction with silicon dioxide or silicon aluminum 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.
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). The substitution degree refers to the amount of substances of which the active hydroxyl groups on each D-glucose unit of the starch are substituted, and is 0.01 to 10 percent, preferably 0.1 to 5 percent.
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.
Preferably, in the preparation of the crystallization guiding agent in the step (1), the molar ratio 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.
Preferably, the mass ratio of the cationic starch template agent, the alkali source and the water in the step (2) is (1-3): (1-6): (1-80), and hydrolyzing at 30-120 ℃.
Preferably, the initial mixture Al of step (3)2O3:(4～15)SiO2:(1～5)Na2O:(150～280)H2The molar ratio of O and the addition amount of the template agent are 0.01-0.5 of the mole number of the silicon source in the initial mixture.
Preferably, the crystallization temperature in the step (4) is 70-130 ℃, and the standing crystallization time is 10-50 h.
The procedures for recovering the product are well known to those skilled in the art, and are generally the steps of filtering, drying and calcining, and will not be described in detail herein.
The invention is further illustrated by the following examples and comparative examples, without restricting the content of the invention thereto.
In each example, the crystalline structure of the product was determined by X-ray diffraction (XRD) and a spectrum at an angle of 5 to 35 ° 2 θ 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 the temperature of 30 ℃ for 20 hours to obtain the crystallization directing agent.
1g of YZA-1 cationic starch (the substitution degree of 2, 3-epoxypropyltrimethylammonium chloride is 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 YZA-1 cationic starch (with the substitution degree of 1%) aqueous solution after the hydrolysis treatment into 50ml of water glass (with the modulus of 3.3), stirring for 0.5h, adding 12g of guiding agent, stirring for 1h, adding 30ml of aluminum sulfate and 10ml of sodium metaaluminate, continuing stirring for 1h after the addition is finished, finally placing the mixture into a stainless steel crystallization kettle, standing and crystallizing for 30h in a 90 ℃ oven after sealing, filtering, washing, drying a filter cake for 8h in a 120 ℃ oven, and roasting for 2h at 550 ℃ to obtain the Y-type molecular sieve.
The crystallinity and BET data are shown in table 1.
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 45 ℃ for 5 hours to obtain the crystallization directing agent.
2g of YZA-2 cationic starch (the substitution degree of 2, 3-epoxypropyltrimethylammonium chloride is 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 YZA-2 cationic starch (with the substitution degree of 0.5%) aqueous solution after the hydrolysis treatment into 65ml of water glass (with the modulus of 3.3), stirring for 0.5h, adding 18g of guiding agent, stirring for 1h, adding 40ml of aluminum sulfate and 18ml of sodium metaaluminate, continuing stirring for 1h after the addition is finished, finally placing the mixture into a stainless steel crystallization kettle, standing and crystallizing for 28h in a 95 ℃ oven after sealing, filtering, washing, drying a filter cake for 8h in a 120 ℃ oven, and roasting for 2h at 550 ℃ to obtain the Y-type molecular sieve.
The crystallinity and BET data are shown in table 1. The XRD spectrum is shown as the Meso-NaY curve in figure 1; the physical adsorption-desorption curve of the low-temperature desulfurization temperature nitrogen is shown in the Meso-NaY curve in fig. 2.
Comparative example 1
This comparative example illustrates comparative synthesis procedures and results with unhydrolyzed cationic starch added directly to the synthesis system.
The same as example 2 except that the cationic starch (degree of substitution 0.5%) as the template in comparative example YZA-2 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.
And adding 2g of YZA-2 cationic starch (the substitution degree of 2, 3-epoxypropyltrimethylammonium chloride is 0.5%) and 60g of water into 120ml of water glass (the modulus is 3.3), stirring for 1h, adding 24g of guiding agent 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, standing and crystallizing in a 95 ℃ oven for 28h after sealing, filtering, washing, drying a filter cake in the 120 ℃ oven for 8h, and roasting at 550 ℃ for 2h to obtain the mesoporous-containing Y-type molecular sieve with high crystallinity.
