阅读说明：本技术 一种NaY沸石及其制备方法 (NaY zeolite and preparation method thereof ) 是由 申宝剑 刘鹏 聂锁府 郭巧霞 于 2020-01-21 设计创作，主要内容包括：本发明提供一种NaY沸石及其制备方法。该NaY沸石制备方法包括：按照(4.6×10<Sup>-7</Sup>-2.0×10<Sup>-4</Sup>)聚丙烯酰胺:(10-30)Na<Sub>2</Sub>O:Al<Sub>2</Sub>O<Sub>3</Sub>:(10-30)SiO<Sub>2</Sub>:(150-450)H<Sub>2</Sub>O的摩尔比,将硅源、铝源、聚丙烯酰胺和水混合,制备得到导向剂；按照(1-4)Na<Sub>2</Sub>O:Al<Sub>2</Sub>O<Sub>3</Sub>:(7-10)SiO<Sub>2</Sub>:(100-300)H<Sub>2</Sub>O的摩尔比,将导向剂、硅源、碱源、铝源和水混合,制备得到反应混合物凝胶,以反应混合物凝胶的总质量为100％计,导向剂的用量占5％-15％；将制备得到的反应混合物凝胶进行晶化反应制备得到所述NaY沸石。该制备方法能够制备出高结晶度、片状、小晶粒的NaY沸石。(The invention provides NaY zeolite and a preparation method thereof, wherein the preparation method of the NaY zeolite comprises the following steps of (4.6 × 10) ‑7 ‑2.0×10 ‑4 ) Polyacrylamide (10-30) Na 2 O:Al 2 O 3 :(10‑30)SiO 2 :(150‑450)H 2 Mixing a silicon source, an aluminum source, polyacrylamide and water according to the molar ratio of O to prepare a guiding agent; according to (1-4) Na 2 O:Al 2 O 3 :(7‑10)SiO 2 :(100‑300)H 2 Mixing a guiding agent, a silicon source, an alkali source, an aluminum source and water according to the molar ratio of O to prepare reaction mixture gel, wherein the guiding agent accounts for 5-15% of the total mass of the reaction mixture gel as 100%; and carrying out crystallization reaction on the prepared reaction mixture gel to obtain the NaY zeolite. The preparation method can prepare high crystallinityFlaky and small-grained NaY zeolite.)

1. A method for preparing NaY zeolite, wherein the method comprises:

1) preparation of directing agent according to (4.6 × 10)^-7-2.0×10^-4) Polyacrylamide (10-30) Na₂O:Al₂O₃:(10-30)SiO₂:(150-450)H₂Mixing a silicon source, an aluminum source, polyacrylamide and water according to the molar ratio of O to prepare a guiding agent;

2) preparation of reaction mixture gel: according to (1-4) Na₂O:Al₂O₃:(7-10)SiO₂:(100-300)H₂Mixing a guiding agent, a silicon source, an alkali source, an aluminum source and water according to the molar ratio of O to prepare reaction mixture gel; wherein, the amount of the guiding agent accounts for 5 to 15 percent based on the total mass of the reaction mixture gel as 100 percent;

3) crystallization of reaction mixture gel: and 2) carrying out crystallization reaction on the reaction mixture gel prepared in the step 2) to prepare the NaY zeolite.

2. The production method according to claim 1,

the silicon source comprises at least one of water glass, silica sol, white carbon black and sodium silicate;

the aluminum source comprises at least one of sodium metaaluminate, high-alkali sodium metaaluminate, aluminum sulfate and aluminum nitrate;

the alkali source comprises at least one of sodium metaaluminate, high-alkali sodium metaaluminate, sodium hydroxide and potassium hydroxide.

3. The preparation method of claim 1, wherein the directing agent is prepared by mixing the silicon source, the aluminum source, the polyacrylamide and the water in the step 1) and then aging the mixture at 10 to 50 ℃ for 4 to 60 hours.

4. The method of claim 1, wherein the preparation of the reaction mixture gel is performed at 30-70 ℃.

5. The method of claim 1, wherein the step 2) of mixing the directing agent, the silicon source, the alkali source, the aluminum source, and the water comprises: firstly, mixing a guiding agent and a silicon source, and then adding an alkali source, an aluminum source and water to prepare reaction mixture gel;

preferably, the alkali source is added first and then the aluminum source.

6. The preparation method according to claim 1, wherein the temperature of the crystallization reaction in the step 3) is 70-100 ℃, and the time of the crystallization reaction is 6-50 h.

7. The preparation method of claim 1, wherein the flaky small-grained NaY zeolite is obtained by filtering, washing and drying after the crystallization reaction in the step 3).

