Preparation device and preparation method of aluminum oxide and prepared aluminum oxide

Abstract

The invention relates to the field of inorganic matter synthesis and catalyst carrier material preparation, and discloses a preparation device and a preparation method of aluminum oxide. The preparation device comprises a carbonization method reaction kettle, an alkaline aluminate solution raw material tank, a raw material gas cylinder, a neutralization reaction kettle, an acidic aluminum salt solution raw material tank, an alkaline solution raw material tank, an intermediate reaction kettle, an aging reaction kettle, a phase separation and washing device, a drying device and a roasting device. According to the preparation device, the defects of preparing aluminum oxide by independently adopting a neutralization precipitation method and a carbonization method are overcome, the production efficiency is high, the preparation method is simple, the process of the preparation method is simple, the time for filtering and washing an intermediate product aluminum hydroxide slurry is shorter, the preparation efficiency is high, raw materials are cheap and easy to obtain, and the preparation device is suitable for large-scale industrial production; the prepared aluminum oxide contains fewer impurities, and has larger pore volume and pore diameter while maintaining higher specific surface area.

Description

Technical Field

[0001] The present invention relates to the fields of inorganic synthesis and catalyst carrier material preparation, and in particular to an aluminum oxide preparation device and method, and the prepared aluminum oxide. Background Art

[0002] Alumina has a certain pore structure and specific surface area, good thermal stability, and is often used as a carrier material for heterogeneous catalysts. The properties of the alumina carrier will affect the performance of the catalyst, and suitable carrier properties (such as pore structure, specific surface area, etc.) are the key to developing high-performance catalysts. At present, the methods for preparing alumina mainly include carbonization method, acid-base neutralization method, alcohol aluminum method, etc. Among them, the alumina prepared by the alcohol aluminum method has high purity and is suitable for various catalysts such as hydrorefining, hydrocracking, lubricating oil isomerization and decondensation, catalytic reforming, etc., but it has disadvantages such as high price and long supply cycle. Among the acid-base neutralization methods, the NaAlO2-Al2(SO4)3 method is one of the main methods for producing alumina. It has low production cost, but impurities (mainly Na + 、SO4 2- The carbonization method for preparing alumina has strict requirements on the neutralization pH value. If the pH value is too high or too low, alumina trihydrate or dawsonite will be easily generated, which will seriously affect the purity and performance of the alumina product. In addition, the intermediate product particles are small, the slurry is difficult to filter, the washing speed is slow, and the industrial production efficiency is low.

[0003] CN100548884C discloses a method for preparing pseudo-boehmite, which involves carbonate a sodium aluminate solution to form a gel, separating the slurry, adding the filter cake to wash water, mixing and beating the mixture, and then heating and aging the mixture. Generally, when preparing pseudo-boehmite using the sodium aluminate-aluminum sulfate method alone, the pH value in industrial equipment may be too high locally, easily forming gibbsite. Therefore, CN100999328A discloses a pseudo-boehmite and its preparation method, which includes two steps: 1) precipitating aluminum from an aqueous solution containing an aluminum compound under acidic conditions sufficient to precipitate aluminum, and separating to obtain an amorphous hydrated aluminum oxide; 2) mixing the amorphous hydrated aluminum oxide, water, and at least one water-soluble base, slurrying the mixture, and aging the slurry at 20°C to 90°C for 0.2 to 6 hours, wherein the amount of base used is such that the pH of the slurry is 6-11.

[0004] Although the above method can obtain alumina with a certain pore structure, the production process still has problems such as difficult filtration and washing, and high production costs. Alumina has shortcomings such as low pore volume and pore diameter, and high impurity content. It still cannot fully meet the requirements of carrier properties for oil refining processes such as residue hydrogenation and catalytic cracking. Summary of the Invention

[0005] The present invention aims to overcome the problems of the prior art, such as small pore volume and pore diameter, high impurity content, complex preparation method, and high production cost, of alumina. The present invention provides an alumina preparation device, a preparation method, and the alumina produced. The preparation device improves the defects of using only the neutralization precipitation method and the carbonization method to prepare alumina, has high production efficiency, a simple preparation method, and a simple preparation process. The intermediate product, aluminum hydroxide slurry, requires shorter filtration and washing time, has high preparation efficiency, and uses inexpensive and readily available raw materials, making it suitable for large-scale industrial production. The alumina produced contains fewer impurities and has a large pore volume and pore diameter while maintaining a high specific surface area.

[0006] To achieve the above-mentioned object, the present invention provides, in a first aspect, an apparatus for preparing aluminum oxide, wherein the apparatus comprises a carbonization reactor, an alkaline aluminate solution raw material tank, a raw material gas cylinder, a neutralization reactor, an acidic aluminum salt solution raw material tank, an alkaline solution raw material tank, an intermediate reactor, an aging reactor, a phase separation and washing device, a drying device, and a calcining device;

[0007] Among them, the alkaline aluminate solution raw material tank and the raw material gas cylinder are connected to the feed port of the carbonization reactor, and the acidic aluminum salt solution raw material tank and the alkaline solution raw material tank are connected to the feed port of the neutralization reactor; the discharge ports of the carbonization reactor and the neutralization reactor are connected to the feed port of the intermediate reactor, the discharge port of the intermediate reactor is connected to the feed port of the aging reactor, and the discharge port of the aging reactor is connected to the phase separation and washing device, the drying device and the roasting device in sequence.

[0008] A second aspect of the present invention provides a method for preparing aluminum oxide, wherein the method comprises the following steps:

[0009] (1) mixing an acidic aluminum salt solution and an alkaline solution, performing a neutralization reaction, and obtaining a first mixed slurry;

[0010] (2) introducing a CO2-containing gas into the first alkaline aluminate solution to perform a carbonization reaction to obtain a second mixed slurry;

[0011] (3) mixing the first mixed slurry and the second mixed slurry to obtain a third mixed slurry, and subjecting the mixture to aging, solid-liquid separation, and drying to obtain aluminum hydroxide;

[0012] (4) calcining the aluminum hydroxide obtained in step (3) at high temperature to obtain aluminum oxide.

