Vanadium poisoning resistant catalytic cracking catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalytic cracking, and relates to a vanadium poisoning resistant catalytic cracking catalyst and a preparation method and application thereof, the vanadium poisoning resistant catalytic cracking catalyst contains a rare earth metal modified molecular sieve and a matrix material, and the matrix material is composed of an alkaline earth metal oxide and a silicon-aluminum material. The vanadium poisoning-resistant catalytic cracking catalyst disclosed by the invention has a good heavy metal vanadium pollution-resistant effect, is high in raw oil conversion rate in a high-vanadium raw oil catalytic cracking process, and has higher low-carbon olefin yield.

Description

Technical Field

[0001] This invention relates to a vanadium-resistant catalytic cracking catalyst, its preparation method, and its application. Background Technology

[0002] As domestic refined oil consumption enters a stable period, the supply-side structure of the refining industry faces adjustment, and "oil conversion" has become an important direction for adjusting the product structure of refining. Some imported crude oils have a high vanadium content. In catalytic cracking units, after blending a certain proportion of high-vanadium oil residue, the yield of dienes decreases significantly, the yield of coke increases, and the consumption of catalysts increases significantly.

[0003] Existing technologies for vanadium-resistant catalysts generally involve adding a vanadium-resistant matrix during the molding process, designing a metal coating on the support, or preparing vanadium-resistant additives. All of these methods exhibit some resistance to heavy metals. CN1223403C discloses a novel matrix-type heavy metal-resistant FCC catalyst and its preparation method. This catalyst contains 20-80 m% clay, 5-40 m% binder, 1-25 m% metal trapping components (such as rare earth oxalate), 0-30 m% other oxides (such as activated alumina), and 5-40 m% of octahedral zeolite, ZSM-5 zeolite, β-zeolite, or mixtures thereof, with a cell constant of 2.432-2.472 nm. This catalyst exhibits excellent heavy metal resistance and is suitable as a catalyst for cracking heavy oils with high V and other content.

[0004] However, existing vanadium-resistant technologies mainly revolve around catalytic cracking, while catalytic cracking processes are more demanding than catalytic cracking, requiring the production of more ethylene and propylene. Existing vanadium-resistant technologies cannot effectively solve the problem of vanadium poisoning in catalytic cracking catalysts, and currently there are no catalysts with good vanadium resistance developed for catalytic cracking. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a vanadium-resistant catalytic cracking catalyst, its preparation method and application. The vanadium-resistant catalytic cracking catalyst has good resistance to heavy metal vanadium pollution and achieves high ethylene and propylene yields when used in the catalytic cracking process of high vanadium feedstock oil.

[0006] Therefore, this application provides a vanadium poisoning catalytic cracking catalyst, which contains a rare earth metal modified molecular sieve and a matrix material. The matrix material includes an alkaline earth metal oxide component and a silicon-aluminum material component. The rare earth elements of the rare earth modified molecular sieve are enriched and distributed on the outer surface of the molecular sieve, and the alkaline earth metals in the matrix material are enriched and distributed on the outer surface of the catalyst.

[0007] The vanadium poisoning catalytic cracking catalyst, wherein, based on the dry weight of the catalyst, the content of the rare earth metal modified molecular sieve is preferably 20-60 wt% on a dry basis, the content of the alkaline earth metal oxide component is 0.1-5 wt% on a dry basis, and the content of the silicon-aluminum material component is 35-80 wt% on a dry basis.

[0008] The vanadium poisoning-resistant catalytic cracking catalyst, preferably, contains 0.5-8 wt% precipitated rare earth metal oxide components in the rare earth metal modified molecular sieve. According to the present invention, the rare earth in the rare earth modified molecular sieve may include exchanged rare earth and non-exchangeable rare earth (or precipitated rare earth). In one embodiment, the exchanged rare earth in the rare earth metal modified molecular sieve is 0-3 wt% of the rare earth metal modified molecular sieve, and the precipitated rare earth content is 0.5-8 wt%, for example, 1-5 wt%. The rare earth content is calculated as RE₂O₃.

[0009] According to the vanadium poisoning-resistant catalytic cracking catalyst of the present invention, in one embodiment, the rare earth element enrichment distribution is as follows: in the rare earth metal modified molecular sieve, the mass ratio of the rare earth element content on the outer surface of the rare earth metal modified molecular sieve to the total precipitated rare earth element content (both referring to percentage content) (total precipitated rare earth element content or bulk precipitated rare earth element content) is 1.3 or higher, for example, 1.3-2.5 or 1.4-2.1. The surface rare earth element content is measured by XPS method and is the concentration of rare earth metal elements in the region within 5 nm of the molecular sieve particle surface; the total precipitated rare earth element content is the content or concentration of precipitated rare earth metal elements (e.g., rare earth introduced by leaching) in the entire rare earth modified molecular sieve, which can be measured by chemical method or XRF method.

