CN109304212B

CN109304212B - Catalytic cracking catalyst and preparation method thereof

Info

Publication number: CN109304212B
Application number: CN201710632183.2A
Authority: CN
Inventors: 高雄厚; 潘志爽; 袁程远; 张海涛; 谭争国; 张忠东; 李雪礼; 段宏昌; 黄校亮; 任世宏; 郑云锋; 孙书红; 张君屹
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2017-07-28
Filing date: 2017-07-28
Publication date: 2021-09-28
Anticipated expiration: 2037-07-28
Also published as: CN109304212A

Abstract

The invention provides a catalytic cracking catalyst and a preparation method thereof, wherein the catalyst comprises 15-60wt% of molecular sieve, 15-60wt% of clay, 10-30wt% of pseudo-boehmite, 5-20wt% of binder, 0.1-5wt% of phosphorus-containing compound (calculated by P), 0.1-3wt% of magnesium-containing compound (calculated by Mg), and 0-5wt% of rare earth oxide. The preparation method comprises the following steps: (1) and (3) catalyst molding: mixing and pulping the molecular sieve, the clay, the pseudo-boehmite, the phosphorus-containing compound and the binder; then adding a magnesium-containing compound, mixing, pulping, heating, stirring, carrying out spray forming, and roasting to obtain a formed catalyst; (2) catalyst modification: mixing the formed catalyst, ammonium salt, phosphorus-containing compound and water, pulping, regulating pH value, heating to react, filtering and drying to obtain the catalytic cracking catalyst. The catalyst provided by the invention has the characteristics of low coke yield and high total liquid yield (the sum of liquefied gas, gasoline and diesel).

Description

Catalytic cracking catalyst and preparation method thereof

Technical Field

The invention relates to a catalytic cracking catalyst and a preparation method thereof, in particular to a phosphorus and magnesium modified catalytic cracking catalyst and a preparation method thereof.

Background

The Fluid Catalytic Cracking (FCC) technology is an important means for secondary processing of heavy oil due to relatively low investment, strong raw material adaptability and simple operation. With the gradual depletion of high-quality and light crude oil resources and the improvement of coking production capacity in the world, oil refining enterprises blend a large proportion of inferior crude oil, such as residual oil, coking wax oil, deasphalted oil and the like, in a catalytic cracking device for potential excavation and synergism. Due to poor cracking performance of the poor-quality raw oil, the carbon deposit amount on the FCC catalyst is increased, coke is adsorbed on the acid center of the catalyst and is not easy to desorb, and the heavy oil conversion capability and the product distribution of the catalyst are seriously influenced.

High heavy oil conversion and low coke yield are always the goals of catalytic cracker production for the petroleum refining industry. Catalytic cracking catalysts have been adapted to the above-mentioned objectives by modifying the properties of the matrix and molecular sieve.

CN1255530A, US5164073 adopt natural materials with larger pore volume, such as attapulgite, palygorskite, diatomite and the like as catalyst matrix materials; EP0550271a1, US5051385, US5997729 add a siliceous material, such as water glass, during the preparation of the aluminum-based catalyst to form amorphous large pore aluminum silicate to improve the heavy oil cracking ability.

Patent CN1436835A discloses a catalytic cracking catalyst and a preparation method thereof, wherein the catalyst contains 5-60% of mesoporous alumina, 5-60% of zeolite, 5-40% of binder and 5-85% of clay, the average pore diameter of the mesoporous alumina is not less than 3 nm, and the preparation method of the catalytic cracking catalyst is that the catalyst is prepared by uniformly mixing the zeolite, the mesoporous alumina, the binder and the clay, and then spraying, roasting, washing and drying the mixture. Compared with the conventional catalyst, the heavy oil conversion capability of the catalyst is enhanced, and the selectivity of gasoline and coke is obviously improved.

Patent CN106179458A provides a catalytic cracking catalyst, wherein the catalytic cracking catalyst contains 1-60% of cracking active component, 1-50% of mesoporous active material, 1-70% of clay and 1-70% of binder, based on the total weight of the catalytic cracking catalyst, and the mesoporous active material has a pseudo-boehmite crystal phase structure. The invention increases the content of mesopores in the catalytic cracking catalyst by matching the specific cracking active component, the specific mesoporous active material, the clay and the binder, and is beneficial to the diffusion and cracking of heavy oil macromolecules.

