CN108452838B

CN108452838B - Catalytic cracking catalyst

Info

Publication number: CN108452838B
Application number: CN201710097154.0A
Authority: CN
Inventors: 周灵萍; 张蔚琳; 许明德; 陈振宇; 田辉平; 朱玉霞
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2017-02-22
Filing date: 2017-02-22
Publication date: 2020-06-16
Anticipated expiration: 2037-02-22
Also published as: CN108452838A

Abstract

A catalytic cracking catalyst comprises clay, alumina containing an additive and a modified Y-type molecular sieve, wherein the modified Y-type molecular sieve contains 5-12 wt% of rare earth, no more than 0.5 wt% of sodium oxide, the total pore volume is 0.36-0.48 mL/g, the secondary pore volume accounts for 20-38% of the total pore volume, the unit cell constant is 2.440-2.455 nm, non-framework aluminum accounts for less than 10% of the total aluminum, the lattice collapse temperature is higher than 1060 ℃, and the ratio of the B acid amount to the L acid amount is not lower than 3.50. The preparation method comprises the following steps: preparing a Y-type molecular sieve containing rare earth and having a conventional unit cell size, roasting for 4.5-7 hours at 350-520 ℃ in a 30-95 volume% water vapor atmosphere, carrying out contact reaction with silicon tetrachloride gas, and carrying out acid treatment. The catalytic cracking catalyst has higher heavy oil conversion activity, lower coke selectivity, higher gasoline yield, liquefied gas yield, light oil yield and total liquid yield.

Description

Catalytic cracking catalyst

Technical Field

The present invention relates to a catalytic cracking catalyst.

Background

The Y-type molecular sieve has been the main active component of catalytic cracking (FCC) catalysts since its first use in the last 60 th century. However, as crude oil heavies increase, the content of polycyclic compounds in the FCC feedstock increases significantly, and their ability to diffuse through the zeolite channels decreases significantly. The aperture of the Y-type molecular sieve as the main active component is only 0.74nm, and the Y-type molecular sieve is directly used for processing heavy fractions such as residual oil and the like, and the accessibility of the active center of the catalyst can become a main obstacle for cracking polycyclic compounds contained in the Y-type molecular sieve.

The molecular sieve pore structure has close relation with the cracking reaction performance, especially for a residual oil cracking catalyst, the secondary pores of the molecular sieve can increase the accessibility of residual oil macromolecules and active centers thereof, and further improve the cracking capability of residual oil.

The hydrothermal dealumination process is one of the most widely used in industry, and includes the first exchange of NaY zeolite with water solution of ammonium ion to reduce the sodium ion content in zeolite, and the subsequent roasting of the ammonium ion exchanged zeolite at 600-825 deg.c in water vapor atmosphere to stabilize the zeolite. The method has low cost and is easy for industrialized mass production, and the obtained ultrastable Y-type zeolite has rich secondary pores, but the loss of the crystallinity of the ultrastable Y-type zeolite is serious.

At present, the industrial production of ultrastable Y-type zeolite is generally an improvement on the above-mentioned hydrothermal roasting process, and adopts twice exchange and twice roasting method, and its goal is to adopt milder roasting condition step by step so as to solve the problem of serious loss of crystallinity produced under the harsh roasting condition.

US5,069,890 and US5,087,348 disclose a method for preparing a mesoporous Y-type molecular sieve, which mainly comprises the following steps: commercially available USY was used as a starting material and treated at 760 ℃ for 24 hours in an atmosphere of 100% steam. The mesoporous volume of the Y-type molecular sieve obtained by the method is increased from 0.02mL/g to 0.14mL/g, but the crystallinity is reduced from 100 percent to 70 percent, and the surface area is 683m²The/g is reduced to 456m²The acid density drops sharply from 28.9% to 6% even more.

In the method for preparing the mesoporous-containing Y-shaped molecular sieve disclosed in US5,601,798, HY or USY is taken as a raw material and is put into an autoclave to react with NH₄NO₃Solution or NH₄NO₃With HNO₃The mixed solution is mixed and treated for 2 to 20 hours at the temperature of 115 to 250 ℃ higher than the boiling point, the volume of the mesoporous of the obtained Y-shaped molecular sieve can reach 0.2 to 0.6ml/g, but the crystallinity and the surface area are obviously reduced.

CN201310240740.8 discloses a combined modification method of a rich-mesoporous ultrastable Y molecular sieve, which is characterized in that organic acid and inorganic salt dealuminization reagents are added simultaneously in the modification process to carry out combined modification of organic acid and inorganic salt, and the optimal process conditions of optimal concentration, volume ratio, reaction time, reaction temperature and the like of organic acid and inorganic salt solution are determined through orthogonal experiments. Compared with an industrial USY molecular sieve, the USY obtained by the method has the advantages that the secondary pore content is obviously improved, higher crystallinity can be maintained, the silicon-aluminum ratio is increased, the unit cell constant is reduced, and the molecular sieve is suitable for a high and medium oil type hydrocracking catalyst carrier.

CN1388064 discloses a process for preparing high-silicon Y zeolite with a unit cell constant of 2.420-2.440 nm (Dow; Li Xuan Wen; Li Da Dong; Scheinen; Niehr; Shiyawa), which comprises subjecting NaY zeolite or Y-type zeolite which has been subjected to a superstabilization treatment to one or more of ammonium exchange, hydrothermal treatment and/or chemical dealumination; characterized in that at least the first ammonium exchange in the ammonium exchange before the hydrothermal treatment and/or chemical dealumination is a low-temperature selective ammonium exchange at room temperature to below 60 ℃, and the rest of the ammonium exchanges are either low-temperature selective ammonium exchanges at room temperature to below 60 ℃ or conventional ammonium exchanges at 60-90 ℃. The high-silicon Y zeolite prepared by the patent still has higher crystal retention degree when the unit cell constant is smaller, and simultaneously has more secondary holes, and is suitable for being used as a middle distillate oil hydrocracking catalyst.

Although the ultrastable Y molecular sieve prepared by the method disclosed in the above patent contains a certain amount of secondary pores, has a small unit cell constant and a high Si/Al ratio, these modified molecular sieves are suitable for hydrogenation catalysts, and it is difficult to meet the high cracking activity requirement required for processing heavy oil by catalytic cracking.

CN1629258 discloses a preparation method of a cracking catalyst containing rare earth ultrastable Y-type molecular sieve (mu Xuhong; Wang Ying; Shuxintian; Robin; Zongning; He Ming Yuan; Wujia; Wang Xuan), which is characterized in that the method comprises the step of contacting a NaY molecular sieve with an ammonium salt aqueous solution containing 6-94 wt% of ammonium salt twice or more according to the weight ratio of 0.1-24 of ammonium salt to the molecular sieve under the conditions of normal pressure and the boiling temperature of more than 90 ℃ and not more than the boiling point temperature of the ammonium salt aqueous solution, so that Na in the molecular sieve is obtained by contacting the molecular sieve with the ammonium salt aqueous solution twice or more₂Reducing the O content to below 1.5 wt%, and then using rare earth saltContacting the 2-10 wt% water solution with the molecular sieve at 70-95 deg.C to make the rare earth in the molecular sieve as RE₂O₃0.5-18 wt%, and mixing with carrier and drying. In the preparation process of the molecular sieve, multiple ammonium salt exchanges are needed, the preparation process is complicated, the ammonia nitrogen pollution is serious, and the cost is high. In addition, the molecular sieve has low degree of ultrastability, low silicon-aluminum ratio and less secondary pores.

CN1127161 discloses a method for preparing a rare earth-containing silicon-rich ultrastable Y-type molecular sieve (Dujun; plum-Caesalpinia, plum-Juta, Helianliang; Shamegnan), which takes NaY as a raw material and adopts solid RECl₃In the presence of SiCl₄And carrying out gas-phase dealuminization and silicon supplementation reaction to complete the ultra-stabilization of NaY and the rare earth ion exchange in one step. The unit cell constant a of the molecular sieve prepared by the method_o2.430-2.460 nm, rare earth content of 0.15-10.0 wt%, and Na₂The O content is less than 1.0 wt%. However, the molecular sieve is prepared only by a gas phase ultrastable method, and although the ultrastable Y molecular sieve containing rare earth can be prepared, the prepared molecular sieve is lack of secondary pores.

CN1031030 discloses a preparation method of a low rare earth content ultrastable Y-type molecular sieve, which provides a low rare earth content ultrastable Y-type molecular sieve for hydrocarbon cracking, and the method is prepared by using a NaY-type molecular sieve as a raw material through the steps of primary mixed exchange of ammonium ions and rare earth ions, stabilization treatment, removal of part of framework aluminum atoms, thermal or hydrothermal treatment and the like. Rare earth content (RE) of the molecular sieve₂O₃) 0.5 to 6 wt% of SiO₂/Al₂O₃Up to 9 to 50, unit cell constant a₀2.425 to 2.440 nm. The ultrastable molecular sieve prepared by the method has high silicon-aluminum ratio and small unit cell constant, contains a certain amount of rare earth, but does not relate to the preparation of a high-stability molecular sieve in a molecular sieve with secondary pores, and has poor accessibility of an active center and low activity.

The inventor of the invention finds that the catalytic cracking catalyst containing the ultra-stable Y-type molecular sieve prepared by the prior art is difficult to have higher catalytic cracking activity of heavy oil and better coke selectivity at the same time.

Disclosure of Invention

One of the technical problems to be solved by the invention is to provide a catalytic cracking catalyst suitable for heavy oil catalytic cracking processing, which contains a modified Y-type molecular sieve (the Y-type molecular sieve is also called Y-type zeolite), and the catalyst has higher heavy oil cracking activity and better coke selectivity. The second technical problem to be solved by the invention is to provide a preparation method of the catalytic cracking catalyst.

