CN1019094B - Method for preparing high-silicon Y zeolite - Google Patents

Abstract

The invention relates to a method for preparing the active component of catalytic cracking catalyst - a new type of high-silica Y zeolite, that is, the unwashed crystallized NaY zeolite on the production device is chemically dealuminated under the action of inorganic acid, and then rehydrated. Heat treatment, repeat the above process in turn. In the chemical treatment again, other dealumination agents can be selected, and the ion exchange of ammonium and sodium can be carried out simultaneously during the chemical dealumination process. The method is characterized in that the process is simple, the operation is convenient, the production time is shortened, the production cost is greatly reduced, and the industrial production is more convenient.

Description

The invention relates to a method for preparing a novel high-silicon Y zeolite, which is an active component contained in a catalytic exemplified catalyst. This method is an improvement of the active ingredient preparation method described in Chinese patent application 89103386.6.

In order to improve the activity and selectivity of the catalytic cracking catalyst, the zeolite contained in it is usually modified. The known modification methods include: changing the cation of the zeolite by ion exchange and improving the silicon-aluminum ratio of the zeolite through the skeleton modification of the zeolite. , the method has: hydrothermal treatment system ultra-stable Y zeolite (USY) (referring to US, 3293192, 4036739); chemical dealumination system framework silicon-rich Y zeolite (FSEY) (referring to EP, 82111, US, 4503023); chemical dealumination with water Combination of heat treatment and alternate use to prepare a new type of high silica Y zeolite (NHSY) (refer to Chinese patent application 89103386.6).

The method of the present invention is similar to the method described in Chinese patent application 89103386.6, and also adopts a treatment process in which chemical dealumination and hydrothermal treatment are combined and used alternately. But the inventive method: (1) the zeolite used can be crystallized NaY without washing in industrial production. (2) Use inorganic acid as a dealumination agent in the chemical dealumination process; or at least conduct a chemical dealumination process under the action of inorganic acid first, and choose other dealumination agents when alternate chemical treatment again; or use inorganic acid and Other dealumination agents can be used interchangeably. The obtained novel high silica zeolite still has the similar characteristics disclosed in Chinese patent application 89103386.6. The method of the invention has the advantages of simple technological process, convenient operation, greatly reduced production cost and shortened production time, and is more suitable for use under existing production and equipment conditions. And it is conducive to expanding production on the original basis.

It is well known that directly synthesized NaY zeolite has poor acid resistance and its structure is easily destroyed by acid. But the method of the present invention can avoid the destructive action of acid, and the obtained high-silica Y zeolite still has very high relative crystallinity, and has the similar performance disclosed in Chinese patent application 89103386.6, and the fluidized catalytic cracking Catalyst activity and selectivity are similar.

The inventive method comprises:

(1) The zeolite raw material adopted is unwashed crystallized NaY zeolite on industrial production equipment, and the mother liquor contained therein is equivalent to NaY zeolite containing SiO ₂ 5-10% (weight) or uses NaY zeolite without mother liquor, its SiO ₂ /Al ₂ O ₃ is greater than 4.0, preferably greater than 4.5.

(2) Chemical dealumination of the above-mentioned raw materials, using inorganic acid as a dealumination agent, sulfuric acid, hydrochloric acid or nitric acid can be used, the dosage is generally 0.1-1.2 moles of H ⁺ per mole of zeolite aluminum, preferably 0.5-1.0 moles; acid The concentration is generally 0.5-5N, preferably 2-4N; the reaction temperature is generally 25-100°C, preferably 50-95°C; the reaction time is 0.5-3 hours, preferably 1-2 hours. In exchange, ammonium ions are used to replace sodium ions in the zeolite, and the prepared NH ₄ Y zeolite can also be exchanged with a rare earth solution in a conventional method, so that the zeolite contains 1-3% (weight) of _RE2 O ₃ . In another chemical dealumination, inorganic acid or other dealumination agents can be used (refer to Chinese patent application 89103386.6), or inorganic acid and other dealumination agents can be used alternately at will.

