Preparation method of metal pollution resistant catalytic cracking catalyst

Abstract

The invention discloses a preparation method of a metal-pollution-resistant catalytic cracking catalyst, which comprises the following steps: treating coal series kaolin, carrying out spray granulation on the treated coal series kaolin, a molecular sieve and acidified alumina, discharging the material from a tower, and sequentially contacting with a rare earth salt, a zinc salt and an antimony compound to prepare the metal-pollution-resistant catalytic cracking catalyst. According to the invention, not only is the application scene of coal series kaolin widened, but also passivation elements are positioned at the optimal positions aiming at the metal poisoning mechanism, the utilization rate and effectiveness are improved, and the metal pollution resistance of the catalyst is obviously improved.

Description

Technical Field

[0001] The invention relates to a method for preparing a catalytic cracking catalyst resistant to metal pollution, and belongs to the field of catalytic cracking catalyst preparation. Background Art

[0002] In order to reduce costs and maximize profits, refineries need to process heavy oil or inferior oil products, and inferior oil contains a high proportion of metals, such as vanadium, nickel, iron, calcium, etc. Vanadium compounds are oxidized into V2O5 in the regenerator, which exists in liquid form, flows through the catalyst surface and enters the interior, destroys the molecular sieve crystal structure, and causes the catalyst activity to be significantly reduced; nickel compounds are oxidized in the regenerator, although they are not mobile, but they are reduced by hydrogen in the reaction section, have a dehydrogenation effect, and the hydrogen / methane ratio in the reaction product is significantly increased; iron compounds are oxidized to form low-melting products with silicon oxide and sodium oxide on the catalyst surface, which partially collapse and block the pores, resulting in reduced cracking capacity and increased coke generation; calcium oxides are mainly concentrated at the pores on the catalyst surface, making the pores smaller. From the above, it can be seen that only vanadium can enter the interior of the catalyst particles, and nickel, iron, and calcium are mainly on the surface of the catalyst particles.

[0003] Patent CN115957799A discloses the use of a complex in the preparation of a heavy catalytic cracking catalyst resistant to metal pollution. The complex includes a modified metal ion and a complexing agent. The molar ratio of the complexing agent to the modified metal ion is 0.5:1 to 10:1. The modified metal is one or more of Ti, Mn, Ba, and Ca.

[0004] Patents CN202210237501.6, CN116689017A and CN1854255A all involve a method for preparing a catalytic cracking catalyst that is resistant to metal pollution. In CN202210237501.6, unmodified NaY molecular sieve, binder, clay and water are mixed, pulped and spray dried, roasted, rare earth ion exchanged, moderated hydrothermal modification, gas phase ultra-stable modification, phosphorus introduction, acid treatment, rare earth salt and alkaline earth metal salt treatment and ammonia treatment are carried out. In CN116689017A, catalyst microspheres are treated with organic acid and inorganic acid, first passed through a mixed solution of rare earth salt and alkaline earth metal salt and then contacted with ammonia. CN1854255A mixes clay, deionized water and optional additives to obtain clay slurry, mixes molecular sieve, deionized water and optional additives to obtain molecular sieve slurry, mixes binder, deionized water, alkaline earth metal compound and rare earth metal compound, and optional inorganic acid to obtain binder slurry; and the clay slurry, molecular sieve slurry and binder slurry are mixed uniformly and then dried.

[0005] The above-mentioned existing catalytic cracking catalysts have a certain ability to resist metal pollution, but the anti-metal technology has not been fully considered and realized. The anti-metal active components are evenly distributed in the catalyst particles, and the internal active components do not play their due role, resulting in waste and side effects. Summary of the invention

[0006] In order to solve the deficiencies of the prior art, the present invention provides a method for preparing a catalytic cracking catalyst resistant to metal pollution. The method comprises the following steps:

[0007] (1) Coal-based kaolin that meets the particle size distribution requirements is first calcined, the calcined material is slurried with water, and a certain proportion of phosphoric acid and halloysite are added, stirred for a period of time, and the slurry enters the grinding equipment for processing;

[0008] (2) adding Y-type molecular sieve and acidified alumina to the above-mentioned ground slurry in a certain proportion, stirring evenly, spraying granulation, and controlling the water content of the material at the outlet of the spray tower to be 15-18%;

[0009] (3) The materials discharged from the tower pass through three tiltable drum granulation devices in sequence. Among them, the first device sprays a certain proportion of water-soluble rare earth salts, rare earth hydroxides or rare earth carbonates, the second device sprays a certain proportion of zinc dihydrogen phosphate dissolved in acetic acid, ammonia water or ammonium salts, and the third device sprays a certain proportion of triphenyl antimony. The rotation speed and spraying speed are controlled, and preliminary drying is accompanied by hot air;

[0010] (4) The above materials continuously enter the roasting furnace with segmented temperature control to control the negative pressure in the furnace;

[0011] (5) After calcination, the material is slurried in water, washed, filtered and dried to obtain a metal pollution-resistant catalyst.

