A catalytic cracking catalyst resistant to metal pollution and its preparation method

Abstract

The present invention belongs to the field of catalytic cracking technology and relates to a catalytic cracking catalyst resistant to metal contamination and a preparation method thereof. The method comprises mixing unmodified NaY molecular sieve with a binder, clay, and water, slurrying, spray drying, and calcining to obtain catalyst microspheres; then performing ion exchange modification, mild hydrothermal ultrastabilization modification, and SiCl4 vapor phase ultrastabilization modification, treating with a mixed solution of a rare earth salt and an alkaline earth metal salt, and then contacting with aqueous ammonia. The catalyst preparation method can produce a catalytic cracking catalyst having a large pore volume and specific surface area, good strength, strong heavy oil conversion capacity, high gasoline yield, high total liquid yield, and good coke selectivity. The catalyst is also highly resistant to nickel and vanadium contamination.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic cracking, and relates to a catalytic cracking catalyst resistant to metal pollution used in the petroleum processing process and a preparation method thereof. Background Art

[0002] With the recent increase in the heaviness and degradation of crude oil worldwide, the importance of catalytic cracking (FCC) technology, which blends or fully refines heavy oil and residual oil, has become particularly important. Compared to distillate catalytic cracking feedstocks, heavy oil or residual oil contains far more harmful metals than distillates. Harmful metals such as nickel, vanadium, iron, sodium, and calcium, present in feedstocks in the form of porphyrin compounds, cyclohexane salts, and inorganic salts, decompose during the catalytic cracking reaction and accumulate on the balancer. These metals interact with the molecular sieve, disrupting the catalyst's lattice structure and weakening its acidity, resulting in reduced catalyst activity and selectivity, which in turn affects product distribution and quality. Effectively inhibiting heavy metal contamination of catalysts is a key measure for improving the economic and technical benefits of RFCC units.

[0003] CN1854255A discloses a method for preparing a heavy metal-resistant cracking catalyst. The method comprises uniformly mixing clay, deionized water, and optional additives to produce a clay slurry; uniformly mixing a molecular sieve, deionized water, and optional additives to produce a molecular sieve slurry; and uniformly mixing a binder, deionized water, an alkaline earth metal compound, a rare earth metal compound, and an optional inorganic acid to produce a binder slurry. The clay slurry, molecular sieve slurry, and binder slurry are uniformly mixed and then dried. The cracking catalyst prepared by this method has good resistance to nickel and vanadium pollution. When the nickel content on the catalyst is high, it can still maintain a high conversion rate and light oil yield. However, its nickel and vanadium pollution resistance is still subject to certain limitations, and its cracking reaction performance cannot be further improved.

[0004] The metal pollution-resistant catalyst containing rare earth and alkaline earth metals prepared by the prior art has certain anti-pollution performance, but there is no disclosure on how to further enhance the cracking reaction performance under the condition of metal pollution. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a catalytic cracking catalyst with better resistance to metal pollution in view of the problems existing in the prior art.

[0006] The present invention provides a method for preparing a catalytic cracking catalyst resistant to metal pollution, the method comprising the following steps:

[0007] (1) Preparation of catalyst microspheres: Unmodified NaY molecular sieve is mixed with a binder, clay and water, beaten and spray-dried to form, and then calcined in a calciner at 280-380° C. for preferably 1-4 hours to obtain catalyst microspheres A; wherein, on a dry basis, the weight ratio of the binder to the unmodified NaY molecular sieve is preferably 10-45:10-50, and the weight ratio of the clay to the unmodified NaY molecular sieve is preferably 10-80:10-50, for example, 20-60:15-50;

[0008] (2) Ion exchange modification: Catalyst microspheres A are contacted with a rare earth solution to undergo an ion exchange reaction, filtered, and washed to obtain catalyst microspheres B containing rare earth with reduced sodium oxide content; wherein the rare earth solution is also called a rare earth salt solution;

[0009] (3) moderate hydrothermal ultrastable modification: the catalyst microspheres B are subjected to a moderate hydrothermal ultrastable modification treatment, and optionally dried to obtain catalyst microspheres C, wherein the moderate hydrothermal ultrastable modification treatment is performed by calcining the catalyst microspheres B at a temperature of 350-450° C. in an atmosphere containing 40-60% by volume of water vapor (also referred to as a 40-60% by volume water vapor atmosphere or 40-60% water vapor) for 4-6 hours;

[0010] (4) SiCl4 gas phase ultrastable modification: the catalyst microspheres C are contacted with SiCl4 gas at a temperature of 250-450°C for reaction, wherein the weight ratio of SiCl4: catalyst microspheres C on a dry basis is preferably 0.03-0.2:1, and the reaction time is preferably 10 minutes to 5 hours, and then washed and filtered to obtain catalyst microspheres D; wherein the water content of the catalyst microspheres C is preferably not more than 1% by weight; if the water content of the catalyst microspheres C obtained in step (3) does not exceed 1% by weight, they can be directly used for contact with silicon tetrachloride to carry out the reaction; if the water content of the catalyst microspheres C obtained in (3) exceeds 1% by weight, the catalyst microspheres C are dried to make their water content less than 1% by weight and then contacted with silicon tetrachloride for reaction;

[0011] (5) Surface modification: The catalyst microspheres D are contacted with a solution containing a rare earth salt and an alkaline earth metal salt at room temperature for a contact time of 5-30 minutes. For example, the catalyst microspheres D are added to a solution containing a rare earth salt and an alkaline earth metal salt (also referred to as a mixed solution containing a rare earth salt and an alkaline earth metal salt) and stirred for, for example, 5-30 minutes, then filtered, and then contacted with aqueous ammonia for a contact time of, for example, 5-30 minutes. For example, the filter cake is added to aqueous ammonia with a concentration of 5% to 15% by weight, stirred for 5-30 minutes, filtered, dried, and optionally calcined to obtain the finished catalyst product E. The mixed solution of rare earth salt and alkaline earth metal salt is preferably an aqueous solution containing rare earth salt and alkaline earth metal salt. The rare earth salt is, for example, lanthanum nitrate and / or lanthanum chloride, and the alkaline earth metal salt is, for example, magnesium nitrate and / or magnesium chloride. The room temperature is preferably 10-30°C.

