A method for preparing filamentous pseudoboehmite by static settling and aging, and filamentous pseudoboehmite
By using static sedimentation and aging treatment, and by mixing carbonized liquid with hot water and separating it by static sedimentation, the directional growth of nanoparticles was achieved, which solved the problem of uneven crystal phase purity and morphology distribution in traditional methods, and prepared high-purity and high-stability filamentous pseudoboehmite.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHALCO SHANDONG NEW MATERIALS CO LTD
- Filing Date
- 2025-07-30
- Publication Date
- 2026-07-14
AI Technical Summary
Traditional methods for preparing boehmite are difficult to control precisely in terms of crystal phase purity and morphology distribution, resulting in poor product quality stability. In particular, impurity phases and non-uniform morphologies are easily generated in the hydrothermal synthesis method.
By using static sedimentation and aging treatment, the directional growth of nanoparticles is achieved by mixing carbonized liquid with water at a preset temperature. Combined with static sedimentation and solid-liquid separation, micron-sized particles are separated. Subsequently, aging treatment is carried out in a pure environment to promote the directional growth of nanoparticles and form filamentous pseudoboehmite.
This method achieves high aspect ratio and morphological uniformity of filamentous pseudoboehmite, improves crystal phase purity and product stability, reduces the impurity content of gibbsite, and enhances product quality consistency.
Smart Images
Figure CN120817619B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of alumina material preparation technology, and in particular to a method for preparing filamentous pseudoboehmite by static sedimentation and aging, and the filamentous pseudoboehmite. Background Technology
[0002] Boehmite, as a crucial alumina precursor, exhibits broad application potential in numerous fields such as catalyst supports, adsorbents, and ceramic materials due to its unique physicochemical properties. Boehmite exhibits diverse morphologies, including spherical, filamentous, spindle-shaped, and filamentous forms, each displaying different performance characteristics in applications. Among these, filamentous boehmite demonstrates significant advantages in certain high-end applications due to its unique aspect ratio and high specific surface area; however, the preparation of filamentous boehmite is the most challenging among all morphologies.
[0003] Traditional methods for preparing boehmite involve complex multi-step reaction processes. For example, the aluminum salt precipitation method requires precise control of solution pH, reaction temperature, and the rate of precipitant addition, making the operation cumbersome. Although hydrothermal synthesis can currently control the crystal phase of boehmite and save reaction time, the purity of the crystal phase obtained by hydrothermal synthesis is not high, and other impurities are often mixed in the boehmite product. This makes the particle morphology of the boehmite product easily affected by fluctuations in reaction conditions, making precise control difficult. These factors result in poor quality stability of the boehmite product. Summary of the Invention
[0004] This application provides a method for preparing filamentous pseudoboehmite through static sedimentation and aging, and the filamentous pseudoboehmite itself, to solve the following technical problem: how to simultaneously improve the crystal phase purity and morphology distribution of pseudoboehmite products.
[0005] In a first aspect, embodiments of this application provide a method for preparing filamentous pseudoboehmite through static sedimentation and aging, the method comprising:
[0006] Carbon dioxide and sodium aluminate solution are subjected to a carbonization reaction to obtain a carbonized liquid containing nanoparticles and micron-sized particles;
[0007] Water at a preset temperature and carbonization liquid containing nanoparticles and micron particles are mixed at a preset volume ratio to initially induce the nanoparticles to grow in a directional manner to form a filamentous structure, thereby obtaining a mixed slurry containing nanoparticles, filamentous structures and micron particles; wherein, the temperature of the water is higher than the temperature of the carbonization liquid;
[0008] The slurry containing nanoparticles, filamentous structures and micron particles is subjected to static sedimentation and solid-liquid separation in sequence to separate the micron particles and obtain the supernatant.
[0009] The upper clear liquid is aged to allow the nanoparticles and filamentous structures to grow in a directional manner to form filamentous pseudoboehmite, thus obtaining an aged slurry.
[0010] The aged slurry was post-treated to obtain filamentous pseudoboehmite.
[0011] Optionally, the preset volume ratio is 1:(0.5 to 2.5); and / or
[0012] The preset temperature is 70°C to 100°C.
[0013] Optionally, the temperature of the mixed slurry is between 55°C and 95°C.
[0014] Optionally, the aging treatment temperature is 70°C to 80°C, and the aging treatment time is 4 hours to 6 hours.
