CN1029202C - Preparation method of ultrastable Y-type zeolite containing amorphous alumina - Google Patents

Abstract

The present invention relates to a method for preparing ultrastable Y-type zeolite containing amorphous aluminum oxide. In the method, aluminum gel is introduced into NaY or HNaY zeolite, and then ammonium ion exchange, filtration and hydrothermal calcination in a conventional hydrothermal method are performed to obtain USY zeolite containing 5-30 weight percent of amorphous _Al2O3 . Since the introduced aluminum gel can react with ammonium sulfate remaining in _the zeolite filtration, the destructive effect of the ammonium sulfate on the zeolite structure is reduced, and the amplitude of the fluctuation of the zeolite crystal retention caused by the fluctuation of the ammonium sulfate content is reduced. Therefore, the zeolite prepared by the present invention has a higher crystal retention than the zeolite prepared by the conventional hydrothermal method.

Description

The present invention relates to a method for preparing ultrastable Y-type zeolite containing amorphous alumina.

In the process of catalytic cracking of hydrocarbons, an important way to reduce the coke yield and increase the octane number of gasoline is to use ultra stable Y zeolite (USY) instead of conventional rare earth Y zeolite (REY) as the active component of the catalyst.

There are many preparation methods of USY zeolite. For example, it is reported in USP4273753 that Sicl ₄ steam is reacted with NaY zeolite at high temperature to prepare USY _zeolite . ) ₂ SiF ₆ solution treatment. However, based on the considerations of easy processing of production equipment, large production scale, and no environmental pollution, the current industry mainly uses the hydrothermal method based on USP3292192 to prepare USY zeolite. The main steps of the hydrothermal method are: NaY zeolite Ion exchange reaction with solution containing ammonium ions, filtration, and hydrothermal roasting process.

From the perspective of production cost, ammonium sulfate is usually used as the source of ion exchange ammonium ions. Due to the difference in the concentration of ammonium ions in the ion exchange step and the difference in the selection of filter equipment in the filtration step, the filter obtained after filtration is more or less banded. There is a part of free ammonium sulfate, which will react with the aluminum in the zeolite framework during the hydrothermal roasting process, accelerate the dealumination rate, cause the transitional collapse of the zeolite structure, and reduce the crystallization retention of USY zeolite. Though the method of reducing ammonium ion concentration in the exchange liquid or repeatedly washing and filtering can be adopted to reduce the content of free ammonium sulfate in the filter, reducing the ammonium ion concentration in the exchange liquid will reduce the production capacity of preparing USY zeolite, and repeatedly The washing method, because the salt in the filter is washed away, the filtration rate is greatly reduced, so that it is difficult to maintain normal production.

In order to solve the problems in the prior art, the object of the present invention is to provide a method for preparing USY zeolite with simple production process and high product crystal retention.

The preparation method of USY zeolite provided by the invention is:

1. Take an aluminum sulfate solution with a concentration of 3 to 6% by weight (calculated as Al ₂ O ₃ ), adjust its pH to 3.5 to 7.5 with ammonia water, preferably 3.5 to 5.5, and add NaY or HNaY zeolite to make the zeolite in the slurry : colloidal Al ₂ O ₃ =95-70:5-30, preferably 95-85:5-15 (weight ratio on a dry basis), and mix evenly.

2. The 1st step gain is mixed with ammonium sulfate and water by the conventional method of ammonium ion exchange in the USY zeolite process by hydrothermal method, and carries out ammonium ion exchange reaction, and wherein zeolite: ammonium sulfate: water is preferably 1: 0.8～ 1.5:10~40 (weight ratio).

3. Use ammonia water to adjust the pH value of the product obtained in step 2 to 6.5-8.5, preferably 6.5-7.5, and filter.

4. Filter the obtained product in step 3 and perform hydrothermal calcination according to the conventional method of hydrothermal calcination in the process of hydrothermal preparation of USY zeolite to obtain USY zeolite containing 5-30% by weight of amorphous Al ₂ O ₃ .

The above-mentioned HNaY zeolite can be the HNaY zeolite obtained after one ammonium ion exchange and one hydrothermal roasting of NaY zeolite prepared by the conventional hydrothermal method of USY zeolite.

In the method provided by the invention, colloidal alumina is introduced into the zeolite filter, and during hydrothermal calcination, the aluminum colloid will be mixed with the residue remaining in the filter Free ammonium sulfate interacts to reduce the damage of ammonium sulfate to the zeolite framework structure, and alleviate the crystallinity fluctuation of USY zeolite products caused by the fluctuation of free ammonium sulfate content in the filter, which is beneficial to obtain high-quality USY zeolite. Under the premise of stabilizing the production of USY zeolite. Compared with the USY zeolite produced by the conventional hydrothermal method, the USY zeolite prepared by the present invention has a higher degree of crystallization retention, which improves the catalytic activity of the catalyst containing the zeolite. In addition, the method provided by the present invention is simple and easy to implement, and is more applicable Preparation of USY zeolite on industrial scale.