8. A NaY zeolite obtained by the method for producing a NaY zeolite as claimed in any one of claims 1 to 7, which has a crystallinity of 90% or more and a silica-alumina molar ratio of SiO₂/Al₂O₃4.5-5.9, grain size of 300nm or less, and sodiumThe nanometer flake NaY zeolite has nanometer flake thickness of 50-100 nm.

9. The NaY zeolite of claim 8, wherein,

the specific surface area of the NaY zeolite is 700m²More than g, and the mesoporous volume is 0.101-0.150cm³Per g, pore volume 0.440cm³More than g;

the crystal grain size of the NaY zeolite is 75-300 nm.

10. The NaY zeolite of claim 8, wherein the amount of the nano-platelet NaY zeolite is 10-60% based on 100% of the number of crystal grains of the NaY zeolite.

Technical Field

The invention belongs to the field of inorganic materials and catalysts, and particularly relates to NaY zeolite and a preparation method thereof.

Background

The Y zeolite has developed three-dimensional pore passages, adjustable acidity, good thermal stability and good hydrothermal stability, and is widely applied to the petroleum refining industry. Degree of crystallinity, silicon to aluminum ratio (SiO)₂/Al₂O₃) And the grain size are the most important factors influencing the properties and functions of the Y-type zeolite. When applied to catalytic cracking, higher crystal retention means more active centers and higher catalytic performance; the ratio of the framework silicon to the aluminum is properly improved, so that the reduction of the density of acid centers is facilitated, the acid strength is improved, and bimolecular hydrogen transfer reactions in catalytic cracking can be reduced, so that the method has the advantages of good coke selectivity and improved octane number, and has higher thermal stability and hydrothermal stability; the smaller grain size enables the zeolite to expose more active sites, is more beneficial to the conversion of heavy oil macromolecules, is also more beneficial to the diffusion of product molecules, and reduces the secondary cracking of intermediate useful products and the generation of coke.

NaY zeolite is the largest molecular sieve catalytic material, and is used as the main raw material for producing ultrastable Y zeolite (USY molecular sieve), and its performance directly affects the performance of USY molecular sieve, and further affects the performance of catalyst. The improvement of the property of the NaY zeolite not only can improve the stability of the active component USY molecular sieve of the catalytic cracking catalyst in the production process and improve the operation flexibility of the production, but also can improve the crystallinity, the pore structure property and the like of the USY molecular sieve, and has important significance for improving the property of the catalyst and expanding the competitiveness of catalyst services.

At present, the method for industrially producing NaY molecular sieves mostly adopts a guide agent method similar to those proposed by Grace company in US3639099 and US3671191, and NaY molecular sieve products with the crystallinity of more than 83 percent and the silicon-aluminum of about 5.0 can be synthesized by the method within 28 hours, but the crystallinity of more than 90 percent is difficult. In addition, the conventional grain size Y-type zeolite with the grain size of more than 500nm is prepared by the prior art. However, with the heavy oil product, the macromolecular reactant is difficult to diffuse into the crystal and further difficult to contact with the active site, so that the conventional grain size Y-type zeolite cannot meet the requirement of high-efficiency heavy oil conversion, and therefore, the preparation of small-grain Y-type zeolite becomes a focus of attention.

The small-grain Y-type zeolite has the advantages of higher specific surface area, shorter diffusion path, more easily-contacted active sites and the like, is favored by researchers, and has the effect equivalent to that of mesoporous Y-type zeolite. CN105314651A discloses a method for synthesizing small-grain Y-type zeolite, which adopts hexamethylenetetramine as an additive and obtains the small-grain Y-type zeolite with the grain size of 400-600nm through fractional crystallization, but the crystallinity is lower. CN1113814C adopts organic dispersant glycerol, ethylene glycol or isopropanol to prepare the small-grain Y-type zeolite with the grain size of 300-600 nm. There are also some methods of preparing small-grained Y-type zeolite (CN101007639B) having a size of 300nm or less using inorganic additives (pseudo-boehmite, alpha-gibbsite and beta-gibbsite), but having low crystallinity and low specific surface area. Although the nano Y-type zeolite is successfully prepared by CN104843738A, CN106698460A and CN106672996A, expensive organic additives or fluorine-containing compounds are used, and the dosage is high, which is not beneficial to industrial application and environmental protection. As for the research results at present, no mature method for synthesizing the small-grain (100-. In addition, in the synthesis process of ZSM-5 zeolite, a single small-molecule organic template (3, 5-dimethyl-N-butyl pyridine iodide) is provided for inhibiting the growth of a B axis of a ZSM-5 molecular sieve, so that the method (CN106587100B) for preparing the flaky ZSM-5 zeolite is provided, and the diffusion capacity of product molecules in the B axis direction is greatly improved.

