CN113149026A - Preparation method of molecular sieve with stepped pore structure - Google Patents
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Abstract
A preparation method of a gradient pore molecular sieve comprises the following steps: (1) dispersing a silicon source, an aluminum source and/or a phosphorus source and a template agent in water, stirring and mixing uniformly, placing the obtained mixture in a crystallization kettle, and heating in an oven for 0.5h-30d at the heating temperature of 5-300 ℃; (2) taking the sample obtained in the step (1) out of the oven, filtering and separating, fully washing with deionized water and drying; (3) roasting the dried sample obtained in the step (2) to remove the template agent in the molecular sieve, and simultaneously, ensuring that the crystallinity of the obtained initial molecular sieve is 50-90 percent and the completely crystallized sample is 100 percent; 4) and (4) carrying out hydrothermal treatment or chemical treatment on the sample obtained in the step (3) after the template agent is removed, and finally obtaining the gradient pore molecular sieve. The method realizes the regulation and control of the pore structure of the molecular sieve and simultaneously dissolves the compact and stable structure of the surface layer of the molecular sieve, thereby improving the mass transfer and diffusion capacity of the molecular sieve to a greater extent.
Description
Technical Field
The invention belongs to the technical field of molecular sieve synthesis, and relates to a synthesis and preparation method of a step pore molecular sieve.
Background
Molecular sieves are widely used in many fields such as adsorption, catalysis, separation and the like due to their large specific surface, unique pore structure and excellent adjustable acid properties. However, several kinds of molecular sieves widely used in industry, such as MFI, FAU, MOR, BEA, etc., are microporous materials, and their catalytic performance is limited due to their weak mass transfer and diffusion capacity caused by the narrow microporous orifice. Therefore, researchers take a series of measures to adjust the pore structure of the molecular sieve and improve the mass transfer diffusion capacity of the molecular sieve. The adopted means can be mainly divided into the following types, and the diffusion distance and the diffusion resistance are reduced by synthesizing the molecular sieve catalyst with the nanometer size; introducing intragranular mesopores into the molecular sieve, for example, adopting a template agent in the synthesis process, and removing the template agent by roasting after the crystallization synthesis stage is finished; and the pore structure of the molecular sieve is improved by adopting a chemical treatment method on the traditional microporous molecular sieve.
The outer layer structure of the molecular sieve is relatively stable and dense, which has a certain influence on the mass transfer diffusion (Journal of Physical Chemistry C,2013,117(48), 25545-25555). And during the subsequent chemical treatment process, the stable and dense shell is difficult to be dissolved and damaged, so that the chemical etching dissolves the internal structure of the molecular sieve crystal more (Chemistry of Materials,2019,31(13), 4639-. This phenomenon greatly restricts the improvement of the molecular sieve diffusion capacity by the post-treatment method.
Therefore, reasonable measures are taken to remove the compact outer shell of the outer layer of the molecular sieve particles or to convert the originally compact outer layer structure into a loose porous structure while introducing intragranular mesopores into the microporous molecular sieve, so that the mass transfer performance can be improved to a greater extent (Angewandte Chemie International Edition,48(2009), 533-538).
Disclosure of Invention
The surface structure of the molecular sieve is generally stable and is difficult to dissolve and damage in the post-treatment process. Compared with the internal structure of the molecular sieve, the surface structure of the molecular sieve is better retained after being treated by a conventional method, and the surface structure hinders the diffusion of molecules in the molecular sieve in the catalytic adsorption separation process and is not beneficial to improving the mass transfer capacity of the molecular sieve. Based on the understanding of the crystallization mechanism of the molecular sieve, the invention utilizes the general rule in the crystallization process, regulates the structural property of the initial molecular sieve by controlling the synthesis conditions, realizes the regulation of the surface layer property of the molecular sieve particles, and removes the compact structure of the surface layer of the molecular sieve while introducing step holes into the molecular sieve by post-treatment operation on the basis of the regulation, thereby obviously improving the adsorption and diffusion capacity of the molecular sieve. By controlling the synthesis conditions, the surface structure properties of the molecular sieve particles are regulated and controlled so that the molecular sieve particles are greatly dissolved in the post-treatment process, and the mass transfer capacity of the molecular sieve particles can be further improved.
The object of the present invention is to provide a method for the work-up of molecular sieves, in particular for the work-up modification of incompletely crystallized molecular sieves to a degree of crystallization which does not exceed 90% relative crystallinity, preferably 85% relative crystallinity and more preferably 80% relative crystallinity compared to the corresponding completely crystallized molecular sieves.
