阅读说明：本技术 一种高硅铝比y型分子筛及其制备方法和应用 (Y-type molecular sieve with high silica-alumina ratio and preparation method and application thereof ) 是由 高杭 杜艳泽 秦波 柳伟 董立廷 于 2019-10-28 设计创作，主要内容包括：本发明公开一种高硅铝比Y型分子筛及其制备方法和应用,所述方法包括如下步骤：(1)采用NH-4F溶液浸渍处理NaY分子筛；(2)采用氟硅酸铵对步骤(1)经NH-4F溶液浸渍处理后的NaY分子筛进行脱铝补硅处理,得到高硅铝比Y型分子筛。所述方法可明显改善Y型分子筛在改性过程中脱铝补硅不均匀、表面缺铝富硅现象严重等问题,得到了高硅铝比、高结晶度、二次孔多、大比表面积的Y型分子筛。(The invention discloses a Y-type molecular sieve with high silica-alumina ratio, a preparation method and application thereof, wherein the method comprises the following steps: (1) by NH 4 Dipping the NaY molecular sieve in the F solution; (2) NH treatment of step (1) by ammonium fluosilicate 4 And (4) carrying out dealuminization and silicon supplement treatment on the NaY molecular sieve subjected to the impregnation treatment by the solution F to obtain the Y-type molecular sieve with the high silica-alumina ratio. The method isThe method can obviously improve the problems of non-uniform dealuminization and silicon supplementation, serious aluminum-lacking and silicon-rich phenomena on the surface and the like of the Y-shaped molecular sieve in the modification process, and the Y-shaped molecular sieve with high silicon-aluminum ratio, high crystallinity, more secondary holes and large specific surface area is obtained.)

1. A preparation method of a Y-type molecular sieve with high silica-alumina ratio is characterized by comprising the following steps: the method comprises the following steps:

(1) by NH₄Dipping the NaY molecular sieve in the F solution;

(2) NH treatment of step (1) by ammonium fluosilicate₄And (4) carrying out dealuminization and silicon supplement treatment on the NaY molecular sieve subjected to the impregnation treatment by the solution F to obtain the Y-type molecular sieve with the high silica-alumina ratio.

2. The method of claim 1, wherein: preparing NH with a certain concentration in the step (1)₄Solution FTaking a certain amount of conventional NaY molecular sieve and putting into NH₄And stirring the solution F at a low temperature for a period of time, washing with deionized water, and filtering for later use.

3. The method of claim 1, wherein: NH prepared in step (1)₄The concentration of the F solution is 10-40 wt%, a certain amount of Y-type molecular sieve is weighed and poured into NH₄The solution F is stirred at 0-30 ℃ for 5-50 min at a solid-to-liquid ratio of 1g/5 ml-1 g/10 ml.

4. The method of claim 3, wherein: NH prepared in step (1)₄The concentration of the F solution is 15-30 wt%, and the solution is stirred for 10-35 min at the temperature of 4-25 ℃.

5. The method of claim 1, wherein: in step (2), NH is firstly added to step (1)₄Adding deionized water into the NaY molecular sieve after the dipping treatment of the F solution, uniformly stirring, then adding an ammonium fluosilicate solution at a certain temperature, and finally washing, filtering and drying to obtain the Y-type molecular sieve.

6. The method of claim 1, wherein: in step (2), NH is firstly added to step (1)₄Adding deionized water into the NaY molecular sieve subjected to the impregnation treatment by the solution F, uniformly stirring, and then adding an ammonium fluosilicate solution at the temperature of 80-95 ℃.

7. The method of claim 1, wherein: in the step (2), deionized water is added into the molecular sieve obtained in the step (1) according to the solid-to-liquid ratio of 1g/5 ml-1 g/10ml, the mixture is uniformly stirred, and the mixture is placed in a water bath kettle at the set temperature of 80 ℃ to 95 ℃.

8. The method of claim 1, wherein: and (3) preparing 200-300 ml of 0.10-0.80 mol/L ammonium fluosilicate solution in the step (2), and dropwise adding the ammonium fluosilicate solution into the molecular sieve solution, so that the ammonium fluosilicate solution is completely dropwise added into the molecular sieve solution after 1-6 hours.