If the advantages of the small-grained zeolite and the flaky zeolite are combined and are introduced into the preparation of the Y-type zeolite, the method is a breakthrough research result. Therefore, the research and development of the effective small-grain Y-type zeolite which is suitable for industrial production and has the nano-sheet structure has important significance for the field of zeolite catalysis.

Disclosure of Invention

The invention aims to provide a preparation method of NaY zeolite. The preparation method can synthesize the NaY zeolite with high crystallinity, sheet shape and small crystal grain in a short time.

In order to achieve the above object, the present invention provides a method for preparing NaY zeolite, wherein the method comprises:

1) preparation of directing agent according to (4.6 × 10)^-7-2.0×10^-4) Polyacrylamide (10-30) Na₂O:Al₂O₃:(10-30)SiO₂:(150-450)H₂Mixing a silicon source, an aluminum source, polyacrylamide and water according to the molar ratio of O to prepare a guiding agent;

2) preparation of reaction mixture gel: according to (1-4) Na₂O:Al₂O₃:(7-10)SiO₂:(100-300)H₂Mixing a guiding agent, a silicon source, an alkali source, an aluminum source and water according to the molar ratio of O to prepare reaction mixture gel; wherein, the amount of the guiding agent accounts for 5 to 15 percent based on the total mass of the reaction mixture gel as 100 percent;

3) gel crystallization of the reaction mixture: and 2) carrying out crystallization reaction on the reaction mixture gel prepared in the step 2) to prepare the NaY zeolite.

In the above method for preparing NaY zeolite, preferably, the silicon source includes at least one of water glass, silica sol, white carbon black and sodium silicate; in a preferred embodiment, the silicon source is water glass.

In the above method for preparing NaY zeolite, preferably, the aluminum source comprises at least one of sodium metaaluminate, high alkali sodium metaaluminate, aluminum sulfate and aluminum nitrate; in a preferred embodiment, the aluminum source is selected from high alkali sodium metaaluminate.

In the above method for preparing NaY zeolite, preferably, the alkali source comprises at least one of sodium metaaluminate, high alkali sodium metaaluminate, sodium hydroxide and potassium hydroxide; in a preferred embodiment, the aluminum source is selected from high alkali sodium metaaluminate.

In the method for preparing NaY zeolite, the polyacrylamide may be at least one selected from the group consisting of nonionic, cationic, anionic and amphoteric.

In the preparation method of the NaY zeolite, preferably, the silicon source, the aluminum source, the polyacrylamide and the water are mixed in the step 1), and then aged for 4-60 hours at 10-50 ℃ to prepare the directing agent.

In a specific embodiment, the silicon source, the aluminum source and the water are mixed, then the polyacrylamide is added, the mixture is stirred and mixed uniformly at the temperature of 10-50 ℃, and then the mixture is aged for 4-60 hours at the temperature of 10-50 ℃ to prepare the guiding agent.

In the preparation method of the NaY zeolite, the preparation mode of the directing agent can adopt both dynamic and static states.

In the above method for preparing NaY zeolite, preferably, the preparation of the reaction mixture gel is performed at 30 to 70 ℃.

In the above method for preparing NaY zeolite, preferably, the step 2) of mixing the directing agent, the silicon source, the alkali source, the aluminum source and the water comprises: firstly, mixing a guiding agent and a silicon source, and then adding an alkali source, an aluminum source and water to prepare reaction mixture gel; more preferably, the alkali source is added first and then the aluminum source. The guiding agent is mixed with the silicon source before the alkali source and the aluminum source are added, so that the guiding agent is favorably dispersed in the silicon source, and the interaction of polyacrylamide with the silicon source and the aluminum source is promoted. And an aluminum source is added after the alkali source is added, so that the good dispersion of the guiding agent in the silicon source is facilitated, and the interaction of the polyacrylamide with the silicon source and the aluminum source is further promoted.

In the preparation method of the NaY zeolite, the guiding agent and the silicon source are mixed, and the method can be realized by adding the guiding agent into the silicon source or adding the silicon source into the guiding agent.

In a specific embodiment, the guiding agent and the silicon source are mixed and stirred for 1-90 h; then adding an alkali source, an aluminum source and water, and stirring for 1-24h to prepare reaction mixture gel.

In the above method for preparing NaY zeolite, preferably, the temperature of the crystallization reaction in step 3) is 70 to 100 ℃.

In the above method for preparing NaY zeolite, preferably, the time of the crystallization reaction in step 3) is 6 to 50 hours.

In the above method for preparing NaY zeolite, preferably, the flaky small-grained NaY zeolite is obtained by filtering, washing and drying after the crystallization reaction in step 3).

In the preparation method of the NaY zeolite, the crystallization mode can adopt dynamic crystallization or static crystallization.