Under the limited conditions of the invention, the obtained molecular sieve sample which is not completely crystallized can have the crystal morphology which is unique to the topological structure molecular sieve and has a smooth and flat surface, but preferably the molecular sieve crystal has a rough surface and is still in a rapid crystallization stage, and the obtained crystallized product still has more amorphous species. The crystal morphology is observed by using a common scanning electron microscope method, and the invention has no special technical requirements. Wherein the mass ratio of the amorphous species in the final crystallized product (the solid-to-dry basis ratio after roasting at 550 ℃) is not less than 3%, preferably not less than 5%, more preferably not less than 8%.
The post-treatment method provided by the invention is characterized in that the formation of a compact layer on the surface of a molecular sieve crystal is jointly inhibited by simultaneously controlling the crystal growth of the molecular sieve and carrying out in-situ high-temperature alkali treatment. The dense layer is associated with two-dimensional growth at the later stage of molecular sieve crystallization. This stage of crystallization helps to form the characteristic crystal structure of the molecular sieve and reduces the formation of crystal defects such as twins and grain boundary tensions. On the other hand, the formation of the surface dense layer is not favorable for framework dealumination, desilication and secondary pore formation in the post-treatment modification process of the molecular sieve.
In order to achieve the purpose, the invention adopts the specific scheme that:
a preparation method of a gradient pore molecular sieve comprises the following steps:
(1) dispersing a silicon source, an aluminum source and/or a phosphorus source and a template agent in water, stirring and mixing uniformly, placing the obtained mixture in a crystallization kettle, and heating in an oven for 0.5h-30d at the heating temperature of 5-300 ℃;
(2) taking the sample obtained in the step (1) out of the oven, filtering and separating, fully washing with deionized water and drying;
(3) roasting the dried sample obtained in the step (2) to remove the template agent in the molecular sieve, and simultaneously, ensuring that the crystallinity of the obtained initial molecular sieve is 50-90 percent and the completely crystallized sample is 100 percent;
(4) and (4) carrying out hydrothermal treatment or chemical treatment on the sample obtained in the step (3) after the template agent is removed, and finally obtaining the gradient pore molecular sieve.
In the step (1), the silicon source is one or more of silica sol, silicon dioxide, water glass, white carbon black and tetraethyl orthosilicate; the aluminum source is one or more of aluminum nitrate, aluminum sulfate, aluminum isopropoxide, pseudo-boehmite, aluminum oxide and aluminum hydroxide; the phosphorus source is one or more of phosphoric acid, phosphate and organic phosphine compounds; the template agent is an organic structure directing agent or an inorganic structure directing agent, the organic structure directing agent is one or more of tetramethylammonium hydroxide, tetrapropylammonium hydroxide, ethylenediamine and hexamethylenediamine, and the inorganic directing agent is one or more of sodium hydroxide, potassium hydroxide and ammonia water.
In the step (1), the heating temperature is 30-250 ℃, and the heating time is 2 h-15 d.
And (2) a lining is arranged in the crystalloid reactor in the step (1), and the lining is made of polytetrafluoroethylene.
The molecular sieve prepared by the method can be a molecular sieve crystal with any topological structure, and the composition of the molecular sieve can be a pure silicon molecular sieve or a molecular sieve containing other heteroatoms such as aluminum or phosphorus; preferably, the molecular sieve crystals are MFI, FAU, MOR, BEA, LTA molecular sieves.
The crystallinity of the starting molecular sieve obtained in step (3) is 60% to 90%, more preferably the crystallinity is 65% to 85%, most preferably 70% to 80%, based on 100% of the completely crystallized sample; the relative crystallinity is measured by a conventional X-ray polycrystalline diffraction peak height method or a peak area method, and when the relative crystallinity is calculated, the completely crystallized same molecular sieve is selected as a reference sample, and the crystallinity is determined to be 100%. Preferably, the surface of the initial molecular sieve crystal is rough and still in the rapid crystallization stage, and the obtained crystallized product still has amorphous species.
In the step (4), the hydrothermal treatment temperature is 200-800 ℃, and the time is 0.5-24 h.
The chemical treatment in the step (4) comprises acid treatment or alkali treatment, wherein the concentration of the used chemical reagent is 0.01-40 wt%, the solid-liquid ratio is 1: 1-1: 40, the temperature is 20-100 ℃, and the treatment time is 5 min-72 h.
In a preferred technical scheme, before the crystallization of the molecular sieve in the step (1) is finished, the molecular sieve which is not completely crystallized is directly subjected to alkali treatment in situ; the alkali treatment is carried out at 20-120 ℃, preferably at the temperature which is not more than 10 ℃ different from the crystallization temperature of the molecular sieve, preferably not more than 5 ℃.
