CN112473723A

CN112473723A - High-acid-content catalyst, preparation method thereof and method for carbon four-alkylation reaction

Info

Publication number: CN112473723A
Application number: CN201910866448.4A
Authority: CN
Inventors: 周顺利; 张成喜; 李永祥; 罗一斌; 舒兴田
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: 2019-09-12
Filing date: 2019-09-12
Publication date: 2021-03-12

Abstract

The invention relates to a high-acid-content catalyst, a preparation method thereof and a method for a carbon four-alkylation reaction. The catalyst comprises a molecular sieve and an aluminum sol, wherein the weight ratio of the molecular sieve to the aluminum sol is 99:1 to 20:80 on a dry basis; the average particle size of the aluminum sol is less than 20 nm. The acid content of the catalyst disclosed by the invention is greatly improved, the high-acid-content catalyst has the advantages of good reaction activity, high selectivity and long service life, and the preparation process of the catalyst is simple and is suitable for large-scale industrial production.

Description

High-acid-content catalyst, preparation method thereof and method for carbon four-alkylation reaction

Technical Field

The present disclosure relates to a high acid catalyst, a method of making the same, and a method of conducting a carbo-tetra alkylation reaction.

Background

The molecular sieve has a regular three-dimensional pore channel structure, is suitable for acidity and low in price, is beneficial to the diffusion of reactant molecules in the pore channels of the molecular sieve and the reaction of the reactant molecules in an acid center, and is widely applied to the fields of petrochemical industry and the like, particularly the fields of catalytic cracking, hydrogenation, reforming, isobutane-butene alkylation, benzene-olefin alkylation and the like, so that the molecular sieve catalyst has important academic value and wide application prospect. The number and strength of the acid sites of a molecular sieve catalyst are major factors affecting reaction activity and catalyst life. In the catalytic reaction, if the reactant cannot be removed from the active site or diffuse out of the pore channel in time, the reactant continues to react to generate macromolecular olefin to form carbon deposit to cover the active site or block the pore channel, so that the active center is inactivated. At present, molecular sieves are commonly adopted in industry to expand pores in the molecular sieves to form multi-level pores, so that reactants can diffuse into and out of the pore channels quickly.

In industrial applications, molecular sieves are mixed with additives such as binders to form catalysts having certain sizes, shapes and strengths. It is believed that the addition of the binder covers the active sites of the molecular sieve and negatively affects the acid properties of the catalyst. In the traditional technology, silica sol and alumina are used as binders, but the catalytic activity is low due to the fact that the content of the molecular sieve is too low when the usage amount is large.

CN107511164A discloses a technique for realizing the formation of molecular sieve by using a small amount of silica-alumina gel as a binder. The method adopts a small amount of silica-alumina gel as a binder to prepare the catalyst. However, the amount of catalyst acid is somewhat reduced compared to pure molecular sieves.

Disclosure of Invention

The object of the present disclosure is to provide a high acid catalyst having improved acid properties, a method for preparing the same, and a method for conducting a C-tetra alkylation reaction using the same.

In order to achieve the above object, the first aspect of the present invention provides a high acid catalyst comprising a molecular sieve and an aluminum sol, the weight ratio of the molecular sieve to the aluminum sol being 99:1 to 20:80 on a dry basis, the aluminum sol having an average particle diameter of less than 20 nm.

Optionally, the weight ratio of the molecular sieve to the aluminum sol is 95:5 to 25:75, preferably 90:10 to 50:50 on a dry basis.

Optionally, the average particle size of the aluminum sol is less than 15 nm.

Optionally, the pH of the aluminum sol is 1-5, and the concentration is 0.1-50 wt%.

Optionally, the average particle size of the molecular sieve is 0.01-50 μm, and the silica-alumina ratio of the molecular sieve is 1-1000.

Optionally, the molecular sieve is a hydrogen type molecular sieve, and the hydrogen type molecular sieve is one or more of an X type molecular sieve, a Y type molecular sieve, a beta type molecular sieve, a ZSM-5 type molecular sieve, an MCM-22 type molecular sieve, an MCM-41 type molecular sieve and a mordenite type molecular sieve.

Alternatively, NH is used₃-the ratio of the total acid amount of the catalyst to the total acid amount of the molecular sieve as measured by the TPD method is 1.5 or more.