Patent CN101767029A discloses a heavy oil cracking catalyst and its application, said catalyst contains Y-type zeolite and modified rectorite, and its preparation method includes: mixing rectorite, an auxiliary agent, water and acid to obtain modified rectorite, then mixing the modified rectorite with Y-type zeolite, pulping, and spray-drying to obtain a catalyst; the auxiliary agent is selected from one or more of La, Co, Zn, Cu and Ti compounds, and the Y-type zeolite comprises modified ultrastable Y-type zeolite with the silicon-aluminum ratio of 6-15, the unit cell constant of 2.440-2.458nm and the proportion of the pore volume of secondary pores with the pore diameter of 80-1000 angstrom in the zeolite to the total secondary pore volume of 30-60%. The catalyst has strong heavy oil conversion capability and good coke selectivity.

In the composition of the FCC catalyst, the Y-type molecular sieve has a decisive influence on the comprehensive reaction performance of the catalyst, so that the modification of the Y-type molecular sieve is one of the most effective means for improving the reaction performance of the catalytic cracking catalyst. In recent years, the acidity of the molecular sieve is regulated and controlled at home and abroad to control the cracking reaction, reduce the condensation reaction of coke precursors and improve the coke selectivity of the catalyst.

EP 39183 pre-exchange NaY molecular sieves with ammonium sulfate to Na in zeolites₂O is 1 to 5% by weight, howeverThen mixing with phosphorus-containing compound, drying and roasting so as to obtain the invented phosphorus-containing ultrastable Y-type molecular sieve with improved cracking activity and gasoline selectivity.

CN1279130A discloses a method for preparing a phosphorus-modified ultrastable Y-type molecular sieve, which comprises the following steps of adding 0.5-5% of phosphorus and 0.5-6% of Na in percentage by weight of oxides₂O, P-NH having a cell constant of 2.460 to 2.475nm₄Carrying out hydrothermal roasting on the NaY molecular sieve for 0.5-4 hours at 450-700 ℃ in a roasting furnace in an atmosphere of 100% water vapor; carrying out liquid-phase aluminum extraction and silicon supplement reaction on the roasted product; then filtered and washed. The cracking catalyst containing the molecular sieve has high light oil yield, low coke yield and high heavy oil conversion capacity when being used for hydrocarbon cracking reaction.

CN103506153A discloses a catalytic cracking catalyst for reducing coke yield and producing gasoline, which comprises 10-50% of modified Y-type molecular sieve, no more than 30% of specific Y-type molecular sieve containing rare earth, 10-70% of clay and 10-40% of inorganic oxide binder calculated by oxide on a dry basis; the unit cell constant of the modified Y-type molecular sieve is 2.420-2440nm, and in percentage by weight, P is 0.05-6%, and RE is₂O₃0.03-10%, alumina less than 22%, and specific hydroxyl pit concentration less than 0.35 mmol/g. The catalytic cracking catalyst provided by the invention can reduce green coke and improve the utilization rate of heavy oil.

CN1624079A discloses a hydrocarbon cracking catalyst containing modified faujasite, wherein the modification method of zeolite is that firstly, the faujasite, a phosphorus compound and an ammonium compound are subjected to exchange reaction, the weight ratio of water to zeolite is 2-25, the pH value is 2.0-6.5, the temperature is 10-150 ℃, the exchange time is 0.l-4 hours, then, a rare earth solution is introduced into the exchange slurry, the reaction time is 1-60 minutes, the reaction is further carried out, and the catalyst is obtained by filtering and washing, roasting the phosphorus and rare earth modified zeolite for 0.l-3.5 hours at 250-800 ℃ under water vapor of l-100%. The modified zeolite prepared by the modification method has a unit cell constant of 2.440-2.465 nm, sodium oxide of 2.0-6.5 wt%, phosphorus content of 0.01-3 wt% and rare earth oxide of 0.1-15 wt%. The catalyst containing the molecular sieve has good activity stability, low coke yield, and strong heavy oil cracking capability and heavy metal pollution resistance.

