RU2802819C2 - Modified y-type molecular sieves, catalytic cracking catalyst containing them, catalyst production and application of sieves - Google Patents

Abstract

FIELD: molecular sieves.

SUBSTANCE: modified Y-type molecular sieve for catalytic cracking of hydrocarbon oils is described, having a calcium content of 0.3-4 wt% in terms of calcium oxide, a rare earth element content of 2-7 wt% in terms of rare earth oxide, and a sodium content of not more than 0.5 wt% in terms of sodium oxide, in terms of dry matter and based on the weight of the specified modified Y-type molecular sieve; moreover, the modified Y-type molecular sieve has a total pore volume of 0.33-0.39 ml/g, the ratio of the volume of secondary pores with a pore size of 2-100 nm to the total pore volume of 10-25%, a crystal lattice constant of 2.440-2.455 nm, the ratio the content of non-lattice aluminium to the total aluminium content is not more than 20%, the temperature of destruction of the crystal lattice is not lower than 1050°C and the ratio of Bronsted acid to Lewis acid in the total acid content is not less than 2.30, as determined by infrared spectroscopy of adsorbed pyridine at 200°C. A method for producing the above-described modified molecular sieve, a catalytic cracking catalyst containing the above-described modified molecular sieve, and the use of the described catalyst in catalytic cracking are described.

EFFECT: use of the proposed molecular sieve in catalytic cracking increases the activity of heavy oil conversion, provides low coke selectivity, increases the yield of gasoline and branched C4 hydrocarbons.

15 cl, 5 tbl, 22 ex

Description

Link to related applications

This application claims priority to Chinese Patent Application No. 201810714296.1 entitled “Modified Υ-type molecular sieve with high stability for increasing the yield of branched C4 hydrocarbons and its production,” filed on June 29, 2018; and priority according to Chinese Patent Application No. 201810715238.0 entitled “Fatalytic Cracking Catalyst” filed on June 29, 2018, which are incorporated herein by reference in their entirety.

Field of technology to which the present invention relates

The present application relates to the technical field of molecular sieves and catalytic cracking, in particular to a modified molecular sieve type Υ, a catalytic cracking catalyst containing it, its preparation and use thereof.

BACKGROUND OF THE INVENTION

Currently, high silica-content type Υ molecular sieves (also called type Y zeolites) are produced commercially mainly by the hydrothermal process. The hydrothermal method is the most commonly used method for producing high silica Y type molecular sieve, in which the NaY type molecular sieve is subjected to repeated ion exchange with a rare earth element and calcined at high temperature to obtain a rare earth containing high silica Y type molecular sieve silicon However, rare earth-containing Y-type molecular sieves with high silica content produced by the hydrothermal process have the following disadvantages: since the structure of the molecular sieve may be damaged under severe hydrothermal processing conditions, producing Y-type molecular sieves with a high silica-alumina ratio may be difficult; Although creating non-lattice aluminum is beneficial for improving the stability of the molecular sieve and the formation of new acid sites, excessive amounts of non-lattice aluminum can reduce the selectivity of the molecular sieve; In addition, many dealuminated voids in the molecular sieve may not be timely supplemented with silicon migrating from the crystal lattice so that lattice defects can be created in the molecular sieve, and the retention of crystallinity of the molecular sieve is low. In addition, since conventional Y-type molecular sieves contain only rare earth elements, silicon, aluminum and some other elements, the control of their structure and performance characteristics is limited to some extent, so that the composition of the product is generally stabilized within a certain range. Consequently, rare earth-containing high silica Y-type molecular sieves prepared by the hydrothermal process exhibit poor thermal and hydrothermal stability, as reflected by their low lattice breakdown temperature, poor retention of crystallinity and specific surface area after hydrothermal aging, and poor selectivity.

In the method disclosed in US 4,584,287 and US 4,429,053, the NaY type molecular sieve is first ion exchanged with a rare earth element and then treated with steam, which makes dealumination of the molecular sieve by steam treatment difficult due to the shielding and supporting effect of the rare earth ion. The lattice parameter of the molecular sieve increases to 2.465-2.475 nm before steam treatment and is 2.420-2.464 nm after treatment, and the temperature required to reduce the lattice parameter is relatively high (593-733°C).

In the method disclosed in US Pat. No. 5,340,957 and US Pat. No. 5,206,194, a NaY type molecular sieve with a SiO ₂ /Al ₂ O ₃ ratio of 6.0 is used as a starting material, and NaY is also subjected to ion exchange with a rare earth element and then hydrothermal treatment. Thus, the method also has the disadvantage of the above-mentioned US patents No. 4584287 and No. 4429053.

Another method for producing high silica Y type molecular sieves is the gas phase chemical process, which is another important method for producing high silica molecular sieves first reported by Beyer and Mankui in 1980. The gas phase chemical process generally involves reaction of SiCl ₄ and anhydrous molecular sieve such as NaY in a nitrogen atmosphere at a certain temperature. The entire reaction process fully utilizes the external source of Si provided by SiCl ₄ , and the dealumination and silicon addition reaction can be completed simultaneously through isomorphic substitution. US Patents No. 4273753 and No. 4438178 and Chinese Patent Application Publications Nos. CN 1382525 A, CN 1194941 A, CN 1683244 A disclose a method for producing ultra-stable type Υ molecular sieves by gas-phase chemical dealumination with SiCl ₄ . However, molecular sieves overstabilized in the gas phase process are essentially free of secondary pores.

In addition, the production of branched C4 hydrocarbons and the content of branched hydrocarbons in gasoline produced using catalysts obtained from conventional Y-type molecular sieves stops in a certain range and is difficult to increase. Huayuan Zhu et al. (Acta Petrolei Sinica (Petroleum Processing Section), 2001, 17 (6): 6-10) studied the effect of magnesium-containing modified molecular sieves on the performance of FCC catalysts and reported that FCC catalysts based on Mg, Ca-containing molecular sieves show high performance for heavy oil processing, high activity for the hydrogen transfer reaction and high isobutane productivity. However, the Y-type molecular sieve produced by the method disclosed herein has poor thermal and hydrothermal stability and can only be used to increase isobutane production under certain conditions, but cannot be effectively used to increase the branched hydrocarbon content of gasoline.

The performance of ultrastable molecular sieves produced by the hydrothermal process or the gas phase process known in the art cannot meet the needs for heavy oil and low grade oil processing and gasoline upgrading.

The foregoing description is provided only as background to this application and is not in any way taken as prior art published prior to the filing date of this application.

Brief Disclosure of the Present Invention

The object of the present application is to provide a highly stable modified Y-type molecular sieve, its preparation and its use, which is useful in the catalytic cracking of heavy oil and can enhance the production of branched C4 hydrocarbons and increase the branched hydrocarbon content of gasoline. Another object of the present application is to provide a catalytic cracking catalyst containing a modified Y-type molecular sieve, its preparation and its use, the catalyst showing high thermal and hydrothermal stability, increased yield of gasoline, branched C4 hydrocarbons and branched hydrocarbons in gasoline and good selectivity to coke .

To achieve the above objectives, an aspect of the present application provides a modified Y-type molecular sieve with a calcium content of approximately 0.3-4 wt. % in terms of calcium oxide (CaO), the rare earth element content is approximately 2-7 wt. % in terms of rare earth oxide (RE ₂ O ₃ ) and a sodium content of no more than approximately 0.5 wt. % based on sodium oxide (Na ₂ O) on a dry matter basis and based on the weight of the modified Y-type molecular sieve, wherein the modified Y-type molecular sieve has a total pore volume of approximately 0.33-0.39 ml/g, volume ratio secondary pores with a pore size of 2-100 nm to the total pore volume of approximately 10-25%, lattice constant of approximately 2,440-2,455 nm, ratio of non-lattice aluminum content to total aluminum content of no more than approximately 20%, lattice destruction temperature not lower than approximately 1050°C and a ratio of acid B to acid L in the total acid content of not less than about 2.30, as determined by infrared spectroscopy of adsorbed pyridine at 200°C.

In another aspect, the present application provides a process for producing a modified Y-type molecular sieve, comprising the steps of:

(1) contacting the NaY type molecular sieve with a solution of a soluble calcium salt and a soluble rare earth salt for an ion exchange reaction to produce a Y type molecular sieve containing calcium and a rare earth element having a reduced sodium content;

(2) subjecting the Y-type molecular sieve obtained in step (1) to calcination at a temperature of approximately 350-480°C in an atmosphere of approximately 30-90 vol. % steam for about 4.5-7 hours and optionally drying to obtain a Y-type molecular sieve with a reduced lattice constant; And

(3) contacting the Y-type molecular sieve obtained in step (2) with silicon tetrachloride gas to react at a weight ratio of SiCl ₄ to Y-type molecular sieve with a reduced lattice constant on a dry matter basis ranging from about 0.1: 1 to about 0.7:1 and a reaction temperature of about 200-650° C. for a reaction time of about 10 minutes to about 5 hours to produce a modified Y-type molecular sieve.

In another aspect, the present application provides a modified Y-type molecular sieve produced by a process for producing a modified Y-type molecular sieve as described above.

In yet another aspect, the present application provides a catalytic cracking catalyst containing approximately 10-50 wt. % based on the dry matter of the modified molecular sieve type Υ according to this application, approximately 10-40 wt. % of alumina-based binder in terms of aluminum oxide and approximately 10-80 wt. % based on clay dry matter based on the weight of the catalytic cracking catalyst.

In yet another aspect, the present application provides the use of the modified Y-type molecular sieve of the present application in the catalytic cracking of hydrocarbon oils, comprising the step of contacting the hydrocarbon oil with a catalytic cracking catalyst containing the modified Y-type molecular sieve.

The modified Y-type molecular sieve of the present application has high thermal and hydrothermal stability and can be used as an active component in a catalytic cracking catalyst for converting heavy oil or low-grade oil; used for desulfurization by adsorption of gasoline to increase the octane number of desulfurized gasoline; and used for isodewaxing of lubricating oils. When used in the catalytic cracking of hydrocarbon oils, the modified Y-type molecular sieve shows a high degree of conversion of heavy oil and can provide high yield of liquefied gas, branched C4 hydrocarbons and gasoline, increased content of branched hydrocarbons in the resulting gasoline, high yield of light oil, total liquid yield and good selectivity to coke. A modified Y-type molecular sieve can be used to increase the yield of gasoline with higher branched hydrocarbon content and at the same time increase the yield of C4 branched hydrocarbons.

