CN110833858A

CN110833858A - Modified Y-type molecular sieve and preparation method thereof

Info

Publication number: CN110833858A
Application number: CN201810942873.2A
Authority: CN
Inventors: 周灵萍; 沙昊; 袁帅; 姜秋桥; 张蔚琳; 陈振宇; 许明德; 田辉平
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: 2018-08-17
Filing date: 2018-08-17
Publication date: 2020-02-25
Anticipated expiration: 2038-08-17
Also published as: CN110833858B

Abstract

The present disclosure relates to a modified Y-type molecular sieve and a preparation method thereof. On the basis of the dry weight of the modified Y-type molecular sieve, the modified Y-type molecular sieve contains 5-12 wt% of rare earth elements calculated by oxides, sodium oxide with the content not exceeding 0.5 wt%, gallium oxide with the content being 0.1-2.5 wt%, and zirconium oxide with the content being 0.1-2.5 wt%; the total pore volume of the modified Y-type molecular sieve is 0.36-0.48 mL/g, and the pore volume of secondary pores with the pore diameter of 2-100 nm accounts for 20-38% of the total pore volume; the unit cell constant of the modified Y-type molecular sieve is 2.440-2.455 nm, and the lattice collapse temperature is not lower than 1060 ℃; the non-framework aluminum content of the modified Y-type molecular sieve accounts for not more than 10% of the total aluminum content, and the ratio of the B acid content to the L acid content in the strong acid content of the modified Y-type molecular sieve is not less than 3.0. The modified Y-type molecular sieve disclosed by the invention is used for processing hydrogenated LCO, has high LCO conversion efficiency, lower coke selectivity, higher gasoline yield rich in BTX aromatic hydrocarbon, high propylene yield and high concentration of propylene in liquefied gas.

Description

Modified Y-type molecular sieve and preparation method thereof

Technical Field

The present disclosure relates to a modified Y-type molecular sieve and a preparation method thereof.

Background

Light aromatic hydrocarbons such as benzene, toluene, xylene (BTX), and the like are important basic organic chemical raw materials, are widely used for producing polyesters, chemical fibers, and the like, and have been in strong demand in recent years. Light aromatic hydrocarbons such as benzene, toluene and xylene (BTX) are mainly obtained from catalytic reforming and steam cracking processes using naphtha as a raw material. Due to the shortage of naphtha raw material, the light aromatics have larger market gap.

The catalytic cracking Light Cycle Oil (LCO) is an important byproduct of catalytic cracking, is large in quantity, is rich in aromatic hydrocarbon, particularly polycyclic aromatic hydrocarbon, and belongs to poor diesel oil fraction. With the development and change of market demand and environmental protection requirement, LCO is greatly limited as a diesel blending component. The hydrocarbon composition of LCO comprises paraffin, naphthene (containing a small amount of olefin) and aromatic hydrocarbon, the hydrocarbon composition of LCO has larger difference according to different catalytic cracking raw oil and different operation severity, but the aromatic hydrocarbon is the main component of the LCO, the mass fraction is usually more than 70%, some aromatic hydrocarbon even reaches about 90%, and the rest is paraffin and naphthene. The LCO has the highest content of bicyclic aromatics, belongs to typical components of the LCO and is also a key component influencing the catalytic cracking to produce light aromatics. Under the catalytic cracking reaction condition, polycyclic aromatic hydrocarbons are difficult to open-loop crack into light aromatic hydrocarbons, and under the hydrotreating condition, the polycyclic aromatic hydrocarbons are easy to saturate into heavy monocyclic aromatic hydrocarbons such as alkylbenzene and cyclohydrocarbyl benzene (indanes, tetrahydronaphthalenes and indenes). The heavy monocyclic aromatic hydrocarbon is a potential component for producing light aromatic hydrocarbon by catalytic cracking, and can be cracked into the light aromatic hydrocarbon under the catalytic cracking condition. Therefore, LCO is a potential and cheap resource for producing light aromatics, and the production of light aromatics by a hydroprocessing-catalytic cracking technological route has important research value.

CN103923698A discloses a catalytic conversion method for producing aromatic compounds, in the method, poor quality heavy cycle oil and residual oil are subjected to hydrotreating reaction in the presence of hydrogen and hydrogenation catalysts, and reaction products are separated to obtain gas, naphtha, hydrogenated diesel oil and hydrogenated residual oil; the hydrogenated diesel oil enters a catalytic cracking device, a cracking reaction is carried out in the presence of a catalytic cracking catalyst, and a reaction product is separated to obtain dry gas, liquefied gas, catalytic gasoline rich in benzene, toluene and xylene, catalytic light diesel oil, fractions with the distillation range of 250-450 ℃ and slurry oil; wherein the distillation range of 250-450 ℃ is sent to a residual oil hydrotreater for recycling. The method makes full use of the residual oil hydrogenation condition to maximally saturate aromatic rings in the poor-quality heavy cycle oil, so that the hydrogenated diesel oil can maximally produce benzene, toluene and xylene in the catalytic cracking process.

CN104560185A discloses a catalytic conversion method for producing gasoline rich in aromatic compounds, in which catalytic cracking light cycle oil is cut to obtain light fraction and heavy fraction, wherein the heavy fraction is hydrotreated to obtain hydrogenated heavy fraction, the light fraction and the hydrogenated heavy fraction separately enter a catalytic cracking device through different nozzles in a layered manner, a cracking reaction is performed in the presence of a catalytic cracking catalyst, and a product including gasoline rich in aromatic compounds and light cycle oil is obtained by separating reaction products. The method adopts a single catalytic cracking device to process the light fraction of the light cycle oil and the hydrogenated heavy fraction and allows the light fraction and the hydrogenated heavy fraction to enter in a layering manner, so that the harsh conditions required by catalytic cracking reaction of different fractions of the light cycle oil can be optimized and met to the maximum extent, and the catalytic gasoline rich in benzene, toluene and xylene can be produced to the maximum extent.

CN104560187A discloses a catalytic conversion method for producing gasoline rich in aromatic hydrocarbons, which cuts catalytic cracking light cycle oil to obtain light fraction and heavy fraction, wherein the heavy fraction is hydrotreated to obtain hydrogenated heavy fraction, the light fraction and the hydrogenated heavy fraction separately enter different riser reactors of a catalytic cracking device respectively, and are subjected to cracking reaction in the presence of a catalytic cracking catalyst, and reaction products are separated to obtain products including gasoline rich in aromatic hydrocarbons and light cycle oil. The method adopts a single catalytic cracking device to process the light fraction and the hydrogenated heavy fraction of the light cycle oil, and can optimize and meet the harsh conditions required by the catalytic cracking reaction of different fractions of the light cycle oil to the maximum extent, thereby producing the catalytic gasoline rich in benzene, toluene and xylene to the maximum extent.

In the prior art, LCO is adopted for proper hydrogenation, most polycyclic aromatic hydrocarbons in the LCO are saturated into hydrogenated aromatic hydrocarbons containing naphthenic rings and an aromatic ring, and then cracking reaction is carried out in the presence of a catalytic cracking catalyst to produce BTX light aromatic hydrocarbons. However, the cracking performance of hydrogenated aromatics obtained by hydrogenation of LCO is inferior to that of conventional catalytic cracking raw materials, and the hydrogen transfer performance is much higher than that of general catalytic cracking raw materials, so that the conventional catalytic cracking catalyst used in the prior art cannot meet the requirements of catalytic cracking of hydrogenated LCO.

In order to better meet the requirement of catalytic cracking of hydrogenated LCO for producing BTX light aromatic hydrocarbons in high yield, the invention aims to develop a high-stability modified molecular sieve which has strong cracking capability and weaker hydrogen transfer performance simultaneously as a new active component, and further develop a catalytic cracking agent of BTX light aromatic hydrocarbons in high yield suitable for catalytic cracking of hydrogenated LCO by using the new active component, strengthen cracking reaction, control hydrogen transfer reaction, further improve the conversion efficiency of hydrogenated LCO, and furthest produce catalytic gasoline rich in benzene, toluene and xylene (BTX).

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: the commercially available USY was 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 to obtain Y-shapedThe mesoporous volume of the molecular sieve can reach 0.2-0.6 ml/g, but the crystallinity and the surface area are both 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 a high-silicon Y zeolite with a unit cell constant of 2.420-2.440 nm, which comprises subjecting NaY zeolite or Y-type zeolite which has been subjected to a ultrastable treatment to one or more ammonium exchanges, hydrothermal treatments 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 a rare earth ultrastable Y-type molecular sieve, which is characterized in that the method comprises the step of contacting an NaY molecular sieve with an ammonium salt aqueous solution containing 6-94 wt% of ammonium salt at the conditions of normal pressure and the boiling temperature of more than 90 ℃ to no more than the boiling point of the ammonium salt aqueous solution according to the weight ratio of 0.1-24 of the ammonium salt to the molecular sieveTwice or more than twice to make Na in the molecular sieve₂Reducing the O content to below 1.5 weight percent, and then contacting the molecular sieve with an aqueous solution with the rare earth salt content of 2-10 weight percent at the temperature of 70-95 ℃ to ensure that the rare earth in the molecular sieve is 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 preparation method of a rare earth-containing silicon-rich ultrastable Y-type molecular sieve, which takes NaY as a raw material and RECl as a solid₃In 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.

Disclosure of Invention

It is an object of the present disclosure to provide a modified Y-type molecular sieve having higher LCO conversion efficiency, better coke selectivity, and higher yields of aromatics-rich gasoline, and a method for making the same.

