CN113546672B

CN113546672B - Catalytic cracking catalyst, preparation method and application thereof, and catalytic cracking method

Info

Publication number: CN113546672B
Application number: CN202110342883.4A
Authority: CN
Inventors: 张杰潇; 于善青; 凤孟龙; 李家兴; 杨民; 田辉平
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2020-04-24
Filing date: 2021-03-30
Publication date: 2023-09-05
Anticipated expiration: 2041-03-30
Also published as: CN113546672A

Abstract

The invention relates to the field of hydrocarbon oil catalytic cracking, and discloses a catalytic cracking catalyst, which comprises the following components: modified ZSM-5 molecular sieve and binder and optionally clay; the content of the modified ZSM-5 molecular sieve based on the dry basis is 20-60 wt%, the content of the clay based on the dry basis is 0-50 wt%, and the content of the binder based on the oxide is 10-40 wt% based on the dry basis of the catalyst; the modified ZSM-5 molecular sieve comprises a ZSM-5 molecular sieve and alkaline earth metal elements; the content of the alkaline earth metal element is 10-30% by weight based on the dry weight of the modified ZSM-5 molecular sieve and calculated by oxide; siO of the modified ZSM-5 molecular sieve ₂ /Al ₂ O ₃ The molar ratio is 15-50. The catalyst has stronger cracking capability when being applied to cracking reaction, and has higher yield of low-carbon olefin and higher propylene selectivity.

Description

Catalytic cracking catalyst, preparation method and application thereof, and catalytic cracking method

Technical Field

The invention relates to the field of catalytic cracking of hydrocarbon oil, in particular to a catalytic cracking catalyst, a preparation method and application thereof and a catalytic cracking method.

Background

In recent years, the propylene productivity of China is rapidly increased, crude oil of China is heavy, light hydrocarbon and naphtha resources are poor, and therefore, the catalytic cracking technology for developing the high-yield propylene is suitable for the requirements of the national conditions of China.

Some research units in China pay great attention to the research on the low-carbon olefin production technology. At the end of the 80 s of the 20 th century, the institute of petrochemical science (abbreviated as "Dan Keyuan") developed a catalytic cracking technology (DCC) for producing low-carbon olefins from heavy oil, which employs a modified five-membered ring medium pore zeolite catalyst, and increased propylene yield under more severe conditions than catalytic cracking by using a riser plus a fluidized bed or riser reactor; when paraffin base is used as raw material, the propylene yield can reach 23%, and the propylene yield of intermediate base raw material is about 17%; the technology is successfully applied to 10 sets of devices at home and abroad. In the 90 th century, a catalytic Cracking (CPP) process technology for directly preparing ethylene and propylene from heavy oil is developed, and the process uses heavy oil or wax oil as raw material, adopts specially developed acid zeolite catalyst with double functions of positive carbon ion reaction and free radical reaction, and is operated at reaction temperature of 580-640 deg.C, large catalyst-oil ratio and high water injection steam quantity, and uses Daqing atmospheric residuum as an example, the ethylene yield can be up to 10% -14%, and the propylene yield can be up to 19% -21%. After 21 st century, dan Keyuan developed a new technology for producing propylene, namely an enhanced catalytic cracking technology (DCC-plus) and a heavy oil selective cracking (MCP) technology, based on DCC technology, and achieved the goal of increasing propylene yield and reducing dry gas and coke yield through zonal control. The research of the propylene-rich catalytic material is also focused on by the petrochemical science institute, and new ZRP series and ZSP series propylene-rich silicon-aluminum materials are developed successively, which plays an important role in the development of the propylene catalyst and the auxiliary agent for catalytic cracking yield increase in China, but the performance of the developed silicon-aluminum materials still needs to be further improved so as to meet the requirement of heavy and poor quality of crude oil.

In order to solve the limitations of the traditional ZSM-5 zeolite in the macromolecular catalytic reaction, researchers have explored different methods.

CN101380591a discloses a preparation method of a toluene disproportionation catalyst of alkali-treated modified ZSM-5 zeolite, which comprises the steps of adding a binder into zeolite raw powder with an active component of ZSM-5 for molding, treating with 0.01-0.4mol/L alkali solution at 25-75 ℃, exchanging into hydrogen zeolite, washing with organic acid, drying the catalyst, carrying out chemical liquid phase deposition modification with cyclohexane solution of tetraethoxysilane, drying, and roasting to obtain the catalyst. The catalyst is especially suitable for toluene shape-selective disproportionation to prepare benzene and paraxylene.

CN102464336a discloses a method for modifying ZSM-5 zeolite, which comprises treating ZSM-5 zeolite with an alkaline solution in a closed system containing a low molecular weight organic solvent; then the ZSM-5 zeolite is treated by acid solution, and finally the modified ZSM-5 zeolite is obtained through separation, washing and drying. The organic solvent added in the method during alkali treatment can promote the generation of a mesoporous structure, so that the microporous structure is more efficiently converted into mesopores, and meanwhile, the microporous structure is stably protected; the subsequent acid treatment process can elute amorphous aluminum in zeolite crystal, thereby achieving the purposes of dredging pore canal and increasing total specific surface area.

CN102910644a relates to a multistage hole ZSM-5 molecular sieve and a preparation method thereof, wherein the method is to prepare the multistage hole ZSM-5 molecular sieve from the ZSM-12 molecular sieve through crystal transformation. The preparation method of the molecular sieve comprises the following steps: and adding ZSM-12 molecular sieve powder into a solution containing sodium hydroxide and tetrapropylammonium bromide at room temperature, uniformly stirring, slowly adding an external silicon source, uniformly stirring to obtain a reaction mixture gel system, and loading the reaction mixture gel into a stainless steel reaction kettle. Crystallizing the reaction mixture under a certain condition under a closed condition to obtain the hierarchical pore ZSM-5 molecular sieve. The molecular sieve provided by the method has micropores and a concentrated mesoporous structure, and can be used for various catalytic processes.

CN103011193a discloses a preparation method of high catalytic activity iron-containing mesoporous ZSM-5, which relates to a preparation method of mesoporous ZSM-5. The method aims to solve the technical problem that mesoporous ZSM-5 prepared by the existing method has low catalytic performance in the catalytic Friedel-crafts alkylation reaction, and is applied to the field of preparation of iron-containing mesoporous ZSM-5.

CN104324746a discloses a metal modified ZSM-5 molecular sieve catalyst and application thereof, and the metal modified ZSM-5 molecular sieve catalyst can be used in the preparation of acrylic acid by lactic acid dehydration.

CN104492476A discloses a modified ZSM-5 molecular sieve and a preparation method thereof, wherein the modified ZSM-5 molecular sieve is prepared by loading metal oxide on a desilicated ZSM-5 molecular sieve, and the metal oxide is MgO, coO, la ₂ O ₃ NiO or CeO ₂ The metal oxide loading is calculated according to the mass ratio of any two or more mixtures of the following materials: desilication ZSM-5 molecular sieve is 0.04-0.05:1. the preparation method comprises the steps of sequentially carrying out desilication treatment on the ZSM-5 zeolite molecular sieve by alkali to obtain a desilication ZSM-5 zeolite molecular sieve, then carrying out treatment on the desilication ZSM-5 zeolite molecular sieve by an ammonium salt solution to obtain a hydrogenated ZSM-5 molecular sieve, and then carrying out metal oxide loading to obtain the modified ZSM-5 molecular sieve. When the catalyst is used for catalyzing alkylation of benzene and methanol to prepare paraxylene, the catalyst shows higher benzene conversion rate, excellent paraxylene selectivity and better activity stability.

CN106140258A provides a catalyst using modified ZSM-5 molecular sieve as carrier, its preparation method and its application in preparing isobutene. The preparation method of the catalyst comprises the following steps: (1) Soaking hydrogen-type ZSM-5 molecular sieve carrier with alkali solution, acid solution and magnesium salt solution of NaOH, KOH or Na ₂ CO ₃ One or more of the aqueous solutions, wherein the concentration of the alkali solution is 0.1mol/L-2mol/L; the acid solution is one or more of hydrochloric acid, nitric acid or sulfuric acid solution, and the concentration of the acid solution is 0.1mol/L-5mol/L; obtaining the product In the obtained modified ZSM-5 molecular sieve carrier, the weight content of magnesium in the carrier is 0.5% -10% in terms of elements; (2) Zinc oxide is introduced into a hydrogen type ZSM-5 molecular sieve carrier after treatment; (3) The hydrogen ZSM-5 molecular sieve carrier after zinc oxide is introduced is subjected to bromination until the weight content of zinc oxide in the catalyst is 0.5% -20%, preferably 1% -15%, further preferably 1% -9%, and the weight content of zinc bromide is 10% -50%, preferably 15% -45%, further preferably 18% -39%. The catalyst prepared by the method can improve the selectivity of isobutene.

In summary, the existing ZSM-5 molecular sieve modification technology carries out acid-base or metal modification to different degrees, however, the pore structure and acidity of the obtained modified ZSM-5 molecular sieve need to be further improved, and the cracking performance is required to be improved when the modified ZSM-5 molecular sieve is applied to the heavy inferior oil catalytic cracking reaction, and the effect of improving the low-carbon olefin yield is not obvious.

