Dealcoholization method of alcohol-containing aluminum hydroxide slurry and preparation method of aluminum hydroxide

Abstract

The invention relates to the field of aluminum hydroxide preparation, and discloses a dealcoholization method of alcohol-containing aluminum hydroxide slurry and a preparation method of aluminum hydroxide. The method comprises the following steps: contacting alcohol-containing aluminum hydroxide slurry with C6 alkane, extracting to obtain an extraction product containing an oil phase and a water phase, and separating dealcoholized aluminum hydroxide slurry from the water phase of the extraction product. According to the method, the extraction agent is selected, the alcohol content in the alcohol-containing aluminum hydroxide slurry can be reduced to 0.15 wt% or below through simple extraction, meanwhile, the carbon residue value in the finally obtained aluminum hydroxide product is not higher than 0.3 wt%, and the method is very suitable for large-scale industrial preparation of high-purity aluminum hydroxide.

Description

Technical Field

[0001] This invention relates to the field of aluminum hydroxide preparation, specifically to a method for removing alcohol from an alcohol-containing aluminum hydroxide slurry and a method for preparing aluminum hydroxide. Background Technology

[0002] Aluminum hydroxide is widely used in industries such as oil refining, pharmaceuticals, construction, and electronics. With the rapid development of my country's economy and the increasing demand for aluminum hydroxide from various industries, the market size of aluminum hydroxide is also continuously expanding.

[0003] There are many methods for preparing aluminum hydroxide, such as reacting soluble aluminum salts with ammonia, reacting sodium tetrahydroxyaluminate with excess carbon dioxide, and Al... 3+ Reaction with alkaline substances and AlO2 - Aluminum hydroxide can be prepared through various processes, including reactions with acidic substances. However, the aluminum hydroxide prepared by these methods has a relatively low purity, while some fields, such as oil refining catalysts, automotive exhaust treatment catalysts, and fine chemicals, generally require high-purity aluminum hydroxide with a purity of 99.9% or higher.

[0004] The alkoxyaluminum hydrolysis method is currently the main method for preparing high-purity aluminum hydroxide. The production process generally involves reacting an alcohol with aluminum to generate alkoxyaluminum, then hydrolyzing the alkoxyaluminum with water to obtain an aluminum hydroxide slurry, and finally drying the aluminum hydroxide slurry to obtain aluminum hydroxide. However, the aluminum hydroxide slurry obtained after the alkoxyaluminum hydrolysis reaction contains a certain amount of alcohol. Due to the special characteristics of the aluminum hydroxide slurry, this alcohol is difficult to remove using conventional separation methods. If the entrained alcohol in the aluminum hydroxide slurry is not removed, the final aluminum hydroxide will have excessively high carbon residue, affecting its purity and quality. Furthermore, the entrained alcohol will increase the raw material consumption during the aluminum hydroxide preparation process, thereby increasing the production cost.

[0005] Therefore, when preparing high-purity aluminum hydroxide using the existing alkoxyaluminum hydrolysis method, removing alcohol from the alcohol-containing aluminum hydroxide slurry is a key issue in improving the quality of aluminum hydroxide.

[0006] In current industrial production, the most common method for removing alcohols entrained in aluminum hydroxide slurry is filtration and repeated washing. For example, CN107640780A discloses a method for preparing aluminum hydroxide, in which, to obtain high-purity aluminum hydroxide, the aluminum hydroxide slurry after hydrolysis of alkoxyaluminum undergoes three-stage filtration and washing, and then the washing liquid is subjected to distillation extraction to separate the alcohol. However, this method is not only inefficient and complex, but also requires repeated washing at high temperatures, resulting in huge water and energy consumption. In addition, CN113735152A provides a method for removing alcohols entrained in aluminum hydroxide slurry. This method involves passing steam into a preheated aluminum hydroxide slurry containing alcohol for stripping. After stripping, the alcohol entrained in the aluminum hydroxide slurry is carried out by the steam, resulting in alcohol-containing steam, which is then separated from the water by condensation. However, this method requires preheating the entire aluminum hydroxide slurry containing alcohol to 80-96℃, and then using steam at 100-200℃ for stripping, which also consumes a lot of energy. Meanwhile, during the preheating process, aluminum hydroxide will continue to undergo an aging reaction when it remains at a high temperature, which will also have an adverse effect on product quality.

[0007] Given the current state of the process for preparing high-purity aluminum hydroxide via alkoxyaluminum hydrolysis, developing a simple, easy-to-implement, and energy-efficient method for de-alcoholizing alcohol-containing aluminum hydroxide slurry is an important task that urgently needs to be completed. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems of complex and energy-intensive alcohol removal from alcohol-containing aluminum hydroxide slurry, and to provide a new method for removing alcohol from alcohol-containing aluminum hydroxide slurry. The method provided by this invention eliminates the need for repeated overall washing or high-temperature stripping of the alcohol-containing aluminum hydroxide slurry as in existing technologies. By selecting an extractant, the alcohol content in the slurry can be reduced to below 0.15% by weight through simple extraction, while ensuring that the residual carbon value in the final aluminum hydroxide product does not exceed 0.3% by weight. The extractant used not only has strong extraction and separation capabilities for alcohols but also does not affect the quality of the aluminum hydroxide slurry. Furthermore, it allows for convenient separation and reuse of the alcohol. The operation is simple and low-cost, making it ideal for large-scale industrial production of high-purity aluminum hydroxide.

[0009] When preparing high-purity aluminum hydroxide using the alkoxyaluminum hydrolysis method, stringent quality requirements (purity of 99.9% by weight) necessitate minimizing the introduction of other ions and impurities in each process step of existing technologies. Based on this requirement, existing de-alcoholization processes for alcohol-containing aluminum hydroxide slurries either involve repeated multi-stage washing with large amounts of water to reduce the alcohol content, or overall stripping of the slurry to remove entrained alcohol using steam. In other words, to avoid introducing new impurities and ensure the quality of the prepared high-purity aluminum hydroxide, current techniques are primarily limited to using water or steam to remove entrained alcohol from the aluminum hydroxide slurry.