[0012] In step (1), the particle size distribution of the coal-bearing kaolin is D50≤15μm, D90≤40μm, the calcination temperature is <900°C, the phosphoric acid addition ratio is 5-10wt% of the dry basis of the coal-bearing kaolin calculated as P2O5, and the addition ratio of halloysite to the coal-bearing kaolin mass ratio is (0.3-0.6):1.

[0013] In step (2), the pore volume of alumina is ≥ 0.55 ml / g, and EDTA is used for acidification in advance, the mass ratio of EDTA to Al2O3 is 0.035-0.08, the proportion of alumina added accounts for 5-15wt% of the final catalyst dry basis, and the proportion of Y-type molecular sieve added accounts for 28-40wt% of the final catalyst dry basis.

[0014] In step (3), the rare earth addition ratio is (0.3-1.2)% of the final catalyst dry basis based on the mass of RE2O3, the zinc dihydrogen phosphate addition ratio is (0.05-0.15)% of the final catalyst dry basis based on the mass of ZnO, and the triphenyl antimony addition ratio is (0.05-0.20)% of the final catalyst dry basis based on the mass of Sb.

[0015] In step (4), the material temperature in the calcining furnace is 450-600°C.

[0016] The present invention is beneficial in that:

[0017] (1) The reserves of coal-based kaolin in my country reach 6 billion tons. Currently, its application is limited to the porcelain industry, with low added value. It is used in the preparation of FCC catalysts without treatment and is fragile. After calcination, it forms active substances. After acid treatment, it has mesoporous characteristics, with a pore size of about 40 angstroms, a significant increase in specific surface area, and unobstructed pores.

[0018] (2) Alumina with a large pore volume reacts with EDTA, and the alumina is partially acidified and connected to grow into a larger lamellar structure, which has adhesive properties. EDTA has a larger molecular space than HCl and HNO3, and the lamellar structure is not so tight. In addition, it can be burned after calcination to form larger pores.

[0019] (3) The order and type of adding anti-metal components are crucial to the effect. The water content of the bottom material is controlled at 15-20wt%, and the pores are filled with appropriate water. The first step is to add rare earth, which is soluble in water. A part of it can enter the pores, not just on the surface. According to the fluidity characteristics of vanadium, zinc and antimony are either slightly soluble in water or insoluble in water. The pores of the catalyst particles are filled with water, making it difficult for zinc and antimony to enter the interior. Basically, they are on the outer surface, which is more effective in combining with nickel and iron. DETAILED DESCRIPTION

[0020] The specific embodiments of the present invention are described in detail below. It should be understood that what is described here is only used to illustrate and explain the present invention, and is not used to limit the present invention. The raw materials used in the examples and comparative examples were all taken from the company's warehouse.

[0021] Methods for metal contamination of catalysts in the laboratory:

[0022] Using the FFB small fixed fluidized bed evaluation device, metals are added to the raw oil in a certain proportion, and the number of cycles is determined based on the final amount of metal. One cycle includes oil feeding, reaction, gas stripping, and regeneration processes.

[0023] Embodiment 1:

[0024] (1) 2218.5 g of coal-based kaolin (ignition loss 24.5%) was weighed and roasted at <900°C, then 6836 g of water was added for slurrying, and 219.2 g of phosphoric acid (85 wt%) and 1322.8 g of halloysite (ignition loss 36.5%) were added, stirred for a period of time, and the slurry was sent to a grinding device for treatment, which was recorded as slurry A;

[0025] (2) Weighing 5147.1 g of Y-type molecular sieve and 962.1 g of acidified alumina, adding them to slurry A, stirring evenly, spraying and granulating, and controlling the water content of the material at the outlet of the spray tower to be 15-18%;

[0026] (3) The material discharged from the tower is sequentially passed through three tiltable drum granulation devices. The first device sprays 116.3 g of rare earth salt solution (RE2O3 = 21.5%), the second device sprays 11.4 g of zinc dihydrogen phosphate (ZnO = 35%) dissolved in acetic acid, ammonia water or ammonium salt, and the third device sprays 14.9 g of triphenyl antimony (97%). The rotation speed and spraying speed are controlled, and hot air is used for preliminary drying;

[0027] (4) continuously placing the above materials into a calcining furnace with segmented temperature control for calcining at a temperature of 450-600° C.;

[0028] (5) After calcination, the material is slurried in water, washed, filtered and dried, and the collected metal pollution-resistant catalyst is recorded as Cat-1.