The invention provides a catalytic cracking catalyst, which comprises 10-50 wt% of modified Y-type molecular sieve, 2-40 wt% of alumina containing additive and 10-80 wt% of clay on a dry basis, wherein the weight of the catalyst is taken as a reference; the additive-containing alumina contains 60-99.5 wt% of alumina and 0.5-40 wt% of additive on a dry basis, the additive is selected from one or more of compounds containing alkaline earth metal, lanthanide metal, silicon, gallium, boron or phosphorus, the modified Y-type molecular sieve contains 5-12 wt% of rare earth oxide and sodium oxide (Na)₂O content) of not more than 0.5 wt%, for example, 0.05 wt% to 0.5 wt%, a total pore volume of 0.36mL/g to 0.48mL/g, for example, 0.38 mL/g to 0.45mL/g, a pore volume of secondary pores having a pore diameter of 2nm to 100nm of the modified Y-type molecular sieve of 20% to 38% of the total pore volume, a unit cell constant of 2.440nm to 2.455nm, a non-framework aluminum content of the modified Y-type molecular sieve of not more than 10% of the total aluminum content, a lattice collapse temperature of not less than 1060 ℃, and a ratio of the B acid amount to the L acid amount of the total acid amount of the modified Y-type molecular sieve measured at 200 ℃ by a pyridine adsorption infrared method of not less than 3.50.

The modified Y-type molecular sieve provided by the invention has the lattice collapse temperature of not less than 1060 ℃, preferably, the lattice collapse temperature of the molecular sieve is 1060-1085 ℃, for example, 1064-1081 ℃.

In the catalytic cracking catalyst provided by the invention, the ratio of the B acid amount to the L acid amount in the total acid amount of the modified Y-type molecular sieve measured at 200 ℃ by using a pyridine adsorption infrared method is preferably 3.5-6, for example, 3.6-5.5, 3.5-5, or 3.5-4.6.

In the catalytic cracking catalyst provided by the invention, the unit cell constant of the modified Y-type molecular sieve is 2.440-2.455 nm, such as 2.442-2.453 nm or 2.442-2.451 nm.

In the catalytic cracking catalyst provided by the invention, the modified Y-type molecular sieve is a high-silicon Y-type molecular sieve, and the framework silicon-aluminum ratio (SiO) of the modified Y-type molecular sieve₂/Al₂O₃Molar ratio) of 7 to 14, for example 8.5 to 12.6 or 8.7 to 12.

In the catalytic cracking catalyst provided by the invention, the percentage of non-framework aluminum content in the modified Y-type molecular sieve in the total aluminum content is not higher than 10%, for example, 5-9.5% or 6-9.5%.

In the catalytic cracking catalyst provided by the invention, the modified Y-type molecular sieve has a crystal retention of 38% or more, for example, 38-65%, 46-60% or 52-60% after aging for 17 hours at 800 ℃ under normal pressure and in a 100 volume% steam atmosphere. The normal pressure is 1 atm.

In the catalytic cracking catalyst provided by the invention, the relative crystallinity of the modified Y-type molecular sieve is not less than 70%, for example, 70-80%, preferably, the relative crystallinity of the modified Y-type molecular sieve provided by the invention is not less than 71%, for example, 71-77%.

The catalytic cracking catalyst provided by the invention has an embodiment that the specific surface area of the modified Y-type molecular sieve is 600-680 m²The/g is, for example, 610 to 670m²/g or 640-670 m²/g。

In the catalytic cracking catalyst provided by the invention, preferably, the total pore volume of the modified Y-type molecular sieve is 0.36-0.48 mL/g, such as 0.38-0.45 mL/g or 0.38-0.42 mL/g.

In the catalytic cracking catalyst provided by the invention, the pore volume of the secondary pore of the modified Y-type molecular sieve with the pore diameter of 2.0-100 nm is 0.08-0.18 mL/g, for example, 0.10-0.16 mL/g.

In the catalytic cracking catalyst provided by the invention, the pore volume of the modified Y-type molecular sieve with the secondary pores with the pore diameter (diameter) of 2-100 nm accounts for 20-38% of the total pore volume, and preferably 28-38% or 25-38%. The ratio of the pore volume of secondary pores with the pore diameter of 8nm to 100nm (the total volume of pores with the pore diameter of 2nm to 100 nm)/the pore volume of total secondary pores (the total volume of pores with the pore diameter of 2nm to 100nm) in the modified Y-type molecular sieve is 40 to 80 percent, such as 45 to 75 percent or 55 to 77 percent.

In the catalytic cracking catalyst provided by the invention, the modified Y-shaped molecular sieve contains rare earth elements, and RE is used in the modified Y-shaped molecular sieve₂O₃The content of the rare earth oxide is 5 to 12 wt%, preferably 5.5 to 10 wt%.

In the catalytic cracking catalyst provided by the invention, the content of sodium oxide in the modified Y-type molecular sieve is not more than 0.5%, and can be 0.05-0.5 wt%, for example, 0.1-0.4 wt% or 0.15-0.3 wt%.

The catalytic cracking catalyst provided by the invention contains 10-50 wt% of modified Y-type molecular sieve based on dry basis, preferably, the content of the modified Y-type molecular sieve is 15-45 wt%, for example, 20-40 wt% or 25-35 wt%.

The catalytic cracking catalyst provided by the invention can also contain clay, and the content of the clay is not more than 70 wt%, preferably 10-70 wt% based on the weight of the catalytic cracking catalyst. The clay is selected from one or more of clays used as cracking catalyst component, such as one or more of kaolin, halloysite, montmorillonite, diatomaceous earth, halloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite, and bentonite. These clays are well known to those of ordinary skill in the art. The content of the clay in the catalytic cracking catalyst provided by the invention can be 20-55 wt% or 30-50 wt% on a dry basis.

The catalytic cracking catalyst contains alumina containing additive, and the content of the alumina containing additive is 2-40 wt%, preferably 2-20 wt% on a dry basis. The alumina containing additives can be prepared according to the methods described in patents CN1915486A, CN1915485A and CN 1916116A. Preferably, the additive-containing alumina contains 70 wt% to 95 wt% of alumina based on the dry weight of the additive-containing alumina, and 5 wt% to 30 wt% of the additive based on the dry weight of the additive-containing alumina. Wherein said additive is preferably a phosphorus and/or magnesium containing compound.

The dry weight is the weight of the solid product obtained by calcining the material at 800 ℃ for 1 hour.

Preferably, the preparation method of the alumina containing the additive comprises the following steps:

(1) mixing pseudoboehmite with water and acid sufficient to cause slurrification thereof under agitation, wherein the acid is used in an amount such that the weight ratio of the acid to alumina in the pseudoboehmite is 0.01 to 0.5;

(2) aging the mixed slurry obtained in the step (1) at room temperature to 90 ℃ for 0 to 24 hours;

(3) mixing the product of step (2) with additives, optionally drying and optionally calcining.

In the method for preparing alumina containing additive, the acid in the step (1) is used in an amount that the weight ratio of the acid to the alumina in the pseudo-boehmite is 0.05-0.3. The slurrying in the step (1) enables the solid content of the slurry formed by the pseudo-boehmite and the water to be 10-50 wt%, and preferably 15-30 wt%. The acid is selected from one or more of inorganic acid and organic acid, for example, the inorganic acid can be one or more of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid, the organic acid can be one or more of formic acid, acetic acid, oxalic acid or itaconic acid, and hydrochloric acid or nitric acid is preferred.

In the preparation method of the alumina containing the additive, preferably, the aging temperature in the step (2) is between room temperature and 80 ℃, the room temperature is, for example, between 15 and 40 ℃, and the aging time is between 0.5 and 4 hours. The mixture formed by the product of step (2) and the additive in step (3) can be directly used for preparing the catalytic cracking catalyst, namely, the formed mixture is mixed with other components forming the catalytic cracking catalyst, and can also be dried and calcined for preparing the catalyst. Such as drying, spray drying.

In one embodiment of the method for preparing the additive-containing alumina, the calcination temperature in the step (3) is 350 to 800 ℃, for example, 400 to 600 ℃, and the calcination time is, for example, 0.5 to 8 hours. The additive is selected from one or more of compounds containing alkaline earth metal, lanthanide metal, silicon, gallium, sheds or phosphorus elements, the compounds containing the alkaline earth metal, copper metal, silicon, gallium, sheds or phosphorus elements can be oxides and hydrated oxides of the elements, such as magnesium oxide and magnesium hydroxide in the alkaline earth metal, rare earth oxide in the lanthanide metal, silicon oxide, silica sol and phosphorus oxide, and also can be salts containing the elements, such as nitrate in the alkaline earth metal, rare earth chloride in the lanthanide metal, silicate and phosphate. When the additive is an oxide of the element and/or a water-containing oxide, the mixing is to directly mix the product obtained in the step 2 with the additive; when the additive is one or more of salts containing the elements, the mixing is preferably performed by firstly preparing the salts into an aqueous solution and then mixing the aqueous solution with the product obtained in the step (2). The mixing in each step can be accomplished by any of a variety of methods known in the art, preferably under conditions sufficient to slurry the material (e.g., pseudoboehmite, additives), which are well known to those skilled in the art, including the introduction of water in an amount sufficient to slurry the material, typically in an amount of from 10 to 50 weight percent, preferably from 15 to 30 weight percent, of the slurry solids.

The catalytic cracking catalyst of the present invention preferably further comprises an alumina binder, wherein the content of the alumina binder is not more than 32 wt%, and preferably 5 to 32 wt%, based on the weight of the catalyst, based on the weight of alumina, the alumina binder is selected from one or more of alumina, hydrated alumina and alumina sol in various forms commonly used in cracking catalysts, for example, one or more selected from gamma-alumina, η -alumina, theta-alumina, chi-alumina, pseudoboehmite (pseudoboehmite), Boehmite (Boehmite), Gibbsite (Gibbsite), Bayerite (bayer) or alumina sol, preferably pseudoboehmite and/or alumina sol, for example, the catalytic cracking catalyst comprises 2 to 15 wt%, preferably 3 to 10 wt%, based on a dry basis, of alumina sol binder, and 10 to 30 wt%, preferably 15 to 25 wt%, based on a dry basis, of pseudoboehmite binder.