[0015] Optionally, the settling time is 15 min to 60 min.
[0016] Optionally, the settling time is 20 to 60 minutes.
[0017] Optionally, the mass concentration of alumina in the carbonization solution is from 0.5 g / L to 6 g / L.
[0018] Optionally, the step of post-processing the aged slurry to obtain filamentous pseudoboehmite includes the following steps:
[0019] The aging slurry is subjected to solid-liquid separation to obtain a solid-phase aging material;
[0020] The solid-phase aging material is washed to obtain a washing material;
[0021] The washing material is dried to obtain filamentous pseudoboehmite.
[0022] Secondly, embodiments of this application provide a filamentous pseudoboehmite, which is prepared by the method described in the first aspect. The crystallinity of the filamentous pseudoboehmite is 50% to 60%, and the grain size of the filamentous pseudoboehmite is [missing information]. to The mass of the gibbsite in the filamentous pseudoboehmite is 0.5% to 1.0% of the mass of the filamentous pseudoboehmite.
[0023] Optionally, the length of the filamentous boehmite whiskers is 5 μm to 15 μm, the diameter of the filamentous boehmite whiskers is 0.2 μm to 2.0 μm, and the aspect ratio of the filamentous boehmite whiskers is 5 to 20.
[0024] The technical solutions provided in this application have the following advantages compared with the prior art:
[0025] This application provides a method for preparing filamentous pseudoboehmite through static sedimentation and aging. This technique precisely controls the volume ratio of water to carbonization liquid at a preset temperature to achieve water dispersion and heat the carbonization liquid, thereby creating an induction environment with excellent dispersibility and suitable temperature. This environment helps to initially guide the growth of nanoparticles along a specific direction, forming a filamentous structure. Subsequently, through static sedimentation, the Brownian motion of the filamentous structure and nanoparticles, as well as the aggregation and static sedimentation effect between micron-sized particles, are utilized to achieve effective separation of micron-sized particles from the filamentous structure and nanoparticles. Finally, the supernatant obtained after separation is aged by adjusting the temperature and pH to promote the stable growth of the filamentous structure and nanoparticles into a one-dimensional chain structure, ultimately yielding a filamentous pseudoboehmite product with a highly uniform morphological distribution. Attached Figure Description
[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.
[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0028] Figure 1 A schematic flowchart of a method for preparing filamentous pseudoboehmite through static sedimentation and aging is provided in an embodiment of this application.
[0029] Figure 2 A detailed flowchart illustrating a method for preparing filamentous pseudoboehmite through static sedimentation and aging, as provided in this application embodiment;
[0030] Figure 3 A scanning electron microscope (SEM) image of the filamentous boehmite product prepared by a method for preparing filamentous boehmite through static sedimentation and aging as provided in Embodiment 1 of this application.
[0031] Figure 4A scanning electron microscope (SEM) schematic diagram of the filamentous boehmite product prepared by a method for preparing filamentous boehmite through static sedimentation and aging, as provided in Comparative Example 1 of this application. Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0033] The range descriptions used in this application, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values within that range. For example, the range descriptions of "1 to 6" or "1 to 6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "comprising" and others used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships involved in this document, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained by purchasing from the market or by existing methods.
[0034] It should be noted that, regarding the prior art described in the background section, the inventors have discovered the following problems:
[0035] (1) Challenges in controlling directional topography:
[0036] Traditional hydrothermal synthesis methods struggle to precisely induce the growth of nanoparticles into high aspect ratio filamentous structures, easily leading to impurities or heterogeneous morphologies. Therefore, the synergistic reaction temperature of the carbonization liquid and hot water used in traditional hydrothermal synthesis methods needs to be controlled, and their mixing ratio optimized to create a suitable slurry environment. This promotes the preferential growth of nanoparticles along specific crystal planes, achieving precise control over the aspect ratio of the filamentous pseudo-boehmite morphology. Simultaneously, morphological damage caused by the dissolution and recrystallization of nanoparticles must be avoided.
[0037] (2) Impurity phase suppression bottleneck:
[0038] During the hydrothermal synthesis process, gibbsite Al(OH)3 is readily generated, which severely affects the crystalline phase purity of the pseudoboehmite product. Furthermore, high-purity filamentous pseudoboehmite requires the gibbsite content to be controlled at ≤1.0%. Therefore, optimizing the aging process is crucial to improve the phase transition pathway of nanoparticles and effectively suppress the formation of gibbsite.
