CN103506153B - Catalytic cracking catalyst for reducing coke yield and producing gasoline - Google Patents

Abstract

A catalytic cracking catalyst for reducing the coke yield and producing gasoline, containing 10% to 50% by weight of modified Y-type molecular sieves on a dry basis, and no more than 30% by weight of specific rare earth-containing Y-type molecular sieves on a dry basis 10 wt%-70 wt% clay based on dry basis and 10 wt%-40 wt% inorganic oxide binder based on oxide; the modified Y-type molecular sieve has a unit cell constant of 2.420-2.440 nm, by weight percentage, P is 0.05-6%, RE ₂ O ₃ is 0.03-10%, alumina is less than 22%, and the specific hydroxyl nest concentration is less than 0.35mmol/g. The catalytic cracking catalyst provided by the invention can reduce coke formation, increase the utilization rate of heavy oil, and improve gasoline selectivity.

Description

A Catalyst for Catalytic Cracking to Reduce Coke Yield and Produce Gasoline

technical field

The invention relates to a catalytic cracking catalyst for hydrocarbon oil, and further relates to a catalytic cracking catalyst for reducing coke yield and improving gasoline selectivity.

Background technique

With the decreasing of petroleum resources, it has become an indisputable fact that petroleum raw materials become heavy and inferior. As the main processing method to convert heavy oil into gasoline and diesel light fuel oil, catalytic cracking inevitably needs to process more and lower quality heavy oil feedstock. The reduction of conversion rate and the increase of coke yield are one of the manifestations of the impact of the heavy and poor quality of feedstock oil on catalytic cracking. Aiming at this, people have done a lot of research on molecular sieve modification, catalyst manufacturing and process design (Liu Tao, Zhang Zhongdong, Zhang Haitao, etc. Sinoforeign Energy. 2009, 14(1): 71-77). However, most of the current catalyst designs and industrial plant operations achieve high yields of light oil and liquefied gas products by increasing the conversion rate of cracking reactions, resulting in significantly higher coke yields and a waste of raw oil resources. To improve the utilization rate of heavy oil, the conversion rate can be properly controlled to reduce the coke yield to improve the coke selectivity. In the composition of FCC catalysts, molecular sieves have a decisive influence on the comprehensive reaction performance of catalysts, so modifying molecular sieves is one of the most effective means to improve the reaction performance of catalytic cracking catalysts.

Coke is composed of various hydrogen-poor compounds with different degrees of hydrogen deficiency, and is the product of hydrogen transfer reaction. Therefore, to reduce the yield of coke, it is necessary to appropriately reduce hydrogen transfer reaction. The main process of hydrogen transfer reaction is the adsorption, reaction and desorption of protonated olefins on the acidic center of molecular sieves. Molecular sieves have a high density of acid centers and increased hydrogen transfer reactions. The acid density of molecular sieve is related to its skeleton silicon aluminum ratio. Molecular sieves with low skeleton silicon-aluminum ratio have more acid centers of aluminum-oxygen tetrahedron, high acid density of molecular sieves, more hydrogen transfer reactions, fast speed, and high coke yield; while molecular sieves with high skeleton silicon-aluminum ratio have low acid center density, The hydrogen transfer reaction is relatively less, and the coke yield is reduced. It can be seen that to ensure good coke selectivity of the active component, the active component must have a low unit cell constant and an appropriate acid density.

As we all know, during the operation of the cracking unit, in order to maintain the stability of the reaction activity, it is necessary to continuously discharge the old catalyst and replenish the fresh catalyst. Therefore, there is an age distribution of the catalyst. Catalysts of different ages have different reactivity. In the fresh catalyst, the molecular sieve unit cell is larger, the cracking activity is high, the hydrogen transfer ability is strong, and the coke yield is high; while the long-term operation catalyst has a skeleton dealumination of the molecular sieve under hydrothermal conditions, and the structure collapses, which reduces the cracking activity of the catalyst and the reaction selection. Sexual deterioration. Obviously, the catalysts in these two states are not conducive to the improvement of the utilization rate of heavy oil. To improve the utilization rate of catalyst heavy oil, it is necessary to start with improving the reactivity of molecular sieves under different deactivation degrees. On the one hand, molecular sieves with low unit cell sizes are used to reduce the coke selectivity of fresh molecular sieves. On the other hand, through modification, Improve the activity stability of the molecular sieve to increase the equilibrium activity, and minimize the activity difference of the molecular sieve at different stages of hydrothermal aging, so as to reduce the coke selectivity of the catalyst as a whole, thereby improving the utilization rate of heavy oil.

The use of Y-type molecular sieve with low unit cell size will inevitably reduce the catalyst activity and heavy oil conversion ability, so other modifying elements must be added to improve the performance of active components. Rare earth modification can significantly improve the cracking activity and hydrothermal stability of molecular sieves, but a large number of studies have shown that molecular sieve coke with high rare earth content has poor selectivity, and medium and low rare earth content is more suitable. In recent years, people have used the modification method of introducing phosphorus and rare earth into molecular sieves to further improve the catalytic performance.

CN1624079A discloses a hydrocarbon cracking catalyst containing modified faujasite, wherein the modification method of zeolite is firstly to carry out exchange reaction of faujasite with phosphorus compound and ammonium compound, the weight ratio of water to zeolite is 2-25, pH2. 0~6.5, temperature 10~150℃, exchange time 0.1~4 hours, then introduce rare earth solution into the exchange slurry, reaction time 1~60 minutes, further react, filter, wash, and modify with phosphorus and rare earth Zeolite is obtained by calcining at 250-800°C and 1-100% water vapor for 0.1-3.5 hours. The unit cell constant of the modified zeolite prepared by this modification method is 2.440-2.465nm, the sodium oxide is 2.0-6.5% by weight, the phosphorus content is 0.01-3% by weight, and the rare earth oxide is 0.1-15% by weight. The catalyst containing the molecular sieve has good activity stability, high gasoline yield, low coke yield, strong heavy oil cracking ability and heavy metal pollution resistance. The catalyst prepared by using the modified molecular sieve has high gasoline yield and good coke selectivity. However, the unit cell constant of the molecular sieve obtained by this preparation method is relatively large, which will affect the coke selectivity of the molecular sieve catalyst.

CN 1506161A discloses a rare earth ultra-stable Y molecular sieve active component. This modified molecular sieve contains 8-25% by weight of rare earth oxide, 0.1-3.0% by weight of phosphorus, 0.3-2.5% by weight of sodium oxide, and 30-55% of crystallinity , The unit cell constant is 2.455-2.472 nanometers. Molecular sieve preparation uses NaY zeolite as raw material, after rare earth exchange and first roasting, to obtain "cross-baked" rare earth NaY; then react with rare earth, phosphorus-containing substances and ammonium salt, and perform second roasting treatment to obtain phosphorus and Rare earth modified modified Y zeolite. The coke yield of this modified molecular sieve is moderate. The molecular sieve prepared by this method has a high rare earth content and a large unit cell constant, which affects the selectivity of the molecular sieve coke.