Preferably, the total content of the alumina binder and the alumina containing additive in the catalyst of the present invention is 10 wt% to 40 wt%, for example 20 to 35 wt%, and the content of the alumina containing additive is 2 wt% to 20 wt%, based on the weight of the catalyst.

The catalyst of the present invention preferably comprises, based on the weight of the catalyst: 10 to 50 wt%, such as 15 to 45 wt% or 25 to 40 wt% of the modified Y-type molecular sieve on a dry basis, and 50 to 90 wt%, such as 55 to 85 wt% or 60 to 75 wt% of a matrix on a dry basis. The matrix comprises the additive-containing alumina, clay and optionally a binder, preferably an alumina binder.

The catalyst provided by the invention can also contain other molecular sieves besides the modified Y-type molecular sieve, wherein the other molecular sieves are selected from the molecular sieves used in the catalytic cracking catalyst, such as one or more of zeolite with MFI structure, Beta zeolite, other Y-type zeolite and non-zeolite molecular sieve, the content of the other molecular sieves can be 0-40 wt% such as 0-30 wt% or 1-20 wt%, preferably, the content of the other Y-type molecular sieves is not more than 40 wt% such as 1-40 wt% or 0-20 wt% based on the dry basis, the content of the other Y-type zeolite such as one or more of REY, REHY, DASY, SOY and PSRY, the MFI structure zeolite such as one or more of H5, ZRP and ZSP, the Beta zeolite such as H β, the non-zeolite molecular sieves such as aluminum phosphate molecular sieve (AlPO molecular sieve), and silicoaluminophosphate molecular sieve (SAPO molecular sieve), and the content of the other molecular sieves is not more than 20 wt% based on the weight of the catalyst.

The preparation methods of the catalyst of the present invention are the existing methods, and the preparation methods are described in detail in patents CN1916116A, CN1362472A, CN1727442A, CN1132898C, CN1727445A and CN1098130A, which are incorporated herein by reference. Typically comprising the steps of forming a slurry comprising the modified Y-type molecular sieve, a binder, clay and water, spray drying, optionally washing and drying. Spray drying, washing and drying are the prior art, and the invention has no special requirements. For example, a preparation method comprises the steps of mixing and pulping the modified Y-type molecular sieve, alumina containing additives, clay, optional alumina binder and water, spray drying, washing, filtering and drying.

The invention provides a preparation method of a catalytic cracking catalyst, which comprises the steps of preparing a modified Y-type molecular sieve, forming slurry comprising the modified Y-type molecular sieve, alumina containing additives, clay, water and optional alumina binder, and spray drying, wherein the preparation method of the modified Y-type molecular sieve comprises the following steps:

(1) contacting NaY molecular sieve with rare earth solution to perform ion exchange reaction, filtering and washing to obtain the product

A rare earth-containing Y-type molecular sieve of conventional unit cell size with reduced sodium oxide content; wherein the rare earth solution is also called

A rare earth salt solution;

(2) modifying said rare earth-containing Y-type molecular sieve of conventional unit cell size with reduced sodium oxide content

Treating, optionally drying to obtain Y-type molecular sieve with reduced unit cell constant, and modifying

The rare earth-containing Y-type molecular sieve with the conventional unit cell size and the reduced sodium oxide content is prepared at the temperature of 350-520℃,

An atmosphere containing 30 to 95 vol% of water vapor (also referred to as an atmosphere containing 30 to 95 vol% of water vapor or referred to as an atmosphere containing 30 to 95 vol% of water

Steam) for 4.5 to 7 hours; wherein the unit cell constant is reduced in water of the Y-type molecular sieve sample

The content is preferably not more than 1% by weight; if the water content in the Y-shaped molecular sieve obtained by the modification treatment in the step (2) is

In an amount of more than 1% by weight, and the step (2) further comprises drying the mixture to a water content of less than 1% by weight; drying method

The formula is drying by adopting a roasting mode, the roasting temperature is 450-650 ℃, and the drying temperature is in the air of dry air

Drying in an atmosphere (water vapor content less than 1 wt.%) for 1 to 5 hours or 2 to 4 hours,

to a water content of less than 1% by weight;

(3) reducing the unit cell constant of the Y-type molecular sieve and SiCl₄Carrying out gas contact reaction; wherein the preferable contact reaction temperature is 200-650 ℃, SiCl₄: the weight ratio of the Y-type molecular sieve with reduced unit cell constant obtained in the step (2) on a dry basis is 0.1-0.7: 1, reacting for 10 minutes to 5 hours, and then optionally washing and optionally filtering to obtain the gas-phase ultra-stable modified Y-type molecular sieve;

(4) and (4) contacting the gas-phase ultra-stable modified Y-shaped molecular sieve obtained in the step (3) with an acid solution for modification.

The catalytic cracking catalyst provided by the invention has high thermal and hydrothermal stability, high activity and good coke selectivity, is used for heavy oil catalytic cracking, has higher heavy oil conversion activity and lower coke selectivity compared with the existing cracking catalyst, and has higher gasoline yield, light oil yield and total liquid yield.

The preparation method of the catalytic cracking catalyst, which is provided by the invention, can prepare the high-silicon Y-type molecular sieve which is rich in secondary pores and has high crystallinity, high thermal stability and high hydrothermal stability, can ensure that the molecular sieve has higher crystallinity under the condition of greatly improving the hyperstability degree, the prepared molecular sieve has uniform aluminum distribution, less non-framework aluminum content and smooth secondary pore channels, and has higher specific surface area under the condition of having higher secondary pores, the prepared catalyst is used for heavy oil conversion, the coke selectivity is good, the heavy oil cracking activity is high, and the gasoline yield, the liquefied gas yield and the total liquid yield of the molecular sieve used for heavy oil conversion can be improved.

Detailed Description

The catalytic cracking catalyst provided by the invention contains 10-50 wt% of the modified Y-type molecular sieve based on the weight of the catalyst, 2-40 wt% of the alumina containing additive based on the weight of the catalyst, 0-40 wt% of alumina binder based on the weight of the catalyst, and 10-80 wt% of clay based on the weight of the catalyst. Preferably, the catalytic cracking catalyst contains 25 to 40 wt% of the modified Y-type molecular sieve on a dry basis, 2 to 20 wt% of the additive-containing alumina on a dry basis, 5 to 30 wt% of an alumina binder on a dry basis, and 30 to 50 wt% of clay on a dry basis, and the total content of the alumina binder and the additive-containing alumina is 20 to 35 wt%.

The catalytic cracking catalyst provided by the invention contains a modified Y-type molecular sieve, and in one embodiment, the modified Y-type molecular sieve provided by the invention has the rare earth oxide content of 5-12 wt%, preferably 5.5-10 wt%, the sodium oxide content of 0.05-0.5 wt%, for example 0.1-0.4 wt% or 0.15-0.3 wt%, preferably less than 0.2 wt%, the total pore volume of 0.4-0.48 mL/g, the percentage of the pore volume of secondary pores with the pore diameter of 2-100 nm in the total pore volume of 20-38%, preferably 25-35%, the unit cell constant of 2.440-2.455 nm, preferably 2.442-2.453 nm, and the framework silicon-aluminum ratio (SiO 2.440-2.455 nm, preferably 2.442-2.453 nm)₂/Al₂O₃Molar ratio) is: 7 to 14 is, for example, 7.8 to 12.6, the percentage of non-framework aluminum content in the molecular sieve to the total aluminum content is not higher than 10%, preferably 3 to 9, the relative crystallinity is not lower than 70%, preferably not lower than 71%, the lattice collapse temperature is preferably 1065 to 1080 ℃, and the ratio of the amount of B acid to the amount of L acid in the total acid amount of the modified Y-type molecular sieve measured at 200 ℃ by a pyridine adsorption infrared method is not lower than 3.50, for example, 3.6 to 4.6.

In the catalytic cracking catalyst provided by the invention, the modified Y-type molecular sieve is a rare earth-containing ultrastable Y molecular sieve rich in secondary pores, the secondary pore distribution curve with the pore diameter of 2 nm-100 nm in the molecular sieve is in double-variable pore distribution, wherein the most variable pore diameter of the secondary pores with smaller pore diameters is 2 nm-5 nm, and the most variable pore diameter of the secondary pores with larger pore diameters is 8 nm-20 nm, preferably 8 nm-18 nm. Preferably, the pore diameter is 8nm to 1The proportion of the secondary pores of 00nm to the total secondary pores (2nm to 100nm) is 40% to 80%, preferably 45% to 77%, for example, 45% to 55% or 55% to 77%. SiO of the molecular sieve₂/Al₂O₃7 to 14, preferably 7.8 to 13, and a unit cell constant of 2.440 to 2.455nm, preferably 2.442 to 2.453 nm.

The preparation process of the modified Y-type molecular sieve comprises the step of contacting the Y-type molecular sieve with silicon tetrachloride to carry out dealuminization and silicon supplementation reaction.

