阅读说明：本技术 一种催化裂化催化剂 (Catalytic cracking catalyst ) 是由 袁帅 周灵萍 田辉平 张蔚琳 沙昊 陈振宇 于 2018-06-29 设计创作，主要内容包括：一种催化裂化催化剂,含有改性Y型分子筛、氧化铝粘结剂和粘土；所述的改性Y型分子筛的CaO含量为0.3～4重量％,RE<Sub>2</Sub>O<Sub>3</Sub>含量为2～7重量％,氧化钠含量为0.1重量％～0.5重量％,总孔体积为0.33mL/g～0.39mL/g,该改性Y型分子筛的孔径为2nm～100nm的二级孔的孔体积占总孔体积的百分比为10％～25％,晶胞常数为2.440nm～2.455nm,该改性Y型分子筛中非骨架铝含量占总铝含量的百分比不高于20％,晶格崩塌温度不低于1050℃,B酸量与L酸量的比值不低于2.30。该催化裂化催化剂具有更高的重油转化活性和较低的焦炭选择性,具有更高的汽油收率、异构C4收率,汽油中具有更高的异构烃含量。(A catalytic cracking catalyst contains modified Y-type molecular sieve, alumina binder and clay; the CaO content of the modified Y-type molecular sieve is 0.3-4 wt%, and RE content is 2 O 3 The content of the sodium oxide is 2-7 wt%, the content of the sodium oxide is 0.1-0.5 wt%, the total pore volume is 0.33-0.39 mL/g, the percentage of the pore volume of secondary pores with the pore diameter of 2-100 nm in the modified Y-type molecular sieve in the total pore volume is 10-25%, the unit cell constant is 2.440-2.455 nm, the percentage of non-framework aluminum content in the modified Y-type molecular sieve in the total aluminum content is not higher than 20%, the lattice collapse temperature is not lower than 1050 ℃, the acid B amount and the acid B amount are respectively equal toThe ratio of the L acid amount is not less than 2.30. The catalytic cracking catalyst has higher heavy oil conversion activity, lower coke selectivity, higher gasoline yield and isomeric C4 yield, and higher isomeric hydrocarbon content in gasoline.)

1. A catalytic cracking catalyst comprises 10-50 wt% of modified Y-type molecular sieve calculated by dry basis, 10-40 wt% of alumina binder calculated by alumina and 10-80 wt% of clay calculated by dry basis; the modified Y-type molecular sieve has the calcium oxide content of 0.3-4 wt%, the rare earth oxide content of 2-7 wt%, the sodium oxide content of no more than 0.5 wt%, the total pore volume of 0.33-0.39 mL/g, the pore volume of secondary pores with the pore diameter of 2-100 nm accounting for 10-25% of the total pore volume, the unit cell constant of 2.440-2.455 nm, the non-framework aluminum content of the modified Y-type molecular sieve accounting for no more than 20% of the total aluminum content, the lattice collapse temperature of no less than 1050 ℃, and the ratio of the B acid amount to the L acid amount in the total acid amount of the modified Y-type molecular sieve determined by a pyridine adsorption infrared method at 200 ℃ of no less than 2.30.

2. The catalytic cracking catalyst of claim 1, wherein the modified Y-type molecular sieve has secondary pores with a pore diameter of 2-100 nm, the pore volume of which accounts for 15-21% of the total pore volume, the non-framework aluminum content of which accounts for 13-19% of the total aluminum content, and the framework silicon-aluminum ratio which is SiO₂/Al₂O₃The molar ratio is 7.3-14, the lattice collapse temperature of the molecular sieve is 1050-1080 ℃, for example 1050-1063 ℃, and the total acid of the modified Y-type molecular sieve is measured at 200 ℃ by a pyridine adsorption infrared methodThe ratio of the amount of the B acid to the amount of the L acid in the amount is 2.4-4.2.

3. The catalytic cracking catalyst according to claim 1, wherein the modified Y-type molecular sieve has a relative crystal retention of 35% or more, for example, 36 to 45%, after severe aging at 800 ℃ under normal pressure in a 100% steam atmosphere for 17 hours.

4. The catalytic cracking catalyst of claim 1, wherein the modified Y-type molecular sieve has a relative crystallinity of 58 to 68%.