Disclosure of Invention

The invention aims to solve the problems of insufficient cracking capacity of heavy inferior crude oil and low yield of low-carbon olefin in the prior art, and provides a catalytic cracking catalyst, a preparation method and application thereof, and a catalytic cracking method.

In order to achieve the above object, a first aspect of the present invention provides a catalytic cracking catalyst comprising: modified ZSM-5 molecular sieve and binder and optionally clay; the content of the modified ZSM-5 molecular sieve based on the dry basis is 20-60 wt%, the content of the clay based on the dry basis is 0-50 wt%, and the content of the binder based on the oxide is 10-40 wt% based on the dry basis of the catalyst;

the modified ZSM-5 molecular sieve comprises a ZSM-5 molecular sieve and alkaline earth metal elements; the content of the alkaline earth metal element is 10-30% by weight based on the dry weight of the modified ZSM-5 molecular sieve and calculated by oxide;

SiO of the modified ZSM-5 molecular sieve ₂ /Al ₂ O ₃ The molar ratio is 15-50;

the mesoporous volume of the modified ZSM-5 molecular sieve accounts for 25-60% of the total pore volume of the modified ZSM-5 molecular sieve;

the ratio of the amount of B acid to the amount of L acid of the modified ZSM-5 molecular sieve is 8-45.

Preferably, in the modified ZSM-5 molecular sieve, the mesoporous volume with the pore diameter of 5nm to 20nm accounts for more than 85% of the total mesoporous volume, more preferably more than 90%, for example, 90-96%.

Preferably, the mesoporous volume of the modified ZSM-5 molecular sieve accounts for 30-50% of the total pore volume of the modified ZSM-5 molecular sieve.

Preferably, the modified ZSM-5 molecular sieve is SiO ₂ /Al ₂ O ₃ The molar ratio is 20-40.

Preferably, the content of the alkaline earth metal element is 12 to 20% by weight, more preferably 14 to 20% by weight, in terms of oxide.

The proportion of the strong acid amount of the modified ZSM-5 molecular sieve to the total acid amount is 35-55%, preferably 40-50%.

Preferably, the modified ZSM-5 molecular sieve has a ratio of B acid to L acid of from 8 to 30, preferably from 10 to 28.

Preferably, the modified ZSM-5 molecular sieve also contains an auxiliary element, and the content of the auxiliary element is 1-15 wt%, preferably 6-12 wt%, and more preferably 7-10 wt% based on the dry weight of the modified ZSM-5 molecular sieve; the auxiliary elements comprise a first auxiliary element and/or a second auxiliary element.

Preferably, the content of the first auxiliary element is 1 to 10 wt%, preferably 5 to 10 wt%, further preferably 5 to 9 wt%, based on the dry weight of the modified ZSM-5 molecular sieve, calculated as oxide; the content of the second auxiliary element is 0.1 to 10, preferably 0.1 to 5, more preferably 1 to 3 wt%.

In a second aspect, the present invention provides a method for preparing a catalytic cracking catalyst, the method comprising:

(1) In the presence of a first solvent, contacting a ZSM-5 molecular sieve with alkali and alkaline earth metal compounds, and then sequentially filtering and drying to obtain a solid product;

(2) Acid solution is adopted to carry out acid treatment on the solid product obtained in the step (1);

(3) Roasting the product after acid treatment to obtain a modified ZSM-5 molecular sieve;

(4) Pulping a modified ZSM-5 molecular sieve, a binder and optionally clay to obtain a slurry, spray drying the slurry and optionally roasting the slurry;

the modified ZSM-5 molecular sieve, the binder and the optional clay are used in an amount such that the content of the modified ZSM-5 molecular sieve in a dry basis is 20-60 wt% based on the dry basis of the catalyst, the content of the clay in a dry basis is 0-50 wt% and the content of the binder in an oxide is 10-40 wt% in the prepared catalyst;

the ZSM-5 molecular sieve and alkaline earth metal compound are used in an amount such that the content of alkaline earth metal element in the prepared modified ZSM-5 molecular sieve is 10-30% by weight based on the dry basis weight of the modified ZSM-5 molecular sieve and calculated as oxide;

SiO of the ZSM-5 molecular sieve ₂ /Al ₂ O ₃ The molar ratio is 15-50.

Preferably, the method further comprises, after step (2), prior to step (3), modifying the product resulting from the acid treatment of step (2), said modifying comprising: and (3) carrying out modification reaction on the product obtained by acid treatment in the step (2) and soluble compounds of the auxiliary agent in the presence of a second solvent.

Preferably, the soluble compounds of the promoter are used in amounts such that the modified ZSM-5 molecular sieve is produced having a content of the promoter element of from 1 to 15% by weight, preferably from 6 to 12% by weight, more preferably from 7 to 10% by weight, on an oxide basis, based on the dry weight of the modified ZSM-5 molecular sieve. The auxiliary elements comprise a first auxiliary element and/or a second auxiliary element.

Preferably, step (4) comprises beating the filtrate obtained by filtering in step (1), the modified ZSM-5 molecular sieve, the binder and optionally the clay.

In a third aspect the present invention provides a catalyst prepared by the above process. The catalyst has the characteristic of strong cracking capacity, and can improve the yield of the low-carbon olefin while keeping the high yield of the liquefied gas in the catalytic cracking reaction.

Accordingly, a fourth aspect of the present invention provides the use of the above catalyst in catalytic cracking.

In a fifth aspect, the present invention provides a method of catalytic cracking, the method comprising: under the condition of catalytic cracking, the hydrocarbon oil is contacted and reacted with a catalyst; the catalyst is the catalyst.

Through the technical scheme, the ZSM-5 molecular sieve is modified by alkaline earth metal, part of silicon in the ZSM-5 molecular sieve is removed, and a framework and surface vacancies are formed, so that the mesoporous structure of the ZSM-5 molecular sieve is enriched, wherein the alkaline site of the alkaline earth metal can reduce the strong acidity of the ZSM-5 molecular sieve, thereby inhibiting the generated olefin from generating hydrogen transfer reaction and stabilizing the generated low-carbon olefin. The modification is carried out by acid, so that part of amorphous aluminum and impurities are removed, the pore structure of the ZSM-5 molecular sieve is improved, and the stability is improved.

According to the embodiment of the invention, when the catalyst prepared by the modified ZSM-5 molecular sieve is used for catalytic cracking, the cracking capacity of the catalyst is stronger, the liquefied gas yield, the ethylene yield and the propylene yield are higher, and the propylene selectivity is higher. Under the preferable condition, the invention adopts the auxiliary agent element to modify the product obtained by the acid treatment in the step (2), so as to improve the cracking performance of the catalyst and further improve the yield of the low-carbon olefin; under the preferred condition, the invention adopts the filtrate generated in the preparation process of the modified ZSM-5 molecular sieve to prepare the catalyst, improves the utilization rate of raw materials, avoids environmental pollution, reduces the preparation cost of the catalyst, and simultaneously improves the problem of higher coke selectivity of the cracking catalyst.

Detailed Description

The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.

In the present invention, the pore diameter refers to a diameter unless specifically stated.

In the invention, the dry weight refers to the weight after firing for 1 hour at 800 ℃.

In a first aspect the present invention provides a catalytic cracking catalyst comprising: modified ZSM-5 molecular sieve and binder and optionally clay; the content of the modified ZSM-5 molecular sieve based on the dry basis is 20-60 wt%, the content of the clay based on the dry basis is 0-50 wt%, and the content of the binder based on the oxide is 10-40 wt% based on the dry basis of the catalyst;

In the invention, the mesoporous volume and the total pore volume are measured by using AS-3 and AS-6 static nitrogen adsorbers manufactured by Quantachrome instruments.

According to the present invention, it is preferable that the content of the modified ZSM-5 molecular sieve in terms of dry basis is 25 to 50% by weight, the content of the clay in terms of dry basis is 12 to 45% by weight, and the content of the binder in terms of oxide is 12 to 38% by weight, based on the dry basis of the weight of the catalyst.

It is further preferred that the modified ZSM-5 molecular sieve is present in an amount of from 25 to 40% by weight on a dry basis, the clay is present in an amount of from 25 to 40% by weight on a dry basis, and the binder is present in an amount of from 20 to 35% by weight on an oxide basis, based on the weight of the catalyst on a dry basis.

In one embodiment, the sum of the modified ZSM-5 molecular sieve content on a dry basis, the clay content on a dry basis, and the binder content on an oxide basis is 100% based on the weight of the catalyst on a dry basis.

In the present invention, the optional clay means that the catalyst may or may not contain clay, and preferably contains clay. The clay of the present invention may be selected from a wide range of materials known to those skilled in the art. Preferably, the clay is at least one selected from the group consisting of kaolin, halloysite, montmorillonite, diatomaceous earth, halloysite, quasi halloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite, and further preferably is kaolin and/or halloysite.