In order to achieve the above object, the first aspect of the present disclosure provides a modified Y-type molecular sieve, wherein the modified Y-type molecular sieve contains, by weight calculated as oxide, 5 to 12 wt% of rare earth elements, not more than 0.5 wt% of sodium oxide, 0.1 to 2.5 wt% of gallium oxide, and 0.1 to 2.5 wt% of zirconium oxide, based on the dry weight of the modified Y-type molecular sieve; the total pore volume of the modified Y-type molecular sieve is 0.36-0.48 mL/g, and the pore volume of secondary pores with the pore diameter of 2-100 nm accounts for 20-38% of the total pore volume; the unit cell constant of the modified Y-type molecular sieve is 2.440-2.455 nm, and the lattice collapse temperature is not lower than 1060 ℃; the proportion of non-framework aluminum content of the modified Y-type molecular sieve in the total aluminum content is not higher than 10%, and the ratio of B acid content to L acid content in strong acid content of the modified Y-type molecular sieve is not lower than 3.0.

Optionally, the pore volume of secondary pores with the pore diameter of 2-100 nm of the modified Y-type molecular sieve accounts for 28-38% of the total pore volume.

Optionally, the specific surface area of the modified Y-type molecular sieve is 600-680 m²/g。

Optionally, the non-framework aluminum content of the modified Y-type molecular sieve accounts for 5-9.5% of the total aluminum content; with n (SiO)₂)/n(Al₂O₃) And the framework silicon-aluminum ratio of the modified Y-type molecular sieve is 7-14.

Optionally, the lattice collapse temperature of the modified Y-type molecular sieve is 1060-1085 ℃.

Optionally, the ratio of the B acid amount to the L acid amount in the strong acid amount of the modified Y-type molecular sieve is 3.2-5.6; the ratio of the B acid amount to the L acid amount in the strong acid amount of the modified Y-type molecular sieve is measured at 350 ℃ by adopting a pyridine adsorption infrared method.

Optionally, the relative crystallinity of the modified Y-type molecular sieve is 70-80%.

Optionally, the modified Y-type molecular sieve has a relative crystallinity retention of 38% or more as determined by XRD after aging with 100% steam at 800 deg.C for 17 h.

Optionally, the modified Y-type molecular sieve contains, by weight calculated as oxide, 5.5-10 wt% of rare earth elements, 0.15-0.3 wt% of sodium oxide, 0.2-2 wt% of gallium oxide and 0.5-2 wt% of zirconium oxide, based on the dry weight of the modified Y-type molecular sieve; the unit cell constant of the modified Y-type molecular sieve is 2.442-2.453 nm; with n (SiO)₂)/n(Al₂O₃) The framework silica-alumina ratio of the modified Y-type molecular sieve is 7.8-12.6; the rare earth element comprises La, Ce, Pr or Nd, or a combination of two or three or four thereof.

A second aspect of the present disclosure provides a process for preparing a modified Y-type molecular sieve according to the first aspect of the present disclosure, the process comprising the steps of:

(1) contacting a NaY molecular sieve with rare earth salt for ion exchange reaction, filtering and washing for the first time to obtain the molecular sieve after ion exchange, wherein the sodium oxide content of the molecular sieve after ion exchange is not more than 9.0 percent by weight based on the dry weight of the molecular sieve after ion exchange;

(2) performing first roasting on the ion-exchanged molecular sieve at the temperature of 350-520 ℃ for 4.5-7 h in the presence of 30-95% of water vapor to obtain a molecular sieve modified by moderating hydrothermal superstability;

(3) molecular sieves and SiCl for ultrastable modification of said mild water₄Performing contact reaction, and obtaining the gas-phase ultra-stable modified molecular sieve after performing or not performing second washing and second filtering;

(4) contacting the gas-phase ultra-stable modified molecular sieve with an acid solution for acid treatment to obtain an acid-treated molecular sieve;

(5) and contacting the molecular sieve subjected to acid treatment with gallium and zirconium in a solution, and drying and carrying out second roasting to obtain the modified Y-type molecular sieve.

Optionally, the method of ion exchange reaction comprises: mixing NaY molecular sieve with water, adding rare earth salt and/or rare earth salt water solution under stirring to perform ion exchange reaction, and filtering and washing;

the conditions of the ion exchange reaction include: the temperature is 15-95 ℃, the time is 30-120 min, and the weight ratio of the NaY molecular sieve to the rare earth salt to the water is 1: (0.01-0.18): (5-20).

Optionally, the unit cell constant of the ion-exchanged molecular sieve is 2.465-2.472 nm, the rare earth content is 5.5-14 wt% calculated by oxide, and the sodium oxide content is 4-9 wt%.

Optionally, the rare earth salt is rare earth chloride or rare earth nitrate, and the rare earth element in the rare earth salt comprises La, Ce, Pr or Nd, or a combination of two or three or four of the La, Ce, Pr or Nd.

Optionally, the processing conditions of step (2) include: the first roasting is carried out for 5-6 h at 380-480 ℃ under 40-80% water vapor.

Optionally, the unit cell constant of the molecular sieve subjected to mild hydrothermal superstability modification is 2.450-2.462 nm, and the water content of the molecular sieve subjected to mild hydrothermal superstability modification is not more than 1 wt%.

Optionally, in step (3), SiCl₄The weight ratio of the molecular sieve to the gas-phase ultra-stable modified molecular sieve based on the dry weight is (0.1-0.7): 1, the temperature of the contact reaction is 200-650 ℃, and the reaction time is 10 min-5 h; the second washing method includes: washing with water until the pH value of a washing liquid is 2.5-5.0, the washing temperature is 30-60 ℃, and the weight ratio of the water consumption to the unwashed gas-phase ultra-stable modified molecular sieve is (6-15): 1.

alternatively, the acid treatment conditions in step (4) include: the acid treatment temperature is 80-99 ℃, the acid treatment time is 1-4 h, the acid solution comprises organic acid and/or inorganic acid, and the weight ratio of the acid in the acid solution, the water in the acid solution and the gas-phase ultra-stable modified molecular sieve based on the dry weight is (0.001-0.15): (5-20): 1.

optionally, the method of acid treatment in step (4) comprises: firstly, the gas-phase ultra-stable modified molecular sieve is in first contact with an inorganic acid solution, and then is in second contact with an organic acid solution;

the conditions of the first contact include: the time is 60-120 min, the contact temperature is 90-98 ℃, and the weight ratio of the inorganic acid in the inorganic acid solution, the water in the inorganic acid solution and the gas-phase ultrastable modified molecular sieve based on dry weight is (0.01-0.05): (5-20): 1; the conditions of the second contacting include: the time is 60-120 min, the contact temperature is 90-98 ℃, and the weight ratio of the organic acid in the organic acid solution, the water in the organic acid solution and the gas-phase ultrastable modified molecular sieve based on the dry weight is (0.02-0.1): (5-20): 1.

optionally, the organic acid is oxalic acid, malonic acid, succinic acid, methylsuccinic acid, malic acid, tartaric acid, citric acid, or salicylic acid, or a combination of two or three or four thereof; the inorganic acid is phosphoric acid, hydrochloric acid, nitric acid or sulfuric acid, or a combination of two or three or four of them.

Optionally, the method of contacting of step (5) comprises: uniformly mixing the molecular sieve after acid treatment with an aqueous solution containing a gallium salt and a zirconium salt, and then standing the mixture at 24-36 ℃ for 15-40 h, wherein the weight ratio of gallium in terms of oxides, zirconium in terms of oxides and the molecular sieve after acid treatment in terms of dry weight in the aqueous solution containing the gallium salt and the zirconium salt is (0.001-0.025): (0.001-0.025): 1, the weight ratio of water in the aqueous solution to the acid-treated molecular sieve on a dry basis is (2-3): 1.

alternatively, in the step (5), the conditions of the second firing include: the roasting temperature is 450-600 ℃, and the roasting time is 2-5 h.

According to the technical scheme, the preparation method of the modified Y-type molecular sieve provided by the disclosure comprises the steps of carrying out rare earth exchange, hydrothermal hyperstabilization treatment and gas phase hyperstabilization treatment on the Y-type molecular sieve, cleaning the pore channels of the molecular sieve by combining acid treatment, and modifying by adopting active elements gallium and zirconium, so that the high-silicon Y-type molecular sieve which is high in crystallinity, thermal stability and hydrothermal stability and is rich in a secondary pore structure can be prepared, the molecular sieve has higher crystallinity under the condition that the hyperstabilization degree is greatly improved, 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 that the molecular sieve has higher secondary pores. The modified Y-type molecular sieve disclosed by the invention can be used as an active component of a catalytic cracking catalyst and used for processing catalytic cracking of hydrogenated LCO; the catalytic cracking catalyst using the molecular sieve as an active component is used for processing hydrogenated LCO, and has high LCO conversion efficiency, lower coke selectivity, higher BTX-rich gasoline yield and high propylene yield.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Detailed Description

The following describes in detail specific embodiments of the present disclosure. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

The first aspect of the disclosure provides a modified Y-type molecular sieve, wherein the modified Y-type molecular sieve comprises, by weight calculated on an oxide basis, 5 to 12 wt% of rare earth elements, not more than 0.5 wt% of sodium oxide, 0.1 to 2.5 wt% of gallium oxide, and 0.1 to 2.5 wt% of zirconium oxide; the total pore volume of the modified Y-type molecular sieve is 0.36-0.48 mL/g, and the pore volume of secondary pores with the pore diameter of 2-100 nm accounts for 20-38% of the total pore volume; the unit cell constant of the modified Y-type molecular sieve is 2.440-2.455 nm, and the lattice collapse temperature is not lower than 1060 ℃; the proportion of non-framework aluminum content of the modified Y-type molecular sieve in the total aluminum content is not higher than 10%, and the ratio of B acid content to L acid content in strong acid content of the modified Y-type molecular sieve is not lower than 3.0.

The modified Y-type molecular sieve disclosed by the invention has the advantages of high degree of ultrastability, higher crystallinity, uniform aluminum distribution in the molecular sieve, low non-framework aluminum content, smooth secondary pore channels and higher specific surface area under the condition of higher secondary pores. The modified Y-type molecular sieve has high LCO conversion efficiency when being used for processing hydrogenated LCO, has lower coke selectivity and has higher gasoline yield rich in BTX.