9. The method of claim 8, wherein: and (3) preparing 0.10-0.60 mol/L ammonium fluosilicate solution in the step (2), and completely dripping the ammonium fluosilicate solution into the molecular sieve solution after 2-4 hours.

10. The method of claim 1, wherein: and (3) after the ammonium fluosilicate solution is completely dripped into the system in the step (2), continuing aging the system for 1-5 hours.

11. The method of claim 1, wherein: and (3) in the process of adding the ammonium fluosilicate solution in the step (2), controlling the pH of the system to be 3-7 by adding acid.

12. The method of claim 1, wherein: the drying conditions in the step (2) are as follows: drying at 100-120 ℃ for 12-24 hours.

13. The Y-type molecular sieve prepared by the process of any of claims 1 to 12 characterized by: the properties were as follows: the specific surface area is 500-1000 m²A pore volume of 0.30 to 0.50 ml/g, a relative crystallinity of 70 to 130%, a unit cell parameter of 2.425 to 2.445 nm, and SiO₂/Al₂O₃The ratio is 15 to 50.

14. The Y-type molecular sieve of claim 13, characterized in that: the properties were as follows: the specific surface area is 700-960 m²The pore volume is 0.34-0.45 ml/g.

15. A hydrocracking catalyst characterized by: containing the Y-type molecular sieve of claim 13.

Technical Field

The invention relates to a high-silica-alumina-ratio Y-type molecular sieve, a preparation method and application thereof, in particular to a high-silica-alumina-ratio Y-type molecular sieve, a preparation method thereof and application thereof in hydrocracking.

Background

As a main active component of the hydrocracking catalyst, Y-type zeolite has a typical faujasite crystal structure with a grain size of about 1 μm. The crystallinity, silicon-aluminum ratio, pore structure and acid distribution of the Y-type zeolite can directly influence the cracking activity, product selectivity, product distribution of cracking reaction and the like of the hydrocracking catalyst.

In the preparation process of the hydrocracking catalyst, the quality of distillate oil products can be obviously improved, the proportion of the Y-type zeolite in the catalyst is reduced, and the activity stability of the catalyst is improved by improving the framework silica-alumina ratio of the Y-type zeolite. The framework silica-alumina ratio of the Y-type zeolite is closely linked with the hydrothermal stability of the Y-type zeolite. Low silicon to aluminum ratio (SiO)₂/Al₂O₃ = 3-4.2) is poor in hydrothermal stability, and therefore, the zeolite is not applied to the field of petrochemicals. High silicon-aluminum ratio (SiO) obtained after modification₂/Al₂O₃ More than 4.3) Y-type zeolite has been widely used as a catalytic material in the catalytic cracking, hydrocracking and other processes of petroleum processing due to its good hydrothermal stability and acid resistance, and has irreplaceable effect.

At present, the high-silica-alumina ratio Y-type zeolite is mainly prepared by a direct synthesis method and a post-treatment modification method. The direct synthesis method has the advantages of simple preparation steps, no loss of the crystallinity of the zeolite, simple process flow and the like. However, the direct synthesis method needs to add crown ethers or quaternary ammonium salt substances with high price as template agents, and has the problems of long crystallization time, low product yield and the like, thereby greatly increasing the preparation cost.

The Y-type molecular sieve with high silicon-aluminum ratio obtained by the post-treatment modification method is mainly characterized in that framework silicon-aluminum removal is carried out by one or more treatment methods of conventional acid, alkali and hydrothermal treatment, and a large amount of secondary mesoporous structures are generated. From 1983, Skeels and Breck have been in a hot direction for the research of obtaining zeolite with high silica-alumina ratio by a post-treatment modification method after ammonium fluosilicate is adopted to treat Y zeolite and ZSM-5 molecular sieve and Al in a zeolite framework is isomorphously replaced by Si.

CN104828839 discloses a preparation method of a small-grain Y-type molecular sieve, which comprises treating a small-grain NaY molecular sieve with an alkali-containing solution to control Na₂Small crystal grain NH with O content less than or equal to 2.5 wt%₄NaY, and reacting the resulting NH₄The NaY molecular sieve is modified by dealuminizing and silicon supplementing by using an ammonium fluosilicate aqueous solution, and is further dealuminized by hydrothermal treatment to increase the silicon-aluminum ratio of the framework. However, the method has the disadvantages of complex modification process, long modification time and high cost, and the molecular sieve needs to undergo three processes of ammonium exchange, ammonium fluorosilicate modification and hydrothermal treatment, so that the product yield is low, and the method is not beneficial to industrial large-scale application.

