CN113058636B - Catalytic cracking catalyst and preparation method thereof - Google Patents

Catalytic cracking catalyst and preparation method thereof Download PDF

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CN113058636B
CN113058636B CN202110353423.1A CN202110353423A CN113058636B CN 113058636 B CN113058636 B CN 113058636B CN 202110353423 A CN202110353423 A CN 202110353423A CN 113058636 B CN113058636 B CN 113058636B
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molecular sieve
mesoporous
kaolin
macroporous
microporous
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CN113058636A (en
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鲍晓军
曹弘
王廷海
王鹏照
岳源源
崔勍焱
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Fuzhou University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/005—Mixtures of molecular sieves comprising at least one molecular sieve which is not an aluminosilicate zeolite, e.g. from groups B01J29/03 - B01J29/049 or B01J29/82 - B01J29/89
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/61—Surface area
    • B01J35/615—100-500 m2/g
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/64—Pore diameter
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G11/00—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
    • C10G11/02—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils characterised by the catalyst used
    • C10G11/04—Oxides
    • C10G11/05—Crystalline alumino-silicates, e.g. molecular sieves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/30—After treatment, characterised by the means used
    • B01J2229/42—Addition of matrix or binder particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
    • B01J29/0308—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
    • B01J29/7007—Zeolite Beta

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  • Oil, Petroleum & Natural Gas (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
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Abstract

The invention relates to a catalytic cracking catalyst and a preparation method thereof. The catalyst has the characteristics of step pore distribution of micropore-mesopore and macropore, wherein the macroporous structure is provided by modified kaolin, the mesoporous structure is provided by SBA-15, MCM-41, MCM-22 and the like, and the microporous structure is provided by molecular sieves such as ZSM-5, Beta and the like. The assembling method comprises the steps of firstly assembling a molecular sieve with a mesoporous structure into a macroporous channel of kaolin under the condition of ball milling crystallization, and then assembling a molecular sieve with a microporous structure into mesoporous and macroporous channels by ball milling. Finally, the catalytic cracking catalyst is obtained after spray granulation, and the catalyst shows higher residual oil conversion rate and light oil yield when being used in residual oil catalytic cracking reaction, and is particularly suitable for overweight residual oil raw materials.

Description

Catalytic cracking catalyst and preparation method thereof
Technical Field
The invention belongs to the field of oil refining catalysis, and particularly relates to a catalytic cracking catalyst and a preparation method thereof.
Background
With the continuous improvement of the heavy degree of crude oil, the catalytic cracking process for converting macromolecular residual oil into propylene, liquefied gas, gasoline and diesel oil is more and more important in the position of oil refining catalyst enterprises, the catalytic cracking process is that under the action of an acid catalyst, macromolecular residual oil is firstly pre-cracked in a macroporous or mesoporous matrix into a product of medium molecules, and the product of medium molecules is finally cracked in a pore passage of a microporous molecular sieve into components such as micromolecular gasoline and diesel oil, so that the development of a catalyst containing micropores and mesoporous structures is the core for promoting the technical progress of a catalytic cracking device. At present, the catalytic cracking catalyst is prepared by taking a microporous molecular sieve as an active component, taking kaolin as a matrix and taking pseudo-boehmite as a binder. The hierarchical pore molecular sieve material and the micro-mesoporous composite carrier material are ideal carriers of the heavy oil catalytic cracking catalyst because the hierarchical pore molecular sieve material and the micro-mesoporous composite carrier material simultaneously have a strong acid microporous structure and a mesoporous pore canal with small mass transfer resistance. Bao et al (Bao X., et al, Journal of catalysis. 