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CN115215360A - Method for improving load capacity of pseudo-boehmite supported catalyst - Google Patents

Method for improving load capacity of pseudo-boehmite supported catalyst Download PDF

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Publication number
CN115215360A
CN115215360A CN202210883307.5A CN202210883307A CN115215360A CN 115215360 A CN115215360 A CN 115215360A CN 202210883307 A CN202210883307 A CN 202210883307A CN 115215360 A CN115215360 A CN 115215360A
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boehmite
pseudo
additive
temperature
supported catalyst
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CN115215360B (en
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郭林明
郭铭忠
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Hangzhou Zhihuajie Technology Co ltd
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Hangzhou Zhihuajie Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/30—Preparation of aluminium oxide or hydroxide by thermal decomposition or by hydrolysis or oxidation of aluminium compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/02—Boron or aluminium; Oxides or hydroxides thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/44—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water
    • C01F7/441—Dehydration of aluminium oxide or hydroxide, i.e. all conversions of one form into another involving a loss of water by calcination
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids

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  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Abstract

The invention provides a method for improving the loading capacity of a pseudo-boehmite supported catalyst, which comprises the following steps: s1, adding an aluminum salt and a first additive into a mixed solvent to obtain a mixed solution A; s2.50 ℃, dropwise adding an oxalic acid solution into the mixed solution A obtained in the S1 for three times under magnetic stirring to obtain sol; s3, dissolving aluminum hydroxide in water, adding a second additive, and continuously stirring to obtain a mixed solution B; s4, drying the sol supercritical fluid obtained in the step S2 into powder, adding the powder into the mixed solution B obtained in the step S3, uniformly stirring, and placing the solution into a reaction kettle for hydrothermal reaction to obtain a reaction product; s5, centrifuging, washing and calcining the reaction product obtained in the step S4 to obtain pseudo-boehmite; the invention obtainsThe specific surface area of boehmite is not less than 400m 2 (ii)/g, the pore diameter shrinkage at high temperature is within 5%.

Description

Method for improving load capacity of pseudo-boehmite supported catalyst
Technical Field
The invention belongs to the field of fine chemical synthesis, and particularly relates to a method for improving the loading capacity of a pseudo-boehmite supported catalyst.
Background
Pseudoboehmite (pseudoboehmite) is a chemical alumina with uncertain composition, incomplete crystallization and thus controllable properties, and has the chemical formula of gamma-AlOOH.nH 2 O (n =0.08 to 0.62). It is non-toxic, tasteless, white colloid (wet product) or powder (dry powder), has reticular space structure, large gap, developed specific surface area, and thixotropy in acidic environmentSex, etc. Currently, in the field of petrochemical industry, activated alumina is used as a catalyst carrier, and most of the activated alumina is obtained by calcining pseudo-boehmite, so that the morphology and the specific surface area of the alumina are determined by the morphology and the particle size of the pseudo-boehmite.
Pseudo-boehmite as a raw material of an alumina catalyst carrier is generally prepared by the following method: (1) The alkaline precipitation method, i.e. the acidified aluminum salt is neutralized with alkali, alumina monohydrate is precipitated from the acidified aluminum salt solution by alkali, and then the pseudoboehmite product is obtained through the processes of aging, washing, calcining and the like, and the method is often called alkaline precipitation (acid method), such as the method of neutralizing aluminum trichloride with ammonia water; (2) Acid precipitation, i.e. neutralization of aluminate with strong acid or aluminium salt of strong acid, precipitation of alumina monohydrate from aluminate solution with acid, aging, washing, calcining to obtain pseudoboehmite, commonly called acid precipitation (alkaline process), such as CO 2 A method for neutralizing sodium metaaluminate with gas or aluminum sulfate; (3) The alkoxy aluminum hydrolysis method is to hydrolyze alkoxy aluminum and water to generate monohydrate alumina, and then to age, filter and dry to obtain the pseudo-boehmite product. Therefore, the preparation process of the pseudo-boehmite generally comprises the processes of grain generation (neutralization precipitation or hydrolysis process), grain growth (aging process), washing, calcination and the like. Therefore, the process conditions of grain generation and grain growth can influence the quantity and growth speed of the generated grains, and various preparation processes of the pseudoboehmite provide respective process conditions and improved methods so as to achieve the aim of controlling physical properties such as pore volume, specific surface area and the like of products.