[0012] In the preparation method of the catalytic cracking catalyst provided by the present invention, based on the dry weight of the catalyst microspheres A, the catalyst microspheres A contain 10% to 50% by weight of unmodified NaY molecular sieve, 10% to 40% by weight of a binder, and 10% to 80% by weight of clay.

[0013] In the method for preparing a catalytic cracking catalyst provided by the present invention, the catalyst microspheres A may further contain other molecular sieves in addition to the unmodified NaY molecular sieve, with the content of the other molecular sieves on a dry basis being, for example, 0 to 40% by weight, for example, 0 to 30% by weight or 1 to 20% by weight, based on the weight of the catalyst. The other molecular sieves may be molecular sieves used in catalytic cracking catalysts, for example, one or more zeolites having an MFI structure, such as HZSM-5, ZRP, and ZSP, the Beta zeolite, such as Hβ, or the non-zeolitic molecular sieves, such as aluminum phosphate molecular sieves (AlPO molecular sieves) and silicon aluminum phosphate molecular sieves (SAPO molecular sieves).

[0014] The present invention provides a method for preparing a catalytic cracking catalyst, wherein the content of the unmodified NaY molecular sieve in the catalyst microspheres A is 10 to 50% by weight, preferably 15 to 45% by weight, for example 25 to 40% by weight, on a dry basis. The unmodified NaY molecular sieve refers to the original synthesized NaY molecular sieve that has not been modified in any other way except washing with water. For example, the unmodified NaY molecular sieve is a hydrothermally synthesized NaY molecular sieve that has only been washed with industrial water and the pH of the filter cake of the NaY molecular sieve after washing is 7.0 to 9.0, preferably 7.0 to 8.0. The hydrothermally synthesized NaY molecular sieve can be purchased commercially or synthesized with reference to existing techniques, for example, with reference to the methods provided in the claims or examples of U.S. Patents US3639099 and US3671191.

[0015] In the method for preparing a catalytic cracking catalyst provided by the present invention, the clay is selected from one or more clays used as cracking catalyst components, such as kaolin, halloysite, montmorillonite, diatomaceous earth, halloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite, and bentonite. These clays are well known to those skilled in the art. Preferably, the clay content in the catalytic cracking catalyst provided by the present invention is 20 to 55% by weight or 30 to 50% by weight, calculated on a dry basis.

[0016] In the method for preparing a catalytic cracking catalyst provided by the present invention, the binder is one or more of a silicon-based binder, an aluminum-based binder, a zirconium-based binder, or a silicon-aluminum binder. The silicon-based binder may be, for example, silica sol; the aluminum-based binder may be, for example, one or more of alumina sol, pseudo-boehmite, and alumina gel; the zirconium-based binder may be, for example, zirconium sol; and the silicon-aluminum binder may be, for example, silicon-alumina sol or silicon-alumina gel.

[0017] In one embodiment of the method for preparing a catalytic cracking catalyst provided by the present invention, the binder is an aluminum-based binder, also known as an alumina binder. The content of the alumina binder in the catalyst microspheres A, calculated on a dry basis, is 10 to 40% by weight, for example, 20 to 35% by weight. The alumina binder of the present invention is selected from one or more of various forms of alumina, hydrated alumina, and alumina sol commonly used in cracking catalysts. For example, the alumina binder is selected from one or more of γ-alumina, η-alumina, θ-alumina, χ-alumina, pseudoboemite, boehmite, gibbsite, Bayerite, or alumina sol. The weight ratio of the alumina binder to the unmodified NaY molecular sieve is 10-40:10-50, for example, 15-35:20-45, preferably 20-30:25-40, calculated on a dry basis. The alumina binder is preferably pseudo-boehmite and aluminum sol. For example, the catalytic cracking catalyst contains 2-15 weight % and preferably 3-10 weight % of aluminum sol on a dry basis, and 10-30 weight % and preferably 15-25 weight % of pseudo-boehmite on a dry basis.

[0018] When the binder is an aluminum-based binder, preferably aluminum sol and pseudo-boehmite, the slurry can be prepared by slurrying clay, such as kaolin and / or other clay, with the aluminum sol; slurrying alumina and / or an alumina precursor, such as pseudo-boehmite, with hydrochloric acid, preferably with an acid-to-aluminum ratio of 0.10 to 0.30 (molar ratio of acid to pseudo-boehmite calculated as alumina); then mixing the two slurries and slurrying with unmodified NaY molecular sieve or unmodified NaY molecular sieve slurry to obtain a catalyst colloid. The catalyst colloid preferably has a solids content of 28 to 40% by weight.