[0010] To address the aforementioned technical problems and the limitations of existing technologies that use water or steam to remove alcohols entrained in aluminum hydroxide slurry, the inventors of this invention, considering the unique alcohol-containing environment of aluminum hydroxide slurry, abandoned the washing and stripping techniques of existing technologies. Instead, they creatively employed extraction of the aluminum hydroxide slurry and, through extensive experimentation, sought an extractant that exhibited excellent alcohol separation performance from alcohol-containing aluminum hydroxide slurry, was itself unlikely to leave residues in the slurry, and could be repeatedly reused. Unexpectedly, it was discovered that using C6 alkanes as extractants for alcohol-containing aluminum hydroxide slurry extraction demonstrated both a strong affinity for alcohols and a strong repellency to the aluminum hydroxide slurry. This resulted in extremely low residue levels after extraction, and even trace amounts did not affect the quality of the aluminum hydroxide, ultimately producing an aluminum hydroxide product that met quality requirements. On the other hand, the hydrocarbon-alcohol system composed of C6 alkanes and alcohols removed from the alcohol-containing aluminum hydroxide slurry used in this invention significantly reduces the separation difficulty and cost compared to the water-alcohol system involved in other technical means. Moreover, C6 alkanes have good chemical inertness, and even if trace amounts remain in the removed alcohol, it does not affect the reuse of the alcohol, enabling repeated recycling of alcohols and hydrocarbons. Thus, this invention is completed.

[0011] The first aspect of the present invention provides a method for removing alcohol from an alcohol-containing aluminum hydroxide slurry, the method comprising contacting the alcohol-containing aluminum hydroxide slurry with C6 alkanes and extracting it to obtain an extraction product containing an oil phase and an aqueous phase, and separating the removed aluminum hydroxide slurry from the aqueous phase of the extraction product.

[0012] Preferably, the dealcoholization method further includes separating an alcohol-alkane mixture from the oil phase of the extract.

[0013] Preferably, the alcohol removal method further includes: distilling the alcohol-alkane mixture to separate the alcohol and C6 alkane.

[0014] Preferably, the de-alcoholization method further includes: recycling the alcohol obtained from the distillation process to prepare aluminum hydroxide, and / or recycling the C6 alkanes obtained from the distillation process to the de-alcoholization of the alcohol-containing aluminum hydroxide slurry.

[0015] Preferably, the dehydrogenated aluminum hydroxide slurry is an aqueous phase with a distance of not less than 0.5 cm between its interface and the oil phase and the aqueous phase; more preferably, the dehydrogenated aluminum hydroxide slurry is an aqueous phase with a distance of not less than 1 cm between its interface and the oil phase and the aqueous phase.

[0016] Preferably, the alcohol-alkane mixture is the oil phase with a distance of not less than 0.5 cm between it and the interface between the oil phase and the water phase; more preferably, the alcohol-alkane mixture is the oil phase with a distance of not less than 1 cm between it and the interface between the oil phase and the water phase.

[0017] Preferably, the dealcoholization method further includes the step of combining the extract product at the interface between the dealcoholized aluminum hydroxide slurry and the alcohol-alkane mixture with the alcohol-containing aluminum hydroxide slurry to be dealcoholized.

[0018] Preferably, the interfacial extract is an extract with a distance of less than 0.5 cm between the interface of the oil phase and the aqueous phase; more preferably, the interfacial extract is an extract with a distance of less than 1 cm between the interface of the oil phase and the aqueous phase.

[0019] Preferably, the C6 alkane is selected from one or more of n-hexane, 2-methylpentane, 3-methylpentane, 2,3-dimethylbutane, and 2,2-dimethylbutane; more preferably, the C6 alkane is n-hexane.

[0020] Preferably, the alcohol is a C1-C10 alkanol; more preferably, it is a C4-C8 alkanol; even more preferably, the alcohol is one or more of n-butanol, n-pentanol, isopentanol, n-hexanol, and isohexanol.

[0021] Preferably, the weight ratio of the alcohol-containing aluminum hydroxide slurry to the C6 alkane is 1:0.1-10, more preferably 1:0.2-1; and even more preferably 1:0.2-0.8.

[0022] Preferably, the contact is carried out under stirring.

[0023] Preferably, the extraction conditions include a temperature of 10-40℃ and a time of 1-20h; more preferably, the extraction conditions include a temperature of 15-30℃ and a time of 8-12h.

[0024] Preferably, the alcohol-containing aluminum hydroxide slurry is derived from the hydrolysis product obtained by hydrolyzing aluminum alkoxide with water.

[0025] Preferably, the alkoxyaluminum is obtained by reacting an alcohol with metallic aluminum.

[0026] Preferably, the alcohol-containing aluminum hydroxide slurry contains less than 10% by weight of alcohol and less than 20% by weight of aluminum hydroxide based on alumina; more preferably, the alcohol content in the alcohol-containing aluminum hydroxide slurry is 0.5-8% by weight and the aluminum hydroxide content based on alumina is 6-15% by weight.

[0027] A second aspect of the present invention provides a method for preparing aluminum hydroxide, the method comprising:

[0028] 1) React alcohol and metallic aluminum to obtain a mixture containing aluminum alkoxy;

[0029] 2) The mixture is subjected to a hydrolysis reaction with water to obtain the hydrolysis reaction product;

[0030] 3) Separate the hydrolysis reaction products to obtain an alcohol-containing aluminum hydroxide slurry;

[0031] 4) The alcohol-containing aluminum hydroxide slurry is subjected to de-alcoholization treatment to obtain de-alcoholized aluminum hydroxide slurry;

[0032] 5) The de-alcoholized aluminum hydroxide slurry is dried.

[0033] The alcohol removal process described in step 4) is carried out according to the alcohol removal method described in the first aspect of the present invention.

[0034] Preferably, in step 1), the molar ratio of metallic aluminum to alcohol is 1:3.2-5.

[0035] Preferably, in step 1), the reaction conditions for alcohol and aluminum include: a temperature of 80-200°C and a time of 0.5-3 hours.

[0036] Preferably, in step 2), the weight ratio of the mixture to water is 1:0.5-10.

[0037] Preferably, in step 2), the conditions for the hydrolysis reaction include: a temperature of 20-90℃ and a time of 0.1-2h.

[0038] Preferably, in step 5), the drying conditions include: a temperature of 100-150°C and a time of 4-48 hours.

[0039] The third aspect of this invention provides the application of the method for removing alcohol from the alcohol-containing aluminum hydroxide slurry described in the first aspect of this invention in the preparation of aluminum hydroxide.

[0040] The above technical solution overcomes the limitations of existing alkoxyaluminum hydrolysis processes for preparing aluminum hydroxide, which use water or steam to remove alcohol from the aluminum hydroxide slurry. It creatively employs C6 alkanes as extractants to remove alcohol from the aluminum hydroxide slurry through extraction. This significantly reduces water and energy consumption associated with repeated washing and stripping in existing technologies while ensuring the production of high-quality aluminum hydroxide. Furthermore, it avoids excessive aging of the aluminum hydroxide slurry at high temperatures during the overall heating process in the stripping method, thus preventing adverse effects on the quality of the aluminum hydroxide.