[0013] Preferably, the mass ratio of the acidic aluminum salt solution to the alkaline solution is 1-8:1, preferably 2-6:1.

[0014] Preferably, the mass ratio of the first mixed slurry to the second mixed slurry is 0.5-8:1, preferably 1-5:1.

[0015] The third aspect of the present invention provides aluminum oxide produced by the preparation method described in the second aspect.

[0016] Through the above technical solution, the beneficial effects obtained are as follows:

[0017] (1) The method for preparing alumina provided by the present invention combines the carbonization method and the neutralization precipitation method for preparing alumina. The preparation method is simple in process, and the pH value of the second mixed slurry prepared by the carbonization method does not need to be limited to a narrow range. High-purity pseudo-boehmite and alumina can be obtained in the end. The defect of high impurity content of alumina prepared by the neutralization precipitation method is improved. The mixed slurry of the aluminum hydroxide product is easy to filter and wash, and the production efficiency is high.

[0018] (2) In the present invention, preferably, the prepared alumina can increase the pore volume and pore diameter while maintaining the high specific surface area of alumina;

[0019] (3) In the present invention, preferably, when aluminum sulfate is used as the acidic aluminum salt, the content of SO3 in alumina can be greatly reduced, the impurity content can be further reduced, and the emission of sulfur-containing gases during the preparation process can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of an alumina preparation apparatus;

[0021] Figure 2 1 is the XRD pattern of aluminum hydroxide prepared in Example 1, Comparative Example 1 and Comparative Example 2.

[0022] Description of Reference Numerals

[0023] 1-Carbonization reactor 2-Neutralization reactor 3-Intermediate reactor

[0024] 4-Phase separation and washing device 5-Drying device 6-Calcination device

[0025] 7-Alkaline aluminate solution raw material tank 8-Raw material gas cylinder 9-Acidic aluminum salt solution raw material tank

[0026] 10-Alkaline solution raw material tank 11-Aging reactor DETAILED DESCRIPTION

[0027] The endpoints of the ranges and any values 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 endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0028] A first aspect of the present invention provides an apparatus for preparing aluminum oxide, wherein the apparatus comprises a carbonization reactor, an alkaline aluminate solution raw material tank, a raw material gas cylinder, a neutralization reactor, an acidic aluminum salt solution raw material tank, an alkaline solution raw material tank, an intermediate reactor, an aging reactor, a phase separation and washing device, a drying device, and a roasting device;

[0029] Among them, the alkaline aluminate solution raw material tank and the raw material gas cylinder are connected to the feed port of the carbonization reactor, and the acidic aluminum salt solution raw material tank and the alkaline solution raw material tank are connected to the feed port of the neutralization reactor; the discharge ports of the carbonization reactor and the neutralization reactor are connected to the feed port of the intermediate reactor, the discharge port of the intermediate reactor is connected to the feed port of the aging reactor, and the discharge port of the aging reactor is connected to the phase separation and washing device, the drying device and the roasting device in sequence.

[0030] The present invention's production device overcomes the drawbacks of using either the neutralization precipitation or carbonization methods alone to produce alumina. The pH value of the second mixed slurry produced by the carbonization method no longer needs to be restricted to a narrow range, ultimately yielding high-purity pseudo-boehmite and alumina. Furthermore, the high impurity content of alumina produced by the neutralization precipitation method is overcome, and the aluminum hydroxide product mixed slurry is easily filtered and washed, resulting in high production efficiency. The process parameters for producing alumina are controllable, effectively controlling the impurity content in the alumina.

[0031] According to the present invention, preferably, the ratio of the height to the diameter of the carbonization reactor is 1-10:1, such as 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or any range therebetween, preferably 2-8:1.

[0032] In the present invention, the ratio of the height to diameter of the carbonization reactor, neutralization reactor, and aging reactor refers to the ratio of the reactor height to the reactor cross-sectional diameter. There is no particular limitation on the diameter of the carbonization reactor, neutralization reactor, intermediate reactor, and aging reactor. Those skilled in the art can adjust the diameters of the carbonization reactor, neutralization reactor, intermediate reactor, and aging reactor based on the conditions for preparing alumina.

[0033] According to the present invention, the rotation speed of the carbonization reactor is not particularly limited. Preferably, the rotation speed of the carbonization reactor is 50-1000 rpm, more preferably 300-600 rpm. Too slow a rotation speed reduces the utilization rate of the CO2-containing gas.

[0034] In the present invention, preferably, the product of the carbonization reactor flows into the aging reactor in an overflow manner.

[0035] In the present invention, overflow has the conventional meaning in the art, referring to the outflow of liquid and / or gas from a reactor due to excess capacity. By using overflow to allow the products from the carbonization and neutralization reactors to flow into the intermediate reactor, and the overflow of the intermediate reactor products into the aging reactor, it is possible to flexibly control the amount of products added to the carbonization and neutralization reactors, adjust the reaction conditions in the aging reactor, improve reaction efficiency, and ultimately adjust the pore structure and composition of the final alumina product.

[0036] According to the present invention, preferably, the ratio of the height to the diameter of the neutralization reactor is 0.5-5:1, for example, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, or any range therebetween, preferably 1-3:1.

[0037] According to the present invention, the rotation speed of the neutralization reactor is not particularly limited. Preferably, the rotation speed of the neutralization reactor is 50-1000 rpm, preferably 200-600 rpm.

[0038] In the present invention, preferably, the product of the neutralization reactor flows into the intermediate reactor in an overflow manner.

[0039] According to the present invention, the rotation speed of the intermediate reactor is not particularly limited. Preferably, the rotation speed of the neutralization reactor is 50-1000 rpm, preferably 200-600 rpm.

