阅读说明：本技术 催化裂化催化剂及其制备方法和应用 (Catalytic cracking catalyst, preparation method and application thereof ) 是由 周灵萍 张蔚琳 陈振宇 袁帅 沙昊 姜秋桥 许明德 田辉平 于 2018-08-17 设计创作，主要内容包括：本公开涉及一种催化裂化催化剂及其制备方法和应用。该催化剂含有10～50重％的改性Y型分子筛、以氧化铝计10～40重％的氧化铝粘结剂和以干基计10～80重％的粘土；以改性Y型分子筛的干基重量为基准,改性Y型分子筛以氧化物计稀土元素的含量为5～12重％,氧化钠的含量不超过0.5重％,活性元素氧化物的含量为0.1～5重％,活性元素为镓和/或硼；改性Y型分子筛的总孔体积为0.36～0.48mL/g,孔径为2～100nm的二级孔的孔体积占总孔体积的比例为20～38％；晶胞常数为2.440～2.455nm,晶格崩塌温度不低于1060℃；改性Y型分子筛的非骨架铝含量占总铝含量的比例不高于10％,改性Y型分子筛的强酸量中B酸量与L酸量的比值不低于3.0。该催化剂用于加工加氢LCO时LCO转化效率高,焦炭选择性低,汽油收率高且富含BTX。(The present disclosure relates to a catalytic cracking catalyst, a preparation method and an application thereof. The catalyst contains 10-50 wt% of modified Y-type molecular sieve, 10-40 wt% of alumina binder calculated by alumina and 10-80 wt% of clay calculated by dry basis; 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 in terms of oxides, the content of sodium oxide is not more than 0.5 wt%, the content of active element oxides is 0.1-5 wt%, and the active elements are gallium and/or boron; 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 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. When the catalyst is used for processing hydrogenated LCO, the LCO conversion efficiency is high, the coke selectivity is low, the gasoline yield is high, and the BTX is rich.)

1. The catalytic cracking catalyst is characterized by comprising 10-50 wt% of modified Y-type molecular sieve, 10-40 wt% of alumina binder and 10-80 wt% of clay on a dry basis, wherein the modified Y-type molecular sieve is based on the dry basis weight of the catalyst;

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, the content of sodium oxide is not more than 0.5 wt%, the content of active element oxides is 0.1-5 wt%, and the active elements are gallium and/or boron; 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 catalytic cracking catalyst of claim 1, wherein the modified Y-type molecular sieve has a pore volume of secondary pores having a pore diameter of 2 to 100nm in a proportion of 28 to 37% by volume of the total pores.

3. The catalytic cracking catalyst of claim 1, wherein the modified Y-type molecular sieve has a specific surface area of 600 to 680m²/g。

4. The catalytic cracking catalyst of claim 1, wherein the non-framework aluminum content of the modified Y-type molecular sieve accounts for 5-9.5% of the total aluminum content; with n (SiO)₂)/n(Al₂O₃) And the framework silicon-aluminum ratio of the modified Y-type molecular sieve is 7-14.

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

6. The catalytic cracking catalyst of claim 1, wherein the ratio of the amount of B acid to the amount of L acid in the strong acid amount of the modified Y-type molecular sieve is 3.2-6; 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 catalytic cracking catalyst of claim 1, wherein the modified Y-type molecular sieve has a relative crystallinity of 70 to 80%.

8. The catalytic cracking catalyst of claim 1, wherein 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 ℃ for 17 hours.

9. The catalytic cracking catalyst of any one of claims 1 to 8, wherein the modified Y-type molecular sieve is based on oxygen on a dry weight basisThe content of the rare earth element is 5.5-10 wt% and the content of the sodium oxide is 0.15-0.3 wt% in terms of the compound; 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 of them;

the active element is gallium, the content of gallium oxide is 0.1-3 wt%, or the active element is boron, and the content of boron oxide is 0.5-5 wt%; or the active elements are gallium and boron, and the total content of gallium oxide and boron oxide is 0.5-5 wt%.

10. The catalytic cracking catalyst of claim 1, wherein the clay is kaolin, halloysite, montmorillonite, diatomaceous earth, halloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite, or bentonite, or a combination of two or three or four thereof; the alumina binder is alumina, hydrated alumina or alumina sol, or a combination of two or three or four of them.

11. A process for preparing a catalytic cracking catalyst according to any of claims 1 to 10, characterized in that it comprises: preparing a modified Y-type molecular sieve, forming slurry comprising the modified Y-type molecular sieve, an alumina binder, clay and water, and spray-drying to obtain the catalytic cracking catalyst;

wherein, the preparation of the modified Y-type molecular sieve comprises the following steps:

(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 vol% of steam 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) contacting the molecular sieve after acid treatment with a solution containing active elements, and drying and carrying out second roasting to obtain the modified Y-type molecular sieve; the active element is gallium and/or boron.

