Silicon-containing aluminum oxide and preparation method thereof

Abstract

The invention relates to the field of inorganic matter synthesis and catalyst carrier material preparation, and discloses silicon-containing aluminum oxide and a preparation method thereof.The preparation method comprises the following steps that 1, an acidic aluminum salt solution and an alkaline solution are mixed and subjected to a neutralization reaction, and first mixed slurry is obtained; (2) introducing CO2-containing gas into the alkaline silicate solution, and carrying out carbonization reaction to obtain second mixed slurry; (3) mixing the first mixed slurry and the second mixed slurry to obtain third mixed slurry, and performing aging reaction to obtain silicon-containing aluminum hydroxide; and (4) roasting the silicon-containing aluminum hydroxide in the step (3) at high temperature to obtain the silicon-containing aluminum oxide. According to the preparation method of the silicon-containing aluminum oxide, the defects of preparation by independently adopting a neutralization precipitation method are overcome, the required washing and filtering time is shortened, the production efficiency is improved, the preparation method is simple, and the prepared silicon-containing aluminum oxide has relatively large pore volume and pore diameter while the relatively high specific surface area is maintained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of inorganic synthesis and catalyst carrier material preparation, in particular to a silicon-containing alumina and a preparation method thereof. BACKGROUND

[0002] The silicon-containing alumina has certain pore structure, specific surface area and certain acidity, and is commonly used as a carrier material in heterogeneous catalysts. The properties of the silicon-containing alumina carrier can affect the performance of the catalyst, and suitable carrier properties (such as pore structure, specific surface area, acidity, etc.) are the key to developing high-performance catalysts.

[0003] CN102029192A discloses a silicon-containing alumina and a preparation method thereof. An aluminum-containing acidic solution and an alkaline solution are subjected to gelation in a modified clay slurry, and then subjected to aging, filtration, washing and other steps to obtain the silicon-containing alumina. The silicon-containing alumina has a silica content of 1-50%, a pore volume of 0.75-1.10 mL / g, and a specific surface area of 200-370 m 2 / g.

[0004] CN105056928A discloses a preparation method of a silicon-aluminum composite oxide with controllable pore structure. An aluminum source compound and a silicon source compound are neutralized to form a gel at room temperature, and then subjected to hydrothermal aging in an autoclave under certain conditions, followed by solid-liquid separation, washing and drying to obtain a silicon-aluminum composite oxide powder with different pore diameters. The silicon-aluminum composite oxide has an alumina content of 10%-50%, a specific surface area of 300-500 m 2 / g, and a pore volume of 0.8-1.8 mL / g.

[0005] The above method can obtain a silicon-containing alumina with certain pore structure, but the low specific surface area and pore volume of the silicon-containing alumina cannot fully meet the requirements of the carrier properties in the presence of macromolecular components in the petroleum refining process. Moreover, the preparation process of the silicon-containing alumina has the problems of difficulty in filtration and washing, leading to high production cost. SUMMARY

[0006] The present application aims to overcome the problems of low specific surface area and pore volume of the silicon-containing alumina in the prior art, which cannot meet the requirements of the carrier properties, and the difficulty in filtration and washing during the preparation process, leading to high production cost. The present application provides a silicon-containing alumina and a preparation method thereof. The preparation method of the silicon-containing alumina improves the defects of the preparation method using neutralization and precipitation alone, shortens the washing and filtration time, improves the production efficiency, and is simple. The prepared silicon-containing alumina has a high specific surface area, a large pore volume and a large pore diameter.

[0007] To achieve the above object, the present application provides a preparation method of silicon-containing alumina in a first aspect, wherein the preparation method comprises the following steps:

[0008] (1) mixing an acidic aluminum salt solution and a basic solution to perform a neutralization reaction to obtain a first mixed slurry;

[0009] (2) passing a CO2-containing gas into the basic silicate solution to perform a carbonization reaction to obtain a second mixed slurry;

[0010] (3) mixing the first mixed slurry and the second mixed slurry to obtain a third mixed slurry, and performing an aging reaction to obtain silicon-containing aluminum hydroxide;

[0011] (4) performing high-temperature calcination on the silicon-containing aluminum hydroxide of step (3) to obtain silicon-containing alumina.