Specifically, for example, patent CN 103787387B discloses a method for preparing pseudoboehmite, which uses gluconic acid and alkali metal salt of gluconic acid to improve the stability of sodium metaaluminate solution, so as to prolong the stability time of sodium metaaluminate solution, and the specific surface area of the prepared pseudoboehmite can reach 315m at most 2 (ii) in terms of/g. For another example, CN1861524 discloses a process for preparing pseudo-boehmite, which comprises adding 6-18 g of melamine (CA) as pore-enlarging agent into sodium aluminate solution containing 60-180 g/l of aluminum trioxide to dissolve and filter, and gelatinizing with acidified aluminum salt solution containing 20-40 g/l of aluminum trioxide;gelatinizing at 50-90 deg.C and pH 6.5-8.5, separating solid and liquid, filtering, washing, drying, calcining at 320-350 deg.C for 4-10 hr, and pulverizing to obtain pseudoboehmite with specific surface area up to 331m 2 (iv) g. For example, CN200610019438.X is a preparation method of pseudo-boehmite with large pore volume and high specific surface area, which uses SB powder as seed crystal, adds the seed crystal into sodium aluminate solution to make hydrothermal decomposition, and then makes the above-mentioned material undergo the processes of cooling, vacuum filtration, washing to neutrality, washing with ethyl alcohol and calcining to obtain the pseudo-boehmite with specific surface area of 176.8-213.6 m 2 (iv) g. Although the method improves the specific surface area of the pseudo-boehmite to a certain extent, the method still has the problems of long preparation time, influence on the aperture forming and the structural stability of the product due to the gas released by the stripper plate and the like.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for improving the loading capacity of a pseudo-boehmite loaded catalyst, which can effectively improve the specific surface area and the morphological structure stability of the pseudo-boehmite, further improve the specific surface area and the morphological structure stability of the pseudo-boehmite directly used as a catalyst carrier or a precursor of an alumina catalyst carrier, and finally achieve the aim of improving the loading capacity.
In order to achieve the above object, the present invention provides a method for increasing the loading of a pseudo-boehmite supported catalyst, comprising the steps of:
s1, adding an aluminum salt and a first additive into a mixed solvent to obtain a mixed solution A;
s2.50 ℃, dropwise adding an oxalic acid solution into the mixed solution A obtained in the S1 for three times under magnetic stirring to obtain sol;
s3, dissolving aluminum hydroxide in water, adding a second additive, and continuously stirring to obtain a mixed solution B;
s4, drying the sol supercritical fluid obtained in the step S2 into powder, adding the powder into the mixed solution B obtained in the step S3, uniformly stirring, and placing the solution into a reaction kettle for hydrothermal reaction to obtain a reaction product;
s5, centrifuging, washing and calcining the reaction product obtained in the step S4 to obtain the pseudo-boehmite.
By adopting the technical scheme, S1-2 is used for preparing modified crystal seeds by a sol method, S3 is used for preparing a growth solution, S4 is used for drying and shaping the crystal seeds by supercritical fluid, then the shaped crystal seeds are added into the growth solution to obtain a grown decomposition product through hydrothermal reaction, and S5 is used for calcining and crystal transformation to obtain the pseudoboehmite with high specific surface area and stable morphology structure. Specifically, in S1, the seed crystal is prepared by a sol method, in which the raw material is first dispersed in a solvent, and then subjected to hydrolysis reaction to generate an active monomer, and the active monomer is polymerized to form a sol. Since the raw materials used in the sol method are first dispersed in a solvent to form a solution with low viscosity, uniformity at the molecular level can be obtained in a short time, so that the seed crystal size obtained by the sol method is relatively uniform, and the subsequent uniform control of the particle size of the pseudoboehmite seed crystal is facilitated. In the step, a first additive is directly added to exert a steric hindrance effect, so that the binding force among the pseudo-boehmite crystal seeds is weakened and interstitial pores are enlarged in the sol, thereby generating macropores. In addition, the modified hydrotalcite is added when the solution is prepared, and other elements can be easily uniformly and quantitatively doped through the step of solution reaction, so that uniform doping on the molecular level is realized, and finally the modification of the specific surface area and the structural stability of the pseudo-boehmite by the modified substance is realized. In S2, the pH value of the solution is changed by adding oxalic acid solution in three times, and the interstitial pores of the seed particles are increased by utilizing the pH change in the process, so that the increase of the seed particles and the pore volume is promoted. In S4, before hydrothermal reaction, supercritical fluid drying and shaping are carried out on the sol seed crystal, so that the seed crystal is dried when the drying medium is in a critical temperature and critical pressure state, the seed crystal cannot shrink or crack, the original structure and state can be kept to a great extent, and agglomeration is effectively prevented. Specifically, the drying medium enters the interior of the seed crystal under the supercritical state to exchange with solvent molecules gently and quickly, so that the solvent is replaced, then the fluid is changed into gas from the supercritical state and released from the dried seed crystal, the effect of drying the seed crystal is achieved, and the seed crystal structure is ensured not to shrink and deform. And then adding the crystal seed which is shaped and not agglomerated into the growth solution, directly precipitating crystal nuclei of aluminum hydroxide in the growth solution to the surface of the shaped crystal seed for growth, and modifying the crystal nuclei by using a second additive to finally cause that the crystal nuclei of the pseudo-boehmite are easier to generate, and the generated crystal grains are larger and uniform in grain size. In S5, the crystallinity and the integrity of the pseudoboehmite are improved through sintering, the additive is subjected to crystal form conversion, and finally the modified pseudoboehmite with large specific surface area and stable structure is formed.