[0010] According to the vanadium poisoning catalytic cracking catalyst of the present invention, the rare earth metal elements in the rare earth metal modified molecular sieve preferably include one or more of cerium, lanthanum or yttrium.

[0011] According to the vanadium poisoning-resistant catalytic cracking catalyst of the present invention, preferably, the molecular sieve in the rare earth metal modified molecular sieve includes Y-type molecular sieve and ZSM-5 molecular sieve. The weight ratio of Y-type molecular sieve to ZSM-5 molecular sieve can be 1-3:1.

[0012] According to the vanadium poisoning-resistant catalytic cracking catalyst of the present invention, the molecular sieve can be a commonly used molecular sieve in catalytic cracking catalysts. For example, the Y-type molecular sieve can be an ultrastable Y-type molecular sieve, a hydrogen-form ultrastable Y-type molecular sieve, and / or an ultrastable Y-type molecular sieve containing exchangeable rare earth elements. The ultrastable Y-type molecular sieve can be one or more of DASY molecular sieve (hydrothermal ultrastable Y-type molecular sieve) and USY molecular sieve (gas-phase ultrastable Y-type molecular sieve); the ZSM-5 molecular sieve can be a hydrogen-form ZSM-5 molecular sieve and / or a phosphorus-containing ZSM-5 molecular sieve (phosphorus-modified ZSM-5 molecular sieve).

[0013] According to the vanadium poisoning catalytic cracking catalyst of the present invention, preferably, the alkaline earth metal oxide in the matrix material includes one or more of magnesium oxide, barium oxide, or strontium oxide.

[0014] The content of alkaline earth metal oxides in the catalyst is preferably 0.5-5% by weight, for example 2-5% by weight. The alkaline earth metal oxides are, for example, alkaline earth metal oxides introduced by a rinsing method.

[0015] In one embodiment, the alkaline earth metal enrichment distribution is as follows: the ratio of alkaline earth metal element content on the outer surface of the catalyst to the total alkaline earth metal element content in the catalyst is preferably 1.1-2.1:1, for example, 1.5-1.9:1; the content refers to mass percentage. The alkaline earth metal content on the outer surface of the catalyst is obtained by measuring the concentration of alkaline earth metal elements in the region within 5 nm of the outer surface of the catalyst particles using XPS. The total alkaline earth metal element content of the catalyst is obtained by chemical methods or XRF methods. The total alkaline earth metal elements are, for example, alkaline earth metal elements introduced by leaching.

[0016] According to the vanadium poisoning catalytic cracking catalyst of the present invention, the matrix material contains both silicon and aluminum elements in its silicon-aluminum component, and may include, for example, one, two, or more of kaolin, alumina support, and silica sol, such as two or three of these elements. The alumina support is preferably one or more of alumina sol, acidified boehmite, hydrated alumina, and activated alumina; the silica sol may include one or more of neutral silica sol, acidic silica sol, or alkaline silica sol.

[0017] In one embodiment, the vanadium-resistant catalytic cracking catalyst comprises 25-50 wt% molecular sieve, 5-30 wt% boehmite, 3-20 wt% alumina sol, 10-35 wt% silica sol, 10-40 wt% kaolin, and 0.5-5 wt% alkaline earth metal oxides. The molecular sieve is either a Y-type molecular sieve or a ZSM-5 molecular sieve, wherein the weight ratio of the Y-type molecular sieve to the ZSM-5 molecular sieve is 1-3:1.

[0018] The present invention also provides a method for preparing the vanadium poisoning-resistant catalytic cracking catalyst, comprising the following steps:

[0019] S1. Molecular sieves are mixed with water to obtain slurry A, which is then filtered to obtain filter cake A; the filtration is, for example, vacuum filtration or suction filtration.

[0020] S2. Filter cake A is rinsed (referred to as first rinsing) with an alkaline solution (referred to as first alkaline solution) and filtered to obtain filter cake B; the filtration is, for example, vacuum filtration or suction filtration.

[0021] S3. The filter cake B is washed (referred to as the second washing) and filtered using a rare earth metal salt solution A, then dried and calcined to obtain a rare earth modified molecular sieve; the filtration is, for example, vacuum filtration or suction filtration.

[0022] S4. Rare earth modified molecular sieve, silicon-aluminum material and water are mixed to obtain slurry B, and particles A are obtained by spray drying.

[0023] S5. Mix particle A with ammonium salt and water for ammonium exchange, or calcine particle A for the first time to obtain particle B. Then mix particle B with ammonium salt and water for ammonium exchange, dry, and calcine for the second time to obtain particle C.

[0024] S6. Mix particles C with water to obtain slurry C, and filter to obtain filter cake C; the filtration is, for example, vacuum filtration or suction filtration.