[0040] In the present invention, the product of the intermediate reactor preferably overflows into the aging reactor. According to the present invention, the intermediate reactor is a conventional reaction device in the art. Preferably, the first mixed slurry and the second mixed slurry can be uniformly mixed in the intermediate reactor. Evenly mixing the products of the neutralization reactor and the carbonization reactor in the intermediate reactor and then overflowing into the aging reactor can improve the stability of the resulting alumina product.

[0041] According to the present invention, preferably, the ratio of the height to the diameter of the intermediate reactor is 0.5-5:1, such as 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, or any range therebetween, preferably 1-3: 1. According to the present invention, preferably, the ratio of the height to the diameter of the aging reactor is 0.5-5:1, such as 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, or any range therebetween, preferably 1-3:1.

[0042] According to the present invention, preferably, the rotation speed of the aging reactor is 50-1000 rpm, preferably 200-500 rpm.

[0043] According to the present invention, the phase separation and washing apparatus is a conventional apparatus in the art capable of performing phase separation and washing. Preferably, the phase separation and washing apparatus is selected from at least one of a plate and frame filter press, a belt filter, and a centrifuge, preferably a belt filter. If a centrifuge is used, the solid precipitate after centrifugation must be re-slurried and washed, using deionized water at 60-100°C.

[0044] According to the present invention, the drying method of the drying device is not particularly limited, and those skilled in the art can select a conventional drying method. Preferably, the drying method of the drying device is selected from at least one of spray flash drying, freeze drying, electric heating drying, and steam heating drying.

[0045] In the present invention, the roasting device is not particularly limited, as long as high-temperature roasting can be performed in the roasting device. Preferably, the roasting device is a rotary kiln and / or a roasting furnace.

[0046] A second aspect of the present invention provides a method for preparing aluminum oxide, wherein the method comprises the following steps:

[0047] (1) mixing an acidic aluminum salt solution and an alkaline solution, performing a neutralization reaction, and obtaining a first mixed slurry;

[0048] (2) introducing a CO2-containing gas into the first alkaline aluminate solution to perform a carbonization reaction to obtain a second mixed slurry;

[0049] (3) mixing the first mixed slurry and the second mixed slurry to obtain a third mixed slurry, performing an aging reaction, solid-liquid separation, and drying to obtain aluminum hydroxide;

[0050] (4) calcining the aluminum hydroxide obtained in step (3) at high temperature to obtain aluminum oxide.

[0051] In the present invention, the method for preparing alumina combines the carbonization method and the neutralization precipitation method for preparing alumina. The preparation method has a simple process, and the pH value of the second mixed slurry prepared by the carbonization method does not need to be limited to a narrow range, and high-purity pseudo-boehmite and alumina can be finally obtained; the defect of high impurity content of alumina prepared by the neutralization precipitation method is improved, the mixed slurry of the aluminum hydroxide product is easy to filter and wash, and the production efficiency is high.

[0052] According to the present invention, the type of acidic aluminum salt in the acidic aluminum salt solution is not particularly limited and can be any conventional acidic aluminum salt in the art. Preferably, the acidic aluminum salt in the acidic aluminum salt solution is selected from at least one of aluminum sulfate, aluminum nitrate, and aluminum chloride, preferably aluminum sulfate. Using aluminum sulfate as the acidic aluminum salt can significantly reduce the SO₃ content in alumina, further reducing the impurity content in alumina and reducing sulfur-containing gas emissions during the preparation process.

[0053] According to the present invention, preferably, the mass concentration of the acidic aluminum salt solution, calculated as alumina, is 20-200 g / L, for example, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 100 g / L, 120 g / L, 140 g / L, 160 g / L, 180 g / L, 200 g / L, or any range therebetween, preferably 30-120 g / L.

[0054] According to the present invention, the mass ratio of the acidic aluminum salt solution to the alkaline solution is preferably 1-8:1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, or any range therebetween, preferably 2-6:1. In the present invention, if the mass of the acidic aluminum salt solution is too high or too low, the resulting slurry will have a low solids content and the final alumina product will have a small pore volume.

[0055] According to the present invention, preferably, the alkaline solution is a second alkaline aluminate solution and / or an alkaline precipitant solution.

[0056] According to the present invention, the type of the second alkaline aluminate in the second alkaline aluminate solution is not particularly limited, and a person skilled in the art may select a conventional alkaline aluminate. Preferably, the second alkaline aluminate in the second alkaline aluminate solution is sodium metaaluminate and / or potassium metaaluminate.

[0057] According to the present invention, preferably, the mass concentration of the second alkaline aluminate solution, calculated as alumina, is 50-300 g / L, for example, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 100 g / L, 150 g / L, 200 g / L, 250 g / L, 300 g / L, or any range therebetween, preferably 150-250 g / L. According to the present invention, the type of alkaline precipitant in the alkaline precipitant solution is not particularly limited, and those skilled in the art can select a conventional alkaline precipitant. Preferably, the alkaline precipitant in the alkaline precipitant solution is selected from at least one of sodium hydroxide, potassium hydroxide, and aqueous ammonia.

[0058] According to the present invention, preferably, the mass fraction of the alkaline precipitant in the alkaline precipitant solution is 5-60wt%, for example, 5wt%, 10wt%, 15wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, or any range therebetween, preferably 20-40wt%.

[0059] According to the present invention, preferably, the conditions for the neutralization reaction in step (1) include: a reaction temperature of 30-90°C, preferably 45-70°C; and a reaction time of 0.1-1 hour, preferably 0.15-0.6 hours. In the present invention, conducting the neutralization reaction under the above conditions can avoid the formation of gibbsite due to localized uneven mixing at high pH values, thereby reducing the purity of pseudo-boehmite.

