CN111744491A

CN111744491A - Modified alumina, preparation method of modified alumina and catalyst containing modified alumina

Info

Publication number: CN111744491A
Application number: CN201910247444.8A
Authority: CN
Inventors: 田辉平; 张杰潇; 李家兴; 许明德; 张万虹; 严加松
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: 2019-03-29
Filing date: 2019-03-29
Publication date: 2020-10-09
Anticipated expiration: 2039-03-29
Also published as: CN111744491B

Abstract

The invention provides modified alumina, a preparation method of the modified alumina and a catalyst containing the modified alumina. The preparation method comprises the following steps: aging the raw material mixture to obtain a first precursor; carrying out ion exchange on the first precursor and a rare earth compound to obtain a second precursor; roasting the second precursor to prepare the modified alumina; wherein the raw material mixture comprises a first aluminum source, a second aluminum source, a pore-expanding agent and water, the first aluminum source comprises Al (OH), the second aluminum source comprises Al (OH)₃. The modified alumina of one embodiment of the invention has an optimized pore structure and is used for a catalytic cracking catalystThe catalyst can keep higher heavy metal pollution resistance, higher cracking performance and better product distribution on the basis of having lower content of the active component molecular sieve.

Description

Modified alumina, preparation method of modified alumina and catalyst containing modified alumina

Technical Field

The invention relates to alumina, in particular to modified alumina with an optimized pore structure and application thereof.

Background

With the trend of petroleum resource development towards heaviness and deterioration, how to reasonably utilize inferior residual oil is a difficult problem in the oil refining industry, and particularly, how to improve the refining effect of the inferior residual oil is the most important thing when a catalytic cracking process is used as the basis of an oil refining process.

In China, a catalytic cracking unit (FCCU) is always the most important crude oil secondary processing device in oil refining enterprises due to the advantages of strong adaptability to raw materials, high yield of light oil products, high gasoline octane number and the like. At present, a catalytic cracking device bears the production tasks of 75% of gasoline, 35% of diesel oil, propylene, ethylene and other chemical products in China, so that a catalytic cracking technology is the key point of oil refining in China, and the core technology of the catalytic cracking technology depends on the performance of a catalyst. After crude oil is degraded, residual oil contains high impurities such as heavy metal, S, N, carbon residue and the like, which cause great toxic pollution to a catalytic cracking catalyst, so that the performance of the catalyst is reduced, the product distribution of a catalytic cracking unit is influenced, and the oil refining yield is greatly influenced.

The traditional FCC catalyst generally consists of a substrate and a molecular sieve, wherein the molecular sieve is a catalyst active center, and the catalyst is required to have higher reaction activity, more macroporous structures and more excellent pore structure distribution in order to improve the heavy oil conversion capability of the FCC catalyst, so that the development requirement cannot be completely met by simply increasing the content of active components, and simultaneously, the excessive active components can cause the excessive coke yield in the product distribution and influence the material, heat and benefit balance of a catalytic cracking device. Therefore, improvement of the heavy oil conversion ability of the catalyst by improving the substrate performance is an important research direction in the future.

Disclosure of Invention

One of the main objects of the present invention is to provide a method for preparing modified alumina, comprising:

aging the raw material mixture to obtain a first precursor;

carrying out ion exchange on the first precursor and a rare earth compound to obtain a second precursor; and

roasting the second precursor to prepare the modified alumina;

wherein the raw material mixture comprises a first aluminum source, a second aluminum source, a pore-expanding agent and water, the first aluminum source comprises Al (OH), the second aluminum source comprises Al (OH)₃。

According to an embodiment of the invention, the molar ratio of the first aluminum source, the second aluminum source, the pore-expanding agent and the water is (1-4): 10-40, and the molar numbers of the first aluminum source and the second aluminum source are calculated by alumina.

According to an embodiment of the invention, the first aluminium source is selected from pseudoboehmite and/or boehmite; the second aluminum source is selected from one or more of gibbsite, bayerite, noralite and aluminum hydroxide.

According to one embodiment of the present invention, the raw material mixture is subjected to the aging treatment at a temperature of 100 to 200 ℃, and then to the drying treatment at a temperature of not more than 200 ℃; and roasting the second precursor at the temperature of 500-1000 ℃.

According to an embodiment of the invention, the pore-expanding agent is selected from one or more of ammonium bicarbonate, activated carbon, EDTA, n-butylamine, polyacrylamide, n-butanol, citric acid.

According to an embodiment of the invention, the rare earth compound is selected from one or more of the sulfates, nitrates, hydrochlorides of rare earth elements.

An embodiment of the present invention provides a modified alumina having a crystalline phase structure of γ -alumina, wherein, based on a total volume of pores having a pore diameter D of 2 to 100nm, a volume of pores having a pore diameter D of 2nm or more and 5nm or less accounts for 0 to 10%, a volume of pores having a pore diameter D of 5nm or more and 10nm or less accounts for 10 to 25%, and a volume of pores having a pore diameter D of 10nm or more and 100nm or less accounts for 65 to 90%.

According to an embodiment of the present invention, the modified alumina has a specific surface area of 200 to 300m²The total pore volume is 0.35-0.45 ml/g.