The invention also provides NaY zeolite prepared by the preparation method of the NaY zeolite, wherein the crystallinity of the NaY zeolite is more than 90 percent, and the SiO zeolite has the mole ratio of silicon to aluminum₂/Al₂O₃4.5-5.9, crystal grain size below 300nm, and nano-flake NaY zeolite with nano-flake thickness of 50-100 nm.

Among the above NaY zeolites, it is preferable that the NaY zeolite has a specific surface area of 700m²More than g, and the mesoporous volume is 0.101-0.150cm³Per g, pore volume 0.440cm³More than g.

In the above NaY zeolite, preferably, the NaY zeolite has a crystal grain size of 75 to 300 nm.

In the NaY zeolite, the amount of the nano-flake NaY zeolite is preferably 10% to 60% based on 100% of the number of crystal grains of the NaY zeolite.

The preparation method of the NaY zeolite provided by the invention adopts a guiding agent added with polyacrylamide to prepare reactant gel, and the reactant gel is crystallized to obtain the NaY zeolite with high crystallinity, nano-flake shape and small crystal grains. Compared with the prior art, the technical scheme provided by the invention has the following advantages:

1. the preparation method of the NaY zeolite provided by the invention can synthesize the crystallinity of more than 90% (even more than 95%) and the silicon-aluminum molar ratio (SiO) in relatively short time (such as 6-50h) with relatively low alkalinity and relatively low feeding silicon-aluminum ratio₂/Al₂O₃) NaY zeolite of 4.5-5.9, and the NaY zeolite contains partial nano-sheet NaY zeolite.

2. The NaY zeolite prepared by the preparation method of the NaY zeolite provided by the invention is small-grained NaY zeolite with the grain size of below 300nm (usually 75-300nm) and in a nanometer scale, and contains part of nano flaky NaY zeolite (usually 10% -60% of nano flaky NaY zeolite).

3. Na provided by the inventionThe NaY zeolite prepared by the preparation method of the Y zeolite has a better pore structure and a larger specific surface area (generally reaching 700 m)²More than g), a relatively large pore volume (typically up to 0.440 cm)³More than g), larger mesoporous volume (usually reaching 0.101-0.150 cm)³/g)。

4. The preparation method of NaY zeolite provided by the invention can be used for the existing industrial NaY zeolite production device, does not need to add other equipment, has better industrialization prospect, and has very important significance for improving the performance of the catalytic cracking catalyst.

5. The preparation method of the NaY zeolite provided by the invention has the advantages of small material dosage, low cost, high utilization rate, capability of realizing rapid preparation and simple process.

6. According to the preparation method of the NaY zeolite, the organic additive (polyacrylamide) is less in material feeding in the preparation process and wide in available types (including nonionic type, anionic type, cationic type and amphoteric type), the guiding agent added with the polyacrylamide can be prepared at a relatively mild temperature within a relatively short time, the preparation method provided by the invention can realize the completion of crystallization within a relatively short time, and compared with the conventional preparation method of the NaY zeolite, the preparation method has the advantages of energy consumption reduction and good industrial prospect.

Drawings

Figure 1A is an XRD pattern of the NaY zeolite provided in example 1.

Figure 1B is an XRD pattern of the NaY zeolite provided in comparative example 1.

Figure 1C is an XRD pattern of the NaY zeolite provided in comparative example 2.

Figure 1D is an XRD pattern of the NaY zeolite provided in comparative example 3.

Figure 2A is an SEM image of the NaY zeolite provided in example 1.

Fig. 2B is an SEM image of the NaY zeolite provided in comparative example 1.

Fig. 2C is an SEM image of the NaY zeolite provided in comparative example 2.

Figure 2D is an SEM image of the NaY zeolite provided in comparative example 3.

FIG. 3 shows example 1 and comparative example1. Comparative example 3, N of NaY zeolite provided in comparative example 3₂Physical adsorption desorption curve.

Detailed Description

The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited to the practical scope of the present invention.

In the examples and comparative examples according to the invention, the relative crystallinity and the silica-alumina ratio of the NaY zeolite synthesized were determined using an X-ray diffractometer model BRUKER D8 ADVANCE (BRUKER, germany) under the following experimental conditions: CuKa radiation (0.1541nm), tube voltage 40kV, and tube current 40 mA. The relative crystallinity was determined according to SH/T0340-92 standard method (Association for chemical industry standards), published by the national standards Press, 2000. The silica-alumina ratio was determined according to the SH/T0339-92 standard method (edited in the chemical industry standards, published by the Chinese Standard Press, 2000), and the unit cell constant of NaY zeolite was calculated according to the formula (1) and then the ratio was determined according to the formula Breck-Flanigen: calculated as Si/Al (25.858- α)/(α -24.191).

Wherein, A is a unit cell constant,lambda is CuK α₁Wavelength of radiation

h²+k²+l²Is the X-ray diffraction miller index sum of squares.