12. The method of claim 11, 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;

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).

13. The process of claim 11 or 12, 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%.

14. The method of claim 11 or 12, wherein the rare earth salt is a rare earth chloride or a rare earth nitrate.

15. The method of claim 11, wherein the processing conditions of step (2) comprise: the first roasting is carried out for 5-6 h at 380-480 ℃ and under 40-80 vol% of water vapor.

16. The method according to claim 11 or 15, 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.%.

17. The method of claim 11, wherein in step (3), SiCl₄The 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.

18. 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.

19. the method according to claim 11, 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;

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.

20. the method of claim 18 or 19, 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.

21. The method according to claim 11, wherein the solution containing the active element is an aqueous solution of a gallium salt and/or an aqueous solution of a boron compound;

the method for contacting the acid-treated molecular sieve with the solution containing the active element comprises the following steps: uniformly mixing the molecular sieve after acid treatment with a gallium salt aqueous solution, and then standing for 24-36 h at 15-40 ℃, wherein the weight ratio of gallium in the gallium salt aqueous solution, calculated as oxides, water in the gallium salt aqueous solution and the molecular sieve after acid treatment on a dry basis is (0.001-0.03): (2-3): 1; or may comprise, in combination with the above-mentioned,

heating the acid-treated molecular sieve to 60-99 ℃, and then contacting and mixing the acid-treated molecular sieve with a boron compound in an aqueous solution for 1-2 h, wherein the weight ratio of boron in the aqueous solution, water in the aqueous solution and the acid-treated molecular sieve is (0.005-0.05): (2.5-5): 1, the boron compound is selected from boric acid, a borate, a metaborate or a polyborate, or a combination comprising two or three or four of them; or may comprise, in combination with the above-mentioned,

heating the molecular sieve subjected to acid treatment to 85-95 ℃, then contacting and mixing the molecular sieve with a boron compound in a first aqueous solution for 1-2 h, filtering, uniformly mixing the obtained molecular sieve material with a second aqueous solution containing gallium salt, and standing for 24-36 h at 15-40 ℃; the weight ratio of boron in the first aqueous solution calculated as oxide, water in the first aqueous solution and the acid-treated molecular sieve calculated as dry weight is (0.005-0.03): (2.5-5): 1, the weight ratio of the gallium in the second aqueous solution calculated by oxide, the water in the second aqueous solution and the molecular sieve material calculated by dry weight is (0.001-0.02): (2-3): 1.

22. the method of claim 11, wherein in step (5), the conditions of the second firing comprise: the roasting temperature is 350-600 ℃, and the roasting time is 1-5 h.

23. Use of the catalytic cracking catalyst of any one of claims 1 to 10 in catalytic cracking reactions of hydrocarbon feedstocks.

24. A catalytic cracking process for processing hydrogenated LCO, comprising the step of contacting hydrogenated LCO with the catalyst of any one of claims 1 to 10 under catalytic cracking conditions; wherein the catalytic cracking conditions comprise: the reaction temperature is 500-610 ℃, and the weight hourly space velocity is 2-16 h^-1The agent-oil ratio is 3-10, and the agent-oil ratio is a weight ratio.

Technical Field

The present disclosure relates to a catalytic cracking catalyst, a preparation method and an application 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 2-20 hours at the temperature of 115-250 ℃ higher than the boiling point, the volume of the obtained Y-shaped molecular sieve mesopores can reach 0.2-0.6 ml/g, but the crystallinity and the surface area are obviously reduced.

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

CN1388064 discloses a process for preparing 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 mixing a NaY molecular sieve with a catalyst containing 6-94 wt%Contacting the ammonium salt aqueous solution of the ammonium salt twice or more according to the weight ratio of the ammonium salt to the molecular sieve of 0.1-24 under the conditions of normal pressure and the temperature of more than 90 ℃ to not more than the boiling point temperature of the ammonium salt aqueous solution to ensure that 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

The purpose of the present disclosure is to provide a catalytic cracking catalyst, which has higher LCO conversion efficiency, better coke selectivity and higher yield of gasoline rich in aromatics, and a preparation method and application thereof.

In order to achieve the above object, the first aspect of the present disclosure provides a catalytic cracking catalyst comprising 10 to 50 wt% of a modified Y-type molecular sieve, 10 to 40 wt% of an alumina binder, and 10 to 80 wt% of clay, on a dry basis, based on the dry weight of the catalyst;

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, the content of sodium oxide is not more than 0.5 wt%, the content of active element oxides is 0.1-5 wt%, and the active elements are gallium and/or boron; 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 28-37% 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 3.2-6; 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%; after aging for 17h at 800 ℃ by 100% steam, the retention rate of the relative crystallinity of the modified Y-type molecular sieve measured by XRD is more than 38%.