CN102198950 discloses a method for directly synthesizing NaY molecular sieve with high silica-alumina ratio, and the synthesis process does not use any organic or inorganic template agent, but the hydrothermal stability of the synthesized NaY molecular sieve with high silica-alumina ratio is poor, which is not beneficial to the industrial application of the molecular sieve.

In volume 27, No. 5P 681-686 of Petroleum institute (Petroleum processing), Wang Yu et al examined the influence of ammonium fluorosilicate with different concentrations on the modification of ZSM-22 molecular sieve on the pore structure and acidity of the molecular sieve, and found that the modification process can selectively remove part of strong acid centers of the molecular sieve, thereby inhibiting further cracking of n-decane.

The pure ammonium fluosilicate modified Y zeolite is difficult to obtain high crystallinity, high stability and high SiO₂/Al₂O₃The framework silica-alumina ratio of the Y zeolite (14.5-50) can be greatly improved through framework migration and other processes in hydrothermal treatment, but the product yield is low and is greatly wasted due to multiple modification environments, and the modification process is long, so that the preparation steps are simplified, and the SiO is improved₂/Al₂O₃The modification process of the Y zeolite is a problem which needs to be solved urgently.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the Y-type molecular sieve with high silicon-aluminum ratio, and the preparation method and the application thereof, the method can obviously improve the problems of non-uniform dealumination and silicon supplement, serious surface aluminum and silicon deficiency and the like of the Y-type molecular sieve in the modification process, and the Y-type molecular sieve with high silicon-aluminum ratio, high crystallinity, more secondary pores and large specific surface area is obtained.

A preparation method of a Y-type molecular sieve with high silica-alumina ratio comprises the following steps:

(1) by NH₄Dipping the NaY molecular sieve in the F solution;

(2) NH treatment of step (1) by ammonium fluosilicate₄And (4) carrying out dealuminization and silicon supplement treatment on the NaY molecular sieve subjected to the impregnation treatment by the solution F to obtain the Y-type molecular sieve with the high silica-alumina ratio.

The method comprises the step (1) of preparing NH with a certain concentration₄F solution, taking a certain amount of conventional NaY molecular sieve and placing into NH₄And stirring the solution F at a low temperature for a period of time, washing with deionized water, and filtering for later use.

In the above method, NH prepared in step (1)₄The concentration of the F solution is 10-40 wt%, preferably 15-30 wt%. Weighing a certain amount of Y-shaped molecular sieve and pouring into NH₄And in the solution F, the solid-to-liquid ratio is 1g/5 ml-1 g/10 ml. Stirring at 0-40 ℃ for 5-50 min, preferably 4-25 ℃, preferably 10-35 min. NH (NH)₄F modification is kept at low temperature, and NH is slowed down by controlling temperature₄F, corroding the speed of the molecular sieve framework to control the process so as to maintain the framework stability of the molecular sieve.

In the method, step (2) is first to step (1) via NH₄Adding deionized water into the NaY molecular sieve after the dipping treatment of the F solution, uniformly stirring, then adding an ammonium fluosilicate solution at a certain temperature, and finally washing, filtering and drying to obtain the Y-type molecular sieve.

In the above method, step (2) is first performed by NH-passing to step (1)₄Adding deionized water into the NaY molecular sieve subjected to the impregnation treatment by the solution F, uniformly stirring, and adding an ammonium fluosilicate solution at 50-95 ℃, preferably 80-95 ℃. After the molecular sieve skeleton is modified in the step (1), the skeleton stability is lower,the violent dealuminizing and silicon supplementing process is not easy to be carried out at a low temperature, and the dealuminizing and silicon supplementing modification of ammonium fluosilicate is carried out at a temperature of 80-95 ℃ so as to keep the stability of the framework in the modification process.

In the method, deionized water is added into the molecular sieve obtained in the step (1) according to the solid-to-liquid ratio of 1g/5 ml-1 g/10ml in the step (2), the mixture is uniformly stirred and placed in a water bath kettle, and the temperature is set to be 50 ℃ to 95 ℃, preferably 80 ℃ to 95 ℃.