According to an embodiment of the present invention, the volume of pores with a pore diameter of 10. ltoreq. D < 20nm is 0.06-0.10 ml/g, the volume of pores with a pore diameter of 20. ltoreq. D < 30nm is 0.06-0.09 ml/g, the volume of pores with a pore diameter of 30. ltoreq. D < 40nm is 0.02-0.04 ml/g, and the volume of pores with a pore diameter of 40. ltoreq. D < 50nm is 0.02-0.03 ml/g.

According to an embodiment of the present invention, Al of the modified alumina₂O₃The content of Re is not less than 90 wt%₂O₃Is not more than 5 wt%, based on the total weight of the modified alumina.

According to one embodiment of the present invention, the ratio of the B acid to the L acid in the modified alumina is (0.1-1): 1.

According to an embodiment of the present invention, the amount of the B acid in the modified alumina is 5 to 20. mu. mol^-1The amount of L acid is 20 to 50. mu. mol^-1。

An embodiment of the present invention provides a catalyst comprising the above modified alumina.

According to an embodiment of the present invention, the catalyst comprises 25 to 50 wt% of a molecular sieve, 0 to 50 wt% of clay, 10 to 30 wt% of a binder, and 2 to 30 wt% of the modified alumina, based on the total weight of the catalyst.

The modified alumina provided by the embodiment of the invention has an optimized pore structure, is used for a catalytic cracking catalyst, and can keep higher heavy metal pollution resistance, higher cracking performance and better product distribution on the basis of lower active component molecular sieve content of the catalyst.

Detailed Description

Exemplary embodiments that embody features and advantages of the invention are described in detail below in the specification. It is to be understood that the invention is capable of modification in various embodiments without departing from the scope of the invention, and that the description is intended to be illustrative in nature and not to limit the invention.

An embodiment of the present invention provides a method for preparing modified alumina, including:

aging the raw material mixture to obtain a first precursor;

roasting the second precursor to prepare the modified alumina;

wherein the raw material mixture comprises a first aluminum source, a second aluminum source, a pore-expanding agent and water, the first aluminum source comprises Al (OH), for example, the first aluminum source can be boehmite (AlO (OH)); the second aluminum source comprises Al (OH)₃。

In one embodiment, the molar ratio of the first aluminum source, the second aluminum source, the pore-expanding agent and the water is (1-4): 10-40, preferably (1-1.5): 10-15, such as 1:2:1:10, 2:1:1:10, 1:1:1:15, etc. Wherein the mole numbers of the first aluminum source and the second aluminum source are calculated by aluminum oxide.

In one embodiment, the solid component of the first aluminum source is Al₂O₃Not less than 95% of Fe₂O₃0.1-1.5% of Na₂O content of 0.01-1%, SiO₂The content is 0.1-1.5%; the above contents are all weight contents, and the contents of the components are based on the total solid weight of the first aluminum source.

In one embodiment, the solid component of the second aluminum source is Al₂O₃Not less than 95% of Fe₂O₃The content is 0.1-1.5%,Na₂o content of 0.1-1%, SiO₂The content is 0.1-1.5%; the contents are weight contents, and the contents of the components are based on the total solid weight of the second aluminum source.

In one embodiment, the first aluminum source may be pseudoboehmite and/or boehmite.

In one embodiment, the second aluminum source may be gibbsite, bayerite, noralite, aluminum hydroxide, or the like; the aluminum hydroxide may be amorphous aluminum hydroxide, and is prepared by reacting soluble aluminum salt with alkali, such as aluminum sulfate and sodium hydroxide.

In one embodiment, the pore-expanding agent may be one or more of ammonium bicarbonate, activated carbon, EDTA, n-butylamine, polyacrylamide, n-butanol, citric acid; preferably one or more of ammonium bicarbonate, activated carbon and citric acid.

In one embodiment, the mixture is aged at 100-200 ℃ under steam for 2-5 h, such as 3 h. Preferably, the temperature of the aging treatment of the mixture is 110 to 180 ℃, more preferably 120 to 150 ℃, for example 130 ℃, 140 ℃, 170 ℃, 190 ℃ and the like.

In one embodiment, the aged solid is dried under optional conditions to produce the first precursor.

In one embodiment, the temperature of the drying process may be not more than 200 ℃, and further, the temperature of the drying process may be 100 to 140 ℃, for example, 120 ℃ or 130 ℃.

In one embodiment, the solid component of the first precursor is Al₂O₃Not less than 95% of Fe₂O₃0.01-1.5% of Na₂O content of 0.01-1%, SiO₂The content is 0.01-1.5%; the contents are weight contents, and the contents of the components are based on the total solid weight of the first precursor.

In one embodiment, the specific surface area of the first precursor may be 300-380 m²The pore volume is 0.25-0.35 ml/g.

In one embodiment, the first precursor is mixed with a rare earth compound at 40-80 ℃, and the mixture is stirred for exchange treatment and dried to obtain a second precursor; wherein the exchange temperature (mixing temperature) can be 50 deg.C, 60 deg.C, 70 deg.C, etc.; the exchange time can be 0.5-2 h, such as 1h and 1.5 h; the drying temperature may be 120 ℃.

In one embodiment, the rare earth compound (as RE)₂O₃In terms of alumina) and the first precursor (in terms of alumina) may be (0.01 to 0.05):1, and may further be (0.01 to 0.03):1, for example, 0.02:1, 0.03:1, 0.04:1, and the like.

In one embodiment, the rare earth compound may be a sulfate, a nitrate, a hydrochloride, or the like of a rare earth element, wherein the rare earth element may be one or more of La, Ce, Pr, and Nd, preferably La and Ce.