[0025] S7. The filter cake C is rinsed with an alkaline solution (referred to as the second alkaline solution) (referred to as the third rinsing) and filtered to obtain filter cake D; the filtration is, for example, vacuum filtration or suction filtration.

[0026] S8. The filter cake D is washed with alkaline earth metal salt solution B (referred to as the fourth washing), filtered, dried, and calcined to obtain the catalytic cracking catalyst. The filtration is, for example, vacuum filtration or suction filtration.

[0027] In one embodiment of the method for preparing the vanadium poisoning catalytic cracking catalyst, in step S1, the molecular sieve is a Y-type molecular sieve and a ZSM-5 molecular sieve, wherein the mass ratio of the Y-type molecular sieve to the ZSM-5 molecular sieve is, for example, 1 to 3:1, preferably 1:1 to 2:1.

[0028] The method for preparing the vanadium poisoning-resistant catalytic cracking catalyst, wherein in step S2, the alkaline solution (referred to as the first alkaline solution) is an ammonia solution and / or an ammonium carbonate solution, and the pH value of the alkaline solution is 8-10, for example 8-9 or 9-10. The weight ratio of the alkaline solution (first alkaline solution) to the filter cake A on a dry basis is 0.5:1-3:1.

[0029] In the method for preparing the vanadium poisoning-resistant catalytic cracking catalyst, in step S3, the concentration of rare earth salts in the rare earth salt solution A, calculated as RE2O3, is 10-30 wt%. The rare earth salts are, for example, rare earth chloride salts or rare earth nitrates.

[0030] Optionally, the filter cake B is leached with a rare earth metal salt solution A, so that the rare earth introduced into the rare earth modified molecular sieve through leaching (referred to as leached rare earth, or precipitated rare earth) is 0.5-8% by weight of the dry basis of the rare earth modified molecular sieve, calculated as RE2O3.

[0031] The method for preparing the vanadium poisoning catalytic cracking catalyst, wherein in step S3, the drying temperature is 100-150℃; the calcination temperature is 400-600℃, the calcination time is 1-6 hours, and the calcination atmosphere has no special requirements, such as an air atmosphere.

[0032] The method for preparing the vanadium poisoning-resistant catalytic cracking catalyst includes step S4, in which rare earth modified molecular sieve, silicon-aluminum material, and water are mixed to obtain slurry B, which is then spray-dried to obtain particles A. The solid content of slurry B is preferably 15-40% by weight, for example, 20-30% by weight.

[0033] In one embodiment, the silica-alumina material comprises one or more, preferably two or three, of alumina carrier materials, including kaolin, silica sol, and alumina carrier materials, preferably containing silica sol. The alumina carrier material is, for example, one or more of hydrated alumina, alumina sol, and activated alumina; the hydrated alumina is, for example, one or more of alumina trihydrate, boehmite, and boehmite, preferably boehmite, and more preferably, the boehmite is acidified to form acidified boehmite; the activated alumina is, for example, one or more of γ-alumina, η-alumina, and κ-alumina. The acid used for acidification is, for example, hydrochloric acid, and the acid-aluminum ratio (weight ratio of hydrochloric acid at 37% by weight of HCl to boehmite (calculated as Al2O3)) in the acidified boehmite acidification process is 0.15-0.22:1.

[0034] The method for preparing the vanadium poisoning catalytic cracking catalyst, wherein in step S5, the ammonium exchange involves mixing particles B, ammonium salt, and water in a weight ratio of 1:(0.2-2):(5-18) for ammonium exchange, and the conditions for the ammonium exchange include a temperature of 50-100℃ and a time of 0.5-2 hours; the ammonium salt is selected from one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate.

[0035] The method for preparing the vanadium poisoning-resistant catalytic cracking catalyst includes the following steps: In step S5, the drying temperature is 100-150℃; the calcination temperature is 400-600℃, the time is 1-6 hours, and the atmosphere is air. The calcination can be performed once or multiple times, for example, twice, wherein the first calcination occurs before ammonium exchange, and the second calcination occurs after ammonia exchange. The conditions for the first and second calcinations can be the same or different.

[0036] The method for preparing the vanadium poisoning-resistant catalytic cracking catalyst, wherein in step S7, the alkaline solution (second alkaline solution) is an ammonia solution and / or an ammonium carbonate solution, and the pH value of the alkaline solution is 8-10, for example 8-9 or 9-10. The weight ratio of the alkaline solution (second alkaline solution) to the filter cake C on a dry basis is 0.5:1-3:1.

[0037] In the method for preparing the vanadium poisoning catalytic cracking catalyst, in step S8, the concentration of alkaline earth metal salt in the alkaline earth salt solution A is 15-35 wt%.

[0038] Optionally, in step S8, the filter cake D is leached with an alkaline earth metal salt solution B, such that the alkaline earth metal introduced by the leaching in the obtained catalytic cracking catalyst (referred to as the leached alkaline earth metal) is 0.5-5% by weight (based on oxides) of the dry basis of the catalytic cracking catalyst.