(3) Subsequent hydrothermal treatment, the temperature is generally 400-700°C, preferably 500-600°C, the water concentration in the atmosphere is generally 20-100% (volume), or 30-50% (weight) water The zeolite itself is vaporized by water, and the treatment time is generally 1-3 hours. The process of (2) and (3) can be repeated in turn, the number of repetitions and which process to terminate the process depends on the requirements of the product.

The main features of the novel high-silicon Y zeolite prepared by the inventive method are: 1. There are few aluminum vacancies in the zeolite framework structure; 2. The distribution of aluminum on the inner and outer surfaces of the zeolite is relatively uniform; The amount of aluminum "fragments" can be controlled arbitrarily; 4. The zeolite has a developed secondary pore structure; 5. The sodium content of the zeolite is low; 6. The silicon-aluminum ratio or unit cell constant of the zeolite framework is easier to control. These characteristics make the zeolite have high thermal stability and hydrothermal stability, high catalytic activity and strong selectivity. The above characteristics can be measured by the method introduced in Chinese patent application 89103386.6. The fluid catalytic cracking catalyst prepared from the zeolite has higher activity and selectivity. See Table 1-6 and Figure 1-6. (See Table 1-6)

In order to illustrate the present invention more clearly, the following examples are listed, but they do not limit the scope of the present invention in any way.

Example 1

Take 240 grams of NaY slurry containing crystallization mother liquor (including 75 grams of NaY (dry basis)), add 100 grams of ammonium sulfate, add 1000 ml of water for beating, add 140 ml of 1M H ₂ SO ₄ , heat to 95-100 ° C, stir for 1 hour, filter, wash with water, and roast the wet filter cake with about 45% water at 600°C for 2 hours; grind the roasted product finely, add 75 grams of ammonium sulfate, add 750 ml of water for beating, add 85 ml of 1M H ₂ SO ₄ , heat to 95-100 ℃, stirred for 1 hour, filtered, washed with water, and the wet filter cake was roasted at 600 °C for 2 hours; the roasted product was weighed, and treated with 2% NH ₄ F solution at 95-100 °C according to the ratio of 1 gram of solid to 10 ml of solution 1 hour. Filtrate and wash with water; exchange once with ammonium sulfate solution according to the conventional method, and dry the washed filter cake at 120°C to obtain a new type of high-silicon Y zeolite-NHSY-E. The main analysis results are as follows: (Table 1-1 see the text below )

Example 2

Take 650 grams of NaY (dry basis SiO ₂ /Al ₂ O ₃ =5.3), add 650 grams of ammonium sulfate, add 6.5 liters of water for beating, add 1M H ₂ SO ₄ 420 ml, heat up to 95-100°C, stir for 1 hour, filter, Wash with water, roast the wet filter cake at 600°C for 2 hours; finely grind the roasted product, add 610 grams of ammonium sulfate, add 6.1 liters of water for beating, add 680 ml of 1MH ₂ SO ₄ , heat to 95-100°C, stir for 1 hour, filter, wash with water, The wet filter cake was roasted at 600°C for 2 hours, and then exchanged with ammonium sulfate solution once according to the conventional method, and the washed filter cake was dried at 120°C to obtain the product NHSY-E. The main analysis results are as follows: (Table 2-1 see text)

Example 3

Take 30 grams of NaY (dry basis SiO ₂ /Al ₂ O ₃ =5.2), add 24 grams of NH ₄ Cl, add 300 ml of water for beating, heat up to 95-100°C, slowly add 60 ml of 1N HCl, and continue stirring after the addition is complete 1 hour, filter, wash with water, and bake the wet filter cake at 600°C for 2 hours; repeat the above process again to obtain the product NHSY-D, the main analysis results are as follows: (Table 3-1 see the text below)

Example 4

Take 2170 grams of NaY slurry containing crystallization mother liquor (including 650 grams of NaY (dry basis)), add 6.5 liters of water, add 650 grams of ammonium sulfate, stir and beat, add 1M H ₂ SO ₄ 950 ml, heat to 95-100 ° C, stir 1 hour, filter, wash with water, and bake the wet filter cake at 600°C for 2 hours. The above process is repeated once again, but the amount of _H2SO4 added is reduced by 1/4; the roasted product is treated with 2% _NH4F solution at 95-100 ° _C for 1 hour at a ratio of 10 ml per gram of solid, and filtered. Wash with water; exchange it once with ammonium sulfate solution according to the conventional method, and dry the washed filter cake at 120°C to obtain the product NHSY-E. The main analysis results are as follows: (see the text for Table 4-1)