The crystallinity and BET data are shown in table 1.
Comparative example 2
This comparative example illustrates the synthesis process and results of a conventional NaY type molecular sieve.
The same as example 2 except that this comparative example was synthesized 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 18g of the directing agent into 65ml of water glass (modulus 3.3), stirring for 0.5h, adding 40ml of aluminum sulfate and 18ml of sodium metaaluminate, continuing stirring for 1h after the addition is finished, finally placing the mixture into a stainless steel crystallization kettle, sealing, standing and crystallizing in a 95 ℃ oven for 28h, filtering, washing, drying a filter cake in a 120 ℃ oven for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve.
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.
Comparative example 3
This comparative example illustrates the synthesis and results for different feed sequence mixing.
The same as example 2 except that the cationic starch (degree of substitution of 2, 3-epoxypropyltrimethylammonium chloride 0.5%) as templating agent of this comparative example YZA-2 was dosed in a different order.
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 YZA-2 cationic starch (the substitution degree of 2, 3-epoxypropyltrimethylammonium chloride is 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 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 placing the mixture into a stainless steel crystallization kettle, sealing, standing and crystallizing in a 95 ℃ oven for 28h, filtering, washing, drying a filter cake in a 120 ℃ oven for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve.
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 synthesis and results for different feed sequence mixing.
The same as example 2 except that the cationic starch (degree of substitution of 2, 3-epoxypropyltrimethylammonium chloride 0.5%) as templating agent of this comparative example YZA-2 was dosed in a different order.
According to Al2O3:15SiO2:16.5Na2O:320H2Molar ratio of O, 30ml of water glass (modulus 3.3) was added to 20.8ml of sodium hydroxideStirring and dissolving the sodium aluminate solution, and then aging for 20 hours at the aging temperature of 30 ℃ to obtain the crystallization directing agent.
Taking 2g of YZA-2 cationic starch, adding 1g of NaOH into 60g of water, uniformly stirring, heating to 60 ℃, and stirring at constant temperature for 1 hour for hydrolysis treatment.
Adding 18g of guiding agent into 65ml of water glass (modulus 3.3), stirring for 1h, adding 40ml of aluminum sulfate, stirring for 1h, adding YZA-2 cationic starch aqueous solution and 18ml of sodium metaaluminate after hydrolysis treatment, continuing stirring for 1h after the addition is finished, finally placing the mixture into a stainless steel crystallization kettle, sealing, standing and crystallizing in a 95 ℃ oven for 28h, filtering, washing, drying a filter cake in a 120 ℃ oven for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve.
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 5
This comparative example illustrates the synthesis and results for different feed sequence mixing.
The same as example 2 except that the cationic starch (degree of substitution of 2, 3-epoxypropyltrimethylammonium chloride 0.5%) as templating agent of this comparative example YZA-2 was dosed in a different order.
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 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 1h, adding 40ml of aluminum sulfate, stirring for 1h, adding YZA-2 cationic starch aqueous solution and 18ml of sodium metaaluminate after hydrolysis treatment, continuing stirring for 1h after the addition is finished, finally placing the mixture into a stainless steel crystallization kettle, sealing, standing and crystallizing in a 95 ℃ oven for 28h, filtering, washing, drying a filter cake in a 120 ℃ oven for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve.
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 6
This comparative example illustrates the synthesis and results for different feed sequence mixing.
The same as example 2 except that the cationic starch (degree of substitution of 2, 3-epoxypropyltrimethylammonium chloride 0.5%) as templating agent of this comparative example YZA-2 was dosed in a different order.
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.
Taking 2g of YZA-2 cationic starch, adding 1g of NaOH into 60g of water, uniformly stirring, heating to 60 ℃, and stirring at constant temperature for 1 hour for hydrolysis treatment.