The invention has the beneficial technical effects that:
(1) the method has wide applicability, is suitable for the improvement of various molecular sieves, and has wide application prospect;
(2) the method regulates the structural property of the initial molecular sieve by controlling the synthesis condition, realizes the regulation of the surface layer property of the molecular sieve particles, and removes the compact structure of the surface layer of the molecular sieve while introducing step holes into the molecular sieve by post-treatment operation on the basis of the regulation, thereby obviously improving the adsorption and diffusion capacity of the molecular sieve.
(3) The method can be combined with various post-treatment methods, and the mass transfer capacity of the molecular sieve particles can be further improved by controlling the synthesis conditions and regulating and controlling the surface structure properties of the molecular sieve particles so that the molecular sieve particles are greatly dissolved in the post-treatment process.
Drawings
FIGS. 1.a and b are SEM images at 1 μm and 100nm of the MFI-1 sample of the feedstock molecular sieve in example 1, respectively;
FIGS. 2.a and b are SEM images at 1 μm and 100nm of a sample of the raw material molecular sieve MFI-R1 in comparative example 1, respectively;
FIG. 3 XRD patterns of the molecular sieves of the feedstock in example 1 and comparative example 1;
FIG. 4 is an SEM image of the molecular sieves prepared in example 1 and comparative example 1, wherein a and b are SEM images at 1 μm and 100nm of the sample of comparative example 1, respectively, and c and d are SEM images at 1 μm and 100nm of the sample of example 1;
FIG. 5 shows SEM spectra of molecular sieves of raw materials of example 3(a) and comparative examples 6(b) to 7(c), wherein the scales are both 100 nm;
FIG. 6 XRD patterns of example 3, comparative examples 6 and 7;
FIG. 7 SEM images of treated samples of example 3(a) and comparative example 6(b) with a scale of 100 nm.
Detailed Description
In order that the invention may be better understood, the following examples are included to further illustrate the invention and are not to be construed as limiting the invention.
Example 1
A preparation method of a gradient pore MFI molecular sieve comprises the following steps:
synthesizing a raw material MFI molecular sieve: dispersing 2.5g of sodium hydroxide and 20.3g of tetrapropylammonium hydroxide in 450g of deionized water, stirring for 1 hour at room temperature to fully dissolve the sodium hydroxide and the tetrapropylammonium hydroxide, and uniformly mixing; then 3.75g of aluminum nitrate nonahydrate and 52g of tetraethyl orthosilicate are added into the solution and stirred for 24 hours at room temperature; after the molecular sieve precursor is fully hydrolyzed and uniformly mixed, transferring the molecular sieve precursor into a crystallization kettle with a Teflon lining, putting the crystallization kettle into an oven, and heating for 10 hours at 170 ℃; then taking out the sample, filtering and separating the sample, fully washing the sample by using deionized water, and drying the sample at 100 ℃ for 12 hours to obtain a raw material MFI molecular sieve MFI-1, wherein the relative crystallinity of the raw material MFI molecular sieve MFI-1 is 76%;
preparing a step pore MFI molecular sieve: dispersing the MFI-1 molecular sieve obtained in the step 1) in 0.3mol/l sodium hydroxide solution at 65 ℃, wherein the solid-liquid mass ratio is 1:30, and continuously stirring for 0.5h at constant temperature. And after finishing, filtering the mixture, fully washing the obtained solid by using deionized water, and drying at 100 ℃ for 12 hours to obtain the gradient pore MFI molecular sieve.
Example 2
A preparation method of a gradient pore MFI molecular sieve comprises the following steps:
synthesizing a raw material MFI molecular sieve: dispersing 2.5g of sodium hydroxide in 150g of deionized water, stirring for 1 hour at room temperature to fully dissolve the sodium hydroxide and uniformly mixing; then 3.75g of aluminum nitrate nonahydrate and 52g of tetraethyl orthosilicate are added into the solution and stirred for 24 hours at room temperature; after the mixture is fully hydrolyzed and uniformly mixed, adding 50mgMFI molecular sieve crystal seeds, stirring for 30min to uniformly mix the mixture, transferring a molecular sieve precursor into a crystallization kettle with a Teflon lining, putting the crystallization kettle into an oven, and heating for 8h at 170 ℃; then taking out the sample, filtering and separating the sample, fully washing the sample by using deionized water, and drying the sample at 100 ℃ for 12 hours to obtain a raw material molecular sieve MFI-2 with the relative crystallinity of 78%;
preparing a step pore MFI molecular sieve: dispersing the MFI-2 molecular sieve obtained in the step 1) in 0.3mol/l sodium hydroxide solution at 65 ℃, wherein the solid-liquid mass ratio is 1:30, and continuously stirring for 30min at constant temperature. And after finishing, filtering the mixture, fully washing the obtained solid by using deionized water, and drying at 100 ℃ for 12 hours to obtain the gradient pore MFI molecular sieve.