[0041] Furthermore, the method described in this invention breaks with conventional understanding of the prior art by creatively introducing C6 alkanes. This not only enables the removal of alcohol from aluminum hydroxide slurry with a very high removal rate, reducing the alcohol content in the aluminum hydroxide slurry to below 0.15% by weight after removal, but also reveals that C6 alkanes, especially n-hexane, have a strong repulsive effect on aluminum hydroxide slurry. After removal, they are essentially not left in the aluminum hydroxide slurry, ensuring that the carbon residue value of the prepared aluminum hydroxide does not exceed 0.3% by weight, and that the purity of the separated C6 alkanes and alcohols can reach over 99.5%.

[0042] In addition, the oil phase obtained after extraction (i.e., a mixture of alcohols and alkanes) can achieve a high degree of separation between alcohols and C6 alkanes with low energy consumption, and both can be reused repeatedly.

[0043] The de-alcoholization method for aluminum hydroxide slurry and the preparation method for aluminum hydroxide provided by this invention can not only significantly reduce the energy consumption of de-alcoholization, but also require fewer devices and have a simple process, making it very suitable for large-scale industrial production. Detailed Implementation

[0044] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0045] The first aspect of the present invention provides a method for removing alcohol from an alcohol-containing aluminum hydroxide slurry, the method comprising contacting the alcohol-containing aluminum hydroxide slurry with C6 alkanes and extracting it to obtain an extraction product containing an oil phase and an aqueous phase, and separating the removed aluminum hydroxide slurry from the aqueous phase of the extraction product.

[0046] In this invention, unlike the water washing or stripping methods of the prior art, an extraction method is used to remove alcohol from the alcohol-containing aluminum hydroxide slurry, and C6 alkanes are creatively selected as the extractant to extract the alcohol from the alcohol-containing aluminum hydroxide slurry.

[0047] Regarding the use of C6 alkanes, the inventors discovered during experiments that if alkanes below C5 are used as extractants, even if alcohol extraction can be achieved, due to the special properties of the alcohol-containing aluminum hydroxide slurry, alkanes below C5 will remain in a high amount in the aluminum hydroxide slurry after alcohol removal, resulting in a high carbon residue value of the prepared aluminum hydroxide and affecting the quality of high-purity aluminum hydroxide. If alkanes above C7 are used as extractants, the separation of them from the alcohol in the alcohol-containing aluminum hydroxide slurry after extraction becomes significantly more difficult. For example, n-heptane (C7 alkanes) and n-butanol form an azeotrope when mixed. Under normal pressure, the azeotrope formed by the two is difficult to separate by traditional methods such as distillation, significantly increasing the operational difficulty. In addition, even if n-heptane and n-butanol are separated through complex processing, the purity of the obtained alcohol and alkanes will be significantly reduced, making it impossible to reuse the alcohol and alkanes repeatedly, or the alkanes will be introduced as impurities during subsequent alcohol reuse, resulting in a high impurity content in the final product and affecting the quality of the obtained aluminum hydroxide.

[0048] Furthermore, the inventors discovered during their research that when alkanes with a C7 or higher number of carbon atoms are introduced into the reaction of aluminum hydroxide hydrolysis to produce aluminum hydroxide, the alkanes with a C7 or higher number of carbon atoms act as surfactants, thereby affecting the crystal morphology of aluminum hydroxide and resulting in low quality of the prepared aluminum hydroxide.

[0049] According to the present invention, the C6 alkane refers to an alkane with six carbon atoms, and the C6 alkane can be any straight-chain or branched alkane containing six carbon atoms. For example, the C6 alkane can be selected from one or more of n-hexane, 2-methylpentane, 3-methylpentane, 2,3-dimethylbutane, and 2,2-dimethylbutane. Furthermore, from the perspective of introducing as few impurities as possible, the C6 alkane is preferably selected from one of n-hexane, 2-methylpentane, 3-methylpentane, 2,3-dimethylbutane, and 2,2-dimethylbutane.

[0050] During the research process, the inventors discovered that among C6 alkanes, n-hexane not only has excellent extraction ability for alcohols in the alcohol-containing aluminum hydroxide slurry, but also has extremely strong repellency to the alcohol-containing aluminum hydroxide slurry, leaving almost no residue in the aluminum hydroxide slurry after alcohol removal, thus ensuring a low carbon residue value in the aluminum hydroxide product, and it is also easy to separate from the alcohol by distillation.

[0051] In a particularly preferred embodiment of the present invention, the C6 alkane is n-hexane.

[0052] The alcohol-containing aluminum hydroxide slurry described in the first aspect of this invention is derived from the alcohol-containing aluminum hydroxide slurry produced during the hydrolysis of alkoxyaluminum to produce high-purity aluminum hydroxide. More specifically, the alcohol-containing aluminum hydroxide slurry is derived from the hydrolysis product obtained by hydrolyzing alkoxyaluminum with water, wherein the alkoxyaluminum is obtained by reacting an alcohol with metallic aluminum.

[0053] Furthermore, in this invention, the type of alcohol in the alcohol-containing aluminum hydroxide slurry is determined by the alcohol that reacts with metallic aluminum. This invention does not impose any particular limitation on the alcohol used, as long as it is applicable to the prior art process of preparing aluminum hydroxide via the hydrolysis of alkoxyaluminum.

[0054] The alcohol can be, for example, a C1-C10 alkanol, preferably a C2-C8 alkanol, and more preferably a C4-C8 alkanol. Furthermore, the alcohol is preferably a monohydric alcohol.

[0055] More preferably, the alcohol is one or more selected from n-butanol, n-pentanol, isopentanol, n-hexanol, and isohexanol.

[0056] Particularly preferred is n-hexanol and / or n-butanol.

[0057] According to the present invention, the specific composition of the alcohol-containing aluminum hydroxide slurry is determined by the specific process of producing high-purity aluminum hydroxide by alkoxyaluminum hydrolysis, and the present invention does not particularly limit it. For example, in the alcohol-containing aluminum hydroxide slurry, the alcohol content can be less than 10% by weight, and the aluminum hydroxide content based on alumina can be less than 20% by weight; preferably, in the alcohol-containing aluminum hydroxide slurry, the alcohol content is 0.5-8% by weight, and the aluminum hydroxide content based on alumina is 6-15% by weight.

[0058] The above provides a brief description of the source, composition, and types of alcohols contained in the alcohol-containing aluminum hydroxide slurry. This description is provided only to enable those skilled in the art to better understand the invention and should not be construed as limiting the scope of protection of the invention.

[0059] The following section will describe in detail the specific method for producing high-purity aluminum hydroxide via the hydrolysis of alkoxyaluminum. Referring to the description below, the source, composition, and type of alcohol in the alcohol-containing aluminum hydroxide slurry described in the first aspect of this invention will become clearer, and therefore will not be repeated here.