In one embodiment, the second precursor is baked at 500-1000 ℃ for 2-6 h, and further the baking temperature may be 500-700 ℃, such as 600 ℃, 650 ℃, 750 ℃, 800 ℃ and the like; the roasting time may be 2.5 to 5 hours, and further may be 3 to 4 hours.

The preparation method of the modified alumina of one embodiment of the present invention comprises:

uniformly mixing a first aluminum source, a second aluminum source, a pore-expanding agent and water according to the molar ratio of (1-4) to (10-40);

aging the raw material mixture under the condition of steam of 100-200 ℃ for 2-5 h, and drying the obtained solid at the temperature of not more than 200 ℃ to obtain a first precursor;

carrying out exchange treatment on the obtained first precursor and a rare earth compound at the temperature of 40-80 ℃ for 0.5-2 h to obtain a second precursor;

and roasting the second precursor at 500-1000 ℃ for 2-6 hours to prepare the modified alumina.

In one embodiment, the prepared modified alumina has a crystalline phase structure of γ -alumina, and the volume of pores with a pore diameter D of 2nm or more and D of 5nm or less is 0 to 10%, such as 1%, 5%, 9%, etc., based on the total volume of pores with a pore diameter D of 2 to 100 nm; the volume of the pores with the pore diameter of 5 < D < 10nm accounts for 10-25%, such as 15%, 20%, 22% and the like; the volume of the pores with the pore diameter of 10 < D < 100nm accounts for 65-90%, such as 70%, 75%, 80%, 85% and the like.

In one embodiment, the crystallinity of the gamma-alumina is 40 to 60%, for example, 45%, 50%, 55%, etc.

In one embodiment, the modified alumina has a specific surface area of 200-300 m²G, e.g. 220m²/g、250m²/g、260m²/g、265m²/g、280m²And/g, etc.

In one embodiment, the modified alumina has a total pore volume of 0.35 to 0.45ml/g, e.g., 0.37ml/g, 0.38ml/g, 0.40ml/g, 0.42ml/g, and the like.

In one embodiment, the modified alumina has a pore volume of 0.30 to 0.40ml/g, for example, 0.32ml/g, 0.34ml/g, 0.35ml/g, 0.37ml/g, etc., for pores having a pore diameter of 2 to 100 nm.

In one embodiment, the modified alumina has a pore volume of 0.06-0.10 ml/g for pores with a pore diameter of 10. ltoreq. D < 20nm, a pore volume of 0.06-0.09 ml/g for pores with a pore diameter of 20. ltoreq. D < 30nm, a pore volume of 0.02-0.04 ml/g for pores with a pore diameter of 30. ltoreq. D < 40nm, and a pore volume of 0.02-0.03 ml/g for pores with a pore diameter of 40. ltoreq. D < 50 nm.

In one embodiment, the modified alumina may have a pore diameter of 6 to 30nm, preferably 6 to 20nm, for example, 10nm, 12nm, 15nm, etc.

In the modified alumina of one embodiment, the ratio of the B acid (Bronsted acid) to the L acid (Lewis acid) may be (0.1 to 1):1, and may be (0.25 to 0.40):1, for example, 0.3:1, 0.35:1, 0.45:1, 0.5:1, and the like.

In one embodiment, the modified alumina has an acid B content of 5 to 20. mu. mol^-1E.g. 8. mu. mol.g^-1、10μmol.g^-1、15μmol.g^-1、18μmol.g^-1And the amount of L acid is 20 to 50 mu mol^-1E.g. 30. mu. mol.g^-1、35μmol.g^-1、40μmol.g^-1、45μmol.g^-1And the like.

In one embodiment of the modified alumina, Al₂O₃The content of (b) is not less than 90 wt%, may be 90 to 99 wt%, and further may be 90 to 95 wt%, for example 94%, 98%, etc., wherein the content of each component in the modified alumina is based on the total weight of the modified alumina.

In one embodiment of the modified alumina, Re₂O₃The content of (B) is not more than 5 wt%, and may be 0.05 to 5 wt%, for example, 1%, 2%, 2.5%, 2.7%, 3%, 3.5%, 4%, 4.5%, etc.

In one embodiment of the modified alumina, Fe₂O₃The content of (B) is not more than 1.5 wt%, and may be 0.1 to 0.5 wt%, for example, 0.2%, 0.25%, 0.3%, 0.4%, 1.0%, 1.2%, etc.

In one embodiment of the modified alumina, Na₂The content of O is not more than 1 wt%, and may be 0.01 to 0.5 wt%, for example, 0.04%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.8%, etc.

In one embodiment of the modified alumina, SiO₂The content of (A) is not more than 1.5 wt%, and may be 0.1 to 0.5 wt%, or not more than 0.3 wt%, for example, 0.2%, 0.25%, 0.3%, 0.4%, 1.0%, 1.2%, etc.

One embodiment of the present invention provides a modified alumina, particularly a modified alumina modified by rare earth elements and having an optimized pore structure, for use in a catalytic cracking catalyst.

One embodiment of the present invention provides a catalyst, in particular a catalytic cracking catalyst, comprising a modified alumina matrix as described above.

The catalyst of the embodiment of the invention can still keep higher heavy metal pollution resistance, higher cracking activity and better product distribution on the premise of reducing the molecular sieve serving as an active component.