[0019] The method for preparing a catalytic cracking catalyst provided by the present invention can be operated without heating and aging by using an aluminum-based binder. No heating during the mixing and beating process is beneficial to reducing energy consumption, and can also avoid the slurry viscosity being too high and unable to be transported due to heating, which is beneficial to increasing the solid content of the slurry, thereby helping to reduce production costs and improve production efficiency. In one embodiment, the mixing and beating is to mix the unmodified NaY molecular sieve with the alumina binder, clay and water at ambient temperature, such as room temperature (room temperature 10-30°C), and then stir for more than 30 minutes, such as 30-180 minutes or 30-60 minutes for beating. The mixing and beating process can be performed without heating and aging.

[0020] In one embodiment, the binder is a silica-based binder, such as one or more of silica gel and silica sol, preferably silica sol, such as acidic silica sol, alkaline silica sol, or neutral silica sol. The weight ratio of silica sol to unmodified NaY molecular sieve on a dry basis is 5-45:10-50, for example, 15-30:20-50. Preferably, when silica sol is included, a pseudo-boehmite binder is also used, with the weight ratio of the pseudo-boehmite binder on a dry basis to the silica sol on a dry basis being 0.1 to 1:1.

[0021] The method provided by the present invention for mixing and slurrying unmodified NaY molecular sieve with a binder, clay, and water does not require any special requirements compared to existing catalytic cracking catalyst preparation methods. The resulting slurry preferably has a solids content of 28 to 40% by weight.

[0022] In the method for preparing a catalytic cracking catalyst provided by the present invention, the calcination temperature for preparing the catalyst microspheres A in step (1) is preferably 280-380° C., for example, 300-350° C. The calcination time is preferably 1-4 hours, for example, 2-3 hours.

[0023] According to the method for preparing catalytic cracking catalyst provided by the present invention, there are no special requirements for the spray drying method, and it can be carried out according to the spray drying method in the existing cracking catalyst preparation process.

[0024] In the method for preparing a catalytic cracking catalyst provided by the present invention, the temperature of the ion exchange reaction in step (2) (also referred to as the exchange temperature) is 20 to 60° C., preferably 25 to 45° C., and the exchange time is preferably 90 to 120 minutes. The rare earth solution is an aqueous solution of a rare earth salt; the rare earth salt is preferably rare earth chloride and / or rare earth nitrate.

[0025] In one embodiment, the concentration of the rare earth solution in step (2) is 200-350 g / L in terms of RE2O3, and the weight ratio of the rare earth solution to the catalyst microspheres A is preferably 0.03-0.3.

[0026] Preferably, the ion exchange is performed so that the rare earth content in the obtained catalytic cracking catalyst microspheres B is preferably 1 to 5% by weight in terms of RE2O3.

[0027] In the method for preparing the catalytic cracking catalyst provided by the present invention, the temperature of the mild hydrothermal ultrastable modification treatment is 350-450°C, preferably 370-420°C.

[0028] In the catalytic cracking catalyst provided by the present invention, the moderate hydrothermal ultrastable modification treatment atmosphere comprises an atmosphere containing 40 to 60% by volume of water vapor, preferably an atmosphere containing 45 to 55% by volume of water vapor. Other gases in the atmosphere may be, for example, one or more of air, nitrogen, and helium.

[0029] In the method for preparing the catalytic cracking catalyst provided by the present invention, the mild hydrothermal ultrastable modification treatment time is 4 to 6 hours, preferably 5 to 6 hours.

[0030] In the method for preparing the catalytic cracking catalyst provided by the present invention, the temperature for the contact reaction between the catalyst microspheres C and the SiCl4 gas is 250-450°C, preferably 280-420°C.

[0031] In the method for preparing the catalytic cracking catalyst provided by the present invention, the time (reaction time) for the catalyst microspheres C to contact and react with the SiCl4 gas is 10 minutes to 5 hours, for example, 0.2-2 hours, preferably 0.5 to 2 hours.

[0032] In the method for preparing a catalytic cracking catalyst provided by the present invention, the weight ratio of the reaction materials in the contact reaction between the catalyst microspheres C and SiCl4 gas is 0.05-0.2:1, and the preferred weight ratio of SiCl4:catalyst microspheres is 0.07-0.15:1.

[0033] In the method for preparing a catalytic cracking catalyst provided by the present invention, the washing method described in step (4) is preferably washing with water. In one embodiment, the washing conditions are: catalyst: H2O = 1:8-12, the pH value is preferably 3.0-4.0, and the washing temperature is 20-50°C. The water can be acidic water such as decationized water.

[0034] Preferably, the sodium oxide content in the obtained catalytic cracking catalyst does not exceed 0.15% by weight.

[0035] According to the present invention, the rare earths such as La, Ce, Pr, Nd and one or more mixed rare earths including the above rare earth elements, and the alkaline earth metals such as Be, Mg, Ca, Sr, Ba are preferably Mg and / or Ca.

[0036] In the method for preparing a catalytic cracking catalyst provided by the present invention, in the mixed solution of rare earth salts and alkaline earth metal salts described in step (5), the rare earth salts may be nitrates and / or chlorides of rare earths, for example, the rare earth salts are preferably lanthanum nitrate and / or lanthanum chloride, and the alkaline earth metal salts, for example, alkaline earth metal nitrates and / or chlorides, are preferably magnesium nitrate or magnesium chloride. The concentration of the rare earth salt in the solution containing the rare earth salts and alkaline earth metal salts (calculated as RE2O3) is 60-150 g / L, and the concentration of the alkaline earth metal salt is 30-80 g / L, calculated as alkaline earth metal oxide (calculated as divalent alkaline earth metal oxide, for example, Mg salts are calculated as MgO, and Ca salts are calculated as CaO).