In the preparation method of the catalytic cracking catalyst, the NaY molecular sieve and the rare earth solution are subjected to ion exchange reaction in the step (1) to obtain the Y-type molecular sieve with the content of sodium oxide reduced and the conventional unit cell size of rare earth. The NaY molecular sieve can be purchased commercially or prepared according to the existing method, and in one embodiment, the unit cell constant of the NaY molecular sieve is 2.465-2.472 nm, and the framework silicon-aluminum ratio (SiO)₂/Al₂O₃Molar ratio) of 4.5 to 5.2, a relative crystallinity of 85% or more, for example, 85 to 95%, and a sodium oxide content of 13.0 to 13.8% by weight. The NaY molecular sieve and the rare earth solution are subjected to ion exchange reaction, the exchange temperature is preferably 15-95 ℃, such as 20-65 ℃ or 65-95 ℃, and the exchange time is preferably 30-120 minutes, such as 45-90 minutes. NaY molecular sieve (dry basis) rare earth salt (RE)₂O₃Meter) H₂O is 1:0.01 to 0.18:5 to 20 by weight. In one embodiment, the ion exchange reaction of the NaY molecular sieve and the rare earth solution comprises the following steps of mixing the NaY molecular sieve, rare earth salt and H₂The exchange between rare earth ions and sodium ions is carried out by stirring a mixture of NaY molecular sieve (also called NaY zeolite), rare earth salt and water at a weight ratio of 1: 0.01-0.18: 5-15 at 15-95 ℃, for example, room temperature to 60 ℃, or 20-60 ℃, or 30-45 ℃, or 65-95 ℃, preferably for 30-120 minutes. In one embodiment, the weight ratio of NaY molecular sieve to water is: 1: 6-20, preferably: 7-15. Mixing NaY molecular sieve, rare earth salt and water to form a mixture, forming slurry by mixing NaY molecular sieve and water, and adding aqueous solution of rare earth salt and/or rare earth salt into the slurryThe soil solution is a solution of rare earth salt, and the rare earth salt is preferably rare earth chloride and/or rare earth nitrate. The rare earth such as one or more of La, Ce, Pr, Nd and misch metal, preferably, the misch metal contains one or more of La, Ce, Pr and Nd, or further contains at least one of rare earth other than La, Ce, Pr and Nd. The washing in step (1) is intended to wash out exchanged sodium ions, and for example, deionized water or decationized water may be used for washing. Preferably, the rare earth content of the rare earth-containing Y-type molecular sieve with the reduced sodium oxide content obtained in step (1) and the conventional unit cell size is calculated as RE₂O₃5.5 to 14 wt%, for example 7 to 14 wt% or 7.5 to 13 wt%, sodium oxide content of not more than 9 wt%, for example 5.5 to 8.5 wt% or 5.5 to 7.5 wt%, and unit cell constant of 2.465nm to 2.472 nm.

In the preparation method of the modified Y-type molecular sieve, the Y-type molecular sieve with the conventional unit cell size containing rare earth is roasted for 4.5-7 hours at the temperature of 350-520 ℃, such as 350-480 ℃ and in the atmosphere of 30-95 vol% of water vapor in step (2), preferably, the roasting temperature in step (2) is 380-500 ℃, such as 380-480 ℃, the roasting atmosphere is 40-80 vol% or 70-95 vol% of water vapor, and the roasting time is 5-6 hours. The water vapor atmosphere contains 30-95 vol% of water vapor and other gases such as one or more of air, helium or nitrogen. The Y-type molecular sieve with the reduced unit cell constant in the step (2) has the unit cell constant of 2.450 nm-2.462 nm. Preferably, the calcined molecular sieve is also dried in step (2) so that the water content in the Y-type molecular sieve having a reduced unit cell constant is preferably not more than 1 wt%. The solid content of the Y-type molecular sieve sample with reduced unit cell constant obtained in the step (2) is preferably not less than 99% by weight.

In the preparation method of the catalytic cracking catalyst, the SiCl is added in the step (3)₄: the weight ratio of the Y-type zeolite (on a dry basis) is preferably 0.3-0.6: 1, the reaction temperature is preferably 350-500 ℃, and the step (3) can be washed or notWashing, which may or may not be dried after washing, may be carried out by a conventional washing method, and may be washed with water such as decationized water or deionized water in order to remove Na remaining in the zeolite⁺，Cl^-And Al³⁺Etc. soluble by-products, for example the washing conditions may be: the weight ratio of the washing water to the molecular sieve can be 5-20: 1, molecular sieve: h₂The weight ratio of O is 1: 6-15, the pH value is preferably 2.5-5.0, and the washing temperature is 30-60 ℃. Usually, the washing is carried out in such a manner that no free Na is detected in the washing solution after washing⁺，Cl^-And Al³⁺Plasma, usually Na in washed molecular sieve samples⁺，Cl^-And Al³⁺The respective contents of ions do not exceed 0.05 wt.%.

In the preparation method of the catalytic cracking catalyst, in the step (4), the gas-phase ultrastable modified Y-type molecular sieve obtained in the step (3) is contacted with an acid solution to react (the method is called as channel cleaning modification, which is called as channel cleaning for short, or called as acid treatment modification). In one embodiment, the gas phase ultrastable modified Y-type molecular sieve obtained in step (3) is contacted with an acid solution for reaction, the gas phase ultrastable modified molecular sieve, that is, the gas phase ultrastable modified Y-type molecular sieve, is mixed with the acid solution, and reacted for a period of time, and then the reacted molecular sieve is separated from the acid solution, for example, by filtration, and then optionally washed and optionally dried to obtain the modified Y-type molecular sieve provided by the present invention, wherein the purpose of washing is to remove Na remaining in the zeolite⁺，Cl^-And Al³⁺Etc. soluble by-products, for example the washing conditions may be: the weight ratio of the washing water to the molecular sieve can be 5-20: 1, typically molecular sieve: h₂The weight ratio of O is 1: 6-15, the pH value is preferably 2.5-5.0, and the washing temperature is 30-60 ℃. And (3) contacting the gas-phase ultra-stable modified Y-shaped molecular sieve obtained in the step (3) with an acid solution, wherein the weight ratio of the acid to the molecular sieve (calculated on a dry basis) is 0.001-0.15: 1 is, for example, 0.002 to 0.1: 1 or 0.01 to 0.05: 1, the weight ratio of water to the molecular sieve calculated on a dry basis is 5-20: 1 is, for example, 8 to 15: 1, temperature at which the contact is carried outThe temperature is 60 to 100 ℃, for example 80 to 99 ℃, preferably 88 to 98 ℃.

Preferably, the acid in the acid solution (aqueous acid solution) is at least one organic acid and at least one inorganic acid of medium or higher strength. The organic acid can be one or more of oxalic acid, malonic acid, succinic acid (succinic acid), methylsuccinic acid, malic acid, tartaric acid, citric acid and salicylic acid, and the inorganic acid with medium strength or higher can be one or more of phosphoric acid, hydrochloric acid, nitric acid and sulfuric acid. The contact temperature is preferably 80-99 ℃, for example 85-98 ℃, and the contact time is more than 60 minutes, for example 60-240 minutes or 90-180 minutes. The weight ratio of the organic acid to the molecular sieve is 0.01-0.10: 1 is, for example, 0.02 to 0.05: 1 or 0.03 to 0.1: 1, the weight ratio of the inorganic acid with the medium strength or more to the molecular sieve is 0.01-0.05: 1 is, for example, 0.02 to 0.05: 1, the weight ratio of water to the molecular sieve is preferably 5-20: 1 is, for example, 8 to 15: 1.

preferably, the pore cleaning modification is carried out in two steps, and firstly, inorganic acid with the strength higher than medium is contacted with the molecular sieve, wherein the weight ratio of the inorganic acid with the strength higher than medium to the molecular sieve is 0.01-0.05: 1 is, for example, 0.02 to 0.05: 1, the weight ratio of water to the molecular sieve is preferably 5-20: 1 is, for example, 8 to 15: 1, the temperature of the contact reaction is 80-99 ℃, preferably 90-98 ℃, and the reaction time is 60-120 minutes; and then contacting the treated molecular sieve with organic acid, wherein the weight ratio of the organic acid to the molecular sieve is (0.02-0.10): 1 is, for example, 0.02 to 0.10: 1 or 0.05-0.08: 1, the weight ratio of water to the molecular sieve is preferably 5-20: 1 is, for example, 8 to 15: 1, the temperature of the contact reaction is 80-99 ℃, preferably 90-98 ℃, and the reaction time is 60-120 minutes. Wherein in the weight ratio, the molecular sieve is on a dry basis.

The preparation method of the catalytic cracking catalyst provided by the invention comprises the steps of forming a slurry by raw materials comprising the modified Y-shaped molecular sieve, clay and alumina binder and water, and spray drying, wherein in one embodiment, the preparation method of the modified Y-shaped molecular sieve comprises the following steps:

(1) carrying out ion exchange reaction on a NaY molecular sieve (also called NaY zeolite) and a rare earth solution, filtering and washing to obtain a Y-type molecular sieve containing rare earth and having a conventional unit cell size and reduced sodium oxide content; the ion exchange is carried out for 30-120 minutes under the conditions of stirring and the temperature of 15-95 ℃, preferably 65-95 ℃;

(2) roasting the rare earth-containing Y-type molecular sieve with the normal unit cell size and the reduced sodium oxide content for 4.5-7 hours at the temperature of 350-480 ℃ in the atmosphere containing 30-90 vol% of water vapor, and drying to obtain the Y-type molecular sieve with the reduced unit cell constant and the water content of less than 1 wt%; the unit cell constant of the Y-type molecular sieve with the reduced unit cell constant is 2.450 nm-2.462 nm;

(3) mixing said reduced unit cell constant Y-type molecular sieve sample having a water content of less than 1 wt% with heat vaporized SiCl₄Gas contact of SiCl₄: the weight ratio of the Y-type molecular sieve with the water content lower than 1 wt% and the reduced unit cell constant (calculated by dry basis) is 0.1-0.7: 1, carrying out contact reaction for 10 minutes to 5 hours at the temperature of 200-650 ℃, optionally washing and optionally filtering to obtain a gas-phase ultra-stable modified Y-type molecular sieve;

(4) and (4) contacting the gas-phase superstable modified Y-shaped molecular sieve obtained in the step (3) with an acid solution for acid treatment modification. Mixing the modified Y-type molecular sieve subjected to gas phase ultra-stable treatment in the step (3) with inorganic acid with medium strength and water, contacting at 80-99 ℃, preferably 90-98 ℃, for at least 30 minutes, such as 60-120 minutes, then adding organic acid, contacting at 80-99 ℃, preferably 90-98 ℃, for at least 30 minutes, such as 60-120 minutes, filtering, optionally washing and optionally drying to obtain the modified Y-type molecular sieve provided by the invention; wherein the preferable weight ratio of the organic acid to the molecular sieve on a dry basis is 0.02-0.10: 1, the weight ratio of the inorganic acid with the medium strength or more to the molecular sieve based on a dry basis is 0.01-0.06: 1, the weight ratio of water to the molecular sieve is 5-20: 1.

the following examples further illustrate the invention but are not intended to limit the invention thereto.