[0012] The present application provides a preparation method of silicon-containing alumina in a first aspect.

[0013] Through the above technical solution, the following beneficial effects are obtained:

[0014] (1) The preparation method of silicon-containing alumina improves the defects of preparing silicon-containing alumina by using a neutralization precipitation method alone. The silicon-containing aluminum hydroxide precursor mixed slurry is easy to filter and wash, the required washing time is shortened, the production efficiency is improved, the preparation method is simple, green, low-carbon, and the raw materials are cheap and easy to obtain, which is suitable for large-scale industrial production.

[0015] (2) In the present application, preferably, the prepared silicon-containing alumina contains fewer impurities and has a larger pore volume and pore size while maintaining a higher specific surface area. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a schematic diagram of a silicon-containing alumina preparation device.

[0017] Figure 2 is an XRD pattern of silicon-containing aluminum hydroxide prepared in Example 1 and Comparative Example 1;

[0018] Figure 3 is an XRD pattern of silicon-containing alumina prepared in Example 1.

[0019] REFERENCE SIGNS

[0020] 1 - carbonization method reaction kettle 2 - neutralization reaction kettle 3 - intermediate reaction kettle

[0021] 4 - phase separation and washing device 5 - drying device 6 - calcination device

[0022] 7 - basic silicate solution raw material tank 8 - raw gas cylinder 9 - acidic aluminum salt solution raw material tank

[0023] 10-Alkaline solution raw material tank; 11-Aging reaction vessel Detailed Implementation

[0024] 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.

[0025] The first aspect of this invention provides a method for preparing silicon-containing alumina, wherein the preparation method includes the following steps:

[0026] (1) Mix the acidic aluminum salt solution and the alkaline solution to carry out a neutralization reaction to obtain the first mixed slurry;

[0027] (2) CO2 gas is passed into an alkaline silicate solution to carry out a carbonization reaction to obtain a second mixed slurry;

[0028] (3) The first mixed slurry and the second mixed slurry are mixed to obtain the third mixed slurry, and then aged to obtain silicon-containing aluminum hydroxide;

[0029] (4) The silicon-containing aluminum hydroxide from step (3) is calcined at high temperature to obtain silicon-containing aluminum oxide.

[0030] In this invention, the preparation method is simple, the conditions are easy to control, the washing and filtration time required for the whole process is shortened, the production efficiency is improved, and the obtained silicon-containing alumina has fewer impurities, high specific surface area and large pore volume.

[0031] According to the present invention, the type of acidic aluminum salt in the acidic aluminum salt solution is not particularly limited, and can be a 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, and is preferably aluminum sulfate.

[0032] According to the present invention, preferably, the 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 between the two, preferably 30-120 g / L.

[0033] According to the present invention, preferably, the alkaline solution is an alkaline aluminate solution and / or an alkaline precipitant solution.

[0034] In the present application, the type of the alkali aluminate in the alkali aluminate solution is not particularly limited, and a person skilled in the art can select a conventional alkali aluminate. Preferably, the alkali aluminate is sodium aluminate and / or potassium aluminate.

[0035] In the present application, preferably, the concentration of the alkali aluminate solution 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, 220 g / L, 250 g / L, 300 g / L, or any range between any two of them, preferably 150-250 g / L, in terms of aluminum oxide.

[0036] According to the present application, the type of the alkali precipitant in the alkali precipitant solution is not particularly limited, and a person skilled in the art can select a conventional alkali precipitant. Preferably, the alkali precipitant is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, and ammonia.

[0037] In the present application, preferably, the mass fraction of the alkali precipitant in the alkali precipitant solution is 5-60 wt%, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, or any range between any two of them, preferably 20-40 wt%.