[0060] The following section provides a detailed description of the method for removing alcohol from aluminum hydroxide containing alcohol, as described in the first aspect of this invention.

[0061] According to a first aspect of the present invention, firstly, an alcohol-containing aluminum hydroxide slurry is contacted with C6 alkane and extracted.

[0062] In this invention, the method of contacting the alcohol-containing aluminum hydroxide slurry with C6 alkanes is not limited; preferably, the contact is carried out under stirring. For example, the alcohol-containing aluminum hydroxide slurry and C6 alkanes can be mixed and stirred to ensure uniform mixing. Uniform mixing is more conducive to the subsequent extraction process.

[0063] According to the present invention, there are no particular requirements for the weight ratio of the alcohol-containing aluminum hydroxide slurry and the C6 alkane, as long as the subsequent extraction can be achieved.

[0064] In this invention, the amount of C6 alkane can be determined based on the amount of alcohol-containing aluminum hydroxide slurry. For example, the weight ratio of the alcohol-containing aluminum hydroxide slurry to the C6 alkane can be 1:0.1-10.

[0065] In a preferred embodiment of the present invention, the weight ratio of the alcohol-containing aluminum hydroxide slurry to the C6 alkane is 1:0.2-1. Particularly preferred is 1:0.2-0.8. This ensures effective extraction, reduces the carbon residue of the obtained aluminum hydroxide, and simultaneously reduces the use of C6 alkane, thereby improving the efficiency of subsequent alcohol and alkane separation.

[0066] Next, the mixture of the aluminum hydroxide slurry containing alcohol and the C6 alkane is extracted. In this invention, there are no particular limitations on the extraction conditions; it can be carried out at room temperature, for example, at a temperature of 10-40°C for 1-20 hours.

[0067] In a preferred embodiment of the present invention, the extraction conditions include a temperature of 15-30°C and a time of 8-12 hours. By performing extraction under these conditions, on the one hand, it ensures that the alcohol in the alcohol-containing aluminum hydroxide slurry fully enters the C6 alkanes, achieving a de-alcoholization effect; on the other hand, the relatively low extraction temperature and short extraction time avoid adverse effects on the quality of the aluminum hydroxide slurry.

[0068] According to the present invention, the extraction yields an extract containing an oil phase and an aqueous phase. The oil phase mainly contains C6 alkanes and alcohols, and the aqueous phase mainly contains dealcoholized aluminum hydroxide slurry.

[0069] Then, according to the purpose of the invention, the de-alcoholized aluminum hydroxide slurry is separated from the aqueous phase of the extraction product.

[0070] In the extraction product of this invention, the aqueous phase containing the dealcoholized aluminum hydroxide slurry is located in the lower layer. However, since there is material disturbance at the interface between the aqueous and oil phases of the extraction product, in order to improve the purity of the obtained dealcoholized aluminum hydroxide slurry, it is preferable to separate the dealcoholized aluminum hydroxide slurry at a certain distance from the interface between the oil and aqueous phases.

[0071] During their research and experimentation, the inventors of this invention discovered that the aqueous phase, where the distance between the interface between the oil phase and the aqueous phase is less than 0.5 cm, may contain small amounts of alcohols and alkanes. Therefore, to improve the purity of the aluminum hydroxide slurry, preferably, the de-alcoholized aluminum hydroxide slurry is an aqueous phase with a distance between the interface between the oil phase and the aqueous phase of not less than 0.5 cm. More preferably, the de-alcoholized aluminum hydroxide slurry is an aqueous phase with a distance between the interface between the oil phase and the aqueous phase of not less than 1 cm. This significantly improves the purity of the aluminum hydroxide slurry and reduces the residual carbon value of the prepared aluminum hydroxide.

[0072] The above steps yield a de-alcoholized aluminum hydroxide slurry.

[0073] To further prepare aluminum hydroxide, the de-alcoholized aluminum hydroxide slurry can be subjected to further solid-liquid separation, drying, and other treatments. Related details will be provided in the second aspect of this invention and will not be repeated here.

[0074] On the other hand, the oil phase of the extraction product of the present invention contains an alcohol-alkane mixture, namely, a mixture of alcohols and C6 alkanes in the aluminum hydroxide slurry containing alcohols. To achieve the recovery of alcohols and alkanes, the de-alcoholization method of the present invention may further include a step of separating the alcohol-alkane mixture from the oil phase of the extraction product.

[0075] In the extraction product of this invention, the oil phase containing the alcohol-alkane mixture is located in the upper layer. However, since there is material disturbance at the interface between the aqueous and oil phases of the extraction product, in order to better achieve the subsequent separation and reuse of alcohols and alkanes and improve the purity of the obtained alcohols and alkanes, it is preferable to separate the alcohol-alkane mixture at a certain distance from the interface between the oil and aqueous phases.

[0076] During their research and experimentation, the inventors of this invention discovered that the oil phase, where the distance between the interface between the oil phase and the aqueous phase is less than 0.5 cm, may contain small amounts of water and aluminum hydroxide slurry. Therefore, preferably, the alcohol-alkane mixture is an oil phase with a distance of not less than 0.5 cm between the interface between the oil phase and the aqueous phase. More preferably, the alcohol-alkane mixture is an oil phase with a distance of not less than 1 cm between the interface between the oil phase and the aqueous phase. This ensures that the resulting alcohol-alkane mixture is free from the contamination of water and aluminum hydroxide slurry, thereby improving the subsequent separation efficiency of alcohols and alkanes and the purity of the obtained alcohols and alkanes.

[0077] In this invention, there is an interface between the oil phase and the aqueous phase of the extract. The extract located at the interface is named the interface extract.

[0078] In one embodiment of the present invention, the interface extraction product is an extraction product whose distance from the interface between the oil phase and the aqueous phase is less than 0.5 cm; preferably, the interface extraction product is an extraction product whose distance from the interface between the oil phase and the aqueous phase is less than 1 cm.

[0079] By defining the interfacial extraction products within the above-mentioned range, the purity of the obtained aluminum hydroxide slurry and alcohol-alkane mixture can be guaranteed, while minimizing the production of interfacial extraction products and improving the overall processing efficiency.

[0080] In this invention, through the preferred embodiments described above, the extraction product is divided from top to bottom into an alcohol-alkane mixture, an interfacial extraction product, and an aluminum hydroxide slurry, and the three parts are separated separately.

[0081] The present invention does not specifically limit the separation order of the above three parts. For example, they can be separated sequentially from top to bottom, that is, first separating the alcohol-alkane mixture in the upper part, then separating the extract product in the middle interface section, and finally separating the aluminum hydroxide slurry in the lower part. Of course, they can also be separated from bottom to top, that is, first separating the aluminum hydroxide slurry in the lower part, then separating the extract product in the middle interface section, and finally separating the alcohol-alkane mixture in the upper part.