Optionally, the modified Y-type molecular sieve contains 5.5-10 wt% of rare earth elements and 0.15-0.3 wt% of sodium oxide calculated by oxides 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 of them;

the active element is gallium, the content of gallium oxide is 0.1-3 wt%, or the active element is boron, and the content of boron oxide is 0.5-5 wt%; or the active elements are gallium and boron, and the total content of gallium oxide and boron oxide is 0.5-5 wt%.

Optionally, the clay is kaolin, halloysite, montmorillonite, diatomaceous earth, halloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite, or bentonite, or a combination of two or three or four thereof; the alumina binder is selected from alumina, hydrated alumina or alumina sol, or a combination of two or three or four of them.

A second aspect of the present disclosure provides a process for preparing a catalytic cracking catalyst according to the first aspect of the present disclosure, the process comprising: preparing a modified Y-type molecular sieve, forming slurry comprising the modified Y-type molecular sieve, an alumina binder, clay and water, and spray-drying to obtain the catalytic cracking catalyst;

wherein, the preparation of the modified Y-type molecular sieve comprises the following steps:

(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 vol% of steam 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) contacting the molecular sieve after acid treatment with a solution containing active elements, and drying and carrying out second roasting to obtain the modified Y-type molecular sieve; the active element is gallium and/or boron.

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 a rare earth chloride or a rare earth nitrate.

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

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 solution containing the active element is an aqueous solution of a gallium salt and/or an aqueous solution of a boron compound;

the method for contacting the acid-treated molecular sieve with the solution containing the active element comprises the following steps: uniformly mixing the molecular sieve after acid treatment with a gallium salt aqueous solution, and then standing for 24-36 h at 15-40 ℃, wherein the weight ratio of gallium in the gallium salt aqueous solution, calculated as oxides, water in the gallium salt aqueous solution and the molecular sieve after acid treatment on a dry basis is (0.001-0.03): (2-3): 1; or may comprise, in combination with the above-mentioned,

heating the acid-treated molecular sieve to 60-99 ℃, and then contacting and mixing the acid-treated molecular sieve with a boron compound in an aqueous solution for 1-2 h, wherein the weight ratio of boron in the aqueous solution, water in the aqueous solution and the acid-treated molecular sieve is (0.005-0.05): (2.5-5): 1, the boron compound is selected from boric acid, a borate, a metaborate or a polyborate, or a combination comprising two or three or four of them; or may comprise, in combination with the above-mentioned,

heating the molecular sieve subjected to acid treatment to 85-95 ℃, then contacting and mixing the molecular sieve with a boron compound in a first aqueous solution for 1-2 h, filtering, uniformly mixing the obtained molecular sieve material with a second aqueous solution containing gallium salt, and standing for 24-36 h at 15-40 ℃; the weight ratio of boron in the first aqueous solution calculated as oxide, water in the first aqueous solution and the acid-treated molecular sieve calculated as dry weight is (0.005-0.03): (2.5-5): 1, the weight ratio of the gallium in the second aqueous solution calculated by oxide, the water in the second aqueous solution and the molecular sieve material calculated by dry weight is (0.001-0.02): (2-3): 1.

alternatively, in the step (5), the conditions of the second firing include: the roasting temperature is 350-600 ℃, and the roasting time is 1-5 h.

A third aspect of the present disclosure provides the use of a catalytic cracking catalyst according to the first aspect of the present disclosure in the catalytic cracking reaction of a hydrocarbon feedstock.

A fourth aspect of the present disclosure provides a catalytic cracking process for processing hydrogenated LCO, comprising the step of contacting, under catalytic cracking conditions, the hydrogenated LCO with a catalyst as described in the first aspect of the present disclosure; wherein the catalysisThe cracking conditions include: the reaction temperature is 500-610 ℃, and the weight hourly space velocity is 2-16 h^-1The agent-oil ratio is 3-10, and the agent-oil ratio is a weight ratio.

According to the technical scheme, the method for preparing the catalytic cracking catalyst provided by the disclosure can be used for preparing the high-silicon Y-type molecular sieve rich in the secondary pore structure and having high crystallinity, high thermal stability and high hydrothermal stability by performing rare earth exchange, hydrothermal hyperstable treatment and gas-phase hyperstable treatment on the Y-type molecular sieve, cleaning pore channels of the molecular sieve by combining acid treatment and performing impregnation modification by adopting active elements, wherein the molecular sieve has high crystallinity, uniform aluminum distribution, less non-framework aluminum content and smooth pore channels of the secondary pores under the condition of greatly improving the hyperstable degree, and has a high specific surface area under the condition of having high secondary pores, and the catalytic cracking catalyst prepared by adopting the modified Y-type molecular sieve has high reactivity. The catalytic cracking catalyst of the present disclosure having the above-described modified Y-type molecular sieve as an active component is useful for processing hydrogenated LCO while having high LCO conversion efficiency (e.g., high LCO effective conversion) and lower coke selectivity, and with higher and BTX-rich gasoline 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 present disclosure provides a catalytic cracking catalyst, which contains 10 to 50 wt% of a modified Y-type molecular sieve, 10 to 40 wt% of an alumina binder, and 10 to 80 wt% of clay, on a dry basis, based on the dry basis weight of the catalyst;