In the examples and comparative examples, the NaY molecular sieve (also known as NaY zeolite) isProvided by Qilu division of China petrochemical catalyst, the sodium oxide content is 13.5 wt%, and the framework silicon-aluminum ratio (SiO)₂/Al₂O₃Molar ratio) of 4.6, relative crystallinity of 90%; the chlorinated rare earth and the nitric acid rare earth are chemical pure reagents produced by Beijing chemical plants. The pseudoboehmite is an industrial product produced by Shandong aluminum factories, and has the solid content of 61 percent by weight; the kaolin is kaolin specially used for a cracking catalyst produced by Suzhou China kaolin company, and has the solid content of 76 weight percent; the alumina sol was provided by the Qilu division of China petrochemical catalyst, Inc., in which the alumina content was 21% by weight.

The analysis method comprises the following steps: in each comparative example and example, the elemental content of the zeolite was determined by X-ray fluorescence spectroscopy; the unit cell constants and relative crystallinity of the zeolite were measured by X-ray powder diffraction (XRD) using RIPP 145-90 and RIPP146-90 standard methods (compiled by petrochemical analysis method (RIPP test method), Yankee et al, scientific Press, published in 1990), and the framework silica-alumina ratio of the zeolite was calculated from the following formula: SiO 2₂/Al₂O₃＝(2.5858-a₀) X 2/(a0-2.4191) wherein a₀Is the unit cell constant in nm; the total silicon-aluminum ratio of the zeolite is calculated according to the content of Si and Al elements measured by an X-ray fluorescence spectrometry, and the ratio of the framework Al to the total Al can be calculated by the framework silicon-aluminum ratio measured by an XRD method and the total silicon-aluminum ratio measured by an XRF method, so that the ratio of non-framework Al to the total Al can be calculated. The crystal structure collapse temperature was determined by Differential Thermal Analysis (DTA).

In each comparative example and example, the acid center type of the molecular sieve and its acid amount were determined by infrared analysis using pyridine adsorption. An experimental instrument: model Bruker IFS113V FT-IR (fourier transform infrared) spectrometer, usa. An experimental method for measuring the amount of B acid and the amount of L acid in total acid at 200 ℃ by using a pyridine adsorption infrared method comprises the following steps: and (3) carrying out self-supporting tabletting on the sample, and placing the sample in an in-situ cell of an infrared spectrometer for sealing. Heating to 400 deg.C, and vacuumizing to 10 deg.C^-3And Pa, keeping the temperature for 2h, and removing gas molecules adsorbed by the sample. The temperature is reduced to room temperature, pyridine vapor with the pressure of 2.67Pa is introduced to keep the adsorption equilibrium for 30 min. Then heating to 200 ℃, and vacuumizing to 10 DEG C^-3Desorbing at Pa for 30min, cooling to room temperature, performing spectrograph, and sweepingThe number range of the drawing waves: 1400cm^-1～1700cm^-1And obtaining the pyridine absorption infrared spectrogram of the sample desorbed at 200 ℃. According to pyridine absorption infrared spectrogram of 1540cm^-1And 1450cm^-1The strength of the adsorption peak is characterized to obtain the total content in the molecular sieve

Relative amount of acid center (B acid center) to Lewis acid center (L acid center).

In each of the comparative examples and examples, the secondary pore volume was determined as follows: measuring total pore volume of the molecular sieve according to adsorption isotherm, measuring micropore volume of the molecular sieve according to T mapping method from adsorption isotherm, subtracting micropore volume from total pore volume to obtain secondary pore volume,

the chemical reagents used in the comparative examples and examples are not specifically noted, and are specified to be chemically pure.

Example 1

2000Kg (dry basis) of SiO skeleton₂/Al₂O₃4.6 NaY zeolite (sodium oxide content 13.5 wt%, available from the Kikukushi company, China petrochemical catalyst, Qilu division) was charged in a vessel containing 20m³Stirring the mixture evenly at 25 ℃ in a primary exchange tank of water, and then adding 600L of RECl₃Solutions (RECl)₃Rare earth concentration in solution as RE₂O₃319g/L), continuously stirring for 60 minutes, filtering, washing, and sending a filter cake into a flash evaporation drying furnace for drying; obtaining the rare earth-containing Y-type molecular sieve with the normal unit cell size and the reduced sodium oxide content, wherein the sodium oxide content is 7.0 weight percent, and the unit cell constant is 2.471 nm; then, the mixture was sent to a roasting furnace and roasted at 390 ℃ for 6 hours in 50% steam (50% by volume of steam in the atmosphere); then, roasting for 2.5 hours at 500 ℃ in a dry air atmosphere (water vapor content is less than 1 volume percent) to make the water content less than 1 weight percent, so as to obtain the Y-type molecular sieve with reduced unit cell constant, wherein the unit cell constant is 2.455 nm; then, directly reducing the unit cell constant of the Y-type molecular sieve materialSending the mixture into a continuous gas phase ultra-stable reactor to carry out gas phase ultra-stable reaction. The gas phase hyperstable reaction process of the molecular sieve in the continuous gas phase hyperstable reactor and the subsequent tail gas absorption process are carried out according to the method disclosed in embodiment 1 of the CN103787352A patent, and the process conditions are that SiCl is adopted₄: weight ratio of Y-type zeolite 0.5: 1, the feed rate of the molecular sieve is 800 kg/h, and the reaction temperature is 400 ℃. Separating the molecular sieve material after gas phase superstable reaction by a gas-solid separator, and feeding into a secondary exchange tank, wherein 20m is added in advance in the secondary exchange tank³The water (2) was added to the molecular sieve material in the secondary exchange tank in an amount of 2000Kg (dry basis) by weight, stirred well, and then 0.6m hydrochloric acid having a concentration of 10% by weight was slowly added³Heating to 90 ℃, stirring for 60 minutes, then adding 140Kg of citric acid, continuing stirring for 60 minutes at 90 ℃, filtering, washing and drying to obtain a modified Y-type molecular sieve (molecular sieve is also called zeolite) product, and marking as SZ-1. Table 1 shows the composition of SZ-1, the unit cell constant, the relative crystallinity, the framework Si/Al ratio, the structural collapse temperature, the specific surface area, the percentage of the secondary pores with larger pore diameter (8 nm-100 nm) in the total secondary pores (2-100 nm), and the total secondary pore volume.

After SZ-1 is aged for 17 hours in a naked state at 800 ℃ in a 100% water vapor atmosphere, the relative crystallinity of the molecular sieve before and after the SZ-1 is aged is analyzed by an XRD method, and the relative crystallinity retention after the aging is calculated, and the result is shown in Table 2, wherein:

1572 g of pseudo-boehmite containing 61 wt% of alumina was added to 7818 g of decationized water, 195ml of chemically pure hydrochloric acid (containing 36 wt% of HCl) was added under stirring, and aged at 70 ℃ for 1 hour, then 165ml of phosphoric acid (85% concentration, analytical purity, produced by beijing chemical plant) and 390 g of magnesium chloride hexahydrate (204 g of magnesium chloride hexahydrate, produced by beijing bicycular reagent plant) aqueous solution were added and slurried to obtain a slurry of alumina containing an additive.

5715 g of an aluminium sol having an alumina content of 21% by weight are added15642 g of decationized water, 7302 g of kaolin having a solids content of 76% by weight was added with stirring and slurried for 60 minutes to obtain a kaolin slurry. 3839 g of pseudo-boehmite having an alumina content of 61% by weight was added to 9381 g of decationized water, slurried, 231ml of chemically pure hydrochloric acid (containing 36% by weight of HCl) was added thereto under stirring, the prepared kaolin slurry was added after aging for 60 minutes, the prepared alumina slurry containing an additive was added, slurried, and then, 4200 g (dry basis) of SZ-1 molecular sieve and REY molecular sieve (produced by the Zilu division, China petrochemical catalyst Co., Ltd.) were added, the rare earth content (in terms of RE) was added₂O₃Calculated) 18 wt%, silicon to aluminum ratio (SiO)₂/Al₂O₃Molar ratio 4.6)]750 g (dry basis), pulping, spray-drying at an inlet temperature of 650 ℃ and a tail gas temperature of 180 ℃, washing with deionized water, and drying to obtain the catalyst, which is marked as SC-1.

Example 2

2000Kg (dry basis) of SiO skeleton₂/Al₂O₃4.6 NaY zeolite (sodium oxide content 13.5 wt%, available from the Kikukushi company, China petrochemical catalyst, Qilu division) was charged in a vessel containing 20m³In a first exchange tank for removing the cationic water, stirring uniformly at 90 ℃, and then adding 800L RECl₃Solutions (RECl)₃Rare earth concentration in solution as RE₂O₃319g/L) is counted, and stirring is carried out for 60 minutes; filtering, washing, and drying the filter cake in a flash evaporation drying furnace to obtain the rare earth-containing Y-type molecular sieve with the normal unit cell size, the sodium oxide content of which is reduced by 5.5 weight percent and the unit cell constant of which is 2.471nm, and then, feeding the rare earth-containing Y-type molecular sieve into a roasting furnace to roast for 5.5 hours at the temperature (atmosphere temperature) of 450 ℃ and in the atmosphere of 80 percent of water vapor; then, the molecular sieve material enters a roasting furnace for roasting and drying treatment, the roasting temperature is 500 ℃, the atmosphere is a dry air atmosphere, the roasting time is 2 hours, the water content is lower than 1 weight percent, and the Y-type molecular sieve with the reduced unit cell constant is obtained, and the unit cell constant is 2.461 nm; then, the Y-shaped molecular sieve material with the reduced unit cell constant is directly sent into a continuous gas-phase ultra-stable reactor for gas-phase ultra-stable reaction. Gas phase ultra-stable reaction process of molecular sieve in continuous gas phase ultra-stable reactorThe process and the subsequent tail gas absorption process are carried out according to the method disclosed in the CN103787352A patent in the embodiment 1, and the process conditions are as follows: SiCl₄: weight ratio of Y-type zeolite 0.25: 1, the feed rate of the molecular sieve was 800 kg/hour, and the reaction temperature was 490 ℃. Separating the molecular sieve material after gas phase superstable reaction by a gas-solid separator, and feeding into a secondary exchange tank, wherein 20m is added in advance in the secondary exchange tank³Adding the decationized water into a molecular sieve material in a secondary exchange tank, wherein the weight of the molecular sieve material is 2000Kg (dry basis), uniformly stirring, and slowly adding a sulfuric acid solution with the concentration of 7 weight percent, and the concentration of the sulfuric acid solution is 0.9m³And heating to 93 ℃, stirring for 80 minutes, then adding 70Kg of citric acid and 50Kg of tartaric acid, continuing stirring for 70 minutes at 93 ℃, filtering, washing and drying to obtain a modified Y-type molecular sieve product, and marking as SZ-2. Table 1 shows the composition of SZ-2, the percentage of the total secondary pores (2-100 nm) occupied by the unit cell constant, the relative crystallinity, the framework Si/Al ratio, the structural collapse temperature, the specific surface area and the secondary pores with larger pore diameter (8-100 nm), and the total secondary pore volume.