[0039] In the method for preparing the vanadium poisoning catalytic cracking catalyst, in step S8, in one embodiment, the drying temperature is 100-150℃; the calcination temperature is 400-600℃, the calcination time is 1-6 hours, and the calcination atmosphere is air.

[0040] The present invention further provides a vanadium-resistant catalytic cracking catalyst prepared by the method described herein.

[0041] The present invention further provides the application of the vanadium poisoning-resistant catalytic cracking catalyst in the catalytic cracking of high vanadium feedstock oil.

[0042] The reaction conditions for the catalytic cracking include: a reaction temperature of 560-620℃, for example 570℃, 580℃, 590℃, or 600℃; an agent-to-oil ratio of 4-30, for example 6-10 by weight; and a reaction time of, for example 0.5-6 seconds, for example 1-3 seconds.

[0043] Compared with the prior art, the catalytic cracking catalyst provided by the present invention has one or more of the following beneficial effects, preferably all of them:

[0044] 1. The vanadium-resistant catalytic cracking catalyst of the present invention uses rare earth and alkaline earth metals on the outer surface of different catalytic materials to better suppress the erosion effect of vanadium on the catalyst matrix and molecular sieve, better protect the active center of the molecular sieve, improve the conversion capacity of heavy oil catalytic cracking, and increase the yield of ethylene and propylene.

[0045] 2. The vanadium poisoning-resistant catalytic cracking catalyst of the present invention adopts the method of precipitation of rare earth elements on the outer surface of molecular sieve. The content of rare earth elements precipitated on the outer surface of the molecule is relatively high. In preferred cases, it can form a stable compound with vanadium on the outer surface, which greatly inhibits the erosion effect of vanadium on molecular sieve, protects the active center of molecular sieve, and improves the conversion capacity of heavy oil and the yield of ethylene and propylene.

[0046] 3. In the preferred embodiment, the matrix material of the vanadium poisoning catalytic cracking catalyst of the present invention uses silica sol, which can increase a portion of silicon dioxide in the matrix, weaken the corrosive effect of vanadium acid on the catalyst, thereby playing an anti-vanadium role and effectively inhibiting the corrosion of the catalyst by vanadium acid.

[0047] The method for preparing vanadium-resistant catalysts provided by this invention can obtain catalysts containing rare earth elements on the outer surface of molecular sieves and alkaline earth metals on the outer surface of catalyst particles. Furthermore, the prepared catalysts can reduce the formation of large-particle rare earth oxides and alkaline earth metal oxides, resulting in more metal oxides on the surface, which is beneficial for forming stable compounds with vanadium on the outer surface. The prepared catalysts have better yields of propylene and ethylene from heavy oil cracking and improve the yield of liquefied petroleum gas.

[0048] The catalytic cracking catalyst provided by this invention is particularly suitable for the catalytic cracking of vanadium-containing heavy oil to produce low-carbon olefins. Detailed Implementation

[0049] Unless otherwise specified, all raw materials used in the following examples and comparative examples were commercially available, wherein:

[0050] Y-type molecular sieve, DASY2.0 produced by Qilu Branch of Sinopec Catalyst Co., Ltd., with rare earth content of 2% by weight (RE2O3).

[0051] ZSM-5 molecular sieve, produced by Sinopec Catalyst Co., Ltd. Qilu Branch as RMPZ-3, has a silicon-to-aluminum ratio (SiO2 / Al2O3 molar ratio) of 25.

[0052] Aluminum sol, a product of Sinopec Catalysts Qilu Branch, with an Al2O3 content of 22% by weight.

[0053] Silica sol, SiO2 content 16% by weight, product of Beijing Chemical Plant, pH value 2.5.

[0054] Boehmite, a product of Shandong Aluminum Company, with an alumina content of 65% by weight.

[0055] Kaolin, solid content 75% by weight, industrial product of China Kaolin Company.

[0056] Example 1:

[0057] 1) Mix 38g of molecular sieve (on a dry basis, the same below) with 200ml of water, wherein the mass ratio of Y-type molecular sieve to ZSM-5 type molecular sieve is 2:1, and filter the resulting slurry to obtain filter cake.

[0058] 2) Prepare 35g of an alkaline solution with ammonia water to a pH of 9 and rinse the filter cake while vacuum filtering until it is dry;

[0059] 3) Use 4.33g of cerium chloride to prepare a rare earth metal salt solution with a concentration of 15wt% (calculated as CeO2) to wash the filter cake, dry it at 120℃ for 8h, and calcine it at 550℃ for 4h to obtain rare earth modified molecular sieve.