[0038] According to the present application, preferably, the conditions of the neutralization reaction in step (1) include that the reaction temperature is 40-90℃, preferably 45-70℃, and the reaction time is 0.1-1 h, preferably 0.15-0.6 h. In the present application, the neutralization reaction is carried out under the above conditions, which can avoid the generation of gibbsite due to local uneven mixing at high pH value, thereby reducing the purity of the product.

[0039] In the present application, the neutralization reaction is a continuous reaction, and the flow ratio of the acidic aluminum salt solution and the alkali solution is controlled so that the pH value of the slurry reaches the desired pH value. The pH value of the first mixed slurry is the pH value of the first mixed slurry obtained after the neutralization reaction is completed.

[0040] According to the present application, preferably, the pH value of the first mixed slurry is 5-7.5, for example, 5, 5.5, 6, 6.5, 7, 7.5, or any range between any two of them, preferably 5.5-7.

[0041] According to the present application, the mass ratio of the acidic aluminum salt solution and the alkali solution is not particularly limited, and the pH value of the first mixed slurry can meet the above range.

[0042] In the present application, the type of the alkali silicate in the alkali silicate solution is not particularly limited, and a person skilled in the art can select a conventional alkali silicate. Preferably, the alkali silicate in the alkali silicate solution is sodium silicate and / or potassium silicate.

[0043] According to the present application, preferably, the concentration of the alkali silicate solution is 10-80 g / L, for example 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L, 65 g / L, 70 g / L, 75 g / L, 80 g / L, or any range between any two of them, preferably 20-70 g / L, based on the silicon dioxide.

[0044] According to the present application, preferably, the volume fraction of the CO2 gas in the CO2-containing gas is 50-100%, for example 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, or any range between any two of them, preferably 60-100%. In the present application, the source of the CO2-containing gas is not particularly limited, and it is a conventional CO2 gas and / or a mixed gas of CO2 gas and air.

[0045] According to the present application, the volume ratio of the CO2-containing gas to the alkali silicate solution is not particularly limited, as long as the pH value of the obtained second mixed solution meets the above-mentioned range. Preferably, in step (2), the volume ratio of the CO2-containing gas to the alkali silicate solution is 2-50:1, preferably 5-40:1. In the present application, the volume of the CO2-containing gas is the volume of the gas under standard atmospheric pressure.

[0046] According to the present application, preferably, the conditions of the carbonation reaction in step (2) include: the reaction temperature is 40-90℃, for example 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, or any range between any two of them, preferably 50-80℃; and the reaction time is 0.1-1 h, preferably 0.15-0.8 h.

[0047] According to the present application, 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 between any two of them, preferably 9-11.

[0048] In the present application, preferably, step (3) obtains a third mixed slurry by mixing the first mixed slurry and the second mixed slurry, and the mixing method and the mixing condition are not particularly limited, and the first mixed slurry and the second mixed slurry can be mixed uniformly, and the first mixed slurry and the second mixed slurry can be added together or separately.

[0049] According to the present application, the use amount of the first mixed slurry and the second mixed slurry is not particularly limited, and the pH value of the third mixed slurry obtained after mixing satisfies the above range, and macroporous volume alumina can be obtained. Preferably, the use amount of the first mixed slurry and the second mixed slurry in step (3) is such that the pH value of the third mixed slurry is 7.5-10, for example, 7.5, 8, 8.5, 9, 9.5, 10, or any range between any two of them, preferably 8-9.5.

[0050] According to the present application, preferably, the conditions of the aging reaction in step (3) include: the aging temperature is 60-200℃, preferably 80-150℃; and the aging time is 0.5-12h, preferably 1-7h.