Example 3
A preparation method of a stepped-hole ultrastable Y-type molecular sieve comprises the following steps:
synthesizing a raw material Y-type molecular sieve: 20.60g of sodium metaaluminate solution (21.0 wt% Na) was taken2O,3.20wt％ Al2O3) And 20.90g of water glass (28.45 wt% SiO)2,8.89wt％Na2O) uniformly dispersing the mixture in 8.60g of deionized water, stirring for 30min, standing and aging for 16h after the mixture is fully and uniformly mixed; 50g of the mixture, 75.86g of water glass and 16.88g of sodium metaaluminate are uniformly dispersed in 25g of deionized water, and 51.05g of aluminum sulfate solution (7.60 wt% Al) is added after stirring for 5 hours2O3) Continuously stirring for 1h, and then placing the obtained gel in a crystallization kettle with a Teflon lining and heating for 10h at the temperature of 98 ℃; then taking out the sample, filtering and separating out the sample, fully washing the sample by using deionized water, and drying the sample at 100 ℃ for 12 hours to obtain a raw material molecular sieve Y-1 with the relative crystallinity of 72%;
preparing a stepped-hole ultrastable Y molecular sieve: adding the 30gY molecular sieve obtained in the step 1) and 30g of ammonium chloride into 300 g of distilled water, stirring uniformly, and then stirring and exchanging for 1h at the temperature of 90 ℃. The pH of the exchange slurry was adjusted to 3.0 and maintained during the exchange using 1mol/L hydrochloric acid solution. After the exchange is finished, filtering and washing to obtain an ammonium exchange product; and (3) placing the molecular sieve subjected to ammonium ion exchange treatment in a hydrothermal furnace at 650 ℃, and roasting for 4 hours in an atmosphere of 100% water vapor to obtain the stepped-hole ultrastable Y molecular sieve.
Comparative example 1
Dispersing 2.5g of sodium hydroxide and 20.3g of tetrapropylammonium hydroxide in 450g of deionized water, stirring for 1 hour at room temperature to fully dissolve the sodium hydroxide and the tetrapropylammonium hydroxide, and uniformly mixing; then 3.75g of aluminum nitrate nonahydrate and 52g of tetraethyl orthosilicate are added into the solution and stirred for 24 hours at room temperature; after the molecular sieve precursor is fully hydrolyzed and uniformly mixed, transferring the molecular sieve precursor into a crystallization kettle with a Teflon lining, putting the crystallization kettle into an oven, and heating for 18h at 170 ℃; then taking out a sample, filtering and separating the sample, fully washing the sample by using deionized water, and drying the sample at 100 ℃ for 12 hours to obtain a raw material molecular sieve MFI-R1 with the relative crystallinity of 95%;
preparing a gradient pore MFI molecular sieve: dispersing the MFI-R1 molecular sieve obtained in the step 1) in 0.3mol/l sodium hydroxide solution at 65 ℃, wherein the solid-liquid mass ratio is 1:30, and continuously stirring for 30min at constant temperature. After the end, the mixture was filtered, the resulting solid was washed thoroughly with deionized water and dried at 100 ℃ for 12h to obtain the step-hole MFI molecular sieve described in comparative example 1.
Comparative example 2
Dispersing 2.5g of sodium hydroxide and 20.3g of tetrapropylammonium hydroxide in 450g of deionized water, stirring for 1 hour at room temperature to fully dissolve the sodium hydroxide and the tetrapropylammonium hydroxide, and uniformly mixing; then 3.75g of aluminum nitrate nonahydrate and 52g of tetraethyl orthosilicate are added into the solution and stirred for 24 hours at room temperature; after the molecular sieve precursor is fully hydrolyzed and uniformly mixed, transferring the molecular sieve precursor into a crystallization kettle with a Teflon lining, putting the crystallization kettle into an oven, and heating the crystallization kettle for 30 hours at 170 ℃; then taking out the sample, filtering and separating the sample, fully washing the sample by using deionized water, and drying the sample at 100 ℃ for 12 hours to obtain a raw material MFI molecular sieve MFI-R2, wherein the relative crystallinity of the raw material MFI molecular sieve MFI-R2 is 92%;
preparing a gradient pore MFI molecular sieve: dispersing the MFI-1 molecular sieve obtained in the step 1) in 0.3mol/l sodium hydroxide solution at 65 ℃, wherein the solid-liquid mass ratio is 1:30, and continuously stirring for 30min at constant temperature. After the end, the mixture was filtered, the resulting solid was washed thoroughly with deionized water and dried at 100 ℃ for 12h to obtain the step-hole MFI molecular sieve described in comparative example 2.