The binder is not particularly limited in terms of its choice, and may be a material known to those skilled in the art. Preferably, the binder is a refractory inorganic oxide, preferably one or more of alumina, silica, titania, magnesia, zirconia, thoria and beryllium oxide, and/or a refractory inorganic oxide precursor, preferably at least one of acidified pseudo-boehmite, alumina sol, silica sol, phosphoalumina gel, silica alumina sol, magnesia alumina sol, zirconia sol and titania sol, preferably acidified pseudo-boehmite and alumina sol.

According to a preferred embodiment of the present invention, the modified ZSM-5 molecular sieve has a mesopore volume with a pore diameter of 5nm to 20nm accounting for 85% or more, more preferably 90% or more, for example, 90 to 96% of the total mesopore volume. In this preferred case, the pore structure of the modified ZSM-5 molecular sieve is advantageous for improving the catalytic performance of the modified ZSM-5 molecular sieve in the catalytic cracking reaction.

According to the present invention, preferably, the mesoporous volume of the modified ZSM-5 molecular sieve accounts for 30-50% of the total pore volume of the modified ZSM-5 molecular sieve. In this preferred case, the formation and diffusion of isomerization and aromatization reaction intermediates and products is favored, thereby avoiding coking deactivation of the modified ZSM-5 molecular sieve.

According to a preferred embodiment of the present invention, the modified ZSM-5 molecular sieve is SiO ₂ /Al ₂ O ₃ The molar ratio is 20-40. In this preferred embodiment, it is more advantageous to improve the cracking performance of the catalyst prepared.

According to a preferred embodiment of the present invention, the alkaline earth metal element is contained in an amount of 12 to 20% by weight, more preferably 14 to 20% by weight, in terms of oxide. The inventors of the present invention found that in this preferred case, it is more advantageous to reduce the strong acidity of the ZSM-5 molecular sieve, thereby suppressing the hydrogen transfer reaction of the produced olefin, and further to improve the yield of the low-carbon olefin.

According to a preferred embodiment of the present invention, the proportion of the strong acid amount of the modified ZSM-5 molecular sieve to the total acid amount is 35 to 55%, more preferably 40 to 50%. In this preferred mode, the hydrogen transfer reaction of the produced olefin is advantageously suppressed, and the yield of the light olefin is advantageously increased.

In the invention, the proportion of the strong acid amount to the total acid amount adopts NH ₃ -TPD method assay.

In the present invention, the strong acid means that the acid center is NH without specific description ₃ The desorption temperature is higher than 300 ℃ corresponding to the acid center.

According to a preferred embodiment of the present invention, the modified ZSM-5 molecular sieve has a ratio of the amount of B acid to the amount of L acid of from 8 to 30, preferably from 10 to 28. In such a preferred embodiment, it is advantageous to suppress hydrogen transfer reaction of the produced olefin, thereby advantageously improving the yield of the low-carbon olefin.

In the present invention, the ratio of the amount of acid B to the amount of acid L is measured by the pyridine adsorption infrared acidity method.

In a preferred embodiment of the present invention, the modified ZSM-5 molecular sieve further contains an auxiliary element, and the content of the auxiliary element is 1 to 15 wt%, more preferably 6 to 12 wt%, and still more preferably 7 to 10 wt% in terms of oxide based on the dry weight of the modified ZSM-5 molecular sieve. In such preferred embodiments, it is advantageous to increase the cracking performance of the catalyst, thereby increasing the yield of light olefins in the cracked reaction product.

According to the catalytic cracking catalyst provided by the invention, the selection range of the auxiliary elements is wider, and preferably, the auxiliary elements comprise a first auxiliary element and/or a second auxiliary element.

The first auxiliary element is selected from a wide range of metal elements, for example, preferably at least one of group IB, group IIB, group IVB, group VIIB, group VIII and rare earth elements. Further preferably, the first auxiliary element is selected from at least one of Zr, ti, ag, la, ce, fe, cu, zn and Mn element, more preferably at least one of Ti, zr and Ce element. In the preferred case, the catalyst has stronger cracking performance and is beneficial to improving the yield of the low-carbon olefin.

The second auxiliary element is selected from a wider range, such as a nonmetallic element, preferably, the second auxiliary element is at least one of B, P and N element, preferably, the second auxiliary element is B element and/or P element. In the preferred case, the catalyst has stronger cracking performance and is beneficial to improving the yield of the low-carbon olefin.

The content selection range of the first auxiliary element and the second auxiliary element is wider, preferably, the content of the first auxiliary element is 1-10 wt%, preferably 5-10 wt%, further preferably 5-9 wt% in terms of oxide based on the dry weight of the modified ZSM-5 molecular sieve; the content of the second auxiliary element is 0.1 to 10, preferably 0.1 to 5, more preferably 1 to 3 wt%. In the preferred case, the catalyst has stronger cracking performance and is beneficial to improving the yield of the low-carbon olefin.

According to a preferred embodiment of the present invention, the alkaline earth metal element is at least one element selected from Mg, ca, sr and Ba, and more preferably is Mg. In such a preferred embodiment, the yield of the light olefins is advantageously increased.

SiO of the ZSM-5 molecular sieve ₂ /Al ₂ O ₃ The molar ratio is 15-50.

According to a preferred embodiment of the present invention, the method for preparing the catalytic cracking catalyst comprises:

The alkaline earth metal compound is used in an amount of 10 to 35 parts by weight, preferably 12 to 20 parts by weight, more preferably 14 to 20 parts by weight, in terms of oxide, relative to 100 parts by weight of the ZSM-5 molecular sieve;

SiO of the ZSM-5 molecular sieve ₂ /Al ₂ O ₃ The molar ratio is 15-50.

The inventor of the invention discovers that the alkaline earth metal is adopted to modify the ZSM-5 molecular sieve, so that part of silicon in the ZSM-5 molecular sieve can be removed, a framework and surface vacancies are formed, and the mesoporous structure of the ZSM-5 molecular sieve is improved; wherein, the alkaline site of alkaline earth metal is beneficial to reducing the strong acidity of ZSM-5 molecular sieve, thereby inhibiting the generated olefin from generating hydrogen transfer reaction and improving the yield of low-carbon olefin.

In the present invention, the term "soluble" means soluble in a cosolvent.

The first solvent in step (1) is selected in a wide range, so long as the environment in which the ZSM-5 molecular sieve is contacted with alkali and alkaline earth metal elements can be provided. Preferably, the first solvent is water. The water is not particularly limited, and water of various hardness, tap water, distilled water, purified water and deionized water which are commonly used, may be used. In one embodiment of the present invention, the first solvent is neutral water, which is also called distilled water.

The amount of the first solvent used in the present invention may be selected in a wide range, and may be appropriately selected according to the amount of the ZSM-5 molecular sieve and the alkali and alkaline earth metal compound, as long as the environment in which the contact in step (1) is allowed can be provided. Preferably, the first solvent is used in an amount of 100 to 1000 parts by weight with respect to 100 parts by weight of the ZSM-5 molecular sieve.

In the present invention, in the step (1), the order of contacting the ZSM-5 molecular sieve with the alkali and alkaline earth metal compound is not particularly limited, and the ZSM-5 molecular sieve may be contacted with the alkali first, with the alkaline earth metal compound first, or with the alkali and alkaline earth metal compound simultaneously.

In the present invention, the first solvent may be introduced alone or with a compound of an alkali or alkaline earth metal. According to one embodiment of the invention, step (1) comprises: contacting the first solvent, the ZSM-5 molecular sieve and an alkali solution and a compound of alkaline earth metal.

According to the present invention, preferably, the contacting conditions of step (1) include: the temperature is 50-90 ℃ and the time is 1-5h; further preferably, the temperature is 60-80℃for a period of 2-3 hours.

In the present invention, the filtration and drying in the step (1) are operations well known to those skilled in the art, and the present invention is not particularly limited.

According to one embodiment of the invention, the process may further comprise, in step (1), washing the solid product obtained after filtration. The conditions of the washing according to the invention are selected in a wide range, preferably the pH of the filtrate obtained after the washing is between 6.5 and 7.5, preferably such that the pH of the filtrate obtained after the washing is greater than 7.

According to a preferred embodiment of the present invention, the ZSM-5 molecular sieve and the alkaline earth metal compound are used in such an amount that the content of the alkaline earth metal element in the resulting modified ZSM-5 molecular sieve is 12 to 20% by weight, more preferably 14 to 20% by weight, on an oxide basis, based on the dry weight of the modified ZSM-5 molecular sieve. In such a preferred embodiment, it is more advantageous to suppress the hydrogen transfer reaction of the produced olefin and to increase the yield of the low-carbon olefin.

According to the present invention, preferably, the ZSM-5 molecular sieve is SiO ₂ /Al ₂ O ₃ The molar ratio is 20-40.

The ZSM-5 molecular sieve is wide in selection range, preferably, the ZSM-5 molecular sieve is at least one selected from an ammonium type ZSM-5 molecular sieve, a Na type ZSM-5 molecular sieve and a hydrogen type ZSM-5 molecular sieve, and preferably, the Na type ZSM-5 molecular sieve.

In the present invention, the ZSM-5 molecular sieve may be obtained commercially or may be prepared by itself according to any of the methods of the prior art.