The catalytic cracking catalyst of the present application containing a modified molecular sieve as an active component has high hydrothermal stability, and when used for heavy oil catalytic cracking, shows higher heavy oil conversion activity and lower coke selectivity, and can provide higher gasoline yield, light oil, total liquid and branched C4 hydrocarbons and higher branched hydrocarbon content in the resulting gasoline compared to existing catalytic cracking catalysts containing Y-type molecular sieves.

Detailed Disclosure of the Present Invention

The present application will now be described in more detail with reference to its embodiments, and it should be noted that the embodiments described in the present invention are presented only for the purpose of illustration and explanation of the present application, while not being limiting in any way.

Any numerical value (including the end values of numerical ranges) provided herein is not limited to the exact value stated, but should be understood to cover any value close to the specified precise value, for example, all possible values within 5% of the specified precise value. Moreover, for any numerical range provided herein, one or more new numerical ranges may be obtained by arbitrarily combining the end values of the range, the end value with a particular value represented in the range, or different particular values represented in the range. Such new numerical ranges should also be considered as specifically disclosed herein.

Unless otherwise specified, terms used herein have the same meaning as commonly understood by those skilled in the art, and if the definition of a term provided herein differs from the common understanding in the art, the definition provided herein , will prevail.

In this application, except where specifically indicated, any material or materials not specified are directly applicable to those known in the art without any modification. In addition, any embodiments described herein may be combined without limitation with one or more other embodiments described herein, and the resulting technical solution or technical idea should be considered part of the original disclosure or the original description of this application, in which case should not be construed as a new issue that has not been disclosed or provided for herein, unless it is obvious to those skilled in the art that such a combination is clearly unreasonable.

The RIPP test methods included in this application can be found in Petrochemical Analysis Methods (RIPP Test Methods), edited by Cuiding YANG et al., Science Press, September 1990, First Edition, ISBN: 7-03-001894-X , pages 263-268, 412-415 and 424-426, which are incorporated herein by reference in their entirety.

All patent and non-patent documents referenced herein, including, without limitation, textbooks and journal articles, are hereby incorporated by reference in their entirety.

As used herein, the term “branched hydrocarbon(s)” refers to isoparaffins and branched alkenes. Increasing the content of branched hydrocarbons is beneficial for improving the quality of gasoline, for example, by maintaining the octane number of gasoline, while the content of aromatic hydrocarbons and olefins is reduced.

As used herein, the term “branched C4 hydrocarbon(s)” refers to isoparaffins and branched C4 alkenes such as isobutane and isobutene.

As used herein, the expression "Y-type molecular sieve with normal lattice constant" means that the lattice constant of the Y-type molecular sieve is in the range of the lattice constant of conventional NaY-type molecular sieve, which is preferably in the range of about 2.465 nm to about 2.472 nm.

As used herein, the term “atmospheric pressure” means a pressure of approximately 1 atm.

As used herein, the weight of the material on a dry matter basis refers to the weight of the solid product obtained after firing the material at 800° C. for 1 hour.

In this application, the terms “Y-type molecular sieve” and “Y-type zeolite” are used interchangeably, and the terms “NaY-type molecular sieve” and “NaY-type zeolite” are also used interchangeably.

In this application, 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. The calcium salt may be any calcium salt soluble in a solvent such as water, preferably calcium chloride and/or calcium nitrate. The rare earth salt may be any rare earth salt soluble in a solvent such as water, preferably a rare earth chloride and/or a rare earth nitrate. The rare earth element may be, for example, one or more of La, Ce, Pr, Nd and mixed rare earth elements. Preferably, the mixed rare earth elements contain one or more of La, Ce, Pr and Nd, or may also contain at least one rare earth element other than La, Ce, Pr and Nd.

In a first aspect, the present application provides a modified type Υ molecular sieve with a calcium content of approximately 0.3-4 wt. %, for example approximately 0.5-3.5 wt. %, approximately 0.9-3 wt. % or approximately 0.9-4 wt. %, in terms of calcium oxide; rare earth element content of approximately 2-7 wt. %, preferably approximately 2.5-6.5 wt. %, for example approximately 2.5-4.5 wt. %, in terms of rare earth oxide and a sodium content of not more than approximately 0.5 wt. %, which can be approximately 0.1-0.5 wt. %, for example approximately 0.13-0.4 wt. %, preferably approximately 0.15-0.5 wt. %, for example approximately 0.2-0.5 wt. %, approximately 0.3-0.5 wt. %, 0.20-0.45 wt. % or 0.25-0.4 wt. %, in terms of sodium oxide.

In a preferred embodiment, the modified Y type molecular sieve of the present application is substantially free of modifying ions or elements other than calcium and rare earth elements, including, but not limited to, P, Mg, Ga, Cr, Zn, Cu and the like. For example, each modifying ion or element other than calcium and rare earth element may be present in an amount (based on oxides) of less than about 0.1 wt. %, for example, less than about 0.05 wt. % or less than about 0.01 wt. %, based on the dry matter weight of the modified Y-type molecular sieve.

In the modified Y-type molecular sieve of the present application, the ratio of secondary pore volume with a pore size (i.e., pore diameter) of 2-100 nm to the total pore volume is about 10-25%, preferably about 15-23%, for example about 15- 21% or 17-21%.

In the modified Y-type molecular sieve of the present application, the ratio of non-lattice aluminum content to total aluminum content is no more than about 20%, such as about 10% to about 20% or about 13% to about 19%.

The modified type Y molecular sieve of the present application is a high silica content type Y molecular sieve having a lattice silica-alumina ratio (in terms of SiO ₂ /Al ₂ O ₃ molar ratio) of approximately 7.3-14. 0, for example, approximately 8-12.6.

The modified Y-type molecular sieve of the present application has a lattice breakdown temperature (also called structure breakdown temperature) of not lower than about 1050°C. Preferably, the molecular sieve has a lattice breakdown temperature of about 1050-1080°C, for example about 1050-1063°C or about 1052-1065°C.

In the modified Y type molecular sieve of the present application, the ratio of acid B to acid L in the total acid content is not less than about 2.30, preferably about 2.4-3.5, 2.4-4.2 or 2.3-5 ,0, which was determined using infrared spectroscopy of adsorbed pyridine at 200°C.

The modified Υ type molecular sieve of the present application has a lattice constant of about 2.440-2.455 nm, for example about 2.442-2.452 nm.

In a preferred embodiment, the modified Y-type molecular sieve of the present application has a relative crystallinity of at least about 58%, such as about 58-68%, about 59-63%, about 60-70%, or about 60-66%.

The modified Y-type molecular sieve of the present application is characterized by retention of crystallinity of no less than about 35%, such as about 36-45%, about 38-44%, about 35-48%, or about 39-45%, after aging at 800° C. under atmospheric pressure of 100 vol. % steam atmosphere for 17 hours.

In a preferred embodiment, the modified Y type molecular sieve of the present application has a specific surface area of approximately 620-670 m ² /g, for example, approximately 630-660 m ² /g.

The modified Y type molecular sieve of the present application has a total pore volume of about 0.33-0.39 ml/g, preferably about 0.35-0.39 ml/g, for example about 0.35-0.375 ml/g.

In a preferred embodiment, the modified Y-type molecular sieve of the present application has a micropore volume of about 0.25-0.35 ml/g, for example, about 0.26-0.32 ml/g or about 0.28-0.31 ml/ G.

In a preferred embodiment, the modified Y-type molecular sieve of the present application is prepared by a method for producing a modified Y-type molecular sieve as described herein below.

The modified Y type molecular sieve of the present application has high thermal and hydrothermal stability and high selectivity to branched hydrocarbons, and when used for catalytic cracking of heavy oil, it can provide higher heavy oil conversion activity, lower selectivity to coke, higher yield of gasoline, branched C4 -hydrocarbons, light oil and total liquid content and increased branched hydrocarbon content in the resulting gasoline compared to existing Y-type molecular sieves.

In a second aspect, the present application provides a process for producing a modified Y-type molecular sieve, comprising the steps of:

(1) contacting the NaY type molecular sieve with a solution of a soluble calcium salt and a soluble rare earth salt for an ion exchange reaction to produce a Y type molecular sieve containing calcium and a rare earth element having a reduced sodium content;

(2) subjecting the Y-type molecular sieve obtained in step (1) to calcination at a temperature of approximately 350-480°C in an atmosphere of approximately 30-90 vol. % steam for about 4.5-7 hours and optionally drying to obtain a Y-type molecular sieve with a reduced lattice constant; And

(3) contacting the Y-type molecular sieve obtained in step (2) with silicon tetrachloride gas to react at a weight ratio of SiCl ₄ to Y-type molecular sieve with a reduced lattice constant on a dry matter basis ranging from about 0.1: 1 to about 0.7:1 and a reaction temperature of about 200-650° C. for a reaction time of about 10 minutes to about 5 hours to produce a modified Y-type molecular sieve.

In some specific embodiments, the method comprises the steps of:

(1) contacting the NaY type molecular sieve with a solution of a soluble calcium salt and a soluble rare earth salt to carry out an ion exchange reaction, filtration and washing to obtain a Y type molecular sieve containing calcium and a rare earth element and having a normal lattice constant and a reduced sodium content;

(2) subjecting a Y-type molecular sieve containing calcium and a rare earth element and having a normal lattice constant and a reduced sodium content to modification, optionally drying, to obtain a Y-type molecular sieve of reduced lattice constant, wherein the modification includes calcining the Y-type molecular sieve, containing calcium and a rare earth element and having a normal lattice constant and a reduced sodium content, at approximately 350-480°C in an atmosphere containing approximately 30-90 vol. % steam (also called an atmosphere of approximately 30-90 vol.% steam or approximately 30-90 vol.% steam), for approximately 4.5-7 hours; And

(3) contacting the reduced lattice constant type Y molecular sieve with gaseous silicon tetrachloride to react at a weight ratio of SiCl ₄ to the reduced lattice constant type Y molecular sieve obtained in step (2), on a dry matter basis ranging from about 0.1:1 to about 0.7:1 and a reaction temperature of about 200-650°C for a reaction time of about 10 minutes to about 5 hours, and then washing and filtering to obtain a modified Y-type molecular sieve.