CN1317547A discloses a FCC catalyst, which contains a phosphorus and rare earth composite modified Y zeolite, the molecular sieve is mixed and exchanged by NaY zeolite with rare earth and ammonium salt and then hydrothermally roasted, reacted with phosphorus compound, and then carried out the second Prepared by secondary roasting treatment, wherein the weight ratio of RE ₂ O ₃ /Y zeolite is 0.02-0.18, the weight ratio of ammonium salt/Y zeolite is 0.1-1.0, the weight ratio of P/Y zeolite is 0.003-0.05, and the roasting temperature is 250～ 750°C, water vapor condition 5-100%, time 0.2-3.5 hours.

CN 101537366A reports a modified molecular sieve that can improve coking performance, which is characterized in that the molecular sieve is obtained by the preparation method of NaY molecular sieve through double-crossing and double-baking. In terms of weight percentage, RE ₂ O ₃ is 0.05-4.0%, and P is 0.05-5.0%, the unit cell is 2.430-2.440nm, and the crystallinity is 35-55%. The molecular sieve has a larger medium and large pore volume and good stability. While reducing the coke yield of the catalyst, the heavy oil cracking ability is further improved, thereby increasing the total liquid yield, which is especially beneficial to the increase in the yield of light oil.

EP 0421422 mentions a faujasite for hydrocracking catalyst, characterized in that the faujasite has an infrared absorption of at least 20% at a wavenumber of 3740±10cm ^-1 and at least 5% at a wavenumber of 3560±10cm ^-1 Infrared absorption, the former is at least 2 more than the latter. The specific surface area of the faujasite is at least 650m ² /g, the silicon-aluminum ratio of the framework is 20-50, and the unit cell constant is 24.15-23.50.

CN 1951814A discloses a modified Y zeolite, which is characterized in that the modified Y zeolite has a silicon-aluminum ratio of 7-30, a specific surface area of 700-900m ² /g, a unit cell constant of 2.425-2.445nm, and a relative crystallinity ≥ 80 %, Na ₂ O content ≤0.25%, secondary pores of 1.7-10nm account for more than 45% of the total pore volume, non-skeletal aluminum accounts for more than 30% of the total aluminum content, and infrared acidity is 0.15-0.55mmol/g. The modified zeolite is prepared by using NaY as a raw material through ammonium exchange, hydrothermal treatment, removal of non-framework aluminum, pore expansion, and secondary hydrothermal treatment. The modified zeolite can be used as the acidic component of various catalysts, such as medium oil hydrocracking catalyst.

The above several patent documents use hydrothermal dealumination and/or chemical dealumination to increase the silicon-aluminum ratio of Y-type molecular sieves _. /Al ₂ O ₃ molar ratio ≥ 15) process will often lead to the destruction of zeolite structure, so that the crystallinity of zeolite will decrease.

US 5013699 proposes a treatment method for Y zeolite, which is to exchange NaY zeolite with ammonium ion, then conduct high-temperature steam treatment, and then perform ammonium exchange and remove aluminum under the condition of pH<4 to obtain zeolite product. In this treatment method, the zeolite sample is treated under the condition of low pH value, and no protection measures are adopted, which will easily lead to the destruction of the zeolite framework and reduce the crystallinity of the zeolite.

US 4503023 discloses a kind of LZ～210 zeolite and its preparation method. NaY zeolite is dealuminated with fluorosilicate to increase the silicon-aluminum ratio of the zeolite. When dealuminating Y zeolite, the molar ratio of SiO ₂ /Al ₂ O ₃ of the zeolite product should generally not be higher than 13, otherwise, the crystallinity of the zeolite product will be greatly reduced. In addition, the modified Y zeolite prepared by the method of dealuminating and supplementing silicon with fluorosilicate has very few secondary pores, which is unfavorable for heavy oil catalytic cracking reaction.

Contents of the invention

The purpose of the present invention is to provide a kind of catalytic cracking catalyst of prolific gasoline, which contains a kind of "three-intersected-three-baked" phosphorus and Y-type molecular sieve modified by rare earth, which can improve gasoline selectivity and reduce coke yield.

The invention provides a catalytic cracking catalyst for reducing coke yield and producing diesel oil, which contains 10% to 50% by weight of modified Y-type molecular sieve on a dry basis, and no more than 30% by weight of a specific rare earth-containing compound on a dry basis. Y-type molecular sieve, 10% to 70% by weight of clay based on dry basis and 10% to 40% by weight of inorganic oxide binder based on oxide; the modified Y-type molecular sieve has a unit cell constant of 2.420 ～2.440nm, by weight percentage, P is 0.05%～6%, RE ₂ O ₃ is 0.03%～10%, alumina is less than 22%, specific hydroxyl nest concentration is less than 0.35mmol/g, the said

In the formula, M _200°C , M _500°C and M _800°C respectively represent the percentage of weight loss measured by the sample at a temperature of 200°C, 500°C and 800°C, and C is the crystallinity of the sample;

The specific rare earth-containing Y-type molecular sieve is a rare earth-modified gas-phase ultrastable Y-type molecular sieve and/or a rare-earth-containing acid-treated hydrothermal dealuminated Y-type molecular sieve.

The preparation method of the catalytic cracking catalyst, the method comprises preparing the modified Y-type molecular sieve, the prepared modified Y-type molecular sieve, the specific Y-type molecular sieve containing rare earth, clay and inorganic oxide The steps of mixing and beating the binder and spray drying;

The modified Y-type molecular sieve (also known as a modified Y-type molecular sieve containing phosphorus and rare earth) can be (obtained by the preparation method of three-cross three-baking, the so-called "three-cross three-baking" is a kind of The general abbreviation of molecular sieve modification process refers to the combined modification process using NaY molecular sieve as raw material, three times of exchange and three times of hydrothermal treatment. The rare earth and phosphorus are exchanged by adding phosphorus-containing exchange solution and rare earth-containing exchange solution. Phosphorus can be It can be added in any exchange process, which can be added once or several times. The rare earth can be added in any exchange process other than the first exchange process. The exchange process can also add a dealumination agent to promote the removal of aluminum. It is carried out in any exchange process other than the exchange. Filtration and washing after exchange are conventional methods.

The catalytic cracking catalyst of the present invention can exhibit good stability in the catalytic cracking process, can be used for heavy oil catalytic cracking, can reduce coke formation, improve gasoline selectivity, and improve heavy oil utilization rate.

Description of drawings

The comparison curve of the crystallinity data of Fig. 1 embodiment and comparative example.

The comparison curve of crystal retention data of Fig. 2 embodiment and comparative example.

The activity data comparison curve of Fig. 3 embodiment and comparative example.

The coke selectivity data comparison curve of Fig. 4 embodiment and comparative example.

Detailed ways

The modified Y-type molecular sieve of the present invention is a modified Y-type molecular sieve containing phosphorus and rare earths, which is obtained from NaY molecular sieve through the preparation method of "three-crossing and three-baking", and its cell constant is 2.420-2.440nm, preferably unit The constant is 2.428-2.438nm, by weight percentage, P is 0.05-6%, preferably 0.1-4.5%, RE ₂ O ₃ is 0.03-10%, preferably 0.1-4.5%, alumina is less than 22%, usually 10-22%, preferably less than 20%, the specific hydroxyl nest concentration is less than 0.35mmol/g, such as 0.01mmol/~0.35mmol/g, preferably less than 0.3mmol/g, the described

In the formula, M _200°C , M _500°C and M _800°C represent the percentage of weight loss measured at the temperature of 200°C, 500°C and 800°C, respectively, and C is the crystallinity of the sample.