CN101537366A reports a modified molecular sieve capable of improving coking performance, which is characterized in that the molecular sieve is obtained by a preparation method of a NaY molecular sieve through twice roasting, (1) the NaY molecular sieve is treated by phosphorus-containing ammonium solution exchange, and the treatment conditions are as follows: the system temperature is 40-100 ℃, the solution treatment time is 0.5-3 hours, the pH is 3.0-6.0, the weight ratio of the phosphorus-containing exchange solution to the molecular sieve is 3-20, the weight ratio of P/molecular sieve is 0.05-6.0%, and the solution is filtered and washed after exchange; (2) carrying out hydrothermal treatment at the temperature of 450-750 ℃ and roasting for 0.5-4 hours under 1-100% of water vapor; (3) with elements containing RE³⁺The ammonium solution exchange treatment of the sample after the first roasting is carried out, and the treatment conditions are as follows: the temperature of the system is 40-100 ℃, the solution treatment time is 0.5-3 hours, the pH value is 3.0-8.5, and the RE is contained³⁺The weight ratio of the exchange solution to the molecular sieve is 3-20, and RE is₂O₃The weight ratio of the molecular sieve/the molecular sieve is preferably 0.05-6.5%, and the mixture is filtered and washed after exchange; (4) and performing the second hydrothermal treatment under the same conditions as the conditions (2) in the first hydrothermal treatment. The molecular sieve has larger mesopore volume and larger macropore volume and good stability, and the heavy oil cracking capability is further improved while the coke yield of the catalyst is reduced.

CN102019195A discloses a catalytic cracking catalyst containing a modified Y molecular sieve, which contains 2-45 wt% of the modified Y molecular sieve, wherein the modified Y molecular sieve is obtained by carrying out exchange reaction on a Y-type molecular sieve and a rare earth solution, the weight ratio of water to the molecular sieve is 2-30, the pH value is 2.5-7.0, the temperature is 0-100 ℃, the exchange time is 0.1-3.5 hours, then a precursor of phosphorus is introduced into the exchange slurry, the reaction time is 1-70 minutes, and after filtering and washing, a filter cake is roasted for 0.5-6 hours at 180-650 ℃ under 5-100% of water vapor; the molecular sieve has a unit cell constant of 2.450-2.479 nm, sodium oxide of 2.0-6.0 wt%, phosphorus of 0.01-2.5 wt%, and rare earth oxide of 11-23 wt%. The catalyst containing the modified molecular sieve has strong heavy oil conversion capability and good coke selectivity.

Patent CN101284243A discloses a cracking catalyst comprising a rare earth ultrastable Y-type molecular sieve and a matrix, said matrix comprising a silica binder, said rare earth ultrastable Y-type molecular sieve being obtained by a process comprising the steps of: mixing the ultrastable Y-type zeolite and acid solution with equivalent concentration of 0.01N-2N according to the liquid-solid weight ratio of 4-20 at the temperature of 20-100 ℃, stirring for 10-300 min, washing, filtering, adding rare earth salt solution for rare earth ion exchange, washing, filtering and drying after exchange. The catalyst of the invention is used for heavy oil catalytic cracking, and has high conversion rate, high gasoline yield and low coke yield.

It can be seen from the above patents that the heavy oil conversion capability and coke selectivity of the catalyst can be improved by increasing the proportion of mesopores and macropores of the matrix material and increasing the diffusion rate of oil gas molecules, but the improvement range is limited; the modification of the molecular sieve is to introduce a single phosphorus element or a single magnesium element for modification. When the molecular sieve is modified by phosphorus-containing solution, phosphate is hydrolyzed to generate phosphoric acid, and the phosphoric acid cannot enter the small holes of the molecular sieve to react with the strong acid center in the pore channel due to the influence of the size and the space configuration of the phosphoric acid molecule [ Shenshihong, Panhuiwang, Xuchunsheng and the like ]. 86-99 ], the coke selectivity of the acid centers in the channels cannot be improved; the magnesium ions have small radius and can migrate into the pores of the molecular sieve. However, due to the diffusion resistance of the pore channels, the magnesium ions inevitably cover the outer surface of the molecular sieve and the acid centers in the large pore channels in the process of migrating to the pore channels, so that the acid content of the molecular sieve is reduced, and finally the heavy oil conversion capability is lost. Thus, the above patents do not address the contradiction between small pore coke selectivity and heavy oil conversion simultaneously.

Disclosure of Invention

The invention aims to provide a catalytic cracking catalyst with low coke yield, strong heavy oil conversion capability and high total liquid yield (the sum of liquefied gas, gasoline and diesel oil) and a preparation method thereof.

The invention provides a preparation method of a catalytic cracking catalyst, which comprises the following steps: (1) and (3) catalyst molding: mixing and pulping molecular sieve, clay, pseudo-boehmite, phosphorus-containing compound and binder for 30-180 minutes to obtain catalyst slurry, wherein rare earth compound and inorganic acid can be added into the catalyst slurry, and the adding sequence of the materials is not particularly limited; then adding a magnesium-containing compound, mixing and pulping, heating to 50-100 ℃, keeping the temperature constant for 30-90 minutes, carrying out spray forming, and roasting to obtain a formed catalyst; (2) catalyst modification: mixing and pulping the formed catalyst, ammonium salt, phosphorus-containing compound and water, and adding the formed catalyst (dry basis): ammonium salt: phosphorus-containing compound (in terms of phosphorus): adjusting pH to 3.0-5.0, heating to 60-100 deg.C, reacting for 30-90 min, filtering and drying to obtain the invented catalytic cracking catalyst.