5. The catalytic cracking catalyst according to any one of claims 1 to 4, wherein the modified Y-type molecular sieve has a calcium oxide content of 0.3 to 4 wt%, a rare earth oxide content of 2 to 7 wt%, a sodium oxide content of 0.2 to 0.5 wt%, a unit cell constant of 2.442 to 2.452nm, and a framework Si/Al ratio of 8 to 12.6.

6. A preparation method of a catalytic cracking catalyst comprises the steps of 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, wherein the preparation method of the modified Y-type molecular sieve comprises the following steps:

(1) contacting the NaY molecular sieve with soluble calcium salt and rare earth salt to carry out ion exchange reaction, filtering, washing and optionally drying to obtain the Y-type molecular sieve with conventional unit cell size, wherein the content of sodium oxide is reduced, and the Y-type molecular sieve contains calcium and rare earth;

(2) roasting the calcium-and rare earth-containing Y-type molecular sieve with the conventional unit cell size and reduced sodium oxide content for 4.5-7 hours at the temperature of 350-480 ℃ in the atmosphere of 30-90 vol% of water vapor, and optionally drying to obtain the Y-type molecular sieve with the reduced unit cell constant;

(3) according to SiCl₄: the Y-type molecular sieve with reduced unit cell constant is 0.1-0.7: 1 weight ratio of the Y-type molecular sieve with reduced unit cell constant to silicon tetrachloride gas, the reaction temperature is 200-650 ℃, and the reaction is carried outThe reaction time is 10 minutes to 5 hours, and the modified Y-type molecular sieve is obtained by washing and filtering.

7. The process of claim 6, wherein said calcium and rare earth containing Y-type molecular sieve having a conventional unit cell size with reduced sodium oxide content in step (1) has a unit cell constant of 2.465 to 2.472nm and a sodium oxide content of not more than 8.8 wt%; the unit cell constant of the Y-type molecular sieve with the reduced unit cell constant obtained in the step (2) is 2.450 nm-2.462 nm, and the water content in the Y-type molecular sieve with the reduced unit cell constant is not more than 1 weight percent.

8. The method according to claim 7, wherein in the step (1), the calcium content of the calcium and rare earth-containing Y-type molecular sieve with the reduced sodium oxide content and the conventional unit cell size is 0.4 to 3.9 wt% in terms of CaO, and the rare earth content is Re in terms of Re₂O₃2 to 7 wt%, a sodium oxide content of 4 to 8.8 wt%, for example, 5.5 to 8.5 wt%, and a cell constant of 2.465nm to 2.472 nm.

9. The method of claim 6, wherein the step (1) of contacting the NaY molecular sieve with the soluble calcium salt and the rare earth salt solution to perform the ion exchange reaction comprises the following steps of: soluble calcium salt: soluble rare earth salt: h₂O is 1: 0.009-0.28: 0.005-0.09: 5-15, mixing the NaY molecular sieve, the soluble calcium salt, the soluble rare earth salt and water, and stirring.

10. The method of claim 6 or 9, wherein the step (1) of contacting the NaY molecular sieve with a soluble calcium salt and a rare earth salt solution to perform an ion exchange reaction comprises: mixing NaY molecular sieve with water, adding soluble calcium salt and/or soluble calcium salt solution and soluble rare earth salt and/or soluble rare earth salt solution under stirring to perform ion exchange reaction, filtering and washing; the conditions of the ion exchange reaction are as follows: the exchange temperature is 15-95 ℃, and the exchange time is 30-120 minutes; the soluble calcium salt solution and the rare earth salt solution are aqueous solutions of soluble calcium salt and soluble rare earth salt; the soluble calcium salt is calcium chloride and/or calcium nitrate, and the soluble rare earth salt is rare earth chloride and/or rare earth nitrate.

11. The method of claim 6, wherein the roasting temperature in the step (2) is 380-460 ℃, the roasting atmosphere is 40-80% of water vapor atmosphere, and the roasting time is 5-6 hours.

12. The method of claim 6, wherein the washing method in step (3) is washing with water under the washing conditions that the molecular sieve: h₂O is 1: 6-15, the pH value is 2.5-5.0, and the washing temperature is 30-60 ℃.