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, the content of sodium oxide is not more than 0.5 wt%, the content of active element oxides is 0.1-5 wt%, and the active elements are gallium and/or boron; 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 catalytic cracking catalyst disclosed by the invention contains a modified Y-shaped molecular sieve with high crystallinity, high thermal stability and high hydrothermal stability, the modified Y-shaped molecular sieve is uniform in aluminum distribution, low in non-framework aluminum content, smooth in secondary pore channels, and high in specific surface area under the condition of having high secondary pores, and the catalytic cracking catalyst has high LCO conversion efficiency when being used for processing hydrogenated LCO, has low coke selectivity, and has high gasoline yield rich in BTX.

In the catalytic cracking catalyst provided by the disclosure, the modified Y-type molecular sieve is a rare earth-containing ultrastable Y-type molecular sieve rich in secondary pores, and a secondary pore distribution curve with the pore diameter of 2 nm-100 nm in the molecular sieve is in double-variable pore distribution, wherein the most variable pore diameter of the secondary pores with smaller pore diameters is 2 nm-5 nm, and the most variable pore diameter of the secondary pores with larger pore diameters is 8 nm-20 nm, preferably 8 nm-18 nm. Preferably, the pore volume of the secondary pores with the pore diameter of 2-100 nm accounts for 28-37% or 25-37% of the total pore volume.

In the catalytic cracking catalyst provided by the disclosure, the modified Y-type molecular sieve 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%, based on 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.

In the catalytic cracking catalyst provided by the present disclosure, the modified Y-type molecular sieve contains active elements gallium and/or boron, and the content of the active element oxide may be 0.1 to 5 wt% based on the dry weight of the molecular sieve, wherein preferably, in one embodiment, the active element is gallium, and the content of gallium oxide may be 0.1 to 3 wt%, and more preferably 0.5 to 2.5 wt%; in one embodiment, the active element is boron, and the content of boron oxide may be 0.5 to 5 wt%, and more preferably 1 to 4 wt%; in one embodiment, the active elements are gallium and boron, the total content of gallium oxide and boron oxide is 0.5 to 5 wt%, preferably 1 to 3 wt%, the content of gallium oxide may be 0.1 to 2.5 wt%, and the content of boron oxide may be 0.5 to 4 wt%. Within the preferable content range, the conversion efficiency of the modified Y-type molecular sieve for catalyzing LCO is higher, the coke selectivity is lower, and the gasoline rich in aromatic hydrocarbon can be obtained more favorably.

In the catalytic cracking catalyst provided by the present disclosure, the modified Y-type molecular sieve may contain a small amount of sodium, and the content 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.

In the catalytic cracking catalyst provided by the disclosure, the rare earth element, the sodium oxide and the active element in the modified Y-type molecular sieve can be respectively measured by adopting an X-ray fluorescence spectrometry method.

In the catalytic cracking catalyst provided by the disclosure, the pore structure of the modified Y-type molecular sieve can be further optimized to obtain more appropriate 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 15-21%, 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 RIPP 151-90 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(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.

In the catalytic cracking catalyst provided by the present disclosure, the unit cell constant of the modified Y-type molecular sieve is further preferably 2.440 to 2.455nm, for example, 2.442 to 2.453nm or 2.442 to 2.451 nm. The lattice collapse temperature of the modified Y-type molecular sieve is preferably not lower than 1060 ℃, for example, 1060-1085 ℃, more preferably not lower than 1064 ℃, for example, 1064-1081 ℃.

In the catalytic cracking catalyst provided by the present disclosure, the relative crystallinity of the modified Y-type molecular sieve may be not less than 70%, for example, 70 to 80%, preferably not less than 71%, for example, 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. It is composed ofIn (d), the relative crystallinity retention rate ═ relative crystallinity of aged sample/relative crystallinity of fresh sample × 100%.

In the catalytic cracking catalyst provided by the disclosure, 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.

In the catalytic cracking catalyst provided by 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 B acid to the amount of L acid in the strong acid amount of the modified Y-type molecular sieve is preferably 3.2 to 6, and further, when the active element is gallium, 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 preferably 3.2 to 5.6, for example, 3.3 to 5.5; when the active element is boron, 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 not less than 3.5, preferably 3.5-6, such as 3.6-5.5 or 3.5-5 or 3.5-4.6 or 3.8-5.6; when the active elements are gallium and boron, 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 3.5-5.5, for example 3.8-5.3. 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 a specific embodiment of the present disclosure, based on the dry weight of the modified Y-type molecular sieve, the content of the rare earth element of the modified Y-type molecular sieve calculated by oxide may be 5.5 to 10 wt%, and the content of sodium oxide may be 0.15 to 0.3 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) The framework silicon-aluminum ratio of the modified Y-type molecular sieve can be 7.8-12.6; the active element is gallium, and the content of gallium oxide is 0.1-3 wt%(ii) a Or the active element is boron, and the content of boron oxide is 0.5-5 wt%; the active elements are gallium and boron, or the total content of gallium oxide and boron oxide is 0.1-5 wt%.