The molecular sieve is one or more of NaY, NaX modified molecular sieves, such as REY, REX, REHY, USY and REUSY, and various Y-type molecular sieves, X-type molecular sieves, ZSM-type molecular sieves and beta molecular sieves with high silica-alumina ratio.

The clay of the invention is various clays which can be used as catalyst components, such as kaolin, bentonite, sepiolite, halloysite, montmorillonite and the like.

The pseudoboehmite of the invention can be one of boehmite, gibbsite and bayer stone or the combination thereof, and is preferably boehmite.

The phosphorus-containing compound is selected from one or more of orthophosphoric acid, phosphorous acid, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, aluminum phosphate and pyrophosphoric acid.

The binder is one or a mixture of silicon-aluminum gel, silicon-aluminum composite sol, aluminum sol, basic aluminum chloride and silica sol.

The rare earth compound is selected from one or more of rare earth chloride, rare earth nitrate, rare earth oxide and rare earth sulfate. Wherein the rare earth is preferably lanthanum and/or cerium.

The inorganic acid is selected from one or more of hydrochloric acid, nitric acid, phosphoric acid and sulfuric acid, and hydrochloric acid is preferred.

The magnesium-containing compound is selected from one or more of magnesium chloride, magnesium nitrate, magnesium hydroxychloride and magnesium sulfate, and preferably magnesium chloride.

The ammonium salt is selected from one or more of ammonium chloride, ammonium sulfate, ammonium bisulfate, ammonium nitrate, ammonium carbonate, ammonium bicarbonate, ammonium oxalate and ammonium phosphate.

The methods of the present invention can be performed by conventional methods, and specific methods are described in detail in patents CN98117896.0, CN02103907.0, and CN200610112685.4, which are incorporated herein by reference.

The invention provides a catalytic cracking catalyst, which contains molecular sieve, clay, pseudo-boehmite, a phosphorus-containing compound, a magnesium-containing compound and a binder. The catalyst comprises 15-60wt% of molecular sieve, 15-60wt% of clay, 10-30wt% of pseudo-boehmite, 5-20wt% of binder, 0.1-5wt% of phosphorus-containing compound (calculated as P), 0.1-3wt% of magnesium-containing compound (calculated as Mg) and 0-5wt% of rare earth oxide by mass of a dry basis of the catalyst.

According to the invention, a phosphorus-containing compound is introduced in the catalyst pulping process, and the phosphorus compound is firstly used for reacting with a molecular sieve in slurry and a strong acid center on the surface of an active matrix, so that the acid strength of the catalyst is weakened, the number of weak acid centers is increased, the contact probability of oil gas molecules and the acid centers on the surface of the catalyst is improved, the catalytic activity of the outer surface of the catalyst is improved, meanwhile, the acid strength of the outer surface is weakened, the adsorption capacity of the acid centers on the surface of the catalyst on the oil gas molecules is reduced, secondary reaction is inhibited, and coke formation is reduced; then adding magnesium compound for modification, because the strong acid on the outer surface of the catalyst and in the large pore channel is weakened by phosphorus, the adsorption effect on magnesium is weakened, and the diffusion of magnesium ions is accelerated, so that the magnesium ions are easier to migrate into the small pores of the catalyst to modulate the strong acid centers of the magnesium ions, the contact probability of the oil gas molecules outside the pores and the acid centers in the pore channels, which are influenced by the strong adsorption of the oil gas molecules in the pore channels of the catalyst, is reduced, the catalytic activity in the pore channels of the catalyst is improved, and the utilization rate of the active centers in the pore channels of the catalyst is improved; in the catalyst modification process, a phosphorus-containing compound and ammonium salt are added, so that the sodium content in the catalyst is reduced, the activity and the stability of the catalyst are improved, and the heavy oil conversion capacity of the catalyst is further improved; by the synergistic action of phosphorus and magnesium, acid centers inside and outside the pore channel of the catalyst can be fully utilized, and the heavy oil conversion capacity and coke selectivity of the catalyst are obviously improved, so that the total liquid yield (the sum of liquefied gas, gasoline and diesel oil) in the catalytic cracking process is improved.