2007251 (1): 69-79) report a method of preparing a catalytic cracking catalyst. The catalyst is a hierarchical pore structure catalyst with macropores, mesopores and mesopores, which is obtained by adopting hexadecyl trimethyl ammonium bromide as a template agent and assembling a precursor of a Y-shaped molecular sieve on kaolin microspheres in situ. CN201110101161.6 discloses a heavy oil catalytic cracking catalyst compounded by a micro-mesoporous molecular sieve and a preparation method thereof, wherein the preparation process of the catalyst is to add a micro-mesoporous molecular sieve precursor into a synthesis system of the mesoporous molecular sieve, and realize the compounding of the micro-mesoporous molecular sieve under the crystallization condition of the mesoporous molecular sieve. CN201910547779.1 discloses a preparation method of a catalyst for improving the slag mixing proportion of catalytic cracking coker gas oil. The catalyst is prepared by firstly adopting a spray granulation method to obtain a catalyst matrix, then adding a matrix material into a NaY molecular sieve synthesis system, and growing a layer of NaY molecular sieve on the surface of the matrix in situ to obtain the catalytic cracking catalyst simultaneously containing micropores and mesoporous structures. The preparation of the catalytic cracking catalyst takes the reduction of the length of micropores in the microporous molecular sieve as a means to reduce the mass transfer resistance of the catalyst. However, the step pore molecular sieve prepared by the prior art has the defects of high synthesis cost, poor mesoporous connectivity and order degree and the like, and has very limited improvement degree on the catalyst diffusion performance. The micro-mesoporous composite carrier material based on the nano assembly technology is difficult to realize the in-situ controllable growth of the microporous molecular sieve on the surface of the mesoporous molecular sieve, and the prepared composite carrier is usually only the simple composition of the microporous molecular sieve and the mesoporous molecular sieve in the physical degree, and even the phenomena of two-phase separation and independent growth can occur.
The invention provides a catalytic cracking catalyst and a preparation method thereof, and the catalytic cracking catalyst with a micropore-mesopore-macropore structure is obtained by firstly assembling a mesopore molecular sieve into the interior of a macropore kaolin matrix pore channel under the condition of ball milling crystallization, then assembling a micropore molecular sieve into mesopore and macropore kaolin matrix under the condition of ball milling, and finally carrying out spray granulation. The catalyst prepared by the method has the advantages of high assembly efficiency, adjustable assembly proportion and the like, so that the communication among micropores, mesopores and macropores is better, and the catalyst can show better residual oil conversion rate and light oil yield when being used for catalytic cracking reaction.
Disclosure of Invention
The invention discloses a catalytic cracking catalyst and a preparation method thereof, wherein the preparation method of the catalyst comprises the following steps:
(1) preparation of macroporous kaolin solid: roasting kaolin at 650-900 ℃, then heating a hydrochloric acid solution with the concentration of 1-6 mol/L to 50-90 ℃, adding a certain amount of kaolin into the acid solution according to the mass ratio of the acid solution to the kaolin of 3-10:1, stirring for 1-8 h, and finally filtering, washing and drying to obtain acidic macroporous kaolin solid;
(2) preparation of mesoporous molecular sieve slurry: mixing a silicon source, an aluminum source, a template agent and deionized water, adjusting the pH value to 10-13, pre-crystallizing at the temperature of 70-150 ℃ for 3-9 h, crystallizing at the temperature of 160-220 ℃ for 4-20 h, and cooling to obtain mesoporous molecular sieve slurry; wherein the mesoporous molecular sieve is an SBA-15, SBA-16, MCM-41 or MCM-22 molecular sieve;
(3) adding the macroporous kaolin solid into the mesoporous molecular sieve slurry, adjusting the pH, completing the purification process under the condition of ball milling crystallization, and filtering to obtain a mesoporous-macroporous composite acidic material;
(4) synthesizing microporous molecular sieve nanocrystalline precursor slurry: fully mixing a silicon source, an aluminum source, a template agent or a phosphorus source and deionized water under the stirring condition, adjusting the pH value to 10-13, adding the mixture into a crystallization kettle, then pre-crystallizing the mixture for 4-8 h at the temperature of 80-100 ℃, crystallizing the mixture for 4-12 h at the temperature of 160-180 ℃, and cooling the crystallized mixture to obtain microporous molecular sieve nanocrystal precursor slurry, wherein the microporous molecular sieve comprises one or more of ZSM-5, Beta, SAPO-11, SAPO-34, Y and mordenite;
(5) adding the mesoporous-macroporous composite acidic material in the step (3) into the step (4), adjusting the pH, completing the rest crystallization process under the condition of ball milling, and filtering, washing, exchanging and drying to obtain an acidic material with a microporous-mesoporous-macroporous structure;
(6) the pseudo-boehmite, the hydrochloric acid, the water and the acid material with the micropore-mesopore-macropore structure are pulped, and the catalytic cracking catalyst is obtained after spray granulation, drying and roasting.