The dealumination of the zeolite molecular sieve framework forms a "hydroxy nest" composed of four adjacent Si-OH in its aluminum vacancy, which is the defect site in the zeolite molecular sieve lattice, and its number is directly related to the stability of the zeolite structure. The more the number of "hydroxyl nests", the more aluminum vacancies formed on the molecular sieve due to the dealumination of the framework, and the poorer the structural stability of the molecular sieve. The aluminum vacancies formed by Y-type molecular sieves in the process of hydrothermal or chemical dealumination are filled with free silicon. The dealumination method and treatment conditions in the modification process of molecular sieves directly affect the stability of modified molecular sieves. The inventors conducted a large number of experiments. On the basis of the modified Y-type molecular sieve after "three-crossing and three-baking", the aluminum vacancies formed by the dealumination of the framework can be fully filled with silicon, and the number of hydroxyl nests is reduced, so the stability is greatly improved.

In the modified Y molecular sieve of the present invention, the specific hydroxyl nest concentration is characterized by the method provided by the literature (Liu Xingyun, Liu Hui, Li Xuanwen, etc. Acta Physicochemical Sinica. 1998, 14(12): 1094-1097). The characterization method is calculated by performing thermogravimetric analysis on the sample.

On the weight loss curve, below 200°C corresponds to the weight loss of desorbed water, 200°C to 500°C corresponds to the weight loss of zeolite deammonization and hydroxyl nest dehydration, and 500°C to 800°C corresponds to the weight loss of dehydroxylation. The NH4 ⁺ decomposition on the Y-type molecular sieve will produce acidic hydroxyl groups, so the number of moles of hydroxyl groups corresponds to NH3. In this way, after calculating the number of moles of hydroxyl groups from the weight loss curve at 500°C to 800°C, convert it into the mass of _NH3 , and then subtract the amount of NH3 from the weight loss calculated from the weight loss curve at 200°C to 500°C to calculate the number of moles of hydroxyl nests .

In the calculation of the concentration of hydroxyl nests, one hydroxyl nest disappears due to the removal of two molecules of water, so its molar weight is 36, and two hydroxyl nests lose one molecule of water, so its molar weight is 9.

The preparation method of the above-mentioned modified Y-type molecular sieve is obtained by using NaY molecular sieve as a raw material through the preparation process of "three-cross three-baking". The so-called "three-cross three-baking" is a general abbreviation for a molecular sieve modification process in the field. That is, the combined modification process of three times of exchange and three times of hydrothermal treatment is adopted. The rare earth and phosphorus are exchanged, and the exchange solution containing phosphorus and the exchange solution containing rare earth are added for exchange. Phosphorus can be added in any exchange process, and can be added once or several times. The rare earth can be added in any exchange process other than the first exchange, and the exchange process can also add a dealumination agent to carry out chemical dealumination to promote the removal of aluminum. The chemical dealumination process can be carried out in any exchange process other than the first exchange.

The phosphorus-containing substance in the phosphorus-containing exchange solution of the present invention is selected from one or more of orthophosphoric acid, phosphorous acid, pyrophosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, and aluminum phosphate.

The ammonium-containing substance in the ammonium solution is selected from one or more of ammonium chloride, ammonium nitrate, ammonium carbonate, ammonium bicarbonate, ammonium oxalate, ammonium sulfate, and ammonium bisulfate.

The rare earth-containing substance in the rare earth-containing exchange liquid is selected from one or more of lanthanum oxide, cerium oxide, lanthanum nitrate, cerium nitrate, lanthanum chloride, cerium chloride, mixed rare earth nitric acid, and mixed rare earth chloride.

The inorganic acid for adjusting the pH value of the exchange liquid is selected from one or more of hydrochloric acid, sulfuric acid, and nitric acid.

The dealuminizing agent is selected from organic acids (including ethylenediaminetetraacetic acid, oxalic acid, citric acid, sulfosalicylic acid), inorganic acids (including fluorosilicic acid, hydrochloric acid, sulfuric acid, nitric acid), organic and inorganic Salts (including ammonium oxalate, ammonium fluoride, ammonium fluorosilicate, ammonium fluoroborate).

A kind of preparation process of preferred modified Y type molecular sieve can comprise the following steps:

1) NaY zeolite, ammonium salt, ammonium phosphate salt and water are mixed according to the weight ratio of NaY molecular sieve: ammonium salt: ammonium phosphate salt: water = 1: 0.4～1.0: 0～0.04: 5～10 to obtain a slurry, which is adjusted with inorganic acid The pH value of the slurry is 3.0 to 4.5, and then treated at 70°C to 95°C for at least 0.5h, and usually washed after 0.5 to 10 hours, wherein the NaY molecular sieve is calculated on a dry basis, and the ammonium phosphate is calculated on an elemental phosphorus basis; Ammonium phosphate is a phosphorus-containing ammonium salt, such as one or more of ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium pyrophosphate, and ammonium phosphite;

2) Calcining the product obtained in step 1) at a temperature of 350°C to 650°C in an atmosphere of 1% to 100% water vapor for at least 0.5 hours, usually 0.5 to 10 hours, preferably 2 to 6 hours to obtain a baked molecular sieve;

3) Mix the one-baking molecular sieve obtained in step 2) with phosphoric acid and dealumination agent according to the weight ratio of one-baking molecular sieve: phosphoric acid: dealumination agent: water = 1:0～0.04:0.02～0.3:5～10, and use inorganic Adjust the pH value to 2.4-3.5 with acid, and then treat at 50°C-90°C for at least 0.5 hours, usually 0.5-10 hours, filter and wash, the washing water temperature is ≥50°C, usually 50-95°C, wherein, a baked molecular sieve On a dry basis, phosphoric acid is calculated as elemental phosphorus.

4) Calcining the product obtained in step 3) at a temperature of 350° C. to 650° C. in an atmosphere of 1% to 100% water vapor for at least 0.5 hours, usually 0.5 to 10 hours, preferably 2 to 6 hours, to obtain a second-baked molecular sieve;

5) Mix the two-baked molecular sieve obtained in step 4) with rare earth chloride and water according to the weight ratio of two-baked molecular sieve: rare earth chloride: water = 1: 0.01-0.05: 5-10, and then mix them at 70°C-90°C Treat for at least 0.5 hours, usually 0.5~10 hours, filter; wash, the washing water temperature is ≥50°C, usually 50~95°C, wherein, the dibaked molecular sieve is calculated on a dry basis, and the rare earth chloride is calculated as RE ₂ O ₃ ;

6) Calcining the product obtained in step 5) at 350° C. to 650° C. in an atmosphere of 1% to 100% water vapor for at least 0.5 hours, usually 0.5 to 10 hours, preferably 2 to 6 hours to obtain a modified Y-type molecular sieve.

According to the catalyst of the present invention, the content of the specific rare earth-containing Y-type molecular sieve is no more than 30% by weight, preferably 2-28% by weight.