[0039] (3) The contradiction between process efficiency and stability:
[0040] Traditional hydrothermal synthesis methods rely on multi-step reaction control, such as pH adjustment and precipitant addition, making the overall operation cumbersome and complex. Therefore, there is an urgent need to explore an innovative approach to achieve efficient separation of nanoparticles and micron-sized particles through static sedimentation of carbonized liquid, and to prepare filamentous pseudoboehmite by combining it with an aging process; at the same time, these micron-sized particles are prone to forming gibbsite, which affects the crystal phase purity of pseudoboehmite.
[0041] In view of the above-mentioned deficiencies of the prior art, this application provides a method for preparing filamentous pseudoboehmite through static sedimentation and aging. This method achieves the following objectives by precisely controlling the alumina concentration of the carbide solution, the mixing temperature, the static sedimentation time, and the aging conditions:
[0042] 1. Breakthrough in controlling filamentous morphology: By synergistically regulating the temperature between the carbonization liquid and water at a preset temperature, the nanoparticles in the carbonization liquid are induced to grow into filamentous structures with a high aspect ratio, overcoming the defect of uneven particle morphology in traditional methods.
[0043] 2. Improve the purity and performance of the product crystal phase: Optimize the temperature (≥65℃) and aging conditions (70℃ to 80℃) of the mixed slurry, inhibit the formation of gibbsite (content ≤1.0%), and improve the crystallinity (50% to 60%) and grain size of pseudoboehmite. to To ensure uniformity of filament morphology (length from 5 μm to 15 μm and diameter from 0.2 μm to 2 μm).
[0044] Figure 1 An exemplary schematic diagram of a method for preparing filamentous pseudoboehmite through static sedimentation and aging according to an embodiment of this application is shown.
[0045] like Figure 1 As shown in the embodiments of this application, a method for preparing filamentous pseudoboehmite through static sedimentation and aging is provided, the method comprising:
[0046] S1. Carbon dioxide and sodium aluminate solution are subjected to a carbonization reaction to obtain a carbonized liquid containing nanoparticles and micron particles;
[0047] S2. At a preset volume ratio, water at a preset temperature and the carbonization liquid containing nanoparticles and micron particles are mixed to initially induce the nanoparticles to grow in a directional manner to form a filamentous structure, thereby obtaining a mixed slurry containing nanoparticles, filamentous structures and micron particles; wherein, the temperature of the water is higher than the temperature of the carbonization liquid;
[0048] S3. The slurry containing nanoparticles, filamentous structures and micron particles is subjected to static sedimentation and solid-liquid separation in sequence to separate the micron particles and obtain the supernatant.
[0049] S4. The upper clear liquid is subjected to aging treatment, so that the nanoparticles and the filamentous structure grow in a directional manner to form filamentous pseudoboehmite, and an aged slurry is obtained.
[0050] S5. The aged slurry is post-treated to obtain filamentous pseudoboehmite.
[0051] It should be noted that this application provides a method for preparing filamentous pseudoboehmite through static sedimentation and aging. This method utilizes the differences in the physicochemical properties of the carbonization liquid components and achieves the enrichment and directional growth of target nanoparticles through stepwise processing (hot water temperature control treatment + static sedimentation separation + aging), while excluding micron-sized particles. The specific mechanism of this method is as follows:
[0052] 1. The two-component nature of the carbonization reaction products:
[0053] When carbon dioxide reacts with sodium aluminate solution, an amorphous aluminum hydroxide precipitate (i.e., boehmite precursor) is formed. This reaction process typically produces a polydisperse particulate system, including:
[0054] 1) Nanoparticles: They are very small in size (usually a few nanometers to tens of nanometers), have high surface energy, are in a metastable or metastable state, are sensitive to aging conditions, and are the target precursors for forming the final filamentous product.
[0055] 2) Micron-sized particles: These are relatively large (usually in the micrometer range) and more stable. They are aggregates or impurity phases that form rapidly during the reaction (may contain impurities such as silicon and iron, or irregular large particles formed by premature and disordered agglomeration of nanoparticles). These micron-sized particles usually do not have the ability to form ideal filamentous morphologies, and they are also prone to crystallization into gibbsite.
[0056] 2. Hot water mixing and settling separation (key impurity removal and enrichment steps):
[0057] Preset volume ratio warm water mixing: Using hot water at a temperature higher than that of the carbonized liquid for mixing, its core function is to reduce the viscosity of the system and introduce gentle thermal convection.