According to the present invention, preferably, the base is selected from at least one of sodium hydroxide, potassium carbonate and sodium carbonate. The base is further preferably sodium hydroxide from the viewpoint of cost reduction.

According to the invention, preferably, in step (1), the base is introduced in the form of an alkaline solution. The concentration of the alkali solution to be used in the invention is selected in a wide range, and the molar concentration of the alkali solution is preferably 0.1-2mol/L, and more preferably 0.3-0.9mol/L.

According to the present invention, the alkali solution is preferably used in an amount of 1 to 100 parts by weight, preferably 5 to 20 parts by weight, relative to 100 parts by weight of the ZSM-5 molecular sieve.

In the present invention, the selection range of the alkaline earth metal is as described above, and the present invention is not described herein.

The alkaline earth metal compound of the present invention may be selected in a wide range as long as it is soluble in a solvent or in the solvent under the action of a cosolvent. Preferably, the alkaline earth metal compound is selected from at least one of alkaline earth metal oxides, chlorides, nitrates and sulfates, more preferably at least one of magnesium oxide, magnesium chloride, magnesium sulfate and magnesium nitrate.

The selection range of the acid is wide, and the acid can be various acids conventionally used in the field. Specifically, the acid is an organic acid and/or an inorganic acid. Preferably, the acid in step (2) is selected from at least one of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, oxalic acid, citric acid and acetic acid, preferably sulfuric acid and/or oxalic acid, further preferably sulfuric acid and oxalic acid. Under the preferable condition, part of amorphous aluminum and impurities are removed, and the pore structure of the ZSM-5 molecular sieve is improved, so that the stability is improved, and the catalytic performance of the prepared catalyst is improved.

According to the present invention, preferably, the weight ratio of sulfuric acid to oxalic acid is 1:1-4.

According to the present invention, preferably, the acid treatment is such that a modified ZSM-5 molecular sieve is produced having a sodium content of not more than 0.5% by weight on an oxide basis.

The weight content of the acid solution according to the present invention is selected in a wide range, preferably the weight content of the acid solution is 5 to 98 wt%, and more preferably 10 to 30 wt%.

According to the invention, preferably the weight ratio of the acid to the solid product obtained in step (1) on a dry basis is from 0.1 to 5, more preferably from 0.5 to 2. In this preferred case, it is more advantageous to improve the catalytic performance of the catalyst.

In one specific embodiment, in step (2), the solid product obtained in step (1) is pulped with a solvent (preferably water), and then the solid product is subjected to acid treatment with an acid solution.

The conditions for the acid treatment in the step (2) are not particularly limited in the present invention, and preferably, the reaction conditions for the acid treatment in the step (2) include: the temperature is 50-90 ℃ and the time is 1-5h; preferably, the temperature is 60-80 ℃ and the time is 2-3h.

According to a preferred embodiment of the present invention, the method further comprises, after step (2), modifying the product obtained by the acid treatment of step (2) before step (3), said modifying comprising: and (3) carrying out modification reaction on the product obtained by acid treatment in the step (2) and soluble compounds of the auxiliary agent in the presence of a second solvent. In this preferred embodiment, it is advantageous to improve the cracking performance of the catalyst and to improve the yield of light olefins.

According to one embodiment of the invention, the modification comprises: and (3) contacting the product obtained by the acid treatment in the step (2), the second solvent and a soluble compound of an auxiliary agent for modification reaction. The order of the contacting is not particularly limited in the present invention, and the product obtained by the acid treatment in the step (2) may be contacted with the second solvent first and then with the soluble compound of the auxiliary agent; the product of the acid treatment of step (2) may also be contacted with the second solvent prior to contacting the soluble compound of the adjuvant. In the present invention, the introduction of the second solvent is not particularly limited, and specifically, for example, the second solvent may be introduced alone or may be introduced together with the soluble compound of the auxiliary agent.

In the present invention, the second solvent may be selected in a wide range, so long as the soluble compound of the product obtained by the acid treatment in step (2) and the auxiliary agent can be modified. Preferably, the second solvent is water. The water is not particularly limited, and water of various hardness, tap water, distilled water, purified water and deionized water which are commonly used, may be used. In one embodiment of the present invention, the second solvent is neutral water, which is also called distilled water.

The amount of the second solvent used in the method of the invention has a wide selection range, and can be appropriately selected according to the amount of the soluble compound of the product obtained by the acid treatment in the step (2) and the auxiliary agent, so long as the modification reaction in the step can be smoothly performed. Preferably, the second solvent is used in an amount of 100 to 1000 parts by weight based on 100 parts by weight of the product (dry weight) obtained in step (2).

According to the invention, the auxiliary elements preferably comprise a first auxiliary element and/or a second auxiliary element.

In the present invention, the selection ranges of the first auxiliary element and the second auxiliary element are as described above, and the present invention is not described herein.

According to the present invention, the soluble compound of the auxiliary is preferably used in such an amount that the content of the auxiliary element in the produced modified ZSM-5 molecular sieve is 1 to 15% by weight, more preferably 6 to 12% by weight, still more preferably 7 to 10% by weight, on an oxide basis, based on the dry weight of the modified ZSM-5 molecular sieve. In this preferred case, it is advantageous to improve the cracking performance of the catalyst, thereby improving the yield of the lower olefins.

According to a preferred embodiment of the present invention, the soluble compounds of the promoter are used in such an amount that the content of the first promoter element, calculated as oxide, in the resulting modified ZSM-5 molecular sieve is 1 to 10 wt%, preferably 5 to 10 wt%, further preferably 5 to 9 wt%; the content of the second auxiliary element is 0.1 to 10, preferably 0.1 to 5, more preferably 1 to 3 wt%. In such preferred embodiments, it is advantageous to increase the cracking performance of the catalyst, thereby increasing the yield of lower olefins.

According to the present invention, preferably, the conditions of the modification reaction include: the temperature is 50-90 ℃ and the time is 1-5h; preferably, the temperature is 60-80 ℃ and the time is 2-3h.

According to one embodiment of the present invention, the method may further comprise: after the step (2), the acid-treated product is sequentially filtered, washed and dried to obtain the acid-treated product before the acid-treated product of the step (2) is modified. The filtration, washing and drying are all well known operations to those skilled in the art, and the present invention is not particularly limited.

According to the present invention, it is preferable that, after the modification reaction is performed, the product obtained by the modification reaction is sequentially filtered and dried before being calcined in step (3). The filtration and drying are operations well known to those skilled in the art, and the present invention is not particularly limited.

According to the present invention, preferably, the conditions of the firing in step (3) include: the temperature is 500-800 ℃, preferably 550-650 ℃; the time is 1-10 hours, preferably 2-3 hours.

In the present invention, the optional clay in step (4) means that clay may or may not be introduced when beating is performed.

In the present invention, the optional calcination in step (4) means that the slurry is spray-dried and then calcined or not calcined. Preferably, in step (4), the slurry is spray dried and then calcined.

According to a preferred embodiment of the present invention, step (4) comprises: pulping the modified ZSM-5 molecular sieve, the binder and the clay to obtain slurry, and performing spray drying and roasting on the slurry.

The conditions for firing in the step (4) are not particularly limited and may be selected as usual in the art. Specifically, for example, the conditions of the firing in step (4) include: the temperature is 300-880 ℃, preferably 400-700 ℃; the time is 0.5-10h, preferably 1-6h.

According to the present invention, preferably, the modified ZSM-5 molecular sieve, binder, and optional clay are used in amounts such that the catalyst is prepared having a modified ZSM-5 molecular sieve content of 25 to 50 wt% on a dry basis, a clay content of 12 to 45 wt% on a dry basis, and a binder content of 12 to 38 wt% on an oxide basis.

In the present invention, the selection ranges of the clay and the binder are as described above, and the present invention is not described herein.

According to a preferred embodiment of the present invention, step (4) comprises beating the filtrate obtained by filtering in step (1), the modified ZSM-5 molecular sieve, the binder and optionally the clay. Under the preferred embodiment, the filtrate generated in the preparation process of the modified ZSM-5 molecular sieve is recycled in the preparation process of the catalyst, and the filtrate contains Al, si and Mg elements, so that the raw material utilization rate is improved, the environmental pollution is reduced, the energy consumption for preparing the catalyst is reduced, and the coke selectivity of the cracking reaction is reduced.

According to the invention, the total weight content of aluminium in oxide and silicon in oxide in the filtrate obtained by filtration in step (1) is preferably 1 to 20% by weight, preferably 5 to 10% by weight.

According to the present invention, preferably, the filtrate obtained by the filtration in the step (1) is used in such an amount that Al introduced from the filtrate obtained by the filtration in the step (1) is contained in the catalyst obtained on the basis of the dry weight of the catalyst ₂ O ₃ And SiO ₂ The total content of (2) is 5-10 wt%.

According to the invention, the slurry of step (4) preferably has a solids content of 15 to 45% by weight, more preferably 30 to 40% by weight.

According to one embodiment of the present invention, the binder in the step (4) is pseudo-boehmite or alumina sol, and the beating process in the step (4) includes: mixing aluminum sol and pseudo-boehmite, then adding clay, adding acid for acidification, and finally adding the modified ZSM-5 molecular sieve.