Detailed Description

The following examples further illustrate the features of the present invention, but the scope of the present invention is not limited by these examples.

Evaluation methods used in (A) examples

Evaluation of catalytic cracking reaction selectivity: the catalyst cracking reaction selectivity evaluation was performed in a small Fixed Fluidized Bed (FFB) unit. The catalyst is treated for 10 hours at 800 ℃ under the condition of 100 percent of water vapor in advance. The properties of the reaction raw oil are shown in Table 1, the reaction temperature is 500-535 ℃, and the space velocity is 12-15 h^-1The solvent-oil ratio is 5.

TABLE 1 Properties of the stock oils

(II) production area and specification of raw materials used in examples

Kaolin: china kaolin company, kaolinite 86 wt%.

Halloysite: guangxi Nanning Sizheng mining Co., Ltd., halloysite 95 wt%.

Aluminum sol: catalyst works of Lanzhou petrochemical Co., Ltd., Al₂O₃The content was 24.56% by weight, and the Al/Cl molar ratio was 1.24.

USY zeolite, REHY zeolite, REY zeolite, DASY and ZSM-5 are all produced by catalyst factories of Lanzhou petrochemical company.

Pseudo-boehmite: 75.4 wt% of alumina, produced by Shandong alumina works.

Hydrochloric acid and nitric acid: and (4) industrial products.

Ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium carbonate, ammonium bicarbonate, ammonia water: and (4) industrial products.

Silica sol: SiO produced by the institute of chemical and physical university of Chinese academy of sciences₂The content was 27.0 wt%, and the pH was adjusted to 2.5 with hydrochloric acid.

Lanthanum chloride, cerium nitrate, diammonium phosphate, magnesium chloride, ammonium phosphate, magnesium nitrate, phosphoric acid, magnesium sulfate: pure analysis, and is produced in Beijing chemical plants.

Example 1

And (3) catalyst molding: 660g of pseudo-boehmite, 991g of kaolin, 540g of alumina sol, 990g of USY molecular sieve, 2431g of deionized water and 3g of diammonium hydrogen phosphate (calculated as phosphorus) are added into a reaction kettle, stirred for 60 minutes, added with 5.5 g of magnesium chloride (calculated as magnesium), mixed and pulped, heated to 60 ℃, mixed for 60 minutes, spray-molded, and roasted for 20 minutes at 500 ℃ to obtain the molded catalyst CD 1.

Catalyst modification: 2478 g of the above shaped catalyst CD1, 10 kg of water, 21 g of phosphoric acid (calculated as phosphorus) and 125 g of ammonium chloride were added to a reaction vessel, the pH was adjusted to 4.1, the temperature was raised to 90 ℃, stirring was carried out for 65 minutes, and the catalyst C1 of the present invention was obtained by filtration and drying.

Example 2

And (3) catalyst molding: 1.7 g of phosphoric acid (calculated by phosphorus), 1810g of molecular sieve, 190g of ZSM-5 and 5175g of deionized water are added into a reaction kettle and stirred for 10 minutes, then 464g of pseudo-boehmite, 593g of kaolin, 1744g of alumina sol and 67mL of hydrochloric acid are added, stirring is carried out for 180 minutes, 100g of magnesium nitrate (calculated by magnesium) is added and mixed, the temperature is raised to 100 ℃, stirring is carried out for 30 minutes, spray forming is carried out, and roasting is carried out at 600 ℃ for 60 minutes to obtain the formed catalyst CD 2.

Catalyst modification: 3397 g of the above shaped catalyst CD2, 10 kg of water, 1.8 g of ammonium phosphate (calculated as phosphorus) and 102 g of ammonium nitrate were added to a reaction kettle, the pH was adjusted to 3.1, the temperature was raised to 60 ℃, the mixture was stirred for 90 minutes, and the catalyst C2 of the present invention was obtained by filtration and drying.

Example 3

And (3) catalyst molding: 1333g of pseudo-boehmite, 728g of kaolin, 75g of ammonium phosphate (calculated by phosphorus), 1.7 g of phosphoric acid (calculated by phosphorus), 365g of halloysite, 353g of a Y molecular sieve, 358g of a G of a EHY molecular sieve, 352g of a DASY molecular sieve, 31g of ZSM-5, 5375g of deionized water and 1082g of alumina sol are added into a reaction kettle and stirred for 30 minutes, 0.2 g of magnesium sulfate (calculated by magnesium) and 0.15 g of magnesium chloride (calculated by magnesium) are added, the temperature is raised to 50 ℃, the stirring is carried out for 90 minutes, the spray forming is carried out, and the roasting is carried out at 400 ℃ for 90 minutes to obtain the formed catalyst CD 3.