[0060] 4) Rare earth modified molecular sieve, boehmite, alumina sol, silica sol, and kaolin are mixed with water in a weight ratio of 40:20:10:10:20, and hydrochloric acid is added to form a slurry with a solid content of 22% by weight. In the above ratio, the modified molecular sieve and kaolin are calculated on a dry basis, the boehmite and alumina sol are calculated on alumina, and the silica sol is calculated on silica. The ratio of hydrochloric acid to boehmite is 0.2 by mass, where the hydrochloric acid is calculated as HCl concentration 37% by weight, and the boehmite is calculated as Al2O3. The slurry is spray-dried to obtain a shaped solid, and then calcined at 550℃ for 2 hours.

[0061] 5) Solid molding: Ammonium chloride and deionized water were mixed evenly at a mass ratio of 1:0.5:10, subjected to a second ammonium exchange, filtered, washed, dried, and calcined at 550℃ for 2 hours to obtain granules C;

[0062] 6) Mix 30g of granules C with 500ml of water, and filter the resulting slurry to obtain filter cake C;

[0063] 7) Prepare 40g of an alkaline solution with ammonia water to a pH of 9, and use it to filter the filter cake while rinsing it to obtain filter cake D;

[0064] 8) The filter cake D was washed with a 15wt% alkaline earth metal salt solution prepared with 3.73g of magnesium chloride, dried at 120℃ for 8h, and calcined at 550℃ for 4h to obtain the catalytic cracking catalyst.

[0065] Example 2:

[0066] 1) Mix 38.8g of molecular sieve with 200ml of water, wherein the mass ratio of Y-type molecular sieve to ZSM-5 type molecular sieve is 1:1, and filter the resulting slurry to obtain filter cake;

[0067] 2) Prepare 35g of an alkaline solution with ammonia water to a pH of 9 and rinse the filter cake while vacuum filtering until it is dry;

[0068] 3) Use 2.60g of cerium chloride to prepare a rare earth metal salt solution with a concentration of 15wt% (calculated as CeO2) to wash the filter cake, dry it at 120℃ for 8h, and calcine it at 550℃ for 4h to obtain rare earth modified molecular sieve.

[0069] 4) Rare earth modified molecular sieve, boehmite, alumina sol, silica sol, and kaolin were mixed with water in a weight ratio of 40:20:10:10:20, and hydrochloric acid was added to form a slurry with a solid content of 22% by weight. The modified molecular sieve and kaolin were calculated on a dry basis, the boehmite and alumina sol were calculated on alumina, and the silica sol was calculated on silica. The ratio of hydrochloric acid to boehmite was 0.2 by mass, where the hydrochloric acid was calculated as HCl concentration 37% by weight, and the boehmite was calculated as Al2O3. The slurry was spray-dried to obtain a shaped solid, and then calcined at 550℃ for 2 hours.

[0070] 5) Solid molding: Ammonium chloride and deionized water were mixed evenly at a mass ratio of 1:0.5:10, subjected to a second ammonium exchange, filtered, washed, dried, and calcined at 550℃ for 2 hours to obtain granules C;

[0071] 6) Mix 30g of granules C with 500ml of water, and filter the resulting slurry to obtain filter cake C;

[0072] 7) Prepare 40g of an alkaline solution with ammonia water to a pH of 9, and use it to filter the filter cake while rinsing it to obtain filter cake D;

[0073] 8) The filter cake D was washed with a 15wt% alkaline earth metal salt solution prepared with 3.73g of magnesium chloride, dried at 120℃ for 8h, and calcined at 550℃ for 4h to obtain the catalytic cracking catalyst.

[0074] Example 3:

[0075] 1) Mix 39.6g of molecular sieve with 200ml of water, wherein the mass ratio of Y-type molecular sieve to ZSM-5 type molecular sieve is 2:1, and filter the resulting slurry to obtain filter cake;

[0076] 2) Prepare 35g of an alkaline solution with ammonia water to a pH of 9 and rinse the filter cake while vacuum filtering until it is dry;

[0077] 3) Use 0.87g of cerium chloride to prepare a rare earth metal salt solution with a cerium oxide (calculated as CeO2) concentration of 15wt% to wash the filter cake, dry it at 120℃ for 8h, and calcine it at 550℃ for 4h to obtain rare earth modified molecular sieve.

[0078] 4) Rare earth modified molecular sieve, boehmite, alumina sol, silica sol, and kaolin were mixed with water in a weight ratio of 40:20:10:10:20, and hydrochloric acid was added to form a slurry with a solid content of 22% by weight. The modified molecular sieve and kaolin were calculated on a dry basis, the boehmite and alumina sol were calculated on alumina, and the silica sol was calculated on silica. The ratio of hydrochloric acid to boehmite was 0.2 by mass, where the hydrochloric acid was calculated as 37% HCl and the boehmite was calculated as Al2O3. The slurry was spray-dried to obtain a shaped solid, and then calcined at 550℃ for 2 hours.