13. A catalytic cracking method comprises the step of carrying out contact reaction on heavy oil and a catalytic cracking catalyst under FCC conditions, wherein the catalytic cracking catalyst is the catalytic cracking catalyst according to any one of claims 1 to 5; the FCC conditions are, for example: the reaction temperature is 480-530 ℃, the reaction time is 1-10 seconds, and the ratio of the solvent to the oil is 3-20: 1 weight ratio.

Technical Field

The invention relates to a heavy oil catalytic cracking catalyst and a preparation method thereof.

Background

At present, the hydrothermal method is mainly adopted for industrially preparing the high-silicon Y-type zeolite. The rare earth-containing high-silicon Y-type zeolite can be prepared by carrying out multiple rare earth ion exchange and multiple high-temperature roasting on NaY zeolite, which is the most conventional method for preparing the high-silicon Y-type zeolite, but the rare earth high-silicon Y-type zeolite prepared by a hydrothermal method has the following defects: because the structure of the zeolite can be damaged by too harsh hydrothermal treatment conditions, the Y-type zeolite with high silica-alumina ratio can not be obtained; while the production of extra-framework aluminum is beneficial for improving the stability of the zeolite and forming new acid centers, the excess extra-framework aluminum reduces the selectivity of the zeolite; in addition, many dealumination cavities in the zeolite cannot be timely supplemented by silicon migrated from the framework, so that lattice defects of the zeolite are often caused, and the crystallization retention of the zeolite is low. And because the conventional Y molecular sieve only contains rare earth, silicon, aluminum and other elements, the adjustment of the structure and the performance of the conventional Y molecular sieve is limited in a certain range, and the composition of a product is often stabilized in a certain range. Therefore, the thermal and hydrothermal stability of the rare earth-containing high-silicon Y-type zeolite prepared by the hydrothermal method is poor, which is shown in that the lattice collapse temperature is low, the crystallinity retention rate and the specific surface area retention rate are low after hydrothermal aging, and the selectivity is poor. Moreover, the content of isomeric hydrocarbon in the isomeric C4 and gasoline produced by the catalyst prepared in the conventional Y molecular sieve is stable in a certain range and is difficult to increase.

In U.S. Pat. Nos. 4,849,287 and 4,4429053, NaY zeolite is exchanged with rare earth ions and then treated with water vapor, in the method, the aluminum removal of zeolite is difficult in the water vapor treatment process due to the shielding effect and support of the rare earth ions, the unit cell parameters of zeolite before the water vapor treatment are increased to 2.465-2.475 nm, the unit cell parameters after the treatment are 2.420-2.464 nm, and the temperature required for reducing the unit cell parameters is high (593-733 ℃).

In the processes provided in US5340957 and US5206194, Si of NaY zeolite is used as the starting materialO₂/Al₂O₃The ratio is 6.0, and the method is to perform rare earth exchange of NaY and then perform hydrothermal treatment, and has the disadvantages of the aforementioned U.S. Pat. Nos. 4,849,287 and 4429053.

Gas phase chemical processes are another important process for preparing high silica zeolites first reported by Beyer and Mankui in 1980. The gas phase chemical method generally adopts SiCl under the protection of nitrogen₄Reacting with anhydrous NaY zeolite at a certain temperature. Fully utilizes SiCl in the whole reaction process₄The supplied foreign Si source completes dealuminization and silicon supplement reaction at one time through isomorphous substitution. U.S. Pat. Nos. 4,42737,178, U.S. Pat. No. 4,4438178, Chinese patent Nos. CN1382525A, CN1194941A and CN1683244A disclose the use of SiCl₄A process for preparing ultra-stable Y-type zeolite by gas-phase chemical dealumination. However, gas phase ultrastable molecular sieves have few secondary pores.