The modified Y-type molecular sieve is a rare earth-containing ultrastable Y-type molecular sieve rich in secondary pores, wherein the secondary pore distribution curve of the molecular sieve with the pore diameter of 2 nm-100 nm is in double-variable pore distribution, 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 volume of the secondary pores with the pore diameter of 2-100 nm accounts for 28-38% or 25-38% of the total pore volume

The modified Y-type molecular sieve disclosed by the invention contains rare earth elements, and the content of the rare earth elements in the modified Y-type molecular sieve calculated by oxides can be 5-12 wt%, preferably 5.5-10 wt% on the basis of the dry weight of the modified Y-type molecular sieve. The rare earth element may include La, Ce, Pr, or Nd, or a combination of two, three, or four of them, and further, the rare earth element may include other rare earth elements besides La, Ce, Pr, and Nd.

The modified Y-type molecular sieve disclosed by the invention contains active elements of gallium and zirconium, wherein the content of gallium oxide can be 0.1-2.5 wt%, preferably 0.2-2.0 wt% or 0.3-1.8 wt%, and the content of zirconium oxide can be 0.1-2.5 wt%, preferably 0.2-2.0 wt% or 0.5-2 wt%, based on the dry weight of the molecular sieve. Within the preferable content range, the LCO is catalyzed by the modified Y-type molecular sieve with higher conversion efficiency, the coke selectivity is lower, and the gasoline and the propylene rich in BTX aromatic hydrocarbon with higher yield can be obtained.

According to the present disclosure, the modified Y-type molecular sieve may contain a small amount of sodium, and the amount of sodium oxide may be 0.05 to 0.5 wt%, preferably 0.1 to 0.4 wt%, and more preferably 0.15 to 0.3 wt%, based on the dry weight of the molecular sieve.

According to the present disclosure, the contents of rare earth elements, sodium oxide, and active elements gallium and zirconium in the modified Y-type molecular sieve can be determined by X-ray fluorescence spectrometry, respectively.

According to the disclosure, the pore structure of the modified Y-type molecular sieve can be further optimized to achieve more suitable catalytic cracking reaction performance. The total pore volume of the modified Y-type molecular sieve is preferably 0.36-0.48 mL/g, and more preferably 0.38-0.45 mL/g or 0.38-0.42 mL/g; the proportion of the pore volume of the secondary pores with the pore diameter of 2-100 nm in the total pore volume is preferably 20-38%, for example, the pore volume of the secondary pores with the pore diameter of 2.0-100 nm can be 0.08-0.18 mL/g, preferably 0.10-0.16 mL/g. In the present disclosure, the total pore volume of the molecular sieve may be determined from the adsorption isotherm according to RIPP151-90 Standard method, "petrochemical analysis method (RIPP test method)," compiled by Yankee et al, scientific Press, published in 1990), and then the micropore volume of the molecular sieve may be determined from the adsorption isotherm according to the T-plot method, and the secondary pore volume may be obtained by subtracting the micropore volume from the total pore volume.

In one embodiment of the present disclosure, the specific surface area of the modified Y-type molecular sieve may be 600-680 m²A/g, for example, of 610 to 670m²/g or 640-670 m²(ii) in terms of/g. Wherein, the specific surface area of the modified Y-type molecular sieve refers to BET specific surface area, and the specific surface area can be measured according to the ASTM D4222-98 standard method.

According to the disclosure, the unit cell constant of the modified Y-type molecular sieve is further preferably 2.440-2.455 nm, such as 2.442-2.453 nm or 2.442-2.451 nm. The lattice collapse temperature of the modified Y-type molecular sieve is preferably 1060-1085 ℃, and more preferably 1064-1081 ℃.

According to the present disclosure, the relative crystallinity of the modified Y-type molecular sieve may be not less than 70%, such as 70 to 80%, preferably not less than 71%, such as 71 to 77%. The modified Y-type molecular sieve disclosed by the invention has higher hydrothermal aging resistance, and after the modification is aged for 17 hours by 100% of water vapor at 800 ℃ under normal pressure, the retention rate of the relative crystallinity of the modified Y-type molecular sieve measured by XRD is more than 38%, for example, 38-65%, 46-60% or 52-60%. The normal pressure can be 1 atm.

Wherein, the lattice collapse temperature of the modified Y-type molecular sieve can be determined by a Differential Thermal Analysis (DTA) method. The unit cell constants and relative crystallinity of the zeolite were measured by X-ray powder diffraction (XRD) using RIPP145-90 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: framework SiO₂/Al₂O₃Molar ratio of 2 × (25.858-a)₀)/(a₀-24.191). Wherein, a₀Is a unit cell constant in

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. Wherein the relative crystallinity retention rate ═ (relative crystallinity of aged sample/relative crystallinity of fresh sample) × 100%.

The non-framework aluminum content of the modified Y-type molecular sieve is low, and the proportion of the non-framework aluminum content in the total aluminum content is not higher than 10%, preferably 3-9%, and further preferably 5-9.5% or 6-9.5%; with n (SiO)₂)/n(Al₂O₃) The framework silicon-aluminum ratio of the modified Y-type molecular sieve can be 7-14, and is preferably 7.8-13.

According to the present disclosure, in order to ensure that the modified Y-type molecular sieve has a suitable surface acid center type and strength, the ratio of the amount of the B acid to the amount of the L acid in the strong acid amount of the modified Y-type molecular sieve is preferably 3.2 to 5.6, for example, 3.3 to 5.5. The ratio of the B acid amount to the L acid amount in the strong acid amount of the modified Y-type molecular sieve, namely the ratio of the strong B acid amount to the strong L acid amount, can be measured at 350 ℃ by adopting a pyridine adsorption infrared method, wherein the strong acid amount refers to the total amount of strong acid on the surface of the molecular sieve, and the strong acid refers to acid obtained by measuring at 350 ℃ by adopting the pyridine adsorption infrared method.

In one embodiment of the present disclosure, the modified Y-type molecular sieve may contain, based on the dry weight of the modified Y-type molecular sieve, 5.5 to 10 wt% of rare earth elements in terms of oxide, 0.15 to 0.3 wt% of sodium oxide, 0.1 to 2.5 wt% of gallium oxide, for example, 0.2 to 2 wt% or 0.3 to 1.8 wt%, and 0.1 to 2.5 wt% of zirconium oxide, for example, 0.5 to 2.0 wt% or 0.2 to 2 wt%; the unit cell constant of the modified Y-type molecular sieve can be 2.442-2.453 nm; with n (SiO)₂)/n(Al₂O₃) And the framework silicon-aluminum ratio of the modified Y-type molecular sieve can be 7.8-12.6.

According to the present disclosure, the rare earth element may be of any kind, and the kind and composition thereof are not particularly limited, and in one embodiment, the rare earth element may include La, Ce, Pr, or Nd, or a combination of two or three or four thereof, and may further include other rare earth elements other than La, Ce, Pr, and Nd.

The preparation method disclosed by the invention can be used for preparing the high-silicon Y-type molecular sieve which is high in crystallinity, high in thermal stability and high in hydrothermal stability and is rich in secondary pores, the molecular sieve can have higher crystallinity under the condition that the ultrastable degree is greatly improved, the prepared molecular sieve is uniform in aluminum distribution, less in non-framework aluminum content, smooth in secondary pore channels and higher in specific surface area under the condition that the molecular sieve has higher secondary pores, and the modified Y-type molecular sieve is used for processing hydrogenated LCO and has high LCO conversion efficiency, lower coke selectivity, higher gasoline yield rich in BTX aromatic hydrocarbon and high propylene yield.

In the preparation method of the modified Y-type molecular sieve provided by the present disclosure, in step (1), the NaY molecular sieve is subjected to an ion exchange reaction with a rare earth solution to obtain a rare earth-containing Y-type molecular sieve with a conventional unit cell size and a reduced sodium oxide content, and the method of the ion exchange reaction may be well known to those skilled in the art, for example, the method of the ion exchange reaction may include: mixing NaY molecular sieve with water, adding rare earth salt and/or rare earth salt water solution while stirring for ion exchange reaction, and filtering and washing.

Wherein, the water can be decationized water and/or deionized water; the NaY molecular sieve can be purchased or prepared according to the existing method, and in one embodiment, the unit cell constant of the NaY molecular sieve can be 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 conditions of the ion exchange reaction can be conventional in the field, further, in order to promote the ion exchange reaction, in the ion exchange reaction of the NaY molecular sieve and the rare earth solution, the exchange temperature can be 15-95 ℃, preferably 20-65 ℃ or 65-95 ℃, and the exchange time can be 30-120 min, preferably 45-90 min. NaY molecular sieve (on a dry basis): rare earth salts (as RE)₂O₃Meter): h₂The weight ratio of O may be 1: (0.01-0.18): (5-20), preferably 1: (0.5-0.17): (6-14).

In one embodiment of the present disclosure, the molecular weight may be as follows NaY molecular sieve: rare earth salt: h₂(5-20) in a weight ratio of (0.01-0.18) exchanging rare earth ions and sodium ions by stirring NaY molecular sieve (also called NaY zeolite), rare earth salt and water at 15-95 ℃, for example, room temperature to 60 ℃, or 20-60 ℃, or 30-45 ℃, or 65-95 ℃, preferably for 30-120 min. Wherein mixing the NaY molecular sieve, the rare earth salt, and water can comprise slurrying the NaY molecular sieve and water prior to said slurryingAdding rare earth salt and/or a rare earth salt water solution into the solution, wherein the rare earth solution is a rare earth salt solution, and the rare earth salt is preferably rare earth chloride and/or rare earth nitrate. The rare earth may be any kind of rare earth, and the kind and composition thereof are not particularly limited, for example, one or more of La, Ce, Pr, Nd and misch metal, and 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 ion-exchanged molecular sieve obtained in the step (1) is RE₂O₃The amount of the sodium oxide is 5.5 to 14 wt%, for example, 7 to 14 wt% or 7.5 to 13 wt%, the content of the sodium oxide is preferably 5.5 to 8.5 wt% or 5.5 to 7.5 wt%, and the cell constant is 2.465nm to 2.472 nm.