According to the catalyst of the present invention, wherein the specific rare earth-containing Y-type molecular sieve is the second Y-type molecular sieve and/or the third Y-type molecular sieve, wherein:

The second Y-type molecular sieve is a gas-phase ultra-stable Y-type molecular sieve containing rare earths, and its preparation method includes: contacting the Y-type molecular sieves containing rare earths with silicon tetrachloride under stirring, and the contact temperature is 100-500 ° C, The contact time is 0.1-10 hours, and the weight ratio of the rare earth-containing Y-type molecular sieve to silicon tetrachloride is 1:0.05-0.5. The specific preparation method of the second Y-type molecular sieve can refer to the patent CN1286721C, especially the examples 5, 6 and 8 therein; preferably, the content of the second Y-type molecular sieve does not exceed 15% by weight.

The third Y-type molecular sieve is a rare earth-containing acid-treated hydrothermal ultra-stable Y-type molecular sieve, and its preparation method includes: mixing the ultra-stable Y-type molecular sieve and an acid solution with a concentration of 0.01-2N at a liquid-solid ratio (weight) The ratio of 4-20 is fully mixed at 20-100 ° C, treated for 10-300 minutes, washed, filtered, and then added with a rare earth salt solution for rare earth ion exchange, followed by washing, filtering and drying after the exchange. The specific preparation method of the third Y-type molecular sieve can refer to the patent CN100497175C, especially the examples 1-6 therein.

Preferably, the specific rare earth-containing Y-type molecular sieve is the third Y-type molecular sieve, and its content is preferably 10-30% by weight.

The catalyst prepared by the present invention can also contain other molecular sieves except the modified Y-type molecular sieve and the specific rare-earth-containing Y-type molecular sieve, and other Y-type molecular sieves commonly used in catalytic cracking catalysts are selected from other molecular sieves. One or more of molecular sieves, molecular sieves with MFI structure, Beta molecular sieves, and non-zeolite molecular sieves. The other Y-type molecular sieves such as one or more of REY molecular sieves, USY molecular sieves, HY molecular sieves, DASY molecular sieves, and REHY molecular sieves; the above-mentioned molecular sieves with MFI structure are such as one of ZSM-5, ZRP, and ZSP molecular sieves One or several kinds; the non-zeolite molecular sieve is one or several kinds of SAPO and titanium-silicon molecular sieves. The content of said other molecular sieves is preferably not more than 10% by weight.

The catalytic cracking catalyst provided by the present invention contains 10%-50% by weight of the modified Y-type molecular sieve on a dry basis, no more than 30% by weight on a dry basis of a specific rare earth-containing Y-type molecular sieve, and a dry basis 10%-70% by weight of clay and 10%-40% by weight of inorganic oxide binder in terms of oxides. The content of the specific rare earth-containing Y-type molecular sieve is preferably 0.5-30% by weight, more preferably 2-25% by weight. Preferably, the catalytic cracking catalyst contains 15-35% by weight of the modified Y-type molecular sieve and 2-10% by weight of DASY molecular sieve on a dry basis.

According to the catalyst of the present invention, wherein the clay is selected from one or more clays used as cracking catalyst components, such as kaolin, halloysite, montmorillonite, diatomaceous earth, halloysite, One or more of saponite, retortite, sepiolite, attapulgite, hydrotalcite, and bentonite. These clays are well known to those of ordinary skill in the art.

The binder of the present invention is one or more of the commonly used inorganic oxide binders for catalytic cracking catalysts, preferably alumina binders, and the alumina binders are selected from commonly used cracking catalysts. One or more of various forms of alumina, hydrated alumina and aluminum sol. For example, selected from γ-alumina, η-alumina, θ-alumina, χ-alumina, Pseudoboemite, Boehmite, Gibbsite or Bayer One or several kinds of Bayerite, preferably double aluminum binder of pseudoboehmite and aluminum sol.

The catalyst of the present invention can be prepared according to any existing cracking catalyst preparation method, such as mixing and beating clay, molecular sieves, and alumina binders, spray drying, washing, filtering, and drying steps. These methods are described in patents CN1098130A, CN1362472A , CN1727442A, CN1132898C, and CN1727445A have detailed descriptions, which are hereby incorporated by reference.

Spray drying, washing and drying are prior art, and the present invention has no special requirements.

The following examples will further illustrate the present invention, but do not limit the content of the present invention thereby.

In embodiment and comparative example, used raw material specification is as follows:

NaY molecular sieve, industrial product, silicon-aluminum ratio > 4.7, crystallinity > 85%

Mixed rare earth chloride, technical grade

Ammonium sulfate, chemically pure

Phosphoric acid, chemically pure

Ammonium dihydrogen phosphate, chemically pure

Sulfuric acid, chemically pure

Oxalic acid, solid, chemically pure

Fluorosilicate, technical grade

Hydrochloric acid, chemically pure

The second rare earth-containing Y-type molecular sieve (Z2) was prepared according to the method of Example 5 in the patent CN1286721C;

The third rare earth-containing Y-type molecular sieve (Z3) was prepared according to the method in Example 1 of patent CN100497175C;

DASY-2.0 molecular sieve is a commercial product of Sinopec Catalyst Qilu Branch

Aluminum sol is a _commercially available product of Sinopec Catalyst Qilu Branch, and the _Al2O3 content is 21.5% by weight;

Kaolin is a commercial product of Suzhou China Kaolin Company, with a solid content of 78% by weight;

Pseudo-boehmite is a commercial product of Shandong Aluminum Factory, with a solid content of 60% by weight;

In embodiment and comparative example, the analytical testing method used is as follows:

Elemental content was determined by X-ray fluorescence spectrometry.

Unit cell constant and crystallinity are determined by X-ray diffraction (XRD) using RIPP145-90 and RIPP146-90 standard methods (see "Petrochemical Analysis Methods (RIPP Test Methods)", Yang Cuiding, etc., Science Press, 1990 edition) .

In the determination of the specific hydroxyl nest concentration, the thermogravimetric analysis data of the sample is determined by the thermogravimetric method described above.

The catalytic cracking catalyst microreaction activity (MA) was determined according to the RIPP 92-90 standard method.

The usage ratios described in the examples and comparative examples are weight ratios unless otherwise specified.

The acid-aluminum ratio is the weight ratio of hydrochloric acid with a concentration of 36% by weight to pseudo-boehmite calculated as alumina.

Example 1

(1) Preparation of modified molecular sieves

Use NaY molecular sieve as raw material to exchange with ammonium sulfate solution. The treatment conditions are: NaY molecular sieve (dry basis): ammonium sulfate: water = 1:1.0:8 (weight ratio), adjust the pH value to 3.5 with sulfuric acid, exchange at 85°C for 1 hour, wash . Hydrothermal roasting treatment, roasting temperature 580°C, 100% steam roasting time 2h. Treat the post-baked sample with a solution containing rare earth, the treatment conditions are: a baked molecular sieve (dry basis): rare earth chloride (according to RE ₂ O ₃ ): water = 1:0.042:8 (weight ratio), exchange at 70°C 1h, washed with deionized water. Hydrothermal roasting treatment, roasting temperature 580°C, 100% steam roasting time 2h. Treat the sample after secondary baking with a solution containing phosphoric acid and oxalic acid. The treatment conditions are: secondary baking molecular sieve (dry basis): phosphoric acid (according to P): oxalic acid (including two molecules of crystal water): water = 1:0.014:0.14:8 (weight ratio), adjust the pH value to 2.8 with sulfuric acid, treat at 70°C for 1 hour, filter; wash with deionized water. Hydrothermal calcination treatment, calcination temperature 550°C, 70% steam calcination time 2h, the modified molecular sieve was obtained, denoted as A1, and the physical and chemical properties characterization results are listed in Table 1.