Zhuhuayuan (Petroleum institute, 2001, 17(6):6-10) et al proposed the effect of magnesium-containing modified molecular sieve on the performance of FCC catalyst. Researches find that the FCC catalyst containing the Mg and Ca molecular sieves has strong heavy oil conversion capability, high hydrogen transfer reaction activity and higher isobutane product content. However, the Y molecular sieve prepared by the method has poor thermal and hydrothermal stability, and can only increase the content of isobutane but not effectively increase the content of isomeric hydrocarbon in gasoline under certain conditions.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a catalytic cracking catalyst which has higher thermal and hydrothermal stability, higher gasoline yield and good selectivity of more-produced isomeric C4 and isomeric hydrocarbon and coke in gasoline, and the catalyst contains a Y-type molecular sieve. The invention also aims to provide a preparation method and an application method of the catalyst.

The invention provides a catalytic cracking catalyst, which comprises 10-50 wt% of modified Y-type molecular sieve and 10-40 wt% of alumina on a dry basisA binder and 10 to 80 wt% clay on a dry basis; the modified molecular sieve has the calcium oxide content of 0.3-4 wt%, the rare earth oxide content of 2-7 wt%, the sodium oxide content of not more than 0.5 wt%, such as 0.1-0.5 wt%, the total pore volume of 0.33-0.39 mL/g, the percentage of the pore volume of secondary pores with the pore diameter of 2-100 nm in the total pore volume of the modified Y-type molecular sieve is 10-25%, the unit cell constant is 2.440-2.455 nm, and the framework silicon-aluminum ratio (SiO/Al)₂/Al₂O₃Molar ratio) is: 7.3-14.0, the percentage of non-framework aluminum content in the molecular sieve to the total aluminum content is not higher than 20%, the lattice collapse temperature is not lower than 1050 ℃, and the ratio of the B acid amount to the L acid amount in the total acid amount of the modified Y-type molecular sieve measured by a pyridine adsorption infrared method at 200 ℃ is not lower than 2.30.

In the catalytic cracking catalyst provided by the invention, the lattice collapse temperature (also called structure collapse temperature) of the modified Y-type molecular sieve is not lower than 1050 ℃, preferably 1050-1080 ℃, for example 1052-1065 ℃ or 1050-1063 ℃.

In the catalytic cracking catalyst provided by the invention, the ratio of the B acid amount to the L acid amount in the total acid amount of the modified Y-type molecular sieve determined by a pyridine adsorption infrared method at 200 ℃ is preferably 2.4-4.2, 2.4-3.5 or 2.3-5.0.

In the catalytic cracking catalyst provided by the invention, the unit cell constant of the modified Y-type molecular sieve is 2.440-2.455 nm, such as 2.442-2.452 nm.

In the catalytic cracking catalyst provided by the invention, the modified Y-type molecular sieve is a high-silicon Y-type molecular sieve, and the framework silicon-aluminum ratio (SiO) of the modified Y-type molecular sieve₂/Al₂O₃Molar ratio) of 7.3 to 14.0, for example: 8.5 to 12.6.

In the catalytic cracking catalyst provided by the invention, the non-framework aluminum content of the modified Y-type molecular sieve accounts for not more than 20% of the total aluminum content, for example, 10-20% or 13-19% by weight.

In the catalytic cracking catalyst provided by the invention, the modified Y-type molecular sieve has a crystal retention of over 35%, such as 36-45%, 38-44%, 35-48% or 39-45%, after aging for 17 hours at 800 ℃ under normal pressure and in a 100 volume% steam atmosphere. The normal pressure is 1 atm.

In the catalytic cracking catalyst provided by the invention, the relative crystallinity of the modified Y-shaped molecular sieve is not less than 58%, such as 58-68%, 59-63%, 60-70% or 60-66%.

In the catalytic cracking catalyst provided by the invention, according to an implementation mode, the specific surface area of the modified Y-shaped molecular sieve is 620-670 m²The/g is, for example, 630 to 660m²/g。

In the catalytic cracking catalyst provided by the invention, preferably, the total pore volume of the modified Y-type molecular sieve is 0.35-0.39 mL/g, for example, 0.35-0.375 mL/g.

In the catalytic cracking catalyst provided by the invention, the pore volume of the modified Y-type molecular sieve with the secondary pores with the pore diameter (diameter) of 2.0-100 nm accounts for 10-25% of the total pore volume, and preferably 15-21%, or 15-23%, or 17-21%.