Comparative example 3
Dispersing 2.5g of sodium hydroxide and 20.3g of tetrapropylammonium hydroxide in 450g of deionized water, stirring for 1 hour at room temperature to fully dissolve the sodium hydroxide and the tetrapropylammonium hydroxide, and uniformly mixing; then 3.75g of aluminum nitrate nonahydrate and 52g of tetraethyl orthosilicate are added into the solution and stirred for 24 hours at room temperature; after the molecular sieve precursor is fully hydrolyzed and uniformly mixed, transferring the molecular sieve precursor into a crystallization kettle with a Teflon lining, putting the crystallization kettle into an oven, and heating the crystallization kettle at 180 ℃ for 10 hours; then taking out the sample, filtering and separating the sample, fully washing the sample by using deionized water, and drying the sample at 100 ℃ for 12 hours to obtain a raw material MFI molecular sieve MFI-R3, wherein the relative crystallinity of the raw material MFI molecular sieve MFI-R3 is 92%;
preparing a gradient pore MFI molecular sieve: dispersing the MFI-1 molecular sieve obtained in the step 1) in 0.3mol/l sodium hydroxide solution at 65 ℃, wherein the solid-liquid mass ratio is 1:30, and continuously stirring for 30min at constant temperature. After the end, the mixture was filtered, the resulting solid was washed thoroughly with deionized water and dried at 100 ℃ for 12h to obtain the step-hole MFI molecular sieve described in comparative example 3.
Comparative example 4
Dispersing 2.5g of sodium hydroxide and 20.3g of tetrapropylammonium hydroxide in 450g of deionized water, stirring for 1 hour at room temperature to fully dissolve the sodium hydroxide and the tetrapropylammonium hydroxide, and uniformly mixing; then 3.75g of aluminum nitrate nonahydrate and 52g of tetraethyl orthosilicate are added into the solution and stirred for 24 hours at room temperature; after the mixture is fully hydrolyzed and uniformly mixed, adding 50mg MFI molecular sieve seed crystal, stirring for 30min to uniformly mix the MFI molecular sieve seed crystal, transferring a molecular sieve precursor into a crystallization kettle with a Teflon lining, putting the crystallization kettle into an oven, and heating for 18h at 170 ℃; then taking out the sample, filtering and separating the sample, fully washing the sample by using deionized water, and drying the sample at 100 ℃ for 12 hours to obtain a raw material MFI molecular sieve MFI-R4, wherein the relative crystallinity of the raw material MFI molecular sieve MFI-R4 is 90%;
preparing a gradient pore MFI molecular sieve: dispersing the MFI-1 molecular sieve obtained in the step 1) in 0.3mol/l sodium hydroxide solution at 65 ℃, wherein the solid-liquid mass ratio is 1:30, and continuously stirring for 30min at constant temperature. After the end, the mixture was filtered, the resulting solid was washed thoroughly with deionized water and dried at 100 ℃ for 12h to obtain the step-hole MFI molecular sieve described in comparative example 4.
Comparative example 5
Dispersing 2.5g of sodium hydroxide and 20.3g of tetrapropylammonium hydroxide in 450g of deionized water, stirring for 1 hour at room temperature to fully dissolve the sodium hydroxide and the tetrapropylammonium hydroxide, and uniformly mixing; then 3.75g of aluminum nitrate nonahydrate and 52g of tetraethyl orthosilicate are added into the solution and stirred for 24 hours at room temperature; after the mixture is fully hydrolyzed and uniformly mixed, adding 50mg MFI molecular sieve seed crystal, stirring for 30min to uniformly mix the MFI molecular sieve seed crystal, transferring a molecular sieve precursor into a crystallization kettle with a Teflon lining, putting the crystallization kettle into an oven, and heating for 30h at 170 ℃; then taking out a sample, filtering and separating the sample, fully washing the sample by using deionized water, and drying the sample at 100 ℃ for 12 hours to obtain a raw material MFI molecular sieve MFI-R5, wherein the relative crystallinity of the raw material MFI molecular sieve MFI-R5 is 95%;
preparing a gradient pore MFI molecular sieve: dispersing the MFI-1 molecular sieve obtained in the step 1) in 0.3mol/l sodium hydroxide solution at 65 ℃, wherein the solid-liquid mass ratio is 1:30, and continuously stirring for 30min at constant temperature. After the end, the mixture was filtered, the resulting solid was washed thoroughly with deionized water and dried at 100 ℃ for 12h to obtain the step-hole MFI molecular sieve described in comparative example 5.