(2) Preparation of catalytic cracking catalyst

20 parts by weight of pseudo-boehmite in terms of alumina is mixed with deionized water for beating, and adding a concentration of 36% by weight hydrochloric acid peptization to the obtained slurry, the acid-aluminum ratio (the acid-aluminum ratio is the concentration The weight ratio of 36% by weight of hydrochloric acid to pseudo-boehmite calculated as alumina, the same below) is 0.20, the temperature is raised to 65°C for acidification for 1 hour, and 30 parts by weight of kaolin slurry (solid content 45% by weight, the same below), 10 parts by weight of aluminum sol (the content of Al ₂ O ₃ is 21.5% by weight) based on alumina, stirred for 20 minutes, and then added 35 parts by weight of the aluminum sol based on dry basis. A1 molecular sieve, 5 parts by weight of Z2 molecular sieve (the second rare earth-containing Y-type molecular sieve) on a dry basis, and continued stirring for 30 minutes to obtain a slurry with a solid content of 30% by weight, which was spray-dried to make a microsphere catalyst. The microsphere catalyst was calcined at 500°C for 1 hour, and then washed with (NH ₄ ) ₂ SO ₄ solution at 60°C ((NH ₄ ) ₂ SO ₄ : microsphere catalyst: H ₂ O=0.04:1:10 weight ratio) until the Na ₂ O content is less than 0.25% by weight, and finally rinsed with deionized water, filtered and dried at 120°C to obtain catalytic cracking catalyst C1.

Comparative example 1

(1) Preparation of modified molecular sieves

Prepare modified Y molecular sieve according to the method of patent CN 101537366A.

Take 100 grams (dry basis) of NaY molecular sieve, pour it into a reaction kettle filled with 1000 g of exchange solution (containing 0.63% (NH4) ₂ HPO ₄ salt and 8.58% of NH ₄ Cl), exchange at 90°C for 1 hour, and at the same time During the exchange process, control the pH of the solution to 3.0-3.5, filter and wash after the exchange; after roasting for 2 hours at 730°C in the presence of 100% water vapor, pour the roasted product into a 1200g exchange solution (containing 0.58% RECl ₃ and 6.8% NH ₄ Cl salt) in a reactor, exchanged at 90°C for 1 hour, and controlled the solution pH=6.0-6.5 during the exchange process, filtered after exchange, washed, and roasted at 730°C for 2 hours in the presence of 70% water vapor to obtain The modified molecular sieve is denoted as B1, and the characterization results of its physical and chemical properties are listed in Table 1.

(2) Preparation of catalytic cracking catalyst

The catalytic cracking catalyst was prepared according to the method of step (2) in Example 1, except that the modified molecular sieve B1 was used instead of the modified molecular sieve A1 to obtain the catalytic cracking catalyst DC1.

Example 2

(1) Preparation of modified molecular sieves

Use NaY molecular sieve as raw material to exchange with ammonium chloride solution. The treatment conditions are: NaY molecular sieve (dry basis): ammonium chloride: water = 1:0.8:8, adjust the pH value to 4.0 with hydrochloric acid, exchange at 90°C for 1 hour, and wash. Hydrothermal roasting treatment, roasting temperature 550°C, 80% steam roasting time 2h. Treat the post-baked sample with phosphoric acid and fluosilicic acid solution, the treatment conditions are: a baked molecular sieve (dry basis): phosphoric acid (according to P): fluosilicic acid: water = 1: 0.01: 0.03: 8, hydrochloric acid to adjust pH2. 8. Exchange at 70°C for 1 hour, filter; wash with deionized water. Hydrothermal roasting treatment, roasting temperature 550°C, 70% steam roasting time 2h. Treat the sample after secondary roasting with a solution containing rare earth, the treatment conditions are: secondary roasting molecular sieve (dry basis): rare earth chloride (according to RE ₂ O ₃ ): water = 1:0.03:8, exchange at 70°C for 1 hour, and filter; Wash with deionized water. Hydrothermal calcination treatment, calcination temperature 550°C, 100% steam calcination time 2h, the modified molecular sieve was obtained, denoted as A2, the physical and chemical properties characterization results are listed in Table 1.

(2) Preparation of catalytic cracking catalyst

Mix 20 parts by weight of pseudoboehmite calculated as alumina with deionized water for beating, and add hydrochloric acid with a concentration of 36% by weight to the resulting slurry for peptization, with an acid-aluminum ratio of 0.20, and heat up to 65°C for acidification For 1 hour, add 30 parts by weight of kaolin slurry (solid content 45% by weight, the same below) on a dry basis and 10 parts by weight of aluminum sol in terms of alumina (Al ₂ O ₃ content is 21.5% by weight), Stir for 20 minutes, then add 25 parts by weight of the A2 molecular sieve, 13 parts by weight of the Z2 molecular sieve and 2 parts by weight of the Z3 molecular sieve to it on a dry basis, continue to stir and spray dry to make a microsphere catalyst. The microsphere catalyst was calcined at 500°C for 1 hour, and then washed with (NH ₄ ) ₂ SO ₄ solution at 60°C ((NH ₄ ) ₂ SO ₄ solution:microsphere catalyst:H ₂ O=0.04:1: 10) until the Na ₂ O content is less than 0.25% by weight, rinse with deionized water, filter and dry at 120°C to obtain catalytic cracking catalyst C2.

Comparative example 2

(1) Preparation of modified molecular sieves

Prepare modified Y molecular sieve according to the method of patent CN 101537366A.

Take 100 g (dry basis) of NaY molecular sieves and pour them into a reaction kettle containing 900 g of exchange solution (containing 0.45% by weight of (NH ₄ ) ₂ HPO ₄ salt and 10% by weight of (NH ₄ ) ₂ SO ₄ ). Exchange at 90°C for 1 hour, and at the same time control the pH of the solution to 3.0 to 3.5 during the exchange process, filter and wash after the exchange; after roasting at 730°C for 2 hours in the presence of 100% water vapor, pour the roasted product into a container containing 1200g of exchange solution (containing 0.44 % by weight of RECl ₃ and 7.8% by weight of NH ₄ Cl salt), exchanged at 90°C for 1 hour, and controlled the pH of the solution during the exchange process to be 6.0 to 6.5, filtered and washed after the exchange, at 730°C, 100 The modified molecular sieve was calcined for 2h in the presence of % water vapor, which is denoted as B2. The results of physical and chemical properties are listed in Table 1.

(2) Preparation of catalytic cracking catalyst

The catalytic cracking catalyst was prepared according to the method of step (2) in Example 2, except that the modified molecular sieve B2 was used instead of the modified molecular sieve A2 to obtain the catalytic cracking catalyst DC2.