Adding 40ml of aluminum sulfate into 65ml of water glass (modulus 3.3), stirring for 1h, adding YZA-2 cationic starch (substitution degree 0.5%) aqueous solution after hydrolysis treatment, stirring for 1h, adding 18g of directing agent and 18ml of sodium metaaluminate, continuing stirring for 1h after the addition, finally putting the mixture into a stainless steel crystallization kettle, standing and crystallizing for 28h in a 95 ℃ oven after sealing, filtering, washing, drying a filter cake for 8h in a 120 ℃ oven, and roasting for 2h at 550 ℃ to obtain the mesoporous Y-type molecular sieve with 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 7
This comparative example illustrates the synthesis and results for different feed sequence mixing.
The same as example 2 except that the cationic starch (degree of substitution of 2, 3-epoxypropyltrimethylammonium chloride 0.5%) as templating agent of this comparative example YZA-2 was dosed in a different order.
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 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 18ml of sodium metaaluminate into YZA-2 cationic starch aqueous solution after hydrolysis treatment, stirring for 1h, adding 65ml of water glass (modulus 3.3), stirring for 1h, adding 40ml of aluminum sulfate and 18g of directing agent, continuing stirring for 1h after the addition is finished, finally placing the mixture into a stainless steel crystallization kettle, sealing, standing and crystallizing in a 95 ℃ oven for 28h, filtering, washing, drying a filter cake in a 120 ℃ oven for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve.
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 substitution degree of 2, 3-epoxypropyltrimethylammonium chloride 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 YZA-3 cationic starch (with the substitution degree of 2%) aqueous solution after the hydrolysis treatment into 120ml of water glass (with the modulus of 3.3), stirring for 1h, adding 24g of guiding agent, stirring for 1h, adding 50ml of aluminum sulfate and 24ml of sodium metaaluminate, continuing stirring for 1h after the addition is finished, finally placing the mixture into a stainless steel crystallization kettle, sealing, standing in a 100 ℃ oven for crystallization for 24h, filtering, washing, drying a filter cake in the 120 ℃ oven for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve.
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: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.
8g of YZA-4 cationic starch (degree of substitution of 2, 3-epoxypropyltrimethylammonium chloride: 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.
Adding YZA-4 cationic starch aqueous solution after the hydrolysis treatment into 100g of water glass, stirring for 1h, then adding 20g of directing agent, stirring for 1h, then adding 45ml of aluminum sulfate and 20ml of sodium metaaluminate, continuing stirring for 1h after the addition is finished, finally placing the mixture into a stainless steel crystallization kettle, sealing, standing and crystallizing in a 110 ℃ oven for 20h, filtering, washing, drying the filter cake in a 120 ℃ oven for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve.
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 substitution degree of 2, 3-epoxypropyltrimethylammonium chloride is 0.8%) is put into 40g of water, 20ml of water glass is added, the mixture is stirred uniformly, the temperature is raised to 110 ℃, and the mixture is stirred at constant temperature for 0.5h for hydrolysis treatment.
And adding the YZC-2 cationic starch aqueous solution subjected to hydrolysis treatment into 80ml of water glass (modulus 3.3), stirring for 1h, adding 16g of directing agent, 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, standing and crystallizing for 18h in a 120 ℃ drying oven, filtering, washing, drying a filter cake for 8h in the 120 ℃ drying oven, and roasting for 2h at 550 ℃ to obtain the mesoporous-containing Y-type molecular sieve with 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 (the substitution degree of 2, 3-epoxypropyltrimethylammonium chloride is 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.
And adding the YZG-2 cationic starch aqueous solution subjected to hydrolysis treatment into 80ml of water glass (modulus 3.3), stirring for 1h, adding 16g of guiding agent, 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, standing and crystallizing in a 100 ℃ oven for 24h, filtering, washing, drying a filter cake in a 120 ℃ oven for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve.
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 8
This comparative example illustrates comparative synthesis procedures and results with unhydrolyzed cationic starch added directly to the synthesis system.
The same as example 6, except that the cationic starch templating agent of this comparative example YZG-2 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 45 ℃ for 5 hours to obtain the crystallization directing agent.