Example 5

Take 17 kg of NaY slurry containing crystallization mother liquor (including 5 kg of NaY (dry basis)), add 36 liters of water, add 5 kg of ammonium sulfate for beating, add 2MH ₂ SO ₄ 3670 ml, heat up to 95-100 ° C, stir for 1 hour, filter, wash with water, and bake the wet filter cake at 600°C for 2 hours. The above process is repeated once more. The roasted product was exchanged once with ammonium sulfate according to the conventional method, and then treated with 2% NH ₄ F solution at 95-100°C for 1 hour at 10 ml per gram of solid, filtered, washed with water, and dried at 120°C to obtain the product NHSY-E. The main analysis results are as follows: (see Table 5-1 at the end of the article)

Take part of the NHSY-E prepared above, and exchange it once with a rare earth chloride solution according to the conventional method, so that the zeolite contains _RE2O3 1.5% by weight. The _zeolite containing rare earth is numbered NHSY-ER _E.

The zeolite NHSY-E and NHSY-ER _E prepared above are mixed with the matrix respectively to prepare a fluidized catalytic cracking catalyst, so that the catalyst FE ₁ contains NHSY-E25% (weight), and the catalyst FE contains NHSY-E30% (weight) , Catalyst FE ₂ containing NHSY-ER _E 25% (weight). The preparation process is as follows:

After the zeolite is finely ground, it is mixed with water glass (the provided SiO ₂ is equivalent to 65% of the weight of the matrix) for beating, and aluminum sulfate is added (the supplied Al ₂ O ₃ is equivalent to 25% of the weight of the matrix) to form a gel, and after aging, add aluminum partial Na2SO4, aged again, finally adding aluminum sulfate to make the system pH = 3-4, then adding ammonia water to adjust the pH = 5-6, after the gel was homogeneously milled, spray-dried, the obtained microspheres were sieved and then washed with water to remove salt. Catalyst analysis results are as follows: (see Table 6-1 after the text)

Example 6

For comparison, a fluid catalytic cracking catalyst containing FSEY zeolite was prepared as a comparative catalyst. First prepare FSEY with ammonium fluorosilicate dealumination agent.

Take 560 grams of NH ₄ Y (dry basis, SiO ₂ /Al ₂ O ₃ =5.3) with an exchange degree of NH ⁺ ₄ of 80%, add 65 liters of water, add 650 grams of ammonium acetate, make a slurry, heat up to 60-65°C, and Add 5280 ml of 5% ammonium fluorosilicate solution slowly to the system, heat up to 80°C after about 4 hours, stir for 2 hours, then heat up to 90°C and stir for 2 hours, filter, wash with hot water, and the final filter cake is fully After washing with water, dry at 120°C to obtain the product FSEY. The main analysis results are as follows: (see the text for Table 7-1)

Mix FSEY with the matrix at a ratio of 25:75 to make a fluidized catalytic cracking catalyst. The preparation procedure is the same as in Example 5. The catalyst number is F-A. The main analysis results are as follows: (Table 8-1 sees the text below)

Another comparative catalyst used in the present invention is F-O, which is a commercial fluid catalytic cracking catalyst containing USY for the cracking of residual oil to produce high-octane gasoline, and the zeolite content in the catalyst is greater than 30% by weight .