[0058] 1) Reduce viscosity: This facilitates the movement and settling of micron-sized particles (according to Stokes' Law, the settling rate is inversely proportional to viscosity).
[0059] 2) Mild thermal convection: promotes collisions between particles, but not so violently as to damage the structure or cause excessive turbulence.
[0060] 3. Sedimentation mechanism (separation of nanoparticles and micron-sized particles):
[0061] (1) Gravity difference dominates: Micron particles have large size and relatively high density, which makes them easy to form dense flocs and settle quickly under the action of gravity.
[0062] 1) Brownian motion maintains suspension: The nanoparticles are extremely small in size and are subjected to strong Brownian motion. Their thermal energy is sufficient to resist gravity and allow them to remain stably suspended in the upper liquid phase for a long time.
[0063] 2) Synergistic effect of temperature: The temperature environment maintained by hot water helps to maintain the colloidal stability of nanoparticles (preventing premature flocculation) and at the same time accelerates the static sedimentation kinetics of large particles.
[0064] (2) Results of solid-liquid separation:
[0065] 1) Supernatant: This mainly contains highly enriched nanoparticles with good particle size uniformity, as well as dissolved sodium aluminate and carbonates. Micron-sized particles are effectively allowed to settle to the bottom and are removed along with the sediment. This step significantly improves the crystalline phase purity of the materials subsequently processed.
[0066] 2) Bottom layer slurry: contains micron-sized particles that have settled after standing.
[0067] 4. Aging treatment (key to directional growth of filamentous morphology):
[0068] (1) Enriched and purified nanoparticle environment: The supernatant contains almost only the target nanoparticles, eliminating interference from micron-sized particles. These nanoparticles have:
[0069] 1) High surface energy: drives the ripening process.
[0070] Small and relatively uniform size: provides a good starting point for subsequent directional growth.
[0071] (2) Directional growth mechanism in the aging process:
[0072] 1) Aging: Under aging temperature and time, the system tends to decrease its total surface energy. Smaller nanoparticles with higher solubility gradually dissolve, releasing aluminum species Al(OH)4. - They migrate and deposit on the surface of larger or more stable colloidal particles.
[0073] 2) Directional adhesion: The dissolution-redeposition process tends to occur along specific crystal planes. Under suitable aging conditions (temperature, pH, ionic strength, and absence of impurities), nanoparticles tend to grow and connect through directional adhesion. That is, they approach each other and align and combine according to a specific crystallographic orientation to form a one-dimensional chain structure.
[0074] 3) Suppressing isotropic growth: Temperature-controlled aging in a weakly alkaline environment (usually temperature controlled in a weakly alkaline environment) is conducive to the stability and growth of specific crystal faces, suppressing the growth rate of other directions, thereby promoting the development of one-dimensional filamentous or fibrous morphology.
[0075] 4) A uniform environment promotes uniform morphology: Due to the relatively pure composition of the supernatant and the narrow size distribution of the colloidal particles, all nanoparticles are in highly similar growth environments. This greatly promotes the consistency of growth rate and direction, ultimately resulting in a highly uniform filamentous morphology distribution of the product.
[0076] 5. Mechanism for simultaneously improving crystal phase purity and morphology:
[0077] (1) Improved crystal phase purity: The static sedimentation separation step effectively separates and removes micron-sized particles from the target nanoparticles (supernatant). The subsequent aging treatment targets the purified nanoparticle system.
[0078] (2) Improved uniformity of morphological distribution:
[0079] 1) Precursor homogenization: After static sedimentation and separation, the precursors that enter the aging process are nanoparticles with relatively uniform size. This provides a uniform and high-quality "seed" for subsequent directional growth.
[0080] 2) Elimination of interference: Micron particles (which may become heterogeneous nucleation centers or interfere with the directional attachment process) and impurity ions (which may adsorb on specific crystal planes, changing the growth rate or causing defects) are removed, creating a pure chemical environment conducive to uniform and directional growth.
[0081] 3) Optimized growth conditions: Based on pure and uniform precursors, precisely controlled aging conditions (temperature, time, pH) further ensured that the filamentous morphology grew stably and uniformly along the target direction.