In the catalytic cracking catalyst provided by 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 of them, and may further include other rare earth elements besides La, Ce, Pr, and Nd.

The catalytic cracking catalyst provided by the present disclosure may further contain other molecular sieves than the modified Y-type molecular sieve, such as 0 to 40 wt%, such as 0 to 30 wt% or 1 to 20 wt% based on the weight of the catalytic cracking catalyst, on a dry basis, the other molecular sieves are selected from the molecular sieves used in the catalytic cracking catalyst, such as zeolite with MFI structure, zeolite Beta, other Y-type zeolite or non-zeolite molecular sieve, or a combination comprising two or three or four thereof, preferably, the other Y-type zeolite is not more than 40 wt%, such as 1 to 40 wt% or 0 to 20 wt% based on a dry basis, the other Y-type zeolite, such as REY, REHY, DASY, SOY or PSRY, or a combination comprising two or three or four thereof, the MFI-structure zeolite, such as HZSM-5, ZRP or ZRP, or a combination comprising two or three or four thereof, the Beta zeolite, such as H β, the non-zeolite, such as aluminum molecular sieve (silicoaluminophosphate molecular sieve) or a silicoaluminophosphate molecular sieve (SAPO molecular sieve).

In the catalytic cracking catalyst for the high-yield aromatic-hydrocarbon-rich gasoline provided by the disclosure, the content of the modified Y-type molecular sieve is 10-50 wt%, preferably 15-45 wt%, for example 25-40 wt% on a dry basis.

In the catalytic cracking catalyst for high yield of aromatic-rich gasoline provided by the present disclosure, the clay is selected from one or more of clays used as a component of a cracking catalyst, such as kaolin, halloysite, montmorillonite, diatomaceous earth, halloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite, or bentonite, or a combination comprising two or three or four of them. These clays are well known to those of ordinary skill in the art. Preferably, the content of the clay in the catalytic cracking catalyst of the present disclosure is 20 to 55 wt% or 30 to 50 wt% on a dry basis.

The present invention provides a catalytic cracking catalyst for the high yield of aromatic hydrocarbon-rich gasoline, wherein the content of the alumina binder is 10-40 wt%, for example 20-35 wt%, calculated on alumina, the alumina binder is selected from one or more of various forms of alumina, hydrated alumina and alumina sol commonly used in cracking catalysts, for example, selected from gamma-alumina, η -alumina, theta-alumina, chi-alumina, pseudoboehmite (pseudobomoemeilite), Boehmite (boemite), Gibbsite (Gibbsite), Bayerite (bayer) or alumina sol, or a combination comprising two or three or four of them, preferably the pseudoboehmite and the alumina sol, for example, the catalytic cracking catalyst contains 2-15 wt%, preferably 3-10 wt%, calculated on alumina, and 10-30 wt%, preferably 15-25 wt%, calculated on alumina, of pseudoboehmite.

The catalyst of the present disclosure can be prepared by the methods disclosed in patents CN1098130A and CN 1362472A. Typically comprising the steps of forming a slurry comprising the modified Y-type molecular sieve, a binder, clay and water, spray drying, optionally washing and drying. Spray drying, washing, drying are prior art, and the disclosure has no special requirements.

A second aspect of the present disclosure provides a process for preparing a catalytic cracking catalyst according to the first aspect of the present disclosure, the process comprising: preparing a modified Y-type molecular sieve, forming slurry comprising the modified Y-type molecular sieve, an alumina binder, clay and water, and spray-drying to obtain the catalytic cracking catalyst;

wherein, the preparation of the modified Y-type molecular sieve comprises the following steps:

(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 vol% of steam 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) contacting the molecular sieve after acid treatment with a solution containing active elements, and drying and carrying out second roasting to obtain the modified Y-type molecular sieve; the active element is gallium and/or boron.

The preparation method provided by the disclosure can be used for preparing the catalytic cracking catalyst rich in aromatic gasoline in high yield, the catalytic cracking catalyst contains the high-silicon Y-shaped molecular sieve rich in secondary pores and having high crystallinity, high thermal stability and high hydrothermal stability, and the catalytic cracking catalyst is used for processing hydrogenated LCO and has high LCO conversion efficiency, lower coke selectivity and higher yield of the aromatic gasoline.