Example 7

The evaluation of the catalyst of the present invention and the comparison catalyst is carried out on a small-scale fixed fluidized bed device. Before the evaluation, the catalyst is first deactivated, and its condition is 800 ℃, 100% steam treatment for 10 hours. The operating temperature, weight hourly space velocity (WHSV) and ratio of catalyst to feedstock oil (C/O) of the evaluation unit are listed in the evaluation result table. The properties of the raw oil used in the evaluation are as follows: (Table 9-1 see the text below)

The cracking reaction product is expressed as the weight percentage (wt%) of the specific product to the feedstock, including the following hydrogen and hydrocarbons:

H ₂ hydrogen

C ₁ methane

C ₂ ethane and ethylene

C ₃ propane and propylene

C ₄ butane, isobutane and butene

Gasoline boiling point 43-220°C

Diesel boiling point 220-330℃

Heavy oil boiling point > 330°C

Coke deposits on the catalyst The coke and (or) coke predecessor definition: Gasoline yield (wt%) = weight of gasoline / weight of feedstock

Conversion rate (weight%) = weight of raw material - weight of heavy oil / weight of raw material

Gasoline selectivity (%) = gasoline (weight %)/conversion (weight %)

Coke selectivity (%) = coke (weight %)/conversion (weight %)

Dry gas selectivity (%) = H ₂ +C ₁ +C ₂ (weight %)/conversion (weight %)

C ₃ +C ₄ hydrocarbon selectivity (%)=C ₃ +C ₄ (weight %)/conversion (weight %)

The evaluation results of catalyst of the present invention and contrast catalyst are listed in table 3, 4, 5, 6 respectively, according to the data in the table, draw the gasoline yield and conversion rate contrast figure (Fig. 2) of each catalyst under the same reaction conditions, draw The relationship between the gasoline selectivity, coke selectivity, dry gas selectivity and C ₃ +C ₄ hydrocarbon selectivity of each catalyst and the conversion rate are shown in Figures 3, 4, 5 and 6. It can be seen from the data in the table that the octane number levels of the catalyst of the present invention and the comparison catalyst are similar, and the octane number of the chromatographic method is above 91. The results in Table 6 show that increasing the zeolite content or introducing a small amount of rare earth into the zeolite can increase the gasoline yield and conversion rate with the FE type catalyst. Figure 2 shows that, compared with the comparison catalyst, the gasoline yield and conversion rate of the catalyst of the present invention are higher. Figure 3 shows that the inventive catalyst has a higher gasoline selectivity than the comparative catalyst. Figure 4 shows that the coke selectivity of each catalyst is good, and the catalyst FE of the present invention is better. Figure 5 shows that the dry gas selectivity of the inventive catalyst is slightly better than that of the comparative catalyst. Figure 6 shows that the _C3 + _C4 hydrocarbon selectivity of the inventive catalyst is comparable to that of the comparative catalyst.

The above results show that the catalyst of the present invention has improved activity and selectivity, showing the superiority of the novel high silica Y zeolite (NHSY-E) prepared by the method of the present invention.

Brief description of the drawings:

Figure 1 NHSY-E with different Al "fragments" content

Aluminum "fragment" content a>b>c

Figure 2 Activity comparison of catalysts

(1) Gasoline yield on the vertical axis Weight %

(2) Conversion rate of ordinate weight %

Reaction conditions: Reaction temperature 480°C, WHSV～16.0, C/0～3.0

Figure 3 Relationship between gasoline selectivity and conversion

Figure 4 The relationship between coke selectivity and conversion

Figure 5 The relationship between dry gas selectivity and conversion

Fig.6 Relationship between C ₃ +C ₄ hydrocarbon selectivity and conversion

Properties See Table 1-6 and Figure 1-6.

Table 1 Comparison of the stability of high silica Y zeolites prepared by different methods

Before water vapor treatment After water vapor treatment

sample system

Na ₂ O Xi a. Structure collapse temperature Xi a.

preparation method

℃ % Heavy% %

℃%

Ammonium Fluosilicate 0.65 92 24.45 1086 88 24.28

Dealumination 0.43 100 24.53 1008 94 24.28

The present invention 0.20 103 24.53 1014 89 24.25

Method 0.35 95 24.47 1064 - -

Hydrothermal dehydration

Aluminum method - 93 24.45 1002 80 24.19

Note: Xi-relative crystallinity, water vapor treatment conditions: 100% water vapor 800°C for 3 hours

Table 2 Comparison of secondary pore structures of high silica Y zeolites prepared by different methods