Preferably, the microporous molecular sieve is ZSM-5 molecular sieve, SiO 2 :Al 2 O 3 In the molecular ratio of 25-300: 1 range, SiO in Beta molecular sieve 2 :Al 2 O 3 In the molecular ratio of 25-100: 1 range, Y type molecular sieve SiO 2 :Al 2 O 3 In the molecular ratio of 5.0-7.3: mordenite molecular sieve SiO within 1 range 2 :Al 2 O 3 In a molecular ratio of 5-20: 1, the phosphorus-aluminum ratio of the SAPO-11 molecular sieve is between 0.6 and 1.0: 1 in the range of.
Preferably, the mesoporous molecular sieve is pure silicon or aluminum-containing, SiO 2 :Al 2 O 3 In the range of 5 to 500.
Preferably, the silicon source used by the mesoporous molecular sieve is one or more of water glass, ethyl orthosilicate or silica gel powder, and the aluminum source is sodium metaaluminate, aluminum sulfate or aluminum nitrate.
Preferably, in the step (3), the pH value is 10-12.5, the crystallization temperature is 160-180 ℃, the crystallization time is 10-80 h, and the crystallization condition of the mesoporous molecular sieve is adopted.
Preferably, in the step (5), the pH value is 10-12.5, the crystallization temperature is 160-180 ℃, the crystallization time is 10-120 h, and the crystallization condition of the microporous molecular sieve is adopted.
Preferably, the ball milling speed is 200-1000 r/min.
Preferably, in the step (6), the mass ratio of the acidic material with the micropore-mesopore-macropore structure, the pseudo-boehmite, the water and the hydrochloric acid is 30-40: 50-60: 400-450: 3-5.
The catalytic cracking catalyst containing the micropore-mesopore-macropore structure comprises the following components: the composite material comprises a microporous molecular sieve, a mesoporous molecular sieve, macroporous kaolin and alumina, wherein the content of the microporous molecular sieve is 5-35 wt% calculated by weight, the content of the mesoporous molecular sieve is 5-35 wt% calculated by weight, the content of the macroporous kaolin is 5-40 wt% calculated by weight, the content of the alumina is 30-60 wt% calculated by weight, and the sum of the mass percentages of the components is 100%.
The invention has the following advantages:
compared with the existing catalyst, the active component in the catalyst provided by the invention is to assemble a mesoporous molecular sieve into the pore canal of a macroporous kaolin matrix, then assemble a microporous molecular sieve into the mesoporous and macroporous kaolin matrices under the condition of ball milling, and finally obtain the catalytic cracking catalyst with a microporous-mesoporous-macroporous structure through spray granulation. Because a ball milling method is introduced in the crystallization process, shearing force generated by high-speed impact of the grinding balls can generate more growth sites on the surface of the kaolin, meanwhile, the mesoporous molecular sieve nanocrystals can more easily enter the kaolin pore channels to grow under the ball milling condition, and the assembled mesoporous molecular sieve has lower mass transfer resistance. Similarly, under the condition of ball milling, the microporous molecular sieve is easier to assemble into the mesoporous and macroporous kaolin matrixes, and the problem that most microporous molecular sieves independently grow in the existing assembly method is solved. When the catalyst is used for preparing a catalytic cracking catalyst, the generated gasoline or diesel intermediate component is easier to diffuse to a bulk phase from the inside of a catalyst pore channel due to lower mass transfer resistance, and the secondary cracking reaction of the gasoline or diesel is prevented. Therefore, the catalytic cracking catalyst prepared by the invention has higher yield of gasoline and diesel oil.
The rotating speed of the ball milling process is one of key factors influencing the assembly effect, the faster the ball milling rotating speed is, the higher the collision probability between the microporous molecular sieve and the mesoporous molecular sieve is, and the larger the collision force and the shearing force are, but when the ball milling rotating speed is too high, the collapse of the structure of the mesoporous molecular sieve is easily caused, and the control of the ball milling rotating speed in a certain range is an important parameter for realizing high-efficiency assembly.