In the preparation method of the catalytic cracking catalyst 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 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 may comprise slurrying the NaY molecular sieve and water, and adding to the slurry a rare earth salt and/or an aqueous solution of a rare earth salt, the rare earth salt being a solution of a rare earth salt, the rare earth salt preferably being a rare earth chloride and/or a 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 catalytic cracking catalyst, in the step (2), the Y-type molecular sieve containing rare earth and having a conventional unit cell size 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 30-95 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 reacting with SiCl₄The 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 catalytic cracking catalyst provided by the present disclosure, the contact reaction conditions of the step (3) can be changed within a wide range, and in order to further promote the gas phase ultra-stable treatment effect, preferably, SiCl₄The 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 (0.2-0.6): 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 filtration 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⁺Is isosolubleA by-product, the washing method may 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 catalytic cracking catalyst provided by the disclosure, 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 channel cleaning modification to ensure that secondary pores are unblocked, which is called pore channel cleaning for short. In one embodiment of the disclosure, the gas phase ultrastable modified molecular sieve obtained in step (3) is contacted with an acid solution for reaction, the gas phase ultrastable modified molecular sieve, that is, the gas phase ultrastable modified molecular sieve is mixed with the acid solution, and reacted for a period of time, then the reacted molecular sieve is separated from the acid solution, for example, filtered and separated, and then optionally washed and optionally dried, so as to obtain the modified Y-type molecular sieve provided by the invention, wherein the gas phase ultrastable modified molecular sieve is contacted with the acid solution, the acid treatment temperature can be 60-100 ℃, preferably 80-99 ℃, further preferably 88-98 ℃, and the acid treatment time can be 1-4 hours, preferably 1-3 hours; 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 of the catalytic cracking catalyst provided by the present disclosure, the molecular sieve may be contacted with a solution containing an active element, and exchange and/or impregnation treatment is performed to load the active element on the modified Y-type molecular sieve, and in order to facilitate improvement of the exchange and/or impregnation treatment effect, the solution containing the active element is preferably an aqueous solution of a gallium salt or an aqueous solution of a boron compound or an aqueous solution containing a gallium salt and a boron compound, or a combination of both of them; the contact with the active element solution can be carried out once or for multiple times so as to introduce the active element with required quantity; for example:

in one embodiment, in step (5), the acid-treated molecular sieve is contacted with an aqueous solution of gallium salt, that is, the solution containing the active element is an aqueous solution of gallium salt, and the contacting method may include: and uniformly mixing the molecular sieve after acid treatment with the aqueous solution of the gallium salt, and standing. For example, the acid-treated molecular sieve may be added to Ga (NO) under stirring₃)₃The solution of (2) is dipped with the gallium component, stirred uniformly and then kept stand for 24-36 h at 15-40 ℃, preferably kept stand at room temperature. Then the molecular sieve containing the acid treated molecular sieve is mixed with Ga (NO)₃)₃And stirring the slurry for 20min to uniformly mix the slurry, drying the slurry and performing second roasting, wherein the drying can be any one of drying methods, such as flash drying, drying and air flow drying, in one mode, the drying method is, for example, transferring the slurry into a rotary evaporator to perform 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 at 480-580 ℃ for 2.2-4.5 h.

Wherein the aqueous solution of gallium salt may be Ga (NO)₃)₃Aqueous solution, Ga₂(SO₄)₃Aqueous solutions or GaCl₃Aqueous solution, or a combination of two or three thereof, preferably Ga (NO)₃)₃An aqueous solution. The weight ratio of water in the aqueous solution of gallium salt, gallium salt and gallium salt calculated as oxides to the molecular sieve after acid treatment on a dry basis in the aqueous solution of gallium salt may be (0.001-0.03): (2-3): 1, preferably (0.005 to 0.025): (2.2-2.6): 1.

in another embodiment, in step (5), the acid-treated molecular sieve is contacted with an aqueous solution of a boron compound, that is, the solution containing the active element is an aqueous solution of a boron compound, and the contacting method may include: heating the acid-treated molecular sieve to 60-99 ℃, then contacting and mixing the acid-treated molecular sieve with a boron compound in an aqueous solution for 1-2 h, preferably heating the acid-treated molecular sieve to 85-95 ℃, then contacting and mixing the acid-treated molecular sieve with the boron compound in the aqueous solution for 1-1.5 h, for example, adding the acid-treated molecular sieve into an exchange tank, mixing the acid-treated molecular sieve with water to form slurry, then heating the molecular sieve slurry to 85-95 ℃, then adding the boron compound, stirring and mixing for 1h, then filtering, drying the filtered sample, and performing second roasting, wherein the drying can be any drying method, such as flash drying, drying and air flow drying, in one mode, for example, drying at 120-140 ℃ for 5-10 h, then performing second roasting, and the second roasting condition is preferably roasting at 350-600 ℃ for 1-4 h; the boron compound may comprise a compound containing a positive boron ion, for example selected from boric acid, a borate, a metaborate or a polyborate, or from a combination of two or three or four thereof;

wherein the liquid-solid ratio in the molecular sieve slurry, namely the weight ratio of water to the molecular sieve, can be (2.5-5): 1, preferably (2.8-4.5): 100, adding boron compound in an amount of B₂O₃Preferably B₂O₃: the molecular sieve is (0.5-4.5): 100, preferably (0.8-4.2): 100.