Sample preparation a. Surface area ^* m ² /g Micropore volume

preparation method S _total S _in S _large ml/g

Ammonium Fluosilicate 24.45 727 12 27 0.251

Dealumination

The present invention 24.53 750 148 25 0.224

method

Hydrothermal desorption 24.52 759 83 7 0.253

aluminum method

）＊S _total -total surface area, S _medium -medium pores (40-200 ), S _large -large holes (>200

)

Table 3 Evaluation results of catalysts F-E

Reaction temperature °C 470 480 490 500 510

WHSV 20.73 16.20 16.00 15.04 16.27

C/O ratio 2.99 2.99 3.41 3.74 4.03

H ₂ +C ₁ +C ₂ wt% 0.7 0.8 1.0 1.2 1.4

C ₃ +C ₄ wt% 17.0 19.5 22.7 24.4 26.4

Gasoline Weight % 48.2 51.9 51.5 50.2 49.6

Diesel Weight % 17.5 15.2 12.8 13.6 13.1

Heavy Oil Weight % 14.9 10.7 9.8 8.5 7.0

Coke Weight % 1.6 1.8 2.2 2.1 2.5

Conversion Rate Weight % 85.1 89.3 90.2 91.5 92.9

Octane number (chromatographic method) 91.4 92.1 91.6 91.8

Gasoline selectivity % 56.6 58.1 57.1 54.9 53.4

Coke selectivity % 1.88 2.02 2.44 2.30 2.69

Dry gas selectivity % 0.82 0.90 1.10 1.30 1.51

C ₃ +C ₄ hydrocarbon selectivity % 20.0 21.8 25.2 26.7 28.4

Table 4 Evaluation results of catalyst F-A

Reaction temperature °C 480 490 500 510

WHSV 16.04 15.90 15.71 16.17

C/O ratio 3.00 3.41 3.77 4.03

H ₂ +C ₁ +C ₂ wt% 0.67 0.90 1.10 1.40

C ₃ +C ₄ wt% 18.2 21.6 23.6 25.6

Gasoline Weight % 46.3 49.7 50.4 50.2

Diesel Weight % 15.9 14.4 13.7 11.4

Heavy Oil Weight % 17.5 11.6 9.3 9.1

Coke Weight % 1.5 1.8 2.0 2.2

Conversion Rate Weight % 82.5 88.3 90.7 91.1

Octane number (chromatographic method) 91.4 92.2 91.0

Gasoline selectivity % 56.1 56.3 55.6 55.1

Coke selectivity % 1.82 2.04 2.21 2.41

Dry gas selectivity % 0.81 1.02 1.21 1.54

C ₃ +C ₄ hydrocarbon selectivity% 22.1 24.5 26.0 28.1

Table 5 Evaluation results of catalyst F-O

Reaction temperature ℃ 480 490 500 510 520

WHSV 15.44 16.07 15.89 15.69 14.29

C/O ratio 2.99 3.39 3.75 4.05 4.50

H ₂ +C ₁ +C ₂ wt% 0.7 1.0 1.3 1.3 1.6

C ₃ +C ₄ wt% 16.7 20.2 22.9 24.2 26.9

Gasoline Weight % 48.0 51.1 49.4 49.9 47.8

Diesel Weight % 17.6 14.6 14.7 12.3 14.3

Heavy oil weight % 15.0 10.9 9.7 ^* 9.9 7.1

Coke Weight% 1.8 2.1 2.0 2.4 2.3

Conversion Rate Weight % 85.0 89.0 90.3 90.1 92.8

Octane number (chromatographic method) 91.4 91.4 92.3 92.6 93.9

Gasoline selectivity % 56.5 57.4 54.7 55.4 51.5

Coke selectivity % 2.12 2.36 2.21 2.66 2.48

Dry gas selectivity % 0.82 1.12 1.46 1.44 1.77