[0060] In the present invention, the neutralization reaction is a continuous reaction, and the reaction equipment is not particularly limited. It is preferably carried out in a reactor. The acidic aluminum salt solution and the alkaline solution enter the neutralization reactor at a certain flow rate, and the ratio of the two flows is controlled to adjust the pH value of the slurry to the desired pH value, and the product flows out of the neutralization reactor.

[0061] According to the present invention, preferably, the pH value of the first mixed slurry is 5-8, such as 5, 5.5, 6, 6.5, 7, 7.5, 8, or any range therebetween, preferably 5.5-7.5.

[0062] According to the present invention, the type of the first alkaline aluminate in the first alkaline aluminate solution is not particularly limited, and those skilled in the art can select conventional alkaline aluminates. Preferably, the first alkaline aluminate in the first alkaline aluminate solution in step (2) is sodium metaaluminate and / or potassium metaaluminate. In the present invention, "first" and "second" are only used to distinguish the alkaline aluminates added in different steps and do not limit the order of addition. The type of the first alkaline aluminate and the type of the second alkaline aluminate can be the same or different.

[0063] According to the present invention, preferably, the mass concentration of the first alkaline aluminate solution, calculated as alumina, is 1-150 g / L, for example, 1 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 100 g / L, 120 g / L, 150 g / L, or any range therebetween, preferably 10-80 g / L.

[0064] According to the present invention, preferably, the volume fraction of CO2 gas in the CO2-containing gas is 10-100%, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or any range therebetween, preferably 60-100%. In the present invention, the CO2-containing gas is a mixture of conventional CO2 gas and air.

[0065] According to the present invention, preferably, the volume ratio of the CO2-containing gas to the first alkaline aluminate solution is 5-200: 1, preferably 10-100: 1. In the present invention, the volume of the CO2-containing gas is the gas volume under standard atmospheric pressure.

[0066] According to the present invention, preferably, the conditions of the carbonization reaction in step (2) include: a reaction temperature of 20-90°C, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or any range therebetween, preferably 30-70°C; and a reaction time of 0.1-1h, preferably 0.15-0.8h.

[0067] According to the present invention, preferably, the pH value of the second mixed slurry is 8-12, for example, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, or any range therebetween, preferably 9-11. In the present invention, the pH value of the second mixed slurry does not need to be limited to around 10. When the pH value is 9 or 11, although the carbonization product contains diaspore or gibbsite, the final product aluminum hydroxide crystal form is all pseudo-boehmite.

[0068] According to the present invention, preferably, the mass ratio of the first mixed slurry to the second mixed slurry is 0.5-8:1, for example, 0.1:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, or any range therebetween, preferably 1-5:1. In the present invention, the first mixed slurry and the second mixed slurry are mixed in the above mass ratio to obtain a third mixed slurry, which can produce large pore volume alumina.

[0069] In the present invention, preferably, in step (3), the first mixed slurry and the second mixed slurry are mixed to obtain a third mixed slurry. The mixing method and mixing conditions are not particularly limited. The first mixed slurry and the second mixed slurry can be mixed evenly. The first mixed slurry and the second mixed slurry can be added together or separately.

[0070] According to a preferred embodiment of the present invention, the first mixed slurry and the second mixed slurry are mixed, and the two slurries react to form a third mixed slurry having a pH between that of the first mixed slurry and the second mixed slurry.

[0071] According to the present invention, preferably, the pH value of the third mixed slurry is 7.5-10, such as 7.5, 8, 8.5, 9, 9.5, 10, or any range therebetween, preferably 8-9.5.

[0072] According to the present invention, preferably, the conditions for the aging reaction in step (3) include: an aging temperature of 60-100°C, preferably 80-98°C; and an aging time of 0.5-12 hours, preferably 1-7 hours. In the present invention, the equipment for the aging reaction is not particularly limited, and those skilled in the art can select conventional equipment capable of performing aging reactions. Preferably, the aging reaction is performed in an aging kettle.

[0073] In the present invention, after the aging reaction is completed, the aging reaction product is preferably subjected to solid-liquid separation and washing. The conditions for the solid-liquid separation and washing are not particularly limited, and those skilled in the art can select conventional solid-liquid separation and washing conditions. The aging product is filtered to obtain a solid filter cake and an aqueous solution, and the solid filter cake is washed with deionized water and then dried. In the present invention, the time required for filtering and washing the aluminum hydroxide slurry obtained by the aging reaction is shortened.

[0074] According to the present invention, the drying conditions are not particularly limited and may be conventional drying conditions in the art. Preferably, the drying conditions in step (3) include: a drying temperature of 100-150°C, preferably 110-140°C; and a drying time of 4-24h, preferably 6-12h.

[0075] According to the present invention, preferably, the calcination conditions in step (4) include: a calcination temperature of 400-800°C, preferably 450-700°C, and a calcination time of 0.5-12 hours, preferably 1-5 hours. In the present invention, calcination under the above conditions produces an alumina powder having a large pore volume and pore diameter while maintaining a high specific surface area.

[0076] According to the present invention, preferably, the method for preparing aluminum oxide is carried out in the preparation device described in the first aspect.

[0077] According to a preferred embodiment of the present invention, Figure 1Alumina is prepared in the alumina preparation apparatus shown. An acidic aluminum salt solution is fed into a neutralization reactor 2 via an acidic aluminum salt solution raw material tank 9, and an alkaline solution is fed into the neutralization reactor 2 via an alkaline solution raw material tank 10. The two solutions are mixed in the neutralization reactor 2 to undergo a neutralization reaction, thereby obtaining a first mixed slurry. A first alkaline aluminate solution is fed into a carbonization reactor 1 via an alkaline aluminate solution raw material tank 7. A CO2-containing gas is introduced into the first alkaline aluminate solution via a raw material gas cylinder 8, and a carbonization reaction is carried out in the carbonization reactor 1 to obtain a second mixed slurry. The first mixed slurry and the second mixed slurry are fed into an intermediate reactor 3 to obtain a third mixed slurry. The third mixed slurry is then fed into an aging reactor 11 for an aging reaction. The product of the aging reaction is sequentially separated, washed, and dried by a phase separation and washing device 4 and a drying device 5 to obtain aluminum hydroxide. The aluminum hydroxide is fed into a calcination device 6 for high-temperature calcination to obtain aluminum oxide.