The acidification in step (4) is not particularly limited in the present invention, and may be performed according to conventional technical means in the art. The acid used for the acidification in step (4) is selected in a wide range according to the present invention, and may be, for example, an inorganic acid conventionally used in the art, including but not limited to hydrochloric acid. The weight ratio of the acid to pseudo-boehmite in step (4) is preferably from 0.01 to 1.

The spray drying is the prior art, and the invention has no special requirements and is not repeated here.

In a third aspect the invention provides a catalyst prepared by the method described above. The catalyst has stronger cracking capability when being applied to cracking reaction, and has higher yield of low-carbon olefin and higher propylene selectivity.

In a fifth aspect, the present invention provides a method of catalytic cracking, the method comprising: under the condition of catalytic cracking, hydrocarbon oil is contacted with a catalyst to react; the catalyst is the catalyst.

In the present invention, the hydrocarbon oil may be selected in a wide range, and may be selected conventionally in the art, and the present invention will not be described herein.

The reaction conditions for the catalytic cracking of the present invention may be selected in a wide range, and specifically, for example, the reaction conditions may include: the temperature is 400-650 ℃, preferably 580-640 ℃; the ratio of the agent to the oil (weight) is 3-10, preferably 4-8.

According to the present invention, preferably, the method of catalytic cracking further comprises: the catalyst is subjected to hydrothermal aging before the reaction is carried out. The condition selection range of the hydrothermal aging is wide, and preferably, the hydrothermal aging is carried out by adopting 90-100% of water vapor. Further preferably, the conditions of hydrothermal aging further include: the temperature is 700-900 ℃, preferably 750-850 ℃, and the time is 5-24 hours, preferably 10-16 hours.

The present invention will be described in detail by examples.

In the examples below, room temperature refers to 25 ℃, unless otherwise specified;

the raw material specifications used in the examples are as follows:

kaolin: the solid content was 72% by weight, produced by chinese kaolin limited (su zhou).

Sulfuric acid, oxalic acid: analytically pure;

aluminum sol: al (Al) ₂ O ₃ Content 22 wt%, manufactured by ziluta division, chinese petrochemical catalyst limited;

pseudo-boehmite: the solid content was 72 wt%, manufactured by Shandong aluminum, china;

ZSM-5 molecular sieve: qilu division of China petrochemical catalyst Co., ltd (amine-free synthesis);

CGP catalyst: qilu division of China petrochemical catalyst Co., ltd, re ₂ O ₃ 3.2 wt.% of Al ₂ O ₃ Content of 51.2 wt%, na ₂ The O content was 0.15% by weight.

The composition of the catalyst is calculated and determined according to the feeding amount of each raw material.

In the examples, the following methods were used to evaluate the relevant parameters of the catalysts prepared:

(1) Total pore volume:

the measurement was carried out by the RIPP151-90 method in petrochemical analysis method, RIPP test method (Yang Cui edition, scientific Press, 1990).

(2) Wear index:

the measurement was carried out by the RIPP29-90 method in petrochemical analysis method, RIPP test method (Yang Cui edition, scientific Press, 1990).

(3) Microreaction activity (i.e., heavy oil conversion):

the measurement was performed by ASTM D5154-2010 standard method.

(4) Hydrocarbon composition of the reaction product:

the measurement was carried out by the RIPP85-90 method of petrochemical analysis method, RIPP test method (Yang Cui edition, scientific Press, 1990).

(5) Specific surface area of catalyst:

according to GB/T5816-1995 method using Autosorb-1 nitrogen adsorption/desorption apparatus from America Kang Da company, the sample was degassed at 300℃for 6 hours prior to testing;

in the examples, the following methods were used to evaluate relevant parameters of the prepared modified ZSM-5 molecular sieves:

(1) Crystallinity:

measured using the standard method of ASTM D5758-2001 (2011) e 1.

(2)SiO ₂ /Al ₂ O ₃ Molar ratio:

the content of the silicon oxide and the aluminum oxide is calculated and measured by using a GB/T30905-2014 standard method.

(3) The components are as follows:

the fluorescence spectrum analysis is adopted, and the measurement is carried out by referring to a GB/T30905-2014 standard method.

(4) Total specific surface area (SBET), mesoporous volume, total pore volume, mesoporous volume of 5-20 nm:

measured by AS-3 and AS-6 static nitrogen adsorbers manufactured by Quantachrome corporation of America Kang Da, instrument parameters: placing the sample in a sample processing system, and vacuumizing to 1.33X10 at 300 deg.C ^-2 Pa, preserving heat and pressure for 4h, and purifying a sample. Testing purified sample at different specific pressures P/P at liquid nitrogen temperature-196 DEG C ₀ The adsorption capacity and desorption capacity of nitrogen under the condition to obtain N ₂ Adsorption-desorption isotherms. Then calculating the total specific surface area by using a two-parameter BET formula; taking specific pressure P/P ₀ The adsorption amount of =0.98 or less is the total pore volume of the sample; the pore size distribution of the mesoporous part is calculated by using BJH formula, and the mesoporous volume (5-50 nm) and the mesoporous volume (5-20 nm) are calculated by using an integration method.

(5) B acid amount and L acid amount:

the measurement was performed by using FTS3000 type Fourier infrared spectrometer manufactured by BIO-RAD company in U.S., under the following test conditions: pressing the sample into tablet, sealing in an in-situ cell of an infrared spectrometer, and vacuumizing to 10 at 350deg.C ^-3 Pa, maintaining for 1h, desorbing gas molecules on the surface of the sample, and cooling to room temperature. Pyridine vapor with the pressure of 2.67Pa is introduced into the in-situ tank, after being balanced for 30min, the temperature is increased to 200 ℃, and the vacuum is pumped again to 10 DEG C ^-3 Pa, maintaining for 30min, cooling to room temperature, and cooling to 1400-1700cm ^-1 Scanning in the wave number range, and recording an infrared spectrum chart of 200 ℃ pyridine adsorption. Then the sample in the infrared absorption pool is moved to a heat treatment area, the temperature is raised to 350 ℃, and the vacuum is pumped to 10 ^-3 Pa, holding for 30min, cooling to room temperature, and recording infrared spectrogram of pyridine adsorption at 350 ℃. And (3) automatically integrating by an instrument to obtain the acid quantity of B acid and the acid quantity of L acid.

(6) Total acid amount and strong acid amount:

the measurement is carried out by adopting an Autochem II 2920 temperature programming desorption instrument of America microphone company, and the test conditions are as follows: 0.2g of sample to be measured is weighed and put into a sample tube, the sample tube is placed into a heating furnace of a thermal conductivity cell, he gas is used as carrier gas (50 mL/min), the temperature is raised to 600 ℃ at the speed of 20 ℃/min, and impurities adsorbed on the surface of the catalyst are removed by purging for 60 min. Then cooling to 100deg.C, keeping the temperature for 30min, and switching to NH ₃ He mixture (10.02% NH) ₃ +89.98%He) for 30min, and then purging with He gas for 90min until the baseline is stable, so as to desorb the physically adsorbed ammonia gas. And (3) heating to 600 ℃ at a heating rate of 10 ℃/min for desorption, and keeping for 30min, so that the desorption is finished. Detecting the gas component change by adopting a TCD detector, and automatically integrating by an instrument to obtain the total acid quantity and the acid quantity of strong acid, wherein the acid center of the strong acid is NH ₃ The desorption temperature is higher than 300 ℃ corresponding to the acid center.

Example 1

The preparation method of the catalytic cracking catalyst comprises the following specific steps:

(1) ZSM-5 molecular Sieve (SiO) ₂ /Al ₂ O ₃ The molar ratio is 27) 100g (dry weight), 600g neutral water (also called distilled water in the invention), 20g NaOH solution (molar concentration is 0.833 mol/L) and 20g MgO are added, the temperature is raised to 70 ℃, the reaction is carried out for 2 hours, the reaction is carried out after the contact reaction, the reaction is cooled to room temperature, and then the solid product is obtained by filtering, washing and drying in sequence; the filtrate was obtained for use, and the content of the element in the filtrate was determined by the ICP analysis method, and the total weight content of aluminum in terms of oxide and silicon in terms of oxide in the filtrate was 7% by weight, and the specific components are shown in table 1.

