Catalytic cracking combined catalyst, its preparation method and application

Abstract

The present application relates to the technical field of pyrolysis catalyst preparation, and discloses a catalytic pyrolysis combined catalyst and a preparation method thereof. 3 The bulk density of the catalyst B is 0.81-0.87 g / cm 3 The bulk density ratio of the catalyst A to the catalyst B is 0.88-0.95; and the weight ratio of the Y-type molecular sieve contained in the catalyst A and the catalyst B is 2-4:1. The combined catalyst has good anti-wear performance, high low-carbon olefin yield and propylene selectivity in heavy oil catalytic cracking, and can improve the low-carbon olefin yield without increasing the heavy oil and diesel yield.

Description

Technical Field

[0001] This invention relates to the field of cracking catalyst preparation technology, specifically to a combined catalytic cracking catalyst, its preparation method, and its application. Background Technology

[0002] The impact of new energy vehicles on the traditional fuel vehicle market: my country's refined oil market is approaching saturation, diesel consumption has passed its peak, gasoline consumption is approaching its peak, and aviation kerosene still has some room for growth.

[0003] Driven by increasing global demand for chemical products, particularly for chemical feedstocks such as ethylene and propylene, the development of catalytic cracking technology for producing chemicals can effectively improve catalytic cracking technologies that primarily produce fuel oil. By improving reaction conditions or replacing catalysts, product distribution can be controlled, and the modification cost is relatively low. Catalytic cracking catalyst technology is currently the core technology for the transition from oil refining to chemical processing. However, conventional catalytic cracking catalysts have low yields of low-carbon olefins, making it difficult to meet market demands. Therefore, developing catalytic cracking catalysts capable of processing heavy oil and producing higher yields of low-carbon olefins is essential.

[0004] CN111718231A discloses a method for the direct catalytic conversion of crude oil to ethylene and propylene, which uses different catalysts for light oil and heavy oil respectively. The light oil uses a catalyst with Y and ZSM-5 molecular sieves as the main active components, while the heavy oil uses a catalyst with a mixture of multiple molecular sieves as the main active components. The steps are complicated and cannot simultaneously catalytically crack light oil and heavy oil.

[0005] CN112642472B discloses an aluminum sol binder catalyst for the conversion of hydrocarbon oil to produce low-carbon olefins and BTX, its preparation method, and its application. The catalyst uses FAU-structured molecular sieves and IMF-structured molecular sieves as the main active components. However, as the main catalyst, it is difficult to further improve the yield of low-carbon olefins during catalytic cracking. Furthermore, most current catalysts for the catalytic cracking of heavy oil to low-carbon olefins mainly use a mixture of a traditional catalytic cracking main catalyst and a small amount of low-carbon olefin-enhancing co-catalyst to reduce secondary reactions such as hydrogen transfer in low-carbon olefin products. However, current mixed catalysts formed by adding propylene co-catalysts to catalytic cracking catalysts, while increasing propylene yield, reduce the conversion capacity of heavy oil and diesel, resulting in a lower heavy oil conversion rate and a higher diesel yield.

[0006] Therefore, there is a need to develop a catalytic cracking catalyst that can improve the yield of propylene without reducing the conversion capacity of heavy oil and diesel. Summary of the Invention

[0007] The purpose of this invention is to overcome the problem that existing catalytic cracking catalysts have low conversion rates of heavy oil and diesel oil while improving the yield of low-carbon olefins. This invention provides a combined catalytic cracking catalyst, its preparation method, and its application. This combined catalyst has good wear resistance, high propylene selectivity, and improves the yield of low-carbon olefins while basically not increasing the yield of heavy oil and diesel oil.

[0008] To achieve the above objectives, a first aspect of the present invention provides a catalytic cracking combined catalyst, wherein the combined catalyst comprises catalyst A and catalyst B; wherein the bulk density of catalyst A is 0.7-0.79 g / cm³. 3 The bulk density of catalyst B is 0.81-0.87 g / cm³. 3 The bulk density ratio of catalyst A to catalyst B is 0.88-0.95.

[0009] The Y-type molecular sieve contained in catalyst A and catalyst B are in a dry weight ratio of 2-4:1.