After SZ-2 is aged at 800 ℃ for 17 hours under 100% of water vapor in a naked state (the aging of the zeolite under 100% of water vapor for 17 hours under 100% of water vapor), the crystallinity of the zeolite before and after the aging of the SZ-2 is analyzed by an XRD method, and the relative crystal retention after the aging is calculated, and the results are shown in Table 2.

1476 grams of pseudoboehmite containing 61% by weight of alumina was added to 7344 grams of decationized water, 185ml of chemically pure hydrochloric acid (containing 36% by weight of HCl) was added with stirring, followed by aging at 70 ℃ for 1 hour, and then 1080 grams of magnesium chloride hexahydrate (617 grams of magnesium chloride hexahydrate, analytical pure), aqueous solution (produced by beijing bicycnic reagent factory) was added and slurried to obtain a slurry of alumina containing additives.

4284 g of alumina sol with the alumina content of 21 weight percent is added into 3753 g of decationized water, 6908 g of kaolin with the solid content of 76 weight percent is added under stirring, and the mixture is pulped for 60 minutes to obtain kaolin slurry. 4423 g of pseudo-boehmite containing 61 wt% of alumina was added to 22037 g of decationized water, 482ml of hydrochloric acid (chemical purity, concentration 36 wt%) was added under stirring, the resulting kaolin slurry was aged for 60 minutes, and then the slurry was added and slurried, and the slurry of the additive-containing alumina was added and slurried, and then 4950 g (dry basis) of SZ-2 molecular sieve was added, and then the slurry was slurried, and spray-dried and washed (same as in example 1), and dried to obtain catalyst SC-2.

Example 3

2000Kg (dry basis) of SiO skeleton₂/Al₂O₃4.6 NaY zeolite (sodium oxide content 13.5 wt%, available from the Kikukushi company, China petrochemical catalyst, Qilu division) was charged in a vessel containing 20m³Stirring in a first exchange tank for removing cationic water at 95 deg.C, and adding 570L RECl₃Solutions (RECl)₃Rare earth concentration in solution as RE₂O₃319g/L), continuously stirring for 60 minutes, filtering, washing, continuously feeding a filter cake into a flash drying furnace for drying to obtain the Y-type molecular sieve with the normal unit cell size and the reduced sodium oxide content, wherein the sodium oxide content is 7.5 weight percent, and the unit cell constant is 2.471 nm; then, the mixture is sent into a roasting furnace to be roasted for 5 hours at the roasting temperature of 470 ℃ under the atmosphere containing 70 volume percent of water vapor; then, the molecular sieve material enters a roasting furnace to be roasted and dried, wherein the roasting temperature is 500 ℃, the roasting atmosphere is a dry air atmosphere, the roasting time is 1.5 hours, the water content is lower than 1 weight percent, and the Y-type molecular sieve with the reduced unit cell constant is obtained, and the unit cell constant is 2.458 nm; then, the Y-shaped molecular sieve material with the reduced unit cell constant is sent into a continuous gas-phase ultra-stable reactor to carry out gas-phase ultra-stable reaction. The gas phase hyperstable reaction process of the molecular sieve in the continuous gas phase hyperstable reactor and the subsequent tail gas absorption process are carried out according to the method disclosed in embodiment 1 of the CN103787352A patent, and the process conditions are as follows: SiCl₄: weight ratio of Y-type zeolite 0.45: 1, the feed rate of the molecular sieve is 800 kg/h, and the reaction temperature is 400 ℃. Separating the molecular sieve material after gas phase superstable reaction by a gas-solid separator, and feeding into a secondary exchange tank, wherein 20m is added in advance in the secondary exchange tank³Adding the decationized water into a molecular sieve material in a secondary exchange tank, wherein the weight of the molecular sieve material is 2000Kg (dry basis), uniformly stirring, and slowly adding 5 weight percent of nitric acid 1.2m³And heating to 95 deg.C, and continuingStirring for 90 minutes, then adding 90Kg of citric acid and 40Kg of oxalic acid, stirring for 70 minutes at 93 ℃, filtering, washing, sampling and drying, and recording the sample as SZ-3. Table 1 shows the composition of SZ-3, the percentage of the total secondary pores (2-100 nm) occupied by the unit cell constant, the relative crystallinity, the framework Si/Al ratio, the structural collapse temperature, the specific surface area and the secondary pores with larger pore diameter (80-100 nm), and the total secondary pore volume. After aging SZ-3 in a naked state at 800 ℃ for 17 hours by 100% steam, the crystallinity of the zeolite before and after aging of SZ-3 is analyzed by an XRD method and the relative crystal retention after aging is calculated, and the result is shown in Table 2.

1968 g of pseudo-boehmite having an alumina content of 61% by weight was added to 9792 g of decationized water, 246ml of chemically pure hydrochloric acid (HCl content of 36% by weight) was added under stirring, and the mixture was aged at 70 ℃ for 1 hour, after which 588ml of phosphoric acid (85% strength, analytical purity, manufactured by Beijing chemical plant) was added and slurried to obtain a slurry of alumina containing an additive.

5712 g of an alumina sol having an alumina content of 21 wt.% was added to 9405 g of decationized water, 12684 g of kaolin having a solid content of 76 wt.% was added under stirring, and the mixture was pulped for 60 minutes to obtain kaolin slurry. Adding 7866 g of pseudo-boehmite containing 61 wt% of alumina into 25458 g of decationized water, adding 852ml of chemically pure hydrochloric acid (concentration: 36 wt%) under stirring, aging for 60 min, adding the prepared kaolin slurry, pulping, adding the prepared alumina slurry containing additive, pulping, adding 5820 g (dry basis) of SZ-3 molecular sieve, REY molecular sieve (produced by Qilu division of China petrochemical catalyst Co., Ltd.), and rare earth (in RE)₂O₃Calculated) 18 wt%, silicon to aluminum ratio (SiO)₂/Al₂O₃Molar ratio 4.6)]1863 g (dry basis) and ZRP-5 molecular sieve (produced by ZRP-5 molecular sieve of Qilu Branch of China petrochemical catalyst Co., Ltd., rare earth content of 0.5 wt%, Si/Al ratio of 45)1164 g (dry basis), pulping, spray drying and washing (same as example 1), and drying to obtain the catalyst, which is marked as SC-3.

Comparative example 1

2000 g of NaY molecular sieve (dry basis) was added to 20 l of decationized ionStirring the mixture in the aqueous solution to mix the mixture evenly, and adding 1000 g (NH)₄)₂SO₄Stirring, heating to 90-95 deg.C, holding for 1 hr, filtering, washing, drying at 120 deg.C, performing hydrothermal modification treatment (at 650 deg.C, roasting with 100% water vapor for 5 hr), adding into 20L of decationized water solution, stirring, mixing, adding 1000 g (NH)₄)₂SO₄Stirring, heating to 90-95 ℃, keeping for 1 hour, filtering, washing, drying a filter cake at 120 ℃, and then performing second hydrothermal modification treatment (roasting at 650 ℃ under 100% of water vapor for 5 hours) to obtain the rare earth-free hydrothermal ultrastable Y-shaped molecular sieve which is subjected to twice ion exchange and twice hydrothermal ultrastable and is marked as DZ 1. Table 1 shows the composition of DZ-1, the percentage of the total secondary pores (2-100 nm) occupied by the unit cell constant, the relative crystallinity, the framework Si/Al ratio, the structural collapse temperature, the specific surface area, and the secondary pores with larger pore diameters (8-100 nm), and the total secondary pore volume. After aging DZ-1 in the bare state at 800 ℃ for 17 hours with 100% steam, the crystallinity of the zeolite before and after aging DZ-1 was analyzed by XRD and the relative crystal retention after aging was calculated, the results are shown in Table 2.

714.5 g of an alumina sol having an alumina content of 21% by weight were added to 1565.5 g of decationized water, stirring was started, and 2763 g of kaolin having a solids content of 76% by weight were added and dispersed for 60 minutes. 2049 g of pseudo-boehmite with the alumina content of 61 wt% is taken and added into 8146 g of decationized water, 210ml of hydrochloric acid with the concentration of 36% is added under the stirring state, dispersed kaolin slurry is added after acidification is carried out for 60 minutes, then 1500 g (dry basis) of finely ground DZ-1 molecular sieve is added, after even stirring, spray drying and washing treatment are carried out, and the catalyst is obtained after drying and is marked as DC-1. Wherein the obtained DC-1 catalyst contains 30 wt% of DZ-1 molecular sieve, 42 wt% of kaolin, 25 wt% of pseudo-boehmite and 3 wt% of alumina sol.