[0078] In the present invention, the preparation method is green and low-carbon, has high preparation efficiency, uses cheap and readily available raw materials, and is suitable for large-scale industrial production.

[0079] The third aspect of the present invention provides an aluminum oxide prepared by the preparation method of the second aspect. The aluminum oxide prepared by the present invention contains fewer impurities and has a larger pore volume and pore diameter while maintaining a high specific surface area.

[0080] According to the present invention, preferably, the pore volume of the alumina is 0.7-1.8 mL / g, for example, 0.7 mL / g, 0.8 mL / g, 0.9 mL / g, 1 mL / g, 1.1 mL / g, 1.2 mL / g, 1.3 mL / g, 1.4 mL / g, 1.5 mL / g, 1.6 mL / g, 1.7 mL / g, 1.8 mL / g, or any range therebetween, preferably 0.9-1.6 mL / g.

[0081] In the present invention, the pore structure of the alumina is measured by a N2 adsorption-desorption characterization method. Specifically, N2 adsorption-desorption characterization is performed on a Micromeritics ASAP 2420 adsorption instrument. Before the test, about 0.3 g of alumina powder is taken and pretreated at 350°C under vacuum for 10 hours to measure the specific surface area, pore volume and average pore diameter of the alumina.

[0082] According to the present invention, preferably, the specific surface area of the alumina is 200-500m 2 / g, for example 200m 2 / g, 220m 2 / g, 240m 2 / g, 250m 2 / g, 270m 2 / g, 290m 2 / g、300m2 / g、320m 2 / g、350m 2 / g、370m 2 / g, 400m 2 / g, 450m 2 / g、500m 2 / g, or any range between the two, preferably 250-350m 2 / g.

[0083] According to the present invention, preferably, the average pore size of the aluminum oxide is 12-30 nm, for example, 12 nm, 13 nm, 15 nm, 17 nm, 18 nm, 20 nm, 22 nm, 25 nm, 27 nm, 30 nm, or any range therebetween, preferably 15-25 nm.

[0084] According to the present invention, the impurity content of the alumina is preferably less than 1wt%, preferably less than 0.8wt%, and more preferably less than 0.5wt%. In the present invention, the impurities in the alumina include at least one of Na2O, K2O, SiO2, and SO3. The main composition and impurities of alumina are determined by pressing the sample powder into tablets, then using a Rigaku Corporation 3271 X-ray fluorescence spectrometer to measure the characteristic spectral lines of each element. The content of each element is semi-quantitatively analyzed using an external standard method to determine the composition of the sample, such as Al2O3, Na2O, and SO3.

[0085] In the present invention, the crystal structure of aluminum hydroxide is characterized by XRD. The XRD characterization method is as follows: a certain amount of amorphous silicon aluminum powder is pressed into a sheet, and the crystal form of the sample is determined using a Philips XPERT series X-ray powder diffractometer. The test conditions are: Cu Kα radiation (Kα = 0.154nm), an operating current of 30mA, an operating voltage of 40kV, a Ni filter, and a scanning range of 2θ = 5°-70°.

[0086] The present invention will be described in detail below through examples and comparative examples. In the following examples and comparative examples, unless otherwise specified, all reagents used in the present invention are commercially available.

[0087] Example 1

[0088] The diameter of the neutralization reactor 2 is 200 mm, and the height-to-diameter ratio is 2.5:1; the diameter of the carbonization reactor 1 is 100 mm, and the height-to-diameter ratio is 4.5:1; the diameter of the intermediate reactor 3 is 250 mm, and the height-to-diameter ratio is 2:1; the diameter of the aging reactor 11 is 300 mm, and the height-to-diameter ratio is 3:1.

[0089] (1) Aluminum sulfate solution with a mass concentration of 50 g / L is fed into the neutralization reactor 2 through the acidic aluminum salt solution raw material tank 9, and sodium metaaluminate solution with a mass concentration of 220 g / L is fed into the neutralization reactor 2 through the alkaline solution raw material tank 10. The mass ratio of aluminum sulfate solution to alkaline solution is 3.3:1. The rotation speed of the neutralization reactor 2 is 550 rpm. The neutralization reaction is carried out at 60°C for 0.25 h, and the pH value of the first mixed slurry is 6.4.

[0090] (2) A sodium aluminate solution having a mass concentration of 20 g / L is fed into a carbonization reactor 1 through an alkaline aluminate solution raw material tank 7, and a CO2-containing gas having a volume fraction of 100% is introduced into the sodium aluminate solution through a raw material gas cylinder 8. The CO2 and the sodium aluminate solution are carbonized in the carbonization reactor at 30°C for 0.5 h, with a rotation speed of 420 rpm and a gas to liquid volume ratio of 30:1 to obtain a second mixed slurry having a pH value of 10.1.

[0091] (3) The first mixed slurry of the neutralization reactor 2 and the second mixed slurry of the carbonization reactor 1 are flowed into the intermediate reactor 3 by overflow at a mass ratio of 2.3:1, and the rotation speed is 450 rpm.

[0092] The mixture was divided into two parts, and the pH value of the mixed slurry was 8.6. The third mixed slurry was sent to an aging reactor 11 for aging at 95 ° C for 3 hours. The rotation speed of the aging reactor 11 was 230 rpm. The mixture was filtered through a phase separation and washing device 4, which was a belt filter. The mixture was washed with deionized water at 90 ° C. and then spray-flash dried by a drying device 5 to obtain aluminum hydroxide powder.