Example 3

(1) Preparation of modified molecular sieves

Use NaY molecular sieve as raw material to exchange with ammonium sulfate solution. The treatment conditions are: NaY molecular sieve (dry basis): ammonium sulfate: water = 1:1.0:10, adjust the pH value to 3.5 with sulfuric acid, exchange at 90°C for 2 hours, and wash. Hydrothermal roasting treatment, roasting temperature 580°C, 100% steam roasting time 2h. Treat the post-baked sample with a solution containing phosphate and oxalic acid, the treatment conditions are: a baked molecular sieve (dry basis): diammonium hydrogen phosphate (according to P): oxalic acid: water = 1: 0.018: 0.03: 8, hydrochloric acid adjusted pH=3.0, exchange at 70°C for 1h, filter; wash with deionized water. Hydrothermal roasting treatment, roasting temperature 550°C, 100% steam roasting time 2h. Treat the sample after secondary roasting with a rare earth-containing solution. The treatment conditions are: secondary roasting molecular sieve (dry basis): rare earth chloride (according to RE ₂ O ₃ ): water = 1:0.02:8.0, exchange at 85°C for 1 hour, and filter; Wash with deionized water. Hydrothermal calcination treatment, calcination temperature 580°C, 100% water steam calcination time 2h, the modified molecular sieve was obtained, denoted as A3, and the physical and chemical properties characterization results are listed in Table 1.

(2) Preparation of catalytic cracking catalyst

20 parts by weight of pseudo-boehmite calculated as alumina is mixed with a certain amount of deionized water for beating, and hydrochloric acid peptization with a concentration of 36% by weight is added to the obtained slurry, the acid-aluminum ratio is 0.20, and the temperature is raised to 65 ℃ acidification for 1 hour, adding 30 parts by weight of kaolin slurry based on dry basis and 10 parts by weight of aluminum sol based on alumina (the content of Al ₂ O ₃ is 21.5% by weight), stirred for 20 minutes, and then added Add 15 parts by weight of the A3 molecular sieve and 25 parts by weight of the Z3 molecular sieve on a dry basis, continue to stir and spray dry to prepare a microsphere catalyst. The microsphere catalyst was calcined at 500°C for 1 hour, and then washed with (NH ₄ ) ₂ SO ₄ at 60°C ((NH ₄ ) ₂ SO ₄ : microsphere catalyst: H ₂ O=0.04:1:10) Until the Na ₂ O content is less than 0.25% by weight, rinse with deionized water, filter and dry at 120°C to obtain catalytic cracking catalyst C3.

Comparative example 3

(1) Preparation of modified molecular sieves

Prepare modified Y molecular sieve according to the method of patent CN 101537366A.

Take 100g (dry basis) NaY molecular sieve, pour it into a reaction kettle filled with 1000g exchange solution (containing 0.63% (NH ₄ ) ₂ HPO ₄ salt and 10% (NH ₄ ) ₂ SO ₄ ), at 90°C Exchange for 1 hour, and control the solution pH=3.0 to 3.5 during the exchange process, filter and wash after exchange; after roasting at 670°C for 2 hours in the presence of 100% water vapor, pour the roasted product into a container containing 400g of exchange solution (containing 0.60% RECl ₃ and 6.8% NH ₄ Cl salt), exchange at 90°C for 1 hour, and control the solution pH=6.0~6.5 during the exchange process, filter after exchange, wash, and store at 700°C in the presence of 100% water vapor After calcination for 2 hours, a modified molecular sieve was prepared, denoted as B3, and the characterization results of its physical and chemical properties are listed in Table 1.

(2) Preparation of catalytic cracking catalyst

The catalytic cracking catalyst was prepared according to the method of step (2) in Example 3, except that the modified molecular sieve B3 was used instead of the modified molecular sieve A3 to obtain the catalytic cracking catalyst DC3.

Example 4

(1) Preparation of modified molecular sieves

NaY molecular sieve is used as raw material to exchange ammonium phosphate and ammonium sulfate solution. The treatment conditions are: NaY molecular sieve (dry basis): ammonium dihydrogen phosphate (according to P): ammonium sulfate: water=1:0.05:1.0:8, sulfuric acid Adjust the pH value to 3.0, exchange at 85°C for 1h, and wash. Hydrothermal roasting treatment, roasting temperature 580°C, 100% steam roasting time 2h. Treat the post-baked sample with a solution containing oxalic acid, the treatment conditions are: a baked molecular sieve (dry basis): oxalic acid: water = 1: 0.15: 0.020: 8, exchange at 70°C for 1 hour, filter; wash with deionized water. Hydrothermal roasting treatment, roasting temperature 550°C, 100% steam roasting time 2h. Treat the sample after secondary roasting with rare earth-containing solution. The treatment conditions are: secondary roasting molecular sieve (dry basis): rare earth chloride (according to RE ₂ O ₃ ): water = 1:0.01:8, exchange at 70°C for 1 hour, and filter; Wash with deionized water. Hydrothermal calcination treatment, calcination temperature 600°C, 100% steam calcination time 2h, the modified molecular sieve was obtained, denoted as A4, and the physical and chemical properties characterization results are listed in Table 1.

(2) Preparation of catalytic cracking catalyst

20 parts by weight of pseudo-boehmite calculated as alumina is mixed with a certain amount of deionized water for beating, and hydrochloric acid peptization with a concentration of 36% by weight is added to the obtained slurry, the acid-aluminum ratio is 0.20, and the temperature is raised to 65 ℃ for 1 hour, add 28 parts by weight of kaolin slurry based on dry basis, and 10 parts by weight of aluminum sol based on alumina (Al ₂ O ₃ content is 21.5% by weight), stir for 20 minutes, and then add Add 40 parts by weight of the modified molecular sieve A4 and 2 parts by weight of Z2 molecular sieve on a dry basis, continue to stir and then spray dry to make a microsphere catalyst. The microsphere catalyst was calcined at 500°C for 1 hour, and then washed with (NH ₄ ) ₂ SO ₄ at 60°C ((NH ₄ ) ₂ SO ₄ : microsphere catalyst: H ₂ O=0.04:1:10) Until the Na ₂ O content is less than 0.25% by weight, rinse with deionized water, filter and dry at 120° C. to obtain catalytic cracking catalyst C4.

Comparative example 4

(1) Preparation of modified molecular sieves

Prepare modified Y molecular sieve according to the method of patent CN 101537366A.

Take 100 grams (dry basis) of NaY molecular sieves and pour them into a reaction kettle filled with 1200 grams of exchange solution (containing 1.22% (NH ₄ ) ₂ HPO ₄ salt and 8.58% NH ₄ Cl), exchange at 90°C for 1 hour, and at the same time During the exchange process, the pH of the solution is controlled to be 5.0-5.5, filtered and washed after the exchange; after roasting at 620°C for 2 hours in the presence of 100% water vapor, pour the roasted product into a 1200g exchange solution (containing 0.055% RECl ₃ and 7.8 % NH ₄ Cl salt) reaction kettle, exchanged at 90°C for 1h, and controlled the solution pH=6.0-6.5 during the exchange process, filtered, washed, and roasted at 700°C for 2h in the presence of 100% water vapor to prepare The obtained modified molecular sieve is denoted as B4, and the characterization results of physical and chemical properties are listed in Table 1.

(2) Preparation of catalytic cracking catalyst

The catalytic cracking catalyst was prepared according to the method of step (2) in Example 4, except that the modified molecular sieve B4 was used instead of the modified molecular sieve A4 to obtain the catalytic cracking catalyst DC4.