Further, in step S1, the aluminum salt is one of aluminum isopropoxide, aluminum hydroxide, or aluminum chloride.
Further, in step S1, the concentration of the aluminum salt is 0.5 to 2mol/L.
Further, in step S1, the first additive is butyl titanate and diethanolamine that can react to generate titanium dioxide, and the concentration of the titanium dioxide is 0.1-0.5mol/L.
Further, in step S1, the molar ratio of the aluminum salt to the first additive is 10: (0.1-1).
Further, in the step S1, the mixed solvent is absolute ethyl alcohol and deionized water in a volume ratio of (6-10): 1. The preferred volume ratio is 8:1.
further, in step S2, the pH of the sol is finally adjusted to 6.5 to 7.5 by the oxalic acid solution.
By adopting the technical scheme, the TiO is prepared by taking the butyl titanate as a titanium source and the diethanolamine as a hydrolysis inhibitor 2 The precursor is prepared for carrying out first modification on the pseudo-boehmite, and a large amount of absolute ethyl alcohol in the solvent can promote the decomposition of the raw materials and the dispersion of the raw materials, so that the crystal grains are more complete and the crystallinity is higher. When oxalic acid is combined with a transition metal titanium element, a soluble complex is formed due to the coordination of oxalic acid, the solubility of the complex is greatly increased, and finally the particle size of the prepared pseudo-boehmite seed crystal is large, the supported titanium amount is high, the surface wet water is less, and the specific surface is not easy to be reduced due to hard agglomeration, so that the particle size of the obtained modified seed crystal is large, and the specific surface area is large.
Further, in step S3, the supercritical fluid drying is high-temperature supercritical organic solvent drying or low-temperature supercritical CO 2 And (5) drying. Preferably low temperatureSupercritical CO 2 And (5) drying. Although the drying process of the supercritical fluid is milder, the damage to the object structure caused by the stress when the object to be dried is dried can be avoided to a greater extent. But low temperature supercritical CO 2 Compared with the high-temperature supercritical organic solvent, the drying temperature is lower, is close to the room temperature, is non-toxic, is not flammable and explosive, is milder compared with the toxic and safety problems of the organic solvent, and is easier to protect the drying modified crystal seed structure.
Further, in the step S3, the concentration of the aluminum hydroxide in the mixed solution B is 0.2-0.4mol/L.
Further, in step S3, the second additive is thiourea or urea.
In step S3, the molar ratio of the second additive to the aluminum hydroxide is (5-10): 1.
By adopting the technical scheme, the second additive is added in an excessive amount, so that a part of the second additive is used as a precipitator, and the excessive part of the second additive is used as a precursor of the carbon-nitrogen modified substance. Specifically, the carbon-nitrogen-modified product may be finally a structure-stable skeleton-like graphene having a large specific surface area due to the skeleton-like multilayer structure.
Further, in step S4, the temperature of the hydrothermal reaction is 120-180 ℃ and the time is 3h.
Further, in step S5, the calcination is performed by rapidly heating to 500 ℃, then briefly maintaining the temperature, and then slowly cooling to 300 ℃ and then maintaining the temperature for a long time.