[0093] (4) The aluminum hydroxide powder is roasted in a roasting furnace of roasting device 6 at 600° C. for 3 hours to obtain aluminum oxide.

[0094] The XRD pattern of aluminum hydroxide is as follows Figure 2 As shown, from Figure 2 It can be seen from the XRD spectrum that characteristic peaks appear at 14°, 28°, 38°, and 49° for 2θ, and the obtained aluminum hydroxide is pseudo-boehmite.

[0095] Comparative Example 1

[0096] Alumina was prepared in the preparation apparatus of Example 1.

[0097] (1) Aluminum sulfate solution with a mass concentration of 50 g / L is fed into the neutralization reactor 2 through the acidic aluminum salt solution raw material tank 9, and sodium metaaluminate solution with a mass concentration of 220 g / L is fed into the neutralization reactor 2 through the alkaline solution raw material tank 10. The mass ratio of aluminum sulfate solution to alkaline solution is 3.3:1. The rotation speed of the neutralization reactor 2 is 550 rpm. The neutralization reaction is carried out at 60°C for 0.25 h. Sodium carbonate is added to adjust the pH value of the mixed solution to obtain a mixed solution with a pH value of 8.6.

[0098] (2) The mixed liquid in the neutralization reactor 2 flows into the aging reactor 11 by overflow. The rotation speed of the aging reactor 11 is 230 rpm. After the mixed liquid is aged at 95°C for 3 hours, it is filtered through the phase separation and washing device 4, which is a belt filter, and washed with 90°C deionized water. Then, it is spray-flash dried through the drying device 5 to obtain aluminum hydroxide powder.

[0099] (3) The aluminum hydroxide powder is roasted in a roasting furnace of roasting device 6 at 600°C for 3 hours to obtain aluminum oxide.

[0100] Comparative Example 2

[0101] Alumina was prepared in the preparation apparatus of Example 1.

[0102] (1) A sodium aluminate solution having a mass concentration of 20 g / L is fed into a carbonization reactor 1 through an alkaline aluminate solution raw material tank 7, and a CO2-containing gas having a volume fraction of 100% is introduced into the sodium aluminate solution through a raw material gas cylinder 8. The CO2 and the sodium aluminate solution are carbonized in the carbonization reactor at 30° C. for 0.5 h, at a rotation speed of 420 rpm and a gas to liquid volume ratio of 30:1, to obtain a second mixed slurry having a pH value of 10.1.

[0103] (2) The mixed liquid in the carbonization reactor 1 is flowed into the aging reactor 11 by overflow. The rotation speed of the aging reactor 11 is 230 rpm. After aging at 95°C for 3 hours, the mixed liquid is filtered through the phase separation and washing device 4, which is a belt filter, and washed with 90°C deionized water. Then, the mixed liquid is spray-flash dried through the drying device 5 to obtain aluminum hydroxide powder.

[0104] (3) The aluminum hydroxide powder is calcined at 600°C for 3 hours in a calcining furnace of calcining device 6 to obtain aluminum oxide. The XRD pattern of the precursor is as follows: Figure 2 As shown, from Figure 2 It can be seen from the figure that the precursor obtained is silnarite.

[0105] Example 2

[0106] Alumina was prepared in the preparation apparatus of Example 1.

[0107] (1) A 30 g / L aluminum sulfate solution was fed into a neutralization reactor 2 via an acidic aluminum salt solution feed tank 9, and a 20 wt% sodium hydroxide solution was mixed and neutralized for 0.2 h via an alkaline solution feed tank 10. The rotation speed of the neutralization reactor 2 was 550 rpm, the reaction temperature was 50° C., and the pH value of the first mixed slurry was 7.5.

[0108] (2) A sodium aluminate solution having a mass concentration of 10 g / L is fed into a carbonization reactor 1 through an alkaline aluminate solution raw material tank 7, and a CO2-containing gas having a volume fraction of 90% is introduced into the sodium aluminate solution through a raw material gas cylinder 8. The CO2 and the sodium aluminate solution are carbonized in the carbonization reactor at 40° C. for 0.4 h, with a rotation speed of 520 rpm and a gas-liquid volume ratio of 25:1 to obtain a second mixed slurry having a pH value of 9.5.

[0109] (3) The first mixed slurry of the neutralization reactor 2 and the second mixed slurry of the carbonization reactor 1 are flowed into the intermediate reactor 3 by overflow at a mass ratio of 1.5:1 at a rotation speed of 550 rpm to obtain a third mixed slurry with a pH value of 8.0. The third mixed slurry is then sent to the aging reactor 11 for aging at 90°C for 4 hours at a rotation speed of 230 rpm. The aging reaction product is sequentially passed through the phase separation and washing device 4, filtered by a belt filter and washed with deionized water at 90°C, and then spray-flash dried by the drying device 5 to obtain aluminum hydroxide powder.

[0110] (4) The aluminum hydroxide powder is calcined at 600° C. for 3 hours in a calcination device 6 to obtain aluminum oxide.

[0111] Example 3

[0112] Alumina was prepared in the preparation apparatus of Example 1.

[0113] (1) Aluminum sulfate solution with a mass concentration of 90 g / L is fed into the neutralization reactor 2 through the acidic aluminum salt solution raw material tank 9, and potassium metaaluminate solution with a mass concentration of 70 g / L is fed into the neutralization reactor 2 through the alkaline solution raw material tank 10. The mass ratio of aluminum sulfate solution to alkaline solution is 3.2:1. The rotation speed of the neutralization reactor 2 is 460 rpm. The neutralization reaction is carried out at 70°C for 0.5 h, and the pH value of the first mixed slurry is 8.