In one embodiment, the catalyst comprises a molecular sieve, clay, binder, and a modified alumina matrix.

In the catalyst according to an embodiment of the present invention, the content of the modified alumina may be 2 to 30 wt%, and further may be 5 to 15 wt%, for example, 10 wt%, 20 wt%, 25 wt%, or the like; wherein, the contents of the components in the catalyst are calculated by dry weight (800 ℃, the weight after 1 hour of roasting), and the total weight of the catalyst is used as a reference.

In the catalyst according to an embodiment of the present invention, the content of the molecular sieve is 25 wt% or more, and may be 25 to 50 wt%, and further may be 25 to 35 wt%, for example, 27 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or the like.

In the catalyst according to an embodiment of the present invention, the clay content may be 0 to 50 wt%, and further 0 to 30 wt%, for example, 5 wt%, 10 wt%, 25 wt%, 30 wt%, 40 wt%, 45 wt%, or the like.

In the catalyst of one embodiment of the present invention, alumina binder (as Al)₂O₃In terms of the total amount of the components) may be 10 to 30 wt%, and further 15 to 26 wt%, for example, 20 wt%, 25 wt%, or the like.

The molecular sieves of the present invention are not limited in kind, and any molecular sieve commonly used in the art may be used in the present invention, and examples thereof include REY, REHY, REUSY, USY, and SiCl₄Al removal and Si supplement method), liquid phase chemical method ((NH)₄)₂SiF₆Aluminum extraction and silicon supplement) and other methods, and ZSM-5 type and β type zeolites with other high silica-alumina ratio or their mixture.

The present invention is not limited to the kind of clay, and commonly used clays may be used in the present invention, for example, one or more of kaolin, halloysite, montmorillonite, diatomaceous earth, halloysite, pseudohalloysite, saponite, rectorite, sepiolite, attapulgite, hydrotalcite and bentonite, preferably kaolin and/or halloysite.

The binder of the present invention is not limited in kind, and may be one or more of acidified pseudoboehmite and aluminum sol, silica sol, magnesium aluminum sol, zirconium sol, titanium sol, which are well known in the art, and preferably acidified pseudoboehmite and aluminum sol.

An embodiment of the present invention provides a method for preparing a catalyst, including:

pulping the binder, clay, molecular sieve and modified alumina to obtain catalyst slurry; and

and (4) carrying out spray drying on the catalyst slurry to obtain the catalyst.

In one embodiment, the catalyst slurry has a solids content of 30 wt% or more, preferably 30 to 40 wt%.

In the present invention, the specific surface area is determined by nitrogen cryosorption (BET method, see GB T58161995 catalyst and adsorbent surface area determination); the pore volume was determined by the dripping method (see RIPP28-90, methods for petrochemical analysis, scientific Press, 1990); measuring the element composition by using a fluorescence spectrometry; the phase and crystallinity data are measured by an X-ray diffraction method (see RIPP 141-90 gamma-alumina crystallinity measurement method); the acid data adopts an infrared pyridine adsorption in-situ measurement method, and the desorption temperature is 200 ℃. The measurement method is as follows:

the type of acid center and its acid amount were determined by infrared analysis using pyridine adsorption. An experimental instrument: model Bruker IFS113V FT-IR (fourier transform infrared) spectrometer, usa. Experimental method for measuring acid content at 200 ℃ by using pyridine adsorption infrared method: and (3) carrying out self-supporting tabletting on the sample, and placing the sample in an in-situ cell of an infrared spectrometer for sealing. Heating to 400 deg.C, and vacuumizing to 10 deg.C^- ³And Pa, keeping the temperature for 2h, and removing gas molecules adsorbed by the sample. The temperature is reduced to room temperature, pyridine vapor with the pressure of 2.67Pa is introduced to keep the adsorption equilibrium for 30 min. Then heating to 200 ℃, and vacuumizing to 10 DEG C^-3Desorbing for 30min under Pa, reducing to room temperature for spectrography, scanning wave number range: 1400cm^-1～1700cm^-1And obtaining the pyridine absorption infrared spectrogram of the sample desorbed at 200 ℃. According to pyridine absorption infrared spectrogram of 1540cm^-1And 1450cm^-1The strength of the adsorption peak is characterized to obtain the total content in the molecular sieve

Relative amount of acid center (B acid center) to Lewis acid center (L acid center).

The modified alumina, the preparation method thereof and the catalyst according to one embodiment of the present invention will be further described with reference to specific examples. The raw material specifications used in the examples are as follows:

kaolin: a solid content of 81.2 wt%, produced by Kaolin corporation of China (Suzhou);

citric acid, ammonium bicarbonate: analyzing and purifying;

aluminum sol: al (Al)₂O₃22 wt%, produced by Qilu Branch of China petrochemical catalyst, Inc.;

rare earth chloride mixed solution: the concentration is 328.46g/L, and the catalyst contains La and Ce (the molar ratio of La to Ce is 1:1) and is produced by Qilu division of China petrochemical catalyst Co., Ltd;

pseudo-boehmite: solid content 72 wt%, Shandong aluminum industries, China;

monohydrate of diaspore: pore volume is 0.82mL/g, specific surface area is 285m²(iv)/g, trihydrate content 3 wt%; on a dry basis, Al₂O₃Content 96 wt%, Na₂O content less than 0.1 wt%, and the product of Shandong mountain aluminum Yifeng aluminum-based New Material Co., Ltd, brand name P-DF-07-Lsi;

gibbsite: on a dry basis, Al₂O₃97 wt% of Fe₂O₃0.3 wt% of Na₂O content 0.4 wt%, SiO₂Content 0.3 wt%, Zibo Yao and Al industries Ltd;

REY type molecular sieve: produced by Qilu division of China petrochemical catalyst, Inc., and has a solid content of 80 wt%;

calculating and determining the components in the catalyst obtained by the application example according to the feeding amount of each raw material;

the composition analysis of each material was determined by XRF fluorescence analysis (RIPP 117-90 standard method (compiled by petrochemical analysis methods (RIPP test methods), Yangcui et al, published by scientific Press, 1990)).