In some specific embodiments, the reduced lattice constant type Y molecular sieve used in step (3) has a water content of no more than about 1 wt. %. If the water content of the Y-type molecular sieve obtained after modification in step (2) (i.e., the Y-type molecular sieve obtained after calcination) is not more than about 1 mass. %, the Υ type molecular sieve can be directly used to contact silicon tetrachloride to carry out the reaction, and if the water content of the Y type molecular sieve obtained after calcination in step (2) is more than 1 wt. %, the reduced lattice constant type Y molecular sieve obtained after calcination in step (2) is further dried to obtain a water content of less than about 1 wt. %.

In the method for producing a modified Y-type molecular sieve according to the present application, the contact in step (1) can be carried out by sequentially contacting the NaY-type molecular sieve with a soluble calcium salt solution and a soluble rare earth salt solution (for example, contacting first the rare earth salt solution and then with a calcium salt solution, or contacting first a calcium salt solution and then a rare earth salt solution) for ion exchange, or contacting a NaY type molecular sieve with a solution containing a soluble calcium salt and a soluble rare earth salt (also referred to herein as mixed solution of soluble calcium salt and soluble rare earth salt). A mixed solution of soluble calcium salt and soluble rare earth salt can be prepared by mixing the soluble calcium salt and soluble rare earth salt with a solvent such as water.

NaY type molecular sieve can be commercially available or prepared according to existing methods. In specific embodiments, the NaY-type molecular sieve has a lattice constant of approximately 2.465-2.472 nm, a silica-alumina lattice ratio (SiO ₂ /Al ₂ O ₃ molar ratio) of approximately 4.5-5.2, a relative crystallinity of approximately 85% or more, for example about 85-95%, and a sodium content of about 13.0-13.8 wt. % in terms of sodium oxide.

In the ion exchange reaction of step (1), the exchange temperature is preferably about 15-95°C, for example about 65-95°C, the exchange time is preferably about 30-120 minutes, for example about 45-90 minutes, weight ratio molecular sieve type NaY (in terms of dry matter): calcium salt (in terms of CaO): rare earth salt (in terms of RE ₂ O ₃ ): H ₂ O is approximately 1: 0.009-0.28: 0.005-0.09 :5-15. A rare earth salt is a soluble rare earth salt, and a calcium salt is a soluble calcium salt.

In a preferred embodiment, in the ion exchange reaction of step (1), NaY type molecular sieve, calcium salt, rare earth salt and water are mixed in a mass ratio of NaY type molecular sieve: calcium salt: rare earth salt: H ₂ O of approximately 1:0.009-0 .27:0.005-0.09:5-15 and the mixture is stirred at about 15-95°C, for example about 65-95°C, for preferably about 30-120 minutes to conduct ion exchange of calcium ion and rare earth ion with sodium ion. The water, for example, is deionized water, deionized water, or a mixture thereof. Mixing the NaY type molecular sieve, calcium salt, rare earth salt and water can be carried out by forming a suspension of the NaY type molecular sieve in water, and then adding a calcium salt and/or an aqueous solution of a calcium salt, a rare earth salt and/or an aqueous salt solution thereto. rare earth element.

In a preferred embodiment of the method according to the present application, the washing in step (1) is intended to wash out the exchanged sodium ions, for example, using deionized water or deionized water. Preferably, the Y-type molecular sieve containing calcium and a rare earth element and having a normal lattice constant and a reduced sodium content obtained in step (1) has a calcium content of about 0.3 to 10 mass. %, for example approximately 0.9-9 wt. %, approximately 0.4-6 wt. %, approximately 1-5 wt. %, approximately 2-4 wt. %, approximately 0.3-4 wt. %, approximately 3-6 wt. %, approximately 3.5-5.5 wt. % or approximately 4-9 wt. %, in terms of CaO; rare earth element content is approximately 2-8 wt. %, approximately 2.1-7 wt. %, approximately 3-7 wt. % or approximately 4-6 wt. % in terms of Re ₂ O ₃ ; sodium content is not more than about 9 wt. %, for example approximately 5.0-8.5 wt. % or approximately 5.5-7.5 wt. %, in terms of sodium oxide and the crystal lattice constant is approximately 2.465-2.472 nm.

In a preferred embodiment of the method according to the present application, the firing conditions of stage (2) include: firing temperature of approximately 380-460°C, firing atmosphere of approximately 40-80 vol. % steam and firing time approximately 5-6 hours.

In a preferred embodiment of the method according to this application, the steam atmosphere contains approximately 30-90 vol. %, preferably approximately 40-80 vol. %, steam and may also contain other gases such as one or more of air, helium or nitrogen.

In a preferred embodiment of the method of the present application, the reduced lattice constant type Y molecular sieve obtained in step (2) has a lattice constant of approximately 2.450-2.462 nm.

In a preferred embodiment of the method according to the present application, step (2) also involves drying the calcined molecular sieve to obtain a Y-type molecular sieve with reduced lattice constant, which has a water content of preferably no more than about 1 wt. %.

In a preferred embodiment of the process of the present application in step (3), the weight ratio of SiCl ₄ : Y molecular sieve (on a dry matter basis) is about 0.3:1 to about 0.6:1 and the reaction temperature is about 350 -500°C.

In a preferred embodiment of the method according to the present application, step (3) may also include washing the resulting modified Y-type molecular sieve with water. Washing can be carried out by a conventional washing method using water, such as deionized water or deionized water, to remove soluble by-products such as Na ⁺ , Cl ^- , Al ³⁺ and the like remaining in the molecular sieve. For example, washing conditions may include: a wash water to molecular sieve weight ratio of about 5-20:1, such as about 6-15:1, a pH of about 2.5-5.0, and a wash temperature of about 30-60°C. Preferably, the washing is carried out to such an extent that no free ions such as Na ⁺ , Cl ^- and Al ³⁺ can be detected in the spent washing liquid, and usually the content of each of the Na ⁺ , Cl ^- and Al ³⁺ ions in the spent washing liquid is is no more than about 0.05 wt. %.

In a preferred embodiment of the method according to the present application, the method for producing a modified type Y molecular sieve according to the present application comprises the steps of:

(1) contacting the NaY type molecular sieve (also called NaY type zeolite) with a mixed solution of soluble calcium salt and rare earth salt for ion exchange reaction, filtration and washing to obtain a Y type molecular sieve containing calcium and rare earth element and having a normal crystal constant lattice and reduced sodium content, and the specified ion exchange is carried out under stirring at a temperature of about 15-95°C, preferably about 65-95°C, for about 30-120 minutes;

(2) subjecting a Y-type molecular sieve containing calcium and a rare earth element and having a normal lattice constant and reduced sodium content to calcination at a temperature of approximately 350-480° C. in an atmosphere containing approximately 30-90 vol. % steam for about 4.5-7 hours and drying to obtain a Y-type molecular sieve having a reduced lattice constant and a water content of less than about 1 wt. %, and the lattice constant of the Y-type molecular sieve having a reduced lattice constant is approximately 2,450-2,462 nm; And

(3) contacting a Y-type molecular sieve with a reduced lattice constant and a water content of less than about 1 wt. % with gaseous SiCl ₄ evaporated by heating, to react at a weight ratio of SiCl ₄ to a Y-type molecular sieve with a reduced lattice constant (on a dry matter basis) of from about 0.1:1 to about 0.7:1 and temperature about 200-650°C for about 10 minutes to about 5 hours, washing and filtering to obtain a modified Y-type molecular sieve.

The method for producing a modified Y type molecular sieve containing calcium and a rare earth element according to the present application can be used to produce high silica content Y type molecular sieves with high crystallinity, high thermal stability, high hydrothermal stability and a defined secondary pore structure. The resulting calcium and rare earth molecular sieve has a uniform distribution of aluminum and a low content of non-lattice aluminum. When used for catalytic cracking of heavy oil, the modified Y type molecular sieve shows good coke selectivity and high cracking activity for heavy oil, and can achieve improved yields of gasoline, branched C4 hydrocarbons, liquefied gas, light oil and total liquid content, as well as increased branched hydrocarbons in gasoline.

In a third aspect, the present application provides a modified Y-type molecular sieve obtained by the method for producing a modified Y-type molecular sieve according to the present application.

In a fourth aspect, the present application provides a catalytic cracking catalyst containing approximately 10-50 wt. % based on dry matter of the modified molecular sieve type Y according to this application, approximately 10-40 wt. % of alumina-based binder in terms of aluminum oxide and approximately 10-80 wt. % based on clay dry matter based on the weight of the catalytic cracking catalyst.

In some embodiments, the catalytic cracking catalyst of the present application may also contain an additional molecular sieve other than a modified Y-type molecular sieve, and the additional molecular sieve may be present in an amount on a dry matter basis of approximately 0-40 weight percent. %, for example approximately 0-30 wt. % or approximately 1-20 wt. %, based on the mass of the catalyst. The additional molecular sieve may be selected from a variety of molecular sieves useful in catalytic cracking catalysts, such as one or more of MFI zeolites, beta zeolite, other Y-type zeolites, and non-zeolitic molecular sieves. Preferably, the additional Y-type molecular sieve is present in an amount on a dry matter basis of no more than about 40 weight percent. %, for example approximately 1-40 wt. % or approximately 0-20 wt. %. The optional Y-type molecular sieve may be, for example, one or more of REY, REHY, DASY, SOY and PSRY; The MFI structured zeolite may be, for example, one or more of HZSM-5, ZRP and ZSP; the beta zeolite may be, for example, a Ηβ zeolite; and the non-zeolite molecular sieve may be, for example, one or more of aluminophosphate molecular sieves (A1PO molecular sieves) and silicoaluminophosphate molecular sieves (SAPO molecular sieves).

In a preferred embodiment of the catalyst according to the present application, the modified Y-type molecular sieve is present in an amount on a dry matter basis of approximately 15-45 wt. %, for example approximately 25-40 wt. %.

In the catalytic cracking catalyst of the present application, the clay can be selected from various clays suitable for use as a component in catalytic cracking catalysts that are well known to those skilled in the art, such as one or more of kaolin, hydrated halloysite, montmorillonite, diatomite, halloysite, saponite , rector, sepiolite, attapulgite, hydrotalcite and bentonite. Preferably, the clay is present in the catalytic cracking catalyst of the present application in an amount on a dry matter basis of approximately 20-55 wt. % or approximately 30-50 wt. %.