(2) Taking 80g (dry basis weight) of the solid product obtained in the step (1), pulping with 640g of water, and then adding 40g of H with the weight content of 20 wt% ₂ SO ₄ 60g of oxalic acid, heating to 70 ℃, and carrying out acid treatment for 2 hours, filtering, washing and drying in sequence;

(3) Taking 50g (dry basis weight) of the product obtained in the step (2), adding 200g of neutral water, 5.23g of zirconium oxychloride, 4.33g of cerium chloride and 1.86g of diammonium hydrogen phosphate, heating to 70 ℃, carrying out modification reaction for 2 hours, sequentially filtering and drying, and roasting at 650 ℃ for 2.5 hours to obtain a modified ZSM-5 molecular sieve S1, wherein specific physicochemical property data are shown in Table 4;

(4) Pulping the modified ZSM-5 molecular sieve obtained in the step (3), pseudo-boehmite, alumina sol, kaolin and hydrochloric acid with the weight concentration of 22% to obtain slurry, wherein the solid content of the slurry is 35% by weight; spray drying the slurry to obtain a microsphere catalyst, and roasting the microsphere catalyst at 500 ℃ for 2 hours to obtain a catalytic cracking catalyst C1, wherein the specific physicochemical properties are shown in Table 5;

the amount of hydrochloric acid having a concentration of 22 wt% was 10.28 parts by weight relative to 100 parts by weight of the modified ZSM-5 molecular sieve;

the weight ratio of the pseudo-boehmite to the alumina sol is 2.25:1, a step of; the amounts of modified ZSM-5 molecular sieve, pseudo-boehmite, alumina sol and kaolin used are such that in the catalyst prepared, the content of the modified ZSM-5 molecular sieve on a dry basis is 35% by weight, the content of clay on a dry basis is 39% by weight and the content of the binder on an oxide basis is 26% by weight, based on the dry basis of the catalyst.

Example 1-1

The catalytic cracking catalyst was prepared according to the method of the present invention, and steps (1), (2) and (3) were the same as in example (1), except that step (4) was performed according to the following procedure:

(4) Pulping the filtrate obtained in the step (1), the modified ZSM-5 molecular sieve obtained in the step (3), pseudo-boehmite, alumina sol, kaolin and hydrochloric acid with the weight concentration of 22% to obtain slurry, wherein the solid content of the slurry is 33% by weight; spray drying the slurry to obtain a microsphere catalyst, and roasting the microsphere catalyst at 500 ℃ for 1h to obtain a catalytic cracking catalyst C1-1;

The amount of hydrochloric acid having a concentration of 22 wt% was 10.28 parts by weight relative to 100 parts by weight of the modified ZSM-5 molecular sieve; the filtrate was used in such an amount that, in the catalyst C1-1 thus obtained, al was introduced from the filtrate based on the dry weight of the catalyst ₂ O ₃ And SiO ₂ The total content of (2) is 7% by weight;

the weight ratio of the pseudo-boehmite to the alumina sol is 2.25:1, a step of;

in the preparation process of the catalyst, the weight ratio of the modified ZSM-5 molecular sieve to the total amount of pseudo-boehmite and aluminum sol calculated by alumina to kaolin calculated on a dry basis is 35:26:39.

comparative example 1

A catalytic cracking catalyst was prepared in the same manner as in example 1, except that 20g of MgO was not added in step (1);

steps (2), (3) and (4) were carried out in the same manner as in example 1 to obtain modified ZSM-5 molecular sieve SD1, and specific physicochemical property data are shown in table 4; catalyst D1 was obtained and the specific physicochemical properties are shown in Table 5.

Comparative example 2

Preparation of modified ZSM-5 molecular sieve according to the preparation method of example 1 in CN107973317A, to obtain modified ZSM-5 molecular sieve SD2, the specific physicochemical property data being shown in Table 4;

catalyst D2 was obtained in the same manner as in step (4) of example 1, and the specific physicochemical properties thereof are shown in Table 5.

Example 2

A catalyst for catalytic cracking was prepared in the same manner as in example 1, except that in step (2), H was contained in an amount of 20% by weight ₂ SO ₄ The dosage of (2) is 80g, and the dosage of oxalic acid is 120g;

steps (1), (3) and (4) were carried out in the same manner as in example 1 to obtain a modified ZSM-5 molecular sieve S2, and specific physicochemical property data are shown in table 4; catalyst C2 was obtained and the specific physicochemical properties are shown in Table 5.

Example 3

A catalytic cracking catalyst was prepared in the same manner as in example 1, except that in step (3), 5.23g of zirconium oxychloride, 4.33g of cerium chloride, 1.86g of diammonium hydrogen phosphate were replaced with 13.08g of zirconium oxychloride;

steps (1), (2) and (4) were carried out in the same manner as in example 1 to obtain a modified ZSM-5 molecular sieve S3, and specific physicochemical property data are shown in table 4; catalyst C3 was obtained and the specific physicochemical properties are shown in Table 5.

Example 4

A catalytic cracking catalyst was prepared in the same manner as in example 1, except that in step (3), 5.23g of zirconium oxychloride, 4.33g of cerium chloride, 1.86g of diammonium hydrogen phosphate were replaced with 10.83g of cerium chloride;

steps (1), (2) and (4) were carried out in the same manner as in example 1 to obtain a modified ZSM-5 molecular sieve S4, and specific physicochemical property data are shown in table 4; catalyst C4 was obtained and the specific physicochemical properties are shown in Table 5.

Example 5

A catalytic cracking catalyst was prepared in the same manner as in example 1, except that in step (3), 5.23g of zirconium oxychloride, 4.33g of cerium chloride, 1.86g of hydrogen diamine phosphate were replaced with 9.3g of hydrogen diamine phosphate;

steps (1), (2) and (4) were carried out in the same manner as in example 1 to obtain a modified ZSM-5 molecular sieve S5, and specific physicochemical property data are shown in table 4; catalyst C5 was obtained and the specific physicochemical properties are shown in Table 5.

Example 6

A catalytic cracking catalyst was prepared in the same manner as in example 1, except that in step (3), 5.23g of zirconium oxychloride, 4.33g of cerium chloride, 1.86g of diammonium hydrogen phosphate were replaced with 2.62g of zirconium oxychloride, 2.17g of cerium chloride, 1g of titanium dioxide, 1.40g of diammonium hydrogen phosphate and 1.33g of boric acid;

steps (1), (2) and (4) were carried out in the same manner as in example 1 to obtain a modified ZSM-5 molecular sieve S6, and specific physicochemical property data are shown in table 4; catalyst C6 was obtained and the specific physicochemical properties are shown in Table 5.

Example 7

A catalytic cracking catalyst was prepared in the same manner as in example 1, except that the ZSM-5 molecular sieve in step (1) was different in the molar ratio of silica to alumina, and the SiO of the ZSM-5 molecular sieve was the same as that of ₂ /Al ₂ O ₃ The molar ratio is 45;

steps (1), (2), (3) and (4) were carried out in the same manner as in example 1 to obtain modified ZSM-5 molecular sieve S7, and specific physicochemical property data are shown in table 4; catalyst C7 was obtained and the specific physicochemical properties are shown in Table 5.

Example 8

A catalytic cracking catalyst was prepared in the same manner as in example 1, except that steps (1), (2) and (4) were conducted in the same manner as in example 1, except that in step (3), the modification reaction was not conducted, namely 50g of the product obtained in step (2) was calcined at 650℃for 2 hours to obtain a modified ZSM-5 molecular sieve S8, and specific physicochemical property data are shown in Table 4; catalyst C8 was obtained and the specific physicochemical properties are shown in Table 5.

Example 9

A catalytic cracking catalyst was prepared in the same manner as in example 1, except that MgO was replaced with CaO of the same mass in terms of oxide. The modified ZSM-5 molecular sieve S9 was obtained, and specific physicochemical property data are shown in Table 4; catalyst C9 was obtained and the specific physicochemical properties are shown in Table 5.

Example 10

A catalytic cracking catalyst was prepared in the same manner as in example 1, except that the amount of NaOH solution in step (1) was 5g and the amount of MgO was 12g. The modified ZSM-5 molecular sieve S10 is obtained, and specific physicochemical property data are shown in Table 4; catalyst C10 was obtained and the specific physicochemical properties are shown in Table 5.

Example 11

A catalytic cracking catalyst was prepared in the same manner as in example 1, except that MgO was replaced with MgCl of the same mass in terms of oxide ₂ . The modified ZSM-5 molecular sieve S11 was obtained, and specific physicochemical property data are shown in Table 4; catalyst C11 was obtained and the specific physicochemical properties are shown in Table 5.

TABLE 1

Element(s)	Al	Si	Na	Mg
					content/(g.L) ^-1 )	0.23	3.05	1.12	0.22

Test example 1

This test example was used to evaluate the performance of the catalytic cracking catalyst prepared in the above example.

Wherein the catalyst and CGP catalyst were blended in a weight ratio of 3:1 in the examples.

The catalyst after the blending was subjected to a 100% steam aging deactivation treatment at 800℃for 12 hours using a fixed fluidized bed apparatus. The catalyst loading was 9g, and the reaction materials were wu-mixed three-material oil, the materials of which are shown in table 2. The reaction temperature was 560℃and the catalyst to oil ratio (by weight) was 6, and the measured catalyst performance parameters are shown in Table 5.

Conversion = gasoline yield + liquefied gas yield + dry gas yield + coke yield

Coke selectivity = coke yield/conversion

TABLE 2

Test example 2

The catalyst was subjected to a 100% steam aging deactivation treatment at 800℃for 12 hours using a fixed fluidized bed apparatus. The reaction raw materials are Shanghai hydrogenated tail oil, and the raw materials are shown in table 3. The reaction temperature is 620 ℃, the catalyst-oil ratio (weight) is 10, and the space velocity is 4h ^-1 The water injection rate (measured according to the weight ratio of the reaction raw materials to the water vapor) is 37.5 percent. The measured catalyst performance parameters are listed in table 6.