In the method, 200-300 ml of 0.10-0.80 mol/L ammonium fluorosilicate solution, preferably 0.10-0.60 mol/L ammonium fluorosilicate solution is prepared in the step (2), and is dropwise added into the molecular sieve solution, the dropping speed is controlled, so that the ammonium fluorosilicate solution is completely dropped into the molecular sieve solution for 1-6 hours, preferably 2-4 hours.

In the method, after the ammonium fluosilicate solution is completely dripped in the step (2), the system is aged for 1-5 hours, preferably 2-4 hours.

In the method, in the adding process of the ammonium fluosilicate solution in the step (2), the pH of the system is controlled to be 3-7 by adding acid, preferably 3-5, and the acid can be sulfuric acid and/or nitric acid. Research results show that the content of the monomorphic silicon can be maximized by controlling the proper pH value, and the silicon supplementing process is facilitated.

In the method of the invention, the drying conditions in the step (2) are as follows: drying at 100-120 ℃ for 12-24 hours.

The high-silica-alumina-ratio modified Y-type molecular sieve prepared by the method has the following properties: the specific surface area is 500-1000 m²(iv)/g, preferably 700 to 960 m²A pore volume of 0.30 to 0.50 ml/g, preferably 0.34 to 0.45 ml/g, a relative crystallinity of 70 to 130%, a cell parameter of 2.425 to 2.445 nm, SiO₂/Al₂O₃The ratio is 15 to 50.

The hydrocracking catalyst has the high silica-alumina ratio modified Y-type molecular sieve as the cracking component. The catalyst is suitable for the conversion and cracking process of the condensed ring macromolecules in the hydrocracking process.

Compared with the prior art, the method can obtain the Y-shaped molecular sieve with high silicon-aluminum ratio, high crystallinity, more secondary pores and large specific surface area, and can be used as an active component of hydrocracking.

Drawings

Figure 1 is an XRD pattern of the Y-type molecular sieve prepared in example 1.

Fig. 2 is an SEM image of the Y-type molecular sieve prepared in example 2.

Detailed Description

The following examples further illustrate the preparation of the present invention, but are not to be construed as limiting the process of the present invention. The NaY type molecular sieve added in the preparation process has the following properties: SiO of NaY type molecular sieve₂With Al₂O₃The molar ratio of (A) to (B) is 2 to 5, and the specific surface area is 600 to 720 m²A pore volume of 0.30 to 0.33 ml/g and a unit cell constant of 2.460 to 2.466 nm. In the following examples and comparative examples,% is by mass unless otherwise specified.

Example 1

Preparing NH with the concentration of 25wt%₄F solution, weighing a certain amount of Y-type molecular sieve and pouring into NH₄In the solution F, the solid-to-liquid ratio was 1g/10ml, and the solution was stirred at 25 ℃ for 18 min and then filtered for use, and the sample was designated as sample 1.

Deionized water was added to the solution at a solid-to-liquid ratio of 1g/10ml to stir sample 1 uniformly, and the mixture was placed in a water bath at a set temperature of 95 ℃. 200ml of 0.17mol/L ammonium fluosilicate solution is prepared and is dripped into the molecular sieve solution drop by drop, and the dripping speed is controlled to ensure that the ammonium fluosilicate solution is dripped into the molecular sieve solution completely after 2 hours. After the ammonium fluosilicate solution is completely dripped, the system is continuously aged for 2 hours, and the Y-shaped molecular sieve is obtained after washing, suction filtration and drying.

Example 2

NH with the concentration of 18wt% is prepared₄F solution, weighing a certain amount of Y-type molecular sieve and pouring into NH₄In the solution F, the solid-to-liquid ratio was 1g/10ml, and the solution was stirred at 15 ℃ for 25 min and then filtered for use, and the sample was designated as sample 2.

Deionized water was added to the solution at a solid-to-liquid ratio of 1g/10ml to stir sample 2 uniformly, and the mixture was placed in a water bath at 80 ℃. 300 ml of 0.35mol/L fluorine are preparedAnd dropwise adding the ammonium silicate solution into the molecular sieve solution, and controlling the dropping speed to ensure that the ammonium fluosilicate solution is completely dropped into the molecular sieve solution after 3 hours. Simultaneously dripping concentrated sulfuric acid (H)₂SO₄98 percent of mass) and 0.2ml of the modified molecular sieve, and the pH =4 is kept in an acid-base environment. After the ammonium fluosilicate solution is completely dripped, the system is continuously aged for 3 hours, and the Y-shaped molecular sieve is obtained after washing, suction filtration and drying.