The pore distribution of alumina is measured by the following method: the specific surface area of the cracking catalyst was determined according to GB/T5816-1995 using an Autosorb-1 nitrogen desorption apparatus from Congta, USA, and the sample was degassed at 300 ℃ for 6 hours before the test. The average pore size was calculated by the BJH model.

Example 1

The preparation method comprises the following steps of stirring and mixing the monohydrate bauxite, the gibbsite, the citric acid, the ammonium bicarbonate and the water for 1h according to the molar ratio of 1:1:0.5:0.5:10, aging the obtained mixture for 3h under the condition of water vapor at 130 ℃ and 1atm (absolute pressure, the same below), wherein the water vapor content in the atmosphere is 100% by volume, the same below, and drying the obtained solid at 120 ℃ in the air atmosphere to obtain the first precursor A.

Mixing a first precursor A (calculated by alumina) with a rare earth chloride mixed solution (calculated by RE)₂O₃Calculated) are mixed according to the molar ratio of 1:0.03, stirred for 1h at 60 ℃, then filtered, the filter cake is dried at 120 ℃, and the dried solid is roasted for 3h at 700 ℃ to finally obtain the modified alumina B modified by rare earth and optimized in pore structure. The results of the composition analysis and pore distribution of the first precursor a and the modified alumina B are shown in table 1.

Example 2

The preparation method comprises the steps of stirring and mixing monohydrate bauxite, gibbsite, citric acid, ammonium bicarbonate and water according to the molar ratio of 1:1:0.5:0.5:10 for 1h, aging the obtained mixture for 3h in an atmosphere of 1atm at 130 ℃ and 100% volume of water vapor, and drying the obtained solid in an atmosphere of 120 ℃ to obtain a first precursor A.

Mixing a first precursor A (calculated by alumina) with a rare earth chloride mixed solution (calculated by RE)₂O₃Calculated) are mixed according to the molar ratio of 1:0.03, stirred for 1h at 60 ℃, then filtered, a filter cake is dried at 120 ℃, and the dried solid is roasted for 3h at 500 ℃ to finally obtain the modified alumina C with the optimized pore structure, wherein the related analytical data are shown in Table 1.

Example 3

Stirring and mixing the monohydrate bauxite, the gibbsite, the n-butylamine and the water for 1h according to the molar ratio of 1:1:1:10, aging the obtained mixture for 3h in an atmosphere of 1atm at 130 ℃ and 100% volume of water vapor, drying the obtained solid in an atmosphere of 120 ℃ and mixing the dried solid with a rare earth chloride mixed solution (by using RE (rare earth) in an air atmosphere₂O₃Calculated) are mixed according to the molar ratio of 1:0.03, stirred for 1h at 60 ℃, then filtered, a filter cake is dried at 120 ℃, and the dried solid is roasted for 3h at 700 ℃ to finally obtain modified alumina D with an optimized pore structure, wherein relevant analytical data are shown in Table 1.

Example 4

Stirring and mixing the monohydrate bauxite, the gibbsite, the citric acid, the ammonium bicarbonate and the water according to the molar ratio of 1:1:0.5:0.5:10 for 1h, aging the obtained mixture for 3h in an atmosphere of 1atm at 130 ℃ and 100% volume of water vapor, drying the obtained solid in an atmosphere of 120 ℃ to obtain a first precursor A, and mixing the first precursor A with a rare earth chloride mixed solution (by using RE₂O₃Calculated) are mixed according to the molar ratio of 1:0.03, stirred for 1h at 60 ℃, then filtered, a filter cake is dried at 120 ℃, and the dried solid is roasted for 6h at 700 ℃ to finally obtain the modified alumina E with the optimized pore structure, wherein the related analytical data are shown in Table 1.

Example 5

The preparation method comprises the steps of stirring and mixing monohydrate bauxite, gibbsite, citric acid, ammonium bicarbonate and water according to the molar ratio of 1:4:0.5:0.5:10 for 1h, aging the obtained mixture for 3h in an atmosphere of 1atm at 130 ℃ and 100% volume of water vapor, and drying the obtained solid in an atmosphere of 120 ℃ to obtain a first precursor A.

Mixing a first precursor A (calculated by alumina) with a rare earth chloride mixed solution (calculated by RE)₂O₃Calculated) are mixed according to the molar ratio of 1:0.01, stirred for 1h at 60 ℃, then filtered, a filter cake is dried at 120 ℃, and the dried solid is roasted for 3h at 500 ℃ to finally obtain the modified alumina F with the optimized pore structure, wherein the related analytical data are shown in Table 1.