[0082] In summary, the present application provides a method for preparing filamentous pseudoboehmite through static sedimentation and aging, which utilizes the following mechanism:
[0083] 1. Carbonization produces a two-component system (nanocolloids + micron particles / impurities).
[0084] 2. Hot water mixing promotes settling: Large / impure micron particles settle rapidly to the bottom and are separated and discarded → a clear supernatant rich in pure nanoparticles is obtained → significantly improving the purity of the crystal phase.
[0085] 3. Pure and uniform nanoparticles undergo directional growth (curing + directional adhesion) under optimized aging conditions to form a uniform filamentous morphology.
[0086] Therefore, the present application provides a method for preparing filamentous pseudoboehmite through static sedimentation and aging. This method first uses hot water to regulate the carbonization liquid to form a good induction environment, and then uses a relatively simple physical static sedimentation step to achieve the enrichment and purification of the target precursor (nanoparticles) and the effective removal of impurities / interfering phases (micron particles). This lays a decisive foundation for the subsequent directional growth of nanoparticles into a uniform filamentous structure in a pure and uniform environment, thereby simultaneously improving the crystal phase purity and morphological distribution uniformity of the product.
[0087] In some optional embodiments, the preset volume ratio is 1:(0.5 to 2.5); and / or
[0088] The preset temperature is 70°C to 100°C.
[0089] In these embodiments, a preset volume ratio of 1:(0.5 to 2.5) allows the water at a preset temperature to raise the temperature of the carbonization solution, introducing gentle thermal convection and simultaneously reducing the viscosity of the carbonization solution system. This provides a certain inducing environment for the carbonization solution, enabling the nanoparticles to grow directionally into filamentous structures. Furthermore, a preset temperature of 70°C to 100°C allows the water to effectively raise the temperature of the carbonization solution and reduce the viscosity of the carbonization solution system, further enabling the nanoparticles to grow directionally into filamentous structures.
[0090] The preset volume can be 1:0.5, 1:1.0, 1:1.5, 1:2.0 or 1:2.5.
[0091] The preset temperature can be 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃.
[0092] In some alternative embodiments, the temperature of the mixed slurry is between 55°C and 95°C.
[0093] In these embodiments, the mixed slurry at a temperature of 55°C to 95°C can maintain the stability of the nanoparticles and filamentous structures, facilitating the subsequent separation of the nanoparticles, filamentous structures and micron-sized particles by static sedimentation, thereby obtaining a pure supernatant.
[0094] The temperature of the mixed slurry can be 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃ or 95℃.
[0095] In some alternative embodiments, the aging treatment is performed at a temperature of 70°C to 80°C for a duration of 4 to 6 hours.
[0096] In these embodiments, aging treatment at a temperature of 70°C to 80°C and for a time of 4 to 6 hours can promote the stable growth of filamentous structures and nanoparticles into one-dimensional chain structures, ultimately producing filamentous pseudoboehmite products with a highly uniform morphological distribution.
[0097] The aging treatment temperature can be 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃ or 80℃.
[0098] The aging process can last for 4 hours, 4.5 hours, 5.0 hours, 5.5 hours, or 6.0 hours.
[0099] In some alternative implementations, the settling time is 15 to 60 minutes.
[0100] In these embodiments, a settling time of 15 to 60 minutes allows sufficient time for the agglomeration of micron particles to form aggregates, thereby achieving physical separation between micron particles, filamentous structures, and nanoparticles, improving the crystal phase purity of boehmite in the supernatant, and facilitating subsequent aging treatment to form filamentous boehmite.
[0101] The settling time can be 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min.
[0102] In some alternative implementations, the settling time is 20 to 60 minutes.
[0103] In these embodiments, a settling period of 20 to 60 minutes can further achieve physical separation between micron-sized particles, filamentous structures and nanoparticles, and improve the crystal phase purity of the supernatant, facilitating subsequent aging treatment to form filamentous pseudoboehmite.
[0104] The settling time can be 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min.
[0105] In some alternative embodiments, the mass concentration of alumina in the carbonization liquid is from 0.5 g / L to 6 g / L.
[0106] In these embodiments, a carbonization solution with an alumina mass concentration of 0.5 g / L to 6 g / L can provide sufficient alumina components, facilitating the formation of adequate nanoparticles during the subsequent mixing stage.
[0107] The mass concentration of alumina in the carbonization solution can be 0.5 g / L, 1.0 g / L, 1.5 g / L, 2.0 g / L, 2.5 g / L, 3.0 g / L, 3.5 g / L, 4.0 g / L, 4.5 g / L, 5.0 g / L, 5.5 g / L, or 6.0 g / L.