[0082] In a preferred embodiment of the present invention, the alcohol-alkane mixture is first separated, then the intermediate interfacial extract is separated, and finally the remaining lower portion is aluminum hydroxide slurry. This minimizes disturbance to the extract, and during the final transfer of the aluminum hydroxide slurry, appropriate stirring can be performed to improve transfer efficiency, while preventing the aluminum hydroxide slurry from adhering to the walls and contaminating the alcohol-alkane mixture.

[0083] According to the present invention, the interfacial extract may contain water, alcohol, C6 alkanes, and aluminum hydroxide slurry. To avoid resource waste, the present invention preferably combines the interfacial extract with the next batch of alcohol-containing aluminum hydroxide slurry to be treated. This not only maximizes resource utilization, but also ensures that even if this portion of the interfacial extract is combined with the next batch of alcohol-containing aluminum hydroxide slurry, the amount of interfacial extract in the next batch of extract (the height of the interfacial extract in the vertical direction) will not further increase, but will remain at a relatively low level, without affecting the subsequent treatment effect and efficiency.

[0084] According to a preferred embodiment of the present invention, the mixture of alcohols and alkanes obtained from the extraction product is further subjected to distillation to separate alcohols and C6 alkanes.

[0085] Furthermore, the distillation process is not particularly limited in this invention. For example, it can be carried out by continuous distillation or batch distillation. Those skilled in the art can determine the distillation scheme appropriately based on the boiling points of the alcohols and C6 alkanes contained therein and the purity requirements of the product, which will not be elaborated here.

[0086] In this invention, since C6 alkanes have a low boiling point, the energy consumed in distilling off C6 alkanes is low. Through distillation, high-purity separation of alcohols and hydrocarbons can be achieved, and heat input can be reduced, thus saving energy.

[0087] Furthermore, according to another preferred embodiment of the present invention, the alcohol removal method further includes the step of recycling the alcohol obtained from the distillation process to the preparation of aluminum hydroxide. By employing the above-described extraction, separation, and distillation, the recovered alcohol has extremely low impurity content and a purity of up to 99.6% by weight or higher. It can be recycled as a raw material in the aluminum hydroxide preparation step, thereby not only maintaining the quality of the subsequent aluminum hydroxide but also achieving resource recycling and increasing economic value.

[0088] Furthermore, according to another preferred embodiment of the present invention, the de-alcoholization method further includes the step of reusing the C6 alkanes separated by distillation in the de-alcoholization treatment of the alcohol-containing aluminum hydroxide slurry. By employing the above-described extraction, separation, and distillation, the recovered C6 alkanes have extremely low impurity content and a purity of up to 99.7% by weight or higher. They can be reused as raw materials in the de-alcoholization treatment of subsequent batches of alcohol-containing aluminum hydroxide slurry. This not only does not reduce the quality of the subsequently prepared aluminum hydroxide but also achieves resource recycling and improves economic value.

[0089] This invention departs from the existing technical approach and concept of removing impurities by relying on water or steam to remove mixed alcohols. Through the alcohol removal method for aluminum hydroxide slurry described in the first aspect of this invention, not only can the alcohol removal of aluminum hydroxide slurry be achieved efficiently and with high quality, but the introduced C6 alkanes will not pollute the entire aluminum hydroxide process; on the contrary, they can be efficiently utilized, recovered, and reused. This significantly improves the alcohol removal effect and efficiency, and substantially reduces the energy consumption and operational difficulty of the alcohol removal process, making it highly suitable for large-scale industrial production.

[0090] A second aspect of the present invention provides a method for preparing aluminum hydroxide, wherein the method includes:

[0091] 1) React alcohol and metallic aluminum to obtain a mixture containing aluminum alkoxy;

[0092] 2) The mixture is subjected to a hydrolysis reaction with water to obtain the hydrolysis reaction product;

[0093] 3) Separate the hydrolysis reaction products to obtain an alcohol-containing aluminum hydroxide slurry;

[0094] 4) The alcohol-containing aluminum hydroxide slurry is subjected to de-alcoholization treatment to obtain de-alcoholized aluminum hydroxide slurry;

[0095] 5) The de-alcoholized aluminum hydroxide slurry is dried.

[0096] The alcohol removal process described in step 4) is carried out according to the alcohol removal method described in the first aspect of the present invention.

[0097] The method for preparing aluminum hydroxide according to the second aspect of the present invention will now be described.

[0098] In step 1), the alcohol and metallic aluminum are first reacted to produce aluminum alkoxy.

[0099] According to the present invention, the alcohol can be any of the alcohols commonly used in the preparation of aluminum hydroxide in the art. For example, the alcohol can be a C1-C10 alkanol, that is, an alcohol in which the alkyl group is an alkyl chain. It can be a straight-chain alkyl group or a branched-chain alkyl group, without any particular limitation.

[0100] Furthermore, the alcohol described in this invention is preferably a monohydric alcohol.

[0101] In this invention, the alcohol is preferably a C2-C8 monoalkanol, and more preferably a C4-C8 monoalkanol.

[0102] More preferably, the alcohol described in this invention is one or more of n-butanol, n-pentanol, isopentanol, n-hexanol, and isohexanol.

[0103] Particularly preferred is n-hexanol and / or n-butanol.

[0104] In step 1) of the present invention, the amount of alcohol can be selected within a wide range based on the amount of aluminum. For example, the molar ratio of aluminum to alcohol can be 1:3.2-5; preferably 1:3.5-4.

[0105] Furthermore, in step 1), the reaction conditions of alcohol and aluminum can be the conventional conditions for the reaction of aluminum alkoxide to aluminum alkoxide in the art, without any particular limitation. For example, the reaction conditions of alcohol and aluminum can include: a temperature of 80-200°C and a time of 0.5-3h; preferably, the reaction conditions of alcohol and aluminum include: a temperature of 110-150°C and a time of 0.8-1.5h.

[0106] Next, in step 2), the mixture is subjected to a hydrolysis reaction with water.

[0107] In step 2), the weight ratio of the mixture to water can be a conventional choice in the art and is not particularly limited. For example, the weight ratio of the mixture to water can be 1:0.5-10; preferably 1:0.8-1.5.

[0108] Furthermore, in step 2), the conditions for the hydrolysis reaction are not particularly limited and can be conventionally chosen in the art. For example, the hydrolysis conditions may include a temperature of 20-90°C and a time of 0.1-2 hours. Preferably, the hydrolysis conditions may include a temperature of 60-90°C and a time of 0.2-1 hours.