in a third embodiment, in step (5), the acid-treated molecular sieve is contacted with an aqueous solution of gallium salt and an aqueous solution of boron compound, respectively, that is, the solution containing active elements is an aqueous solution of gallium salt and an aqueous solution of boron compound, and the contacting method may include: heating the molecular sieve after acid treatment to 85-95 ℃, then contacting and mixing the molecular sieve with a boron compound in a first aqueous solution for 1-2 h, filtering, uniformly mixing the molecular sieve material with a second aqueous solution containing gallium salt, and standing for 24-36 h at 15-40 ℃. For example, the acid-treated molecular sieve can be added into an exchange tank to be mixed with water to form slurry, then the temperature of the molecular sieve slurry is raised to 85-95 ℃, then the boron compound is added, namely the molecular sieve slurry is contacted with the boron compound in the first aqueous solution, the mixture is stirred and mixed for 1 hour and then filtered, and then the filter cake is added into Ga (NO) while being stirred₃)₃Is impregnated with a gallium component containing Ga (NO) in a solution (i.e., a second aqueous solution)₃)₃And stirring the slurry for 20min to uniformly mix the slurry, drying the slurry and performing second roasting, wherein the drying can be any one of drying methods, such as flash drying, drying and air flow drying, in one mode, the drying method is, for example, transferring the slurry into a rotary evaporator to perform 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 at 480-580 ℃ for 2.2-4.5 h.

Wherein the weight ratio of boron in the first aqueous solution, water in the first aqueous solution and the acid-treated molecular sieve on a dry basis may be (0.005-0.03): (2.5-5): the weight ratio of the gallium in the second aqueous solution calculated by oxide, the water in the second aqueous solution and the molecular sieve material calculated by dry weight can be (0.001-0.02): (2-3): 1.

in one embodiment of the present disclosure, preparing the modified Y-type molecular sieve may comprise 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, performing contact reaction at the temperature of 200-650 ℃ for 10min to 5h, optionally washing and optionally filtering to obtain the 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)₃Is impregnated with a gallium component and the acid-treated molecular sieve is mixed with a solution containing Ga (NO)₃)₃The solution of (A) is stirred uniformly and then is allowed to stand at room temperature, wherein Ga (NO)₃)₃Ga (NO) contained in the solution of (1)₃)₃In an amount of Ga₂O₃The weight ratio of the molecular sieve to the molecular sieve after acid treatment is 0.1-3 wt%, and Ga (NO)₃)₃The amount of water added to the solution is 1 (2-3): 1 on dry basis) after acid treatment, the soaking time is 24 hours, and then the solution containing the modified Y molecular sieve and Ga (NO)₃)₃And stirring the 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.

In another embodiment of the present disclosure, preparing the modified Y-type molecular sieve may comprise 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 hours at the temperature of 350-480 ℃ in the atmosphere containing 30-90 vol% of water vapor, and drying to obtain a modified molecular sieve with the water content lower than 1 wt% and through mild hydrothermal superstability; the unit cell constant of the molecular sieve for moderating the hydrothermal superstable modification is 2.450 nm-2.462 nm;

(3) mixing molecular sieve sample modified by moderating 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 Y-type 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 molecular sieve on a dry basis is (0.02-0.10): 1, the weight ratio of the inorganic acid with the medium strength or more to the molecular sieve based on a dry basis is (0.01-0.05): 1, the weight ratio of water to the molecular sieve is (5-20): 1.

(5) adding the acid-treated molecular sieve obtained in the step (4) into an exchange tank, and adding chemical water to ensure that the liquid-solid ratio in the molecular sieve slurry, namely the weight ratio of water to the molecular sieve, can be (2.5-5): 1, heating the molecular sieve slurry to 85-95 ℃, and then adding boric acid, wherein the amount of the boric acid added is B₂O₃Is counted as B₂O₃: molecular sieve (0.5-4.5): 100,stirring for 1h, filtering, drying the filtered sample at 130 ℃ for 5h, and then roasting at 350-600 ℃ for 1-4 h.