A second aspect of the present disclosure provides a method of preparing a high acid catalyst, the method comprising: mixing a molecular sieve, alumina sol, acid and water to obtain a mixed material, and forming the mixed material to obtain a catalyst precursor; wherein the dosage ratio of the molecular sieve to the aluminum sol is 99:1 to 20:80 based on dry weight, and the average particle size of the aluminum sol is less than 20 nm.

The average grain diameter of the aluminum sol is less than 15 nm; the pH of the aluminum sol is 1-5, and the concentration is 0.1-50 wt%.

Alternatively, the molecular sieve and the aluminium sol are used in a ratio of 95:5 to 25:75, preferably 90:10 to 50:50, on a dry weight basis.

Optionally, the acid is one or more of hydrochloric acid, nitric acid, oxalic acid and citric acid; the acid is added in the form of an acid solution, and the concentration of the acid solution is 1-10 wt%.

Optionally, the method further comprises: drying and/or roasting the catalyst precursor to obtain the high-acid-content catalyst; the drying conditions are such that the dry weight of the catalyst after drying is 60% or more. The roasting conditions comprise: the roasting temperature is 450-650 ℃, and the roasting time is 1-6 h.

Optionally, the method further comprises: adding a lubricant and/or a pore-forming agent into the mixed material, wherein the lubricant is selected from one or more of sesbania powder, methyl cellulose, polyether, polyvinyl alcohol, chitosan and cyclodextrin; the pore-forming agent is selected from one or more of sesbania powder, methyl cellulose, polyether, polyvinyl alcohol, chitosan and cyclodextrin; the lubricant is used in an amount of 0-0.3 parts by weight and the pore-forming agent is used in an amount of 0-0.3 parts by weight based on 1 part by weight of the molecular sieve on a dry basis.

Optionally, the average particle size of the molecular sieve is 0.01-50 μm, and the silicon-aluminum atomic ratio of the molecular sieve is 1-1000.

A third aspect of the present disclosure provides a high acid catalyst prepared by the method of the second aspect of the present disclosure.

A fourth aspect of the present disclosure provides a method of a four-carbon alkylation reaction, the method comprising: contacting the high acid catalyst described in the first and third aspects of the present disclosure with a carbon four feedstock under alkylation reaction conditions.

Optionally, the alkylation reaction conditions include: the reaction temperature is 30-100 ℃, and the reaction pressure is 0.5-6.0 MPa; the carbon four feedstock comprises isobutane and butenes.

Through the technical scheme, the high-acid-content catalyst has the advantages of obviously improved acid property, greatly improved acid content, good reaction activity, high selectivity, long service life and simple preparation process, and is suitable for large-scale industrial production.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

FIG. 1 SEM image of SB powder of comparative example 2 of the present disclosure;

FIG. 2 SEM image of V250 powder of comparative example 3 of the present disclosure;

FIG. 3 SEM image of nano alumina of comparative example 1 of the present disclosure;

fig. 4 SEM image of # 1 aluminum sol of example 1 of the present disclosure.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The invention provides a high-acid-content catalyst, which comprises a molecular sieve and an aluminum sol, wherein the weight ratio of the molecular sieve to the aluminum sol is 99: 1-80: 20 on a dry basis; the average particle diameter of the aluminum sol is less than 20 nm.

The inventors of the present invention have found that the addition of a binder does not only have a negative effect on the acid properties of the catalyst. The present inventors have made extensive experiments to provide a novel molecular sieve catalyst. The catalyst takes alumina sol with the particle size less than 20nm as a binder, and the acid content of the catalyst can be greatly improved by using a small amount of the binder; the high-acid catalyst has the advantages of good reaction activity, high selectivity, long service life and simple preparation process, and is suitable for large-scale industrial production.

In the high acid catalyst according to the present disclosure, the content of the alumina sol binder may vary within a wide range, for example, the weight ratio of the molecular sieve to the alumina sol may be from 99:1 to 20:80 on a dry basis; preferably 95:5 to 25: 75; further preferably 90:10 to 50: 50. Wherein, the molecular sieve dry basis and the alumina sol dry basis are the amounts obtained by roasting at 600 ℃.