The present invention will be further described below by embodiment.

Example 1~4

One. prepare zeolite by the method of the present invention

(1) Take 200 grams of aluminum sulfate (chemically pure, Beijing Chemical Plant) solution containing 5.0% by weight of Al ₂ O ₃ , adjust the pH value to 5.2 with 10% by weight of ammonia water, and add 90 grams of NaY zeolite (silicon aluminum Ratio 4.9, crystallinity 92%, Changling Catalyst Factory), mix well.

(2) Add appropriate amount of ammonium sulfate solution and water to the result of step (1) to make the content of zeolite, ammonium sulfate and water in the slurry reach the following ratio: (see the text for Table A)

Stir evenly, heat up to 90°C, carry out ion exchange reaction under stirring for 1.0 hour,

(3) Use ammonia water to adjust the pH value of the product obtained in step (2) to 6.5, and filter.

(4) The filter obtained in step (3) (solid content 41.7% by weight) is put into a stainless steel tubular reactor, heated to 570°C, and roasted in 100% water vapor for 2.0 hours to obtain 10% by weight amorphous oxide Aluminum zeolites A, B, C and D.

2. Preparation of comparative zeolite samples by conventional hydrothermal method

(1) Take 100 grams of NaY respectively to carry out ammonium ion exchange reaction according to the method in step (2) of the first part, and filter.

(2) The product obtained in step (1) is subjected to hydrothermal calcination according to the method in step (4) of the first part, and the comparative zeolite samples A-comparative, B-comparative, C-comparative and D-comparative are obtained.

3. Determination of structural parameters of zeolite

The crystallization retention of unit cell constants of zeolites A~D and comparison zeolite samples A-comparison~D-comparison were measured by X-ray diffraction method, and the sodium content, aluminum content and ^SO2- content in zeolite were determined by conventional chemical methods , the results are shown in Table 1.

As can be seen from Table 1, with the reduction of water in the ion exchange step, the SO ^2- ₄ in the filter

content increases, the comparison zeolite produced by the conventional hydrothermal method increases its unit cell shrinkage while its crystallization retention also drops sharply, while the zeolite produced by the present invention can maintain a unit cell shrinkage similar to that of the comparison zeolite. , and the degree of decrease in crystal retention is also small. (See Table 1 at the end of the text)

Example 5-8

1. prepare zeolite by the inventive method

Take the comparative sample A-comparison prepared in the second part of Example 1, and prepare zeolites E, F, G and H according to the first part method of Examples 1-4 respectively.

2. Preparation of comparative zeolite samples by conventional hydrothermal method

Get the comparative sample A-contrast obtained in the second part of Example 1, and prepare the comparative zeolite samples E-contrast, F-contrast, G-contrast and H-contrast by the method of the second part in examples 1-4 respectively.

3. Determination of structural parameters of zeolite

Determination of structural parameters and zeolite composition of zeolite E～H and comparison zeolite E-contrast～H-contrast by the method of example 1, the results are shown in Table 2. It can be seen from Table 2 that the increase of SO ^2- ₄ content in the filter makes the crystallization retention of the zeolite prepared by the conventional hydrothermal method drop sharply, but the zeolite produced by the present invention can maintain a higher crystallization retention. (See Table 2 at the end of the text)

Examples 9-12

One. prepare zeolite by the inventive method

(1) Take 200 grams of aluminum sulfate solution containing 5.0% by weight of Al ₂ O ₃ , and adjust its pH value with 10% by weight of ammonia water:

Example 9 10 11 12

pH 3.5 4.5 5.5 7.2

Add 90 grams of NaY zeolite (with example 1), mix well.

(2) Add an appropriate amount of ammonium sulfate and water to the resultant in step (1) to make the zeolite: ammonium sulfate: water in the slurry 1:1:10 (weight ratio), heat up to 90 ° C, and carry out 10 hours under stirring. ion exchange reaction.

(3) Use ammonia water to adjust the pH value of the slurry obtained in step (2) to 6.8, and filter.

(4) The filtered coal (solid content 40.8% by weight) obtained in step (3) was placed in a stainless steel tubular reactor and heated to 570°C, and roasted in 100% water vapor for 2.0 hours to obtain 10% by weight amorphous oxide Aluminum zeolites I, J, K and L.