By adopting the technical scheme, substances such as water and the like are quickly dehydrated through quick temperature rise, a fine and uniform pore structure is formed outside the inner part, the crystal grain growth is favorably reduced by temporarily preserving the temperature, the stable morphological structure is kept, the temperature is raised to 500 ℃, and the TiO is promoted under the condition of ensuring that the pseudo-boehmite does not generate crystal form transformation 2 Respectively adding the precursor and the precursor of the carbon-nitrogen modified substance into TiO 2 And graphene-like conversion to ultimately form TiO 2 Pseudo-boehmite modified simultaneously with graphene and pseudo-boehmite in TiO 2 And the graphene-like material has a larger specific surface area under the simultaneous modification. Finally, the slow cooling and the long-term heat preservation are carried out to eliminateThe inside fine dehydration hole structure of the pseudo-boehmite is removed, the density is improved, and the structural stability is further improved.
Further, in the step S5, the rapid heating rate is 8-12 ℃/min, the short heat preservation time is 10-15min, the slow cooling rate is 1-2 ℃/min, and the long heat preservation time is 1-2h.
Compared with the prior art, the invention has the following beneficial effects:
the invention prepares modified crystal seeds with large particle size and large specific surface area by doping in sol by a sol method and a pH swing method, then dries and shapes the modified crystal seeds by supercritical fluid, then directly nucleates the shaped crystal seeds in a growth solution by a hydrothermal method for growth and is modified again, finally obtains pseudo-boehmite by the calcination processes of rapid heating, short heat preservation, slow cooling and long heat preservation, and the specific surface area of the obtained pseudo-boehmite is not less than 400m 2 (ii)/g, the pore diameter shrinkage at high temperature is within 5%.
Detailed Description
In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.
The invention provides a method for improving the loading capacity of a pseudo-boehmite load catalyst, which comprises the following steps:
s1, adding an aluminum salt and a first additive into a mixed solvent to obtain a mixed solution A;
s2.50 ℃, under magnetic stirring, dropwise adding an oxalic acid solution into the mixed solution A obtained in the S1 for three times to obtain sol;
s3, dissolving aluminum hydroxide in water, adding a second additive, and continuously stirring to obtain a mixed solution B;
s4, drying the sol supercritical fluid obtained in the S2 into powder, adding the powder into the mixed solution B obtained in the S3, uniformly stirring, and placing the mixture into a reaction kettle for hydrothermal reaction to obtain a reaction product;
s5, centrifuging, washing and calcining the reaction product obtained in the step S4 to obtain the pseudo-boehmite.
Specifically, in step S1, the aluminum salt is one of aluminum isopropoxide, aluminum hydroxide, or aluminum chloride.
Specifically, in step S1, the concentration of the aluminum salt is 0.5 to 2mol/L.
Specifically, in step S1, the first additive is butyl titanate and diethanol amine which can react to form titanium dioxide, and the concentration of the titanium dioxide is 0.1-0.5mol/L.
Specifically, in step S1, the molar ratio of the aluminum salt to the first additive is 10: (0.1-1).
Specifically, in step S1, the mixed solvent is absolute ethyl alcohol and deionized water in a volume ratio of (6-10): 1. The preferred volume ratio is 8:1.
specifically, in step S2, the pH of the sol is finally adjusted to 6.5 to 7.5 by the oxalic acid solution.
Specifically, in step S3, the supercritical fluid drying is high-temperature supercritical organic solvent drying or low-temperature supercritical CO drying 2 And (5) drying. Preferably low temperature supercritical CO 2 And (5) drying.
Specifically, in step S3, the concentration of aluminum hydroxide in the mixed solution B is 0.2-0.4mol/L.
Specifically, in step S3, the second additive is thiourea or urea.
Specifically, in step S3, the molar ratio of the second additive to the aluminum hydroxide is (5-10): 1.
Specifically, in step S4, the temperature of the hydrothermal reaction is 120-180 ℃ and the time is 3h.
Specifically, in step S5, the calcination is performed by rapidly heating to 500 ℃, then briefly maintaining the temperature, and then slowly cooling to 300 ℃ and then maintaining the temperature for a long time.
Specifically, in step S5, the rapid heating rate is 8-12 ℃/min, the short heat preservation time is 10-15min, the slow cooling rate is 1-2 ℃/min, and the long heat preservation time is 1-2h.