In the preparation method of the modified Y-type molecular sieve, in the step (2), 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 ℃ under the atmosphere of 30-95 vol% of water vapor, preferably, in the step (2), the roasting temperature is 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 may also contain other gases, such as one or more of air, helium or nitrogen. The unit cell constant of the molecular sieve modified by the moderating hydrothermal superstability obtained in the step (2) can be 2.450 nm-2.462 nm. The solid content of the molecular sieve subjected to mild hydrothermal superstable modification in the step (2) is preferably not less than 99 weight percent.

The 30-95 vol% steam atmosphere refers to an atmosphere containing 30-90 vol% steam and the balance air, for example, a 30 vol% steam atmosphere refers to an atmosphere containing 30 vol% steam and 70 vol% air.

In order to ensure the effect of gas phase ultra-stable modification, in one embodiment of the present disclosure, the molecular sieve may be dried before step (3) to reduce the water content in the molecular sieve, so that step (3) is used for gas phase ultra-stable modificationSiCl₄The water content of the contacted molecular sieve is not more than 1 wt%, and the drying treatment is, for example, roasting drying in a rotary roasting furnace or a muffle furnace.

In the preparation method of the modified Y-type molecular sieve provided by the disclosure, the contact reaction conditions of the step (3) can be changed in a large range, and in order to further promote the gas phase superstable treatment effect, SiCl is preferably used₄The weight ratio of the modified molecular sieve (calculated on a dry basis) obtained in the step (2) to the modified molecular sieve (calculated on a dry basis) can be (0.1-0.7): 1, preferably (0.3-0.6): 1, the temperature of the contact reaction can be 200-650 ℃, preferably 350-500 ℃, and the reaction time can be 10 min-5 h, preferably 0.5-4 h; the step (3) may or may not be subjected to a second washing and a second filtration, and the second washing may or may not be followed by drying, and the second 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⁺And (3) waiting for soluble byproducts, and the washing method can comprise: washing with water until the pH value of a washing liquid is 2.5-5.0, the washing temperature can be 30-60 ℃, and the weight ratio of the water consumption to the unwashed gas-phase ultra-stable modified molecular sieve can be (5-20): 1, preferably (6-15): 1. further, the washing may be such that no free Na is detectable in the washing solution after washing⁺，Cl^-And Al³⁺And (3) plasma.

In the preparation method of the modified Y-shaped molecular sieve, in the step (4), the gas-phase ultrastable modified molecular sieve obtained in the step (3) is contacted with an acid solution for reaction so as to carry out pore cleaning modification to ensure that secondary pores are unblocked, namely pore cleaning. In an embodiment of the present disclosure, the gas phase ultrastable modified molecular sieve obtained in step (3) is contacted with an acid solution to perform a reaction, the gas phase ultrastable modified molecular sieve, that is, the gas phase ultrastable modified molecular sieve is mixed with the acid solution, and the mixture is 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, and the gas phase ultrastable modified molecular sieve is obtainedThe molecular sieve is contacted with an acid solution, wherein the acid treatment temperature can be 60-100 ℃, the preferred temperature is 80-99 ℃, the further preferred temperature is 88-98 ℃, and the acid treatment time can be 1-4 h, and the preferred time is 1-3 h; the acid solution may include an organic acid and/or an inorganic acid, and a weight ratio of the acid in the acid solution, the water in the acid solution, and the gas phase ultra-stable modified molecular sieve may be (0.001 to 0.15): (5-20): 1, preferably (0.002 to 0.1): (8-15): 1 or (0.01-0.05): (8-15): 1. wherein the washing is for removing Na remaining in the zeolite⁺，Cl^-And Al³⁺And (3) soluble by-products, the washing method may be the same as or different from the washing method of step (3), and may include, for example: washing with water until the pH value of a washing liquid is 2.5-5.0, the washing temperature can be 30-60 ℃, and the weight ratio of the water consumption to the unwashed gas-phase ultra-stable modified molecular sieve can be (5-20): 1, preferably (6-15): 1. further, the washing may be such that no free Na is detectable in the washing solution after washing⁺，Cl^-And Al³⁺And (3) plasma.

Preferably, the acid in the acid solution (aqueous acid solution) is at least one organic acid and at least one inorganic acid of medium strength or higher. The organic acid may include oxalic acid, malonic acid, succinic acid, methylsuccinic acid, malic acid, tartaric acid, citric acid, or salicylic acid, or a combination of two or three or four thereof, and the inorganic acid of medium strength or higher may include phosphoric acid, hydrochloric acid, nitric acid, or sulfuric acid, or a combination of two or three or four thereof. The contact temperature is preferably 80-99 ℃, for example 85-98 ℃, and the contact time is more than 60min, for example 60-240 min or 90-180 min. 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 (0.03-0.1): 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, (8-15): 1.

preferably, the pore cleaning modification, that is, the acid treatment in step (4), is performed in two steps, and first, an inorganic acid, preferably an inorganic acid with a medium strength or higher, is contacted with the gas-phase ultrastable modified molecular sieve for the first time, wherein the weight ratio of the inorganic acid with a medium strength or higher to the molecular sieve may be (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, (8-15): 1, the temperature of the contact reaction is 80-99 ℃, preferably 90-98 ℃, and the reaction time is 60-120 min; and then carrying out second contact on the molecular sieve obtained after the treatment and an organic acid, wherein the weight ratio of the organic acid to the molecular sieve can be (0.02-0.10): 1 is, for example, (0.05 to 0.08): 1, the weight ratio of water to the molecular sieve is preferably (5-20): 1 is, for example, (8-15): 1, the temperature of the contact reaction is 80-99 ℃, preferably 90-98 ℃, and the reaction time is 60-120 min. Wherein in the weight ratio, the molecular sieve is on a dry basis.

In the preparation method according to the present disclosure, the molecular sieve may be contacted with gallium and zirconium in solution to perform exchange and/or impregnation treatment, so as to load the active elements gallium and zirconium on the modified Y-type molecular sieve, and the contact with the active elements gallium and zirconium in solution may be performed once or multiple times, so as to introduce the required amount of active elements; to facilitate increasing the effectiveness of the gallium and zirconium modification treatment, in one embodiment of the present disclosure, the molecular sieve may be contacted with a gallium salt and a zirconium salt in solution. Wherein the molecular sieve is contacted with the gallium salt and the zirconium salt synchronously. In particular, the amount of the solvent to be used,

in one embodiment, the molecular sieve is contacted with the gallium salt and the zirconium salt simultaneously, i.e., the contacting of step (5) may comprise: and uniformly mixing the molecular sieve after the acid treatment with an aqueous solution containing gallium salt and zirconium salt, and standing. For example, the molecular sieve after acid treatment may be added to a mixture containing Ga (NO) under stirring₃)₃And Zr (NO)₃)₄The solution is dipped with gallium and zirconium components, stirred uniformly and then kept stand for 24-36 h at 15-40 ℃, preferably kept stand at room temperature. Then mixing the molecular sieve containing acid treated with Ga (NO)₃)₃And Zr (NO)₃)₄The slurry is stirred for another 20min to be uniformly mixed and then dried and roasted for the second time, and the drying can be any drying methodAnd (3) a method such as flash evaporation drying, drying and air flow drying, wherein in one mode, the drying method is to transfer the slurry into a rotary evaporator for water bath heating and rotary evaporation, and the second roasting can comprise roasting the evaporated material in a rotary roasting furnace at 450-600 ℃ for 2-5 h, and preferably 480-580 ℃ for 2.2-4.5 h.

Wherein the gallium salt may be Ga (NO)₃)₃、Ga₂(SO₄)₃Or GaCl₃Or a combination of two or three thereof, preferably Ga (NO)₃)₃An aqueous solution; the zirconium salt may be Zr (NO)₃)₄、Zr(SO₄)₂Or ZrCl₄Or a combination of two or three thereof, preferably Zr (NO)₃)₄. The weight ratio of gallium in terms of oxide, zirconium in terms of oxide and the acid-treated molecular sieve in terms of dry weight in the aqueous solution containing the gallium salt and the zirconium salt may be (0.001 to 0.025): (0.001-0.025): 1, preferably (0.002 to 0.02): (0.002-0.02): 1; the weight ratio of water in the aqueous solution containing the gallium salt and the zirconium salt to the molecular sieve subjected to acid treatment on a dry basis can be (2-3): 1, preferably (2.2-2.6): 1.

in another embodiment, the molecular sieve may be contacted with the gallium salt and the zirconium salt in steps, such as contacting the molecular sieve with an aqueous solution comprising the gallium salt and then with an aqueous solution comprising the zirconium salt; alternatively, the molecular sieve is contacted with the aqueous solution containing the zirconium salt prior to contacting with the aqueous solution containing the gallium salt under the same conditions as described above, such as temperature, time, and concentration of gallium and zirconium.