[0037] The ammonia water in step (5) is an aqueous solution of ammonia gas, and the temperature can be room temperature, which is 10-30° C. Preferably, the concentration of the ammonia water is 5-15% by weight in terms of NH 3 .

[0038] In step (5), the weight ratio of the mixed solution of the rare earth salt and the alkaline earth metal salt to the catalyst microspheres D on a dry basis can be 2 to 5:1.

[0039] In one embodiment, the rare earth content (in terms of RE2O3) in the catalyst product E obtained in step (5) is 0.2 wt% to 1.0 wt% higher than the rare earth content in the catalyst microspheres D, that is, the rare earth percentage in the catalyst product E minus the rare earth percentage in the catalyst microspheres D is 0.2 wt% to 1.0 wt%.

[0040] Preferably, in the catalytic cracking catalyst obtained by the method provided by the present invention, the rare earth content calculated as RE2O3 is 1.0 to 6 weight %, for example, 1.2 to 5.8 weight %, and the content of alkaline earth metal oxide is 0.01 to 1 weight %.

[0041] The present invention provides a method for preparing a catalytic cracking catalyst resistant to metal pollution. The method comprises mixing an union-exchanged NaY molecular sieve with a binder, clay, and water, beating, spray drying, and calcining to obtain catalyst microspheres. The method then performs ion exchange modification, moderate hydrothermal ultrastable modification, and SiCl4 gas phase ultrastable modification. The method further comprises subjecting the catalyst to a mixed solution of a rare earth salt and an alkaline earth metal salt and then contacting the catalyst with aqueous ammonia to prepare a catalytic cracking catalyst having a larger pore volume and specific surface area and better strength. The prepared catalytic cracking catalyst is used for catalytic cracking of heavy oil, and has a strong heavy oil conversion capacity, a high gasoline yield, a high light oil yield, a high total liquid yield, and a good coke selectivity. Furthermore, the catalytic cracking catalyst obtained by the method provided by the present invention has a strong resistance to metal pollution, especially strong resistance to nickel and vanadium pollution. In the case of metallic nickel and vanadium pollution, the catalyst has a stronger heavy oil conversion capacity and a better coke selectivity than a catalytic cracking catalyst with the same or similar composition. The catalyst has a higher gasoline yield and a higher activity stability for heavy oil cracking. The catalytic cracking catalyst preparation method provided by the present invention not only has strong metal pollution resistance and low sodium oxide content, but also effectively solves the ammonia nitrogen pollution problem that needs to be solved urgently in the production of catalytic cracking catalysts. DETAILED DESCRIPTION

[0042] The present invention will be further described in the following examples, but are not intended to limit the present invention.

[0043] In the embodiments and comparative examples, the unmodified NaY molecular sieve (also known as NaY zeolite) was provided by the Qilu Branch of Sinopec Catalyst Co., Ltd., and had a sodium oxide content of 13.5% by weight, a framework silicon-aluminum ratio (SiO2 / Al2O3 molar ratio) of 4.6, a unit cell constant of 2.470 nm, and a relative crystallinity of 90%. It was the original synthesized NaY molecular sieve washed with industrial water, and the pH value of the filter cake after washing was 7.6; magnesium chloride, magnesium nitrate, lanthanum chloride, and lanthanum nitrate were chemically pure reagents produced by Beijing Chemical Plant, and rare earth chloride and rare earth nitrate (respectively designated as RECl3 and RE(NO3)3, mixed rare earths, wherein the La2O3 content was 33.6% by weight and the Ce2O3 content was 66.4% by weight) were industrial products produced by Baotou Steel Rare Earth Company. Pseudo-boehmite is an industrial product produced by Shandong Aluminum Plant, with a solid content of 61% by weight; kaolin is special kaolin for cracking catalyst produced by Suzhou China Kaolin Company, with a solid content of 76% by weight; aluminum sol is provided by Qilu Branch of Sinopec Catalyst Co., Ltd.; silica sol is provided by Qilu Branch of Sinopec Catalyst Co., Ltd., with a silicon oxide content of 25% by weight and a pH value of 2.5.

[0044] Analytical Methods: In the comparative examples and examples, the elemental content of the catalysts was determined by X-ray fluorescence spectroscopy; the unit cell constant and relative crystallinity of the zeolite in the catalysts were determined by X-ray powder diffraction (XRD) using the RIPP 145-90 and RIPP 146-90 standard methods (see "Analytical Methods in Petrochemical Industry" (RIPP Test Methods), edited by Yang Cuiding et al., Science Press, 1990). The specific surface area of ​​the catalysts was measured using a Quantachrome Autosorb-1 nitrogen adsorption-desorption instrument according to GB / T 5816-1995. Samples were degassed at 300°C for 6 hours before testing. The total pore volume of the catalysts was measured according to the RIPP 151-90 standard method (see "Analytical Methods in Petrochemical Industry" (RIPP Test Methods), edited by Yang Cuiding et al., Science Press, 1990). The wear index of the catalyst (used to characterize the wear resistance, the smaller the wear index, the better the wear resistance) was tested according to the RIPP29-90 standard method (see "Petrochemical Analysis Methods" (RIPP Test Method), edited by Yang Cuiding et al., Science Press, published in 1990).

[0045] Unless otherwise specified, the chemical reagents used in the comparative examples and examples are of chemically pure quality.