Comparative example 6
Synthesizing a raw material Y-type molecular sieve: 20.60g of sodium metaaluminate solution (21.0 wt% Na) was taken2O,3.20wt％ Al2O3) And 20.90g of water glass (28.45 wt% SiO)2,8.89wt％Na2O) uniformly dispersing the mixture in 8.60g of deionized water, stirring for 30min, standing and aging for 16h after the mixture is fully and uniformly mixed; 50g of the mixture, 75.86g of water glass and 16.88g of sodium metaaluminate are uniformly dispersed in 25g of deionized water, and 51.05g of aluminum sulfate solution (7.60 wt% Al) is added after stirring for 5 hours2O3) Continuously stirring for 1h, and then placing the obtained gel in a crystallization kettle with a Teflon lining and heating for 12h at the temperature of 98 ℃; then taking out the sample, filtering and separating the sample, fully washing the sample by using deionized water, and drying the sample at 100 ℃ for 12 hours to obtain a raw material Y-type molecular sieve Y-R1, wherein the relative crystallinity of the raw material Y-type molecular sieve Y-R1 is 93%;
preparing a stepped hole ultrastable Y molecular sieve: adding the molecular sieve 30g Y-R1 obtained in the step 1) and 30g of ammonium chloride into 300 g of distilled water, uniformly stirring, and then stirring and exchanging for 1h at the temperature of 90 ℃. The pH of the exchange slurry was adjusted to 3.0 and maintained during the exchange using 1mol/L hydrochloric acid solution. After the exchange is finished, filtering and washing to obtain an ammonium exchange product; and (3) placing the molecular sieve subjected to the ammonium ion exchange treatment in a hydrothermal furnace at 650 ℃, and roasting for 4 hours in a 100% water vapor atmosphere to obtain the stepped-hole ultrastable Y molecular sieve in the comparative example 6.
Comparative example 7
Synthesizing a raw material Y-type molecular sieve: 20.60g of sodium metaaluminate solution (21.0 wt% Na) was taken2O,3.20wt％ Al2O3) And 20.90g of water glass (28.45 wt% SiO)2,8.89wt％Na2O) it was uniformly dispersed in 8.60g of deionized water and stirred for 30minStanding and aging for 16h after the materials are fully and uniformly mixed; 50g of the mixture, 75.86g of water glass and 16.88g of sodium metaaluminate are uniformly dispersed in 25g of deionized water, and 51.05g of aluminum sulfate solution (7.60 wt% Al) is added after stirring for 5 hours2O3) Continuously stirring for 1h, and then placing the obtained gel in a crystallization kettle with a Teflon lining and heating for 18h at the temperature of 98 ℃; then taking out the sample, filtering and separating the sample, fully washing the sample by using deionized water, and drying the sample at 100 ℃ for 12 hours to obtain a raw material Y-type molecular sieve Y-R2, wherein the relative crystallinity of the raw material Y-type molecular sieve Y-R2 is 96%;
preparing a stepped hole ultrastable Y molecular sieve: adding the molecular sieve 30g Y-R2 obtained in the step 1) and 30g of ammonium chloride into 300 g of distilled water, uniformly stirring, and then stirring and exchanging for 1h at the temperature of 90 ℃. The pH of the exchange slurry was adjusted to 3.0 and maintained during the exchange using 1mol/L hydrochloric acid solution. After the exchange is finished, filtering and washing to obtain an ammonium exchange product; and (3) placing the molecular sieve subjected to the ammonium ion exchange treatment in a hydrothermal furnace at 650 ℃, and roasting for 4 hours in a 100% water vapor atmosphere to obtain the stepped-hole ultrastable Y molecular sieve in the comparative example 7.
The samples obtained in examples 1 to 3 and comparative examples 1 to 7 were characterized and the characterization parameters of the obtained samples are shown in Table 1.
TABLE 1 summary of structural parameters for examples and comparative examples
XRD analysis is carried out on the samples involved in the examples by using a Bruker D8 ADVANCE X-ray powder diffractometer, and the relative crystallinity of each sample is calculated by taking the crystallinity of a completely crystallized sample as 100%; the pore structure adopts Quadrasorb-evoTMAnalytical characterization was carried out, the specific surface being calculated by the BET method and the total pore volume being calculated as the sample at the relative pressure P/P0The adsorption amount at 0.99 is calculated, and the pore volume of the micropores is calculated by a t-plot method; SEM pictures the surface topography of the example and comparative samples was obtained by using Japanese Electron (JEOL) 7900F.