[0109] According to a second aspect of the invention, the hydrolysis product generated after the hydrolysis of aluminum alkoxy contains alcohol and aluminum hydroxide slurry.

[0110] Therefore, in step 3), the hydrolysis reaction product is separated to obtain an alcohol-containing aluminum hydroxide slurry.

[0111] In the hydrolysis reaction products, due to the density difference, the alcohol generated after hydrolysis is located on top of the aluminum hydroxide slurry. The alcohol and aluminum hydroxide slurry can be separated by conventional separation methods, and the alcohol can be recycled.

[0112] As a separation method, for example, the upper layer of alcohol can be extracted or poured off from the hydrolysis reaction products to obtain an alcohol-containing aluminum hydroxide slurry. This is a conventional technique in the art, and its detailed description is omitted here to avoid obscuring the spirit of the invention.

[0113] Due to the special properties of alcohol-containing aluminum hydroxide slurry, the alcohol and aluminum hydroxide slurry are difficult to completely separate through simple separation in step 3). A small amount of alcohol still remains in the aluminum hydroxide slurry. That is, the aluminum hydroxide slurry obtained through step 3) is an alcohol-containing aluminum hydroxide slurry.

[0114] Next, in step 4), the alcohol-containing aluminum hydroxide slurry is subjected to de-alcoholization treatment to obtain de-alcoholized aluminum hydroxide slurry.

[0115] Step 4) The method for de-alcoholization is carried out in accordance with the de-alcoholization method for aluminum hydroxide slurry containing alcohol described in the first aspect of the present invention. Its specific content, advantages and effects can be referred to the first aspect of the present invention, and will not be repeated here.

[0116] Through step 4) of the present invention, the alcohol in the alcohol-containing aluminum hydroxide slurry is removed, significantly reducing the alcohol content in the aluminum hydroxide slurry to below 0.15% by weight, preferably below 0.1% by weight. Furthermore, the residual amount of C6 alkanes introduced as an extractant in the resulting de-alcoholized aluminum hydroxide slurry is extremely low, ensuring that the carbon residue in the prepared aluminum hydroxide is below 0.3% by weight (wherein the carbon mainly originates from alcohols and C6 alkanes).

[0117] Next, the dehydrogenated aluminum hydroxide slurry obtained in step 4) is dried to prepare aluminum hydroxide.

[0118] To improve the efficiency of subsequent drying, it is preferable to perform solid-liquid separation on the obtained de-alcoholized aluminum hydroxide slurry before performing the drying process described in step 5) to reduce its water content.

[0119] Here, the solid-liquid separation can be performed using various methods conventional in the art, such as filtration and centrifugation. Here, filtration is preferred for solid-liquid separation of the de-alcoholized aluminum hydroxide slurry.

[0120] Next, the drying process described in step 5) is carried out.

[0121] In this invention, there are no particular limitations on the drying conditions, and conventional drying conditions in the art can be used. For example, the drying conditions may include: a temperature of 100-150°C and a time of 4-48 hours; preferably, the drying conditions may include: a temperature of 100-120°C and a time of 8-16 hours.

[0122] The second aspect of this invention provides a novel solution for the removal of alcohol from an alcohol-containing aluminum hydroxide slurry. This makes the entire aluminum hydroxide preparation process more efficient and streamlined. Alcohols entrained in the slurry can be efficiently separated and reused in the reaction between alcohol and metallic aluminum. Furthermore, C6 alkanes used as extractants can be separated with high purity and reused. In the entire removal-alcoholization process, extraction can be carried out at room temperature (10-40°C). Compared to existing technologies that require repeated washing and stripping, the extraction process of this invention consumes virtually no energy. Subsequent distillation requires only a small amount of heat to vaporize the lower-boiling-point C6 alkanes, achieving the separation of alcohol and alkanes, thus significantly reducing energy consumption.

[0123] The third aspect of this invention provides the application of the method for removing alcohol from the alcohol-containing aluminum hydroxide slurry described in the first aspect of this invention in the preparation of aluminum hydroxide.

[0124] As described above, the de-alcoholization method for aluminum hydroxide containing alcohol described in the first aspect of the present invention does not require overall washing or stripping of the aluminum hydroxide slurry at high temperatures as in the prior art, thus avoiding the deterioration caused by continuous aging of the aluminum hydroxide slurry at high temperatures, and providing a completely new processing path for the preparation of high-purity aluminum hydroxide.

[0125] The present invention will be described in detail below through embodiments.

[0126] In the following examples and comparative examples, the method for determining the carbon residue value of aluminum hydroxide is as follows:

[0127] The aluminum hydroxide sample was placed in the high-frequency induction furnace of the carbon-sulfur analyzer, and oxygen was introduced to burn it at 1600℃. The generated CO2 gas was detected by the built-in infrared spectrometer, and the amount of carbon dioxide generated was calculated based on the intensity of the characteristic peak of the infrared spectrum of CO2. Then, the carbon content in the sample was deduced based on the amount of CO2 generated, and its proportion to the mass of aluminum hydroxide was calculated, thus obtaining the residual carbon value.

[0128] The alcohol content in alcohol-containing aluminum hydroxide slurry and de-alcoholized aluminum hydroxide slurry was tested according to the following method:

[0129] A mass m1 of alcohol-containing aluminum hydroxide slurry or de-alcoholized aluminum hydroxide slurry is placed in a rotary evaporator and heated for evaporation. All the condensed liquid product is collected (if the liquid product separates into layers, deionized water is added to dissolve all the alcohol). The alcohol in the liquid product is then quantitatively analyzed using an Agilent 8860 gas chromatograph to obtain the mass m2 of alcohol in the slurry. The alcohol content in the alcohol-containing aluminum hydroxide slurry or de-alcoholized aluminum hydroxide slurry is then calculated using the following formula:

[0130] Alcohol content = m2 / m1 × 100%

[0131] The purity of n-hexane, n-butanol, and n-hexanol was determined using an Agilent 8860 gas chromatograph.

[0132] Example 1

[0133] 1) Add aluminum shavings and n-hexanol to the reactor at a molar ratio of 1:3.6, and control the temperature at 145℃ to carry out the reaction (in this process, a small amount of aluminum shavings and n-hexanol need to be added first, the temperature is raised to 140℃ to initiate the reaction, and then the remaining aluminum shavings and n-hexanol are slowly added), and react until the aluminum shavings are completely consumed to obtain a n-hexanol solution of aluminum hexoxy.