[0010] A second aspect of the present invention provides a method for preparing a catalytic cracking combined catalyst, wherein the method includes:

[0011] (1) The molecular sieve, the first binder and water are pulped to obtain a pre-bonded molecular sieve slurry;

[0012] (2) Mix clay, second binder, inorganic acid and water thoroughly to form a matrix slurry, and then mature it;

[0013] (3) The pre-bonded molecular sieve slurry is thoroughly mixed with the matured matrix slurry, and then the remaining first binder is added and mixed evenly to obtain the catalyst slurry;

[0014] (4) The catalyst slurry is homogenized, spray-dried and calcined to obtain catalyst A or catalyst B;

[0015] (5) Mix catalyst A and catalyst B to obtain the combined catalyst;

[0016] The bulk density of catalyst A is 0.7-0.79 g / cm³. 3 The bulk density of catalyst B is 0.81-0.87 g / cm³. 3 The bulk density ratio of catalyst A to catalyst B is 0.88-0.95.

[0017] The Y-type molecular sieve contained in catalyst A and catalyst B are in a dry weight ratio of 2-4:1.

[0018] The third aspect of the present invention provides the application of a catalytic cracking combined catalyst prepared by the catalytic cracking combined catalyst described in the first aspect or by the method described in the second aspect in the heavy oil cracking cracking.

[0019] Through the above technical solution, the present invention can achieve the following technical effects:

[0020] (1) The catalytic cracking combined catalyst provided by the present invention reduces the content of Y-type molecular sieve in catalyst B and reduces the bulk density difference between catalyst A and catalyst B, which is beneficial to promote the conversion of heavy oil and diesel on the catalyst surface, avoids the problem of increasing the yield of heavy oil and diesel in the catalyst due to the addition of high bulk density ratio components in the traditional method, and more efficiently converts into gasoline diffuse to the molecular sieve active center, thereby improving the yield of low carbon olefins.

[0021] (2) The catalytic cracking combined catalyst provided by the present invention is prepared by adding the first binder and the second binder in steps, thereby reducing the amount of binder used; and the silicon-aluminum ratio in the Y molecular sieve is relatively low, which is more conducive to the combination with the binder. The prepared catalyst has good strength, low wear index and small deviation, and strong wear resistance.

[0022] (3) The catalytic cracking combined catalyst provided by the present invention satisfies the requirement of increasing the yield of low-carbon olefins while keeping the yield of heavy oil and diesel unchanged during the heavy oil catalytic cracking process. It has a high conversion rate, propylene selectivity and propylene yield, and a high propylene concentration in liquefied gas, resulting in a significant improvement in overall economic benefits. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] The first aspect of this invention provides a catalytic cracking combined catalyst, characterized in that the combined catalyst comprises catalyst A and catalyst B; wherein the bulk density of catalyst A is 0.7-0.79 g / cm³. 3 The bulk density of catalyst B is 0.81-0.87 g / cm³. 3 The bulk density ratio of catalyst A to catalyst B is 0.88-0.95.

[0025] The Y-type molecular sieve contained in catalyst A and catalyst B are in a dry weight ratio of 2-4:1.

[0026] In this invention, the bulk density ratio of catalyst A to catalyst B is 0.88-0.95, for example, 0.88, 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, or any value within any range of two such values; the weight ratio of Y-type molecular sieves contained in catalyst A and catalyst B, on a dry basis, is 2-4:1, for example, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, or any value within any range of two such values. Controlling the bulk density of catalyst A, the bulk density of catalyst B, the bulk density ratio of catalyst A to catalyst B, and the weight ratio of Y-type molecular sieves contained in catalyst A and catalyst B, on a dry basis, within these ranges is beneficial for achieving, during the heavy oil catalytic cracking process, increased yield of low-carbon olefins while maintaining the conversion rate of heavy oil and diesel oil, exhibiting high propylene selectivity, and demonstrating high strength and good catalytic effect in the catalytic cracking combination catalyst.

[0027] In some embodiments of the present invention, preferably, the weight ratio of catalyst A to catalyst B is 1-9:1, more preferably 7-26:3. Controlling the weight ratio of catalyst A to catalyst B within the above range in the present invention is beneficial for obtaining a combined catalytic cracking catalyst with higher yield of low-carbon olefins and propylene selectivity, while maintaining the conversion rates of heavy oil and diesel oil. Within the preferred range, this is beneficial for the combined catalyst to have better catalytic performance. When the weight ratio of catalyst A to catalyst B is less than 1:1, the resulting combined catalyst has a lower propylene yield but increased yields of heavy oil and diesel oil.

[0028] In some embodiments of the present invention, preferably, the pore volume of the catalyst A is 0.31-0.37 cm³. 3 / g; the pore volume of catalyst B is 0.29-0.31 cm³. 3 / g. In this invention, controlling the pore volumes of catalyst A and catalyst B within the above-mentioned range is beneficial to achieving better catalytic performance in the resulting combined catalyst.