In one embodiment, the modified Y-type molecular sieve has a micropore volume of 0.25-0.35 mL/g, such as 0.26-0.32 mL/g or 0.28-0.31 mL/g.

In the catalytic cracking catalyst provided by the invention, the modified Y-type molecular sieve contains calcium and rare earth elements, the content of calcium oxide in the modified Y-type molecular sieve is 0.3-4 wt%, such as 0.5-3.5 wt% or 0.9-3 wt% or 0.9-4 wt% calculated by CaO, and Re is used in the modified Y-type molecular sieve₂O₃The rare earth content is preferably 2 to 7 wt%, for example 2.5 to 6.5 wt%, for example 2.5 to 4.5 wt%.

The modified Y-type molecular sieve provided by the invention has the sodium oxide content of not more than 0.5%, and can be 0.15-0.5 wt%, for example, 0.3-0.5 wt%, or 0.20-0.45 wt%, or 0.25-0.4 wt%.

The catalyst provided by the invention can also contain other molecular sieves except the modified Y-type molecular sieve, and the content of the other molecular sieves is, for example, 0-40 wt%, for example, 0-30 wt% or 1-20 wt% in terms of dry basis based on the weight of the catalyst. The other molecular sieve is selected from one or more of molecular sieves used in catalytic cracking catalysts, such as zeolite with MFI structure, zeolite Beta, other Y-type zeolite, and non-zeolite molecular sieves. Preferably, the content of the other Y-type molecular sieve is not more than 40 wt% on a dry basis, for example, 1 to 40 wt% or 0 to 20 wt%. Such as one or more of REY, REHY, DASY, SOY, PSRY, MFI structure zeolites such as one or more of HZSM-5, ZRP, ZSP, beta zeolites such as H β, non-zeolitic molecular sieves such as one or more of aluminum phosphate molecular sieves (AlPO molecular sieves), silicoaluminophosphate molecular sieves (SAPO molecular sieves).

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

In the catalytic cracking catalyst provided by the invention, the clay is selected from one or more of clays used as a cracking catalyst component, 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. Preferably, the content of the clay in the catalytic cracking catalyst provided by the invention is 20-55 wt% or 30-50 wt% on a dry basis.

In the catalytic cracking catalyst provided by the invention, the content of the alumina binder is 10-40 wt%, for example 20-35 wt%. The alumina binder of the present invention is one or more selected from various forms of alumina, hydrated alumina and alumina sol generally used in cracking catalysts. For example, one or more selected from gamma-alumina, eta-alumina, theta-alumina, chi-alumina, pseudo-Boehmite (Pseudobioemite), diaspore (Boehmite), Gibbsite (Gibbsite), Bayer stone (Bayerite) and alumina sol, preferably pseudo-Boehmite and alumina sol, for example, the catalytic cracking catalyst contains 2-15 wt% of alumina sol, preferably 3-10 wt% of alumina sol, and 10-30 wt% of alumina sol, preferably 15-25 wt% of pseudo-Boehmite.

The catalyst of the present invention 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 and drying are the prior art, and the invention has no special requirements.

The preparation method of the catalytic cracking catalyst comprises the steps of preparing a modified Y-shaped molecular sieve, forming slurry comprising the modified Y-shaped molecular sieve, an alumina binder, clay and water, and spray drying, wherein the preparation method of the modified Y-shaped molecular sieve comprises the following steps:

(1) contacting NaY molecular sieve with soluble calcium salt and rare earth salt solution to carry out ion exchange reaction

Filtering and washing to obtain the Y-type molecular sieve with conventional unit cell size and reduced sodium oxide content and containing calcium and rare earth;

wherein the soluble calcium salt solution is also called calcium salt solution, and the soluble rare earth salt solution is also called rare earth salt solution;

(2) sieving the calcium and rare earth-containing Y-type molecular sieve with conventional unit cell size and reduced sodium oxide content

Carrying out modification treatment, optionally drying to obtain the Y-type molecular sieve with reduced unit cell constant, wherein the modification treatment is

Subjecting said calcium and rare earth containing conventional unit cell size Y-type molecular sieve having a reduced sodium oxide content to temperature

An atmosphere containing 30 to 90 vol% of steam at 350 to 480 ℃ (also referred to as an atmosphere containing 30 to 90 vol% of steam or