Example 5

(1) Preparation of modified molecular sieves

Use NaY molecular sieve as raw material to exchange ammonium phosphate and ammonium sulfate solution. The treatment conditions are: NaY molecular sieve (dry basis): ammonium dihydrogen phosphate (according to P): ammonium sulfate: water=1:0.05:1.0:8, sulfuric acid Adjust the pH value to 3.5, exchange at 90°C for 2 hours, and wash. Hydrothermal roasting treatment, roasting temperature 550°C, 100% steam roasting time 2h. Treat the post-baked sample with a solution containing rare earth, the treatment conditions are: a baked molecular sieve (dry basis): rare earth chloride (according to RE ₂ O ₃ ): water = 1:0.02:8.0, hydrochloric acid to adjust pH2.9, 85 Exchange at ℃ for 1h, filter; wash with deionized water. Hydrothermal roasting treatment, roasting temperature 580°C, 100% steam roasting time 2h. Treat the sample after secondary baking with a solution containing phosphate and fluorosilicic acid. The treatment conditions are: secondary baking molecular sieve (dry basis): diammonium hydrogen phosphate (according to P): fluorosilicic acid: water = 1: 0.006: 0.03: 8. Adjust the pH to 3.0 with hydrochloric acid, exchange at 70°C for 1 hour, filter, and wash with deionized water. Hydrothermal calcination treatment, calcination temperature 550°C, 100% water steam calcination time 2h, the modified molecular sieve was obtained, denoted as A5, the physical and chemical properties characterization results are listed in Table 1.

(2) Preparation of catalytic cracking catalyst

20 parts by weight of pseudo-boehmite calculated as alumina is mixed with a certain amount of deionized water for beating, and hydrochloric acid peptization with a concentration of 36% by weight is added to the obtained slurry, the acid-aluminum ratio is 0.20, and the temperature is raised to 65 ℃ acidification for 1 hour, adding 30 parts by weight of kaolin slurry based on dry basis and 10 parts by weight of aluminum sol based on alumina (the content of Al ₂ O ₃ is 21.5% by weight), stirred for 20 minutes, and then added Add 5 parts by weight of the modified molecular sieve A5, 30 parts by weight of Z3 molecular sieve and 5 parts by weight of DASY-2.0 molecular sieve on a dry basis, continue stirring and then spray dry to prepare a microsphere catalyst. The microsphere catalyst was calcined at 500°C for 1 hour, and then washed with (NH ₄ ) ₂ SO ₄ at 60°C ((NH ₄ ) ₂ SO ₄ : microsphere catalyst: H ₂ O=0.04:1:10) Until the Na ₂ O content is less than 0.25% by weight, rinse with deionized water, filter and dry at 120°C to obtain catalytic cracking catalyst C5.

Comparative example 5

(1) Preparation of modified molecular sieves

Prepare modified Y molecular sieve according to the method of patent CN 101537366A.

Take 100 grams (dry basis) of NaY molecular sieves and pour them into a reaction kettle filled with 1500 g of exchange solution (containing 1.11% (NH ₄ ) ₂ HPO ₄ salt and 8.58% NH ₄ Cl), exchange at 90°C for 1 hour, and at the same time During the exchange process, the pH of the solution is controlled to be 4.5-5.0, filtered and washed after the exchange; after roasting at 650°C for 2 hours in the presence of 100% water vapor, pour the roasted product into a 1000g exchange solution (containing 0.35% RECl ₃ and 7.8 % NH ₄ Cl salt) reaction kettle, exchanged at 90°C for 1h, and controlled the solution pH=6.0-6.5 during the exchange process, filtered after exchange, washed, and roasted at 700°C for 2h in the presence of 70% water vapor to prepare The obtained modified molecular sieve is denoted as B5, and the physicochemical property characterization results are listed in Table 1.

(2) Preparation of catalytic cracking catalyst

A catalytic cracking catalyst was prepared according to the method of step (2) in Example 5, except that the modified molecular sieve B5 was used instead of the modified molecular sieve A5 to obtain a catalytic cracking catalyst DC5.

Comparative example 6

The catalytic cracking catalyst was prepared according to the method of Example 1, and the A1 molecular sieve in Example 1 was replaced by an equal amount of Z3 molecular sieve, which was recorded as DC6.

Table 1

test case 1

This test example illustrates the cracking reaction performance of the catalytic cracking catalyst of the present invention.

The above catalytic cracking catalysts C1-C5 and DC1-DC6 were aged at 800°C and 100% steam for 8 hours, and the reaction performance of the catalysts was determined by a small fixed fluidized bed ACE R+ device (designed and manufactured by Kayser Technology Inc., USA) For evaluation, the loading amount of the catalyst was 9 g. Under the conditions of a reaction temperature of 518°C, a space velocity of 16h ^-1 , and a catalyst-to-oil ratio (weight) of 5.5, the catalytic mixed oil shown in Table 2 was used as feedstock oil and injected into the ACE R+ device for catalytic cracking reaction. The results as shown in Table 3.

Table 2

Density, g/cm ³ (20℃) 0.8994 Viscosity (100C), mm ² /s 5.63 Freezing point, ℃ 34 Carbon residue, wt% 0.25 Element content, wt% C 87.08 h 12.57 S 0.23 N 0.12 Metal content, μg/g Ca 0.4 Fe 0.2 Na 0.6 Ni <0.1 V <0.1 Distillation range, ℃ initial boiling point 265 10% 333 50% 426 70% 470 95% 564

table 3

As can be seen from the data in Table 3, the catalytic cracking catalyst of the present invention shows a relatively high utilization rate of heavy oil, higher gasoline selectivity, and good coke selectivity (low coke selectivity); the total yield of gasoline and diesel oil Higher, lower coke yield.

test case 2

This test example illustrates the hydrothermal structural stability of the modified Y molecular sieve of the present invention.

The phosphorus and rare earth modified Y-type molecular sieve samples prepared in the above-mentioned Examples 2, 3, 4 and Comparative Examples 2, 3, 4 were subjected to 2 hours, 4 hours, 8 hours, After 17 hours and 24 hours of hydrothermal aging treatment, the crystallinity was measured, and the results of crystallinity and crystal retention are shown in Figure 1 and Figure 2.

It can be seen from Fig. 1 and Fig. 2 that the crystallinity and crystal retention of the modified Y molecular sieve according to the present invention are significantly higher than those of the comparative example after hydrothermal aging treatment. It shows that the modified Y molecular sieve provided by the present invention has better hydrothermal structure stability.

Test case 3

This example illustrates the hydrothermal activity stability and coke selectivity of the modified Y molecular sieve of the present invention.

The samples prepared in the above-mentioned Examples 2, 5 and Comparative Examples 2, 5 were subjected to hydrothermal aging treatment for 2 hours, 4 hours, 8 hours, 17 hours, and 24 hours respectively at 800 ° C and 100% water vapor conditions, and the light weight was measured. Oil Microreactive Activity (MA), and Coke Yield, Calculate Coke Conversion Ratio. The results are shown in Figure 3 and Figure 4.

Example 6

The catalyst was prepared according to the method of Example 1, except that the Z2 molecular sieve was replaced by an equal amount of Z3 molecular sieve, which was denoted as C6.