The following are specific examples:
example 1
A method for improving the loading capacity of a pseudoboehmite supported catalyst comprises the following steps:
s1, adding an aluminum salt and a first additive into a mixed solvent to obtain a mixed solution A;
s2.50 ℃, dropwise adding an oxalic acid solution into the mixed solution A obtained in the S1 for three times under magnetic stirring to obtain sol;
s3, dissolving aluminum hydroxide in water, adding a second additive, and continuously stirring to obtain a mixed solution B;
s4, drying the sol supercritical fluid obtained in the step S2 into powder, adding the powder into the mixed solution B obtained in the step S3, uniformly stirring, and placing the solution into a reaction kettle for hydrothermal reaction to obtain a reaction product;
and S5, centrifuging, washing and calcining the reaction product obtained in the step S4 to obtain the pseudo-boehmite.
In this example, in step S1, the aluminum salt is aluminum isopropoxide.
In this example, the concentration of aluminum salt in step S1 was 0.8mol/L.
In this embodiment, in step S1, the first additive is butyl titanate and diethanolamine which can react to form titanium dioxide, and the concentration of titanium dioxide is 0.15mol/L.
In this embodiment, in step S1, the molar ratio of the aluminum salt to the first additive is 10:0.5.
in this embodiment, in step S1, the mixed solvent is absolute ethanol and deionized water in a volume ratio of 8.
In this embodiment, in step S2, the oxalic acid solution finally adjusts the pH of the sol to 7.
In this embodiment, in step S3, the supercritical fluid is dried to low-temperature supercritical CO 2 And (5) drying.
In this example, in step S3, the concentration of aluminum hydroxide in the mixed solution B was 0.25mol/L.
In this embodiment, in step S3, the second additive is urea.
In this example, in step S3, the molar ratio of the second additive to the aluminum hydroxide is 8.
In this example, in step S4, the hydrothermal reaction was carried out at 180 ℃ for 3 hours.
In this embodiment, in step S5, the calcination is performed by rapidly raising the temperature to 500 ℃, then keeping the temperature for a short time, and then slowly lowering the temperature to 300 ℃ and keeping the temperature for a long time. The speed of rapid temperature rise is 10 ℃/min, the time of short heat preservation is 10min, the speed of slow temperature reduction is 2 ℃/min, and the time of long heat preservation is 2h.
Example 2
A method for improving the loading capacity of a pseudoboehmite supported catalyst comprises the following steps:
s1, adding an aluminum salt and a first additive into a mixed solvent to obtain a mixed solution A;
s2.50 ℃, under magnetic stirring, dropwise adding an oxalic acid solution into the mixed solution A obtained in the S1 for three times to obtain sol;
s3, dissolving aluminum hydroxide in water, adding a second additive, and continuously stirring to obtain a mixed solution B;
s4, drying the sol supercritical fluid obtained in the step S2 into powder, adding the powder into the mixed solution B obtained in the step S3, uniformly stirring, and placing the solution into a reaction kettle for hydrothermal reaction to obtain a reaction product;
s5, centrifuging, washing and calcining the reaction product obtained in the step S4 to obtain the pseudo-boehmite.
In this example, in step S1, the aluminum salt is aluminum hydroxide.
In this example, the concentration of aluminum salt in step S1 was 0.5mol/L.
In this embodiment, in step S1, the first additive is tetrabutyl titanate and diethanol amine capable of reacting to generate titanium dioxide, and the concentration of titanium dioxide is 0.1mol/L.
In this example, the molar ratio of the aluminum salt to the first additive in step S1 is 10:0.1.
in this embodiment, in step S1, the mixed solvent is anhydrous ethanol and deionized water in a volume ratio of 6.
In this example, in step S2, the oxalic acid solution finally adjusts the pH of the sol to 6.5.
In this embodiment, in step S3, the supercritical fluid drying is high-temperature supercritical organic solvent drying.
In this example, in step S3, the concentration of aluminum hydroxide in the mixed solution B was 0.2mol/L.
In this embodiment, in step S3, the second additive is thiourea.
In this embodiment, in step S3, the molar ratio of the second additive to the aluminum hydroxide is 5.
In this example, in step S4, the hydrothermal reaction was carried out at 120 ℃ for 3 hours.