Comparative example 2

2000 g of NaY molecular sieve (dry basis) is added into 20L of decationized aqueous solution, stirred to be uniformly mixed, and 1000 g of (NH) is added₄)₂SO₄Stirring, heating to 90-95 deg.C and keeping at 1And h, filtering, washing, drying a filter cake at 120 ℃, and then performing hydrothermal modification treatment, wherein the hydrothermal modification treatment comprises the following steps: roasting at 650 deg.C under 100% steam for 5 hr, adding into 20L decationized water solution, stirring, mixing, adding 200ml RE (NO)₃)₃Solutions (with RE)₂O₃The concentration of the rare earth solution is measured as follows: 319g/L) and 900 g (NH)₄)₂SO₄Stirring, heating to 90-95 ℃, keeping for 1 hour, then filtering, washing, drying a filter cake at 120 ℃, and then carrying out second hydrothermal modification treatment (roasting at 650 ℃ under 100% of water vapor for 5 hours) to obtain the rare earth-containing hydrothermal ultrastable Y-type molecular sieve which is subjected to twice ion exchange and twice hydrothermal ultrastable, and is marked as DZ-2. Table 1 shows the composition of DZ-2, the percentage of the total secondary pores (2-100 nm) occupied by the unit cell constant, the relative crystallinity, the framework Si/Al ratio, the structural collapse temperature, the specific surface area, and the secondary pores with larger pore diameters (8-100 nm), and the total secondary pore volume. After aging DZ-2 in the bare state with 100% steam at 800 ℃ for 17 hours, the crystallinity of the zeolite before and after aging DZ-2 was analyzed by XRD and the relative crystal retention after aging was calculated, the results are shown in Table 2.

DZ-2 molecular sieve, kaolin, water, pseudo-boehmite binder and alumina sol are formed into slurry according to a conventional preparation method of a catalytic cracking catalyst, the slurry is spray-dried to prepare a microspherical catalyst, and the prepared catalytic cracking catalyst is marked as DC-2 (refer to the preparation method of comparative example 1). Wherein the obtained DC-2 catalyst contains 30 wt% of DZ-2 molecular sieve, 42 wt% of kaolin, 25 wt% of pseudo-boehmite and 3 wt% of alumina sol on a dry basis.

Comparative example 3

2000kg of NaY molecular sieve (dry basis) was added to 20m³Stirring in water to mix well, adding 650L RE (NO)₃)₃Stirring the solution (319g/L), heating to 90-95 ℃ for 1 hour, filtering, washing, continuously feeding the filter cake into a flash evaporation and roasting furnace for roasting and drying, controlling the roasting temperature to be 500 ℃, controlling the roasting atmosphere to be a dry air atmosphere, roasting for 2 hours to ensure that the water content is lower than 1 weight percent, and drying the dried molecular sieveThe materials are sent into a continuous gas phase ultra-stable reactor to carry out gas phase ultra-stable reaction. The gas phase hyperstable reaction process of the molecular sieve in the continuous gas phase hyperstable reactor and the subsequent tail gas absorption process are carried out according to the method disclosed in embodiment 1 of the CN103787352A patent, and the process conditions are as follows: SiCl₄: weight ratio of Y-type zeolite 0.4: 1, the feed rate of the molecular sieve is 800 kg/h, and the reaction temperature is 580 ℃. Separating the molecular sieve material after gas phase superstable reaction by a gas-solid separator, and feeding into a secondary exchange tank, wherein 20m is added in advance in the secondary exchange tank³The water (2) is added into a molecular sieve material in a secondary exchange tank, the weight of the molecular sieve material is 2000Kg (dry basis), the mixture is stirred evenly, and then 5 weight percent of nitric acid with the weight of 1.2m is slowly added³And the temperature is raised to 95 ℃, the stirring is continued for 90 minutes, then 90Kg of citric acid and 40Kg of oxalic acid are added, the stirring is continued for 70 minutes at 93 ℃, then the filtration, the washing, the sampling and the drying are carried out, and the sample is recorded as DZ-3. Table 1 shows the composition of DZ-3, the percentage of the total secondary pores (2-100 nm) occupied by the unit cell constant, the relative crystallinity, the framework Si/Al ratio, the structural collapse temperature, the specific surface area, and the secondary pores with larger pore diameters (8-100 nm), and the total secondary pore volume. After aging DZ-3 in the bare state at 800 ℃ for 17 hours with 100% steam, the crystallinity of the zeolite before and after aging DZ-3 was analyzed by XRD and the relative crystal retention after aging was calculated, the results are shown in Table 2.

DZ-3 molecular sieve, kaolin, water, pseudo-boehmite binder and alumina sol are formed into slurry according to a conventional preparation method of a catalytic cracking catalyst, the slurry is spray-dried to prepare a microspherical catalyst, and the prepared catalytic cracking catalyst is marked as DC-3 (refer to the preparation method of comparative example 1). Wherein, the obtained DC-3 catalyst contains 30 weight percent of DZ-3 molecular sieve, 42 weight percent of kaolin, 25 weight percent of pseudo-boehmite and 3 weight percent of alumina sol.

Comparative example 4

Catalyst DC-4 was prepared according to the procedure of example 2, except that molecular sieve SZ-2 was replaced with molecular sieve DZ-3 prepared in comparative example 3.

The light oil micro-reactivity evaluation was performed on the catalytic cracking catalysts prepared in examples 1 to 3 and comparative examples 1 to 4. Evaluation of light oil microreflection: the light oil microreflection activity of the samples was evaluated by the standard method of RIPP92-90 (compiled by "petrochemical analysis method" (RIPP test method) Yangcui et al, published by scientific publishing Co., Ltd. 1990), the catalyst loading was 5.0g, the reaction temperature was 460 ℃, the raw oil was Hongkong light diesel oil with distillation range of 235-.

Light oil Microreactivity (MA) (gasoline production at less than 216 ℃ in product + gas production + coke production)/total feed amount × 100%

The main properties of the catalytic cracking catalysts prepared in examples 1 to 3 and comparative examples 1 to 4 are shown in Table 3.

Examples 4 to 6

The heavy oil cracking performance of the catalytic cracking catalysts prepared in examples 1 to 3 was evaluated, and the results are shown in table 5.

Evaluation conditions for cracking performance of heavy oil: the catalyst was first aged at 800 ℃ for 17 hours in a 100% steam atmosphere, and then evaluated on an ACE (fixed fluidized bed) apparatus, with the raw oil as vigorously mixed tris-2007 (properties are shown in table 4), and the reaction temperature was 500 ℃.

Wherein, the conversion rate is gasoline yield, liquefied gas yield, dry gas yield and coke yield

Yield of light oil is gasoline yield and diesel oil yield

Liquid yield is liquefied gas, gasoline and diesel oil

Coke selectivity-coke yield/conversion

Comparative examples 5 to 8

The catalytic cracking performance of the catalytic cracking catalysts prepared in comparative examples 1 to 4 was evaluated according to the methods of examples 4 to 6, and the results are shown in table 5.

TABLE 1

As can be seen from table 1, the high-stability modified Y-type molecular sieve provided by the present invention has low sodium oxide content, low non-framework aluminum content when the silicon-aluminum ratio of the molecular sieve is high, a pore volume of secondary pores of 2.0nm to 100nm in the molecular sieve accounts for a higher percentage of the total pore volume, and B acid/L acid (the ratio of the total B acid amount to the L acid amount) is higher, and has high crystallinity, particularly higher crystallinity value when the rare earth content of the molecular sieve has a smaller unit cell constant, high lattice collapse temperature, and high thermal stability.

TABLE 2

As can be seen from table 2, after the modified Y-type molecular sieve provided by the present invention is aged under the harsh conditions of 800 ℃ and 17 hours in the exposed state of the molecular sieve sample, the sample has a higher relative crystal retention, which indicates that the modified Y-type molecular sieve provided by the present invention has a higher hydrothermal stability.

TABLE 3

TABLE 4ACE evaluation of raw oil Properties

TABLE 5

Example numbering	Example 4	Example 5	Example 6	Comparative example 5	Comparative example 6	Comparative example 7	Comparative example 8
								Sample numbering	SC-1	SC-2	SC-3	DC-1	DC-2	DC-3	DC-4
The molecular sieve used	SZ-1	SZ-2	SZ-3	DZ-1	DZ-2	DZ-3	DZ-3
								Ratio of agent to oil (weight ratio)	4	4	4	9	8	5	5
Product distribution/weight%
								Dry gas	1.04	0.98	1.01	1.55	1.48	1.47	1.45
Liquefied gas	15.41	15.81	16.09	16.86	15.33	16.31	16.32
								Coke	3.51	3.65	3.7	8.33	7.61	6.19	6.01
Gasoline (gasoline)	56.75	56.97	57.09	38.55	43.91	51.19	51.45
								Diesel oil	16.98	16.65	16.13	20.17	19.25	16.67	16.83
Heavy oil	6.31	5.94	5.98	14.54	12.42	8.17	7.94
								Total up to	100	100	100	100	100	100	100
Conversion/weight%	76.71	77.41	77.89	65.29	68.33	75.16	75.23
								Coke selectivity/weight%	4.58	4.72	4.75	12.76	11.14	8.24	7.99
Yield of light oil/weight%	73.73	73.62	73.22	58.72	63.16	67.86	68.28
								Total liquid/weight%	89.14	89.43	89.31	75.58	78.49	84.17	84.6

As can be seen from table 5, the catalytic cracking catalyst prepared by the present invention has high conversion rate, high yield of light oil and total liquid yield, and excellent coke selectivity. The modified Y-type molecular sieve provided by the invention has the advantages of high hydrothermal stability, obviously lower coke selectivity, obviously higher liquid yield, obviously higher light oil yield, higher gasoline yield and higher heavy oil conversion activity.