As shown in table 1, the catalyst prepared by the method of the present invention has a rough and porous surface, and the catalyst obtained by post-treating the completely crystallized raw material molecular sieve has a smooth surface, which indicates that the method of the present invention has a significant inhibiting effect on the formation of a dense layer on the surface of the molecular sieve crystal of the catalyst; more importantly, the increase of the mesoporous volume of the molecular sieve catalyst prepared by the method (the final mesoporous volume of the molecular sieve catalyst minus the mesoporous volume of the raw material molecular sieve) is obviously greater than the increase of the mesoporous volume of the completely crystallized or post-treated raw material molecular sieve with higher crystallization degree.
The foregoing is merely exemplary and illustrative of the principles of the present invention and various modifications, additions and substitutions of the specific embodiments described herein may be made by those skilled in the art without departing from the principles of the present invention or exceeding the scope of the claims set forth herein.
Claims (10)
1.A preparation method of a gradient pore molecular sieve comprises the following steps:
(1) dispersing a silicon source, an aluminum source and/or a phosphorus source and a template agent in water, stirring and mixing uniformly, placing the obtained mixture in a crystallization kettle, and heating in an oven for 0.5h-30d at the heating temperature of 5-300 ℃;
(2) taking the sample obtained in the step (1) out of the oven, filtering and separating, fully washing with deionized water and drying;
(3) roasting the dried sample obtained in the step (2) to remove the template agent in the molecular sieve, and simultaneously, ensuring that the crystallinity of the obtained initial molecular sieve is 50-90 percent and the completely crystallized sample is 100 percent;
(4) and (4) carrying out hydrothermal treatment or chemical treatment on the sample obtained in the step (3) after the template agent is removed, and finally obtaining the gradient pore molecular sieve.
2. The method according to claim 1, wherein the silicon source in step (1) is one or more of silica sol, silica, water glass, silica white and tetraethyl orthosilicate; the aluminum source is one or more of aluminum nitrate, aluminum sulfate, aluminum isopropoxide, pseudo-boehmite, aluminum oxide and aluminum hydroxide; the phosphorus source is one or more of phosphoric acid, phosphate and organic phosphine compounds; the template agent is an organic structure directing agent or an inorganic structure directing agent, the organic structure directing agent is one or more of tetramethylammonium hydroxide, tetrapropylammonium hydroxide, ethylenediamine and hexamethylenediamine, and the inorganic directing agent is one or more of sodium hydroxide, potassium hydroxide and ammonia water.
3. The method according to claim 1, wherein the heating temperature in step (1) is 30 to 250 ℃ and the heating time is 2h to 15 d.
4. The method according to claim 1, wherein the crystalloid reactor in step (1) is lined with polytetrafluoroethylene.
5. The method of claim 1, wherein the molecular sieve prepared by the method can be a molecular sieve crystal with any topological structure, and the composition of the molecular sieve crystal can be a pure silicon molecular sieve or a molecular sieve containing other heteroatoms such as aluminum or phosphorus; preferably, the molecular sieve crystals are MFI, FAU, MOR, BEA, LTA molecular sieves.
6. The process of claim 1, wherein the starting molecular sieve obtained in step (3) has a crystallinity of from 60% to 90%, more preferably from 65% to 85%, most preferably from 70% to 80%, based on 100% of the fully crystallized sample; the relative crystallinity is measured by a conventional X-ray polycrystalline diffraction peak height method or a peak area method, and when the relative crystallinity is calculated, the completely crystallized same molecular sieve is selected as a reference sample, and the crystallinity is determined to be 100%.
7. The method according to claim 1, wherein the hydrothermal treatment in the step (4) is carried out at a temperature of 200 to 800 ℃ for 0.5 to 24 hours.
8. The method according to claim 1, wherein the chemical treatment in the step (4) comprises acid treatment or alkali treatment, and the chemical agent is used at a concentration of 0.01 to 40 wt%, a solid-to-liquid ratio of 1:1 to 1:40, a temperature of 20 to 100 ℃, and a treatment time of 5min to 72 h.
9. The method according to claim 1, wherein before the crystallization of the molecular sieve in step (1) is completed, the molecular sieve which is not completely crystallized is subjected to an alkali treatment in situ; the alkali treatment is carried out at 20-120 ℃, preferably at the temperature which is not more than 10 ℃ different from the crystallization temperature of the molecular sieve, preferably not more than 5 ℃.