[0029] In some embodiments of the present invention, preferably, the catalyst A contains a Y-type molecular sieve, modified ZSM-5, a binder, and clay; wherein, based on the dry weight of the catalyst A, the catalyst A contains: 10-25% by weight of Y-type molecular sieve, 15-35% by weight of modified ZSM-5, 15-27% by weight of binder, and 30-50% by weight of clay.

[0030] In some embodiments of the present invention, preferably, the catalyst B contains Y-type molecular sieve, modified ZSM-5, binder and clay; wherein, based on the dry weight of catalyst B, the catalyst B contains: 3-8% by weight of Y-type molecular sieve, 25-40% by weight of modified ZSM-5, 15-27% by weight of binder and 30-50% by weight of clay.

[0031] In this invention, controlling the contents of Y-type molecular sieve, modified ZSM-5, binder and clay in catalyst A and catalyst B within the above range is beneficial to obtaining catalyst A and catalyst B with the required bulk density and bulk density ratio. This allows the obtained catalytic cracking combined catalyst to avoid the problem of increased heavy oil and diesel yield, and improve the yield of low-carbon olefins and propylene selectivity.

[0032] A second aspect of the present invention provides a method for preparing a catalytic cracking combined catalyst, wherein the method includes:

[0033] (1) Y-type molecular sieve, modified ZSM-5, part of the first binder and water are pulped to obtain pre-bonded molecular sieve slurry;

[0034] (2) Mix clay, second binder, inorganic acid and water thoroughly to form a matrix slurry, and then mature it;

[0035] (3) The pre-bonded molecular sieve slurry is thoroughly mixed with the matured matrix slurry, and then the remaining first binder is added and mixed evenly to obtain the catalyst slurry;

[0036] (4) The catalyst slurry is homogenized, spray-dried and calcined to obtain catalyst A or catalyst B;

[0037] (5) Mix catalyst A and catalyst B to obtain the combined catalyst;

[0038] The bulk density of catalyst A is 0.7-0.79 g / cm³. 3 The bulk density of catalyst B is 0.81-0.87 g / cm³. 3 The bulk density ratio of catalyst A to catalyst B is 0.88-0.95.

[0039] The Y-type molecular sieve contained in catalyst A and catalyst B are in a dry weight ratio of 2-4:1.

[0040] In this invention, the catalyst A and catalyst B prepared by the method of preparation have good compatibility, and the wear intensity between catalyst A and catalyst B is small, thereby reducing the wear consumption between the two catalysts.

[0041] In some embodiments of the present invention, preferably, in the preparation method of catalyst A, the weight ratio of Y-type molecular sieve and modified ZSM-5 in the pre-bonded molecular sieve slurry on a dry basis is (2-5):(3-7).

[0042] In some embodiments of the present invention, preferably, in the preparation method of catalyst B, the weight ratio of Y-type molecular sieve and modified ZSM-5 in the pre-bonded molecular sieve slurry on a dry basis is (3-8):(25-40).

[0043] In some embodiments of the present invention, preferably, the Y-type molecular sieve is selected from ReUSY-type and / or USY-type molecular sieves.

[0044] In some embodiments of the present invention, preferably, the silicon-to-aluminum ratio (SiO2 / Al2O3) of the Y-type molecular sieve is 3.1-5. In this invention, the low silicon-to-aluminum ratio of the Y-type molecular sieve is beneficial for bonding with the binder, thereby improving the wear resistance of the catalytic cracking composite catalyst.

[0045] In some embodiments of the present invention, preferably, the Re2O3 content in the ReUSY-type molecular sieve is ≤3wt%. In the present invention, controlling the Re2O3 content in the ReUSY-type molecular sieve within the above range is beneficial for ensuring the hydrothermal stability of the catalyst while reducing the catalyst's hydrogen transfer capacity and improving the yield of low-carbon olefin products.

[0046] In some embodiments of the present invention, preferably, the modifying element contained in the modified ZSM-5 is selected from at least one of phosphorus, alkaline earth metal elements and transition metal elements, and preferably at least two.

[0047] In some embodiments of the present invention, preferably, the alkaline earth metal element is Mg.

[0048] In some embodiments of the present invention, preferably, the transition metal element is selected from at least one of Fe, Co, Ni, Zn and Cu;

[0049] In some embodiments of the present invention, preferably, the content of the modifying element in the modified ZSM-5, calculated as oxide, is 1.5-5 wt%.