In one embodiment of the present disclosure, a method of preparing a modified Y-type molecular sieve comprises the steps of:

(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 the molecular sieve after ion exchange, wherein the molecular sieve after ion exchange has the advantages of reduced sodium oxide content, rare earth element content and conventional unit cell size; the ion exchange is carried out for 30-120 min under the conditions of stirring and the temperature of 15-95 ℃, preferably 65-95 ℃;

(2) roasting the ion-exchanged molecular sieve for 4.5-7 h at 350-480 ℃ in an atmosphere containing 30-90 vol% of water vapor, and drying to obtain a molecular sieve modified by the moderated hydrothermal superstability, wherein the water content of the molecular sieve modified by the moderated hydrothermal superstability is lower than 1 wt%, and the unit cell constant of the molecular sieve modified by the moderated hydrothermal superstability is reduced to 2.450-2.462 nm;

(3) mixing the molecular sieve sample modified by the mild hydrothermal superstability with SiCl vaporized by heating₄Gas contact of SiCl₄: the weight ratio of the molecular sieve (calculated by dry basis) for moderating hydrothermal superstable modification is (0.1-0.7): 1, carrying out contact reaction for 10min to 5h at the temperature of 200-650 ℃, optionally washing and optionally filtering to obtain a gas-phase ultra-stable modified molecular sieve;

(4) and (4) contacting the gas-phase ultra-stable modified molecular sieve obtained in the step (3) with an acid solution for acid treatment modification. Mixing the gas-phase ultra-stable modified molecular sieve obtained in the step (3), inorganic acid with medium strength and water, contacting at 80-99 ℃, preferably 90-98 ℃, for at least 30min, such as 60-120 min, then adding organic acid, contacting at 80-99 ℃, preferably 90-98 ℃, for at least 30min, such as 60-120 min, filtering, optionally washing and optionally drying to obtain the acid-treated molecular sieve; wherein the preferable weight ratio of the organic acid to the gas-phase ultra-stable modified molecular sieve calculated by dry basis is (0.02-0.10): 1, the weight ratio of the inorganic acid with the medium strength or more to the gas-phase super-stable modified molecular sieve calculated by dry basis is (0.01-0.05): 1, the weight ratio of water to the gas-phase ultra-stable modified molecular sieve is (5-20): 1.

(5) adding the molecular sieve subjected to acid treatment obtained in the step (4) into Ga (NO) while stirring₃)₃And Zr (NO)₃)₄The mixed solution of (A) and (B) is impregnated with a gallium component, and the molecular sieve after acid treatment is mixed with a compound containing Ga (NO)₃)₃And Zr (NO)₃)₄The mixed solution of (1) is stirred uniformly and then is stood at room temperature, wherein Ga (NO)₃)₃And Zr (NO)₃)₄Ga (NO) contained in the mixed solution of (1)₃)₃In an amount of Ga₂O₃The weight ratio of the acid-treated molecular sieve to the acid-treated molecular sieve is 0.1-2.5 wt%, and the weight ratio of the acid-treated molecular sieve to the acid-treated molecular sieve is calculated by mixing the solutionZr (NO) contained₃)₄In an amount of ZrO₂The weight ratio of the molecular sieve to the molecular sieve is 0.1-2.5 wt%, and Ga (NO)₃)₃And Zr (NO)₃)₄The amount of water added to the mixed solution is equal to (2-3): 1 on a dry basis, the soaking time is 24 hours, and then the modified Y-containing molecular sieve and Ga (NO) are added₃)₃And Zr (NO)₃)₄And stirring the mixed slurry for 20min to uniformly mix the slurry, transferring the mixed material to a rotary evaporator to slowly and uniformly heat and rotatably evaporate the mixed material to dryness, and then putting the evaporated material into a muffle furnace to roast the evaporated material at 450-600 ℃ for 2-5 h to obtain the modified Y molecular sieve disclosed by the invention.

The following examples further illustrate the present disclosure, but are not intended to limit the same.

In the examples and comparative examples described below, the NaY molecular sieve (also known as NaY zeolite) was supplied by the zeuginese corporation, petrochemical catalyst ltd, china, and had a sodium oxide content of 13.5 wt% and a framework silica to alumina ratio (SiO-to-alumina ratio)₂/Al₂O₃Molar ratio) of 4.6, unit cell constant of 2.470nm, relative crystallinity of 90%; the rare earth chloride, the rare earth nitrate, the gallium nitrate and the zirconium nitrate are chemically pure reagents produced in Beijing chemical plants. The pseudoboehmite is an industrial product produced by Shandong aluminum factories, and the solid content is 61 percent by weight; the kaolin is kaolin specially used for a cracking catalyst produced by Suzhou China kaolin company, and the solid content is 76 percent by weight; the alumina sol was provided by the Qilu division of China petrochemical catalyst, Inc., in which the alumina content was 21 wt%.

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 RIPP145-90 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: framework SiO₂/Al₂O₃Molar ratio of 2 × (25.858-a)₀)/(a₀-24.191). Wherein, a₀Is a unit cell constant in

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 lattice 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. The experimental method for measuring the acid content at 350 ℃ 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 350 ℃, and vacuumizing to 10 DEG C^-3Desorbing for 30min under Pa, reducing to room temperature for spectrography, scanning wave number range: 1400cm^-1～1700cm^-1And obtaining the pyridine absorption infrared spectrogram of the sample desorbed at 350 ℃. According to pyridine absorption infrared spectrogram of 1540cm^-1And 1450cm^-1The strength of the adsorption peak is characterized to obtain the medium-strength molecular sieveRelative 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: the total pore volume of the molecular sieve was determined from the adsorption isotherm according to RIPP151-90 Standard method, "petrochemical analysis method (RIPP test method)," compiled by Yankee corporation, published in 1990 ", then the micropore volume of the molecular sieve was determined from the adsorption isotherm according to the T-plot method, and the secondary pore volume was obtained by subtracting the micropore volume from the total 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 60min, 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, the unit cell constant is 2.471nm, and the rare earth content is 8.8 weight percent calculated by oxide; then, the mixture is sent into a roasting furnace to be roasted for 6 hours at the temperature of 390 ℃ under the condition of 50% of water vapor (the atmosphere contains 50% of water vapor by volume); then, roasting for 2.5h at 500 ℃ in a dry air atmosphere (the water vapor content is lower than 1 volume percent) to ensure that the water content is lower than 1 weight percent, thus obtaining the Y-type molecular sieve with the reduced unit cell constant, wherein the unit cell constant is 2.455 nm; then, directly feeding the Y-shaped molecular sieve material with the reduced unit cell constant into a continuous gas-phase ultra-stable reactor for 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 molecular sieve with decreased unit cell constant is 0.5: 1, the feeding amount of the molecular sieve is 800kg/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 molecular sieve material (2) was added to the secondary exchange tank in a weight of 2000kg (dry basis), stirred well, and then 0.6m hydrochloric acid was added thereto in a concentration of 10% by weight³Heating to 90 deg.C, stirring for 60min, adding 140kg citric acid, stirring at 90 deg.C for 60min, filtering, washing, adding the filter cake to 4000L of water-soluble solution containing 36.67kgGa (NO)₃)₃·9H₂O and 128.94kgZr (NO)₃)₄·5H₂Impregnating a gallium component and a zirconium component in a solution of OAnd mixing the modified Y molecular sieve with Ga (NO)₃)₃And Zr (NO)₃)₄The mixed solution is stirred uniformly and then stands at room temperature for 24 hours, and then the modified Y molecular sieve and Ga (NO) are mixed₃)₃And Zr (NO)₃)₄And stirring the mixed slurry for 20min to uniformly mix the slurry, transferring the mixed material to a rotary evaporator to slowly and uniformly heat and rotatably evaporate the mixed material to dryness, and then putting the evaporated material into a muffle furnace to roast the dried material at 550 ℃ for 2.5h to obtain a modified Y-type molecular sieve (molecular sieve is also called zeolite) product which is recorded as SZ 1. The physicochemical properties thereof are shown in Table 1.

After SZ1 is aged for 17h at 800 ℃, 1atm and 100 percent of water vapor in a naked state, the relative crystallinity of the molecular sieve before and after the SZ1 is aged is analyzed by an XRD method, and the retention rate of the relative crystallinity after the aging is calculated, and the result is shown in Table 2, wherein: relative crystallinity retention ═ relative crystallinity of aged sample/relative crystallinity of fresh sample x 100%.

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 evenly at 90 ℃, and then adding 800L RECl₃Solutions (RECl)₃Rare earth concentration in solution as RE₂O₃Calculated as 319g/L), stirring for 60 min; 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 and the reduced sodium oxide content, wherein the sodium oxide content is 5.5 weight percent, the unit cell constant is 2.471nm, and the rare earth content is 11.3 weight percent calculated by oxide; then, the mixture is sent into a roasting furnace to be roasted for 5.5 hours at the temperature (atmosphere temperature) of 450 ℃ 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, directly feeding the Y-shaped molecular sieve material with reduced unit cell constant into continuous gasAnd carrying out gas-phase hyperstable reaction in the phase hyperstable reactor. 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 0.25: 1, the feeding amount of the molecular sieve is 800kg/h, and the reaction temperature is 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 tank³The decationized water was added to a secondary exchange tank in such a manner that the weight of the molecular sieve material was 2000kg (dry basis weight), and the mixture was stirred uniformly, and then a 7 wt% sulfuric acid solution was added thereto in an amount of 0.9m³Heating to 93 deg.C, stirring for 80min, adding 70kg citric acid and 50kg tartaric acid, stirring at 93 deg.C for 70min, filtering, washing, adding 4500L filter cake dissolved with 74.41kg Ga (NO)₃)₃·9H₂O and 71.63kgZr (NO)₃)₄·5H₂Impregnating the solution of O with gallium component and zirconium component, and mixing the modified Y molecular sieve with the solution containing Ga (NO)₃)₃And Zr (NO)₃)₄The mixed solution is stirred uniformly and then stands at room temperature for 24 hours, and then the modified Y molecular sieve and Ga (NO) are mixed₃)₃And Zr (NO)₃)₄And stirring the mixed slurry for 20min to uniformly mix the slurry, transferring the mixed material to a rotary evaporator to slowly and uniformly heat and rotatably evaporate the mixed material to dryness, and then putting the evaporated material into a muffle furnace to roast the dried material for 3h at 500 ℃ to obtain a modified Y-shaped molecular sieve product, wherein the molecular sieve product is recorded as SZ 2. The physicochemical properties thereof are shown in Table 1.