[0108] In some optional embodiments, the post-treatment of the aged slurry to obtain filamentous pseudoboehmite includes the following steps:
[0109] S501. The aging slurry is subjected to solid-liquid separation to obtain a solid-phase aging material;
[0110] S502. Wash the solid-phase aging material to obtain a washing material;
[0111] S503. The washing material is dried to obtain filamentous pseudoboehmite.
[0112] In these embodiments, filamentous boehmite formed in the aged slurry can be separated and purified by solid-liquid separation, washing and drying, thereby obtaining filamentous boehmite with excellent crystal phase purity and morphology.
[0113] like Figure 3 As shown in the illustration, this application provides an exemplary embodiment of a filamentous pseudoboehmite.
[0114] Based on an overall concept, such as Figure 3 As shown, this application provides a filamentous pseudoboehmite, which is prepared by the method described in the first aspect. The crystallinity of the filamentous pseudoboehmite is 50% to 60%, and the grain size of the filamentous pseudoboehmite is [missing information]. to The mass of the gibbsite in the filamentous pseudoboehmite is 0.5% to 1.0% of the mass of the filamentous pseudoboehmite.
[0115] The filamentous pseudoboehmite is prepared based on the above method. The specific steps of the method can be referred to the above embodiments. Since the filamentous pseudoboehmite adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.
[0116] It should be noted that the crystallinity is 50% to 60% and the grain size is... to The presence of fibrous pseudoboehmite indicates that the fibrous pseudoboehmite has an excellent crystal phase; furthermore, the presence of 0.5% to 1.0% of the mass of fibrous pseudoboehmite in the fibrous pseudoboehmite indicates that the fibrous pseudoboehmite has a low impurity content and high crystal phase purity.
[0117] In some alternative embodiments, the length of the filamentous boehmite whiskers is 5 μm to 15 μm, the diameter of the filamentous boehmite whiskers is 0.2 μm to 2.0 μm, and the aspect ratio of the filamentous boehmite whiskers is 5 to 20.
[0118] In these embodiments, the filamentous boehmite with a whisker length of 5 μm to 15 μm, a whisker diameter of 0.2 μm to 2.0 μm, and a whisker aspect ratio of 5 to 20 indicates that the filamentous boehmite has a good morphology.
[0119] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national / industry standards; if there is no corresponding national / industry standard, they are performed according to general international standards, conventional conditions, or conditions recommended by the manufacturer.
[0120] Example 1
[0121] like Figure 2 As shown, a method for preparing filamentous pseudoboehmite through static sedimentation and aging includes:
[0122] S1. Carbon dioxide and sodium aluminate solution are subjected to a carbonization reaction to obtain a carbonized liquid containing nanoparticles and micron particles at a temperature of 42℃;
[0123] S2. At a preset volume ratio, water at a preset temperature and a carbonization liquid containing nanoparticles and micron particles are mixed to initially induce the directional growth of nanoparticles to form a filamentous structure, thereby obtaining a mixed slurry containing nanoparticles, filamentous structures, and micron particles; wherein, the temperature of the water is greater than the temperature of the carbonization liquid.
[0124] S3. The mixture containing nanoparticles, filamentous structures and micron particles is subjected to static sedimentation and solid-liquid separation in sequence to separate the micron particles and obtain the supernatant.
[0125] S4. The upper clear liquid is aged to allow the nanoparticles and filamentous structures to grow in a directional manner to form filamentous pseudoboehmite, thus obtaining an aged slurry.
[0126] S501. The aging slurry is subjected to solid-liquid separation to obtain solid-phase aging material;
[0127] S502. Wash the solid-phase aging material to obtain the washing material;
[0128] S503. The washing material is dried to obtain filamentous pseudoboehmite.
[0129] The preset volume ratio is 1:1.0;
[0130] The preset temperature is 70℃.
[0131] The temperature of the mixed slurry is 56℃.
[0132] The aging treatment temperature was 75℃, and the aging treatment time was 4 hours.
[0133] The settling time was 20 minutes.
[0134] The mass concentration of alumina in the carbonization solution is 5.0 g / L.
[0135] Example 2
[0136] Compared to Example 1, the differences in this example are as follows, while the rest are the same:
[0137] The preset volume ratio is 1:2.5;
[0138] The preset temperature is 100℃.