Drawings
Fig. 1 is a representation of nitrogen adsorption-desorption, (a) is a nitrogen adsorption-desorption curve, and (b) is a pore size distribution of a sample. (a) For nitrogen adsorption-desorption curves, at P/P 0 Compared with a D-1 sample without ball milling, the C-3 sample shows higher mesoporous adsorption capacity, and the mesoporous hysteresis ring is obviously reduced, which is mainly benefited by the novel ball milling crystallization method, so that more mesoporous SBA-15 is assembled in a macroporous channel of kaolin, and the connectivity of the channel is improved, and the mass transfer resistance is reduced. (b) For the pore size distribution of the sample, the D-1 sample obtained without adding the ball mill has an obvious SBA-15 mesoporous structure near 8-9 nm, and the ball-milled sample C-3 has a more dispersed pore size distribution near 10 nm, i.e. the microporous structure is more than that of the D-1 sample without adding the ball mill, which also fully explains the good assembling property of the ball-milled sample C-3. The assembly efficiency of the D-1 sample was low and a considerable portion of SBA-15 grew independently.
Detailed Description
The preparation process of the catalytic cracking catalyst comprises four steps: (1) preparing a macroporous kaolin matrix; (2) assembling the mesoporous molecular sieve into a macroporous kaolin matrix pore channel; (3) assembling the microporous molecular sieve into mesoporous and macroporous kaolin pore channels; (4) and spray granulating to obtain the final catalytic cracking catalyst.
Example 1
(1) And (3) preparing a macroporous kaolin solid. Activating kaolin for 4 hours at 850 ℃, then adding the kaolin into 5 mol/L hydrochloric acid solution, stirring uniformly, wherein the dosage of the hydrochloric acid solution is 5 times of the mass of the kaolin, heating to 65 ℃, and continuing stirring for 4 hours. Filtering, washing and drying to obtain modified macroporous kaolin;
(2) and (3) preparing mesoporous SBA-15 molecular sieve precursor slurry. Under the condition of 40 ℃, 20 g of triblock copolymer P123, 40 g of hexadecyl trimethyl ammonium bromide, 450 mL of 2 mol/L hydrochloric acid and 300 mL of deionized water are mixed until the mixture is uniformly stirred; then adding 42.8 g of tetraethoxysilane, continuously stirring for 24 hours, adjusting the pH value to 11, and adding into a reaction kettle for pre-crystallization for 8 hours at the temperature of 100 ℃; finally, carrying out hydrothermal crystallization for 20 h at 160 ℃ to ensure that the precursor is well shaped, and taking out and cooling to obtain SBA-15 molecular sieve precursor slurry.
(3) And (3) assembling the mesoporous SBA-15 with macroporous Kaolin (named as SBA-15/Kaolin). Adding 30g of modified macroporous Kaolin into SBA-15 precursor slurry, uniformly stirring, adjusting the pH value to 11, adding the mixture into a ball mill, raising the temperature to 160 ℃, carrying out ball milling crystallization for 50 hours at the rotating speed of 700 RPM (revolution per minute), assembling mesoporous SBA-15 and macroporous Kaolin under the condition, filtering, washing and drying to obtain SBA-15/Kaolin.
(4) And (3) preparing the microporous ZSM-5 molecular sieve nanocrystalline slurry. Mixing 40% silica sol and Al 2 (SO 4 ) 3 NaOH, tetrapropylammonium hydroxide (TPAOH) and deionized water as n (Na) 2 O) : n(Al 2 O 3 ) : n(SiO 2 ) :n(TPAOH) n(H 2 O) = 28:2:100:5:4000, uniformly mixing, adjusting the pH value to 11, adding the mixture into a reaction kettle, pre-crystallizing for 8 hours at the temperature of 100 ℃, carrying out hydrothermal crystallization for 12 hours at the temperature of 180 ℃ to ensure that the microporous ZSM-5 molecular sieve is well shaped, and cooling to obtain the microporous ZSM-5 molecular sieve nanocrystalline slurry.