Claims

1. A catalytic cracking catalyst comprises 10-50 wt% of modified Y-type molecular sieve, 2-40 wt% of alumina containing an additive and 10-80 wt% of clay on a dry basis, wherein the modified Y-type molecular sieve is calculated on a dry basis; wherein, the alumina containing the additive contains 60 to 99.5 weight percent of alumina and 0.5 to 40 weight percent of additive on a dry basis, and the additive is selected from one or more compounds containing alkaline earth metal, lanthanide metal, silicon, gallium, boron or phosphorus; the modified Y-type molecular sieve has the following components, by weight, 5-12% of rare earth oxide, not more than 0.5% of sodium oxide, 0.36-0.48 mL/g of total pore volume, 20-38% of pore volume of secondary pores with the pore diameters of 2-100 nm, 2.440-2.455 nm of unit cell constant, not more than 10% of non-framework aluminum content in the modified Y-type molecular sieve, and the lattice collapse temperature of not less than 1060 ℃, and the ratio of B acid amount to L acid amount in the total acid amount of the modified Y-type molecular sieve measured at 200 ℃ by a pyridine adsorption infrared method is not less than 3.50;

the preparation method of the catalyst comprises the steps of forming a slurry containing the modified Y-type molecular sieve, alumina containing additives, clay and water, and spray drying.

2. The catalytic cracking catalyst of claim 1, wherein the modified Y-type molecular sieve has a secondary pore volume of 2nm to 100nm in pore diameter of 28% to 38% of the total pore volume.

3. The catalytic cracking catalyst of claim 1, wherein the modified Y-type molecular sieve has a secondary pore volume with a pore diameter of 80-1000 Å/a total secondary pore volume with a pore diameter of 20-1000 Å in a ratio of 40-80%.

4. The catalytic cracking catalyst of claim 1, wherein the non-framework aluminum content of the modified Y-type molecular sieve accounts for 5-9.5% of the total aluminum content, and the framework silicon-aluminum ratio is SiO₂/Al₂O₃The molar ratio is 7-14.

5. The catalytic cracking catalyst of claim 1, wherein the modified Y-type molecular sieve has a lattice collapse temperature of 1060-1085 ℃.

6. The catalytic cracking catalyst of claim 1, wherein the ratio of the amount of B acid to the amount of L acid in the total acid amount of the modified Y-type molecular sieve, measured at 200 ℃ by pyridine adsorption infrared method, is 3.5 to 6.

7. The catalytic cracking catalyst of claim 1, wherein the modified Y-type molecular sieve has a relative crystal retention of 38% or more after aging at 800 ℃ under normal pressure in a 100% steam atmosphere for 17 hours.

8. The catalytic cracking catalyst of claim 1, wherein the modified Y-type molecular sieve has a relative crystallinity of 70 to 80%.

9. The catalytic cracking catalyst according to any one of claims 1 to 8, wherein the modified Y-type molecular sieve has a rare earth oxide content of 5.5 to 10 wt%, a sodium oxide content of 0.15 to 0.3 wt%, a unit cell constant of 2.442 to 2.453nm, and a framework silica-alumina ratio of 7.8 to 12.6.

10. The catalytic cracking catalyst of claim 1, wherein the catalyst comprises 25 wt% to 40 wt% of the modified Y-type molecular sieve on a dry basis, 2 wt% to 20 wt% of the alumina containing additive on a dry basis, 5 wt% to 30 wt% of the alumina binder on a dry basis, and 30 wt% to 50 wt% of the clay on a dry basis.

11. The catalytic cracking catalyst of claim 10, wherein the clay is selected from one or more of kaolin, montmorillonite, diatomaceous earth, halloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite, and bentonite, and the alumina binder is selected from one or more of gamma-alumina, η -alumina, theta-alumina, chi-alumina, pseudo-boehmite, monodiaspore, gibbsite, bayerite, or alumina sol;

the preparation method of the alumina containing the additive comprises the following steps:

(1) mixing the pseudoboehmite with water and acid sufficient to slurry the pseudoboehmite under agitation, wherein the acid is used in an amount such that the weight ratio of the acid to the alumina in the pseudoboehmite is from 0.01 to 0.5;

12. The catalytic cracking catalyst according to claim 6, wherein the ratio of the amount of B acid to the amount of L acid is 3.5 to 4.6.

13. The catalytic cracking catalyst of claim 7, wherein the modified Y-type molecular sieve has a relative crystal retention of 38-65% after aging at 800 ℃ under normal pressure in a 100% steam atmosphere for 17 hours.

14. A method for preparing the catalytic cracking catalyst of claim 1, comprising the steps of preparing a modified Y-type molecular sieve, forming a slurry containing the modified Y-type molecular sieve, an additive-containing alumina, clay and water, and spray-drying, wherein the additive-containing alumina contains 60 wt% to 99.5 wt% of alumina and 0.5 wt% to 40 wt% of an additive, based on the weight of the additive-containing alumina, and the additive is one or more selected from compounds containing alkaline earth metals, lanthanide metals, silicon, gallium, boron or phosphorus elements; the preparation method of the modified Y-type molecular sieve comprises the following steps:

(1) contacting the NaY molecular sieve with a rare earth salt solution to perform an ion exchange reaction, filtering, washing, and optionally drying to obtain a rare earth-containing Y-type molecular sieve with a conventional unit cell size and reduced sodium oxide content;

(2) roasting the rare earth-containing Y-type molecular sieve with the conventional unit cell size and the reduced sodium oxide content at 350-520 ℃ for 4.5-7 hours in a 30-95 volume% water vapor atmosphere, and optionally drying to obtain the Y-type molecular sieve with the reduced unit cell constant;

(3) according to SiCl₄: the Y-type molecular sieve with reduced unit cell constant is 0.1-0.7: 1, carrying out contact reaction on the Y-type molecular sieve with the reduced unit cell constant and silicon tetrachloride gas at the reaction temperature of 200-650 ℃ for 10 minutes to 5 hours, and optionally washing and optionally filtering to obtain a gas-phase ultrastable modified Y-type molecular sieve;

(4) and (4) contacting the gas-phase ultra-stable modified Y-shaped molecular sieve obtained in the step (3) with an acid solution.

15. The process of claim 14, wherein the rare earth-containing Y-type molecular sieve having a conventional unit cell size with a reduced sodium oxide content in step (1) has a unit cell constant of 2.465 to 2.472nm and a sodium oxide content of not more than 9 wt.%.

16. The process of claim 14, wherein in step (1), the rare earth-containing Y-type molecular sieve having a reduced sodium oxide content and a conventional unit cell size contains rare earth in an amount of RE₂O₃5.5 to 14 wt%, a sodium oxide content of 4 to 9 wt%, and a cell constant of 2.465nm to 2.472 nm.

17. The method of claim 14, wherein the step (1) of contacting the NaY molecular sieve with a rare earth salt solution to perform an ion exchange reaction comprises: according to the NaY molecular sieve: rare earth salt: h₂O is 1: 0.01-0.18: 5-20, mixing NaY molecular sieve, rare earth salt and water, and stirring.

18. The method of claim 14 or 17, wherein the step (1) of contacting the NaY molecular sieve with a rare earth salt solution for an ion exchange reaction comprises: mixing NaY molecular sieve with decationized water, stirring, adding rare earth salt and/or rare earth salt solution to perform ion exchange reaction, filtering, and washing; the conditions of the ion exchange reaction are as follows: the exchange temperature is 15-95 ℃, the exchange time is 30-120 minutes, and the rare earth salt solution is a rare earth salt water solution.

19. The method of claim 14, wherein the rare earth salt is a rare earth chloride or a rare earth nitrate.

20. The method as claimed in claim 14, wherein the roasting temperature in the step (2) is 380-480 ℃, the roasting atmosphere is 40-80% of water vapor atmosphere, and the roasting time is 5-6 hours.

21. The method according to claim 14, wherein the unit cell constant of the Y-type molecular sieve with reduced unit cell constant obtained in step (2) is 2.450nm to 2.462nm, and the water content of the Y-type molecular sieve with reduced unit cell constant is not more than 1 wt%.

22. The method according to claim 14, wherein the washing method in the step (3) is washing with water under the washing conditions that the molecular sieve: h₂The weight ratio of O =1: 6-15, and the washing temperature is 30-60 ℃.

23. The method according to claim 14, wherein the gas phase ultrastable modified Y-type molecular sieve obtained in step (3) is contacted with an acid solution in the weight ratio of acid to molecular sieve of 0.001-0.15: 1, the weight ratio of water to the molecular sieve is 5-20: 1, the acid is one or more of organic acid and inorganic acid, the contact time is more than 60 minutes, and the contact temperature is 80-99 ℃.

24. The method according to claim 14, wherein the acid solution in step (4) contains an organic acid and an inorganic acid with a medium strength or higher, and the weight ratio of the inorganic acid with a medium strength or higher to the molecular sieve is 0.01-0.05: 1; the weight ratio of the organic acid to the molecular sieve is 0.02-0.1: 1, the weight ratio of water to the molecular sieve is 5-20: 1, the contact temperature is 80-99 ℃, and the contact time is 1-4 hours.

25. The method according to claim 14, wherein the contacting with the acid solution in step (4) comprises contacting with a medium-strength or higher inorganic acid, and then contacting with an organic acid, under the conditions of: the weight ratio of the inorganic acid with the medium strength to the molecular sieve is 0.01-0.06: 1, the weight ratio of water to the molecular sieve is 5-20: 1, the contact time is: the contact temperature is 90-98 ℃ for 60-120 minutes; the contact conditions with the organic acid are as follows: the weight ratio of the organic acid to the molecular sieve is 0.02-0.14: 1, the weight ratio of water to the molecular sieve is 5-20: 1, the contact time is 60-120 minutes, and the contact temperature is 90-98 ℃.

26. The method of claim 24 or 25, wherein the organic acid is one or more of oxalic acid, malonic acid, succinic acid, methylsuccinic acid, malic acid, tartaric acid, citric acid, salicylic acid; the inorganic acid with the medium strength or more is one or more of phosphoric acid, hydrochloric acid, nitric acid and sulfuric acid.

27. The process of claim 16, wherein in step (1), the rare earth-containing conventional unit cell size Y-type molecular sieve having a reduced sodium oxide content has a sodium oxide content of 5.5 to 8.5 wt.%.

28. The method according to claim 23, wherein the contact time of the step (4) is 1 to 4 hours.