In a third embodiment of the present disclosure, a method of preparing a modified Y-type molecular sieve may comprise 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 hours at the temperature of 350-480 ℃ in the atmosphere containing 30-90 vol% of water vapor, and drying to obtain a modified molecular sieve with the water content lower than 1 wt% and through mild hydrothermal superstability; the unit cell constant of the molecular sieve for moderating the hydrothermal superstable modification is 2.450 nm-2.462 nm;

(3) mixing molecular sieve sample modified by moderating 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 Y-type 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 molecular sieve on a dry basis is (0.02-0.10): 1, the weight ratio of the inorganic acid with the medium strength or more to the molecular sieve based on a dry basis is (0.01-0.05): 1, the weight ratio of water to the molecular sieve is (5-20): 1.

(5) adding the acid-treated molecular sieve obtained in the step (4) into an exchange tank, and adding chemical water to ensure that the liquid-solid ratio in the molecular sieve slurry, namely the weight ratio of water to the molecular sieve, can be (2.5-5): 1, heating the molecular sieve slurry to 85-95 ℃, and then adding boric acid, wherein the amount of the boric acid added is B₂O₃Is counted as B₂O₃: stirring the gas-phase super-stable modified molecular sieve (0.5-3): 100 for 1h, filtering, and adding the filter cake into Ga (NO) while stirring₃)₃The solution of (a) is impregnated with a gallium component, and the solution is stirred uniformly and then allowed to stand at room temperature, wherein Ga (NO)₃)₃Ga (NO) contained in the solution of (1)₃)₃In an amount of Ga₂O₃The weight ratio of the molecular sieve to the molecular sieve is 0.1-2 wt%, and Ga (NO)₃)₃The weight ratio of the water added in the solution to the molecular sieve is as follows: water: and (3) soaking the molecular sieve (dry basis): 1 for 24 hours, then stirring the slurry for 20min to uniformly mix the slurry, transferring the slurry into a rotary evaporator to carry out water bath heating and rotary evaporation to dryness, and then roasting the evaporated material in a muffle furnace at 450-600 ℃ for 2-5 hours to obtain the modified Y molecular sieve.

In the preparation method of the catalytic cracking catalyst provided by the disclosure, spray drying, washing and drying are the prior art, and the method has no special requirements.

In the preparation method of the catalytic cracking catalyst provided by the present disclosure, the amount of the modified Y-type molecular sieve may be conventional in the art, and preferably, the content of the modified Y-type molecular sieve in the prepared catalyst on a dry basis may be 10 to 50 wt%, preferably 15 to 45 wt%, for example, 25 to 40 wt%.

In the preparation method provided by the present disclosure, the clay may be selected from one or more of clays used as cracking catalyst components, such as one or more of kaolin, halloysite, montmorillonite, diatomite, halloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite, and bentonite. These clays are well known to those of ordinary skill in the art. The amount of the clay used may be conventional in the art, and preferably, the amount of the clay in the catalytic cracking catalyst of the present disclosure may be 20 to 55 wt% or 30 to 50 wt% on a dry basis.

In the preparation method provided by the disclosure, the alumina binder can be selected from one or more of alumina, hydrated alumina and alumina sol in various forms commonly used in cracking catalysts, for example, one or more of gamma-alumina, η -alumina, theta-alumina, chi-alumina, pseudoboehmite (pseudoboehmite), diaspore (Boehmite), Gibbsite (Gibbsite), Bayerite (bayer) or alumina sol, preferably pseudoboehmite and/or alumina sol, the alumina binder can be used in an amount conventional in the art, preferably, the alumina binder content in the catalytic cracking catalyst of the disclosure is 10 to 40 wt%, for example, 20 to 35 wt%, on a dry basis.

A third aspect of the present disclosure provides the use of a catalytic cracking catalyst according to the first aspect of the present disclosure in the catalytic cracking reaction of a hydrocarbon feedstock. In one embodiment, the catalytic cracking catalyst of the present disclosure may be used in a catalytic cracking reaction for processing hydrogenated LCO.

A fourth aspect of the present disclosure is a catalytic cracking process for processing hydrogenated LCO, comprising the step of contacting the hydrogenated LCO with the catalyst described above under catalytic cracking conditions; wherein the catalytic cracking conditions may comprise: the reaction temperature is 500-610 ℃, and the weight hourly space velocity is 2-16 h^-1The agent-oil ratio is 3-10, and the agent-oil ratio is a weight ratio.

In one embodiment, the hydrogenated LCO may have the following properties: density (20 ℃): 0.850-0.920 g/cm³And H content: 10.5 to 12 wt%, S content<50 μ g/g, N content<10 μ g/g, total aromatic content: 70-85 wt% and polycyclic aromatic hydrocarbon content less than or equal to 15 wt%.

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 and the gallium nitrate are chemically pure reagents produced by 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: self-supporting pressing the sampleAnd the sheet is arranged in an in-situ cell of the infrared spectrometer and sealed. 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 sieve

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

In each of the comparative examples and examples, the secondary pore volume was determined as follows: the total pore volume of the molecular sieve was determined from the adsorption isotherm according to RIPP 151-90 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.