[0079] 5) Solid molding: Ammonium chloride and deionized water were mixed evenly at a mass ratio of 1:0.5:10, subjected to a second ammonium exchange, filtered, washed, dried, and calcined at 550℃ for 2 hours to obtain granules C;

[0080] 6) Mix 30g of granules C with 500ml of water, and filter the resulting slurry to obtain filter cake C;

[0081] 7) Prepare 40g of an alkaline solution with ammonia water to a pH of 9, and use it to filter the filter cake while rinsing it to obtain filter cake D;

[0082] 8) The filter cake D was washed with a 15wt% alkaline earth metal salt solution prepared with 3.73g of magnesium chloride, dried at 120℃ for 8h, and calcined at 550℃ for 4h to obtain the catalytic cracking catalyst.

[0083] Example 4:

[0084] 1) Mix 39.6g of molecular sieve with 200ml of water, wherein the mass ratio of Y-type molecular sieve to ZSM-5 type molecular sieve is 1:1, and filter the resulting slurry to obtain filter cake.

[0085] 2) Prepare 100ml of an alkaline solution with ammonia water to a pH of 8, and rinse the filter cake while filtering it through a vacuum tube.

[0086] 3) The filter cake was washed with a rare earth metal salt solution with a cerium oxide concentration of 15wt% prepared by 0.87g cerium chloride, dried at 120℃ for 8h, and calcined at 550℃ for 4h to obtain rare earth modified molecular sieve.

[0087] 4) Rare earth modified molecular sieve, boehmite, alumina sol, silica sol, kaolin, water, and hydrochloric acid are mixed and pulped to form a slurry. The weight ratio of rare earth modified molecular sieve (dry basis), boehmite (alumina basis), alumina sol (alumina basis), silica sol (silicon oxide basis), and kaolin (dry basis) is 40:20:10:10:20; the weight ratio of hydrochloric acid to boehmite is 0.2, where hydrochloric acid is calculated as HCl concentration 37% by weight, and boehmite is calculated as Al2O3. The slurry is then spray-dried to prepare a shaped solid.

[0088] 5) Solid molding: Ammonium chloride and deionized water are mixed evenly at a mass ratio of 1:0.5:10, ammonium exchange is performed, followed by filtration, washing, drying, and calcination at 550℃ for 2 hours to obtain solid particles;

[0089] 6) Mix 30g of the solid particles obtained in step 5) with 500ml of water to obtain a slurry, and filter it to obtain a filter cake;

[0090] 7) Prepare 200ml of an alkaline solution with ammonia water to a pH of 8, and use it to filter and wash the filter cake while vacuum filtering to obtain the filter cake;

[0091] 8) The filter cake was washed with a 15wt% alkaline earth metal salt solution prepared with 1.45g magnesium chloride, dried at 120℃ for 8h, and calcined at 550℃ for 4h to obtain the catalytic cracking catalyst.

[0092] Comparative Example 1

[0093] 1) The weight ratio of Y-type molecular sieve (dry basis), ZSM-5 type molecular sieve (dry basis), boehmite (Al2O3), alumina sol (Al2O3), silica sol (SiO2), and kaolin is 20:20:20:10:10:20. The above materials are mixed with water and hydrochloric acid to prepare a slurry with a solid content of 22% by weight. The ratio of hydrochloric acid to boehmite is 0.2, where the hydrochloric acid is calculated as HCl concentration of 37% by weight, and the boehmite is calculated as Al2O3. The slurry is then spray-dried to prepare a molding.

[0094] 2) Solid molding: Ammonium chloride and deionized water were mixed evenly at a mass ratio of 1:0.5:10, subjected to ammonium exchange, filtered, washed, dried, and calcined at 550℃ for 2 hours to obtain the catalytic cracking catalyst.

[0095] Comparative Example 2

[0096] The catalyst was prepared according to the method in Example 4, except that in the preparation of the modified molecular sieve, the rare earth salt solution was first mixed with the molecular sieve, and then the ammonia solution was added to precipitate the sieve. The catalyst was then prepared according to the methods in steps 4-8.

[0097] Comparative Example 3

[0098] The catalyst was prepared according to the method of Comparative Example 2, except that in step 6, the particles obtained in step (5) were mixed with an alkaline earth metal salt solution and then ammonia was added to precipitate them.

[0099] Comparative Example 4

[0100] Unlike Example 4, in step 1, the mixture was not first mixed with water, but directly mixed with the alkaline solution. In step 8), the mixture was not first mixed with water, but directly mixed with the alkaline solution.

[0101] Comparative Example 5

[0102] The method is the same as in Comparative Example 1, except that the rare earth salt and alkaline earth metal salt are added during the pulping process.