In a preferred embodiment, the catalytic cracking catalyst contains 25-40 wt. % in terms of dry matter of the modified molecular sieve type Y, 20-35 wt. % of alumina-based binder in terms of aluminum oxide and 30-50 wt. % in terms of clay dry matter.

In the catalytic cracking catalyst of the present application, the alumina binder is preferably present in an amount of about 20-35 wt. %. According to the present application, the alumina binder may be one or more selected from the group consisting of various forms of alumina, hydrated alumina and alumina sol commonly used in catalytic cracking catalysts. For example, it may be one or more selected from the group consisting of γ-alumina, η-alumina, θ-alumina, χ-alumina, pseudoboehmite, boehmite, gibbsite, bayerite and aluminum sol, preferably pseudoboehmite and sol aluminum For example, the catalytic cracking catalyst may contain approximately 2-15 wt. %, preferably approximately 3-10 wt. %, aluminum sol in terms of aluminum oxide and approximately 10-30 wt. %, preferably approximately 15-25 wt. %, pseudoboehmite in terms of aluminum oxide.

The catalytic cracking catalyst of the present application can be produced by conventional methods, for example, can be produced according to existing methods such as those described in Chinese Patent Application Publication CN 1098130 A, CN 1362472 A. The production method generally involves the steps of forming a suspension containing a modified a Y molecular sieve, a binder, clay and water, spray drying, and optionally washing and drying, all of the steps of spray drying, washing and drying being known in the art and not specifically required herein.

In a fifth aspect, the present application provides a method for producing a catalytic cracking catalyst comprising the steps of: providing a modified Y-type molecular sieve according to the present application, forming a slurry containing the modified Y-type molecular sieve, an alumina binder, clay and water, and spray drying.

In a sixth aspect, the present application provides the use of the modified Y-type molecular sieve of the present application in the catalytic cracking of hydrocarbon oils by contacting the hydrocarbon oil with a catalytic cracking catalyst containing the modified Y-type molecular sieve of the present application.

In a seventh aspect, the present application provides a catalytic cracking process comprising the step of contacting a heavy oil feedstock with a catalytic cracking catalyst of the present application to react under conditions for cracking the heavy oil in a fluidized bed of the catalyst.

In the catalytic cracking process of the present application, the heavy oil may be any heavy hydrocarbon oil feedstock known in the art, such as one or more of vacuum gas oil, fuel oil, tar, and deasphalted heavy oil.

In the catalytic cracking process of the present application, the reaction conditions for fluidized-bed cracking of heavy oil may be those generally used in the art and may, for example, include: reaction temperature of about 480-530° C., reaction time of about 1-10 seconds and a catalyst to oil weight ratio of from about 3:1 to about 20:1.

In some preferred embodiments, the present application provides the following technical solutions.

A1. A modified Y-type molecular sieve having a calcium content of approximately 0.3-4 wt. % in terms of calcium oxide (CaO), the rare earth element content is approximately 2-7 wt. % in terms of rare earth oxide (RE ₂ O ₃ ) and a sodium content of no more than approximately 0.5 wt. % in terms of sodium oxide (Na ₂ O) in terms of dry matter and based on the weight of the specified modified molecular sieve type Y; total pore volume approximately 0.33-0.39 ml/g, ratio of secondary pore volume with pore size 2-100 nm to total pore volume approximately 10-25%, lattice constant approximately 2.440-2.455 nm, ratio of non-lattice aluminum content to a total aluminum content of not more than about 20%, a lattice breakdown temperature of not less than about 1050° C., and a ratio of acid B to acid L in a total acid content of not less than about 2.30, as determined by infrared spectroscopy of adsorbed pyridine at 200 °C.

A2. The modified Y-type molecular sieve according to claim A1, having a ratio of secondary pore volume with a pore size of 2-100 nm to total pore volume of approximately 15-21%, preferably approximately 17-21%.

A3. Modified molecular sieve type Y according to claims. A1 or A2 having a non-lattice aluminum to total aluminum content ratio of approximately 13-19% and a silica-alumina lattice ratio of approximately 7.3-14, calculated as the SiO ₂ /Al ₂ O ₃ molar ratio.

A4. A modified Y-type molecular sieve according to any one of the preceding claims, having a lattice breakdown temperature of about 1050-1080°C or about 1050-1063°C.

A5. The modified Y-type molecular sieve of any one of the preceding claims, having a ratio of acid B to acid L in a total acid content of about 2.3-5.0, about 2.4-4.2, or about 2.4-3.5, such that determined using infrared spectroscopy of adsorbed pyridine at 200°C.

A6. The modified Y-type molecular sieve of any one of the preceding claims, wherein the modified Y-type molecular sieve is characterized by maintaining a relative crystallinity of about 35% or more, such as about 36-45% or about 35-48%, after aging at 800° C. under atmospheric pressure in an atmosphere of 100% steam for 17 hours.

A7. A modified Y-type molecular sieve according to any one of the preceding claims, having a relative crystallinity of approximately 58-68%.

A8. The modified Y-type molecular sieve according to any one of the preceding paragraphs, wherein the modified Y-type molecular sieve has a calcium content of approximately 0.5-3.5 wt. % in terms of calcium oxide (CaO), the rare earth element content is approximately 2.5-6.5 wt. % in terms of rare earth oxide (RE ₂ O ₃ ), sodium content is approximately 0.2-0.5 wt. % in terms of sodium oxide (Na ₂ O), a lattice constant of approximately 2.442-2.452 nm and a silica-alumina lattice ratio calculated as the SiO ₂ /Al ₂ O ₃ molar ratio of approximately 8-12.6.

A9. The modified Y-type molecular sieve of any one of the preceding claims, wherein the modified Y-type molecular sieve has an O1s electron binding energy of no more than about 532.70 eV, such as about 532.55-532.65 eV.

A10. A method for producing a modified Y-type molecular sieve, comprising the steps of:

(1) contacting the NaY type molecular sieve with a solution of a soluble calcium salt and a soluble rare earth salt for an ion exchange reaction to produce a Y type molecular sieve containing calcium and a rare earth element having a reduced sodium content;

(2) subjecting the Y-type molecular sieve obtained in step (1) to calcination at a temperature of approximately 350-480°C in an atmosphere of approximately 30-90 vol. % steam for about 4.5-7 hours and optionally drying to obtain a Y-type molecular sieve with a reduced lattice constant; And

(3) contacting the Y-type molecular sieve obtained in step (2) with silicon tetrachloride gas to react at a weight ratio of SiCl ₄ to Y-type molecular sieve of a reduced lattice constant on a dry matter basis from about 0.1:1 to about 0.7:1 and a reaction temperature of about 200-650° C. for a reaction time of about 10 minutes to about 5 hours to produce a modified Y-type molecular sieve.

A11. The method of claim A10, wherein the Y-type molecular sieve obtained in step (1) has a lattice constant of about 2.465-2.472 nm and a sodium content of no more than about 8.8 wt. % in terms of sodium oxide.

A12. Method according to paragraphs. A10 or A11, in which the Y-type molecular sieve obtained in step (1) has a calcium content of approximately 0.3-10 wt. %, for example approximately 0.9-9 wt. %, in terms of calcium oxide (CaO), the rare earth element content is approximately 2-8 wt. %, for example, approximately 2.1-7 wt. %, in terms of rare earth oxide (RE ₂ O ₃ ), sodium content is approximately 4-8.8 wt. %, for example approximately 5.0-8.5 wt. %, in terms of sodium oxide (Na ₂ O) and the crystal lattice constant is approximately 2.465-2.472 nm.

A13. The method according to any one of paragraphs. A10-A12, in which, in step (1), NaY type molecular sieve, soluble calcium salt, soluble rare earth salt and water are mixed in a mass ratio of NaY type molecular sieve: soluble calcium salt: soluble rare earth salt: H ₂ O of approximately 1: 0.009-0.28:0.005-0.09:5-15 for ion exchange.

A14. The method according to any one of paragraphs. A10 to A13, wherein in step (1), a NaY type molecular sieve is mixed with water, and a soluble calcium salt and/or a soluble calcium salt solution and a soluble rare earth salt and/or a soluble rare earth salt solution are added with stirring to carry out an ion exchange reaction. ;

conditions for the ion exchange reaction include: an exchange temperature of approximately 15-95°C and an exchange time of approximately 30-120 minutes;

preferably the soluble calcium salt solution and the soluble rare earth salt solution are an aqueous soluble calcium salt solution and an aqueous soluble rare earth salt solution, and/or

preferably, the soluble calcium salt is calcium chloride and/or calcium nitrate, and the soluble rare earth salt is a rare earth chloride and/or a rare earth nitrate.

A15. The method according to any one of paragraphs. A10-A14, in which in step (2) the firing temperature is approximately 380-460°C, the firing atmosphere is an atmosphere of approximately 40-80 vol. % steam, and the firing time is approximately 5-6 hours.

A16. The method according to any one of paragraphs. A10-A15, in which the Y-type molecular sieve with reduced lattice constant obtained in step (2) has a lattice constant of about 2,450-2,462 nm and a water content of not more than about 1 mass. %.

A17. The method according to any one of paragraphs. A10-A16, wherein step (3) further comprises washing the resulting modified Y-type molecular sieve with water under washing conditions which include: molecular sieve:H ₂ O ratio of about 1:5-20, pH of about 2.5-5.0 and a washing temperature of approximately 30-60°C.

A18. A modified Y-type molecular sieve obtained by the method according to any one of paragraphs. A10-A17.

A19. A catalytic cracking catalyst containing approximately 10-50 wt. % based on dry matter of the modified molecular sieve type Y, approximately 10-40 wt. % in terms of aluminum oxide binder based on aluminum oxide and approximately 10-80 wt. % in terms of clay dry matter; wherein the modified Y-type molecular sieve is a modified Y-type molecular sieve according to any one of claims. A1-A9 and A18.

A20. The use of a modified Y-type molecular sieve according to any one of paragraphs. A1-A9 and A18 in the catalytic cracking of hydrocarbon oils, comprising the stage of contacting the hydrocarbon oil with a catalytic cracking catalyst containing a modified Y-type molecular sieve according to any one of paragraphs. A1-A9 and A18.