[0134] 2) At 80℃, the mixture obtained in step 1) is mixed with deionized water at a weight ratio of 1:0.95, and hydrolyzed for 15 min under stirring to obtain the hydrolysis reaction product;

[0135] 3) After the hydrolysis reaction product was allowed to stand for 60 min, it was observed that the hydrolysis reaction product was divided into two layers, with the upper layer being an alcohol phase containing water and the lower layer being a slurry phase. The upper alcohol phase was separated to obtain an alcohol-containing aluminum hydroxide slurry with an aluminum hydroxide content of 9.81% by weight (calculated as aluminum oxide, the same below). The alcohol content is shown in Table 1.

[0136] 4) The alcohol-containing aluminum hydroxide slurry obtained in step 3) is mixed with n-hexane at a weight ratio of 1:0.28. After thorough stirring, the mixture is allowed to stand for 10 hours at 25°C to obtain an extract containing an upper oil phase and a lower aqueous phase.

[0137] Next, the oil phase is extracted from the top of the extract until the distance from the upper interface of the remaining oil phase to the interface between the oil and water phases is 1 cm, resulting in an alcohol-alkane mixture. The remaining extract is then extracted until it reaches 1 cm below the interface between the oil and water phases, resulting in the interfacial extract. Finally, the remaining extract is the de-alcoholized aluminum hydroxide slurry, and its alcohol content is shown in Table 1.

[0138] 5) Filter the dehydrogenated aluminum hydroxide slurry obtained in step 4), and dry the resulting filter cake at 120°C for 12 hours to obtain aluminum hydroxide powder A1, the residual carbon value of which is shown in Table 1.

[0139] The alcohol-alkane mixture obtained in step 4) was distilled to obtain n-hexane and n-hexanol. The purity of the obtained alkane (n-hexane) and alcohol (n-hexanol) is shown in Table 1.

[0140] Example 2

[0141] 1) Add aluminum shavings and n-butanol to the reactor at a molar ratio of 1:3.6, and control the temperature at 115℃ to carry out the reaction (this process requires first adding a small amount of aluminum shavings and n-butanol, raising the temperature to 110℃ to initiate the reaction, and then slowly adding the remaining aluminum shavings and n-butanol) until the aluminum shavings are completely consumed, to obtain a n-butanol solution of aluminum butoxy.

[0142] 2) At 70°C, the mixture obtained in step 1) is mixed with deionized water at a weight ratio of 1:1.28, and hydrolyzed for 15 min under stirring to obtain the hydrolysis reaction product;

[0143] 3) After the hydrolysis reaction product was allowed to stand for 60 min, it was observed that the hydrolysis reaction product was divided into two layers. The upper layer was an alcohol phase containing water, and the lower layer was a slurry phase. After separating the upper alcohol phase, an alcohol-containing aluminum hydroxide slurry with an alumina content of 9.80% by weight was obtained. The alcohol content is shown in Table 1.

[0144] 4) The alcohol-containing aluminum hydroxide slurry obtained in step 3) is mixed with n-hexane at a weight ratio of 1:0.28. After thorough stirring, the mixture is allowed to stand at 30°C for 10 hours to extract the product containing an upper oil phase and a lower aqueous phase.

[0145] Next, the oil phase is extracted from the top of the extract until the distance between the upper interface of the remaining oil phase and the oil-water interface is 1 cm, resulting in an alcohol-alkane mixture. The remaining extract is then extracted until it reaches 1 cm below the oil-water interface, resulting in the interfacial extract. Finally, the remaining extract is the de-alcoholized aluminum hydroxide slurry, and the alcohol content is shown in Table 1.

[0146] 5) Filter the dehydrogenated aluminum hydroxide slurry obtained in step 4), and dry the resulting filter cake at 120°C for 12 hours to obtain aluminum hydroxide powder A2, the residual carbon value of which is shown in Table 1.

[0147] The alcohol-alkane mixture obtained in step 4) was distilled to obtain n-hexane and n-butanol. The purities of the obtained alkane (n-hexane) and alcohol (n-butanol) are shown in Table 1.

[0148] Example 3

[0149] The procedure is carried out according to the method of Example 1, except that...

[0150] In step 4), the weight ratio of the resulting alcohol-containing aluminum hydroxide slurry to n-hexane is 1:0.56.

[0151] Aluminum hydroxide powder A3 was prepared.

[0152] The alcohol content of the alcohol-containing aluminum hydroxide slurry, the alcohol content of the de-alcoholized aluminum hydroxide slurry, the purity of the obtained n-hexane and n-hexanol, and the residual carbon value of aluminum hydroxide powder A3 are shown in Table 1.

[0153] Example 4

[0154] The procedure is carried out according to the method of Example 1, except that...

[0155] In step 4), the weight ratio of the resulting alcohol-containing aluminum hydroxide slurry to n-hexane is 1:1.

[0156] Aluminum hydroxide powder A4 was prepared.

[0157] The alcohol content of the alcohol-containing aluminum hydroxide slurry, the alcohol content of the de-alcoholized aluminum hydroxide slurry, the purity of the obtained n-hexane and n-hexanol, and the residual carbon value of aluminum hydroxide powder A4 are shown in Table 1.

[0158] Example 5

[0159] The procedure is carried out according to the method of Example 1, except that...

[0160] In step 4), the weight ratio of the resulting alcohol-containing aluminum hydroxide slurry to n-hexane is 1:0.15.

[0161] Aluminum hydroxide powder A5 was prepared.

[0162] The alcohol content of the alcohol-containing aluminum hydroxide slurry, the alcohol content of the de-alcoholized aluminum hydroxide slurry, the purity of the obtained n-hexane and n-hexanol, and the residual carbon value of aluminum hydroxide powder A5 are shown in Table 1.

[0163] Example 6

[0164] The procedure is carried out according to the method of Example 1, except that...

[0165] In step 4), the oil phase is extracted from the top of the extract until the distance between the upper interface of the remaining oil phase and the oil-water interface is 0.5 cm, resulting in an alcohol-alkane mixture; the remaining extract is extracted until it reaches 0.5 cm below the oil-water interface, resulting in the interfacial extract; the final remaining extract is the de-alcoholized aluminum hydroxide slurry.

[0166] Aluminum hydroxide powder A6 was prepared.

[0167] The alcohol content of the alcohol-containing aluminum hydroxide slurry, the alcohol content of the de-alcoholized aluminum hydroxide slurry, the purity of the obtained n-hexane and n-hexanol, and the residual carbon value of aluminum hydroxide powder A6 are shown in Table 1.

[0168] Example 7

[0169] The procedure is carried out according to the method of Example 1, except that...

[0170] In step 4), the oil phase is extracted from the top of the extract until the distance between the upper interface of the remaining oil phase and the oil-water interface is 0.3 cm, resulting in an alcohol-alkane mixture; the remaining extract is extracted until it is extracted to a depth of 0.4 cm below the oil-water interface, resulting in the interfacial extract; the final remaining extract is the de-alcoholized aluminum hydroxide slurry.