After SZ2 is aged for 17h at 800 ℃ by 100% steam in a naked state, the crystallinity of the zeolite before and after the SZ2 is aged is analyzed by an XRD method, and the relative crystallinity retention rate after the aging is calculated, and the result is shown in Table 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 20m³DecationizingStirring in a water exchange tank at 95 deg.C, and adding 570L RECl₃Solutions (RECl)₃Rare earth concentration in solution as RE₂O₃319g/L), continuously stirring for 60min, filtering, washing, continuously feeding filter cakes into a flash drying furnace for drying to obtain 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 7.5 weight percent, the unit cell constant is 2.471nm, and the rare earth content is 8.5 weight percent calculated by oxide; 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 1.5h, 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 feeding amount of the molecular sieve is 800kg/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 decationized water was added to a secondary exchange tank in a weight of 2000kg (dry basis) of the molecular sieve material, stirred uniformly, and then 1.2m of 5 wt% nitric acid was slowly added thereto³Heating to 95 deg.C, stirring for 90min, adding citric acid 90kg and oxalic acid 40kg, stirring at 93 deg.C for 70min, filtering, washing, and adding the filter cake to 4800L of solution containing 110.03kg Ga (NO)₃)₃·9H₂O and 43.1kgZr (NO)₃)₄·5H₂Impregnating the solution of O with gallium component and zirconium component, and mixing the modified Y molecular sieve with the solution containing Ga (NO)₃)₃And Zr (NO)₃)₄The mixed solution is stirred uniformly and then stands at room temperature for 24 hours, and then the modified Y molecular sieve and Ga (NO) are mixed₃)₃And Zr (NO)₃)₄And stirring the mixed slurry for 20min to uniformly mix the slurry, transferring the mixed material to a rotary evaporator to slowly and uniformly heat and rotatably evaporate the mixed material to dryness, putting the evaporated material into a muffle furnace to roast the dried material at the temperature of 600 ℃ for 2h to obtain a modified Y-type molecular sieve product, wherein the sample is recorded as SZ 3. The physicochemical properties thereof are shown in Table 1.

After aging SZ3 in a naked state by using 100% steam at 800 ℃ for 17h, the crystallinity of the zeolite before and after aging of SZ3 is analyzed by an XRD method, and the retention rate of the relative crystallinity after aging is calculated, and the result is shown in Table 2.

Example 4

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 60min, 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, the unit cell constant is 2.471nm, and the rare earth content is 8.8 weight percent calculated by oxide; then, the mixture is sent into a roasting furnace to be roasted for 4.5 hours at the temperature of 365 ℃ under the condition of 30% of water vapor (the atmosphere contains 30% of water vapor by volume); then, roasting for 2.5h at 500 ℃ in a dry air atmosphere (the water vapor content is lower than 1 volume percent) to ensure that the water content is lower than 1 weight percent, thus obtaining the Y-type molecular sieve with the reduced unit cell constant, wherein the unit cell constant is 2.460 nm; then, directly feeding the Y-shaped molecular sieve material with the reduced unit cell constant into a continuous gas-phase ultra-stable reactor for 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 0.2: 1, the feeding amount of the molecular sieve is 800kg/h, and the reaction temperature is 250 ℃. Gas phase superstable reacted molecular sieve material passing gasThe solid separator is separated and then sent into a secondary exchange tank, and 20m is added in advance in the secondary exchange tank³The molecular sieve material (2) was added to the secondary exchange tank in a weight of 2000kg (dry basis), stirred well, and then 0.2m hydrochloric acid was added thereto in a concentration of 10% by weight³Heating to 85 deg.C, stirring for 60min, filtering, washing, adding the filter cake to 4000L of solution containing 36.67kgGa (NO)₃)₃·9H₂O and 128.94kgZr (NO)₃)₄·5H₂Impregnating the solution of O with gallium component and zirconium component, and mixing the modified Y molecular sieve with the solution containing Ga (NO)₃)₃And Zr (NO)₃)₄The mixed solution is stirred uniformly and then stands at room temperature for 24 hours, and then the modified Y molecular sieve and Ga (NO) are mixed₃)₃And Zr (NO)₃)₄And stirring the mixed slurry for 20min to uniformly mix the slurry, transferring the mixed material to a rotary evaporator to slowly and uniformly heat and rotatably evaporate the mixed material to dryness, and then putting the evaporated material into a muffle furnace to roast the dried material at 550 ℃ for 2.5h to obtain a modified Y-type molecular sieve (molecular sieve is also called zeolite) product which is recorded as SZ 4. The physicochemical properties thereof are shown in Table 1.

After SZ4 is aged for 17h at 800 ℃, 1atm and 100% steam in a naked state, the relative crystallinity of the molecular sieve before and after the SZ4 is aged is analyzed by an XRD method, and the retention rate of the relative crystallinity after the aging is calculated, and the result is shown in Table 2.

Comparative example 1

Adding 2000g NaY molecular sieve (dry basis) into 20L of decationized aqueous solution, stirring to mix well, adding 1000g (NH)₄)₂SO₄Stirring, heating to 90-95 deg.C, holding for 1h, filtering, washing, drying the filter cake at 120 deg.C, performing hydrothermal modification treatment (at 650 deg.C, roasting with 100% water vapor for 5h), adding into 20L of decationized aqueous solution, stirring, mixing, adding 1000g (NH)₄)₂SO₄Stirring, heating to 90-95 deg.C, maintaining for 1h, filtering, washing, drying filter cake at 120 deg.C to obtain Y-type molecular sieve with unit cell constant of 2.454nm and sodium oxide content of 1.3 wt%, and performing second hydrothermal modification treatment (at 650 deg.C and 10 deg.C)Roasting for 5h under 0 percent of water vapor) 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. The physicochemical properties thereof are shown in Table 1. After the DZ1 is aged for 17h at 800 ℃ by 100% steam in a naked state, the crystallinity of the zeolite before and after aging of the DZ1 is analyzed by an XRD method, and the relative crystallinity retention rate after aging is calculated, and the result is shown in Table 2.

Comparative example 2

Adding 2000g NaY molecular sieve (dry basis) into 20L of decationized aqueous solution, stirring to mix well, adding 1000g (NH)₄)₂SO₄Stirring, heating to 90-95 ℃ for 1h, filtering, washing, and drying a filter cake at 120 ℃ to obtain a Y-type molecular sieve with a unit cell constant of 2.470nm and a sodium oxide content of 5.0 wt%; then carrying out hydrothermal modification treatment under the following conditions: 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 900g (NH)₄)₂SO₄Stirring, heating to 90-95 ℃, keeping for 1h, 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 5h) to obtain the rare earth-containing hydrothermal ultrastable Y-type molecular sieve marked as DZ2, wherein the hydrothermal ultrastable Y-type molecular sieve is hydrothermally ultrastable twice through ion exchange twice. The physicochemical properties thereof are shown in Table 1. After the DZ2 is aged for 17h at 800 ℃ by 100% steam in a naked state, the crystallinity of the zeolite before and after aging of the DZ2 is analyzed by an XRD method, and the relative crystallinity retention rate after aging is calculated, and the result is shown in Table 2.

Comparative example 3

Adding 2000kg NaY molecular sieve (dry basis) to 20m³Stirring in water to mix well, adding 650L RE (NO)₃)₃Stirring the solution (319g/L), heating to 90-95 ℃ for 1h, 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, and roasting for 2h to ensure that the water content is lower than 1 wt%, thereby obtaining the normal cell2.471nm, sodium oxide content 6.7 wt.%, based on RE₂O₃And (3) counting the Y-type molecular sieve with the rare earth content of 9.5 weight percent, and then sending the dried molecular sieve material into a continuous gas-phase hyperstable reactor for gas-phase hyperstable 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 feeding amount of the molecular sieve is 800kg/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 weight of the molecular sieve material added into the secondary exchange tank is 2000kg (dry basis weight), the mixture is stirred evenly, and then 5 weight percent nitric acid of 1.2m is slowly added³And heating to 95 ℃, continuing to stir for 90min, then adding 90kg of citric acid and 40kg of oxalic acid, continuing to stir for 70min at 93 ℃, filtering, washing, sampling and drying, and recording the sample as DZ 3. The physicochemical properties thereof are shown in Table 1. After the DZ3 is aged by 100% steam at 800 ℃ for 17h in a naked state, the crystallinity of the zeolite before and after the aging of the DZ3 is analyzed by an XRD method, and the relative crystallinity retention rate after the aging is calculated, and the results are shown in Table 2.

Comparative example 4

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 60min, 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, the unit cell constant is 2.471nm, and the rare earth content is 8.8 weight percent calculated by oxide; then, the mixture is sent into a roasting furnace to be roasted for 6 hours at the temperature of 390 ℃ under the condition of 50% of water vapor (the atmosphere contains 50% of water vapor by volume); then, the air atmosphere was dried (water vapor) at a temperature of 500 deg.CSteam content less than 1 vol%) and roasting for 2.5h to make water content less than 1 wt% to obtain Y-type molecular sieve with reduced unit cell constant of 2.455 nm; then, directly feeding the Y-shaped molecular sieve material with the reduced unit cell constant into a continuous gas-phase ultra-stable reactor for 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 molecular sieve with decreased unit cell constant is 0.5: 1, the feeding amount of the molecular sieve is 800kg/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 molecular sieve material (2) was added to the secondary exchange tank in a weight of 2000kg (dry basis), stirred well, and then 0.6m hydrochloric acid was added thereto in a concentration of 10% by weight³Heating to 90 ℃, stirring for 60min, then adding 140kg of citric acid, continuously stirring for 60min at 90 ℃, filtering, washing and drying, then transferring the mixed material to a rotary evaporator for slowly and uniformly heating, rotatably evaporating to dryness, and then putting the evaporated material into a muffle furnace for roasting for 2.5h at 550 ℃, thereby obtaining a modified Y-type molecular sieve (molecular sieve is also called zeolite) product, which is recorded as DZ 4. The physicochemical properties thereof are shown in Table 1.

After the DZ4 is aged for 17h at 800 ℃ by 100% steam in a naked state, the crystallinity of the zeolite before and after aging of the DZ4 is analyzed by an XRD method, and the relative crystallinity retention rate after aging is calculated, and the result is shown in Table 2.