IN 1. A modified Y-type molecular sieve having a calcium oxide content of approximately 0.3-4 wt. %, rare earth oxide content is approximately 2-7 wt. %, sodium oxide content is not more than approximately 0.5 wt. %, total pore volume approximately 0.33-0.39 ml/g, ratio of secondary pore volume with pore size 2-100 nm to total pore volume approximately 10-25%, lattice constant approximately 2.440-2.455 nm, ratio of non-lattice content aluminum to total aluminum content of not more than about 20%, a lattice breakdown temperature of not less than about 1050° C., and a ratio of acid B to acid L in the total acid content of not less than about 2.30, as determined by infrared spectroscopy of adsorbed pyridine at 200°C.

B2. The modified Y-type molecular sieve of claim B1, wherein the modified Y-type molecular sieve has a secondary pore volume ratio of 2-100 nm pore size to total pore volume of approximately 15-21%.

B3. The modified Y-type molecular sieve of claim B1, wherein the modified Y-type molecular sieve has a non-lattice aluminum to total aluminum content ratio of approximately 13-19% and a silica-alumina lattice ratio of approximately 7.3-14, calculated as molar SiO ₂ /Al ₂ O ₃ ratio.

B4. The modified Y-type molecular sieve according to claim B1, wherein the modified Y-type molecular sieve has a lattice breakdown temperature of approximately 1050-1080°C or 1050-1063°C.

B5. The modified Y-type molecular sieve of claim B1, wherein the Y-type modified molecular sieve has an acid B to acid L ratio of a total acid content of about 2.3-5.0, or 2.4-4.2, or 2.4- 3.5, which was determined using infrared spectroscopy of adsorbed pyridine at 200°C.

B6. The modified Y-type molecular sieve of claim B1, wherein the modified Y-type molecular sieve is characterized by maintaining a relative crystallinity of about 35% or more, such as about 36-45% or 35-48%, after aging at 800° C. under atmospheric pressure in an atmosphere 100% steam for 17 hours.

B7. The modified Y-type molecular sieve of claim B1, wherein the modified Y-type molecular sieve has a relative crystallinity of approximately 58-68%.

B8. Modified Y-type molecular sieve according to any one of paragraphs. B1-B7, wherein the modified Y-type molecular sieve has a calcium oxide content of approximately 0.3-4 wt. %, rare earth oxide content is approximately 2-7 wt. %, sodium oxide content approximately 0.2-0.5 wt. %, a lattice constant of approximately 2.442-2.452 nm and a silica-alumina lattice ratio of approximately 8-12.6.

B9. A method for producing a modified Y-type molecular sieve, comprising the steps of:

(1) contacting a NaY type molecular sieve with a solution of a soluble calcium salt and a soluble rare earth salt for an ion exchange reaction, filtering, washing and optionally drying to obtain a Y type molecular sieve containing calcium and a rare earth element and having a normal lattice constant and a reduced content sodium oxide;

(2) subjecting the above Y-type molecular sieve containing calcium and a rare earth element and having a normal lattice constant and a reduced sodium oxide content to calcination at a temperature of about 350-480° C. in an atmosphere of about 30-90 vol. % steam for approximately 4.5-7 hours, optionally drying, to obtain a Y-type molecular sieve with a reduced lattice constant; And

(3) contacting the reduced lattice constant type Y molecular sieve with gaseous silicon tetrachloride to react at a weight ratio of SiCl ₄ to reduced lattice constant type Y molecular sieve on a dry matter basis of from about 0.1:1 to about 0, 7:1 and a reaction temperature of about 200-650° C. for a reaction time of about 10 minutes to about 5 hours, washing and filtering to obtain a modified Y-type molecular sieve.

AT 10 O'CLOCK. The method of claim B9, wherein the Y-type molecular sieve containing calcium and a rare earth element and having a normal lattice constant and a reduced sodium oxide content obtained in step (1) has a lattice constant of approximately 2.465-2.472 nm and a sodium oxide content no more than about 8.8 wt. %.

AT 11. The method according to claim B9, wherein in step (1) the Y-type molecular sieve containing calcium and a rare earth element and having a normal lattice constant and a reduced sodium oxide content has a calcium content of approximately 0.4-10 wt. % in terms of CaO, the rare earth element content is approximately 2-8 wt. % in terms of RE ₂ O ₃ , sodium oxide content is approximately 4-8.8 wt. %, for example approximately 5.5-8.5 wt. %, and a lattice constant of approximately 2.465-2.472 nm.

AT 12. The method according to claim B9, wherein step (1) of contacting the NaY type molecular sieve with a solution of soluble calcium salt and soluble rare earth salt for an ion exchange reaction is carried out by mixing the NaY type molecular sieve, soluble calcium salt, soluble rare earth salt and water in on a mass basis molecular sieve type NaY: soluble calcium salt: soluble rare earth salt: H ₂ O approximately 1:0.009-0.28:0.005-0.09:5-15 and stirring.

B13. Method according to paragraphs. B9 or B12, in which step (1) of contacting the NaY type molecular sieve with a solution of soluble calcium salts and a soluble rare earth salt for an ion exchange reaction involves: mixing the NaY type molecular sieve with water, adding a soluble calcium salt and/or a soluble calcium salt solution and a soluble rare earth salt and/or a soluble rare earth salt solution while stirring for an ion exchange reaction, filtering and washing; conditions for the ion exchange reaction include: an exchange temperature of about 15-95° C. and an exchange time of about 30-120 minutes, the soluble calcium salt solution and the soluble rare earth salt solution being aqueous solutions of the soluble calcium salt and the soluble rare earth salt; and the soluble calcium salt is, for example, calcium chloride and/or calcium nitrate, and the soluble rare earth salt is, for example, a rare earth chloride and/or a rare earth nitrate.

B14. The method according to claim B9, in which in step (2) the firing temperature is approximately 380-460°C, the firing atmosphere is an atmosphere of approximately 40-80 vol. % steam, and the firing time is approximately 5-6 hours.

B15. The method of claim B9, wherein the Y-type molecular sieve with reduced lattice constant obtained in step (2) has a lattice constant of about 2,450-2,462 nm and a water content of not more than about 1 wt. %.

B16. The method of claim B9, wherein the washing of step (3) is carried out by washing with water under conditions including a molecular sieve:H ₂ O ratio of about 1:6-15, a pH of about 2.5-5.0 and a washing temperature of about 30- 60°C.

C1. Catalytic cracking catalyst containing 10-50 wt. % based on dry matter of modified molecular sieve type Y, 10-40 wt. % of alumina-based binder in terms of aluminum oxide and 10-80 wt. % in terms of clay dry matter; wherein the modified Y-type molecular sieve has a calcium oxide content of approximately 0.3-4 wt. %, rare earth oxide content is approximately 2-7 wt. %, sodium oxide content is not more than approximately 0.5 wt. %, total pore volume approximately 0.33-0.39 ml/g, ratio of secondary pore volume with pore size 2-100 nm to total pore volume approximately 10-25%, lattice constant approximately 2.440-2.455 nm, ratio of non-lattice content aluminum to total aluminum content of not more than about 20%, a lattice breakdown temperature of not less than about 1050° C., and a ratio of acid B to acid L in the total acid content of not less than about 2.30, as determined by infrared spectroscopy of adsorbed pyridine at 200°C.

C2. The catalytic cracking catalyst according to claim C1, in which the modified Y-type molecular sieve has a pore volume ratio of secondary pores with a pore size of 2-100 nm to the total pore volume of approximately 15-21%, a ratio of non-lattice aluminum content to total aluminum content of approximately 13-19 %, the ratio of silicon dioxide-alumina in the crystal lattice is approximately 7.3-14, which is calculated as the molar ratio of SiO ₂ /Al ₂ O ₃ , the temperature of destruction of the crystal lattice is approximately 1050-1080 ° C, for example, approximately 1050-1063 ° C , and the ratio of acid B to acid L in the total acid content is approximately 2.4-4.2, as determined by infrared spectroscopy with pyridine absorption at 200°C.

C3. The catalytic cracking catalyst according to claim C1, wherein the modified Y-type molecular sieve is characterized by maintaining a relative crystallinity of about 35% or more, for example, about 36-45%, after severe aging at 800° C. under atmospheric pressure in an atmosphere of 100% steam for 17 o'clock.

C4. The catalytic cracking catalyst according to claim C1, wherein the modified Y-type molecular sieve has a relative crystallinity of approximately 58-68%.

C5. Catalytic cracking catalyst according to any one of paragraphs. C1-C4, in which the modified Y-type molecular sieve has a calcium oxide content of approximately 0.3-4 wt. %, rare earth oxide content is approximately 2-7 wt. %, sodium oxide content approximately 0.2-0.5 wt. %, a lattice constant of approximately 2.442-2.452 nm and a silica-alumina lattice ratio of approximately 8-12.6.

C6. A method of producing a catalytic cracking catalyst, comprising the steps of preparing a modified Y-type molecular sieve, forming a slurry containing the modified Y-type molecular sieve, an alumina binder, clay and water, and spray drying, wherein the modified Y-type molecular sieve is produced by a method comprising the steps of: :

(1) contacting a NaY type molecular sieve with a solution of a soluble calcium salt and a soluble rare earth salt for an ion exchange reaction, filtering, washing and optionally drying to obtain a Y type molecular sieve containing calcium and a rare earth element and having a normal lattice constant and a reduced content sodium oxide;

(2) subjecting the above Y-type molecular sieve containing calcium and a rare earth element and having a normal lattice constant and a reduced sodium oxide content to calcination at a temperature of about 350-480° C. in an atmosphere of about 30-90 vol. % steam for approximately 4.5-7 hours, optionally drying, to obtain a Y-type molecular sieve with a reduced lattice constant;

(3) contacting the reduced lattice constant type Y molecular sieve with gaseous silicon tetrachloride to react at a weight ratio of SiCl ₄ to reduced lattice constant type Y molecular sieve on a dry matter basis of from about 0.1:1 to about 0, 7:1 and a reaction temperature of about 200-650° C. for a reaction time of about 10 minutes to about 5 hours, washing and filtering to obtain a modified Y-type molecular sieve.