[0171] Aluminum hydroxide powder A7 was prepared.

[0172] The alcohol content of the alcohol-containing aluminum hydroxide slurry, the alcohol content of the de-alcoholized aluminum hydroxide slurry, the purity of the obtained n-hexane and n-hexanol, and the residual carbon value of aluminum hydroxide powder A7 are shown in Table 1.

[0173] Comparative Example 1

[0174] The procedure is carried out according to the method of Example 1, except that...

[0175] Step 4) is skipped; that is, the alcohol-containing aluminum hydroxide slurry obtained in step 3) is directly filtered and dried in step 5).

[0176] Aluminum hydroxide powder D1 was prepared.

[0177] The alcohol content of the alcohol-containing aluminum hydroxide slurry and the residual carbon value of aluminum hydroxide powder D1 are shown in Table 1.

[0178] Comparative Example 2

[0179] The procedure is carried out according to the method of Example 1, except that...

[0180] Instead of step 4), the alcohol-containing aluminum hydroxide slurry obtained in step 3) is filtered, and the resulting filter cake is washed three times with five times the weight of the filter cake in deionized water at 75°C.

[0181] Then the washed aluminum hydroxide is dried according to the drying conditions described in step 5).

[0182] Aluminum hydroxide powder D2 was prepared.

[0183] The alcohol content of the alcohol-containing aluminum hydroxide slurry and the residual carbon value of aluminum hydroxide powder D2 are shown in Table 1.

[0184] Table 1

[0185]

[0186] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for removing alcohol from an alcohol-containing aluminum hydroxide slurry, characterized in that, The method includes contacting an alcohol-containing aluminum hydroxide slurry with C6 alkanes and extracting it to obtain an extract product containing an oil phase and an aqueous phase, and separating a de-alcoholized aluminum hydroxide slurry from the aqueous phase of the extract product.

2. The dealcoholization method according to claim 1, wherein, The dealcoholization method further includes: separating the alcohol-alkane mixture from the oil phase of the extraction product; Preferably, the alcohol removal method further includes: subjecting the alcohol-alkane mixture to distillation to separate the alcohol and C6 alkane; Preferably, the de-alcoholization method further includes: recycling the alcohol obtained from the distillation process to prepare aluminum hydroxide, and / or recycling the C6 alkanes obtained from the distillation process to the de-alcoholization of the alcohol-containing aluminum hydroxide slurry.

3. The dealcoholization method according to claim 1, wherein, The de-alcoholized aluminum hydroxide slurry is the aqueous phase with a distance of not less than 0.5 cm between its interface and the interface of the oil phase and the aqueous phase; Preferably, the de-alcoholized aluminum hydroxide slurry is the aqueous phase with a distance of not less than 1 cm between it and the interface of the oil phase and the aqueous phase.

4. The dealcoholization method according to claim 2, wherein, The alcohol-alkane mixture is the oil phase with a distance of not less than 0.5 cm between it and the interface between the oil phase and the water phase; Preferably, the alcohol-alkane mixture is the oil phase with a distance of not less than 1 cm between it and the interface between the oil phase and the aqueous phase; Preferably, the de-alcoholization method further includes the step of combining the extract product at the interface between the de-alcoholized aluminum hydroxide slurry and the alcohol-alkane mixture with the alcohol-containing aluminum hydroxide slurry to be de-alcoholized; Preferably, the interfacial extract is an extract that is less than 0.5 cm away from the interface between the oil phase and the aqueous phase. More preferably, the interfacial extract is an extract that is less than 1 cm away from the interface between the oil phase and the aqueous phase.

5. The dealcoholization method according to any one of claims 1-4, wherein, The C6 alkane is selected from one or more of n-hexane, 2-methylpentane, 3-methylpentane, 2,3-dimethylbutane, and 2,2-dimethylbutane; Preferably, the C6 alkane is n-hexane; Preferably, the alcohol is a C1-C10 alkanol; more preferably, it is a C4-C8 alkanol. More preferably, the alcohol is one or more selected from n-butanol, n-pentanol, isopentanol, n-hexanol, and isohexanol.

6. The dealcoholization method according to any one of claims 1-4, wherein, The weight ratio of the alcohol-containing aluminum hydroxide slurry to the C6 alkane is 1:0.1-10, preferably 1:0.2-1, and more preferably 1:0.2-0.8; Preferably, the contact is carried out under stirring; Preferably, the extraction conditions include: a temperature of 10-40℃ and a time of 1-20h; More preferably, the extraction conditions include a temperature of 15-30°C and a time of 8-12 hours.

7. The method according to any one of claims 1-4, wherein, The alcohol-containing aluminum hydroxide slurry is derived from the hydrolysis product obtained by hydrolyzing aluminum alkoxy with water. Preferably, the alkoxyaluminum is obtained by reacting an alcohol with metallic aluminum; Preferably, in the alcohol-containing aluminum hydroxide slurry, the alcohol content is less than 10% by weight, and the aluminum hydroxide content, calculated as alumina, is less than 20% by weight; More preferably, in the alcohol-containing aluminum hydroxide slurry, the alcohol content is 0.5-8% by weight, and the aluminum hydroxide content, calculated as aluminum oxide, is 6-15% by weight.

8. A method for preparing aluminum hydroxide, characterized in that, The method includes: 1) React alcohol and metallic aluminum to obtain a mixture containing aluminum alkoxy; 2) The mixture is subjected to a hydrolysis reaction with water to obtain the hydrolysis reaction product; 3) Separate the hydrolysis reaction products to obtain an alcohol-containing aluminum hydroxide slurry; 4) The alcohol-containing aluminum hydroxide slurry is subjected to de-alcoholization treatment to obtain de-alcoholized aluminum hydroxide slurry; 5) The de-alcoholized aluminum hydroxide slurry is dried. The alcohol removal process in step 4) is carried out according to any one of the alcohol removal methods in claims 1-7.

9. The preparation method according to claim 8, wherein, In step 1), the molar ratio of metallic aluminum to alcohol is 1:3.2-5; Preferably, in step 1), the reaction conditions for the alcohol and aluminum include: a temperature of 80-200°C and a time of 0.5-3 hours; Preferably, in step 2), the weight ratio of the mixture to water is 1:0.5-10; Preferably, in step 2), the conditions for the hydrolysis reaction include: a temperature of 20-90℃ and a time of 0.1-2h; Preferably, in step 5), the drying conditions include: a temperature of 100-150°C and a time of 4-48 hours.

10. The application of the method for removing alcohol from the aluminum hydroxide slurry containing alcohol according to any one of claims 1-7 in the preparation of aluminum hydroxide.

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