[0050] In some embodiments of the present invention, preferably, the first binder is selected from at least one of silica sol, alumina sol, and boehmite, and more preferably alumina sol and / or alumina sol. In the present invention, the first binder serves as a molding aid. The catalytic cracking composite catalyst obtained by combining the first binder with Y-type molecular sieves and modified ZSM-5 can improve the cracking of large molecular hydrocarbons in the matrix for heavy oil catalytic cracking, exhibiting good catalytic cracking effect and simultaneously improving the yield of low-carbon olefins while maintaining the yields of heavy oil and diesel oil.

[0051] In this invention, in step (1), during the process of mixing Y-type molecular sieve, modified ZSM-5, a portion of the first binder and water to obtain a pre-bonded molecular sieve slurry, the amount of water used is not particularly limited, as long as the Y-type molecular sieve, modified ZSM-5 and a portion of the first binder can be fully mixed to obtain the pre-bonded molecular sieve slurry. For example, based on the total amount of the pre-bonded molecular sieve slurry, the amount of water used is 35-40% by weight; in addition, the water is not specifically limited, but deionized water is preferred.

[0052] In some embodiments of the present invention, preferably, the second binder is selected from at least one of silica sol, alumina sol and boehmite, and more preferably boehmite.

[0053] In some embodiments of the present invention, preferably, the weight ratio of the first adhesive to the second adhesive, on a dry basis, is (7-12):(8-15).

[0054] In some embodiments of the present invention, preferably, the first adhesive is a portion of the first adhesive and the remainder of the first adhesive.

[0055] In some embodiments of the present invention, preferably, the weight ratio of the portion of the first adhesive to the remaining first adhesive is 1:1-9 on a dry basis.

[0056] In some embodiments of the present invention, preferably, the clay is selected from at least one of kaolin, halloysite and bentonite, and preferably kaolin.

[0057] In some embodiments of the present invention, preferably, on a dry basis, the weight ratio of the clay to the second binder is (30-50):(8-15).

[0058] In some embodiments of the present invention, preferably, the inorganic acid is selected from at least one of hydrochloric acid, nitric acid, and sulfuric acid.

[0059] In some embodiments of the present invention, preferably, the inorganic acid (in the form of H+) +The molar ratio of the first binder (on a dry basis) to the second binder (on a dry basis) is 0.1-0.5:1. In this invention, the addition of an inorganic acid to the second binder for appropriate dissolution is beneficial to improving the fluidity of the formed matrix slurry.

[0060] In this invention, in step (2), clay, a second binder, and an inorganic acid are mixed to form a matrix slurry. The mixing method is not specifically limited, but preferably, the mixing is carried out under stirring conditions. These stirring conditions are not specifically limited; for example, they can be carried out at a stirring speed of 100-150 r / min. The amount of water used in forming the matrix slurry is not particularly limited, as long as the clay, second binder, and inorganic acid are sufficiently mixed to obtain the matrix slurry. For example, based on the total amount of the matrix slurry, the amount of water used is 35-40% by weight. Furthermore, the amount of water is not specifically limited, but deionized water is preferred.

[0061] In some embodiments of the present invention, preferably, in step (4), the spray drying temperature is 370-450℃ and the time is 0.05-10 min; the calcination temperature is 400-550℃ and the time is 0.5-2 h. In the present invention, the heating rate from room temperature to the set calcination temperature is 5-15℃ / min, and the calcination atmosphere is air. In the present invention, controlling the temperature and time of spray drying and calcination within the above range is beneficial to the drying and calcination of the catalyst slurry, and beneficial to the formation of a catalyst with better strength. This catalyst can improve the yield of low-carbon olefins while ensuring that the yield of heavy oil and diesel remains basically unchanged during the catalytic cracking of heavy oil. Preferably, the mixing is carried out under stirring conditions, wherein the stirring conditions are not specifically limited, for example, it can be carried out under stirring conditions of 50-70 r / min.

[0062] In this invention, preferably, in step (5), the mixing process of catalyst A and catalyst B includes, but is not limited to, one or more of the mixing methods such as grinding, sieving, and stirring. Preferably, the mixing is carried out under stirring conditions, wherein the stirring conditions are not specifically limited, for example, it can be carried out under stirring conditions of 50-70 r / min.

[0063] In this invention, the method of adding a portion of the first binder, the remaining first binder, and the second binder in stages is beneficial to increasing the wear resistance of the catalytic cracking combined catalyst.

[0064] The third aspect of the present invention provides the application of a catalytic cracking combined catalyst prepared by the catalytic cracking combined catalyst described in the first aspect or by the method described in the second aspect in the catalytic cracking of heavy oil.

[0065] In this invention, unless otherwise specified, all quantities of materials are on a dry basis.