C ₃ +C ₄ hydrocarbon selectivity% 19.6 22.7 25.4 26.9 29.0

Table 6 Comparison of three catalysts of F-E type

Catalyst FE ₁ FE FE ₂

Reaction temperature °C 500 500 500

WHSV 16.63 15.04 16.28

C/O ratio 3.73 3.74 3.73

H ₂ +C ₁ +C ₂ wt% 1.04 1.19 1.23

C ₃ +C ₄ weight % 23.4 24.4 24.2

Gasoline Weight % 46.8 50.2 50.3

Diesel Weight % 16.7 13.6 13.1

Heavy Oil Weight % 11.4 8.5 8.9

Coke Weight % 1.8 2.1 2.4

Conversion Rate Weight % 88.6 91.5 91.1

Octane number (chromatographic method) 91.97 91.62 90.89

Gasoline selectivity % 52.8 54.9 55.2

Coke selectivity % 2.03 2.30 2.63

Dry gas selectivity % 1.17 1.30 1.35

C ₃ +C ₄ hydrocarbon selectivity% 26.4 26.7 26.6

Table 1-1

a. Relative crystallinity % Na ₂ O% Structure collapse temperature ℃ Specific surface m ² /g

24.533 105 0.203 1014 750

table 2-1

相对结晶度% Na₂O% 结构崩塌温度℃ 比表面m²/ga.

Relative crystallinity % Na ₂ O% Structure collapse temperature ℃ Specific surface m ² /g

24.445 112 0.17 1050 820

Table 3-1

相对结晶度% Na₂O% 结构崩塌温度℃ 比表面m²/ga.

Relative crystallinity % Na ₂ O% Structure collapse temperature ℃ Specific surface m ² /g

24.461 91 0.55 1032 778

Table 4-1

相对结晶度% Na₂O% SiO₂/Al₂O₃结构崩塌温度℃ 比表面m²/ga.

Relative crystallinity % Na ₂ O% SiO ₂ /Al ₂ O ₃ structure collapse temperature ℃ Specific surface m ² /g

24.474 95 0.35 10.8 1064 766

Table 5-1

a. Relative crystallinity % Na ₂ O% Structure collapse temperature ℃ Z ^* Specific surface m ² /g

24.500 110 0.41 1035 0.032 874

Table 6-1

O₃% 比表面m²/g 孔体积ml/gCatalyst Na ₂ O% Al ₂ O ₃ % SiO ₂ %

O ₃ % specific surface m ² /g pore volume ml/g

FE ₁ 0.33 28.35 70.50 - 333 0.317

F-E 0.40 26.46 72.10 - 412 0.322

_FE2 0.21 27.19 71.26 0.34 379 0.314

Table 7-1

相对结晶度% 结构崩塌温度℃ Z 比表面m²/g Na₂O%a.

Relative crystallinity % Structure collapse temperature ℃ Z Specific surface m ² /g Na ₂ O%

24.471 99 1080 0.026 878 0.11

Table 8-1

Na ₂ O% Al ₂ O ₃ % SiO ₂ % Specific surface m ² /g Pore volume ml/g

0.44 26.90 71.25 403 0.393

Table 9-1

Viscosity L/100 4.65 (centitos) Average molecular weight 331

Carbon residue 0.276 (weight %) Initial boiling point (°C) 252

Specific gravity 0.8524 Distillation 10% (℃) 306

Refractive index 1.4924 Distillation 50% (℃) 400

Flash point 149 (°C) Distillation 90% (°C) 501

Freezing point +36 (°C) End boiling point (°C) 501

Total distillate (%) 93

Yuan S, ppm 665 gold

F ₊ (ppm) 2.8

Vegetarian

N,% 0.11 Ni (ppm) 0.3

containing

C,% 84.37 volume V (ppm) 0.05

quantity

H,% 12.74

Claims (6)