[0114] (2) A sodium aluminate solution having a mass concentration of 20 g / L is fed into a carbonization reactor 1 through an alkaline aluminate solution raw material tank 7, and a CO2-containing gas having a volume fraction of 50% is introduced into the sodium aluminate solution through a raw material gas cylinder 8. The CO2 and the sodium aluminate solution are carbonized in the carbonization reactor at 45° C. for 0.5 h, at a rotation speed of 350 rpm and a gas-liquid volume ratio of 80:1, to obtain a second mixed slurry having a pH value of 10.

[0115] (3) The first mixed slurry of the neutralization reactor 2 and the second mixed slurry of the carbonization reactor 1 are flowed into the intermediate reactor 3 by overflow at a mass ratio of 3.3:1 at a rotation speed of 500 rpm, and mixed to obtain a third mixed slurry with a pH value of 9.0. The third mixed slurry is sent to the aging reactor 11 for aging at 85°C for 5 hours at a rotation speed of 330 rpm, and filtered through the phase separation and washing device 4, which is a belt filter, and washed with 90°C deionized water. Subsequently, the mixture is spray-flash dried through the drying device 5 to obtain aluminum hydroxide powder.

[0116] (4) The aluminum hydroxide powder is roasted at 650° C. in a roasting furnace of roasting device 6 for 2 hours to obtain aluminum oxide.

[0117] Example 4

[0118] Alumina was prepared in the preparation apparatus of Example 1.

[0119] (1) Aluminum nitrate solution with a mass concentration of 60 g / L is fed into the neutralization reactor 2 through the acidic aluminum salt solution raw material tank 9, and ammonia water with a mass fraction of 25 wt% is fed into the neutralization reactor 2 through the alkaline solution raw material tank 10. The mass ratio of aluminum sulfate solution to alkaline solution is 1.5:1. The rotation speed of the neutralization reactor 2 is 370 rpm. In the neutralization reactor 2, the reaction temperature is 40° C., the reaction time is 0.9 h, and the pH value of the first mixed slurry is 9.0.

[0120] (2) A sodium aluminate solution having a mass concentration of 15 g / L is fed into a carbonization reactor 1 through an alkaline aluminate solution raw material tank 7, and a CO2-containing gas having a volume fraction of 70% is introduced into the sodium aluminate solution through a raw material gas cylinder 8. The CO2 and the sodium aluminate solution are carbonized in the carbonization reactor at 65° C. for 0.3 h, a rotation speed of 250 rpm, and a gas-liquid volume ratio of 55:1 to obtain a second mixed slurry having a pH value of 7.0.

[0121] (3) The first mixed slurry of the neutralization reactor 2 and the second mixed slurry of the carbonization reactor 1 are flowed into the intermediate reactor 3 by overflow at a mass ratio of 1.2:1 at a rotation speed of 250 rpm to obtain a third mixed slurry with a pH value of 8.1. The rotation speed of the aging reactor 11 is 330 rpm and the slurry is sent to the aging reactor 11 for aging at 97°C for 4 hours. The slurry is filtered through the phase separation and washing device 4, which is a belt filter, and washed with deionized water at 90°C. The slurry is then spray-flash dried through the drying device 5 to obtain aluminum hydroxide powder.

[0122] (4) The aluminum hydroxide powder is roasted in a roasting furnace of roasting device 6 at 550° C. for 3 hours to obtain aluminum oxide.

[0123] Example 5

[0124] Alumina was prepared in the preparation apparatus of Example 1.

[0125] Alumina was prepared according to the method of Example 1, except that in step (3), the mass of the first mixed slurry was changed, and the mass ratio of the first mixed slurry to the second mixed slurry was 6:1. Other conditions were the same as those of Example 1 to obtain alumina.

[0126] Example 6

[0127] Alumina was prepared in the preparation apparatus of Example 1.

[0128] Alumina was prepared according to the method of Example 1, except that, in step (1), an aluminum sulfate solution having a mass concentration of 50 g / L based on alumina and a sodium aluminate solution having a mass concentration of 220 g / L were mixed in a mass ratio of 7:1. Other conditions were the same as those of Example 1 to obtain alumina.

[0129] Comparative Example 3

[0130] Alumina was prepared in the preparation apparatus of Example 1.

[0131] Alumina was prepared according to the method of Example 1, except that step (1) was not performed and step (2) was performed directly. Subsequently, the slurry from the carbonization reactor overflowed into the intermediate aging reactor 3, and an aluminum sulfate solution of the same concentration as that in Example 1 was added to the intermediate aging reactor 3. The pH value after mixing was the same as that in Example 1. The mixed slurry overflowed into the aging reactor 11 for aging reaction. Other conditions were the same as in Example 1 to obtain alumina.

[0132] Test Case

[0133] The pore volume, specific surface area and average pore diameter of the prepared alumina were measured by N2 adsorption-desorption characterization method, and the test results are shown in Table 1. The elemental composition and content in alumina were determined by X-ray fluorescence spectrometry, and the test results are shown in Table 2.

[0134] Table 1

[0135]

[0136]

[0137] Table 2

[0138]

[0139] The results in Tables 1 and 2 show that the methods of the present invention for preparing alumina are simple, require a short washing time, and produce alumina with fewer impurities, a higher specific surface area, pore volume, and pore diameter, resulting in significantly better performance. Comparative Example 1, which performed only the neutralization reaction, resulted in alumina with a small pore volume and average pore diameter and a high impurity content. Comparative Example 2, which performed only the carbonization reaction, required a long washing time and resulted in alumina with a small pore volume and specific surface area.

[0140] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A device for preparing aluminum oxide, characterized in that: The preparation device includes a carbonization reactor, an alkaline aluminate solution raw material tank, a raw material gas cylinder, a neutralization reactor, an acidic aluminum salt solution raw material tank, an alkaline solution raw material tank, an intermediate reactor, an aging reactor, a phase separation and washing device, a drying device and a roasting device; Among them, the alkaline aluminate solution raw material tank and the raw material gas cylinder are connected to the feed port of the carbonization reactor, and the acidic aluminum salt solution raw material tank and the alkaline solution raw material tank are connected to the feed port of the neutralization reactor; the discharge ports of the carbonization reactor and the neutralization reactor are connected to the feed port of the intermediate reactor, the discharge port of the intermediate reactor is connected to the feed port of the aging reactor, and the discharge port of the aging reactor is connected to the phase separation and washing device, the drying device and the roasting device in sequence.