In the high acid catalyst according to the present disclosure, the particle size of the aluminum sol may vary within a wide range, for example the average particle size of the aluminum sol may be less than 20nm, such as less than 19nm, preferably less than 15nm, such as 0.01 to 15nm or 0.005 to 19.5nm or 0.002 to 19.8nm, the average particle sizes described in the present disclosure being tested using the Zeta potential method, respectively.

Further, in order to improve the bonding effect of the alumina sol binder and improve the acid property of the catalyst, in one embodiment, the pH of the alumina sol may be 1 to 5; the concentration of the aluminum sol may be 0.1 to 50 wt%.

In the high acid catalyst according to the present disclosure, the grain size of the molecular sieve is not particularly limited and may vary over a wide range, for example, the average particle size of the molecular sieve may be 0.01 to 50 μm; preferably, the average particle size of the molecular sieve is 0.02-25 μm or 0.05-10 μm, more preferably 0.1-3 μm; the silicon-aluminum atomic ratio of the molecular sieve can also be changed in a large range, such as 1-1000; preferably, the molecular sieve has a silicon-aluminum atomic ratio of 1.5 to 100, more preferably 1.5 to 50, and still more preferably 2 to 10.

Further, the molecular sieve is preferably a hydrogen type molecular sieve, the hydrogen type molecular sieve can be one or more of an X type molecular sieve, a Y type molecular sieve, a beta type molecular sieve, a ZSM-5 type molecular sieve, an MCM-22 type molecular sieve, an MCM-41 type molecular sieve and a mordenite type molecular sieve, and is preferably one or more of an X type molecular sieve, a Y type molecular sieve and a beta type molecular sieve.

The catalyst of the present disclosure has superior acid properties, employing NH₃The total acid content of the catalyst, measured by the TPD method, can be significantly increased. A kind ofIn an embodiment, NH is used₃-total acid content of the catalyst measured by the TPD method and using NH₃-the ratio of the total acid content of the molecular sieve as determined by the TPD method is above 1.5; that is, the total acid content of the catalyst comprising the alumina sol of the present application can be increased by more than 50% compared to the corresponding pure molecular sieve in the hydrogen form.

A second aspect of the present disclosure provides a method of preparing a high acid catalyst, the method comprising the steps of: mixing and molding a molecular sieve, alumina sol, acid and optional water to obtain a catalyst precursor; wherein the molecular sieve and the aluminum sol can be used in a ratio of 99:1 to 20:80 on a dry basis; preferably 95:5 to 25: 75; further preferably from 90:10 to 50: 50; the average particle size of the aluminum sol may be less than 20nm, such as less than 19nm, preferably less than 15nm, such as 0.1 to 15nm, or 0.5 to 19.5nm, or 0.2 to 19.8 nm.

The method has simple preparation process and is suitable for large-scale industrial production; the catalyst prepared by the method has the advantages of obviously improved acid content, good reaction activity, high selectivity and long service life.

In the preparation method according to the present disclosure, the manner of mixing the molecular sieve, the alumina sol, the acid and the water is not particularly limited, and for example, the molecular sieve, the alumina sol, the acid and the water may be simultaneously added to the reaction system to be mixed, or two or three of the molecular sieve, the aluminum source, the acid and the water may be mixed and then mixed with the remaining raw materials. In one embodiment of the present disclosure, the acid may be mixed with water to form an acid solution, which is then added to the mixture of the molecular sieve and the aluminum sol.

In the method according to the present disclosure, the addition amount of the acid may be selected according to the sol coefficient of the aluminum source used to obtain a further stable aluminum sol; wherein the sol factor of the alumina sol refers to the amount of acid required by the alumina to form a stable alumina gel having a Zeta potential of 0. For example, in one embodiment, the aluminum sol has a sol factor of 0.05ml/g, (the amount of acid added) of 0.05ml/g (mass of added alumina on a dry basis).

In the method according to the present disclosure, the acid used is also not particularly required, and may be an inorganic acid, preferably at least one of hydrofluoric acid, nitric acid, hydrochloric acid, and sulfuric acid, and/or an organic acid, preferably at least one of formic acid, acetic acid, oxalic acid, and citric acid; further preferably an inorganic acid, more preferably nitric acid and/or hydrochloric acid. In a further embodiment, the acid is added in the form of an acid solution to facilitate the formation of a more stable aluminum sol; the concentration of the acid solution may be 1 to 10 wt%, preferably 3 to 8 wt%.