[0103] The finished catalytic cracking catalyst particles, as well as the catalysts prepared in the examples and comparative examples, were subjected to cyclic fouling (with V deposition) experiments in a cyclic aging unit. The V content on the catalyst mixture after cyclic fouling is shown in Tables 3 to 6. The steps of the cyclic fouling experiment included: introducing heavy metal V into the catalyst mixture using the Michell impregnation method, and then loading the catalyst mixture with introduced heavy metal V into a small fixed fluidized bed, where it was treated according to the following steps in the small fixed fluidized bed unit:

[0104] (a) Heating to 600°C at a heating rate of 20°C / min under a nitrogen atmosphere;

[0105] (b) Heat to 780°C at a heating rate of 1.5°C / min, and then maintain the temperature at 780°C. During the temperature maintenance process, change the treatment atmosphere according to the following steps.

[0106] (i) Treat for 10 minutes in an atmosphere containing 40% by volume nitrogen (in which the nitrogen contains 5% by volume propylene) and 60% by volume water vapor.

[0107] (ii) Treat for 10 minutes in an atmosphere containing 40% by volume nitrogen (pure nitrogen, propylene-free) and 60% by volume water vapor.

[0108] (iii) Treat for 10 minutes in an atmosphere containing 40% by volume air (containing 4000 ppm SO2) and 60% by volume water vapor.

[0109] (iv) Treat the catalyst mixture with an atmosphere containing 40% nitrogen and 60% water vapor for 10 minutes; then repeat steps (i)-(iv) in the above order once each, and then repeat step (i) to end the cycle contamination step; then carry out the aging step: the catalyst mixture after cycle contamination is aged at 800°C in an atmosphere containing 100% water vapor for 4 hours; then examine the catalytic performance of the catalyst mixture after cycle contamination-aging on the ACE unit; wherein, the high vanadium feedstock oil (physicochemical properties are shown in Table 2) enters at the bottom of the reactor and contacts the catalyst mixture, and the specific evaluation conditions and results are shown in Table 3.

[0110] The conversion rate is calculated as follows: gasoline yield + liquefied petroleum gas yield + dry gas yield + coke yield.

[0111] Table 1

[0112]

[0113] In Table 1, the content on the outer surface refers to the metal element content within a 5 nm range from the outer surface of the particles, measured by XPS. The total rare earth element content and the total alkaline earth element content were measured by XRF.

[0114] Table 2

[0115]

[0116] Table 3

[0117]

[0118] As shown in Table 3, the catalytic cracking catalyst provided by this invention has higher yields of propylene and ethylene, higher yield of liquefied petroleum gas, and better resistance to V pollution.

Claims

1. A vanadium-poisoning-resistant catalytic cracking catalyst, comprising a rare earth metal-modified molecular sieve and a matrix material, wherein the matrix material comprises an alkaline earth metal oxide component and a silicon-aluminum material component, wherein, The rare earth elements in the rare earth modified molecular sieve are enriched and distributed on the outer surface of the rare earth modified molecular sieve. The alkaline earth metals in the vanadium poisoning catalytic cracking catalyst are enriched and distributed on the outer surface of the catalyst.

2. The vanadium poisoning-resistant catalytic cracking catalyst according to claim 1, characterized in that, Based on the dry weight of the vanadium poisoning catalytic cracking catalyst, the content of the rare earth metal modified molecular sieve in the vanadium poisoning catalytic cracking catalyst is 20-60 wt%, the content of the alkaline earth metal oxide component is 0.1-5 wt%, and the content of the silicon-aluminum material component is 35-80 wt%.

3. The vanadium poisoning-resistant catalytic cracking catalyst according to claim 1, characterized in that, The content of precipitated rare earth metal oxide components in the rare earth metal modified molecular sieve, calculated as RE2O3, accounts for 0.5-8% of the total weight of the rare earth metal modified molecular sieve.

4. The vanadium poisoning-resistant catalytic cracking catalyst according to claim 1, characterized in that, The rare earth metal elements in the rare earth metal modified molecular sieve include one or more of cerium, lanthanum, or yttrium. Optionally, the content of precipitated rare earth elements in the rare earth metal modified molecular sieve, calculated as RE2O3, is 0.5-8% by weight. Optionally, the molecular sieve in the rare earth metal modified molecular sieve includes Y-type molecular sieve and ZSM-5 type molecular sieve; Optionally, the weight ratio of the Y-type molecular sieve to the ZSM-5 molecular sieve is 1-3:

1.

5. The vanadium-resistant catalytic cracking catalyst according to any one of claims 1-4, characterized in that, In the matrix material, the alkaline earth metal oxide component includes one or more of magnesium oxide, barium oxide, or strontium oxide; the silicon-aluminum material component includes one or more of kaolin, alumina carrier, and silica sol; the alumina carrier is preferably one or more of alumina sol, acidified boehmite, hydrated alumina, and activated alumina; the silica sol includes, for example, one or more of neutral silica sol, acidic silica sol, or alkaline silica sol. For example, the vanadium-resistant catalytic cracking catalyst comprises 25-50 wt% molecular sieve, 5-30 wt% boehmite, 3-20 wt% aluminum sol, 10-35 wt% silica sol, 10-40 wt% kaolin, and 0.5-5 wt% alkaline earth metal oxides.