[0066] The present invention will be described in detail below through embodiments:

[0067] The main analytical method of this invention:

[0068] Pore ​​volume test: determined according to the standard method of NB / SH / T 0955;

[0069] Bulk density test: determined according to the standard method of NB / SH / T 0954;

[0070] Wear index test: determined according to the standard method of NB / SH / T 0964;

[0071] Microreaction activity test: determined according to the standard method of NB / SH / T 0952;

[0072] Performance evaluation: The reaction performance was evaluated using an ACE device. All feedstock oils used were ACE standard oils, and their properties are shown in Table 1. The catalyst was aged at 800℃ and 100% (v / v) steam for 17 hours before evaluation. The catalytic reaction temperature was 530℃, and the catalyst-to-oil ratio was 6.

[0073] Conversion rate (wt%) = 100 (wt%) - Heavy oil yield (wt%) - Diesel yield (wt%);

[0074] C2-C4 olefin yield (wt%) = ethylene yield (wt%) + propylene yield (wt%) + butene yield (wt%);

[0075] Propylene selectivity (wt%) = Propylene yield (wt%) × 100 (wt%) / LPG yield (wt%).

[0076] The main raw materials and their sources in this invention are as follows:

[0077] ReUSY-1 molecular sieve: purchased from Lanzhou Petrochemical Catalyst Plant, industrial grade, rare earth content (as Re2O3) is 2.5wt%, silicon-aluminum ratio (SiO2 / Al2O3 molar ratio) is 3.3;

[0078] ReUSY-2 molecular sieve: purchased from Lanzhou Petrochemical Catalyst Plant, industrial grade, rare earth content (as Re2O3) is 3wt%, silicon-aluminum ratio (SiO2 / Al2O3 molar ratio) is 3.2;

[0079] USY type molecular sieve: purchased from Lanzhou Petrochemical Catalyst Plant, industrial grade, with a silicon-to-aluminum ratio (SiO2 / Al2O3) of 3.2;

[0080] Modified ZSM-5: purchased from Lanzhou Petrochemical Catalyst Plant, with a phosphorus content (as P2O5) of 2.5 wt% and a zinc content (as ZnO) of 0.5 wt%.

[0081] Silica sol: purchased from Lanzhou Petrochemical Catalyst Plant, with a solid content of 30% by weight;

[0082] Aluminum sol: purchased from Lanzhou Petrochemical Catalyst Plant, solid content 20% by weight;

[0083] Boehmite: purchased from Lanzhou Petrochemical Catalyst Plant, industrial grade, solid content 69% by weight;

[0084] Kaolin: Purchased from Lanzhou Petrochemical Catalyst Plant, industrial grade, solid content 71% by weight;

[0085] Hydrochloric acid: purchased from Sinopharm Group, analytical grade, concentration 36% by weight.

[0086] Example 1

[0087] Preparation of catalyst A:

[0088] (1) Add ReUSY-1 molecular sieve, P-Zn modified ZSM-5, and aluminum sol to deionized water and mix evenly. Pulp for 60 min to obtain pre-bonded molecular sieve slurry. The amount of aluminum sol is 40% of the total amount of aluminum sol on a dry basis.

[0089] (2) Under stirring conditions, kaolin, pseudoboehmite, and hydrochloric acid were added to deionized water, mixed evenly, and then matured at 60°C for 1 hour to obtain a matrix slurry. The added hydrochloric acid (in H2O) was... + The molar ratio of (calculated as Al2O3) to pseudoboehmite (calculated as Al2O3) is 0.14;

[0090] (3) The molecular sieve slurry and the matrix slurry are thoroughly mixed, the remaining aluminum sol is added, and the mixture is continued to be slurry for 30 minutes. After homogenization, the resulting mixed slurry is spray-dried at 400°C and then calcined at 500°C for 1 hour to obtain catalyst A.

[0091] Preparation of catalyst B:

[0092] The preparation method for catalyst A is followed, except that...

[0093] In step (1), USY molecular sieve is used instead of ReUSY molecular sieve, and the amount of aluminum sol used accounts for 20% of the total amount of aluminum sol on a dry basis.

[0094] Catalyst A and catalyst B were mixed at a mass ratio of 17:3 to obtain a combined catalytic cracking catalyst. The formulations of catalyst A and catalyst B are shown in Table 2, and the performance parameters of catalyst A and catalyst B and the effect of the combined catalyst are shown in Table 3.

[0095] Example 2

[0096] Preparation of catalyst A:

[0097] The preparation method of catalyst A in Example 1 was followed, except that...

[0098] In step (1), USY molecular sieve is used instead of ReUSY molecular sieve, and the amount of aluminum sol used accounts for 20% of the total amount of aluminum sol on a dry basis.