Weighing 30-90% of water vapor) and roasting for 4.5-7 hours;

(3) mixing the Y-type molecular sieve sample with SiCl, wherein the unit cell constant is reduced₄Gas is contacted and reacted at the temperature of 200-650 ℃, wherein SiCl is contained₄: weight of Y-type molecular sieve having reduced unit cell constant obtained in step (2) on a dry basisThe ratio is 0.1-0.7: 1, reacting for 10 minutes to 5 hours, and then washing and filtering to obtain the modified Y-type molecular sieve. Wherein the water content of the Y-type molecular sieve having a reduced unit cell constant is preferably not more than 1% by weight; if the water content in the Y-type molecular sieve obtained by modification treatment in the step (2) (in a Y-type molecular sieve sample obtained by roasting) is not more than 1 wt%, the Y-type molecular sieve can be directly used for contacting silicon tetrachloride to carry out the reaction, and if the water content in the Y-type molecular sieve obtained by roasting in the step (2) is more than 1 wt%, the Y-type molecular sieve with the reduced unit cell constant obtained by roasting in the step (2) is dried to ensure that the water content is less than 1 wt%.

The invention also provides a catalytic cracking method, which comprises the step of carrying out contact reaction on heavy oil and the catalytic cracking catalyst provided by the invention under the condition of heavy oil FCC. The heavy oil such as one or more of vacuum wax oil, atmospheric residue oil, vacuum residue oil and heavy deasphalted oil, the FCC condition is a reaction condition of fluidized catalytic cracking of the heavy oil, and generally, the reaction temperature of the reaction is 480-530 ℃, the reaction time is 1-10 seconds, and the agent-oil ratio is 3-20: 1 weight ratio.

The catalytic cracking catalyst provided by the invention contains the modified Y-type molecular sieve with high thermal and hydrothermal stability, has higher hydrothermal stability, is used for heavy oil catalytic cracking, has higher heavy oil conversion activity and lower coke selectivity compared with the existing catalytic cracking catalyst containing the Y-type molecular sieve, has higher gasoline yield, light oil yield, total liquid yield and isomeric C4 yield, and has more isomeric hydrocarbons in gasoline. For example, the catalytic cracking catalyst SC3 having a modified Y molecular sieve SZ3 content of 30.0 wt%, a kaolin content of 42 wt%, a pseudoboehmite content of 25 wt%, and an alumina sol content of 3 wt% prepared by the method of the present invention was evaluated with heavy oil on a fixed fluidized bed ACE evaluation apparatus, and the SC3 catalyst had a heavy oil conversion rate of 74.61 wt%, a liquefied gas yield of 16.83 wt%, a gasoline yield of 52.05 wt%, an isomeric C4 hydrocarbon yield of 7.21 wt%, a hydrocarbon content in gasoline of 38.94 wt%, a light oil yield of 69.26 wt%, a total liquid yield of 86.09 wt%, and a coke selectivity of 5.91%, whereas the catalyst DC3 having the same content of the high-silica molecular sieve component prepared by the conventional method had a heavy oil conversion rate of 74.47 wt%, a liquefied gas yield of 15.79 wt%, a gasoline yield of 50.86 wt%, an isomeric C4 hydrocarbon yield of 5.58 wt%, the content of isomeric hydrocarbon in the gasoline is 36.82 percent by weight, the yield of light oil is 68.09 percent by weight, the total liquid yield is 83.88 percent by weight, and the selectivity of coke is 8.61 percent; therefore, the catalyst has higher heavy oil conversion capacity, higher yield of isomeric C4 and gasoline, higher content of isomeric hydrocarbon in the gasoline and better coke selectivity. The light oil micro-reverse evaluation result shows that the catalytic cracking catalyst prepared by the invention has higher activity and hydrothermal stability.

The catalytic cracking method provided by the invention has the advantages of higher heavy oil conversion capacity, higher liquefied gas yield and isomeric C4 yield, higher gasoline yield, higher content of isomeric hydrocarbon in gasoline, higher light oil yield and total liquid yield, and better coke selectivity. Can be used for increasing the yield of gasoline with higher content of isomeric hydrocarbon and simultaneously increasing the yield of C4 isomeric hydrocarbon.