2. The preparation device according to claim 1, wherein The ratio of the height to the diameter of the carbonization reactor is 1-10:1, preferably 2-8:1; Preferably, the rotation speed of the carbonization reactor is 50-1000 rpm, preferably 300-600 rpm; Preferably, the ratio of the height to the diameter of the neutralization reactor is 0.5-5:1, preferably 1-3:1; Preferably, the rotation speed of the neutralization reactor is 50-1000 rpm, preferably 200-600 rpm; Preferably, the ratio of the height to the diameter of the intermediate reactor is 0.5-5:1, preferably 1-3:1; Preferably, the rotation speed of the intermediate reactor is 50-1000 rpm, preferably 200-600 rpm.

3. The preparation device according to claim 1 or 2, wherein: The ratio of the height to the diameter of the aging reactor is 0.5-5:1, preferably 1-3:1; Preferably, the rotation speed of the aging reactor is 50-1000 rpm, preferably 200-500 rpm; Preferably, the phase separation and washing device is selected from at least one of a plate and frame filter press, a belt filter and a centrifuge; Preferably, the drying method of the drying device is selected from at least one of spray flash drying, freeze drying, electric heating drying and steam heating drying.

4. A method for preparing aluminum oxide, characterized in that: The method comprises the following steps: (1) mixing an acidic aluminum salt solution and an alkaline solution, performing a neutralization reaction, and obtaining a first mixed slurry; (2) introducing a CO2-containing gas into the first alkaline aluminate solution to perform a carbonization reaction to obtain a second mixed slurry; (3) mixing the first mixed slurry and the second mixed slurry to obtain a third mixed slurry, and performing an aging reaction, solid-liquid separation, and drying to obtain aluminum hydroxide; (4) calcining the aluminum hydroxide obtained in step (3) at high temperature to obtain aluminum oxide.

5. The preparation method according to claim 4, wherein The acidic aluminum salt of the acidic aluminum salt solution is selected from at least one of aluminum sulfate, aluminum nitrate and aluminum chloride; Preferably, the mass concentration of the acidic aluminum salt solution is 20-200 g / L, preferably 30-120 g / L, calculated as alumina; Preferably, the mass ratio of the acidic aluminum salt solution to the alkaline solution is 1-8:1, preferably 2-6:

1.

6. The preparation method according to claim 4 or 5, wherein The alkaline solution is a second alkaline aluminate solution and / or an alkaline precipitant solution; Preferably, the second alkaline aluminate of the second alkaline aluminate solution is sodium metaaluminate and / or potassium metaaluminate; Preferably, the mass concentration of the second alkaline aluminate solution is 50-300 g / L, preferably 150-250 g / L, calculated as alumina; Preferably, the alkaline precipitant of the alkaline precipitant solution is selected from at least one of sodium hydroxide, potassium hydroxide and ammonia water; Preferably, the mass fraction of the alkaline precipitant in the alkaline precipitant solution is 5-60 wt%, preferably 20-40 wt%.

7. The preparation method according to any one of claims 4 to 6, wherein The conditions for the neutralization reaction in step (1) include: a reaction temperature of 30-90° C., preferably 45-70° C.; a reaction time of 0.1-1 h, preferably 0.15-0.6 h; Preferably, the pH value of the first mixed slurry is 5-8, preferably 5.5-7.5; Preferably, the mass concentration of the first alkaline aluminate solution is 1-150 g / L, preferably 10-80 g / L, calculated as alumina; Preferably, the volume fraction of CO2 gas in the CO2-containing gas is 10-100%, preferably 60-100%.

8. The preparation method according to any one of claims 4 to 7, wherein The conditions of the carbonization reaction in step (2) include: a reaction temperature of 20-90° C., preferably 30-70° C.; a reaction time of 0.1-1 h, preferably 0.15-0.8 h; Preferably, the volume ratio of the CO2-containing gas to the first alkaline aluminate solution is 5-200:1, preferably 10-100:1; Preferably, the pH value of the second mixed slurry is 8-12, preferably 9-11; Preferably, the mass ratio of the first mixed slurry to the second mixed slurry is 0.5-8:1, preferably 1-5:1; Preferably, the pH value of the third mixed slurry is 7.5-10, preferably 8-9.

5.

9. The preparation method according to any one of claims 4 to 8, wherein The conditions of the aging reaction in step (3) include: an aging temperature of 60-100° C., preferably 80-98° C.; an aging time of 0.5-12 h, preferably 1-7 h; Preferably, the drying conditions in step (3) include: a drying temperature of 100-150° C., preferably 110-140° C.; a drying time of 4-24 hours, preferably 6-12 hours; Preferably, the calcination conditions in step (4) include: a calcination temperature of 400-800°C, preferably 450-700°C; and a calcination time of 0.5-12h, preferably 1-5h.

10. The preparation method according to any one of claims 4 to 9, wherein The method for preparing aluminum oxide is carried out in the preparation device described in any one of claims 1 to 3.

11. Alumina prepared by the preparation method according to any one of claims 4 to 10; Preferably, the pore volume of the alumina is 0.7-1.8 mL / g, preferably 0.9-1.6 mL / g; Preferably, the specific surface area of the alumina is 200-500m 2 / g, preferably 250-350m 2 / g; Preferably, the average pore size of the alumina is 12-30 nm, preferably 15-25 nm; Preferably, the impurity content in the aluminum oxide is less than 1 wt%, preferably less than 0.8 wt%.

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