[0139] The temperature of the mixed slurry is 83℃.
[0140] The aging treatment temperature was 80℃, and the aging treatment time was 6 hours.
[0141] The settling time was 30 minutes.
[0142] The mass concentration of alumina in the carbonization solution is 0.5 g / L.
[0143] Example 3
[0144] Compared to Example 1, the differences in this example are as follows, while the rest are the same:
[0145] The preset volume ratio is 1:2.0;
[0146] The preset temperature is 95℃.
[0147] The temperature of the mixed slurry is 77℃.
[0148] The aging treatment temperature was 70℃ and the aging treatment time was 5 hours.
[0149] The settling time was 60 minutes.
[0150] The mass concentration of alumina in the carbonization solution is 6 g / L.
[0151] Example 4
[0152] Compared to Example 1, the differences in this example are as follows, while the rest are the same:
[0153] The preset volume ratio is 1:0.5;
[0154] The preset temperature is 85℃.
[0155] The temperature of the mixed slurry is 56℃.
[0156] The aging treatment temperature was 75℃, and the aging treatment time was 5 hours.
[0157] The settling time was 40 minutes.
[0158] The mass concentration of alumina in the carbonization solution is 3.0 g / L.
[0159] Example 5
[0160] Compared to Example 1, the differences in this example are as follows, while the rest are the same:
[0161] The preset volume ratio is 1:2.0;
[0162] The preset temperature is 70℃.
[0163] The temperature of the mixed slurry is 61℃.
[0164] The aging treatment temperature was 78℃, and the aging treatment time was 6 hours.
[0165] The settling time was 45 minutes.
[0166] The mass concentration of alumina in the carbonization solution is 2.0 g / L.
[0167] Comparative Example 1
[0168] Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same:
[0169] Instead of mixing the carbonization solution with water at a preset temperature and allowing it to settle, the carbonization solution is directly subjected to aging treatment. Specific steps are as follows:
[0170] S1. Carbon dioxide and sodium aluminate solution are subjected to a carbonization reaction to obtain a carbonized liquid containing nanoparticles and micron particles;
[0171] S2. The carbonization liquid is aged to allow the nanoparticles and filamentous structures to grow in a directional manner to form filamentous pseudoboehmite, thus obtaining an aged slurry.
[0172] S3. Separate the aged slurry into solid and liquid phases to obtain a solid aged material;
[0173] S4. Wash the solid-phase aging material to obtain the washing material;
[0174] S5. Dry the washing material to obtain filamentous pseudoboehmite.
[0175] The mass concentration of alumina in the carbonization solution is 2.0 g / L.
[0176] The aging treatment temperature was 78℃, and the aging treatment time was 6 hours.
[0177] Comparative Example 2
[0178] Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same:
[0179] Instead of using static settling, the mixed slurry is directly aged.
[0180] Comparative Example 3
[0181] Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same:
[0182] The preset temperature is the same as the temperature of the carbonization liquid itself.
[0183] Comparative Example 4
[0184] Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same:
[0185] The preset volume ratio is 1:0.2.
[0186] Comparative Example 5
[0187] Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same:
[0188] The preset volume ratio is 1:3.0.
[0189] Relevant experimental and effect data:
[0190] 1. The filamentous pseudoboehmite products from Example 1 and Comparative Example 1 were analyzed and their morphological characteristics were statistically analyzed. The results are as follows: Figure 3 and Figure 4 As shown, by Figure 3 and Figure 4 As can be seen, the method for preparing filamentous pseudoboehmite by static sedimentation and aging provided in this application provides a more uniform morphological distribution and clear filamentous structure in the filamentous pseudoboehmite product, which indicates that the method can obtain filamentous pseudoboehmite products with good morphology.
[0191] 2. The microstructure and impurity content of the filamentous pseudoboehmite products of each embodiment and comparative example were statistically analyzed, and the results are shown in Table 1.
[0192] Table 1. Microstructure and impurity content of the filamentous pseudoboehmite products from each embodiment.