[0099] Preparation of catalyst B:

[0100] The preparation method of catalyst A in Example 1 was followed, except that...

[0101] In step (1), USY molecular sieve is used instead of ReUSY molecular sieve, and the amount of aluminum sol used accounts for 20% of the total amount of aluminum sol on a dry basis.

[0102] Catalyst A and catalyst B were mixed at a mass ratio of 1:1 to obtain a combined catalytic cracking catalyst. The formulations of catalyst A and catalyst B are shown in Table 2, and the performance parameters of catalyst A and catalyst B and the effect of the combined catalyst are shown in Table 3.

[0103] Example 3

[0104] Preparation of catalyst A:

[0105] The preparation method of catalyst A in Example 1 was followed, except that...

[0106] In step (1), ReUSY-2 molecular sieve is used instead of ReUSY-1 molecular sieve, and the amount of aluminum sol used accounts for 50% of the total amount of aluminum sol on a dry basis.

[0107] Preparation of catalyst B:

[0108] The preparation method of catalyst A in Example 1 was followed, except that...

[0109] In step (1), USY molecular sieve is used instead of ReUSY molecular sieve, and the amount of aluminum sol used accounts for 20% of the total amount of aluminum sol on a dry basis.

[0110] Catalyst A and catalyst B were mixed at a mass ratio of 17:3 to obtain a combined catalytic cracking catalyst. The formulations of catalyst A and catalyst B are shown in Table 2, and the performance parameters of catalyst A and catalyst B and the effect of the combined catalyst are shown in Table 3.

[0111] Example 4

[0112] Preparation of catalyst A:

[0113] The preparation method of catalyst A in Example 1 was followed.

[0114] Preparation of catalyst B:

[0115] The preparation method of catalyst A in Example 1 was followed, except that...

[0116] In step (1), USY molecular sieve is used instead of ReUSY molecular sieve, and the amount of aluminum sol used accounts for 20% of the total amount of aluminum sol on a dry basis.

[0117] Catalyst A and catalyst B were mixed at a mass ratio of 9:1 to obtain a combined catalytic cracking catalyst. The formulations of catalyst A and catalyst B are shown in Table 2, and the performance parameters of catalyst A and catalyst B and the effect of the combined catalyst are shown in Table 3.

[0118] Example 5

[0119] Preparation of catalyst A:

[0120] The preparation method of catalyst A in Example 1 was followed, except that...

[0121] In step (1), the amount of aluminum sol used accounts for 50% of the total amount of aluminum sol on a dry basis.

[0122] Preparation of catalyst B:

[0123] The preparation method of catalyst A in Example 1 was followed, except that...

[0124] In step (1), USY molecular sieve is used instead of ReUSY molecular sieve.

[0125] Catalyst A and catalyst B were mixed at a mass ratio of 9:1 to obtain a combined catalytic cracking catalyst. The formulations of catalyst A and catalyst B are shown in Table 2, and the performance parameters of catalyst A and catalyst B and the effect of the combined catalyst are shown in Table 3.

[0126] Example 6

[0127] Preparation of catalyst A:

[0128] The preparation method of catalyst A in Example 1 was followed.

[0129] Preparation of catalyst B:

[0130] The preparation method of catalyst A in Example 1 was followed.

[0131] Catalyst A and catalyst B were mixed at a mass ratio of 10:1 to obtain a combined catalytic cracking catalyst. The formulations of catalyst A and catalyst B are shown in Table 2, and the performance parameters of catalyst A and catalyst B and the effect of the combined catalyst are shown in Table 3.

[0132] Comparative Example 1

[0133] Catalyst A was prepared according to the method in Example 1, except that catalyst B was not added to the combined catalyst.

[0134] The formulation of catalyst A is shown in Table 2, and the performance parameters of catalyst A and the effect of the combined catalyst are shown in Table 3.

[0135] Comparative Example 2

[0136] Preparation of catalyst A:

[0137] The preparation method of catalyst A in Example 1 was followed, except that...

[0138] In step (1), USY molecular sieve is used instead of ReUSY molecular sieve, and the amount of aluminum sol used is 10% of the total amount of aluminum sol on a dry basis.

[0139] Preparation of catalyst B:

[0140] The preparation method of catalyst A in Example 1 was followed, except that...

[0141] In step (1), USY molecular sieve is used instead of ReUSY molecular sieve, and the amount of aluminum sol used accounts for 20% of the total amount of aluminum sol on a dry basis.