Example 6

The preparation method comprises the steps of stirring and mixing the monohydrate bauxite, the gibbsite, the citric acid, the ammonium bicarbonate and the water according to the molar ratio of 4:1:0.5:0.5:10 for 1 hour, aging the obtained mixture for 3 hours at 130 ℃ in an atmosphere of 1atm and 100% volume of water vapor, and drying the obtained solid at 120 ℃ in an atmosphere of air to obtain the first precursor A.

Mixing a first precursor A (calculated by alumina) with a rare earth chloride mixed solution (calculated by RE)₂O₃Calculated) are mixed according to the molar ratio of 1:0.05, stirred for 1h at 60 ℃, then filtered, a filter cake is dried at 120 ℃, and the dried solid is roasted for 3h at 500 ℃ to finally obtain the modified alumina G with the optimized pore structure, wherein the related analytical data are shown in Table 1.

Comparative example 1

Stirring and mixing monohydrate bauxite, gibbsite and water according to a molar ratio of 1:1:10 for 1h, aging the obtained mixture at 130 ℃ and 1atm of water vapor (water vapor 100%) for 3h, drying the obtained solid at 120 ℃ (under air atmosphere, the same way is adopted below), and mixing with a rare earth chloride mixed solution (by using RE₂O₃Calculated) are mixed according to the molar ratio of 1:0.03, stirred for 1H at 60 ℃, then filtered, a filter cake is dried at 120 ℃, and the dried solid is roasted for 3H at 700 ℃ to finally obtain modified alumina H with an optimized pore structure, wherein relevant analytical data are shown in Table 1.

Comparative example 2

Stirring and mixing the monohydrate bauxite, the gibbsite, the citric acid, the ammonium bicarbonate and the water for 1h according to the molar ratio of 1:1:0.5:0.5:10, drying the obtained mixture at 120 ℃, and mixing the dried mixture with a rare earth chloride mixed solution (by using RE₂O₃Calculated) are mixed according to the molar ratio of 1:0.03, stirred for 1h at 60 ℃, then filtered, a filter cake is dried at 120 ℃, and the dried solid is roasted for 3h at 700 ℃ to finally obtain modified alumina I with optimized pore structure, wherein relevant analytical data are shown in Table 1.

Comparative example 3

Stirring and mixing the monohydrate bauxite, the gibbsite, the glucose and the water for 1h according to the molar ratio of 1:1:1:10, aging the obtained mixture for 3h under the condition of 130 ℃ and 1atm of water vapor (water vapor 100%), drying the obtained solid at 120 ℃, and mixing the dried solid with a rare earth chloride mixed solution (by using RE as a raw material)₂O₃Calculated) are mixed according to the molar ratio of 1:0.03, stirred for 1h at 60 ℃, then filtered, a filter cake is dried at 120 ℃, and the dried solid is roasted for 3h at 700 ℃ to finally obtain modified alumina J with an optimized pore structure, wherein relevant analytical data are shown in Table 1.

Comparative example 4

The first precursor A obtained in example 1 is roasted at 700 ℃ for 3h to obtain modified alumina K with an optimized pore structure, and the related composition analysis and pore distribution results are shown in Table 1.

Comparative example 5

Stirring and mixing diaspore, citric acid, ammonium bicarbonate and water at a molar ratio of 2:0.5:0.5:10 for 1h, and steaming the obtained mixture at 130 deg.C and 1atmAging for 3 hr under the condition of water vapor 100%, oven drying the obtained solid at 120 deg.C, and mixing with rare earth chloride mixed solution (using RE₂O₃Calculated) are mixed according to the molar ratio of 1:0.03, stirred for 1h at 60 ℃, then filtered, a filter cake is dried at 120 ℃, and the dried solid is roasted for 6h at 700 ℃ to finally obtain the modified alumina L with the optimized pore structure, wherein the related analytical data are shown in Table 1.

Comparative example 6

Stirring and mixing gibbsite, citric acid, ammonium bicarbonate and water according to a molar ratio of 2:0.5:0.5:10 for 1h, aging the obtained mixture at 130 ℃ and 1atm of water vapor (water vapor 100%) for 3h, drying the obtained solid at 120 ℃, and mixing with a rare earth chloride mixed solution (by using RE₂O₃Calculated) are mixed according to the molar ratio of 1:0.03, stirred for 1h at 60 ℃, then filtered, a filter cake is dried at 120 ℃, and the dried solid is roasted for 6h at 700 ℃ to finally obtain the modified alumina M with the optimized pore structure, wherein the related analytical data are shown in Table 1.

Table 1 compositional analysis data

As can be seen from table 1, the sodium oxide content, the alumina content, the rare earth oxide content, the iron oxide content, the silicon oxide content, and the like in the first precursor a, the modified aluminas B to G were measured in terms of chemical composition, and the obtained data were good. Compared with the modified alumina of the comparative example, the prepared rare earth modified alumina B to G improves the acid content of B and the ratio of B/L acid on the premise of not changing the existing macroporous structure.

Application example 1

Adding 36.36Kg of alumina sol into a reaction kettle, stirring, adding 27.78Kg of pseudoboehmite (72% by weight of solid content, available from Shandong aluminum Co., Ltd.), adding 103.82Kg of decationized water (also called acid water), stirring for 40min, adding 5.20Kg of rare earth modified alumina B matrix and 39.41Kg of kaolin, stirring for 60min, adding 4Kg of hydrochloric acid with concentration of 31% by weight, and stirring for 30 min. Then, 116.7Kg of molecular sieve slurry (43.75 Kg of molecular sieve and 72.92Kg of decationized water) was added, stirred for 30min, and spray-dried to obtain catalyst microspheres.