C7. The method of claim C6, wherein the Y-type molecular sieve containing calcium and a rare earth element and having a normal lattice constant and a reduced sodium oxide content obtained in step (1) has a lattice constant of approximately 2.465-2.472 nm and a sodium oxide content no more than 8.8 wt. %; the reduced lattice constant type Y molecular sieve obtained in step (2) has a lattice constant of about 2,450-2,462 nm and a water content of no more than about 1 wt. %.

C8. The method according to claim C7, wherein in step (1) the Y-type molecular sieve containing calcium and a rare earth element and having a normal lattice constant and a reduced sodium oxide content has a calcium content of approximately 0.4-3.9 wt. % in terms of CaO, the rare earth element content is approximately 2-7 wt. % in terms of RE ₂ O ₃ and the sodium oxide content is approximately 4-8.8 wt. %, for example approximately 5.5-8.5 wt. %, and a lattice constant of approximately 2.465-2.472 nm.

C9. The method according to claim C6, wherein step (1) of contacting the NaY type molecular sieve with a solution of soluble calcium salt and soluble rare earth salt for an ion exchange reaction is carried out by mixing the NaY type molecular sieve, soluble calcium salt, soluble rare earth salt and water in mass ratio molecular sieve type NaY: soluble calcium salt: soluble rare earth salt: H ₂ O approximately 1:0.009-0.28:0.005-0.09:5-15 and stirring.

C10. Method according to paragraphs. C6 or C9, in which step (1) of contacting the NaY type molecular sieve with a solution of soluble calcium salt and soluble rare earth salt for an ion exchange reaction involves: mixing the NaY type molecular sieve with water, adding soluble calcium salt and/or soluble calcium salt solution and a soluble rare earth salt and/or a solution of a soluble rare earth salt while stirring to carry out an ion exchange reaction, filtering and washing; conditions for the ion exchange reaction include: an exchange temperature of approximately 15-95°C and an exchange time of approximately 30-120 minutes; wherein the soluble calcium salt solution and the soluble rare earth salt solution are aqueous solutions of a soluble calcium salt and a soluble rare earth salt; the soluble calcium salt is, for example, calcium chloride and/or calcium nitrate, and the soluble rare earth salt is, for example, a rare earth chloride and/or a rare earth nitrate.

C11. The method according to claim C6, in which in step (2) the firing temperature is approximately 380-460°C, the firing atmosphere is an atmosphere of approximately 40-80 vol. % steam, and the firing time is approximately 5-6 hours.

C12. The method of claim C6, wherein the washing of step (3) is carried out by washing with water under conditions including a molecular sieve:H ₂ O ratio of about 1:6-15, a pH of about 2.5-5.0, and a washing temperature of about 30 -60°C.

C13. A catalytic cracking method comprising the step of contacting heavy oil with a catalytic cracking catalyst under FCC conditions, wherein the catalytic cracking catalyst is a catalytic cracking catalyst according to any one of claims. C1-C5; and FCC conditions include, for example: reaction temperature approximately 480-530°C, reaction time 1-10 seconds, catalyst to oil weight ratio 3-20 1.

Examples

The present application will be further illustrated by the following examples, without limiting the present application, however.

Raw Materials: In the following examples and comparative examples, NaY type molecular sieves are supplied by Qilu Division of Sinopec Catalyst Co., Ltd., whose sodium content is 13.5 mass. % based on sodium oxide, the silica-alumina lattice ratio (SiO ₂ /Al ₂ O ₃ molar ratio) is 4.6, the lattice constant is 2.470 nm, and the relative crystallinity is 90%; Calcium chloride and calcium nitrate are chemically pure reagents produced by Sinopharm Chemical Reagent Co., Ltd. (Hushi); Rare earth chloride and rare earth nitrate are chemically pure reagents produced by Beijing Chemical Works; pseudoboehmite is an industrial product produced by Shandong Aluminum Smelter, with a solid content of 61 wt. %; kaolin is a specialty kaolin for cracking catalysts manufactured by China Kaolin Clay Co., Ltd., of Suzhou, with a solids content of 76 wt. %; aluminum sol is supplied by Qilu Division of Sinopec Catalyst Co., Ltd., with an aluminum oxide content of 21 wt. %.

Unless otherwise stated, the reagents used in each of the comparative examples and examples were chemically pure reagents.

Analytical Method: In each of the comparative examples and examples, the element content of the molecular sieve was determined using X-ray fluorescence spectrometry; The lattice constant and relative crystallinity of the molecular sieve were determined using X-ray powder diffractometry (XRD) according to the standard method RIPP 145-90, RIPP 146-90 (see "Petrochemical Analysis Methods (RIPP Test Methods)", edited by Cuiding YANG et al. , Science Press, September 1990, First Edition, pp. 412-415), the silica-alumina ratio in the molecular sieve lattice was calculated according to the following equation:

where a ₀ refers to the lattice constant, the unit of which is nm.

The total silica-alumina ratio of the molecular sieve was calculated based on the Si and Al elemental contents determined by X-ray fluorescence spectrometry. The ratio of lattice Al content to total Al content was calculated based on the lattice silica-alumina ratio determined by XRD and the total silica-alumina ratio determined by XRF, and then the ratio of non-lattice Al content to total Al content. The lattice failure temperature was determined using differential thermal analysis (DTA).

In each of the comparative examples and examples, the type of acid site of the molecular sieve and the acid content thereof were determined by infrared spectroscopy of adsorbed pyridine. The instrument was an IFS113V FT-IR (Fourier transform infrared) spectrometer from Bruker Company, USA. The method for determining the acid content using infrared spectroscopy of adsorbed pyridine at 200°C was as follows: a self-supporting sample plate was placed in the in-situ cell of the infrared spectrometer and sealed; the sample was heated to a temperature of 400°C, evacuated to 10 ^-3 Pa and kept at the temperature for 2 hours to remove gas molecules adsorbed by the sample; the sample was cooled to room temperature, pyridine vapor was introduced at a pressure of 2.67 Pa, and the sample was kept under these conditions for 30 minutes to achieve adsorption equilibrium; then the sample was heated to a temperature of 200°C and vacuumed to 10 ^-3 Pa for desorption for 30 minutes; After this, the sample was cooled to room temperature and subjected to spectral analysis in the scanning wavenumber range from 1400 cm ^-1 to 1700 cm ^-1 , and an infrared spectrum of pyridine adsorption of the sample desorbed at 200°C was obtained. The relative amounts of all Brønsted acid sites (B acid sites) and Lewis acid sites (L acid sites) in the molecular sieve were obtained based on the intensities of the characteristic absorption peaks at 1540 cm ^-1 and 1450 cm ^-1 in the infrared light spectrum of the adsorbed pyridine.

In each of the comparative examples and examples, the secondary pore volume was determined as follows: according to the standard method RIPP 151-90 (see "Petrochemical Analysis Methods (RIPP Test Methods)", Cuiding YANG et al., Science Press, September 1990, First Edition, pp. 424-426) the total pore volume of the molecular sieve was determined based on the adsorption isotherm, and then the micropore volume of the molecular sieve was determined based on 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.

In each of the Comparative Examples and Examples, the electron binding energy Ols of the molecular sieve was determined as follows: The XPS test was performed on an ESCALab 250 X-ray photoelectron spectrometer from Thermo Fisher. The excitation source was a monochromatic X-ray beam Α1 Κα with an energy of 1486.6 eV and a power of 150 W. The penetration energy for narrow scans was 30 eV. The base vacuum at the time of analysis was approximately 6.5 x 10 ^-10 mbar. The binding energy was calibrated according to the C1s peak (284.8 eV) of the alkyl carbon or contaminated carbon. The processing software was Avantage 5.952, originally installed in the instrument. The binding energy value was determined based on the obtained XPS data.

Example 1

2000 g of molecular sieve of the NaY type (in terms of dry matter) were added to 20 l of water purified from cations and mixed evenly with stirring, 345 ml of Ca(NO ₃ ) ₂ solution (with a concentration of 248 g/l in terms of CaO) was added. then 300 ml of RE(NO ₃ ) ₃ solution (with a concentration of 319 g/l in terms of RE ₂ O ₃ ) was added and the mixture was stirred, heated to a temperature of 90-95°C and kept for 1 hour. The mixture was then filtered and washed, and the filter cake was dried at 120°C to obtain a Y-type molecular sieve with a lattice constant of 2.471 nm, sodium content of 6.6 wt. % in terms of sodium oxide, calcium content 4.9 wt. % in terms of CaO and a rare earth element content of 4.4 wt. % in terms of RE ₂ O ₃ . Then the resulting product was fired at 390°C in an atmosphere containing 50 vol. % steam and 50 vol. % air, for 6 hours to obtain a Y-type molecular sieve with a lattice constant of 2.455 nm, and then dried to obtain a water content of less than 1 wt. %. After this, gaseous SiCl ₄ , evaporated by heating, was introduced at a mass ratio of SiCl ₄ : molecular sieve type Y (in terms of dry matter) of 0.5: 1, reacted at 400 ° C for 2 hours, then washed with 20 l of cation-free water and filtered to obtain a modified Y type molecular sieve of the present application, designated SZ1, the physicochemical properties of which are shown in Table 1.

After aging SZ1 in an unprotected state at 800°C under atmospheric pressure in an atmosphere of 100% steam for 17 hours, the relative crystallinity of the molecular sieve SZ1 before and after aging was analyzed by XRD, and the retention of relative crystallinity after aging was calculated. The results are shown in Table 2, in which:

Example 2

2000 g of NaY type molecular sieve (in terms of dry matter) was added to 25 l of cation-free water and mixed evenly with stirring, 368 ml of CaCl ₂ solution (with a concentration of 248 g/l in terms of CaO) was added, then 400 ml was added RECl ₃ solution (with a concentration of 319 g/l in terms of RE ₂ O ₃ ) and the mixture was stirred, heated to a temperature of 90-95°C and kept for 1 hour. The mixture was then filtered and washed, and the filter cake was dried at 120°C to obtain a Y-type molecular sieve with a lattice constant of 2.471 nm, sodium content of 5.2 wt. % in terms of sodium oxide, calcium content 8.7 wt. % in terms of CaO and a rare earth element content of 5.7 wt. % in terms of RE ₂ O ₃ . The resulting product was then roasted at 450°C under 80% steam for 5.5 hours to obtain a Y-type molecular sieve with a lattice constant of 2.461 nm, and then dried to obtain a water content of less than 1 wt. %. After this, gaseous SiCl ₄ , evaporated by heating, was introduced at a mass ratio of SiCl ₄ : molecular sieve type Y 0.6:1, reacted at 480°C for 1.5 hours, then washed with 20 L of cation-free water and filtered to obtain a modified Y-type molecular sieve designated as SZ2, the physicochemical properties of which are shown in Table 1.