In the method according to the present disclosure, the aluminum sol may be a commercially available product or obtained by a conventional preparation method, for example, an aluminum source and an acid solution may be contacted under sol-forming conditions to obtain the aluminum sol.

Among them, the kind of the aluminum source may be selected from a wide range, and is preferably one or more of pseudo-boehmite, aluminum hydroxide, aluminum sulfate, aluminum nitrate and aluminum chloride, and more preferably pseudo-boehmite. The acid solution used is also not particularly limited, and may be an aqueous solution of an inorganic acid and/or an organic acid, preferably an aqueous solution of at least one of hydrofluoric acid, nitric acid, hydrochloric acid, sulfuric acid, formic acid, acetic acid, oxalic acid, and citric acid; more preferably an aqueous solution of nitric acid and/or hydrochloric acid.

Wherein, the conditions for forming the sol can be changed in a large range, and preferably, the conditions for forming the sol can comprise: the reaction temperature is 10-80 ℃, preferably 20-50 ℃, and the reaction time is 0.01-48 h, preferably 0.1-24 h; further, the adding amount of the acid can be controlled so that the pH value of the aluminum sol is 1-5.

For example, in one embodiment, an aluminum source such as pseudoboehmite may be mixed with water, and an acid such as nitric acid may be added dropwise to the mixture of pseudoboehmite and water while stirring until the sol is completely peptized to form a stable colloid, i.e., an aluminum sol, without precipitation; the temperature of the mixture in the dropping process can be 25-50 ℃, the pH value can be 1-5, and the stirring reaction time can be 0.01-24 h.

In the method according to the present disclosure, the catalyst precursor may be further dried and calcined to obtain the high acid catalyst; the drying and calcining conditions may be conventional in the art, for example, the drying conditions may be such that the dried catalyst has a dry weight of 60% or more, preferably 80% or more, and more preferably 90 to 100%. The conditions for the firing may include: the roasting temperature is 450-650 ℃, preferably 500-600 ℃, and the roasting time can be 0.5-8 hours, preferably 1-6 hours.

In the method of the present disclosure, in one embodiment, a lubricant and/or a pore-forming agent may be added to the mixed material, and the lubricant and/or the pore-forming agent may be a kind conventional in the art, and preferably, the lubricant is selected from one or more of sesbania powder, methylcellulose, polyether, polyvinyl alcohol, chitosan and cyclodextrin; the pore-forming agent is selected from one or more of sesbania powder, methyl cellulose, polyether, polyvinyl alcohol, chitosan and cyclodextrin; the amount of lubricant and pore former may vary within wide limits, preferably the amount of lubricant may be 0 to 0.3 parts by weight, preferably 0 to 0.1 parts by weight, more preferably 0 to 0.05 parts by weight, based on 1 part by weight of the molecular sieve on a dry basis; for example, 0.001 to 0.3 parts by weight, 0.001 to 0.1 parts by weight, 0.02 to 0.2 parts by weight, or 0.01 to 0.05 parts by weight, and the pore-forming agent may be used in an amount of 0 to 0.3 parts by weight, preferably 0 to 0.2 parts by weight, more preferably 0 to 0.1 parts by weight; for example, 0.001 to 0.3 part by weight, 0.001 to 0.1 part by weight, 0.02 to 0.2 part by weight, or 0.01 to 0.05 part by weight. In a further preferred embodiment, at least one auxiliary agent selected from sesbania powder, methylcellulose and polyether can be added to the mixed material as a lubricant and pore-forming agent, and in this embodiment, the weight ratio of the molecular sieve to the auxiliary agent in terms of silicon oxide can be 1: (0.001 to 0.3), preferably (0.02 to 0.2).

In the high acid catalyst according to the present disclosure, the grain size of the molecular sieve is not particularly limited and may vary over a wide range, for example, the average particle size of the molecular sieve may be 0.01 to 50 μm; preferably 0.05 to 10 μm, more preferably 0.1 to 3 μm; the silicon-aluminum atomic ratio of the molecular sieve can also vary within a wide range, for example, 1 to 1000, preferably, the silicon-aluminum atomic ratio of the molecular sieve is 1.5 to 100, more preferably 2 to 100.