[0046] Example 1

[0047] (1) Add 116 kg of decationized water to the catalyst gelling kettle, and then add the gelling raw materials in sequence under stirring: 42.4 kg of kaolin (solid content of 76% by weight, purchased from Suzhou Kaolin Company), 16.3 kg of aluminum sol (alumina content of 21.5% by weight, provided by Sinopec Catalyst Co., Ltd. Qilu Branch), 25.3 kg of pseudo-boehmite (solid content of 61% by weight, purchased from Shandong Aluminum Plant) and 5.2 L of hydrochloric acid (HCl content of 31% by weight), and stir rapidly for 150 minutes. Then add 18.9 kg (based on NaY dry basis) of unmodified NaY molecular sieve slurry (NaY molecular sieve concentration of 53% by weight, provided by Sinopec Catalyst Co., Ltd. Qilu Branch), and stir rapidly for 60 minutes. Then spray dry and form, and roast in a roasting furnace at 320 ° C for 1 hour to obtain catalyst microspheres A1;

[0048] (2) The catalyst microspheres A1 prepared above were added to 700 L of decationized aqueous solution and stirred to mix evenly, and 5.91 L of RE(NO3)3 solution (the rare earth solution concentration was 330 g / L in terms of RE2O3) was added and stirred. The mixture was heated to 30°C and maintained for 1 h, and then filtered and washed. The filter cake was dried at 120°C to obtain catalyst microspheres B1 containing rare earth with reduced sodium oxide content.

[0049] (3) calcining the catalyst microspheres B1 at 410° C. in an atmosphere containing 45% by volume of water vapor for 6 h, and then drying the catalyst microspheres to a water content of less than 1% by weight to obtain catalyst microspheres C1;

[0050] (4) introducing heated vaporized SiCl4 gas at a weight ratio of SiCl4 to catalyst microspheres C1 (on a dry basis) of 0.05:1, reacting at 400°C for 20 minutes, then washing with 700 L of decationized water and filtering to obtain catalyst microspheres D1;

[0051] (5) 20 kg of catalyst microspheres D1 were added to 60 L of an aqueous solution containing LaCl3 (concentration of 100 g / L as La2O3) and MgCl2 (concentration of 55 g / L as MgO) at 25°C, stirred for 5 minutes, and filtered. The solution was then added to 60 L of 8 wt% ammonia water, stirred for 5 minutes, filtered, dried, and calcined at 550°C for 2 hours to obtain the finished catalyst SCAT-1. The performance analysis results are shown in Table 1.

[0052] Example 2

[0053] (1) Add 120 kg of decationized water to the catalyst gelling kettle, and then add the gelling raw materials in sequence under stirring: 44.2 kg of kaolin (solid content of 76% by weight, purchased from Suzhou Kaolin Company), 13 kg of aluminum sol (alumina content of 21.5% by weight, provided by Sinopec Catalyst Co., Ltd. Qilu Branch), 26.4 kg of pseudo-boehmite (solid content of 61% by weight, purchased from Shandong Aluminum Plant) and 5.4 L of hydrochloric acid (HCl content of 31% by weight), and stir for 150 minutes. Then add 17.5 kg (based on NaY dry basis) of unmodified NaY molecular sieve slurry (concentration of 53% by weight), provided by Sinopec Catalyst Co., Ltd. Qilu Branch), and stir for 60 minutes. Then spray dry and form, and calcine in a calciner at 350 ° C for 1 hour to obtain catalyst microspheres A2;

[0054] (2) The catalyst microspheres A2 prepared above were added to 700 L of decationized aqueous solution and stirred to mix evenly, 4.66 L of RE(NO3)3 solution (the rare earth solution concentration was 330 g / L in terms of RE2O3) was added, stirred, and heated to 40°C for 1 h, then filtered and washed, and the filter cake was dried at 120°C to obtain catalyst microspheres B2 containing rare earth with reduced sodium oxide content;

[0055] (3) The catalyst microspheres B2 were calcined at 350° C. in an atmosphere containing 55% by volume of water vapor for 6 h, and then dried to reduce the water content to less than 1% by weight to obtain catalyst microspheres C2 containing a molecular sieve with a reduced unit cell constant.

[0056] (4) According to the weight ratio of SiCl4:catalyst microspheres C2 (dry basis) = 0.08:1, heated and vaporized SiCl4 gas was introduced, and the reaction was carried out at a temperature of 300°C for 2 hours. After that, the catalyst microspheres D2 were washed with 700 L of decationized water and filtered.

[0057] (5) 20 kg of catalyst microspheres D2 were added to 70 L of an aqueous solution containing La(NO3)3 (concentration of 80 g / L as La2O3) and Mg(NO3)2 (concentration of alkaline earth metal solution as MgO of 45 g / L) at 25°C, stirred for 10 minutes, and filtered. The solution was then added to 70 L of aqueous ammonia containing 12.5% ​​by weight of NH3, stirred for 10 minutes, filtered, dried, and calcined at 550°C for 2 hours to obtain the finished catalyst SCAT-2. The performance analysis results are shown in Table 1.