And roasting the obtained catalyst microspheres for 1h at 500 ℃, washing twice, washing with decationized water with the weight being 8 times of the dry basis weight of the catalyst microspheres for each time, and drying at constant temperature of 120 ℃ for 2 hours to obtain a sample C1. The catalyst formulation and product properties are shown in table 2.

Application example 2

Adding 36.36Kg of alumina sol into a reaction kettle, stirring, adding 27.78Kg of pseudoboehmite (72% by weight of solid content, available from Shandong aluminum Co., Ltd.), adding 112.19Kg of decationized water (also called acid water), stirring for 40min, adding 10.41Kg of rare earth modified alumina B matrix and 38.18Kg of kaolin, stirring for 60min, adding 4Kg of hydrochloric acid with concentration of 31% by weight, and stirring for 30 min. Then, 103.3Kg of molecular sieve slurry (38.75 Kg of molecular sieve and 64.55Kg of decationized water) was added, stirred for 30min, and spray-dried to obtain catalyst microspheres.

And roasting the obtained catalyst microspheres for 1h at 500 ℃, washing twice, washing with decationized water with the weight being 8 times of the dry basis weight of the catalyst microspheres for each time, and drying at constant temperature of 120 ℃ for 2 hours to obtain a sample C2. The catalyst formulation and product properties are shown in table 2.

Application examples 3 to 7

The preparation method of the catalyst is the same as that of the application example 2, except that the rare earth modified alumina B substrate is changed into a rare earth alumina modified C substrate, a rare earth alumina modified D substrate, a rare earth alumina modified E substrate, a rare earth alumina modified F substrate and a rare earth alumina modified G substrate.

And roasting the obtained catalyst microspheres for 1h at 500 ℃, washing twice, washing with decationized water with the weight being 8 times of the dry basis weight of the catalyst microspheres for each time, and drying at constant temperature of 120 ℃ for 2 hours to obtain samples C3-C7. The catalyst formulation and product properties are shown in table 2.

Comparative application example 1

36.36Kg of alumina sol was added to the reaction vessel, followed by stirring, 27.78Kg of pseudoboehmite (72% by weight in terms of solid content, available from Shandong aluminum Co., Ltd.) was added, 102.92Kg of decationized water (also referred to as acid water) was added, 45.57Kg of the modified alumina H substrate prepared in comparative example 1 and kaolin were added under stirring for 40min, 4Kg of hydrochloric acid having a concentration of 31% by weight was added after stirring for 60min, and the mixture was stirred for 30 min. Then, 116.7Kg of molecular sieve slurry (43.75 Kg of molecular sieve and 72.92Kg of decationized water) was added, stirred for 30min, and spray-dried to obtain catalyst microspheres.

And roasting the obtained catalyst microspheres for 1h at 500 ℃, washing twice, washing with decationized water with the weight being 8 times of the dry basis weight of the catalyst microspheres for each time, and drying at constant temperature of 120 ℃ for 2 hours to obtain a sample D1. The catalyst formulation and product properties are shown in table 2.

Comparative application examples 2 to 6

The catalyst was prepared in the same manner as in comparative example 1 except that the modified alumina H substrate was changed to modified alumina I substrate, modified alumina J substrate, modified alumina K substrate, modified alumina L substrate, and modified alumina M substrate, respectively.

And roasting the obtained catalyst microspheres for 1h at 500 ℃, washing twice, washing with decationized water with the weight being 8 times of the dry basis weight of the catalyst microspheres for each time, and drying at constant temperature of 120 ℃ for 2 hours to obtain samples D2-D6. The catalyst formulation and product properties are shown in table 2.

TABLE 2

Catalyst evaluation

The cracking reaction performance of the catalysts of the application examples of the present invention and the catalysts of the comparative application examples were evaluated.

The physicochemical property data of the feed oil are shown in Table 3.

Table 4 lists the results of the evaluations on the fixed fluidized bed apparatus. The catalyst is aged and deactivated by 100 percent of water vapor at 800 ℃ for 17 hours, the loading of the catalyst is 9g, the catalyst-oil ratio is 5 (weight ratio), and the reaction temperature is 500 ℃.

Wherein, the conversion rate is gasoline yield, liquefied gas yield, dry gas yield and coke yield

Yield of light oil is gasoline yield and diesel oil yield

Liquid yield is liquefied gas, gasoline and diesel oil

Coke selectivity-coke yield/conversion

TABLE 3

TABLE 4

The data in table 4 show that the catalyst prepared from the alumina substrate modified by the rare earth element and having the optimized pore structure, prepared by the embodiment of the present invention, has better heavy oil cracking capability and higher conversion rate, higher gasoline yield, lower heavy oil yield, higher light oil yield and good coke selectivity under the premise of the same amount of the molecular sieve, compared with the catalyst of the comparative application example; as can be seen from application examples 2-7 of the molecular sieve with lower content, the prepared catalysts C2-C7 still have better and better heavy oil cracking performance, higher conversion rate and higher gasoline yield compared with the comparative examples.