Example 3

Preparing NH with the concentration of 15wt%₄F solution, weighing a certain amount of Y-type molecular sieve and pouring into NH₄In the solution F, the solid-to-liquid ratio was 1g/5ml, and the solution was stirred at 5 ℃ for 30 min and then filtered for use, and the sample was designated as sample 3.

Deionized water was added to the solution at a solid-to-liquid ratio of 1g/10ml to stir sample 3 uniformly, and the mixture was placed in a water bath at a set temperature of 90 ℃. 200ml of 0.37mol/L ammonium fluosilicate solution is prepared and is dripped into the molecular sieve solution drop by drop, and the dripping speed is controlled to ensure that the ammonium fluosilicate solution is dripped into the molecular sieve solution completely after 3 hours. After the ammonium fluosilicate solution is completely dripped, the system is continuously aged for 2 hours, and the Y-shaped molecular sieve is obtained after washing, suction filtration and drying.

Example 4

NH with the concentration of 30wt% is prepared₄F solution, weighing a certain amount of Y-type molecular sieve and pouring into NH₄In the solution F, the solid-to-liquid ratio was 1g/5ml, and the solution was stirred at 15 ℃ for 20min and then filtered for use, and the sample was designated as sample 4.

Deionized water was added to the solution at a solid-to-liquid ratio of 1g/10ml to stir sample 4 uniformly, and the mixture was placed in a water bath at a set temperature of 95 ℃. 200ml of 0.58mol/L ammonium fluosilicate solution is prepared and is dripped into the molecular sieve solution drop by drop, and the dripping speed is controlled to ensure that the ammonium fluosilicate solution is dripped into the molecular sieve solution completely after 4 hours. Simultaneously dropwise adding concentrated nitric acid (HNO)₃65 mass percent) of the modified molecular sieve, and keeping the pH =5 under the acid-base environment of the modified molecular sieve. After the ammonium fluosilicate solution is completely dripped, the system is continuously aged for 2 hours, and the Y-shaped molecular sieve is obtained after washing, suction filtration and drying.

Example 5

NH with the concentration of 10wt% is prepared₄F solution, weighing a certain amount of Y-type molecular sieve and pouring into NH₄In the solution F, the solid-to-liquid ratio was 1g/10ml, and the solution was stirred at 10 ℃ for 30 min and then filtered for use, and the sample was designated as sample 5.

Deionized water was added to the solution at a solid-to-liquid ratio of 1g/10ml to stir the sample 5 uniformly, and the mixture was placed in a water bath at 80 ℃. 200ml of 0.10mol/L ammonium fluosilicate solution is prepared and is dripped into the molecular sieve solution drop by drop, and the dripping speed is controlled to ensure that the ammonium fluosilicate solution is completely dripped into the molecular sieve solution after 1 hour. Simultaneously dripping concentrated sulfuric acid (H)₂SO₄98 percent of mass) and 0.4ml of the modified molecular sieve, and the pH =3 is kept in an acid-base environment. After the ammonium fluosilicate solution is completely dripped, the system is continuously aged for 2 hours, and the Y-shaped molecular sieve is obtained after washing, suction filtration and drying.

Example 6

Preparing NH with the concentration of 25wt%₄F solution, weighing a certain amount of Y-type molecular sieve and pouring into NH₄In the solution F, the solid-to-liquid ratio was 1g/10ml, and the solution was stirred at 25 ℃ for 18 min and then filtered for use, and the sample was designated as sample 1.

Deionized water was added to the solution at a solid-to-liquid ratio of 1g/10ml to stir sample 1 uniformly, and the mixture was placed in a water bath at a set temperature of 50 ℃. 200ml of 0.17mol/L ammonium fluosilicate solution is prepared and is dripped into the molecular sieve solution drop by drop, and the dripping speed is controlled to ensure that the ammonium fluosilicate solution is dripped into the molecular sieve solution completely after 2 hours. After the ammonium fluosilicate solution is completely dripped, the system is continuously aged for 2 hours, and the Y-shaped molecular sieve is obtained after washing, suction filtration and drying.