Catalyst modification: 3430 g of the above-mentioned shaped catalyst CD3, 17 kg of water, 58g of ammonium phosphate (calculated as phosphorus), 42 g of phosphoric acid (calculated as phosphorus), 173 g of ammonium sulfate and 172 g of ammonium nitrate were added to a reaction vessel, the pH was adjusted to 4.9, the temperature was raised to 100 ℃, stirring was carried out for 30 minutes, and the catalyst C3 of the present invention was obtained by filtration and drying.

Example 4

And (3) catalyst molding: adding 9 g of ammonium phosphate (calculated by phosphorus), 275g of silica sol, 710g of DASY molecular sieve, 235 g of lanthanum chloride and 4270g of deionized pulp into a reaction kettle, pulping for 35 minutes, then adding 776g of pseudo-boehmite, 3255g of kaolin and 1005g of alumina sol, stirring for 10 minutes, adding 35 g of magnesium sulfate (calculated by magnesium), mixing and pulping, heating to 75 ℃, stirring for 70 minutes, spray-forming, and roasting for 80 minutes at 350 ℃ to obtain the formed catalyst CD 4.

Catalyst modification: 4736 g of the above-mentioned shaped catalyst CD4, 17 kg of water, 10g of ammonium hydrogen phosphate (calculated as phosphorus) and 189 g of ammonium nitrate were added to a reaction kettle, the pH was adjusted to 3.5, the temperature was raised to 80 ℃, the mixture was stirred for 40 minutes, and the catalyst C4 of the present invention was obtained by filtration and drying.

Example 5

And (3) catalyst molding: adding 12 g of diammonium hydrogen phosphate (calculated by phosphorus), 987g of DASY molecular sieve, 71g of cerium nitrate and 5124g of deionized water into a reaction kettle, pulping for 35 minutes, then adding 877g of pseudo-boehmite, stirring for 15 minutes, adding 1127g of kaolin and 2600g of alumina sol, pulping for 20 minutes, adding 74 g of magnesium nitrate (calculated by magnesium), pulping, heating to 71 ℃, stirring for 60 minutes, spray-forming, and roasting at 400 ℃ for 55 minutes to obtain the formed catalyst CD 5.

Catalyst modification: 3351 g of the above-mentioned shaped catalyst CD5, 15 kg of water, 31g of ammonium hydrogen phosphate (calculated as phosphorus) and 107 g of ammonium chloride were added to a reaction vessel, the pH was adjusted to 4.3, the temperature was raised to 67 ℃, stirring was carried out for 55 minutes, and the catalyst C5 of the present invention was obtained by filtration and drying.

Example 6

And (3) catalyst molding: 1150g of EY, 300g of DASY molecular sieve and 2100g of deionized water are added into a reaction kettle to be mixed and pulped, then 16 g of ammonium phosphate (calculated by phosphorus) and 13 g of phosphoric acid (calculated by phosphorus) are added, stirred for 23 minutes, 1091g of pseudo-boehmite, 911g of kaolin and 771g of alumina sol are added, stirred for 40 minutes, 5g of magnesium chloride (calculated by magnesium) is added, the temperature is raised to 60 ℃, stirred for 40 minutes, spray forming is carried out, and roasting is carried out at 500 ℃ for 35 minutes to obtain the formed catalyst CD 6.

Catalyst modification: 3278 g of the above-mentioned shaped catalyst CD6, 15 kg of water, 44g of ammonium dihydrogen phosphate (calculated as phosphorus) and 78 g of ammonium sulfate were added into a reaction vessel, the pH was adjusted to 3.7, the temperature was raised to 58 ℃, stirring was carried out for 64 minutes, and the catalyst C6 of the present invention was obtained by filtration and drying.

Comparative example 1

Prepared according to the method provided by patent CN 101284243A:

adding 990g USY molecular sieve (dry basis) into 10L 0.2N oxalic acid aqueous solution, stirring to mix uniformly, heating to 95 ℃ for 1 hour, filtering, washing with water, taking out filter cake, placing in 2L decationized water, adding 71.2 g rare earth solution, stirring, heating to 92 ℃ for 1 hour, filtering, washing, and drying the filter cake at 120 ℃ to obtain a rare earth ultrastable Y-type zeolite sample marked as A.