[0029] Embodiment 2:

[0030] (1) 2457.0 g of coal-based kaolin (ignition loss 24.5%) was weighed and roasted at <900° C., then 6529.6 g of water was added for slurrying, and 300.4 g of phosphoric acid (85 wt%) and 881.9 g of halloysite (ignition loss 36.5%) were added. After stirring for a period of time, the slurry was sent to a grinding device for treatment, which was recorded as slurry A;

[0031] (2) Weighing 5882.4 g of Y-type molecular sieve and 641.4 g of acidified alumina, adding them to slurry A, stirring evenly, spraying and granulating, and controlling the water content of the material at the bottom outlet of the spray tower to be 15-18%;

[0032] (3) The material discharged from the tower is sequentially passed through three tiltable drum granulation devices. The first device sprays 232.6 grams of rare earth salt solution (RE2O3 = 21.5%), the second device sprays 17.1 grams of zinc dihydrogen phosphate (ZnO = 35%) dissolved in acetic acid, ammonia water or ammonium salt, and the third device sprays 22.4 grams of triphenyl antimony (97%). The rotation speed and spraying speed are controlled, and hot air is used for preliminary drying;

[0033] (4) continuously placing the above materials into a calcining furnace with segmented temperature control for calcining at a temperature of 450-600° C.;

[0034] (5) After calcination, the material is slurried in water, washed, filtered and dried, and the collected metal pollution-resistant catalyst is recorded as Cat-2.

[0035] Comparative Example:

[0036] Weigh 874.2 g of kaolin (China Kaolin Company, ignition loss 24.5%), add 1747.2 g of water, 568.7 g of aluminum sol (solid content 21.1%), slurry, stir for > 6 hours, then add 1363.6 g of HCRY molecular sieve (solid content 33%), 446.3 g of pseudo-boehmite (ignition loss 39.5%) in turn, stir for 30 minutes, then add 137.8 g of HCl (14.7%), 55.8 g of rare earth chloride (RE2O3 = 21.5%), spray dry after a period of time, and record it as DB-1.

[0037] Catalyst performance evaluation:

[0038] A FFB small fixed fluidized bed evaluation device was used.

[0039] The properties of the raw oil used for evaluation are as follows:

[0040] Table 1 Basic properties of crude oil

[0041]

[0042] The evaluation results are as follows:

[0043]

[0044] Judging from the evaluation data, gasoline, diesel and total liquid yields are significantly improved compared with the comparison agent, and the coke yield is reduced, indicating that the catalyst prepared by this patent has good application value. Of course, the present invention can also have many other embodiments, and technicians familiar with this field can make various corresponding deformations and adjustments based on the present invention, but these should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a catalytic cracking catalyst resistant to metal pollution, specifically The following steps are involved: (1) Coal-based kaolin that meets the particle size distribution requirements is first calcined, the calcined material is slurried with water, and a certain proportion of phosphoric acid and halloysite are added, stirred for a period of time, and the slurry enters the grinding equipment for processing; (2) adding Y-type molecular sieve and acidified alumina to the above-mentioned finely ground slurry in a certain proportion, stirring evenly, spraying granulation, and controlling the water content of the material at the outlet of the spray tower to be 15-18%; (3) The materials discharged from the tower pass through three tiltable drum granulation devices in sequence. Among them, the first device sprays a certain proportion of water-soluble rare earth salts, rare earth hydroxides or rare earth carbonates, the second device sprays a certain proportion of zinc dihydrogen phosphate dissolved in acetic acid, ammonia water or ammonium salts, and the third device sprays a certain proportion of triphenyl antimony. The rotation speed and spraying speed are controlled, and preliminary drying is accompanied by hot air; (4) The above materials continuously enter the roasting furnace with segmented temperature control to control the negative pressure in the furnace; (5) After calcination, the material is slurried in water, washed, filtered and dried to obtain a metal pollution-resistant catalyst.

2. The preparation method according to claim 1, Features: In step (1), the particle size distribution of coal-based kaolin is D50≤15μm, D90≤40μm, the roasting temperature is <900°C, and the phosphoric acid is added in a proportion of P 2 O 5 It accounts for 5-10wt% of the dry basis of coal-bearing kaolin, and the mass ratio of halloysite added to coal-bearing kaolin is (0.3-0.6):

1.

3. The preparation method according to claim 1, Features: In step (2), the pore volume of alumina is ≥ 0.55 ml / g, and EDTA is used for acidification in advance. 2 O 3 The mass ratio is 0.035-0.08, the proportion of alumina added is 5-15wt% of the final catalyst dry basis, and the proportion of Y-type molecular sieve added is 28-40wt% of the final catalyst dry basis.

4. The preparation method according to claim 1, Features: In step (3), the rare earth addition ratio is RE 2 O 3 The mass ratio of zinc dihydrogen phosphate added is (0.3-1.2)% of the final catalyst dry basis, the mass ratio of ZnO added is (0.05-0.15)% of the final catalyst dry basis, and the mass ratio of triphenyl antimony added is (0.05-0.20)% of the final catalyst dry basis.

5. The preparation method according to claim 1, Features: In step (4), the material temperature in the calcining furnace is 450-600°C.

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