6. The vanadium-resistant catalytic cracking catalyst according to any one of claims 1-5, characterized in that, In the rare earth metal modified molecular sieve: the mass percentage of rare earth elements distributed on the outer surface of the rare earth metal modified molecular sieve to the mass percentage of total precipitated rare earth elements in the rare earth metal modified molecular sieve is 1.3 or higher, for example, 1.4-2.1; In the vanadium poisoning catalytic cracking catalyst: the mass percentage of alkaline earth elements distributed on the outer surface of the vanadium poisoning catalytic cracking catalyst to the total mass percentage of alkaline earth elements in the vanadium poisoning catalytic cracking catalyst is 1.1-2.1:1, for example, 1.5-1.9:

1.

7. A method for preparing a vanadium-resistant catalytic cracking catalyst, characterized in that, Includes the following steps: S1. Mix molecular sieve with water to obtain slurry A, and filter to obtain filter cake A; S2. Filter cake A is washed and filtered using an alkaline solution to obtain filter cake B; S3. The filter cake B was washed with rare earth metal salt solution A, dried, and calcined to obtain rare earth modified molecular sieve. S4. Rare earth modified molecular sieve, silicon-aluminum material and water are mixed to obtain slurry B, and spray dried to obtain particles A; S5. Selectively roast particle A to obtain particle B, mix it with ammonium salt and water for ammonium exchange, dry it, and roast it a second time to obtain particle C. S6. Mix particles C with water to obtain slurry C, and filter to obtain filter cake C; S7. Filter cake C is washed and filtered using an alkaline solution to obtain filter cake D; S8. The filter cake D is washed, filtered, dried, and calcined using alkaline earth metal salt solution B to obtain the catalytic cracking catalyst.

8. The method for preparing the vanadium poisoning-resistant catalytic cracking catalyst according to claim 7, characterized in that, In step S1, the molecular sieve is a Y-type molecular sieve and a ZSM-5 type molecular sieve, wherein the mass ratio of the Y-type molecular sieve to the ZSM-5 type molecular sieve is 1:1-2:

1.

9. The method for preparing the vanadium poisoning-resistant catalytic cracking catalyst according to claim 7, characterized in that, In step S2, the alkaline solution is an ammonia solution and / or an ammonium carbonate solution, the pH value of the alkaline solution is 8-9 or 9-10; the weight ratio of the alkaline solution to the filter cake A on a dry basis is 0.5:1-3:

1.

10. The method for preparing the vanadium poisoning-resistant catalytic cracking catalyst according to claim 7, characterized in that, In step S3, the concentration of rare earth salts in the rare earth salt solution A is 10-30 wt%. Preferably, in step S3, the drying temperature is 100-150℃; the calcination temperature is 400-600℃, and the calcination time is 1-6 hours.

11. The method for preparing the vanadium poisoning-resistant catalytic cracking catalyst according to claim 7, characterized in that, In step S5, particles B, ammonium salt, and water are mixed in a weight ratio of 1:(0.2-2):(5-18) for ammonium exchange. The conditions for ammonium exchange include a temperature of 50-100°C and a time of 0.5-2 hours. The ammonium salt is selected from one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate. Preferably, in step S5, the drying temperature is 100-150℃; the temperatures of the first and second roasting are each 400-600℃, the roasting time is 1-6 hours, and the roasting atmosphere is air.

12. The method for preparing the vanadium poisoning-resistant catalytic cracking catalyst according to claim 7, characterized in that, In step S7, the alkaline solution is an ammonia solution and / or an ammonium carbonate solution, and the pH value of the alkaline solution is 8-9 or 9-10; the weight ratio of the alkaline solution to the filter cake C on a dry basis is 0.5:1-3:

1.

13. The method for preparing the vanadium poisoning-resistant catalytic cracking catalyst according to claim 7, characterized in that, In step S8, the concentration of alkaline earth metal salt in the alkaline earth metal salt solution B is 15-35 wt%. Preferably, in step S8, the drying temperature is 100-150℃; the calcination temperature is 400-600℃, the calcination time is 1-6 hours, and the calcination atmosphere is air.

14. The method for preparing the vanadium poisoning-resistant catalytic cracking catalyst according to claim 7, characterized in that, The rare earth elements introduced in step S3 account for 0.5-8% of the dry weight of the molecular sieve, calculated as RE2O3, and the alkaline earth metals introduced in step S8 account for 0.1-5% of the dry weight of the catalyst, calculated as alkaline earth metal oxides.

15. The vanadium-resistant catalytic cracking catalyst prepared by the method according to any one of claims 7-14.

16. The application of the vanadium-resistant catalytic cracking catalyst according to any one of claims 1 to 6 or claim 15 in the catalytic cracking of vanadium-containing feedstock oil.

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