2. Determination of structural parameters of zeolite

Measure the structural parameter of zeolite I～L and C with the method of example 1 Number and composition, and compared with the comparative zeolite C-comparison, the results are shown in Table 3. (See Table 3 at the end of the text)

It can be seen from the table that the zeolite prepared by the present invention maintains a unit cell shrinkage range similar to that of the comparative zeolite, and has a high degree of crystallization retention.

Examples 13-14

Prepare zeolite M and N by the method for example 3, just (3) step slurry pH value is:

Zeolite M N

pH 7.5 8.5

The structural parameters of zeolites M, N and C are shown in Table 4. (See Table 4 at the end of the text)

As can be seen from the table, the zeolite crystal retention degree produced by the present invention is relatively high.

Examples 15-19

(1) Take an appropriate amount of aluminum sulfate solution, adjust the pH value to 5.2 with ammonia water, add an appropriate amount of NaY zeolite (same as Example 1), and mix well; the specific operating conditions are:

Aluminum sulfate solution

Example The amount of NaY zeolite, grams

Concentration, weight % Dosage, grams

15 5.0 100 95

16 4.0 375 85

17 5.0 400 80

18 5.0 500 75

19 6.0 500 70

(2) Same as step (2) of Example 3.

(3) Same as step (3) of Example 3.

(4) Same as step (4) of Example 3, that is, zeolite O, P, Q, R and S.

The structural parameters of zeolites O-S are shown in Table 5. It can be seen from the table that the increase of amorphous alumina content in zeolites is beneficial to improve the crystallization retention. (See Table 5 at the end of the text)

Examples 20-21

The zeolites prepared according to the invention are used as active components of catalysts.

Take zeolite C and G respectively and carry out ammonium ion exchange according to the following conditions: zeolite:ammonium sulfate:water=1:1:40, temperature 90°C, time 1 hour. Filter again, wash with 20 times of deionized water, the gained filter and press zeolite: semi-synthetic support = 30: 70 weight ratio and support mix uniformly, promptly get catalyst CAT-C and CAT-G after oven dry, wherein semi-synthetic support Contains 25% by weight (calculated as alumina) of pseudo-boehmite (produced by Shandong Aluminum Factory) and 75% by weight of kaolin (Suzhou Jixuan 2#), which is made by mixing pseudo-boehmite with an appropriate amount of hydrochloric acid, and then adding kaolin And prepared, its pH value is 2.9.

Comparative catalysts CAT-Comparative C and CAT-Comparative G were prepared by taking comparative zeolites C-Comparative and G-Comparative according to the above method.

After catalysts CAT-C, CAT-G, CAT-comparison C and CAT-comparison G were aged at 800°C and 100% steam for 4 hours, the structural parameters of the zeolite in the catalyst were shown in Table 6, as can be seen from Table 6. The obtained zeolite has a higher total crystallization retention than the zeolite produced by the conventional hydrothermal method, indicating that the zeolite produced by the present invention has higher structural stability.

The catalytic cracking reaction performance of the above-mentioned catalyst was evaluated on a standard light oil micro-reactor device. The reaction conditions: the raw material oil is Dagang straight-run diesel oil (fraction 200-300°C), the catalyst loading is 5.0 grams (20-40 mesh), and the reaction temperature 460°C, catalyst-to-oil ratio 3, weight space velocity 16 hours ^-1 , the reaction results are shown in Table 6. It can be seen from the table that the catalyst containing the zeolite prepared by the present invention has higher catalytic activity. (See Table 6 at the end of the text)

Table A

Example 1 2 3 4

Zeolite: Ammonium Sulfate: Water 1:1:40 1:1:20 1:1:10 1:1:5

Table 1

Ion exchange slurry Zeolite composition, weight % Structural parameters

Ammonium sulfate concentration unit cell constant a ₀ in zeolite

Na ₂ O Al ₂ O ₃ SO ^2- ₄ Crystal retention %

Weight % (nano)

A 2.5 3.2 30.04 1.11 2.462 98.0

B 5.0 3.3 - 2.32 2.458 93.5

C 10.0 3.4 - 4.26 2.455 89.2

D 20.0 3.3 - 8.52 2.454 85.0

A-comparison 2.5 3.6 22.20 1.01 2.461 92.0

B-Comparison 5.0 3.6 - 2.12 2.456 82.0

C-Contrast 10.0 3.8 - 4.02 2.454 76.0

D-contrast 20.0 3.7 - 8.03 2.453 70.0

Note: The degree of crystallization retention is:

Crystal retention =

(peak height of 5.3.3 crystal plane of zeolite after hydrothermal calcination)/(peak height of 5.3.3 crystal plane of zeolite before hydrothermal calcination) ×100%