In the process according to the present disclosure, the molecular sieve may be commercially available or synthesized by conventional methods in the art, for example, a molecular sieve synthesized by hydrothermal crystallization well known in the art and optionally subjected to ammonium exchange, calcination and acid treatment.

In the method of the present disclosure, the direct molding of the molecular sieve with the aluminum source and the acid may be performed by an extrusion molding method. The size of the formed catalyst is not particularly required, and can be the conventional size in the field, for example, the catalyst can be a cylinder with the length of 0.3-1.2 cm, the cross section of the cylinder is circular, square, clover, annular or star, and the radial size of the cross section can be 0.05-0.2 cm.

The catalysts of the present disclosure have superior acid properties, specifically in one embodiment, with NH₃The total acid amount of the catalyst measured by the TPD method is that the acid amount of the catalyst can be improved by more than 50% compared with the H-type molecular sieve.

A third aspect of the present disclosure provides a high acid catalyst prepared using the above method. By NH₃The total acid content of the catalyst, measured by the TPD method, is significantly increased. In one embodiment, NH is used₃-total acid content of said molecular sieve determined by the TPD method and using NH₃-the ratio of the total acid amount of the catalyst measured by the TPD method is above 1.5, i.e. the total acid amount of the catalyst comprising an alumina sol prepared by the method of the present disclosure is increased by more than 50% compared to pure molecular sieve.

A fourth aspect of the present disclosure provides a method for conducting a carbo-tetra alkylation reaction using the above catalyst, the method comprising: the high acid catalyst of the present disclosure and the carbon four feedstock are contacted under alkylation reaction conditions.

Wherein, the reaction raw materials and reaction conditions are not particularly limited and may be conventional in the art, for example, the alkylation reaction conditions may include: the reaction temperature is 30-100 ℃, preferably 40-90 ℃, and the reaction pressure can be 0.5-6 MP, preferably 1-5 MP; the carbon four feedstock may comprise isobutane and butene, for example as a mixture of isobutane and butene, wherein the mass ratio of isobutane to butene may be one of 150, 200, 250 or a range of values between any two thereof.

The following examples will further illustrate the present disclosure, but are not intended to limit the same accordingly. In the following examples of the present disclosure, the chemical agents used are all commercially available products unless otherwise specified. Wherein, the Y molecular sieve, the ZSM-5 molecular sieve, the MCM-22 molecular sieve, the beta molecular sieve, the MOR type molecular sieve and the MCM-41 type molecular sieve are all purchased from China petrochemical catalyst company, and a plurality of aluminum sol samples are purchased from China petrochemical catalyst company

The silicon-aluminum ratio of the molecular sieve is determined by a chemical analysis method. The acidic nature of the high acid catalyst described in this invention employs NH₃-TPD fragmentation mode determination. The particle size of the molecular sieve is determined by a laser particle size method, and the particle size of the alumina sol is determined by a Zeta potential method.

Comparative example 1

90gY molecular sieve (Si/Al atomic ratio 15, average particle size of molecular sieve is 2 μm) as active component, 10g nanometer alumina (average particle size 100nm) as binder, the ratio of molecular sieve to binder is 90:10 on dry basis, 80mLH is added₂O、2mL HNO₃And 2g of sesbania powder. Uniformly mixing, and preparing the precursor of the strip molecular sieve catalyst with the butterfly-shaped cross section of the Y molecular sieve by extrusion molding.

And drying the Y molecular sieve catalyst precursor prepared in the last step, and roasting the dried Y molecular sieve catalyst precursor for 4 hours at 600 ℃ in an air atmosphere to obtain the Y molecular sieve catalyst Y1, wherein the dry weight of the dried Y molecular sieve catalyst precursor is 80%.

Example 1

The 90gY molecular sieve (Si/Al atomic ratio 15, average particle size of molecular sieve 2 μm) was used as the active component, 50g of No. 1 alumina sol (sol concentration 20 wt%, average particle size 5nm, pH3.5) was used as the binder, and the ratio of molecular sieve to alumina sol binder was 90:10 on a dry basis.Sieving the above Y-molecular sieve, binder, 80mLH₂O、2mL HNO₃And 2g of sesbania powder are uniformly mixed, and a strip-shaped molecular sieve catalyst precursor with a butterfly-shaped cross section of the Y molecular sieve is prepared by extrusion molding.