Preparing silica sol: 1 liter of water glass solution with the silica concentration of 155g/l and 1 liter of diluted aluminum sulfate solution (the free acid concentration of 148g/l and the alumina content of 20g/l) are simultaneously introduced into a rapid mixer for reaction, and silica sol is obtained.

Preparation of kaolin and silica sol slurry: 991g of kaolin was added to the silica sol prepared above, and slurried for 1 hour to obtain kaolin and silica sol slurry.

Preparing a mixed slurry of pseudo-boehmite and a molecular sieve: 660g of pseudo-boehmite and 1320 g of deionized water are mixed and pulped for 30 minutes, then 25 ml of hydrochloric acid is added and pulped for 2 hours, then 990g of A molecular sieve slurry is added and pulped for 30 minutes, and mixed slurry of the pseudo-boehmite and the molecular sieve is obtained.

Preparation of the catalyst: mixing the prepared kaolin and silica sol slurry with the prepared mixed slurry of the pseudo-boehmite and the molecular sieve, pulping for 10 minutes to obtain catalyst slurry, then carrying out spray drying and molding on the obtained slurry at the temperature of 180 ℃ to obtain solid particles with the diameter of 20-120 microns, washing the solid particles with deionized water until no sodium ion is detected, filtering, and drying at the temperature of 150 ℃ to obtain the catalyst D1.

Comparative example 2

And (3) catalyst molding: 660g of pseudo-boehmite, 991g of kaolin, 540g of alumina sol, 990g of USY molecular sieve, 2431g of deionized water, 3g of diammonium hydrogen phosphate (calculated as phosphorus) and 5.5 g of magnesium chloride (calculated as magnesium) are added into a reaction kettle to be mixed and pulped, stirred for 60 minutes, heated to 60 ℃, stirred for 60 minutes, spray-molded, and roasted for 20 minutes at 500 ℃ to obtain the molded catalyst DD 2.

Catalyst modification: 2478 g of the above shaped catalyst DD2, 10 kg of water, 21 g of phosphoric acid (calculated as phosphorus) and 125 g of ammonium chloride were added to a reaction kettle, the pH was adjusted to 4.1, the temperature was raised to 90 ℃, stirring was carried out for 65 minutes, and the catalyst D2 of the present invention was obtained by filtration and drying.

Comparative example 3

And (3) catalyst molding: 660g of pseudo-boehmite, 991g of kaolin, 540g of alumina sol, 990g of USY molecular sieve, 2431g of deionized water and 5.5 g of magnesium chloride (calculated as magnesium) are added into a reaction kettle, stirred for 60 minutes, added with 3g of diammonium hydrogen phosphate (calculated as phosphorus), mixed and pulped, heated to 60 ℃, mixed for 60 minutes, spray-molded, and roasted for 20 minutes at 500 ℃ to obtain the molded catalyst DD 3.

Catalyst modification: 2478 g of the above shaped catalyst DD3, 10 kg of water, 21 g of phosphoric acid (calculated as phosphorus) and 125 g of ammonium chloride were added to a reaction kettle, the pH was adjusted to 4.1, the temperature was raised to 90 ℃, stirring was carried out for 65 minutes, and the catalyst D3 of the present invention was obtained by filtration and drying.

The results of evaluating the reaction properties of the catalysts prepared in examples 1 to 6 and comparative examples 1 to 3 are shown in Table 2.

TABLE 2 catalyst fixed bed evaluation results

Catalyst and process for preparing same	C1	C2	C3	C4	C5	C6	D1	D2	D3
										Dry gas	3.39	3.45	3.34	3.21	3.17	3.06	3.45	3.34	3.19
Liquefied gas	13.67	13.66	13.43	14.79	13.51	14.66	13.78	13.72	12.82
										Gasoline (gasoline)	43.11	43.78	42.82	41.7	43.07	42.18	42.14	41.61	39.34
Diesel oil	27.52	26.76	27.92	27.79	27.99	27.87	27.52	28	25.4
										Heavy oil	5.13	5.11	5.45	5.71	5.37	5.49	6.02	6.24	12.33
Coke	7.18	7.24	7.04	6.8	6.89	6.74	7.09	7.09	6.92
										Conversion rate	67.35	68.13	66.63	66.5	66.64	66.64	66.46	65.76	62.27
Total liquid yield	84.3	84.2	84.17	84.28	84.57	84.71	83.44	83.33	77.56