In this embodiment, in step S5, the calcination is performed by rapidly raising the temperature to 500 ℃, then keeping the temperature for a short time, and then slowly lowering the temperature to 300 ℃ and keeping the temperature for a long time. The speed of rapid temperature rise is 8 ℃/min, the time of short heat preservation is 12min, the speed of slow temperature reduction is 1.5 ℃/min, and the time of long heat preservation is 1.5h.
Example 3
A method for improving the loading capacity of a pseudoboehmite supported catalyst comprises the following steps:
s1, adding an aluminum salt and a first additive into a mixed solvent to obtain a mixed solution A;
s2.50 ℃, dropwise adding an oxalic acid solution into the mixed solution A obtained in the S1 for three times under magnetic stirring to obtain sol;
s3, dissolving aluminum hydroxide in water, adding a second additive, and continuously stirring to obtain a mixed solution B;
s4, drying the sol supercritical fluid obtained in the step S2 into powder, adding the powder into the mixed solution B obtained in the step S3, uniformly stirring, and placing the solution into a reaction kettle for hydrothermal reaction to obtain a reaction product;
and S5, centrifuging, washing and calcining the reaction product obtained in the step S4 to obtain the pseudo-boehmite.
In this embodiment, in step S1, the aluminum salt is aluminum chloride.
In this example, the concentration of aluminum salt in step S1 was 2mol/L.
In this embodiment, in step S1, the first additive is tetrabutyl titanate and diethanol amine capable of reacting to generate titanium dioxide, and the concentration of titanium dioxide is 0.5mol/L.
In this embodiment, in step S1, the molar ratio of the aluminum salt to the first additive is 10:1.
in this embodiment, in step S1, the mixed solvent is anhydrous ethanol and deionized water in a volume ratio of 10.
In this example, in step S2, the oxalic acid solution finally adjusts the pH of the sol to 7.5.
In this embodiment, in step S3, the supercritical fluid is dried to low-temperature supercritical CO 2 And (5) drying.
In this example, in step S3, the concentration of aluminum hydroxide in the mixed solution B was 0.4mol/L.
In this embodiment, in step S3, the second additive is urea.
In this embodiment, in step S3, the molar ratio of the second additive to the aluminum hydroxide is 10.
In this example, in step S4, the hydrothermal reaction was carried out at 180 ℃ for 3 hours.
In this embodiment, in step S5, the calcination is performed by rapidly raising the temperature to 500 ℃, then keeping the temperature for a short time, and then slowly lowering the temperature to 300 ℃ and keeping the temperature for a long time. The rapid heating rate is 12 ℃/min, the short heat preservation time is 15min, the slow cooling rate is 1 ℃/min, and the long heat preservation time is 1h.
Comparative example 1
In this comparative example, the first additive in step S1 was directly titanium dioxide powder. Except for this, the other experimental procedures were exactly the same as those of example 1.
Comparative example 2
In this comparative example, no first additive was added in step S1. Except for this, the other experimental procedures were exactly the same as those of example 1.
Comparative example 3
In this comparative example, oxalic acid added in step S2 was added at once. Otherwise, the other experimental procedures were exactly the same as those of example 1.
Comparative example 4
In this comparative example, the second additive added in step S3 was not excessive. Otherwise, the other experimental procedures were exactly the same as those of example 1.
Comparative example 5
In this comparative example, ordinary vacuum drying was employed in step S4. Otherwise, the other experimental procedures were exactly the same as those of example 1.
Comparative example 6
In the present comparative example, the calcination process in step S5 was carried out by raising the temperature to 500 ℃ at 2 ℃/min and then maintaining the temperature for 2 hours. Otherwise, the other experimental procedures were exactly the same as those of example 1.
Testing and analysis
The specific surface areas of the pseudo-boehmite obtained in examples 1-3 and comparative examples 1-6 were measured by low temperature liquid nitrogen adsorption, and then the pseudo-boehmite obtained in examples 1-3 and comparative examples 1-6 were subjected to high temperature calcination heat treatment at 800 deg.C, 10 hours and 900 deg.C for 10 hours, respectively, and the specific surface area of the pseudo-boehmite after the high temperature calcination heat treatment was measured again by low temperature liquid nitrogen adsorption, and the pore diameter shrinkage after calcination at 800 deg.C and 900 deg.C was calculated from the change in specific surface area, respectively, and the test results are shown in Table 1.