[0142] Catalyst A and catalyst B were mixed at a mass ratio of 1:1 to obtain a combined catalytic cracking catalyst. The formulations of catalyst A and catalyst B are shown in Table 2, and the performance parameters of catalyst A and catalyst B and the effect of the combined catalyst are shown in Table 3.

[0143] Comparative Example 3

[0144] Preparation of catalyst A:

[0145] The preparation method of catalyst A in Example 1 was followed.

[0146] Preparation of catalyst B:

[0147] The preparation method of catalyst A in Example 1 was followed, except that...

[0148] In step (1), the amount of aluminum sol used is 5% of the total amount of aluminum sol on a dry basis.

[0149] Catalyst A and catalyst B were mixed at a mass ratio of 17:3 to obtain a combined catalytic cracking catalyst. The formulations of catalyst A and catalyst B are shown in Table 2, and the performance parameters of catalyst A and catalyst B and the effect of the combined catalyst are shown in Table 3.

[0150] Comparative Example 4

[0151] Preparation of catalyst A:

[0152] The preparation method of catalyst A in Example 1 was followed.

[0153] Preparation of catalyst B:

[0154] The preparation method of catalyst A in Example 1 was followed, except that...

[0155] In step (1), no Y molecular sieve is added, and the amount of silica sol used is 100% of the total amount of silica sol on a dry basis;

[0156] In step (3), without adding silica sol, add 75% phosphoric acid to the obtained mixed slurry to adjust the pH value to 3.

[0157] Catalyst A and catalyst B were mixed at a mass ratio of 17:3 to obtain a combined catalytic cracking catalyst. The formulations of catalyst A and catalyst B are shown in Table 2, and the performance parameters of catalyst A and catalyst B and the effect of the combined catalyst are shown in Table 3.

[0158] Table 1 Properties of the feedstock oil

[0159]

[0160] Table 2 Catalyst Formulation

[0161]

[0162] The content of each component in Table 2 is the weight percentage on a dry basis.

[0163] Table 3. Performance parameters of catalysts and effects of combined catalysts

[0164]

[0165] Table 3 (continued)

[0166]

[0167] The catalytic cracking combination catalyst provided by this invention has a low wear index and exhibits high low-carbon olefin yield and high propylene selectivity in heavy oil catalytic cracking, without increasing the yield of heavy oil and diesel.

[0168] The results from Examples 1 to 5 show that by controlling the bulk density of catalyst A, the bulk density of catalyst B, the bulk density of catalyst A and catalyst B, and the weight ratio of Y-type molecular sieves contained in catalyst A and catalyst B within the ranges defined in this invention, the resulting combined catalyst exhibits both high yield of low-carbon olefins and propylene selectivity, without increasing the yield of diesel and heavy oil, resulting in better overall catalytic cracking performance. Combining the results from Examples 1 and 6, it can be seen that Example 6, because it did not use the weight ratio of catalyst A and catalyst B defined in this invention, resulted in a slight decrease in the yield of low-carbon olefins and propylene selectivity of the combined catalyst.

[0169] Based on Examples 1 and 1, it can be seen that, since Comparative Example 1 uses only a single catalyst A, the yield of low-carbon olefins and the selectivity of propylene obtained by the combined catalyst are lower than those of Example 1. Based on Examples 1, 2, and 3, it can be seen that, in Comparative Examples 2 and 3, the weight ratio of Y-type molecular sieves contained in catalyst A and catalyst B is not within the range specified by this invention, resulting in a lower yield of low-carbon olefins and poorer selectivity of propylene obtained by the combined catalyst. Based on Examples 1 and 4, it can be seen that, in Comparative Example 4, catalyst B was not prepared using the method provided by this invention, but using a conventional co-catalyst preparation method. The resulting catalyst B has a large deviation in wear index from catalyst A, leading to greater wear and consumption between the two catalysts, and a lower yield of low-carbon olefins obtained by the combined catalyst.

[0170] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A catalytic cracking composite catalyst, characterized in that, The combined catalyst comprises catalyst A and catalyst B, and catalyst A and catalyst B are mixed to obtain the combined catalyst; wherein, the bulk density of catalyst A is 0.7-0.79 g / cm³. 3 The bulk density of catalyst B is 0.81-0.87 g / cm³. 3 The bulk density ratio of catalyst A to catalyst B is 0.88-0.

95. The Y-type molecular sieve contained in catalyst A and catalyst B are in a dry weight ratio of 2-4:

1.

2. The combined catalyst according to claim 1, wherein, The weight ratio of catalyst A to catalyst B is 1-9:1; And / or, the pore volume of catalyst A is 0.31-0.37 cm³. 3 / g; And / or, the pore volume of the catalyst B is 0.29-0.31 cm³. 3 / g.