Catalysts C1-C7 and D1-D6 were subjected to cyclic contamination (to deposit Ni and V) on a cyclic aging apparatus, and the Ni and V contents on the cyclically contaminated catalyst mixture are shown in Table 5,

the step of circulating pollution comprises the following steps: introducing heavy metals (Ni and V) into the catalyst mixture by a Michelle impregnation method, then filling the catalyst material after introducing the heavy metals into a small fixed fluidized bed, and processing on a small fixed fluidized bed device according to the following steps:

(a) heating to 600 ℃ at a heating rate of 20 ℃/min in a nitrogen atmosphere;

(b) heating to 780 ℃ at the heating rate of 1.5 ℃/min, keeping the temperature at 780 ℃, and changing the treatment atmosphere according to the following steps in the constant temperature process;

(i) treating the mixture in an atmosphere containing 40 vol% of nitrogen (wherein the nitrogen contains 5 vol% of propylene) and 60 vol% of water vapor for 10 minutes;

(ii) treating for 10 minutes in an atmosphere containing 40% by volume of nitrogen (pure nitrogen, no propylene), 60% by volume of water vapor;

(iii) treated with an atmosphere containing 40% by volume of air (containing 4000ppm SO2), 60% by volume of water vapor for 10 minutes;

(iv) treating for 10 minutes in an atmosphere containing 40 vol% nitrogen and 60 vol% water vapor; then repeating the steps (i) - (iv) once more in the aforementioned order, and then repeating the step (i) to finish the cyclic contamination step;

then aging is carried out: aging the circularly contaminated catalyst mixture at 800 ℃ for 8 hours in an atmosphere containing 100 vol% of water vapor;

then, observing the catalytic performance of the catalyst mixture subjected to cyclic pollution-aging on an ACE device; wherein, the raw oil (properties are shown in Table 3) enters into contact with the catalyst mixture at the bottom of the reactor, and the specific evaluation conditions and results are shown in Table 5.

TABLE 5

The data in table 5 show that the catalyst prepared by using the alumina modified by rare earth and having an optimized pore structure prepared by the method of the embodiment of the present invention has better metal contamination resistance, and the cracking activity is reduced compared with the activity of an uncontaminated fresh agent, but still has better cracking activity compared with the catalyst of the comparative application example, and simultaneously has higher conversion rate and gasoline yield compared with the contaminated comparative agent.

Unless otherwise defined, all terms used herein have the meanings commonly understood by those skilled in the art.

The described embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of the present invention, and those skilled in the art may make various other substitutions, alterations, and modifications within the scope of the present invention, and thus, the present invention is not limited to the above-described embodiments but only by the claims.

Claims

1. A method for preparing modified alumina, comprising:

aging the raw material mixture to obtain a first precursor;

roasting the second precursor to prepare the modified alumina;

2. The method of claim 1, wherein the molar ratio of the first aluminum source, the second aluminum source, the pore-expanding agent and the water is (1-4): 1-4: (10-40), and the molar numbers of the first aluminum source and the second aluminum source are calculated by aluminum oxide.

3. The process of claim 1 wherein the first aluminum source is selected from pseudoboehmite and/or boehmite; the second aluminum source is selected from one or more of gibbsite, bayerite, noralite and aluminum hydroxide.

4. The method according to claim 1, wherein the raw material mixture is subjected to the aging treatment at a temperature of 100 to 200 ℃ and then to the drying treatment at a temperature of not more than 200 ℃; and roasting the second precursor at the temperature of 500-1000 ℃.

5. The method of claim 1, wherein the pore-expanding agent is selected from one or more of ammonium bicarbonate, activated carbon, EDTA, n-butylamine, polyacrylamide, n-butanol, citric acid.

6. The method of claim 1, wherein the rare earth compound is selected from one or more of a sulfate, a nitrate, and a hydrochloride salt of a rare earth element.

7. The modified alumina has a crystalline phase structure of gamma-alumina, and based on the total volume of pores with the pore diameter D of 2-100 nm, the volume of the pores with the pore diameter D of 2-5 nm accounts for 0-10%, the volume of the pores with the pore diameter D of 5-10 nm accounts for 10-25%, and the volume of the pores with the pore diameter D of 10-100 nm accounts for 65-90%.

8. The modified alumina according to claim 7, having a specific surface area of 200 to 300m²The total pore volume is 0.35-0.45 ml/g.

9. The modified alumina according to claim 7, wherein the volume of pores having a pore diameter of 10. ltoreq. D < 20nm is 0.06 to 0.10ml/g, the volume of pores having a pore diameter of 20. ltoreq. D < 30nm is 0.06 to 0.09ml/g, the volume of pores having a pore diameter of 30. ltoreq. D < 40nm is 0.02 to 0.04ml/g, and the volume of pores having a pore diameter of 40. ltoreq. D < 50nm is 0.02 to 0.03 ml/g.

10. The modified alumina of claim 7, wherein Al₂O₃The content of Re is not less than 90 wt%₂O₃Is not more than 5 wt%, based on the total weight of the modified alumina.

11. The modified alumina according to claim 7, wherein the ratio of the B acid to the L acid is (0.1 to 1): 1.

12. The modified alumina of claim 7, wherein the amount of B acid is 5 to 20. mu. mol.g^-1The amount of L acid is 20 to 50. mu. mol^-1。

13. A catalyst comprising the modified alumina of any one of claims 1 to 12.

14. The catalyst of claim 13, comprising 25 to 50 wt% of a molecular sieve, 0 to 50 wt% of a clay, 10 to 30 wt% of a binder, and 2 to 30 wt% of the modified alumina, based on the total weight of the catalyst.