And drying the Y molecular sieve catalyst precursor prepared in the last step, and roasting the dried Y molecular sieve catalyst precursor for 4 hours at 600 ℃ in an air atmosphere to obtain the Y molecular sieve catalyst Y2.

Comparative example 2

The method of comparative example 1 was used except that 100g of a # 1 ZSM-5 molecular sieve (Si/Al ratio Si/Al 7, average particle size of molecular sieve 40 μm) was added, the oxide support was SB powder (available from china petrochemical catalyst), the average particle size was 150 μm, and the amount added was 100g, wherein the weight ratio of molecular sieve to binder was 50:50, 20mL of HCl, and 200mL of H was added₂O, 20g of sesbania powder. The ZSM-5 molecular sieve catalyst obtained is marked as ZSM-1.

Example 2

The method of comparative example 2 was used except that the binder was No. 1 alumina sol (sol concentration 50 wt%, average particle diameter 5nm, pH3.5) added in an amount of 500g, and HNO was added₃The amount was 10mL, and 100mL of H was added₂O, 20g of sesbania powder. Obtaining the ZSM-5 molecular sieve catalyst ZSM-2.

Comparative example 3

The method of comparative example 1 was used except that 120g of MCM-22 molecular sieve (Si/Al ratio: 12, average particle size of molecular sieve 0.5 μm) was added and the binder V250 powder (particle size range 5-200 μm, average particle size 100 μm) was added in an amount of 80g, wherein the weight ratio of molecular sieve to binder was 60:40, 10mL of HCl, 150mL of H on a dry basis₂O, 15g of sesbania powder. The MCM-22 molecular sieve catalyst obtained is marked as MCM-1.

Example 3

The method of comparative example 3 was used except that 1600g of 2# aluminum sol (sol concentration 5 wt%, average particle diameter 18nm, pH 5), 3mLHCl, 15g of sesbania powder, 40mLH₂And O. The MCM-22 molecular sieve catalyst obtained is marked as MCM-2.

Comparative example 4

The procedure of comparative example 1 was followed except that the molecular sieve was beta molecular sieve (Si/Al 9, average particle size of molecular sieve 0.2 μm) added in an amount of 80g, and the binder was 100g of # 3 alumina sol (sol concentration 20%, average particle size 500nm, PH 1) added in a weight ratio of molecular sieve to alumina sol binder of 80:20 on a dry basis, and 2mL of HNO was added₃，15mLH₂O, 2g of sesbania powder. To obtain beta molecular sieve catalyst beta-1.

Example 4

The method of comparative example 4 was employed, except that 4000g of # 4 alumina sol (sol concentration 0.5%, average particle diameter 15nm, pH3.4) and 1.5mL of HCl were added as the binder, to obtain beta-molecular sieve catalyst beta-2.

Comparative example 5

The procedure of comparative example 4 was followed except that the molecular sieve added was an MOR type molecular sieve (Si/Al 7.5, average particle size of molecular sieve 1.5 μm), and the resulting catalyst was an MOR-1 catalyst.

Example 5

The procedure of example 4 was followed except that the molecular sieve added was an MOR type molecular sieve to give a catalyst which was MOR-2 catalyst.

Comparative example 6

The process of comparative example 4 was used except that the molecular sieve added was an MCM-41 type molecular sieve (Si/Al ═ 9, average particle size of the molecular sieve particles was 15 μm), and the resulting catalyst was an MCM-3 catalyst.

Example 6

The procedure of example 4 was followed except that the molecular sieve added was an MCM-41 type molecular sieve (Si/Al ═ 9, average particle size of the molecular sieve was 15 μm). Obtaining the catalyst MCM-4 catalyst.

Example 7

The method of example 1 is used with the difference that: the weight ratio of molecular sieve to alumina sol binder was 96:4 on a dry basis. To obtain the Y-3 catalyst.

Comparative example 7

The method of example 1 is used with the difference that: the weight ratio of molecular sieve to alumina sol binder was 15:85 on a dry basis. Obtaining the Y-4 catalyst.

Comparative example 8

The method of example 1 is used with the difference that: the weight ratio to the alumina sol binder was 99.8:0.2 on a dry basis. The Y-5 catalyst is obtained.