3. The combined catalyst according to claim 2, wherein, The weight ratio of catalyst A to catalyst B is 7-26:

3.

4. The combined catalyst according to any one of claims 1-3, wherein, Based on the dry weight of catalyst A, catalyst A contains: 10-25% by weight of Y-type molecular sieve, 15-35% by weight of modified ZSM-5, 15-27% by weight of binder and 30-50% by weight of clay.

5. The combined catalyst according to any one of claims 1-3, wherein, Based on the dry weight of catalyst B, catalyst B contains: 3-8% by weight of Y-type molecular sieve, 25-40% by weight of modified ZSM-5, 15-27% by weight of binder and 30-50% by weight of clay.

6. A method for preparing a catalytic cracking composite catalyst, characterized in that, The method includes: (1) Y-type molecular sieve, modified ZSM-5, part of the first binder and water are pulped to obtain pre-bonded molecular sieve slurry; (2) Mix clay, second binder, inorganic acid and water thoroughly to form a matrix slurry, and then allow it to mature; (3) The pre-bonded molecular sieve slurry is thoroughly mixed with the matured matrix slurry, and then the remaining first binder is added and mixed evenly to obtain the catalyst slurry; (4) The catalyst slurry is homogenized, spray-dried and calcined to obtain catalyst A or catalyst B; (5) Mix catalyst A and catalyst B to obtain the combined catalyst; The bulk density of catalyst A is 0.7-0.79 g / cm³. 3 The bulk density of catalyst B is 0.81-0.87 g / cm³. 3 The bulk density ratio of catalyst A to catalyst B is 0.88-0.

95. The Y-type molecular sieve contained in catalyst A and catalyst B are in a dry weight ratio of 2-4:

1.

7. The method according to claim 6, wherein, In the preparation method of catalyst A, based on the dry weight of the pre-bonded molecular sieve slurry, the weight ratio of Y-type molecular sieve and modified ZSM-5 in the pre-bonded molecular sieve slurry is (2-5):(3-7) on a dry basis. And / or, in the preparation method of catalyst B, based on the dry weight of the pre-bonded molecular sieve slurry, the weight ratio of Y-type molecular sieve and modified ZSM-5 in the pre-bonded molecular sieve slurry is (3-8):(25-40) on a dry basis. And / or, the Y-type molecular sieve is selected from ReUSY type and / or USY type molecular sieve; And / or, the silicon-to-aluminum ratio (SiO2 / Al2O3) of the Y-type molecular sieve is 3.1-5; And / or, the modifying elements contained in the modified ZSM-5 are selected from at least one of phosphorus, alkaline earth metal elements and transition metal elements; And / or, the content of the modifying elements in the modified ZSM-5, calculated as oxides, is 1.5-5 wt%.

8. The method according to claim 7, wherein, The modifying elements contained in the modified ZSM-5 are selected from at least two of phosphorus, alkaline earth metals and transition metals. And / or, the Re2O3 content in the ReUSY type molecular sieve is ≤3wt%; And / or, the alkaline earth metal element is Mg; And / or, the transition metal element is selected from at least one of Fe, Co, Ni, Zn and Cu.

9. The method according to any one of claims 6-8, wherein, The first binder is selected from at least one of silica sol, alumina sol and boehmite; And / or, the second binder is selected from at least one of silica sol, alumina sol and boehmite; And / or, on a dry basis, the weight ratio of the first adhesive to the second adhesive is (7-12):(8-15); And / or, the first adhesive is a portion of the first adhesive and the remainder of the first adhesive; And / or, the clay is selected from at least one of kaolin, halloysite and bentonite; And / or, on a dry basis, the weight ratio of the clay to the second binder is (30-50):(8-15); And / or, the inorganic acid is selected from at least one of hydrochloric acid, nitric acid, and sulfuric acid; And / or, with H + The molar ratio of the inorganic acid to the second binder on a dry basis is 0.1-0.5:

1.

10. The method according to claim 9, wherein, The first adhesive is silica sol and / or aluminum sol; And / or, the second adhesive is boehmite; And / or, on a dry basis, the weight ratio of the portion of the first adhesive to the remaining first adhesive is 1:1-9; And / or, the clay is kaolin.

11. The method according to any one of claims 6-8, wherein, In step (4), the spray drying temperature is 370-450℃ and the time is 0.05-10min; the calcination temperature is 400-550℃ and the time is 0.5-2h.

12. The application of the catalytic cracking combined catalyst according to any one of claims 1-5 or the catalytic cracking combined catalyst prepared by the method according to any one of claims 6-11 in heavy oil cracking.

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