(5) Uniformly mixing 20 g of microporous ZSM-5 molecular sieve nanocrystal slurry and 20 g of SBA-15/Kaolin, adjusting the pH value to 11, adding the mixture into a ball mill, heating to 180 ℃, carrying out ball milling crystallization for 30 hours at the rotation speed of 700 RPM (revolution speed), assembling the microporous ZSM-5 molecular sieve nanocrystal and the SBA-15/Kaolin under the condition, and filtering, washing, exchanging and drying to obtain the ZSM-5/SBA-15/Kaolin composite acidic material.
(6) ZSM-5/SBA-15/Kaolin, pseudoboehmite, water and hydrochloric acid were mixed according to a 40: 60: 400: 3, pulping, then carrying out spray granulation, drying and roasting at 500 ℃ to obtain the final catalytic cracking catalyst, wherein the final catalyst comprises the following components in percentage by mass: ZSM-5 molecular sieve: kaolin: SBA-15 molecular sieve: alumina =20:8.24:11.76: 60. The catalyst was named C-1.
Example 2
The same procedure and method as in example 1 except that 30g of the modified macroporous kaolin in step (3) was changed to 60 g. The final product name is C-2. The final catalyst had the following composition by mass: ZSM-5 molecular sieve: kaolin: SBA-15 molecular sieve: alumina =20:11.67:8.33: 60.
Example 3
The same synthetic procedure and method as in example 1 except that 20 g of the microporous ZSM-5 molecular sieve in step (5) was changed to 30 g. The final product name is C-3. The final catalyst had the following composition by mass: ZSM-5 molecular sieve: kaolin: SBA-15 molecular sieve: alumina =24:6.59:9.1: 60.
Example 4
The same synthetic procedure and method as in example 1 were followed except that the final ball milling rotation speed in steps (3) and (5) was changed from 700 r/min to 400 r/min. The product name is C-4. The final catalyst had the following composition by mass: ZSM-5 molecular sieve: kaolin: SBA-15 molecular sieve: alumina =20:8.24:11.76: 60.
Example 5
The same synthetic procedure and method as in example 1, except that the microporous ZSM-5 molecular sieve in step (4) was changed to a microporous Beta molecular sieve. Uniformly stirring 0.49 g of aluminum isopropoxide, 24.6 g of deionized water, 9.57 g of tetraethylammonium hydroxide (35 percent) and 13.15 g of tetraethoxysilane, adjusting the pH value of the slurry to 11.8, and continuously stirring for 6 hours to obtain initial sol-gel slurry, wherein the molar ratio of the components of the slurry to Al is 18TEAOH to Al 2 O 3 :50SiO 2 :1000H 2 And O. And transferring the slurry into a polytetrafluoroethylene reaction kettle, and carrying out hydrothermal crystallization for 20 h at the temperature of 130 ℃ to obtain a final Beta molecular sieve nanocrystal precursor. And (3) changing the microporous molecular sieve in the step (5) into a Beta molecular sieve to obtain Beta/SBA-15/Kaolin, and obtaining the final catalytic cracking catalyst after the step (6), wherein the product name is C-5. The final catalyst had the following composition by mass: beta molecular sieve: kaolin: SBA-15 molecular sieve: alumina =20:8.24:11.76: 60.
Comparative example 1 (without crystallization by ball milling)
(1) And (3) preparing macroporous kaolin solid. Activating kaolin for 4 hours at 850 ℃, then adding the kaolin into 5 mol/L hydrochloric acid solution, stirring uniformly, wherein the dosage of the hydrochloric acid solution is 5 times of the mass of the kaolin, heating to 65 ℃, and continuing stirring for 4 hours. Filtering, washing and drying to obtain modified macroporous kaolin;
(2) and (3) preparing mesoporous SBA-15 molecular sieve precursor slurry. Under the condition of 40 ℃, 20 g of triblock copolymer P123, 40 g of hexadecyl trimethyl ammonium bromide, 450 mL of 2 mol/L hydrochloric acid and 300 mL of deionized water are mixed until the mixture is uniformly stirred; then 42.8 g of tetraethoxysilane is added and stirred continuously for 24 hours; and finally, adding the precursor into a stainless steel reaction kettle with a polytetrafluoroethylene lining, performing hydrothermal crystallization for 20 hours at the temperature of 100 ℃ to well shape the precursor, taking out the precursor, and cooling to obtain SBA-15 molecular sieve precursor slurry.