Example 7

Preparing NH with the concentration of 25wt%₄F solution, weighing a certain amount of Y-type molecular sieve and pouring into NH₄In the solution F, the solid-to-liquid ratio was 1g/10ml, and the solution was stirred at 40 ℃ for 18 min and then filtered for use, and the sample was designated as sample 1.

Deionized water was added to the solution at a solid-to-liquid ratio of 1g/10ml to stir sample 1 uniformly, and the mixture was placed in a water bath at a set temperature of 95 ℃. 200ml of 0.17mol/L ammonium fluosilicate solution is prepared and is dripped into the molecular sieve solution drop by drop, and the dripping speed is controlled to ensure that the ammonium fluosilicate solution is dripped into the molecular sieve solution completely after 2 hours. After the ammonium fluosilicate solution is completely dripped, the system is continuously aged for 2 hours, and the Y-shaped molecular sieve is obtained after washing, suction filtration and drying.

Comparative example 1

Preparing ammonium nitrate solution with the concentration of 25wt%, weighing a certain amount of Y-shaped molecular sieve, and pouring into NH₄In the solution F, the solid-to-liquid ratio was 1g/10ml, and the solution was stirred at 25 ℃ for 18 min and then filtered for use, and the sample was designated as sample 1.

Deionized water was added to the solution at a solid-to-liquid ratio of 1g/10ml to stir sample 1 uniformly, and the mixture was placed in a water bath at a set temperature of 95 ℃. 200ml of 0.17mol/L ammonium fluosilicate solution is prepared and is dripped into the molecular sieve solution drop by drop, and the dripping speed is controlled to ensure that the ammonium fluosilicate solution is dripped into the molecular sieve solution completely after 2 hours. After the ammonium fluosilicate solution is completely dripped, the system is continuously aged for 2 hours, and the Y-shaped molecular sieve is obtained after washing, suction filtration and drying.

Comparative example 2

The catalyst obtained by the preparation method of CN104828839 patent example 1.

Table 1 shows sample properties of examples and comparative examples.

The application of the modified Y-type molecular sieve in the flexible hydrocracking catalyst comprises the following steps:

the flexible hydrocracking catalyst preparation method comprises the following steps: uniformly mixing the modified Y-type molecular sieve, aluminum oxide, molybdenum oxide, tungsten oxide, nickel oxide and sesbania powder according to a certain proportion, uniformly rolling and molding the powder by taking an inorganic acid solution as an adhesive, drying for 24 hours, putting the powder into a muffle furnace, and roasting for 6 hours at the set temperature of 500 ℃ to obtain the hydrocracking catalyst, wherein the properties of the hydrocracking catalyst are shown in Table 2.

Catalyst evaluation conditions: the catalyst was presulfided and then placed in a 200ml small hydrogenation unit for evaluation. The properties of the raw oil used in the evaluation experiment are shown in Table 3, and the evaluation process conditions and the catalyst reaction performance comparison results are shown in Table 4. When the series of flexible hydrocracking catalysts are evaluated, raw oil sequentially passes through two beds of a hydrofining catalyst and a hydrocracking catalyst. Wherein, when passing through a hydrofining catalyst bed, the organic nitrogen content in the raw oil needs to be controlled to be less than 10 ppm.

TABLE 1 physicochemical Properties of modified Y-type molecular sieves

TABLE 2 composition of hydrocracking catalyst

TABLE 3 Properties of the raw materials

TABLE 4 Process conditions and catalyst reactivity

As shown in Table 4, when the reaction conversion rate is controlled to be the same, the reaction temperature of the catalyst in the example using the modified Y-type molecular sieve is obviously lower than that of the catalyst in the comparative example, and is 6-14 ℃. The yield of heavy naphtha (65-177 ℃) is improved by 2.2-15.0 percentage points, and the aromatic hydrocarbon is improved by 1-11 percentage points. The yield of the aviation kerosene (177-260 ℃) is improved by 1.0-6.9 percent. The result shows that the flexible hydrocracking catalyst prepared by the modified Y-type molecular sieve obtained by the method has better reaction activity and target product selectivity.