From the fixed bed evaluation results, it can be seen that the catalyst prepared from the molecular sieve modified by the method of the present invention has excellent heavy oil conversion capability and good coke selectivity. The catalysts of comparative examples D2 and D3, which were modified, had reduced heavy oil conversion ability due to the fact that when phosphorus and magnesium were introduced simultaneously or after magnesium was introduced first during the catalyst modification, magnesium ions had a small radius and low diffusion resistance and reacted preferentially with the acid sites of the catalyst to cover a portion of the acid sites, resulting in a decrease in the total acid content of the catalyst and a decrease in the cracking performance of the catalyst. The catalyst prepared by the process of the present invention has more excellent coke selectivity and higher total liquid yield with increased conversion and reduced heavy oil compared to the catalyst of comparative example 1 (D1).

The present invention is capable of other embodiments, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for preparing a catalytic cracking catalyst, the method comprising: (1) and (3) catalyst molding: mixing and pulping the molecular sieve, the clay, the pseudo-boehmite, the phosphorus-containing compound and the binder for 30-180 minutes to obtain catalyst slurry; then adding a magnesium-containing compound, mixing and pulping, heating to 50-100 ℃, keeping the temperature constant for 30-90 minutes, carrying out spray forming, and roasting to obtain a formed catalyst; (2) catalyst modification: mixing and pulping the formed catalyst, ammonium salt, phosphorus-containing compound and water, and adding the dry-based formed catalyst in the proportion: ammonium salt: phosphorus-containing compounds in terms of phosphorus: water =1:0.03-0.1:0.0005-0.03:3-5, pH is adjusted to 3.0-5.0, temperature is raised to 60-100 ℃, reaction is carried out for 30-90 minutes, and the catalytic cracking catalyst is prepared by filtering and drying.

2. The method according to claim 1, wherein a rare earth compound and an inorganic acid are added to the catalyst slurry in the step (1).

3. The preparation method according to claim 1, wherein the molecular sieve is NaY or NaX modified molecular sieve, and the modified molecular sieve is selected from one or more of REY, REX, REHY, USY and REUSY.

4. The preparation method according to claim 1, wherein the clay is one or more of kaolin, bentonite, sepiolite, halloysite and montmorillonite.

5. The method of claim 1, wherein the pseudoboehmite is one of boehmite, bayerite, or a combination thereof.

6. The method according to any one of claims 1 to 5, wherein the pseudoboehmite is boehmite.

7. The method according to claim 1, wherein the phosphorus-containing compound is one or more selected from orthophosphoric acid, phosphorous acid, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, aluminum phosphate and pyrophosphoric acid.

8. The preparation method according to claim 1, wherein the binder is one of a silicon-aluminum gel, a silicon-aluminum composite sol, an aluminum sol, basic aluminum chloride and a silicon sol or a mixture thereof.

9. The preparation method according to claim 2, wherein the rare earth compound is one or more selected from the group consisting of rare earth chloride, rare earth nitrate, rare earth oxide and rare earth sulfate.

10. The method according to claim 2 or 9, wherein the rare earth is lanthanum and/or cerium.

11. The method according to claim 2, wherein the inorganic acid is selected from one or more of hydrochloric acid, nitric acid, phosphoric acid, and sulfuric acid.

12. The method according to claim 2 or 11, wherein the inorganic acid is hydrochloric acid.

13. The preparation method according to claim 1, wherein the magnesium-containing compound is one or more selected from the group consisting of magnesium chloride, magnesium nitrate, magnesium hydroxychloride and magnesium sulfate.

14. The method according to claim 1 or 13, wherein the magnesium-containing compound is magnesium chloride.

15. The method according to claim 1, wherein the ammonium salt is selected from one or more of ammonium chloride, ammonium sulfate, ammonium bisulfate, ammonium nitrate, ammonium carbonate, ammonium bicarbonate, ammonium oxalate and ammonium phosphate.

16. A catalytic cracking catalyst prepared by the preparation method of claim 1 or 2, wherein the catalytic cracking catalyst contains a molecular sieve, clay, pseudoboehmite, a phosphorus-containing compound, a magnesium-containing compound, and a binder; the catalyst comprises 15-60wt% of molecular sieve, 15-60wt% of clay, 10-30wt% of pseudo-boehmite, 5-20wt% of binder, 0.1-5wt% of phosphorus-containing compound calculated by P, and 0.1-3wt% of magnesium-containing compound calculated by Mg.

17. The catalyst of claim 16 wherein the rare earth oxide is included in the catalyst in an amount of 0 to 5 wt%.