Example 7

The catalyst was prepared according to the method of Example 1, except that an equal amount of Z3 molecular sieve was used instead of Z2 molecular sieve, denoted as C7.

Claims (12)

1. A catalytic cracking catalyst for producing gasoline by reducing the coke yield, containing 10% to 50% by weight of modified Y-type molecular sieves on a dry basis, and no more than 30% by weight on a dry basis of specific rare earth-containing Y-type Molecular sieve, 10% to 70% by weight of clay based on dry basis and 10% to 40% by weight of inorganic oxide binder based on oxide; the modified Y-type molecular sieve: the unit cell constant is 2.420 to 2.440 nm, by weight percentage, P is 0.05% to 6%, RE ₂ O ₃ is 0.03% to 10%, aluminum oxide is less than 22%, and the specific hydroxyl nest concentration is less than 0.35mmol/g. In the formula, M _200°C , M _500°C and M _800°C represent the percentage of weight loss measured at the temperature of 200°C, 500°C and 800°C respectively, and C is the crystallinity of the sample; The specific rare earth-containing Y-type molecular sieve is a rare earth-modified gas-phase ultrastable Y-type molecular sieve and/or a rare-earth-containing acid-treated hydrothermal dealuminated Y-type molecular sieve. 2. according to the described catalytic cracking catalyst of claim 1, it is characterized in that, the unit cell constant of described modified Y-type molecular sieve is 2.428nm～2.438nm, P content is 0.1%～4.5% by weight percentage, RE ₂ O ₃ The content is 0.1%-4.5%, the alumina content is less than 21%, and the specific hydroxyl nest concentration is less than 0.3mmol/g. 3. The catalytic cracking catalyst according to claim 1, characterized in that, the catalyst comprises 0.5% to 30% by weight of the specific rare earth-containing Y-type molecular sieve. 4. the preparation method of the catalytic cracking catalyst described in any one of claim 1～3, this method comprises preparation described modified Y-type molecular sieve, with prepared modified Y-type molecular sieve, described specific rare earth-containing The steps of mixing and beating Y-type molecular sieve, clay and inorganic oxide binder, and spray drying; the modified Y-type molecular sieve uses NaY molecular sieve as raw material, and adopts three exchange procedures and three times with rare earth-containing substances and phosphorus-containing substances. It is obtained by hydrothermal treatment, wherein the rare earth-containing substance and the phosphorus-containing substance are exchanged by adding a phosphorus-containing substance exchange solution and a rare-earth substance-containing exchange solution for exchange, and the phosphorus-containing substance is added once or several times in any exchange process, and the rare-earth substance Add in any exchange process other than one exchange. 5. according to the preparation method of the described catalytic cracking catalyst of claim 4, it is characterized in that, in the described exchange process, further comprise adding dealumination agent and carry out chemical dealumination to promote the removal of aluminum, chemical dealumination process is in an exchange process. In any other exchange process. 6. according to the preparation method of catalytic cracking catalyst described in claim 4, it is characterized in that, described phosphorus-containing material is selected from orthophosphoric acid, phosphorous acid, pyrophosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate and One or more of aluminum phosphates. 7. according to the preparation method of catalytic cracking catalyst described in claim 4, it is characterized in that, described rare earth-containing substance is selected from the group consisting of lanthanum oxide, cerium oxide, lanthanum nitrate, cerium nitrate, lanthanum chloride, cerium chloride, nitric acid mixed One or more of rare earths and chlorinated mixed rare earths. 8. according to the preparation method of catalytic cracking catalyst described in claim 5, it is characterized in that, described dealumination agent is selected from ethylenediaminetetraacetic acid, oxalic acid, citric acid, sulfosalicylic acid, fluosilicic acid, hydrochloric acid , sulfuric acid, nitric acid, ammonium oxalate, ammonium fluoride, ammonium fluorosilicate, and ammonium fluoroborate. 9. according to the preparation method of the catalytic cracking catalyst described in any one of claim 4～8, it is characterized in that, the preparation method of described modified Y type molecular sieve comprises the steps: 1) NaY molecular sieve, ammonium salt, ammonium phosphate salt and water are mixed according to the weight ratio of NaY molecular sieve: ammonium salt: ammonium phosphate salt: water = 1: 0.4～1.0: 0～0.04: 5～10 to obtain a slurry, which is adjusted with inorganic acid The pH value of the slurry is 3.0 to 4.5, and then it is treated at 70°C to 95°C for at least 0.5h and then washed, wherein the NaY molecular sieve is calculated on a dry basis, and the ammonium phosphate salt is calculated as elemental phosphorus; the ammonium phosphate salt is phosphorus-containing ammonium salt; 2) Calcining the product obtained in step 1) at a temperature of 350° C. to 650° C. in an atmosphere of 1% to 100% water vapor for at least 0.5 h to obtain a roasted molecular sieve; 3) Mix the one-baking molecular sieve obtained in step 2) with phosphoric acid and dealumination agent according to the weight ratio of one-baking molecular sieve: phosphoric acid: dealumination agent: water=1:0～0.04:0.02～0.3:5～10, and use inorganic Adjust the pH value to 2.4 to 3.5 with acid, and then treat it at 50°C to 90°C for at least 0.5 hours, filter and wash, and the washing water temperature is ≥50°C, wherein, the one-baked molecular sieve is calculated on a dry basis, and the phosphoric acid is calculated on an elemental phosphorus basis; 4) Calcining the product obtained in step 3) at a temperature of 350° C. to 650° C. in an atmosphere of 1% to 100% water vapor for at least 0.5 h to obtain a double-calcined molecular sieve; 5) Mix the two-baked molecular sieve obtained in step 4) with rare earth chloride and water according to the weight ratio of two-baked molecular sieve: rare earth chloride: water = 1: 0.01-0.05: 5-10, and then mix them at 70°C-90°C Treat for at least 0.5 hours, filter; wash, wash water temperature ≥ 50 ° C, wherein, the dibaking molecular sieve is calculated on a dry basis, and the rare earth chloride is calculated as RE ₂ O ₃ ; 6) Calcining the product obtained in step 5) at 350° C. to 650° C. in an atmosphere of 1% to 100% water vapor for at least 0.5 h to obtain a modified Y-type molecular sieve. 10. according to the preparation method of catalytic cracking catalyst described in claim 9, it is characterized in that, described binding agent is selected from γ-alumina, η-alumina, θ-alumina, χ-alumina, quasi-thin One or more of Pseudoboemite, Boehmite, Gibbsite or Bayerite; the clay is selected from kaolin, montmorillonite, diatom One or more of soil, saponite, retortite, sepiolite, attapulgite, hydrotalcite, and bentonite. 11. according to the preparation method of catalytic cracking catalyst described in claim 10, it is characterized in that, described kaolin is halloysite. 12. according to the preparation method of the described catalytic cracking catalyst of claim 4, it is characterized in that, described binding agent is selected from γ-alumina, η-alumina, θ-alumina, χ-alumina, quasi-thin One or more of Pseudoboemite, Boehmite, Gibbsite or Bayerite; the clay is selected from kaolin, montmorillonite, diatom One or more of soil, saponite, retortite, sepiolite, attapulgite, hydrotalcite, and bentonite.