TABLE 1 test results of examples 1-3 and comparative examples 1-6
Figure BDA0003765032250000101
Figure BDA0003765032250000111
As can be seen from Table 1, the pseudoboehmite obtained in examples 1 to 3 had a specific surface area of not less than 400m 2 The shrinkage of pore diameter under high temperature is within 5 percent, and the structure stability is good. As can be seen from the comparison between examples 1-3 and comparative examples 1 and 2, the titanium dioxide modification by directly adding titanium dioxide in comparative example 1, the graphene-like modification by only using the second additive without using the first additive in comparative example 2 has a limited increase in the specific surface area of the pseudo-boehmite, which also indicates that the titanium dioxide raw material is prepared by sol method in examples 1-3The oxalic acid is added during solution preparation, the oxalic acid is easily uniformly and quantitatively doped through a solution reaction step, uniform doping preparation on a molecular level is realized, and a soluble complex is formed due to the coordination effect of the oxalic acid when the oxalic acid is combined with a transition metal titanium element after the oxalic acid is dropwise added, so that the solubility of the complex is increased, and the beneficial effect of increasing the specific surface area of the pseudo-boehmite is finally realized. Compared with the comparative example 3, the oxalic acid dropping times also influence the specific surface area of the pseudo-boehmite, the more the dropping times are, the more the pH change is easily caused, the solubility of the complex after the oxalic acid is combined with the transition metal titanium element is increased more and more, the mesopores of the seed particles are increased more and more, and the increase of the seed particles and the pore volume is promoted. It can be seen from comparison with comparative example 4 that comparative example 4, in which the titanium dioxide-modified pseudoboehmite is virgin with the first additive alone and without the second additive, also has a limited increase in the specific surface area of the pseudoboehmite. In combination with comparative example 1, it was found that either titania-modified pseudoboehmite or virgin titania-modified pseudoboehmite had a limited effect on the specific surface area of the single titania-modified pseudoboehmite. Compared with the single graphene-like modified pseudo-boehmite of comparative example 2, the effect of increasing the specific surface area by single titanium dioxide modification is not as good as that by single graphene-like modification, but the high-temperature pore diameter shrinkage rate of the pseudo-boehmite modified by single graphene-like is not as good as that of the pseudo-boehmite modified by single titanium dioxide, which shows that the pseudo-boehmite modified by single titanium dioxide has better structural stability. Compared with comparative examples 5 and 6, the comparative example 5 adopts common drying, and the comparative example 6 adopts slow-heating long-time heat-preservation calcination, so that the obtained pseudoboehmite has larger specific surface area increased by two modifications, but the pore diameter shrinkage rate at high temperature is very large, which shows that the drying and calcination modes have important influence on the structural stability of the pseudoboehmite with large specific surface area.
While there have been shown and described what are at present considered the fundamental principles and essential features of the invention and its advantages, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (10)

1. A method for improving the loading capacity of a pseudo-boehmite supported catalyst is characterized by comprising the following steps:
s1, adding an aluminum salt and a first additive into a mixed solvent to obtain a mixed solution A;
s2.50 ℃, dropwise adding an oxalic acid solution into the mixed solution A obtained in the S1 for three times under magnetic stirring to obtain sol;
s3, dissolving aluminum hydroxide in water, adding a second additive, and continuously stirring to obtain a mixed solution B;
s4, drying the sol supercritical fluid obtained in the step S2 into powder, adding the powder into the mixed solution B obtained in the step S3, uniformly stirring, and placing the solution into a reaction kettle for hydrothermal reaction to obtain a reaction product;
s5, centrifuging, washing and calcining the reaction product obtained in the step S4 to obtain the pseudo-boehmite.
2. The method for increasing the loading capacity of the pseudo-boehmite supported catalyst according to claim 1, wherein in step S1, the first additive is tetrabutyl titanate and diethanolamine which can react to form titanium dioxide, and the concentration of the titanium dioxide is 0.1-0.5mol/L.
3. The method for increasing the loading of the pseudoboehmite supported catalyst according to claim 1, characterized in that in step S1, the molar ratio of the aluminum salt to the first additive is 10: (0.1-1).
4. The method for increasing the loading capacity of the pseudoboehmite supported catalyst according to claim 1, wherein in the step S1, the mixed solvent is absolute ethyl alcohol and deionized water in a volume ratio of (6-10): 1.
5. The method for increasing the loading of the pseudo-boehmite supported catalyst according to claim 1, wherein in the step S2, the pH value of the sol is finally adjusted to 6.5-7.5 by the oxalic acid solution.