(3) Assembly of mesoporous SBA-15 with macroporous Kaolin (named SBA-15/Kaolin). Adding 30g of modified macroporous Kaolin into SBA-15 precursor slurry, uniformly stirring, adding the mixed slurry into a stainless steel reaction kettle with a polytetrafluoroethylene lining, performing hydrothermal crystallization for 50 hours at 100 ℃, and filtering, washing and drying to obtain SBA-15/Kaolin.
(4) And (3) preparing the microporous ZSM-5 molecular sieve nanocrystalline slurry. Mixing 40% silica sol and Al 2 (SO 4 ) 3 NaOH, tetrapropylammonium hydroxide (TPAOH) and deionized water as n (Na) 2 O) : n(Al 2 O 3 ) : n(SiO 2 ) :n(TPAOH) n(H 2 O) = 28:2:100:5:4000, uniformly mixing, performing hydrothermal crystallization for 12 hours at 180 ℃ to ensure that the microporous ZSM-5 molecular sieve is well shaped, and cooling to obtain microporous ZSM-5 molecular sieve nano-crystalline slurry.
(5) Adding 20 g of microporous ZSM-5 molecular sieve nano crystal slurry and 20 g of SBA-15/Kaolin into a stainless steel reaction kettle with a polytetrafluoroethylene lining, carrying out hydrothermal crystallization for 30 h at 180 ℃, and filtering, washing and drying to obtain the ZSM-5/SBA-15/Kaolin composite acidic material.
(6) ZSM-5/SBA-15/Kaolin, pseudo-boehmite, water and hydrochloric acid are mixed according to the ratio of 40: 60: 400: 3, pulping, then carrying out spray granulation, drying and roasting at 500 ℃ to obtain the final catalytic cracking catalyst, wherein the final catalyst comprises the following components in percentage by mass: ZSM-5 molecular sieve: kaolin: SBA-15 molecular sieve: alumina =20:8.24:11.76: 60. Catalyst name D-1.
Table 1 nitrogen adsorption-desorption data
Figure DEST_PATH_IMAGE002
TABLE 2 catalytic cracking reaction Performance test
Figure DEST_PATH_IMAGE004
Note: reaction temperature 500 ℃, and catalyst-oil ratio 4: 1. conversion = (raw material amount-slurry amount)/raw material amount
The quantity and the pore structure of the microporous molecular sieve are two important parameters influencing the connectivity of the composite molecular sieve, and the proper content and the better assembly position of the microporous molecular sieve are favorable for reducing the mass transfer resistance of the composite molecular sieve. The C-3 sample prepared in example 3 showed the highest catalytic cracking conversion. The method mainly benefits from the fact that the content of the microporous molecular sieve is high, and the microporous molecular sieve can be better assembled with the structure of mesoporous molecular sieve/kaolin under the condition of ball milling. And the catalytic cracking conversion rate of D-1 is lower compared with that of other samples, which shows that the ball milling crystallization method is more beneficial to the preparation of the catalyst with the micropore-mesopore-macropore channel structure compared with hydrothermal crystallization.
The catalyst prepared by the method has lower dry gas yield and liquefied gas yield, and the final light oil yield and conversion rate are obviously increased due to the fact that the catalyst has a better micropore-mesopore-macropore pore structure.
The above description is only a preferred embodiment of the present invention, and all the equivalent changes and modifications made according to the claims of the present invention should be covered by the present invention.