In the present invention, the isoparaffin refers to a chain isoparaffin and a chain isoolefin. The increase of the content of the isomeric hydrocarbon is beneficial to improving the quality of the gasoline, for example, the octane number of the gasoline can be kept from being reduced under the condition of reducing the content of aromatic hydrocarbon and olefin.

Detailed Description

The catalytic cracking catalyst provided by the invention contains 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 weight of the catalyst is taken as a reference. Preferably, the catalytic cracking catalyst contains 25 to 40 wt% of the modified Y-type molecular sieve on a dry basis, 20 to 35 wt% of an alumina binder on an alumina basis, and 30 to 50 wt% of clay on a dry basis.

The catalytic cracking catalyst provided by the invention contains a modified Y-shaped molecular sieve, and in one embodiment, the calcium oxide content of the modified Y-shaped molecular sieve is 0.3-4 wt%, preferably 0.5-3.5 wt%% of rare earth oxide is 2 to 7% by weight, preferably 2.5 to 6.5% by weight, for example 2.5 to 4.5% by weight. The content of sodium oxide is 0.1 to 0.5 wt%, for example, 0.3 to 0.5 wt% or 0.13 to 0.4 wt%, the total pore volume is 0.33 to 0.39mL/g, the percentage of the pore volume of the secondary pores having a pore diameter of 2 to 100nm to the total pore volume is 10 to 25%, preferably 15 to 21%, the unit cell constant is 2.440 to 2.455nm, and the framework silicon-aluminum ratio (SiO 2.440 to 2.455 nm)₂/Al₂O₃Molar ratio) is: 7.3-14.0, the percentage of non-framework aluminum content in the molecular sieve in the total aluminum content is not higher than 20%, preferably 13-19, the relative crystallinity is not lower than 58%, the lattice collapse temperature is 1050-1080 ℃ or 1052-1065 ℃, and the ratio of the B acid amount to the L acid amount in the total acid amount of the modified Y-type molecular sieve measured at 200 ℃ by using a pyridine adsorption infrared method is not lower than 2.30, preferably 2.4-4.2.

In the catalytic cracking catalyst provided by the invention, the preparation process of the modified Y-type molecular sieve comprises the step of contacting the Y-type molecular sieve with silicon tetrachloride to carry out dealuminization and silicon supplementation reaction.