[0058] Example 3

[0059] (1) Add 133 kg of decationized water to the catalyst gelling kettle, and then add the gelling raw materials in sequence under stirring: 38.7 kg of kaolin (solid content of 76% by weight, purchased from Suzhou Kaolin Company), 13 kg of aluminum sol (alumina content of 21.5%, provided by Sinopec Catalyst Co., Ltd. Qilu Branch), 28.7 kg of pseudo-boehmite (solid content of 61% by weight, purchased from Shandong Aluminum Plant) and 5.9 L of hydrochloric acid (HCl content of 31% by weight), and stir rapidly for 150 minutes. Then add 20.3 kg (based on NaY dry basis) of unmodified NaY molecular sieve slurry (concentration of 53% by weight), provided by Sinopec Catalyst Co., Ltd. Qilu Branch), and stir for 60 minutes. Then spray dry and form, and roast in a roasting furnace at 300 ° C for 1 hour to obtain catalyst microspheres A3;

[0060] (2) The catalyst microspheres A3 prepared above were added to 700 L of decationized aqueous solution and stirred to mix evenly, and 7.53 L of RE(NO3)3 solution (the rare earth solution concentration was 330 g / L in terms of RE2O3) was added and stirred. The mixture was heated to 35°C and maintained for 1 h. The mixture was then filtered and washed, and the filter cake was dried at 120°C to obtain catalyst microspheres B3 containing rare earth with reduced sodium oxide content.

[0061] (3) The catalyst microspheres B3 were calcined at 390° C. in an atmosphere containing 50% by volume of water vapor and 50% by volume of air for 5 h, and then dried to reduce the water content to less than 1% by weight, to obtain catalyst microspheres C3 containing a molecular sieve with a reduced unit cell constant.

[0062] (4) According to the weight ratio of SiCl4:catalyst microspheres C3 (dry basis) = 0.10:1, heated and vaporized SiCl4 gas was introduced, and the reaction was carried out at a temperature of 350°C for 1 hour. After that, the catalyst microspheres D3 were washed with 700 L of decationized water and filtered.

[0063] (5) 20 kg of catalyst microspheres D3 were added to 45 L of a mixed solution containing LaCl3 (concentration of 120 g / L as La2O3) and MgCl2 (concentration of 60 g / L as MgO) at 25°C, stirred for 5 minutes, and filtered. The mixture was then added to 50 L of ammonia water containing 10 wt% NH3, stirred for 5 minutes, filtered, dried, and calcined at 550°C for 2 hours to obtain the finished catalyst SCAT-3. The performance analysis results are shown in Table 1.

[0064] Example 4

[0065] A catalyst was prepared by the method of Example 1, except that the pseudo-boehmite was replaced with silica sol in an amount equal to the weight on a dry basis. The resulting catalytic cracking catalyst was designated SCAT-4.

[0066] Comparative Example 1

[0067] 2000 g of NaY molecular sieve (on a dry basis) was added to 20 liters of decationized aqueous solution and stirred to mix evenly. 580 ml of RE(NO3)3 solution (the rare earth solution concentration was 330 g / L in terms of RE2O3) was added and stirred. The mixture was heated to 90-95°C and maintained for 1 hour. The mixture was then filtered and washed. The filter cake was dried at 120°C and then calcined at 390°C in an atmosphere containing 60% by volume of water vapor and 40% by volume of air for 5 hours. The mixture was then dried to a water content of less than 1% by weight. SiCl4 gas vaporized by heating was then introduced at a weight ratio of SiCl4:Y molecular sieve (on a dry basis) of 0.45:1. The mixture was reacted at 400°C for 2 hours. The mixture was then washed with 20 liters of decationized water and filtered to obtain a modified Y molecular sieve, designated DZ1.

[0068] 714.5 grams of alumina sol with a 21% aluminum oxide content was added to 1565.5 grams of decationized water, stirred, and then 2763 grams of kaolin with a 76% solids content was added and dispersed for 60 minutes. 2049 grams of pseudo-boehmite with a 61% aluminum oxide content was added to 8146 grams of decationized water, and 210 ml of 36% hydrochloric acid was added while stirring. After acidification for 60 minutes, the dispersed kaolin slurry was added, followed by 1500 grams (dry basis) of ground DZ1 molecular sieve. After uniform stirring, the mixture was spray-dried, washed, and dried to obtain a catalyst, designated DC1. The DC1 catalyst contained, on a dry basis, 30% by weight of DZ1 molecular sieve, 42% by weight of kaolin, 25% by weight of pseudo-boehmite, and 3% by weight of alumina sol.

[0069] Comparative Example 2

[0070] Take 2000 grams of NaY molecular sieve (on a dry basis) and add it to 25 liters of decationized aqueous solution and stir to mix it evenly. Then add 681 ml of RECl3 solution (the solution concentration is 330 g / L based on RE2O3), stir, heat to 90-95°C and hold for 1 hour, then filter and wash. The filter cake is dried at 120°C and then calcined at a temperature of 440°C in an atmosphere containing 70% by volume of water vapor for 5 hours. After that, it is dried to a water content of less than 1% by weight. Then, according to the weight ratio of SiCl4:Y type zeolite = 0.6:1, heated and vaporized SiCl4 gas is introduced and reacted at a temperature of 460°C for 2 hours. After that, it is washed with 20 liters of decationized water and then filtered to obtain modified molecular sieve DZ2.

[0071] Referring to the preparation method of Comparative 1, DZ2 molecular sieve, kaolin, water, pseudo-boehmite binder, and alumina sol were formed into a slurry according to conventional catalytic cracking catalyst preparation methods, and then spray-dried to prepare a microsphere catalyst. The prepared catalytic cracking catalyst was designated DC2. On a dry basis, the DC2 catalyst contained 30% by weight of DZ2 molecular sieve, 42% by weight of kaolin, 25% by weight of pseudo-boehmite, and 3% by weight of alumina sol.

[0072] Comparative Example 3

[0073] The catalyst was prepared according to the method of Example 1 of patent CN1854255A, and the product was recorded as DC3.