Comparative example 5

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 60min, filtering, washing, and sending a filter cake into a flash evaporation drying furnace for drying; obtaining a reduced sodium oxide contentThe rare earth-containing Y-type molecular sieve with the conventional unit cell size has the sodium oxide content of 7.0 percent by weight, the unit cell constant of 2.471nm and the rare earth content of 8.8 percent by weight calculated by oxide; then, the mixture is sent into a roasting furnace to be roasted for 6 hours at the temperature of 390 ℃ under the condition of 50% of water vapor (the atmosphere contains 50% of water vapor by volume); then, roasting for 2.5h at 500 ℃ in a dry air atmosphere (the water vapor content is lower than 1 volume percent) to ensure that the water content is lower than 1 weight percent, thus obtaining the Y-type molecular sieve with the reduced unit cell constant, wherein the unit cell constant is 2.455 nm; then, directly feeding the Y-shaped molecular sieve material with the reduced unit cell constant into a continuous gas-phase ultra-stable reactor for 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 molecular sieve with decreased unit cell constant is 0.5: 1, the feeding amount of the molecular sieve is 800kg/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 molecular sieve material (2) was added to the secondary exchange tank in a weight of 2000kg (dry basis), stirred well, and then 0.6m hydrochloric acid was added thereto in a concentration of 10% by weight³Heating to 90 deg.C, stirring for 60min, adding 140kg citric acid, stirring at 90 deg.C for 60min, filtering, washing, adding filter cake to 4000L of solution containing 267.5kg Ga (NO)₃)₃·9H₂O and 195.51kgZr (NO)₃)₄·5H₂Soaking gallium component and zirconium component in mixed solution of O, and mixing the modified Y molecular sieve with Ga (NO)₃)₃And Zr (NO)₃)₄Stirring the mixed solution uniformly, standing at room temperature for 24h, and then mixing the solution containing the modified Y molecular sieve and Ga (NO)₃)₃And Zr (NO)₃)₄Stirring the mixed slurry for 20min to mix uniformly, transferring the mixed material to a rotary evaporator for slow and uniform heating and rotary evaporation to dryness, placing the evaporated material in a muffle furnace for roasting at 550 ℃ for 2.5h to obtain a modified Y-type molecular sieve (molecular sieve is also called zeolite) product, and recording the product asDZ 5. The physicochemical properties thereof are shown in Table 1.

After DZ5 is aged for 17h at 800 ℃, 1atm and 100% water vapor in a naked state, the relative crystallinity of the molecular sieve before and after the aging of DZ5 is analyzed by an XRD method, and the retention rate of the relative crystallinity after the aging is calculated, and the result is shown in Table 2.

Comparative example 6

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 60min, 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, the unit cell constant is 2.471nm, and the rare earth content is 8.8 weight percent calculated by oxide; then, the mixture is sent into a roasting furnace to be roasted for 6 hours at the temperature of 390 ℃ under the condition of 50% of water vapor (the atmosphere contains 50% of water vapor by volume); then, roasting for 2.5h at 500 ℃ in a dry air atmosphere (the water vapor content is lower than 1 volume percent) to ensure that the water content is lower than 1 weight percent, thus obtaining the Y-type molecular sieve with the reduced unit cell constant, wherein the unit cell constant is 2.455 nm; then, directly feeding the Y-shaped molecular sieve material with the reduced unit cell constant into a continuous gas-phase ultra-stable reactor for 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 feeding amount of the molecular sieve is 800kg/h, and the reaction temperature is 400 ℃. 20m for molecular sieve material after gas phase superstable reaction³The decationized water was washed and then filtered, and the filter cake was added to 4000L of a solution containing 36.67kgGa (NO) while stirring₃)₃·9H₂O and 128.94kgZr (NO)₃)₄·5H₂Impregnating the solution of O with gallium component and zirconium component, and mixing the modified Y molecular sieve with the solution containing Ga (NO)₃)₃And Zr (NO)₃)₄The mixed solution is stirred uniformly and then stands at room temperature for 24 hours, and then the modified Y molecular sieve and Ga (NO) are mixed₃)₃And Zr (NO)₃)₄And stirring the mixed slurry for 20min to uniformly mix the slurry, transferring the mixed material to a rotary evaporator to slowly and uniformly heat and rotatably evaporate the mixed material to dryness, and then putting the evaporated material into a muffle furnace to roast the dried material at 550 ℃ for 2.5h to obtain a modified Y-type molecular sieve (molecular sieve is also called zeolite) product, which is recorded as DZ 6. The physicochemical properties thereof are shown in Table 1.

After DZ6 is aged for 17h at 800 ℃, 1atm and 100% water vapor in a naked state, the relative crystallinity of the molecular sieve before and after the aging of DZ6 is analyzed by an XRD method, and the retention rate of the relative crystallinity after the aging is calculated, and the result is shown in Table 2.

Comparative example 7

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 60min, 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, the unit cell constant is 2.471nm, and the rare earth content is 8.8 weight percent calculated by oxide; then, the mixture is sent into a roasting furnace to be roasted for 6 hours at the temperature of 390 ℃ under the condition of 50% of water vapor (the atmosphere contains 50% of water vapor by volume); then, roasting for 2.5h at 500 ℃ in a dry air atmosphere (the water vapor content is lower than 1 volume percent) to ensure that the water content is lower than 1 weight percent, thus obtaining the Y-type molecular sieve with the reduced unit cell constant, wherein the unit cell constant is 2.455 nm; then, directly feeding the Y-shaped molecular sieve material with the reduced unit cell constant into a continuous gas-phase ultra-stable reactor for gas-phase ultra-stable reaction. The gas phase ultra-stable reaction process of the molecular sieve in the continuous gas phase ultra-stable reactor and the subsequent tail gas absorption process thereof are carried out according to the embodiment disclosed in the CN103787352A patent1 under the process conditions of SiCl₄: weight ratio of Y-type molecular sieve with decreased unit cell constant is 0.5: 1, the feeding amount of the molecular sieve is 800kg/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 molecular sieve material (2) was added to the secondary exchange tank in a weight of 2000kg (dry basis), stirred well, and then 0.6m hydrochloric acid was added thereto in a concentration of 10% by weight³Heating to 90 deg.C, stirring for 60min, adding 140kg citric acid, stirring at 90 deg.C for 60min, filtering, washing, adding filter cake to 4000L of water-soluble 60.88kg Zr (NO)₃)₄·5H₂Impregnating the zirconium component in the solution of O, and mixing the modified Y molecular sieve with Zr (NO)₃)₄The solution is stirred evenly and then stands at room temperature for 24 hours, and then the solution containing the modified Y molecular sieve and Zr (NO)₃)₄And stirring the slurry for 20min to mix uniformly, transferring the mixed material to a rotary evaporator to slowly and uniformly heat and rotatably evaporate the mixed material to dryness, and then putting the evaporated material into a muffle furnace to roast at 550 ℃ for 2.5h to obtain a modified Y-type molecular sieve (the molecular sieve is also called zeolite) product, which is recorded as DZ 7. The physicochemical properties thereof are shown in Table 1.

After DZ7 is aged for 17h at 800 ℃, 1atm and 100% water vapor in a naked state, the relative crystallinity of the molecular sieve before and after the aging of DZ7 is analyzed by an XRD method, and the retention rate of the relative crystallinity after the aging is calculated, and the result is shown in Table 2.

Comparative example 8

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 60min, filtering, washing, and sending a filter cake into a flash evaporation drying furnace for drying; obtaining rare earth-containing Y-type molecules of conventional unit cell size with reduced sodium oxide contentA sieve with a sodium oxide content of 7.0 wt%, a unit cell constant of 2.471nm, and a rare earth content of 8.8 wt% in terms of oxide; then, the mixture is sent into a roasting furnace to be roasted for 6 hours at the temperature of 390 ℃ under the condition of 50% of water vapor (the atmosphere contains 50% of water vapor by volume); then, roasting for 2.5h at 500 ℃ in a dry air atmosphere (the water vapor content is lower than 1 volume percent) to ensure that the water content is lower than 1 weight percent, thus obtaining the Y-type molecular sieve with the reduced unit cell constant, wherein the unit cell constant is 2.455 nm; then, directly feeding the Y-shaped molecular sieve material with the reduced unit cell constant into a continuous gas-phase ultra-stable reactor for 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 molecular sieve with decreased unit cell constant is 0.5: 1, the feeding amount of the molecular sieve is 800kg/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 molecular sieve material (2) was added to the secondary exchange tank in a weight of 2000kg (dry basis), stirred well, and then 0.6m hydrochloric acid was added thereto in a concentration of 10% by weight³Heating to 90 deg.C, stirring for 60min, adding 140kg citric acid, stirring at 90 deg.C for 60min, filtering, washing, adding the filter cake to 4000L of 71.33kgGa (NO) solution₃)₃·9H₂Soaking gallium component in O solution, and mixing the modified Y molecular sieve with Ga (NO)₃)₃The solution is stirred evenly and then stands at room temperature for 24 hours, and then the solution containing the modified Y molecular sieve and Ga (NO) is mixed₃)₃And stirring the slurry for 20min to mix uniformly, transferring the mixed material to a rotary evaporator to slowly and uniformly heat and rotatably evaporate the mixed material to dryness, and then putting the evaporated material into a muffle furnace to roast at 550 ℃ for 2.5h to obtain a modified Y-type molecular sieve (the molecular sieve is also called zeolite) product, which is recorded as DZ 8. The physicochemical properties thereof are shown in Table 1.

After DZ8 is aged for 17h at 800 ℃, 1atm and 100% water vapor in a naked state, the relative crystallinity of the molecular sieve before and after the aging of DZ8 is analyzed by an XRD method, and the retention rate of the relative crystallinity after the aging is calculated, and the result is shown in Table 2.

Comparative example 9

This comparative example employed the conventional FCC catalyst of CN104560187a example 1, designated catalyst DC 9.

Test examples 1 to 4

The catalytic cracking reaction performance of the modified Y-type molecular sieves of examples 1-4 was tested.