Example 8

The method of example 1 was used except that the 1# aluminum sol was replaced with an equivalent amount of 5# aluminum sol (sol concentration 25 wt%, average particle diameter 0.78nm, pH 5). The Y-6 catalyst is obtained.

Example 9

The method of example 1 was used except that sesbania powder was not added. The Y-7 catalyst was obtained.

Example 10

The procedure of example 2 was followed except that the molecular sieve added was a 2# ZSM-5 molecular sieve (silica to alumina ratio Si/Al 7, average particle size of the molecular sieve was 60 μm). Obtaining the ZSM-3 catalyst.

Example 11

The procedure of example 3 was followed except that 400g of # 1 alumina sol (sol concentration 20 wt%, average particle size 5nm, pH3.5) and 2.9mL of HCl were added as the binder, and the MCM-22 molecular sieve catalyst obtained was designated as MCM-5.

Test example 1: scanning Electron Microscope (SEM) testing

The SB powder, V250 powder, nano alumina, and # 1 aluminum sol used in the comparative example were subjected to Scanning Electron Microscope (SEM) tests, and the results are shown in fig. 1 to 4, respectively. SEM images show that the SB powder particles are nearly spherical, have a broad particle size distribution, have a particle size range of about 5-250 μm, have an average particle size of about 150 μm, and have a dense surface. The V250 powder particles are also approximately spherical, have wider particle size and loose surface porosity. The nano alumina has narrow particle size distribution and small particle size below 20 microns. The No. 1 aluminum sol has irregular shape, small particle size and certain agglomeration effect, and the particle size is about 5-20 nm.

Test example 2: NH (NH)₃Measurement of catalyst acid amount in stages by TPD

The total acid density of the molecular sieve was determined using a Chemstar TPx temperature programmed desorption apparatus from kanta corporation.0.15g of each of the catalysts in examples and comparative examples was weighed and placed in a sample tube. Firstly, taking Ar gas as carrier gas, heating to 550 ℃, and purging for 120min to remove impurities adsorbed on the surface of the catalyst. The temperature is reduced to 100 ℃, and NH is adsorbed in a saturated way₃Post-purging of mixed gas of-He to remove physisorbed NH₃Heating to 250 deg.C, 350 deg.C, 450 deg.C and 550 deg.C to remove chemisorbed NH at different temperatures₃The acid at 250 ℃ is weak acid, the acid at 350 ℃ and 450 ℃ is medium strong acid, and the acid at 550 ℃ is strong acid. And the respective amounts of acids of the catalysts in examples and comparative examples were measured in this way and are shown in table 1.

The acid amounts of the Y molecular sieve, the ZSM-5 molecular sieve, the MCM-22 molecular sieve, the beta molecular sieve, the MOR molecular sieve and the MCM-41 molecular sieve are respectively measured by adopting the method, and the acid amount promotion percentage of each catalyst in the example and the comparative example is calculated according to the acid amount of each molecular sieve compared with the corresponding pure molecular sieve and is listed in the table 2.

NH₃The TPD result shows that the molecular sieve is not modified and modified, only the grain diameter of the adopted alumina is changed, and NH of the alumina sol with smaller grain diameter is adopted₃The amount of TPD acid is about twice that of the catalyst with larger particle size, which shows that the invention can effectively increase the amount of the catalyst acid.

TABLE 1

Test example 3: carbon four alkylation reaction test

The catalysts of the above examples and comparative examples of the present disclosure were used in a carbotetralkylation reaction with a reaction raw material of isobutane-butene (isobutane to butene mass ratio 260, from beijing huayuan gas ltd.), a reaction temperature of 85 ℃ and a reaction pressure of 4.0 Mpa; the activity, selectivity and lifetime of the catalyst were tested by gas chromatography. The test results are shown in Table 2.

TABLE 2

As can be seen from the data in tables 1 and 2, the catalyst of the present disclosure can effectively increase the total acid amount of the catalyst at a smaller dosage by using the specific alumina sol with the particle size less than 20nm, and when the catalyst is used for the carbon four-alkylation reaction, the conversion rate, the selectivity and the catalyst life are all obviously improved.

The preferred embodiments of the present disclosure have been described above in detail, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications are within the protective scope of the present disclosure.