After aging SZ2 in an unprotected state at 800°C under atmospheric pressure in an atmosphere of 100% steam (i.e. aged in an atmosphere of 100% steam for 17 hours), the crystallinity of the SZ2 molecular sieve before and after aging was analyzed by XRD and the retention was calculated relative crystallinity after aging. The results are presented in Table 2.

Example 3

2000 g of NaY molecular sieve (in terms of dry matter) was added to 22 l of cation-free water and mixed evenly with stirring, 214 ml of CaCl ₂ solution (with a concentration of 248 g/l in terms of CaO) was added, then 285 ml were added RECl ₃ solution (with a concentration of 319 g/l in terms of RE ₂ O ₃ ) and the mixture was stirred, heated to a temperature of 90-95°C and kept for 1 hour with stirring. The mixture was then filtered and washed, and the filter cake was dried at 120°C to obtain a Y-type molecular sieve with a lattice constant of 2.471 nm, sodium content of 7.2 wt. % in terms of sodium oxide, calcium content 3.8 wt. % in terms of CaO and a rare earth element content of 4.7 wt. % in terms of RE ₂ O ₃ . The resulting product was then calcined at 450°C in an 80% steam atmosphere for 5 hours to obtain a Y-type molecular sieve with a lattice constant of 2.458 nm, and then dried to obtain a water content of less than 1 mass. %. After this, gaseous SiCl ₄ , evaporated by heating, was introduced at a mass ratio of SiCl ₄ : molecular sieve type Y 0.4:1, reacted at 500°C for 1 hour, then washed with 20 l of cation-free water and filtered to obtain a modified Y-type molecular sieve designated as SZ3, the physicochemical properties of which are shown in Table 1.

After aging SZ3 in an unprotected state at 800° C. under atmospheric pressure in a 100% steam atmosphere, the crystallinity of the SZ3 molecular sieve before and after aging was analyzed by XRD, and the retention of relative crystallinity after aging was calculated. The results are presented in Table 2.

Comparative example 1

2000 g of molecular sieve of the NaY type (in terms of dry matter) were added to 20 l of water purified from cations, mixed evenly with stirring, 1000 g of (NH ₄ ) ₂ SO ₄ were added and the mixture was stirred, heated to a temperature of 90-95 ° C and kept for 1 hour. Then, after filtration and washing, the filter cake was dried at 120°C and then subjected to hydrothermal treatment by firing at 650°C in an atmosphere of 100% steam for 5 hours. Then the resulting product was added to 20 liters of water purified from cations, mixed evenly with stirring, 1000 g of (NH ₄ ) ₂ SO ₄ was added and the mixture was stirred, heated to a temperature of 90-95°C and kept for 1 hour. Then, after filtration and washing, the filter cake was dried at 120°C, and then subjected to a second hydrothermal treatment by firing at 650°C in a 100% steam atmosphere for 5 hours to obtain a hydrothermally superstabilized calcium and rare earth free Y-type molecular sieve, which was subjected to two stages of ion exchange and two stages of hydrothermal superstabilization, designated as DZ1, the physicochemical properties of which are shown in Table 1.

After aging DZ1 in an unprotected state at 800° C. under atmospheric pressure in a 100% steam atmosphere, the crystallinity of the DZ1 molecular sieve before and after aging was analyzed by XRD, and the relative crystallinity retention after aging was calculated. The results are presented in Table 2.

Comparative example 2

2000 g of molecular sieve of the NaY type (in terms of dry matter) were added to 20 l of water purified from cations, mixed evenly with stirring, 1000 g of (NH4)2S04 were added and the mixture was stirred, heated to a temperature of 90-95 ° C and kept for 1 hour. Then, after filtration and washing, the filter cake was dried at 120°C and then subjected to hydrothermal treatment by firing at 650°C in an atmosphere of 100% steam for 5 hours. Then the resulting product was added to 20 liters of water purified from cations, mixed evenly with stirring, 203 ml of a Ca(NO ₃ ) ₂ solution (with a concentration of 248 g/l in terms of CaO) was added, then 100 ml of a RE(NO ₃ ) solution was added ₃ (with a concentration of 319 g/l in terms of RE ₂ O ₃ ) and 900 g (NH ₄ ) ₂ SO ₄ and the mixture was stirred, heated to a temperature of 90-95°C and kept for 1 hour. Then, after filtration and washing, the filter cake was dried at 120°C, and then subjected to a second hydrothermal treatment by calcination at 650°C in a 100% steam atmosphere for 5 hours to obtain a hydrothermally superstabilized rare earth element-containing Y-type molecular sieve, which was subjected to two stages ion exchange and two stages of hydrothermal superstabilization, designated DZ2, the physicochemical properties of which are shown in Table 1.

After aging DZ2 in an unprotected state at 800° C. under atmospheric pressure in a 100% steam atmosphere, the crystallinity of the DZ2 molecular sieve before and after aging was analyzed by XRD, and the retention of relative crystallinity after aging was calculated. The results are presented in Table 2.

Comparative example 3

2000 g of molecular sieve of the NaY type (in terms of dry matter) were added to 20 l of water purified from cations and mixed evenly with stirring, 243 ml of Ca(NO ₃ ) ₂ solution (with a concentration of 248 g/l in terms of CaO) was added. then 325 ml of RE(NO ₃ ) ₃ solution (319 g/l) was added and the mixture was stirred, heated to a temperature of 90-95°C and kept for 1 hour. The mixture was then filtered, washed and dried to obtain a water content of less than 1 wt. %. The resulting product was then subjected to gas-phase superstabilization by introducing heat-evaporated SiCl ₄ gas at a weight ratio of SiCl ₄ : Y-type molecular sieve of 0.4:1 and reacted at 580° C. for 1.5 hours. The resulting product was washed with 20 L of decationized water and filtered to obtain a gas-phase ultra-stabilized high silica Y type molecular sieve designated DZ3, the physicochemical properties of which are shown in Table 1.

After aging DZ3 in an unprotected state at 800° C. under atmospheric pressure in a 100% steam atmosphere, the crystallinity of the DZ3 molecular sieve before and after aging was analyzed by XRD, and the retention of relative crystallinity after aging was calculated. The results are presented in Table 2.

From Table 1, it can be seen that the modified Y type molecular sieve of the present application has the following advantages: low sodium content in terms of sodium oxide, relatively higher silica-alumina ratio and relatively lower non-lattice aluminum content, relatively higher secondary volume ratio pores with a pore size of 2.0-100 nm to total pore volume, relatively higher acid B/acid L ratio (the ratio of total acid B to total acid L), relatively higher crystallinity, defined when the molecular sieve has relatively more small lattice constant and certain content of calcium and rare earth element, and higher thermal stability.

From Table 2, it can be seen that the modified Y type molecular sieve of the present application shows relatively high retention of relative crystallinity after aging in an unprotected state at a severe condition of 800° C. for 17 hours, indicating that the modified Y type molecular sieve of the present application has high hydrothermal stability .

Examples 4-8

Examples 4-8 show the catalytic cracking activity and stability of catalysts containing the modified Y type molecular sieve of the present application.

The catalysts designated as SC1, SC2, SC3, SC4 and SC5 were prepared from the modified Y-type molecular sieves SZ1, SZ2 and SZ3 obtained in Examples 1-3. The catalysts were evaluated for microactivity on light oils after aging at 800°C in a 100% steam atmosphere for 4 or 17 hours and the results are shown in Table 3.

The method for preparing the catalysts is described below herein.

Catalyst SC1

714.5 g of aluminum oxide sol with an aluminum oxide content of 21 wt. % was added to 1565.5 g of cation-free water, stirring began, and 2763 g of kaolin with a solids content of 76 wt. % was added and dispersed for 60 minutes. 2049 g pseudoboehmite with aluminum oxide content 61 wt. % was added to 8146 g of cation-free water, 210 ml of hydrochloric acid with a mass concentration of 36% was added with stirring and a suspension of dispersed kaolin was added after 60 minutes of acidification. Then, 1500 g (on a dry basis) of ground molecular sieve SZ1 was added, mixed uniformly with stirring, then spray dried, washed and dried to obtain a catalyst designated as SC1. The resulting catalyst SC1 contained, in terms of dry matter, 30 wt. % modified molecular sieve type Y, 42 wt. % kaolin, 25 wt. % pseudoboehmite and 3 wt. % aluminum oxide sol.

Catalysts SC2 and SC3

Catalysts SC2 and SC3 were prepared in the same manner as described above for catalyst SC1, using molecular sieves SZ2 and SZ3, respectively, instead of molecular sieve SZ1. The resulting catalysts SC2 and SC3 contain, in terms of dry matter, 30 wt. % modified molecular sieve type Y, 42 wt. % kaolin, 25 wt. % pseudoboehmite and 3 wt. % aluminum oxide sol.

Catalysts SC4 and SC5

Catalysts SC4 and SC5 were prepared in substantially the same manner as described above for catalyst SC1 using molecular sieve SZ2, the amount of each starting material being adjusted accordingly so that the resulting catalyst SC4 contained, on a dry matter basis, 25 wt. % molecular sieve SZ2, 47 wt. % kaolin, 24 wt. % pseudoboehmite and 4 wt. % aluminum oxide sol; and the resulting catalyst SC5 contains 40 wt. % molecular sieve SZ2, 30 wt. % kaolin, 20 wt. % pseudoboehmite and 10 wt. % aluminum oxide sol.

Microactivity assessment for light oil

The light oil microactivity of each catalyst was assessed according to the standard RIPP 92-90 method (see "Petrochemical Analysis Methods (RIPP Test Methods)", edited by Cuiding YANG et al., Science Press, September 1990, First Edition, pp. 263-268 ) in which the catalyst loading was 5.0 g, the reaction temperature was 460°C, and the feed oil was Dagang light diesel fuel with a boiling range of 235-337°C. The product composition was analyzed by gas chromatography and microactivity for light oil was calculated based on the product composition.