[0074] Comparative Example 4

[0075] A catalyst was prepared according to the method of Example 1, except that the spray-dried shaped product was calcined in a calciner at 500°C for 1 hour. The catalyst was designated as DC4.

[0076] Comparative Example 5

[0077] The catalyst was prepared by the method of Example 1, except that the calcination atmosphere in step 3 contained 80% by volume of water vapor and the calcination temperature was 550° C. The catalyst was designated as DC5.

[0078] Examples 5 to 8

[0079] Examples 5-8 are used to illustrate the heavy metal contamination method of the catalyst and the catalytic cracking performance of the catalytic cracking catalyst of the present invention.

[0080] The SCAT-1, SCAT-2, SCAT-3, and SCAT-4 catalysts were first subjected to cyclic contamination (to deposit Ni and V) in a cyclic aging device. The Ni and V contents of the catalysts after cyclic contamination are shown in Table 3. The cyclic contamination step includes: introducing heavy metals (Ni and V) into the catalysts by the Michel impregnation method, and then loading the catalysts with heavy metals into a D-100 device (a small fixed fluidized bed, manufactured by Kayser Technology, Inc. in the United States). The D-100 device is treated according to the following steps:

[0081] (a) Heating to 600°C at a heating rate of 20°C / min under nitrogen atmosphere;

[0082] (b) Heating to 780°C at a rate of 1.5°C / min, then maintaining the temperature at 780°C. During this period, the treatment atmosphere was changed as follows:

[0083] (i) treating the mixture for 10 minutes in an atmosphere containing 40% by volume of nitrogen (wherein the nitrogen contains 5% by volume of propylene) and 60% by volume of water vapor;

[0084] (ii) treating the mixture for 10 minutes in an atmosphere containing 40% by volume of nitrogen (pure nitrogen, propylene-free) and 60% by volume of water vapor,

[0085] (iii) treating the sample with an atmosphere containing 40% by volume of air (containing 4000 μmol / mol SO2) and 60% by volume of water vapor for 10 minutes,

[0086] (IV) treating the sample with an atmosphere containing 40% by volume nitrogen and 60% by volume water vapor for 10 minutes; then repeating steps (i) to (IV) once each in the aforementioned order, and then repeating step (i) to terminate the cyclic contamination step;

[0087] The aging process was then carried out as follows: the contaminated catalyst mixture was circulated and aged at 788° C. for 8 hours in an atmosphere containing 80% by volume of water vapor and 20% by volume of air;

[0088] The catalytic performance of the catalyst after circulating contamination and aging was then investigated on an ACE device. The feed oil entered the bottom of the reactor and came into contact with the catalyst mixture. The catalyst loading was 9 g, the reaction temperature was 500 ° C, and the weight hourly space velocity was 16 h －1 The agent-oil ratio (weight ratio) is 5. The raw material properties of the ACE experiment are shown in Table 2, and the evaluation results are shown in Table 3.

[0089] Among them, conversion rate = gasoline yield + liquefied gas yield + dry gas yield + coke yield

[0090] Total liquid yield = gasoline yield + diesel yield + liquefied gas yield

[0091] Coke selectivity = coke yield / conversion rate

[0092] Dry gas selectivity = dry gas yield / conversion rate

[0093] Comparative Examples 6 to 10

[0094] Comparative Examples 6 to 10 illustrate the catalytic cracking reaction performance of the ultrastable Y-type zeolite prepared by the methods provided in Comparative Examples 1 to 5.

[0095] Catalysts DC1 to DC5 were first subjected to cyclic contamination (to deposit Ni and V) in a cyclic aging apparatus. The Ni and V contents of the catalysts after cyclic contamination are shown in Table 3. The cyclic contamination steps are shown in Example 4. Aging was then performed: the cyclically contaminated catalyst mixture was aged at 788° C. in an atmosphere containing 80% by volume water vapor and 20% by volume air for 8 hours.

[0096] The catalytic performance of the catalyst after circulating contamination and aging was then investigated on an ACE device. The feed oil entered the bottom of the reactor and came into contact with the catalyst mixture. The catalyst loading was 9 g, the reaction temperature was 500 ° C, and the weight hourly space velocity was 16 h －1 The agent-oil ratio (weight ratio) is 5. The raw material properties of the ACE experiment are shown in Table 2, and the evaluation results are shown in Table 3.

[0097] Table 1

[0098]

[0099] From the results listed in Table 1, it can be seen that the catalytic cracking catalyst provided by the present invention has a larger pore volume and specific surface area, and at the same time, has better strength, and the sodium oxide content in the catalyst is low, and the relative crystallinity of the molecular sieve in the catalyst is high.

[0100] Table 2 ACE evaluation of feedstock oil properties

[0101]

[0102] Table 3

[0103]

[0104]

[0105] Table 3 continued

[0106]

[0107] The results listed in Table 3 show that the catalytic cracking catalyst provided by the present invention still has significantly lower coke selectivity and dry gas selectivity after being contaminated by Ni and V and aged, and the total liquid product yield and gasoline yield are high, indicating that the catalytic cracking catalyst provided by the present invention has excellent resistance to Ni and V contamination.