Table 2

Ion exchange slurry Zeolite composition, weight % Structural parameters

Ammonium sulfate concentration unit cell constant a ₀ in zeolite

Na ₂ O Al ₂ O ₃ SO ^2- ₄ Crystal retention %

Weight % (nano)

E 2.5 1.3 29.84 1.20 2.445 94.2

F 5.0 1.2 - 2.30 2.443 91.2

G 10.0 1.1 - 4.32 2.442 85.6

H 20.0 1.2 - 8.65 2.440 79.9

E-contrast 2.5 1.4 22.30 0.98 2.446 85.0

F-contrast 5.0 1.5 - 2.02 2.442 76.8

G-contrast 10.0 1.6 - 3.98 2.438 72.0

H-contrast 20.0 1.4 - 7.95 2.436 66.0

table 3

Step (1) Sodium and sulfate content in zeolite, % by weight Structural parameters

Unit cell constant a ₀ of zeolite slurry

Na ₂ O SO ^2- ₄ crystal retention %

pH (Nano)

I 3.5 2.9 4.20 2.454 90.5

J 4.5 3.1 3.98 2.455 91.4

C 5.2 3.4 4.26 2.455 89.2

K 5.5 3.1 4.12 2.455 91.5

L 7.2 3.3 4.42 2.456 87.5

C-contrast 3.8 4.02 2.454 76.0

Table 4

Step (3) Content of sodium and sulfate radicals in zeolite, % by weight Structural parameters

Unit cell constant a ₀ of zeolite slurry

Na ₂ O SO ^2- ₄ crystal retention %

pH (Nano)

C 6.5 3.4 4.26 2.455 89.2

M 7.5 3.2 4.10 2.456 91.5

N 8.5 3.3 4.05 2.455 90.8

C-contrast 3.8 4.02 2.454 76.0

table 5

Sodium and SO ^2- ₄ content in zeolite without zeolite, weight % Structural parameter

Example zeolite shaped Al ₂ O ₃ unit cell constant a ₀

Na ₂ O SO ^2- ₄ crystal retention %

: Zeolite (nano)

15 O 5:95 3.4 4.02 2.454 86.9

3 C 10:90 3.4 4.26 2.455 89.2

16 P 15:85 3.2 4.38 2.456 90.5

17 Q 20:80 3.1 4.53 2.455 91.4

18 R 25:75 2.9 4.61 2.454 88.5

19 S 30:70 2.8 4.74 2.454 87.8

3 C-contrast 0:100 3.8 4.02 2.454 76.0

Table 6

CAT-C CAT-G CAT-Contrast C CAT-Contrast G

Unit cell constant, 2.428 2.427 2.426 2.427

a ₀ (nanometer)

Total crystal retention 62.4 66.4 44.5 41.1

Retention*, %

Microreactivity, % 52 64 53 51

*Total crystallization retention = (diffraction intensity of zeolite 5.3.3 crystal plane after catalyst aging)/(diffraction intensity of zeolite 5.3.3 crystal plane before hydrothermal calcination) × 100%

Claims (6)

1, a kind of method for preparing ultrastable is characterized in that being made up of following several steps:

(1) getting concentration is that 3～6 heavy % are (with Al ₂O ₃Meter) aluminum sulfate solution, transferring its pH value with ammoniacal liquor is 3.5～7.5, adds NaY zeolite or HNaY zeolite and makes the slurries mesolite: gluey Al ₂O ₃=95～70: 5～30 (weight ratio, butts) mix;

(2) (1) step gains mix by the conventional method of ammonium ion exchange in the Hydrothermal Preparation USY zeolite process and ammonium sulfate and water, carry out ammonium ion exchange and react;

(3) transferring the pH value of (2) step gains with ammoniacal liquor is 6.5～8.5, filters;

(4) (3) step gained are filtered and are carried out hydrothermal calcine by the conventional method of hydrothermal calcine in the Hydrothermal Preparation USY zeolite process, promptly get to contain unformed Al ₂O ₃The ultrastable of 5～30 heavy %.

2,, it is characterized in that said pH value is 3.5～5.5 in (1) step by the described method of claim 1.

3,, it is characterized in that said zeolite and gluey Al in (1) step by the described method of claim 1 ₂O ₃Ratio be 95～85: 5～15(weight ratio).

4,, it is characterized in that (2) step mesolite: ammonium sulfate: water=1: 0.8～1.5: 10～40(weight ratio) by the described method of claim 1.

5,, it is characterized in that the pH value in (3) step is 6.5～7.5 by the described method of claim 1.

6, by the described method of claim 1, it is characterized in that said HNaY zeolite in (1) step be the NaY zeolite by the conventional hydro-thermal method of preparation USY zeolite behind ammonium ion exchange and hydrothermal calcine the HNaY zeolite.