Claims (8)

1. A preparation method of a catalytic cracking catalyst containing a micropore-mesopore-macropore structure is characterized by comprising the following steps:
(1) preparation of macroporous kaolin solid: roasting kaolin at the temperature of 650-900 ℃, then heating a hydrochloric acid solution with the concentration of 1-6 mol/L to 50-90 ℃, adding a certain amount of kaolin into the acid solution according to the mass ratio of the acid solution to the kaolin of 3-10:1, stirring for 1-8 h, and finally filtering, washing and drying to obtain acidic macroporous kaolin solid;
(2) preparation of mesoporous molecular sieve slurry: mixing a silicon source, an aluminum source, a template agent and deionized water, adjusting the pH value to 10-13, pre-crystallizing at the temperature of 70-150 ℃ for 3-9 h, crystallizing at the temperature of 160-220 ℃ for 4-20 h, and cooling to obtain mesoporous molecular sieve slurry; wherein the mesoporous molecular sieve is an SBA-15, SBA-16, MCM-41 or MCM-22 molecular sieve;
(3) adding the macroporous kaolin solid into the mesoporous molecular sieve slurry, adjusting the pH, completing the crystallization process under the condition of ball milling crystallization, and filtering to obtain a mesoporous-macroporous composite acidic material;
(4) synthesizing the precursor slurry of the microporous molecular sieve nanocrystal: fully mixing a silicon source, an aluminum source, a template agent and deionized water or the silicon source, the aluminum source, a phosphorus source and the deionized water under the stirring condition, adjusting the pH value to 10-13, adding the mixture into a crystallization kettle, then pre-crystallizing the mixture for 4-8 hours at the temperature of 80-100 ℃, crystallizing the mixture for 4-12 hours at the temperature of 160-180 ℃, and cooling the mixture to obtain microporous molecular sieve nanocrystal precursor slurry, wherein the microporous molecular sieve comprises one or more of ZSM-5, Beta, SAPO-11, SAPO-34, Y and mordenite;
(5) adding the mesoporous-macroporous composite acidic material in the step (3) into the step (4), adjusting the pH, completing the rest crystallization process under the condition of ball milling, and filtering, washing, exchanging and drying to obtain an acidic material with a microporous-mesoporous-macroporous structure;
(6) pulping pseudo-boehmite, hydrochloric acid, water and an acidic material with a micropore-mesopore-macropore structure, and performing spray granulation, drying and roasting to obtain a catalytic cracking catalyst;
the speed of ball milling is 200 and 1000 r/min.
2. The method of claim 1, wherein the microporous molecular sieve is ZSM-5 molecular sieve with SiO in the molecular sieve 2 :Al 2 O 3 In the molecular ratio of 25-300: 1 range, SiO in Beta molecular sieve 2 :Al 2 O 3 In the molecular ratio of 25-100: 1 range, Y type molecular sieve SiO 2 :Al 2 O 3 In the molecular ratio of 5.0-7.3: mordenite molecular sieve SiO within 1 range 2 :Al 2 O 3 In the molecular ratio of 5-20: 1, the phosphorus-aluminum ratio of the SAPO-11 molecular sieve is between 0.6 and 1.0: 1, in the range of.
3. The method of claim 1, wherein the mesoporous molecular sieve is pure silicon or aluminum-containing, SiO 2 :Al 2 O 3 In the range of 5 to 500.
4. The method of claim 1, wherein the silicon source used in the mesoporous molecular sieve is one or more of water glass, tetraethoxysilane or silica gel powder, and the aluminum source is sodium metaaluminate, aluminum sulfate or aluminum nitrate.
5. The method of claim 1, wherein in the step (3), the pH value is 10-12.5, the crystallization temperature is 160-180 ℃, the crystallization time is 10-80 h, and the crystallization conditions of the mesoporous molecular sieve are shown.
6. The method of claim 1, wherein in the step (5), the pH value is 10-12.5, the crystallization temperature is 160 ℃ -180 ℃, the crystallization time is 10 h-120 h, and the crystallization condition of the microporous molecular sieve is shown.
7. The method according to claim 1, wherein in the step (6), the mass ratio of the acidic material with the micropore-mesopore-macropore structure, the pseudo-boehmite, the water and the hydrochloric acid is 30-40: 50-60: 400-450: 3-5.
8. The catalytic cracking catalyst containing the micropore-mesopore-macropore structure prepared by the preparation method according to any one of the claims 1 to 7, wherein the components of the catalyst comprise: the composite material comprises a microporous molecular sieve, a mesoporous molecular sieve, macroporous kaolin and alumina, wherein the content of the microporous molecular sieve is 5-35 wt% calculated by the weight of the microporous molecular sieve, the content of the mesoporous molecular sieve is 5-35 wt% calculated by the weight of the mesoporous molecular sieve, the content of the macroporous kaolin is 5-40 wt% calculated by the weight of the macroporous kaolin, the content of the alumina is 30-60 wt% calculated by the weight of the alumina, and the sum of the mass percentages of the components is 100%.
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