It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims

1. A high acid catalyst, characterized in that the catalyst comprises a molecular sieve and an aluminum sol, the weight ratio of the molecular sieve to the aluminum sol on a dry basis being from 99:1 to 20: 80; the average particle size of the aluminum sol is less than 20 nm.

2. The high acid catalyst of claim 1, wherein the weight ratio of the molecular sieve to the aluminum sol on a dry basis is from 95:5 to 25:75, preferably from 90:10 to 50: 50.

3. The high acid catalyst of claim 2, wherein the alumina sol has an average particle size of less than 15 nm.

4. The high acid catalyst according to claim 1, wherein the alumina sol has a pH of 1 to 5 and a concentration of 0.1 to 50 wt%.

5. The high acid catalyst according to claim 1, wherein the molecular sieve has an average particle diameter of 0.01 to 50 μm and a silicon-aluminum atomic ratio of 1 to 1000.

6. The high acid catalyst of claim 1, wherein the molecular sieve is a hydrogen type molecular sieve, and the hydrogen type molecular sieve is one or more of an X type molecular sieve, a Y type molecular sieve, a beta type molecular sieve, a ZSM-5 type molecular sieve, an MCM-22 type molecular sieve, an MCM-41 type molecular sieve, and a mordenite type molecular sieve.

7. The high acid catalyst of any of claims 1-6, wherein NH is used₃-the ratio of the total acid amount of the catalyst to the total acid amount of the molecular sieve as measured by the TPD method is 1.5 or more.

8. A method of preparing a high acid catalyst, comprising: mixing a molecular sieve, alumina sol, acid and water to obtain a mixed material, and forming the mixed material to obtain a catalyst precursor; wherein the dosage ratio of the molecular sieve to the aluminum sol is 99:1 to 20:80 based on dry weight, and the average particle size of the aluminum sol is less than 20 nm.

9. The method of claim 8, wherein the aluminum sol has an average particle size of less than 15 nm; the pH of the aluminum sol is 1-5, and the concentration is 0.1-50 wt%.

10. The process according to claim 8 or 9, wherein the molecular sieve and the aluminium sol are used in a ratio of 95:5 to 25:75, preferably 90:10 to 50:50, on a dry weight basis.

11. The method of claim 8, wherein the acid is one or more of hydrochloric acid, nitric acid, oxalic acid and citric acid; the acid is added in the form of an acid solution, and the concentration of the acid solution is 1-10 wt%.

12. The method of claim 8, wherein the method further comprises: drying and/or roasting the catalyst precursor to obtain the high-acid-content catalyst; the drying conditions are such that the dried catalyst has a dry weight of 60% or more; the roasting conditions comprise: the roasting temperature is 450-650 ℃, and the roasting time is 1-6 h.

13. The method of claim 8, wherein the method further comprises: adding a lubricant and/or a pore-forming agent into the mixed material, wherein the lubricant is selected from one or more of sesbania powder, methyl cellulose, polyether, polyvinyl alcohol, chitosan and cyclodextrin; the pore-forming agent is selected from one or more of sesbania powder, methyl cellulose, polyether, polyvinyl alcohol, chitosan and cyclodextrin; the amount of the lubricant is 0-0.3 part by weight and the amount of the pore-forming agent is 0-0.3 part by weight relative to 1 part by weight of the molecular sieve on a dry basis.

14. The method according to claim 8, wherein the molecular sieve has an average particle diameter of 0.01 to 50 μm and a silicon-aluminum atomic ratio of 1 to 1000.

15. The method according to claim 8, wherein the molecular sieve is a hydrogen type molecular sieve, and the hydrogen type molecular sieve is one or more of an X type molecular sieve, a Y type molecular sieve, a beta type molecular sieve, a ZSM-5 type molecular sieve, an MCM-22 type molecular sieve, an MCM-41 type molecular sieve and a mordenite type molecular sieve.

16. A high acid catalyst prepared by the process of any one of claims 8 to 15.

17. A method for conducting a carbotetraalkylation reaction, the method comprising: contacting a high acid content catalyst according to any one of claims 1 to 7 and claim 16 with a carbon four feedstock under alkylation reaction conditions.

18. The process of claim 17, wherein the alkylation reaction conditions comprise: the reaction temperature is 30-100 ℃, and the reaction pressure is 0.5-6 MPa; the carbon four feedstock comprises isobutane and butenes.