1, a kind of chemical dealumination and hydrothermal treatment process are combined and used alternately, the method for preparing novel high silicon Y zeolite, it is characterized in that, this method comprises: (1) Raw material: The raw material used is unwashed crystallized NsY zeolite on the production device (its mother liquor content is equivalent to NaY zeolite containing amorphous SiO ₂ 5-10%) or NaY zeolite without mother liquor, its SiO ₂ / The Al ₂ O ₃ ratio is greater than 4, preferably greater than 4.5. (2) Chemical dealumination process: the dealumination agent is inorganic acid; or use inorganic acid as dealumination agent first, and then choose other dealumination agents when performing alternate chemical dealumination again, and the other dealumination agents refer to ethylenediamine tetramine Acetic acid, oxalic acid, sulfosalicylic acid, ammonium oxalate, ammonium fluoride, ammonium fluorosilicate or ammonium fluoroborate, or their mixtures; or inorganic acid and other dealuminizing agents are used alternately, and the inorganic acid is used as a dealuminizing agent , the reaction temperature is 25-100°C, the acid concentration is 0.5-5N, the acid dosage is 0.1-1.2 moles of H ⁺ per mole of zeolite framework aluminum, and the reaction time is 0.5-3 hours; when other dealumination agents are used, the reaction temperature is 25 -100°C, the concentration of dealumination agent is 1-20% (weight), the amount of dealumination agent is calculated according to the required degree of pre-dealuminization, and the reaction time is 1-6 hours; (3) Hydrothermal treatment process: the treatment temperature is 400-700°C, the treatment time is 1-3 hours, the water concentration in the atmosphere is 20-100% (volume), or it can be the zeolite itself water containing 30-50% (weight) water Vaporization; (4) The chemical dealumination process and the hydrothermal treatment process of (2) and (3) are repeated in sequence. The number of repetitions and which process to terminate the treatment depend on the performance requirements of the high-silica Y zeolite. 2. The method according to claim 1, characterized in that sulfuric acid or hydrochloric acid can be selected as the inorganic acid dealumination agent, the reaction temperature is 50-95°C, the acid concentration is 2-4N, and the acid dosage is 0.5-1.0 per mole of zeolite framework aluminum. Mole H ⁺ , the reaction time is 1-2 hours; other dealumination agents can be oxalic acid, ammonium oxalate or their mixture, the reaction temperature is 50-95°C, the dealumination agent concentration is 2-10%, and the reaction time is 2-4 Hour. 3. According to the method of claim 1, it is characterized in that the chemical dealumination process and the hydrothermal treatment process are only repeated once in sequence, and the process conditions are as follows: (1) Chemical dealumination process: use a concentration of 2-4NH ₂ SO ₄ as a dealumination agent, the amount of acid is 0.5-1.0 moles of H ⁺ per mole of zeolite framework aluminum, the reaction temperature is 50-95°C, and the reaction time is 1-2 Hour; (2) Hydrothermal treatment process: the treatment temperature is 500-700°C, the treatment time is 1-3 hours, and the water concentration in the atmosphere is 20-80% (volume); (3) Chemical dealumination process: repeat (1); (4) Hydrothermal treatment process: Repeat (2). 4. According to the method of claim 1, it is characterized in that the chemical dealumination process and the hydrothermal treatment process are alternately carried out twice, and the process conditions are as follows: (1) Chemical dealumination process: use oxalic acid, ammonium oxalate or their mixture with a concentration of 2-10% (weight) as dealumination agent, the dosage is calculated according to the required pre-dealuminum degree, the reaction temperature is 50-95°C, and the reaction Time is 2-4 hours; (2) Hydrothermal treatment process: the treatment temperature is 500-700°C, the treatment time is 1-3 hours, and the water concentration in the atmosphere is 20-80% (volume); (3) Chemical dealumination process: 2-4NH ₂ SO ₄ is used as dealumination agent, the amount of acid is 0.5-1.0 mole of H ⁺ per mole of zeolite framework aluminum, and the reaction temperature is 50-95°C. Reaction time 1-2 hours; (4) Hydrothermal treatment process: Repeat (2). 5. The method according to claim 3 or 4, characterized in that a final chemical dealumination is carried out under the following conditions: with 1-5% (by weight) NH ₄ F or (NH ₄ ) ₂ C ₂ O ₄ solution, the amount Treat the zeolite at 50-100° C. for 0.5-3 hours based on 5-10 ml of solution per gram of zeolite. 6. According to the method of claim 1, 2, 3, 4 or 5, it is characterized in that, in the process of preparing high-silica Y zeolite or after making high-silica Y zeolite, the conventional methods of impregnation, precipitation or ion exchange can be used to introduce The rare earth elements make the zeolite contain RE ₂ O ₃ 1-5% by weight, preferably 1-3% by weight.

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