[0193]
[0194] As shown in Table 1, the method for preparing filamentous pseudoboehmite through static sedimentation and aging provided in this application utilizes the differences in the physicochemical properties of the carbonization liquid components and achieves the enrichment and directional growth of target nanoparticles through stepwise processing (hot water temperature control treatment + static sedimentation separation + aging). The final filamentous pseudoboehmite product has a crystallinity of over 50% and a grain size of [missing information]. In addition, the average length of the whiskers in the final filamentous boehmite product is 5.0 μm or more, and the average diameter of the filamentous boehmite product is 0.43 μm; furthermore, the content of trihydrate impurities in the final filamentous boehmite product is 1.0% or less.
[0195] In summary, the embodiments of this application provide a method for preparing filamentous pseudoboehmite through static sedimentation and aging. This method utilizes the differences in the physicochemical properties of the carbonized liquid components and achieves the enrichment and directional growth of target nanoparticles through stepwise processing (hot water temperature control treatment + static sedimentation separation + aging), ultimately obtaining filamentous pseudoboehmite products with good morphology and low impurity content.
[0196] Furthermore, this application provides a method for preparing filamentous pseudoboehmite through static sedimentation and aging. This method, based on a synergistic control system of hot water and carbonization liquid, can construct a directional growth environment for nanoparticles, enabling the preparation of filamentous pseudoboehmite products with high aspect ratios. This method effectively solves the technical problems of uneven morphology and impurity phase interference in traditional processes.
[0197] Furthermore, the filamentous pseudoboehmite provided in this application embodiment has good structural uniformity and can provide a high-performance basic raw material for high-end fields such as catalyst supports and precision adsorption materials.
[0198] Furthermore, the filamentous pseudoboehmite provided in this application embodiment has a crystallinity of 50% to 60% and a grain size maintained at [missing information]. to Furthermore, the crystal phase purity and structural stability of filamentous pseudoboehmite are significantly better than those of traditional hydrothermal methods, which can meet the stringent requirements of high temperature resistance and high stability in fields such as high-temperature catalysis and special ceramics.
[0199] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.
Claims
1. A method for preparing filamentous pseudoboehmite through static sedimentation and aging, the method comprising: Carbon dioxide and sodium aluminate solution are subjected to a carbonization reaction to obtain a carbonized liquid containing nanoparticles and micron-sized particles; A carbonization liquid containing nanoparticles and micron particles is mixed with water at a preset volume ratio of 1:(0.5 to 2.5) and a preset temperature of 70°C to 100°C to initially induce the nanoparticles to grow in a directional manner to form a filamentous structure, thereby obtaining a mixed slurry containing nanoparticles, filamentous structures and micron particles; wherein the temperature of the water is higher than the temperature of the carbonization liquid. The slurry containing nanoparticles, filamentous structures and micron particles is subjected to static sedimentation and solid-liquid separation in sequence to separate the micron particles and obtain the supernatant. The upper clear liquid is aged to allow the nanoparticles and filamentous structures to grow in a directional manner to form filamentous pseudoboehmite, thus obtaining an aged slurry. The aged slurry was post-treated to obtain filamentous pseudoboehmite.
2. The method according to claim 1, characterized in that, The temperature of the mixed slurry is between 55°C and 95°C.
3. The method according to claim 1, characterized in that, The aging treatment is performed at a temperature of 70°C to 80°C for a duration of 4 to 6 hours.
4. The method according to claim 1, characterized in that, The settling time is 15 to 60 minutes.
5. The method according to claim 4, characterized in that, The settling time is 20 to 60 minutes.
6. The method according to claim 1, characterized in that, The mass concentration of alumina in the carbonization liquid is from 0.5 g / L to 6 g / L.
7. The method according to claim 1, characterized in that, The step of post-processing the aged slurry to obtain filamentous pseudoboehmite includes: The aging slurry is subjected to solid-liquid separation to obtain a solid-phase aging material; The solid-phase aging material is washed to obtain a washing material; The washing material is dried to obtain filamentous pseudoboehmite.
8. A filamentous boehmite, wherein the filamentous boehmite is prepared by the method according to any one of claims 1 to 7, wherein the crystallinity of the filamentous boehmite is 50% to 60%, the grain size of the filamentous boehmite is 19 Å to 24 Å, and the mass of the gibbsite in the filamentous boehmite is 0.5% to 1.0% of the mass of the filamentous boehmite.
9. The filamentous pseudoboehmite according to claim 8, characterized in that, The length of the filamentous boehmite whiskers is 5 μm to 15 μm, the diameter of the filamentous boehmite whiskers is 0.2 μm to 2.0 μm, and the aspect ratio of the filamentous boehmite whiskers is 5 to 20.