10. The process of claim 1, wherein the starting molecular sieve crystals are rough in surface and still in the rapid crystallization stage, and the resulting crystallized product still contains amorphous species.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114538468A (en) * | 2022-03-30 | 2022-05-27 | 南京大学 | Novel phosphorus-silicon molecular sieve material named NPS-1 and preparation method thereof |
| CN114890437A (en) * | 2022-06-22 | 2022-08-12 | 中国石油大学(华东) | Small-particle-size SAPO-34 molecular sieve quickly synthesized by MTO waste catalyst and preparation method thereof |
| CN115367769A (en) * | 2022-07-18 | 2022-11-22 | 常州工学院 | Preparation method and application of high-crystallinity hierarchical pore SAPO-56 zeolite molecular sieve |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101722022A (en) * | 2008-10-10 | 2010-06-09 | 中国石油天然气集团公司 | Alkali treatment modifying method of Y-shaped molecular sieve |
| CN103787356A (en) * | 2014-01-24 | 2014-05-14 | 东南大学 | Preparation method for hierarchical pore P-type molecular sieve |
| CN103979569A (en) * | 2014-06-04 | 2014-08-13 | 陕西省煤化工工程技术研究中心 | Preparation method of silicoaluminophosphate molecular sieve with hierarchical pore structure |
| CN104843731A (en) * | 2015-05-06 | 2015-08-19 | 河北工业大学 | Preparation method of nanometer stepped hole mordenite molecular sieve |
| WO2016090612A1 (en) * | 2014-12-11 | 2016-06-16 | 中国科学院大连化学物理研究所 | Synthesis method for mesoporous and microporous sapo-34 molecular sieve |
| CN106745055A (en) * | 2016-12-28 | 2017-05-31 | 河南大学 | A kind of synthetic method of the molecular sieves of monoblock type multi-stage porous ZSM 5 |
| CN107555446A (en) * | 2017-05-26 | 2018-01-09 | 中海油天津化工研究设计院有限公司 | A kind of preparation method of multi-stage porous Y type molecular sieve |
| CN107777700A (en) * | 2017-10-16 | 2018-03-09 | 中国石油天然气股份有限公司 | A kind of molecular sieves of step hole HZSM 5 and preparation method thereof |
-
2020
- 2020-09-28 CN CN202011036577.XA patent/CN113149026B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101722022A (en) * | 2008-10-10 | 2010-06-09 | 中国石油天然气集团公司 | Alkali treatment modifying method of Y-shaped molecular sieve |
| CN103787356A (en) * | 2014-01-24 | 2014-05-14 | 东南大学 | Preparation method for hierarchical pore P-type molecular sieve |
| CN103979569A (en) * | 2014-06-04 | 2014-08-13 | 陕西省煤化工工程技术研究中心 | Preparation method of silicoaluminophosphate molecular sieve with hierarchical pore structure |
| WO2016090612A1 (en) * | 2014-12-11 | 2016-06-16 | 中国科学院大连化学物理研究所 | Synthesis method for mesoporous and microporous sapo-34 molecular sieve |
| CN104843731A (en) * | 2015-05-06 | 2015-08-19 | 河北工业大学 | Preparation method of nanometer stepped hole mordenite molecular sieve |
| CN106745055A (en) * | 2016-12-28 | 2017-05-31 | 河南大学 | A kind of synthetic method of the molecular sieves of monoblock type multi-stage porous ZSM 5 |
| CN107555446A (en) * | 2017-05-26 | 2018-01-09 | 中海油天津化工研究设计院有限公司 | A kind of preparation method of multi-stage porous Y type molecular sieve |
| CN107777700A (en) * | 2017-10-16 | 2018-03-09 | 中国石油天然气股份有限公司 | A kind of molecular sieves of step hole HZSM 5 and preparation method thereof |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114538468A (en) * | 2022-03-30 | 2022-05-27 | 南京大学 | Novel phosphorus-silicon molecular sieve material named NPS-1 and preparation method thereof |
| CN114890437A (en) * | 2022-06-22 | 2022-08-12 | 中国石油大学(华东) | Small-particle-size SAPO-34 molecular sieve quickly synthesized by MTO waste catalyst and preparation method thereof |
| CN114890437B (en) * | 2022-06-22 | 2023-08-25 | 中国石油大学(华东) | Small-granularity SAPO-34 molecular sieve rapidly synthesized by MTO spent catalyst and preparation method thereof |
| CN115367769A (en) * | 2022-07-18 | 2022-11-22 | 常州工学院 | Preparation method and application of high-crystallinity hierarchical pore SAPO-56 zeolite molecular sieve |
| CN115367769B (en) * | 2022-07-18 | 2023-07-04 | 常州工学院 | Preparation method and application of high-crystallinity hierarchical pore SAPO-56 zeolite molecular sieve |
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