Claims

1. A method for preparing a catalytic cracking catalyst resistant to metal contamination, the method comprising the following steps: (1) Preparation of catalyst microspheres: unmodified NaY molecular sieve is mixed with a binder, clay and water, beaten and spray-dried to form, and calcined at 280-380°C to obtain catalyst microspheres A; wherein, on a dry basis, the weight ratio of the binder to the unmodified NaY molecular sieve is 10-45:10-50, and the weight ratio of the clay to the unmodified NaY molecular sieve is 10-80:10-50; the binder is one or more of a silicon-based binder, an aluminum-based binder, a zirconium-based binder or a silicon-aluminum binder; (2) Ion exchange modification: Catalyst microspheres A are contacted with a rare earth solution to undergo an ion exchange reaction, filtered, and washed to obtain catalyst microspheres B. The temperature of the rare earth ion exchange reaction is 20-60°C, and the exchange time is 90-120 minutes. (3) Mild hydrothermal ultrastable modification: calcining the catalyst microspheres B at a temperature of 350-450° C. in an atmosphere containing 40-60% by volume of water vapor for 4-6 hours, and optionally drying to obtain catalyst microspheres C; the water content in the catalyst microspheres C does not exceed 1% by weight; (4) SiCl4 gas phase ultrastable modification: the catalyst microspheres C are contacted with SiCl4 gas at a temperature of 250 to 450°C for reaction, washed, and filtered to obtain catalyst microspheres D, wherein the weight ratio of SiCl4 to catalyst microspheres C on a dry basis is 0.03 to 0.2:1, and the reaction time is 10 minutes to 5 hours; (5) Surface modification treatment: The catalyst microspheres D are contacted with a solution containing a rare earth salt and an alkaline earth metal salt at room temperature, and then contacted with ammonia water, dried, and optionally calcined to obtain a finished catalyst product E.

2. The method for preparing a catalytic cracking catalyst according to claim 1, wherein: The unmodified NaY molecular sieve described in step (1) refers to the hydrothermally synthesized NaY molecular sieve that is only washed with water and the pH value of the filter cake of the NaY molecular sieve after washing is measured to be 7 to 9; In step (1), the calcination time is 1-4 hours; the calcination temperature is 300-350°C.

3. The method for preparing a catalytic cracking catalyst according to claim 1, wherein: In step (2), the rare earth solution is an aqueous solution of a rare earth salt.

4. The method for preparing a catalytic cracking catalyst according to claim 1, wherein: The calcination temperature in step (3) is 370-420° C., the atmosphere in step (3) contains 45-55% by volume of water vapor, and the calcination time in step (3) is 5-6 hours.

5. The method for preparing a catalytic cracking catalyst according to claim 1, wherein: The washing method described in step (4) is washing with water, and the washing conditions are catalyst: H2O=1:8~12 weight ratio, pH value is 3~4, and washing temperature is 20~50℃.

6. The method for preparing a catalytic cracking catalyst according to claim 1, wherein: In step (5), the catalyst microspheres D are contacted with a solution containing a rare earth salt and an alkaline earth metal salt at room temperature for 5-30 minutes, and then filtered. Then, the catalyst microspheres D are contacted with aqueous ammonia for 5-30 minutes, filtered, dried, and optionally calcined to obtain a finished catalyst product E.

7. The method for preparing a catalytic cracking catalyst according to claim 1, wherein: In step (5), the concentration of the ammonia water is 5 to 15% by weight as NH3.

8. The method for preparing a catalytic cracking catalyst according to claim 1, wherein: The weight ratio of the mixed solution containing rare earth salt and alkaline earth metal salt in step (5) to the catalyst microspheres D on a dry basis is 3 to 6:

1.

9. The method for preparing a catalytic cracking catalyst according to claim 1, wherein: The zirconium-based binder is zirconium sol, and the silica-alumina binder is silica-alumina sol or silica-alumina gel.

10. The method for preparing a catalytic cracking catalyst according to claim 3, characterized in that: The temperature of the ion exchange reaction in step (2) is 25-45° C.; the rare earth salt is rare earth chloride and / or rare earth nitrate.

11. The method for preparing a catalytic cracking catalyst according to claim 3, wherein: In step (2), the rare earth content in the catalyst microspheres B obtained by the exchange is 1 to 5% by weight in terms of RE2O3.

12. The method for preparing a catalytic cracking catalyst according to claim 5, characterized in that: The temperature for the contact reaction between the catalyst microspheres C and the SiCl4 gas in step (4) is 280 to 420° C., the time for the contact reaction between the catalyst microspheres C and the SiCl4 gas in step (4) is 0.5 to 2 hours, and the weight ratio of SiCl4 to the catalyst microspheres C in step (4) is 0.05 to 0.15:

1.

13. The method for preparing a catalytic cracking catalyst according to claim 6, characterized in that: Calculated on the basis of RE2O3, the rare earth content in the catalyst product E in step (5) is 0.2 wt% to 1 wt% higher than the rare earth content in the catalyst microspheres D.

14. The method for preparing a catalytic cracking catalyst according to claim 6, characterized in that: The rare earth salt described in step (5) is lanthanum nitrate and / or lanthanum chloride, and the alkaline earth metal salt is magnesium nitrate and / or magnesium chloride; the concentration of the rare earth salt in the solution containing the rare earth salt and the alkaline earth metal salt is 60-150 g / L in terms of RE2O3, and the concentration of the alkaline earth metal salt is 30-80 g / L in terms of alkaline earth metal oxide.

15. The method for preparing a catalytic cracking catalyst according to claim 9, characterized in that: The silicon-based binder is silica sol, and the aluminum-based binder is one or more of aluminum sol, pseudo-boehmite, and aluminum gel.

16. A catalytic cracking catalyst obtained by the method according to any one of claims 1 to 15; wherein the catalytic cracking catalyst comprises 1 to 6% by weight of rare earth as calculated as RE2O3 and 0.01 to 1% by weight of alkaline earth metal oxide.

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