Conversion = gasoline yield + liquefied gas yield + dry gas yield + coke yield

Propylene selectivity = propylene yield/liquefied gas yield

Ethylene selectivity = ethylene yield/dry gas yield

Coke selectivity = coke yield/conversion

TABLE 3 Table 3

TABLE 4 Table 4

Modified ZSM-5 molecular sieve	S1	SD1	SD2	S2	S3	S4
							Crystallinity/%	75	85	87	58	72	70
SiO ₂ /Al ₂ O ₃ Molar ratio of	25	22	35	24	23	24
							S _BET /(m ² /g)	289	256	420	224	267	255
(V _{Mesoporous pores} /V _{Total hole} )/％	49	32	58	36	40	38
							(V _5nm-20nm /V _{Mesoporous pores} )/％	96	90	90	90	90	91
(Strong acid amount/total acid amount)/(percent)	41	45	60	44	45	45
							Acid amount of B acid/L acid amount	10	36	15	25	25	22
Na ₂ O content/wt%	0.08	0.09	0.13	0.10	0.08	0.09
							MgO content/wt%	18.9	-	-	14.7	17.6	17.2
CaO content/wt.%	-	-	-	-	-	-
							ZrO ₂ Content/wt%	3.56	3.78	-	3.42	9.1	-
CeO ₂ Content/wt%	3.78	3.91	-	3.69	-	8.9
							TiO ₂ Content/wt%	-	-	-	-	-	-
P ₂ O ₅ Content/wt%	1.89	1.92	7.5	1.88	-	-
							B ₂ O ₃ Content/wt%	-	-	-	-	-	-

Continuous table 4

Modified ZSM-5 molecular sieve	S5	S6	S7	S8	S9	S10	S11
								Crystallinity/%	68	65	71	78	70	88	70
SiO ₂ /Al ₂ O ₃ Molar (mol)Ratio of	23	22	39	25	25	27	24
								S _BET /(m ² /g)	252	240	278	312	278	315	277
(V _{Mesoporous pores} /V _{Total hole} )/％	41	44	46	27	42	46	38
								(V _5nm-20nm /V _{Mesoporous pores} )/％	90	91	93	68	89	92	89
(amount of Strong acid/total)Acid amount)/(percent)	48	44	50	55	46	55	46
								Acid amount of B acid/L acid amount	28	26	15	18	17	18	15
Na ₂ O content/wt%	0.09	0.08	0.10	0.14	0.10	0.11	0.09
								MgO content/wt%	17.9	17.1	18.7	19.3	-	10.86	18.32
CaO content/wt.%	-	-	-	-	17.8	-	-
								ZrO ₂ Content/wt%	-	1.89	3.32	-	3.52	3.53	3.59
CeO ₂ Content/wt%	-	1.86	3.45	-	3.68	3.75	3.65
								TiO ₂ Content/wt%	-	1.77	-	-	-	-	-
P ₂ O ₅ Content/wt%	9.6	1.24	1.78	-	1.91	1.85	1.86
								B ₂ O ₃ Content/wt%	-	1.09	-	-	-	-	-

Note that: v (V) _{Mesoporous pores} /V _{Total hole} Representing the proportion of the mesoporous volume to the total pore volume of the modified ZSM-5 molecular sieve;

V _5nm-20nm /V _{mesoporous pores} Representing the ratio of the mesoporous volume with the aperture of 5nm to 20nm to the total mesoporous volume;

the amount of strong acid/total acid represents the proportion of the amount of strong acid to the total acid;

The amount of acid B/amount of acid L represents the ratio of the amount of acid B to the amount of acid L.

TABLE 5

Continuous table 5

TABLE 6

As can be seen from the data in Table 4, the modified ZSM-5 molecular sieve containing alkaline earth metal elements obtained by the method provided by the invention has more abundant mesopores, higher mesoporous content with the pore diameter of 5nm-20nm, lower proportion of the strong acid to the total acid, lower ratio of the acid amount of B to the acid amount of L, and contribution to the generation and diffusion of intermediate and product of isomerization reaction and aromatization reaction under the synergistic effect of alkaline earth metal elements, thereby reducing coking and deactivation, and contribution to inhibiting hydrogen transfer reaction of generated olefin, and further improving the yield of low-carbon olefin.

As can be seen from the data in tables 5 and 6, when the catalyst prepared by using the modified ZSM-5 molecular sieve of the present invention was used for catalytic cracking, the cracking ability of the catalyst was stronger, the liquefied gas yield, ethylene yield, propylene yield were higher, and propylene selectivity was higher.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims

1. A catalytic cracking catalyst, the catalyst comprising: modified ZSM-5 molecular sieve and binder and optionally clay; the content of the modified ZSM-5 molecular sieve based on the dry basis is 20-60 wt%, the content of the clay based on the dry basis is 0-50 wt%, and the content of the binder based on the oxide is 10-40 wt% based on the dry basis of the catalyst;

the modification ZSiO of SM-5 molecular sieve ₂ /Al ₂ O ₃ The molar ratio is 20-40;

in the modified ZSM-5 molecular sieve, the mesoporous volume with the aperture of 5nm to 20nm accounts for more than 85% of the total mesoporous volume;

the proportion of the strong acid amount of the modified ZSM-5 molecular sieve to the total acid amount is 35-55%;

the ratio of the amount of B acid to the amount of L acid of the modified ZSM-5 molecular sieve is 8-30.

2. The catalyst of claim 1, wherein the modified ZSM-5 molecular sieve is present in an amount of 25-50 wt.% on a dry basis, the clay is present in an amount of 12-45 wt.% on a dry basis, and the binder is present in an amount of 12-38 wt.% on an oxide basis based on the weight of the catalyst on a dry basis.

3. The catalyst according to claim 2, wherein,

the content of the modified ZSM-5 molecular sieve based on the dry basis is 25-40 wt%, the content of the clay based on the dry basis is 25-40 wt%, and the content of the binder based on the oxide is 20-35 wt% based on the dry basis of the catalyst.

4. The catalyst according to claim 1, wherein,

the clay is at least one selected from kaolin, halloysite, montmorillonite, diatomite, halloysite, quasi halloysite, soapstone, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite;

the binder is a refractory inorganic oxide and/or a refractory inorganic oxide precursor.

5. The catalyst according to claim 4, wherein,

the clay is kaolin and/or halloysite;

the heat-resistant inorganic oxide is one or more of aluminum oxide, silicon oxide, titanium oxide, magnesium oxide, zirconium oxide, thorium oxide and beryllium oxide, and the heat-resistant inorganic oxide precursor is at least one of acidified pseudo-boehmite, alumina sol, silica sol, phosphoalumina gel, silica alumina sol, magnesia alumina sol, zirconium sol and titanium sol.

6. The catalyst according to claim 5, wherein,

The heat-resistant inorganic oxide precursor is acidified pseudo-boehmite and alumina sol.

7. The catalyst according to any one of claims 1 to 6, wherein,

in the modified ZSM-5 molecular sieve, the mesoporous volume with the aperture of 5nm to 20nm accounts for more than 90% of the total mesoporous volume.

8. The catalyst according to any one of claims 1 to 6, wherein,

the mesoporous volume of the modified ZSM-5 molecular sieve accounts for 30-50% of the total pore volume of the modified ZSM-5 molecular sieve.

9. The catalyst according to any one of claims 1 to 6, wherein,

the content of the alkaline earth metal element is 12-20% by weight in terms of oxide.

10. The catalyst of any one of claims 1-6, wherein the modified ZSM-5 molecular sieve has a proportion of strong acid to total acid of 40-50%.

11. The catalyst according to any one of claims 1 to 6, wherein,

the ratio of the amount of B acid to the amount of L acid of the modified ZSM-5 molecular sieve is 10-28.

12. The catalyst of any one of claims 1-6, wherein the modified ZSM-5 molecular sieve further comprises an auxiliary element, the auxiliary element being present in an amount of 1-15 wt% on an oxide basis based on the dry weight of the modified ZSM-5 molecular sieve;

The auxiliary elements comprise a first auxiliary element and/or a second auxiliary element;

the first auxiliary element is at least one selected from IB group, IIB group, IVB group, VIIB group, VIII group and rare earth element;

the second auxiliary element is selected from at least one of B, P and N elements.

13. The catalyst according to claim 12, wherein,

the first auxiliary element is selected from at least one of Zr, ti, ag, la, ce, fe, cu, zn and Mn elements;

the second auxiliary agent element is B element and/or P element.

14. The catalyst of claim 13, wherein,

the first auxiliary agent element is at least one of Ti, zr and Ce.

15. The catalyst of claim 12, wherein the promoter element is present in an amount of 6 to 12 wt.% on an oxide basis based on the dry weight of the modified ZSM-5 molecular sieve.

16. The catalyst of claim 15, wherein the promoter element is present in an amount of 7 to 10 weight percent on an oxide basis based on the dry weight of the modified ZSM-5 molecular sieve.

17. The catalyst according to claim 12, wherein,

the content of the first auxiliary agent element is 1-10% by weight based on the dry basis weight of the modified ZSM-5 molecular sieve and calculated by oxide; the content of the second auxiliary element is 0.1-10 wt%.