6. The method for increasing the loading capacity of the pseudoboehmite supported catalyst according to claim 1, wherein in step S3, the supercritical fluid drying is high-temperature supercritical organic solvent drying or low-temperature supercritical CO drying 2 And (5) drying.
7. The method for increasing the loading of the pseudoboehmite supported catalyst according to claim 1, characterized in that in step S3, the second additive is thiourea or urea, and the molar ratio of the second additive to the aluminum hydroxide is (5-10): 1.
8. The method for increasing the loading capacity of the pseudo-boehmite supported catalyst according to claim 1, wherein the temperature of the hydrothermal reaction is 120-180 ℃ and the time is 3h in step S4.
9. The method for increasing the loading capacity of the pseudo-boehmite supported catalyst according to claim 1, wherein in the step S5, the calcination is performed by quickly raising the temperature to 500 ℃ and then keeping the temperature for a short time, and then slowly lowering the temperature to 300 ℃ and then keeping the temperature for a long time.
10. The method for increasing the loading capacity of the pseudo-boehmite supported catalyst according to claim 9, wherein in the step S5, the rapid temperature rise rate is 8-12 ℃/min, the short heat preservation time is 10-15min, the slow temperature decrease rate is 1-2 ℃/min, and the long heat preservation time is 1-2h.
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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2249022A1 (en) * 1972-10-06 1974-04-18 Laporte Industries Ltd Pseudoboehmite alumina prodn - by controlled reaction of aluminium sulphate and sodium aluminate solns
JPH10109030A (en) * 1996-10-04 1998-04-28 Japan Energy Corp Pseudo-boehmite for catalyst carrier and its production
GB0428557D0 (en) * 2004-12-30 2005-02-09 Magnesium Elektron Ltd Thermally stable doped and undoped porous aluminium oxides and nanocomposite CeO -ZrO and A1 O containing mixed oxides
CN101367535A (en) * 2008-10-09 2009-02-18 武汉理工大学 Hydrothermal method for preparing gamma-AL2O3 hollow microsphere polishing material without mould plate
CN103466669A (en) * 2013-09-27 2013-12-25 中国海洋石油总公司 Method of using aluminium hydroxide to make pseudo-boehmite in hydrothermal synthesis mode
CN104043454A (en) * 2014-06-10 2014-09-17 中国华能集团清洁能源技术研究院有限公司 Novel nano composite methanation catalyst and preparation method thereof
CN105417562A (en) * 2015-12-28 2016-03-23 深圳市星源材质科技股份有限公司 Synthesis method of alpha-alumina by hydrothermal method

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2249022A1 (en) * 1972-10-06 1974-04-18 Laporte Industries Ltd Pseudoboehmite alumina prodn - by controlled reaction of aluminium sulphate and sodium aluminate solns
JPH10109030A (en) * 1996-10-04 1998-04-28 Japan Energy Corp Pseudo-boehmite for catalyst carrier and its production
GB0428557D0 (en) * 2004-12-30 2005-02-09 Magnesium Elektron Ltd Thermally stable doped and undoped porous aluminium oxides and nanocomposite CeO -ZrO and A1 O containing mixed oxides
CN101367535A (en) * 2008-10-09 2009-02-18 武汉理工大学 Hydrothermal method for preparing gamma-AL2O3 hollow microsphere polishing material without mould plate
CN103466669A (en) * 2013-09-27 2013-12-25 中国海洋石油总公司 Method of using aluminium hydroxide to make pseudo-boehmite in hydrothermal synthesis mode
CN104043454A (en) * 2014-06-10 2014-09-17 中国华能集团清洁能源技术研究院有限公司 Novel nano composite methanation catalyst and preparation method thereof
CN105417562A (en) * 2015-12-28 2016-03-23 深圳市星源材质科技股份有限公司 Synthesis method of alpha-alumina by hydrothermal method

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
苗壮;史建公;郝建薇;范群波;张敏宏;: "α-Al_2O_3载体的制备及其在环氧乙烷银催化剂中的应用", 中外能源, no. 02 *
蔡卫权;余小锋;: "高比表面大中孔拟薄水铝石和γ-Al_2O_3的制备研究", 化学进展, no. 09 *
马成成;姚楠;李小年;: "大孔径和高比表面积γ-Al_2O_3材料的合成", 工业催化, no. 10 *

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