The modified Y-type molecular sieves SZ 1-SZ 4 prepared in examples 1-4 are prepared into catalysts, and the serial numbers of the catalysts are as follows: SC 1-SC 4.

The preparation method of the catalyst comprises the following steps:

the modified Y-type molecular sieve, kaolin, water, the pseudo-boehmite adhesive and the alumina sol are formed into slurry according to a conventional preparation method of a catalytic cracking catalyst, and the slurry is sprayed and dried to prepare the microspherical catalyst, wherein the obtained catalyst contains 30 wt% of the modified Y-type molecular sieve, 42 wt% of the kaolin, 25 wt% of the pseudo-boehmite and 3 wt% of the alumina sol on a dry basis.

Evaluating the cracking performance of the catalyst for processing hydrogenated LCO, and evaluating the conditions as follows: the catalyst was first aged at 800 deg.C for 12h with 100% steam, then evaluated on an ACE (fixed fluidized bed) apparatus, the feed oil was SJZHLCO (hydrogenated LCO) (properties are shown in Table 3), and the reaction temperature was 500 deg.C. The results are shown in Table 4.

Wherein LCO effective conversion/% -100-diesel yield-dry gas yield-coke yield-heavy oil yield.

Comparative examples 1 to 9

The ultra-stable Y-type zeolite prepared by the method provided by comparative examples 1-8 and the conventional FCC catalyst DC9 of comparative example 9 were tested for catalytic cracking reaction performance.

Respectively mixing the ultrastable Y-type molecular sieves DZ 1-DZ 8 prepared in comparative examples 1-8 with pseudo-boehmite, kaolin, water and alumina sol according to the preparation method of the catalyst in test example 1, and spray-drying to prepare the microspherical catalyst, wherein the composition of each catalyst is the same as that in test example 1, and the catalyst numbers are as follows: DC 1-DC 8.

After aging the catalysts DC 1-DC 9 for 12h at 800 ℃ with 100% water vapor, the catalytic cracking reaction performance of the catalysts for processing hydrogenated LCO is evaluated on a small-sized fixed fluidized bed reactor (ACE), the evaluation method is shown in test example 1, the properties of raw materials for ACE experiments are shown in Table 3, and the results are respectively shown in Table 4. Wherein LCO effective conversion/% -100-diesel yield-dry gas yield-coke yield-heavy oil yield.

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 a B acid/L acid (a ratio of a strong B acid amount to an L acid amount) is higher, and has high crystallinity, particularly a higher crystallinity value when the rare earth content of the molecular sieve has a smaller unit cell constant, a high lattice collapse temperature, and high thermal stability.

TABLE 2

As can be seen from Table 2, the modified Y-type molecular sieve provided by the invention has a high relative crystallinity retention rate after being aged under severe conditions of 800 ℃ and 17 hours in an exposed molecular sieve sample, which indicates that the modified Y-type molecular sieve provided by the invention has high hydrothermal stability.

TABLE 3 Properties of hydrogenated LCO (SJZHLCO)

Item	Numerical value
		Carbon content/%)	88.91
Content of hydrogen/%)	11.01
		Density/(kg/m) at 20 DEG C³)	910.7
Mass spectral hydrocarbon mass composition/%)
		Alkane hydrocarbons	10.1
Total cycloalkanes	16.9
		Total monocyclic aromatic hydrocarbons	60.3
Total bicyclic aromatic hydrocarbons	11.5
		Tricyclic aromatic hydrocarbons	1.2
Total aromatic hydrocarbons	73
		Glue	0
Total weight of	100
		Nitrogen content/mg/L	0.9
Sulfur content/mg/L	49

TABLE 4

As can be seen from the results listed in table 4, the catalytic cracking catalyst prepared by using the molecular sieve provided by the present invention as an active component has significantly lower coke selectivity, higher LCO conversion rate, and significantly higher gasoline yield, and further, the yield of BTX (benzene + toluene + xylene) in gasoline is significantly increased, the propylene yield is high, and the propylene concentration in liquefied gas is high.

The preferred embodiments of the present disclosure have been described in detail above, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims

1. The modified Y-type molecular sieve is characterized in that on the basis of the dry weight of the modified Y-type molecular sieve, the modified Y-type molecular sieve contains 5-12 wt% of rare earth elements calculated by oxides, not more than 0.5 wt% of sodium oxide, 0.1-2.5 wt% of gallium oxide and 0.1-2.5 wt% of zirconium oxide; the total pore volume of the modified Y-type molecular sieve is 0.36-0.48 mL/g, and the pore volume of secondary pores with the pore diameter of 2-100 nm accounts for 20-38% of the total pore volume; the unit cell constant of the modified Y-type molecular sieve is 2.440-2.455 nm, and the lattice collapse temperature is not lower than 1060 ℃; the proportion of non-framework aluminum content of the modified Y-type molecular sieve in the total aluminum content is not higher than 10%, and the ratio of B acid content to L acid content in strong acid content of the modified Y-type molecular sieve is not lower than 3.0.

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

3. The modified Y-type molecular sieve of claim 1, wherein the specific surface area of the modified Y-type molecular sieve is 600-680 m²/g。

4. The modified Y-type molecular sieve 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; with n (SiO)₂)/n(Al₂O₃) And the framework silicon-aluminum ratio of the modified Y-type molecular sieve is 7-14.

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

6. The modified Y-type molecular sieve of claim 1, wherein the ratio of the amount of B acid to the amount of L acid in the strong acid amount of the modified Y-type molecular sieve is 3.2-5.6; the ratio of the B acid amount to the L acid amount in the strong acid amount of the modified Y-type molecular sieve is measured at 350 ℃ by adopting a pyridine adsorption infrared method.

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

8. The modified Y-type molecular sieve of claim 1, wherein the modified Y-type molecular sieve has a relative crystallinity retention of 38% or greater as measured by XRD after aging with 100% steam at 800 ℃ for 17 hours.

9. The modified Y-type molecular sieve of any one of claims 1 to 8, wherein the modified Y-type molecular sieve contains, in terms of oxide, 5.5 to 10 wt% of rare earth elements, 0.15 to 0.3 wt% of sodium oxide, 0.2 to 2 wt% of gallium oxide, and 0.5 to 2 wt% of zirconium oxide, based on the dry weight of the modified Y-type molecular sieve; the unit cell constant of the modified Y-type molecular sieve is 2.442-2.453 nm; with n (SiO)₂)/n(Al₂O₃) The framework silica-alumina ratio of the modified Y-type molecular sieve is 7.8-12.6; the rare earth element comprises La, Ce, Pr or Nd, or a combination of two or three or four thereof.

10. A process for preparing a modified Y-type molecular sieve according to any one of claims 1 to 9, comprising the steps of:

11. The method of claim 10, wherein the method of ion exchange reaction comprises: mixing NaY molecular sieve with water, adding rare earth salt and/or rare earth salt water solution under stirring to perform ion exchange reaction, and filtering and washing;

12. The process of claim 10 or 11, wherein the ion exchanged molecular sieve has a unit cell constant of 2.465 to 2.472nm, a rare earth content of 5.5 to 14 wt% calculated as oxide, and a sodium oxide content of 4 to 9 wt%.

13. The method of claim 10 or 11, wherein the rare earth salt is a rare earth chloride or a rare earth nitrate.

14. The method of claim 10, wherein the processing conditions of step (2) comprise: the first roasting is carried out for 5-6 h at 380-480 ℃ under 40-80% water vapor.

15. The method according to claim 10 or 14, wherein the molecular sieve modified by mild hydrothermal superstability has a unit cell constant of 2.450-2.462 nm, and the molecular sieve modified by mild hydrothermal superstability has a water content of not more than 1 wt%.

16. The method of claim 10, wherein in step (3), SiCl is used₄The weight ratio of the modified molecular sieve to the modified molecular sieve for moderating hydrothermal superstability is (0.1-0.7): 1, the temperature of the contact reaction is 200-650 ℃, and the reaction time is 10 min-5 h; the second washing method includes: washing with water until the pH value of a washing liquid is 2.5-5.0, the washing temperature is 30-60 ℃, and the weight ratio of the water consumption to the unwashed gas-phase ultra-stable modified molecular sieve is (6-15): 1.

17. the method according to claim 11, wherein the acid treatment conditions in step (4) include: the acid treatment temperature is 80-99 ℃, the acid treatment time is 1-4 h, the acid solution comprises organic acid and/or inorganic acid, and the weight ratio of the acid in the acid solution, the water in the acid solution and the gas-phase ultra-stable modified molecular sieve based on the dry weight is (0.001-0.15): (5-20): 1.

18. the method according to claim 10, wherein the acid treatment in the step (4) comprises: firstly, the gas-phase ultra-stable modified molecular sieve is in first contact with an inorganic acid solution, and then is in second contact with an organic acid solution;

19. the method of claim 17 or 18, wherein the organic acid is oxalic acid, malonic acid, succinic acid, methylsuccinic acid, malic acid, tartaric acid, citric acid, or salicylic acid, or a combination of two or three or four thereof; the inorganic acid is phosphoric acid, hydrochloric acid, nitric acid or sulfuric acid, or a combination of two or three or four of them.

20. The method of claim 10, wherein the contacting of step (5) comprises: uniformly mixing the molecular sieve after acid treatment with an aqueous solution containing a gallium salt and a zirconium salt, and then standing the mixture at 15-40 ℃ for 24-36 h, wherein the weight ratio of gallium in terms of oxides, zirconium in terms of oxides and the molecular sieve after acid treatment in terms of dry weight in the aqueous solution containing the gallium salt and the zirconium salt is (0.001-0.025): (0.001-0.025): 1, the weight ratio of water in the aqueous solution to the acid-treated molecular sieve on a dry basis is (2-3): 1.

21. the method of claim 10, wherein in step (5), the conditions of the second firing comprise: the roasting temperature is 450-600 ℃, and the roasting time is 2-5 h.