18. The catalyst of claim 17, wherein,

the content of the first auxiliary agent element is 5-10% by weight based on the dry basis weight of the modified ZSM-5 molecular sieve and calculated by oxide; the content of the second auxiliary element is 0.1-5 wt%.

19. The catalyst of claim 18, wherein,

the content of the first auxiliary agent element is 5-9% by weight based on the dry basis weight of the modified ZSM-5 molecular sieve and calculated by oxide; the content of the second auxiliary element is 1-3 wt%.

20. The catalyst according to any one of claims 1 to 6, wherein,

the alkaline earth metal element is at least one selected from the group consisting of Mg, ca, sr and Ba elements.

21. The catalyst of claim 20, wherein,

the alkaline earth metal element is Mg element.

22. A method of preparing a catalytic cracking catalyst, the method comprising:

SiO of the ZSM-5 molecular sieve ₂ /Al ₂ O ₃ The molar ratio is 20-40.

23. The process of claim 22, wherein the ZSM-5 molecular sieve and the compound of an alkaline earth metal are used in amounts such that the content of the alkaline earth metal element in the resulting modified ZSM-5 molecular sieve is 12 to 20 wt.% on an oxide basis based on the dry weight of the modified ZSM-5 molecular sieve.

24. The method of claim 22, wherein,

The ZSM-5 molecular sieve is at least one selected from ammonium type ZSM-5 molecular sieve, na type ZSM-5 molecular sieve and hydrogen type ZSM-5 molecular sieve.

25. The method of claim 24, wherein,

the ZSM-5 molecular sieve is a Na-type ZSM-5 molecular sieve.

26. The method of claim 22, wherein the base is selected from at least one of sodium hydroxide, potassium carbonate, and sodium carbonate;

the alkali is introduced in the form of an alkali solution, and the molar concentration of the alkali solution is 0.1-2mol/L;

the alkali solution is used in an amount of 1 to 100 parts by weight relative to 100 parts by weight of the ZSM-5 molecular sieve.

27. The process according to claim 26, wherein the base is introduced in the form of an alkaline solution having a molar concentration of 0.3-0.9mol/L;

the alkali solution is used in an amount of 5 to 20 parts by weight relative to 100 parts by weight of the ZSM-5 molecular sieve.

28. The method of claim 22, wherein,

the alkaline earth metal is selected from at least one of Mg, ca, sr and Ba;

the alkaline earth metal compound is selected from at least one of alkaline earth metal oxides, chlorides, nitrates and sulfates.

29. The method of claim 28, wherein,

The alkaline earth metal is Mg element;

the alkaline earth metal compound is at least one of magnesium oxide, magnesium chloride, magnesium sulfate and magnesium nitrate.

30. The method of claim 22, wherein,

the first solvent is used in an amount of 100 to 1000 parts by weight with respect to 100 parts by weight of the ZSM-5 molecular sieve.

31. The method of any one of claims 22-30, wherein the contacting conditions of step (1) comprise: the temperature is 50-90 ℃ and the time is 1-5h.

32. The method of claim 31, wherein the contacting conditions of step (1) comprise: the temperature is 60-80 ℃ and the time is 2-3h.

33. The method of any one of claims 22-30, wherein the acid of step (2) is selected from at least one of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, oxalic acid, citric acid, and acetic acid.

34. The method of claim 33, wherein the acid of step (2) is sulfuric acid and/or oxalic acid.

35. The method of claim 34, wherein the acid of step (2) is sulfuric acid and oxalic acid;

the weight ratio of the sulfuric acid to the oxalic acid is 1:1-4.

36. The method according to any one of claims 22-30, wherein,

The weight content of the acid solution is 5-98 wt%.

37. The method of claim 36, wherein,

the weight content of the acid solution is 10-30 wt%.

38. The method according to any one of claims 22-30, wherein,

the weight ratio of the acid to the solid product obtained in step (1) on a dry basis is between 0.5 and 2.

39. The method according to any one of claims 22-30, wherein,

the reaction conditions of the acid treatment of step (2) include: the temperature is 50-90 ℃ and the time is 1-5h.

40. The method of claim 39, wherein,

the reaction conditions of the acid treatment of step (2) include: the temperature is 60-80 ℃ and the time is 2-3h.

41. The method of any one of claims 22-30, further comprising, after step (2), modifying the product of the acid treatment of step (2) prior to step (3), the modifying comprising: in the presence of a second solvent, carrying out modification reaction on the product obtained by acid treatment in the step (2) and a soluble compound of an auxiliary agent;

42. The method of claim 41, wherein,

the second auxiliary agent element is B element and/or P element.

43. The method of claim 42, wherein,

the first auxiliary agent element is at least one of Ti, zr and Ce.

44. The method of claim 41, wherein,

the soluble compound of the auxiliary agent is used in an amount such that the content of the auxiliary agent element in the prepared modified ZSM-5 molecular sieve is 1-15 wt% based on the dry weight of the modified ZSM-5 molecular sieve and calculated as oxide.

45. The method of claim 44, wherein,

the soluble compound of the auxiliary agent is used in an amount such that the content of the auxiliary agent element in the prepared modified ZSM-5 molecular sieve is 6-12 wt% based on the dry weight of the modified ZSM-5 molecular sieve and calculated as oxide.

46. The method of claim 45, wherein,

the soluble compound of the auxiliary agent is used in an amount such that the content of the auxiliary agent element is 7-10 wt% in terms of oxide based on the dry weight of the modified ZSM-5 molecular sieve in the prepared modified ZSM-5 molecular sieve.

47. The method of claim 41, wherein,

the soluble compound of the auxiliary agent is used in an amount such that the content of the first auxiliary agent element in the prepared modified ZSM-5 molecular sieve is 1-10 wt% in terms of oxide; the content of the second auxiliary element is 0.1-10 wt%.

48. The method of claim 47, wherein,

the soluble compound of the auxiliary agent is used in an amount such that the content of the first auxiliary agent element in the prepared modified ZSM-5 molecular sieve is 5-10 wt% in terms of oxide; the content of the second auxiliary element is 0.1-5 wt%.

49. The method of claim 48, wherein,

the soluble compound of the auxiliary agent is used in an amount such that the content of the first auxiliary agent element in the prepared modified ZSM-5 molecular sieve is 5-9 wt% in terms of oxide; the content of the second auxiliary element is 1-3 wt%.

50. The method of claim 41, wherein,

the conditions of the modification reaction include: the temperature is 50-90 ℃ and the time is 1-5h.

51. The method of claim 50, wherein,

the conditions of the modification reaction include: the temperature is 60-80 ℃ and the time is 2-3h.

52. The method of any one of claims 22-30, wherein the firing conditions of step (3) comprise: the temperature is 500-800 ℃; the time is 1-10h.

53. The method of claim 52, wherein the firing conditions of step (3) comprise: the temperature is 550-650 ℃; the time is 2-3h.

54. The process of any one of claims 22-30, wherein the modified ZSM-5 molecular sieve, binder, and optional clay are used in amounts such that the catalyst is produced having a modified ZSM-5 molecular sieve content of 25-50 wt.% on a dry basis, a clay content of 12-45 wt.% on a dry basis, and a binder content of 12-38 wt.% on an oxide basis, based on the weight of the catalyst on a dry basis.

55. The method of claim 54, wherein,

56. The method of any one of claims 22-30, wherein the clay is selected from at least one of kaolin, halloysite, montmorillonite, diatomaceous earth, halloysite, quasi halloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite, and bentonite;

57. The method of claim 56, wherein the clay is kaolin and/or halloysite;

58. The method of claim 57, wherein the refractory inorganic oxide precursor is an acidified pseudo-boehmite and an alumina sol.

59. The process of any one of claims 22-30, wherein step (4) comprises beating the filtrate from the filtering of step (1), the modified ZSM-5 molecular sieve, the binder, and optionally the clay.

60. The method according to any one of claims 22-30, wherein,

the total weight content of aluminum in terms of oxide and silicon in terms of oxide in the filtrate obtained by filtering in the step (1) is 1-20 wt%.

61. The method of claim 60, wherein,

The total weight content of aluminum in terms of oxide and silicon in terms of oxide in the filtrate obtained by filtering in the step (1) is 5-10 wt%.

62. The process of any one of claims 22 to 30, wherein the filtrate from step (1) is used in an amount such that the catalyst is obtained, based on the dry weight of the catalyst, and the filtrate from step (1) is introduced with Al ₂ O ₃ And SiO ₂ The total content of (2) is 5-10 wt%.

63. The method according to any one of claims 22-30, wherein,

the slurry in step (4) has a solids content of 15 to 45% by weight.

64. The method of claim 63, wherein,

the slurry in step (4) has a solids content of 30 to 40% by weight.

65. A catalyst prepared by the method of any one of claims 22-64.

66. Use of the catalyst of any one of claims 1-21 and 65 in catalytic cracking.

67. A method of catalytic cracking, the method comprising: under the condition of catalytic cracking, the hydrocarbon oil is contacted and reacted with a catalyst; the catalyst is the catalyst of any one of claims 1-21 and 65.