Adding 2g of YZG-2 cationic starch (the substitution degree of 2, 3-epoxypropyltrimethylammonium chloride is 5%) into 80ml of water glass (the modulus is 3.3) and 40g of water, stirring for 1h, adding 16g of guiding agent into a synthesis system, stirring for 1h, adding 36ml of aluminum sulfate and 18ml of sodium metaaluminate, continuing stirring for 1h after the addition is finished, finally placing the mixture into a stainless steel crystallization kettle, standing and crystallizing in a 100 ℃ oven for 24h after sealing, filtering, washing, drying a filter cake in a 120 ℃ oven for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve.
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 of 2, 3-epoxypropyltrimethylammonium chloride: 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 the YZG-4 cationic starch aqueous solution subjected to hydrolysis treatment into 100g of water glass, stirring for 1h, adding 20g of the guiding agent, stirring for 1h, adding 45ml of aluminum sulfate and 20ml of sodium metaaluminate, continuing stirring for 1h after the addition is finished, finally placing the mixture into a stainless steel crystallization kettle, sealing, standing and crystallizing in a 100 ℃ oven for 24h, filtering, washing, drying a filter cake in a 120 ℃ oven for 8h, and roasting at 550 ℃ for 2h to obtain the Y-type molecular sieve.
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 ofReferring to the mesopore volume of the molecular sieve obtained by the method of comparative example 2.
As can be seen from table 1, fig. 1 and fig. 2, the high-crystallinity Y-type molecular sieve containing mesopores prepared by the method of the present invention has a higher crystallinity and a more significant mesopore characteristic, the crystallinity and the mesopore characteristic in examples 1 to 7 are significantly higher than those in comparative examples 1 to 3, the sample in example 2 is more preferred than those in comparative examples 4 to 8, and the preferred addition sequence is water glass → (hydrolysate of mixed solution of cationic starch template agent) → directing agent → aluminum sulfate → sodium metaaluminate, so that the high-crystallinity Y-type molecular sieve containing mesopores can be synthesized, the high-crystallinity Y-type molecular sieve containing mesopores has a higher crystallinity and a higher mesopore characteristic, the template effect is exerted, the crystallinity of the Y-type molecular sieve is promoted to be improved, and a certain mesopore can be formed, and the dual directing effect is achieved.
Claims (10)
1. A process for synthesizing a highly crystalline Y-type molecular sieve containing mesopores, characterized in that the process comprises:
(1) 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) adding an alkali source and water into a 2, 3-epoxypropyltrimethylammonium chloride modified cationic starch template with the substitution degree of 0.01-10%, wherein the mass ratio of the cationic starch template to the alkali source to the water is (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 and stirring a silicon source, the hydrolysate obtained in the step (2), the crystallization directing agent obtained in the step (1), an aluminum source and alkali in a feeding sequence to obtain an initial mixture, wherein the addition amount of the hydrolysate is 0.01-0.8 of the mole number of the silicon source in the initial mixture, and the silicon source in the initial mixture is calculated by a cationic starch template;
(4) and (4) violently stirring the initial mixture obtained in the step (3) for 0.5-10 hours to obtain a uniform gel mixture, standing and crystallizing the uniform gel mixture in a closed crystallization kettle at the temperature of 60-180 ℃ for 0.5-60 hours, and recovering the product.
2. The method of claim 1, wherein the silicon source is one or more of ethyl silicate, water glass, sodium silicate and silica gel.
3. The process of claim 1 wherein the aluminum source is one or more 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 step (1) is as described aboveIn the preparation of the crystallization guiding agent, the molar ratio 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.
8. The method according to claim 1, wherein the mass ratio of the cationic starch template, the alkali source and the water in the step (2) is (0.1-3): (0.2-2): (1-80) and then heating and hydrolyzing at 30-120 ℃.
9. The method according to claim 1, wherein the initial mixture Al of step (3)2O3:(4～15)SiO2:(1～5)Na2O:(150～280)H2The molar ratio of O and the addition amount of the hydrolysate are 0.01-0.5 of the mole number of the silicon source in the initial mixture.
10. The method according to claim 1, wherein the crystallization temperature in the step (4) is 70-130 ℃, and the standing crystallization time is 10-50 h.
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