Microactivity for light oil (MA) = (gasoline production below 216°C + gas production + coke production) / total amount of raw materials × 100%.

Comparative examples 4-6

Comparative Examples 4-6 show the catalytic cracking activity and stability of catalysts containing the ultra-stable Y-type molecular sieves prepared in Comparative Examples 1-3.

Catalysts DC1, DC2 and DC3 were prepared according to the catalyst preparation method described in Examples 4 to 8 using the Y-type ultrastable molecular sieves DZ1, DZ2 and DZ3 obtained in Comparative Examples 1 to 3, respectively. All of the obtained catalysts DC1, DC2 and DC3 contain, in terms of dry matter, 30 wt. % ultrastable molecular sieve type Y, 42 wt. % kaolin, 25 wt. % pseudoboehmite and 3 wt. % aluminum oxide sol. Each catalyst was evaluated for light oil microactivity after aging at 800° C. in an atmosphere of 100% steam for 4 or 17 hours according to the evaluation method described in Examples 4-8, and the results are shown in Table 3.

Examples 9-13

Examples 9-13 show the performance characteristics for catalytic cracking of catalysts containing a modified Y-type molecular sieve according to the present application.

Catalysts SC1, SC2, SC3, SC4 and SC5 were aged at 800° C. under atmospheric pressure in a 100% steam atmosphere and their performance for catalytic cracking was evaluated in a small fixed fluidized bed reactor (ACE). The cracking gas and product oils were collected separately and analyzed by gas chromatography. The catalyst loading was 9 g, the reaction temperature was 500°C, the average hourly feed rate was 16 h ^-1 , and the mass ratio of catalyst to oil was shown in Table 5. The properties of the feed oil used in the ACE test are shown in Table B4. and the results are shown in Table 5.

Branched hydrocarbon content in gasoline (wt.%) = isoparaffin content in gasoline (wt.%) + branched alkene content in gasoline (wt.%)

Branched C4 hydrocarbon content (wt%) = isobutane content (wt%) + isobutene content (wt%).

Comparative Examples 7-9

Comparative Examples 7-9 show the catalytic cracking performance of catalysts containing the ultrastable Y-type molecular sieves obtained in Comparative Examples 1-3.

Catalysts DC1, DC2 and DC3 were aged at 800°C under atmospheric pressure in an atmosphere of 100% steam, and their performance for catalytic cracking was evaluated in a small fixed fluidized bed reactor (ACE) according to the method described in Examples 9-13. The properties of the crude oil used in the ACE test are shown in Table B4 and the results are shown in Table 5.

From the results shown in Tables 3 and 5, it can be seen that the catalytic cracking catalyst obtained by using the molecular sieve of the present application as an active component has very high hydrothermal stability, and when used in heavy oil catalytic cracking, shows higher heavy conversion activity. oil, significantly lower selectivity to coke, significantly increased yield of total liquid, light oil and gasoline, and significantly increased yield of branched C4 hydrocarbons, and the branched hydrocarbon content of gasoline is also significantly increased.

In the description above, the idea of the present application has been described with reference to embodiments. However, those skilled in the art will appreciate that various modifications and changes may be made without departing from the scope of the present invention as defined in the appended claims. Accordingly, the description and figures are to be considered as illustrative and not limiting, and all such modifications and changes are intended to be embraced by the present invention.

It should be understood that some of the features described individually in multiple embodiments for the sake of clarity may also be provided in combination in a single embodiment. In contrast, many different features that are described in one embodiment for brevity may also be provided individually or in any subcombination in different embodiments.

Claims (26)

1. A modified Y-type molecular sieve for catalytic cracking of hydrocarbon oils, having a calcium content of 0.3-4 wt.% in terms of calcium oxide, a rare earth content of 2-7 wt.% in terms of rare earth oxide and a sodium content of not more than than 0.5 wt.% in terms of sodium oxide, in terms of dry matter and based on the weight of the specified modified molecular sieve type Y; wherein the modified Y-type molecular sieve has a total pore volume of 0.33-0.39 ml/g, the ratio of the volume of secondary pores with a pore size of 2-100 nm to the total pore volume of 10-25%, the lattice constant of 2.440-2.455 nm, the ratio the content of non-lattice aluminum to the total aluminum content is not more than 20%, the lattice destruction temperature is not lower than 1050°C and the ratio of Brønsted acid to Lewis acid in the total acid content is not less than 2.30, as determined using infrared spectroscopy of adsorbed pyridine at 200°C. 2. The modified Y-type molecular sieve according to claim 1, wherein the modified Y-type molecular sieve has a pore volume ratio of secondary pores with a pore size of 2-100 nm to the total pore volume of 15-21%, preferably 17-21%; and/or the modified Y-type molecular sieve has a non-lattice aluminum to total aluminum content ratio of 13-19% and a silica-alumina lattice ratio calculated as a SiO ₂ /Al ₂ O ₃ molar ratio of 7.3-14. 3. The modified Y-type molecular sieve according to any one of the preceding paragraphs, wherein the modified Y-type molecular sieve has a lattice breakdown temperature of 1050-1080°C or 1050-1063°C; and/or preferably the modified Y-type molecular sieve has a Brønsted acid to Lewis acid ratio of total acid content of 2.3-5.0, 2.4-4.2, or 2.4-3.5, as determined by pyridine absorption infrared spectroscopy at 200°C. 4. The modified Y-type molecular sieve according to any one of the preceding claims, wherein the modified Y-type molecular sieve has a relative crystallinity retention of 35% or more, such as 36-45% or 35-48%, after aging at 800°C under an atmospheric pressure of 100 % steam atmosphere for 17 hours; and/or preferably the modified Y-type molecular sieve has a relative crystallinity of 58-68%. 5. A modified molecular sieve of type Y according to any of the preceding paragraphs, wherein the modified molecular sieve of type Y has a calcium content of 0.5-3.5 wt.% in terms of calcium oxide, a rare earth element content of 2.5-6.5 wt. % in terms of rare earth oxide, sodium content 0.2-0.5 wt.% in terms of sodium oxide, lattice constant 2.442-2.452 nm and silica-alumina lattice ratio 8-12.6, calculated as the molar ratio of SiO ₂ /Al ₂ O ₃ . 6. The modified Y-type molecular sieve according to any one of the preceding claims, wherein the modified Y-type molecular sieve has an O1s electron binding energy of not more than 532.70 eV, for example, 532.55-532.65 eV. 7. A method for producing a modified molecular sieve of type Y according to claim 1, comprising the steps: (1) contacting the NaY type molecular sieve with a solution of a soluble calcium salt and a soluble rare earth salt for an ion exchange reaction to produce a Y type molecular sieve containing calcium and a rare earth element having a reduced sodium content; (2) subjecting the Y-type molecular sieve obtained in step (1) to calcination at a temperature of 350-480°C in an atmosphere of 30-90 vol. % steam for 4.5-7 hours and optionally drying to obtain a Y-type molecular sieve with a reduced lattice constant; And (3) contacting the reduced lattice constant type Y molecular sieve with gaseous silicon tetrachloride to react at a weight ratio of SiCl ₄ to reduced lattice constant type Y molecular sieve on a dry matter basis of 0.1:1 to 0.7: 1 and a reaction temperature of 200-650°C for a reaction time of 10 minutes to 5 hours to obtain a modified Y-type molecular sieve. 8. The method according to claim 7, in which the Y-type molecular sieve obtained in step (1) has a lattice constant of 2.465-2.472 nm, a sodium content of not more than 8.8 wt.% in terms of sodium oxide; preferably, the Y-type molecular sieve obtained in step (1) has a calcium content of 0.3-10 wt.%, for example 0.9-9 wt.%, in terms of calcium oxide, a rare earth element content of 2-8 wt. %, for example 2.1-7 wt.%, in terms of rare earth oxide, sodium content 4-8.8 wt.%, for example, 5.0-8.5 wt.%, in terms of sodium oxide and lattice constant 2.465-2.472 nm. 9. The method according to claim 7 or 8, wherein in step (1), NaY molecular sieve, soluble calcium salt, soluble rare earth salt and water are mixed in a mass ratio of NaY molecular sieve: soluble calcium salt: soluble rare earth salt: H ₂ O 1:0.009-0.28:0.005-0.09:5-15 for ion exchange. 10. Method according to any one of paragraphs. 7-9, in which step (1) further involves mixing the NaY type molecular sieve with water and adding soluble calcium salt and/or soluble calcium salt solution and soluble rare earth salt solution and/or soluble rare earth salt solution thereto while stirring to carry out ion exchange reactions; conditions for the ion exchange reaction include: exchange temperature 15-95°C and exchange time 30-120 minutes; preferably the soluble calcium salt solution and the soluble rare earth salt solution are aqueous solutions of the soluble calcium salt and the soluble rare earth salt, and/or preferably, the soluble calcium salt is calcium chloride and/or calcium nitrate, and the soluble rare earth salt is a rare earth chloride and/or a rare earth nitrate. 11. Method according to any one of paragraphs. 7-10, in which in step (2), the firing temperature is 380-460°C, the firing atmosphere is an atmosphere of 40-80% steam, and the firing time is 5-6 hours; preferably, the Y-type molecular sieve with reduced lattice constant obtained in step (2) has a lattice constant of 2.450-2.462 nm and a water content of not more than 1 wt%. 12. Method according to any one of paragraphs. 7-11, wherein step (3) further comprises washing the resulting modified Y-type molecular sieve with water under conditions including: molecular sieve:H ₂ O ratio 1:5-20, pH 2.5-5.0 and washing temperature 30 -60°C. 13. Modified molecular sieve type Y, obtained by the method according to any one of paragraphs. 7-12. 14. A catalytic cracking catalyst containing 10-50 wt.% in terms of dry matter of a modified Y-type molecular sieve, 10-40 wt.% of an alumina-based binder in terms of alumina and 10-80 wt.% in terms of clay dry matter, based on the weight of the catalytic cracking catalyst; wherein the modified Y-type molecular sieve is a modified Y-type molecular sieve according to any one of claims. 1-6 and 13. 15. Use of a modified Y-type molecular sieve according to any one of paragraphs. 1-6 and 13 for the catalytic cracking of hydrocarbon oils, providing for contact of the hydrocarbon oil with a catalytic cracking catalyst containing a modified Y-type molecular sieve according to any one of paragraphs. 1-6 and 13.