In the preparation method of the modified Y-type molecular sieve, in the step (1), the NaY molecular sieve is contacted with a soluble calcium salt and a rare earth salt solution to carry out an ion exchange reaction, so that the Y-type molecular sieve with the conventional unit cell size and the reduced sodium oxide content and containing calcium is obtained. The soluble calcium salt and the rare earth salt are a calcium salt capable of being dissolved in a solvent and a rare earth salt capable of being dissolved in a solvent, and the contacting can be carried out by contacting the NaY molecular sieve with a soluble calcium salt solution and a soluble rare earth salt for ion exchange (for example, contacting with a rare earth salt solution and then a calcium salt solution, or contacting with a calcium salt solution and then a rare earth salt solution), or contacting with a solution containing a soluble calcium salt and a soluble rare earth salt (also referred to as a mixed solution of a soluble calcium salt and a rare earth salt in the invention), and the mixed solution of the soluble calcium salt and the soluble rare earth salt can be obtained by mixing the soluble calcium salt and the soluble rare earth salt with a solvent such as 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 is2.465-2.472 nm, framework silicon-aluminum ratio (SiO)₂/Al₂O₃Molar ratio) of 4.5 to 5.2, a relative crystallinity of 85% or more, for example, 85 to 95%, and a sodium oxide content of 13.0 to 13.8% by weight. The NaY molecular sieve, the soluble calcium salt and the rare earth salt solution are subjected to ion exchange reaction, the exchange temperature is preferably 15-95 ℃, for example 65-95 ℃, and the exchange time is preferably 30-120 minutes, for example 45-90 minutes. NaY molecular sieve (calculated on a dry basis), calcium salt (calculated as CaO), rare earth salt (calculated as RE)₂O₃Meter): h₂O is 1: 0.009-0.28: 0.005-0.09: 5-15 by weight. The rare earth salt is soluble rare earth salt, and the calcium salt is soluble calcium salt. In one embodiment, the ion exchange reaction of the NaY molecular sieve in contact with the soluble calcium salt and the rare earth salt solution comprises the following steps of₂The method comprises the steps of mixing NaY molecular sieve (also called NaY zeolite), calcium salt, rare earth salt and water in a weight ratio of 1: 0.009-0.27: 0.005-0.09: 5-15, and carrying out exchange of calcium ions and rare earth ions with sodium ions by stirring at 15-95 ℃, such as 65-95 ℃, preferably for 30-120 minutes. The NaY molecular sieve, the calcium salt, the rare earth salt and water are mixed to form a mixture, the NaY molecular sieve and the water can be formed into slurry, and then the calcium salt and/or the calcium salt water solution, the rare earth salt and/or the rare earth salt water solution are added into the slurry. The calcium salt is preferably calcium chloride and/or calcium nitrate. The rare earth salt is preferably rare earth chloride and/or rare earth nitrate. The rare earth such as one or more of La, Ce, Pr, Nd and misch metal, preferably, the misch metal contains one or more of La, Ce, Pr and Nd, or further contains at least one of rare earth other than La, Ce, Pr and Nd. The washing in step (1) is intended to wash out exchanged sodium ions, and for example, deionized water or decationized water may be used for washing. Preferably, the calcium content of the calcium and rare earth containing Y-type molecular sieve with conventional unit cell size and reduced sodium oxide content obtained in step (1) is 0.3-10 wt% calculated on CaO, such as 0.4-9 wt%, or 0.4-6 wt%, or 1-5 wt%, or 2-4 wt%, or 0.3-4 wt%, or 3-6 wt%, or 3.5-5.5 wt%Or 4-9 wt%, the rare earth content being Re₂O₃2 to 8 wt% or 2.1 to 7 wt% or 3 to 7 wt% or 4 to 6 wt%, sodium oxide content of not more than 9 wt%, for example, 5.5 to 8.5 wt% or 5.5 to 7.5 wt%, and unit cell constant of 2.465nm to 2.472 nm.

In the preparation method of the modified Y-type molecular sieve, the Y-type molecular sieve containing calcium and rare earth in the conventional unit cell size is roasted for 4.5-7 hours at the temperature of 350-480 ℃ under the atmosphere of 30-90 vol% of water vapor in step (2), preferably, the roasting temperature in step (2) is 380-460 ℃, the roasting atmosphere is 40-80 vol% of water vapor, and the roasting time is 5-6 hours. The water vapor atmosphere contains 30-90% by volume, preferably 40-80% by volume of water vapor, and also contains other gases, such as one or more of air, helium or nitrogen. The Y-type molecular sieve with the reduced unit cell constant in the step (2) has the unit cell constant of 2.450 nm-2.462 nm. Preferably, the calcined molecular sieve is also dried in step (2) so that the water content in the Y-type molecular sieve having a reduced unit cell constant is preferably not more than 1 wt%.

In the preparation method of the catalytic cracking catalyst, the SiCl is added in the step (3)₄: the weight ratio of the Y-type zeolite (on a dry basis) is preferably 0.3-0.6: 1, the reaction temperature is preferably 350-500 ℃, and the washing method in the step (3) can adopt a conventional washing method, and can be washed by water, such as decationized water or deionized water, so as to remove Na remained in the zeolite⁺，Cl^-And Al³⁺Etc. soluble by-products, for example the washing conditions may be: the weight ratio of the washing water to the molecular sieve can be 5-20: 1, typically molecular sieve: h₂The weight ratio of O is 1: 6-15, the pH value is preferably 2.5-5.0, and the washing temperature is 30-60 ℃. Preferably, the washing is performed such that no free Na is detected in the washing solution after washing⁺，Cl^-And Al³⁺Plasma, Na in the washing liquid after washing in general⁺、Cl^-And Al³⁺The content of each ion is not more than 0.05 wt%。

In the preparation method of the catalytic cracking catalyst provided by the invention, one embodiment of the preparation method of the modified Y-type molecular sieve comprises the following steps:

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

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

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

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