[0051] In the present application, preferably, after the aging reaction is completed, phase separation, washing and drying of the aging reaction product are further included. The phase separation and washing conditions are not particularly limited. Those skilled in the art can select conventional phase separation and washing conditions. The aging product is subjected to suction filtration 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 application, the phase separation and washing of the slurry containing silicon-containing aluminum hydroxide obtained by the aging reaction require less time. In the present application, the neutral pH value means a pH value of 6.5-7.5.

[0052] According to the present application, the drying condition is not particularly limited, and can be a conventional drying condition in the art. Preferably, the drying condition in step (3) includes: the drying temperature is 100-150℃, preferably 110-140℃; and the drying time is 4-24h, preferably 6-12h.

[0053] According to the present application, preferably, the calcination condition in step (4) includes: the calcination temperature is 400-800℃, preferably 450-700℃; and the calcination time is 0.5-12h, preferably 1-5h. In the present application, under the above conditions, the obtained silicon-containing alumina powder has a high specific surface area, and also has a large pore volume and a large pore size.

[0054] According to a preferred embodiment of the present application, the preparation method is used to prepare a silicon-containing alumina powder with a large pore volume and a large pore size. Figure 1The preparation device shown in the preparation device, the device includes: carbonization method reaction kettle, alkali silicate solution raw material tank, raw material gas cylinder, neutralization reaction kettle, acid aluminum salt solution raw material tank, alkali solution raw material tank, intermediate reaction kettle, aging reaction kettle, phase separation and washing device, drying device and calcination device;

[0055] Among them, the alkali silicate solution raw material tank and the raw material gas cylinder are connected with the feed inlet of the carbonization method reaction kettle, and the acid aluminum salt solution raw material tank and the alkali solution raw material tank are connected with the feed inlet of the neutralization reaction kettle; the discharge outlets of the carbonization method reaction kettle and the neutralization reaction kettle are connected with the feed inlet of the intermediate reaction kettle, the discharge outlet of the intermediate reaction kettle is connected with the feed inlet of the aging reaction kettle, and the discharge outlet of the aging reaction kettle is connected with the phase separation and washing device, the drying device and the calcination device in sequence.

[0056] In the present application, preferably, the ratio of the height to the diameter of the carbonization method reaction kettle is 1-10:1, preferably 2-8:1.

[0057] In the present application, preferably, the ratio of the height to the diameter of the neutralization reaction kettle is 0.5-5:1, preferably 1-3:1.

[0058] In the present application, preferably, the ratio of the height to the diameter of the intermediate reaction kettle is 0.5-5:1, preferably 1-3:1.

[0059] In the present application, preferably, the ratio of the height to the diameter of the aging reaction kettle is 0.5-5:1, preferably 1-3:1.

[0060] In the present application, the ratio of the height to the diameter of the carbonization method reaction kettle, the neutralization reaction kettle, the intermediate reaction kettle and the aging reaction kettle refers to the ratio of the height of the reaction kettle to the diameter of the cross section of the reaction kettle. The diameter of the carbonization method reaction kettle, the neutralization reaction kettle, the intermediate reaction kettle and the aging reaction kettle is not particularly limited, and those skilled in the art can adjust the diameter of the carbonization method reaction kettle, the neutralization reaction kettle, the intermediate reaction kettle and the aging reaction kettle according to the preparation conditions.

[0061] According to the present application, the phase separation and washing device is a device that can perform phase separation and washing in the art. Preferably, the phase separation and washing device is selected from at least one of plate and frame filter press, belt filter and centrifuge, preferably belt filter. If centrifuge is selected, the solid precipitate after centrifugation needs to be reslurried and washed, and the washing water is deionized water.

[0062] According to the present application, 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.

[0063] In the present application, the calcining device is not particularly limited, and high-temperature calcining can be performed in the calcining device. Preferably, the calcining device is a rotary kiln and / or a calcining furnace.

[0064] According to a preferred embodiment of the present application, in Figure 1 The preparation device shown in the preparation of the silicon-containing alumina, the acidic aluminum salt solution is sent into the neutralization reactor 2 through the acidic aluminum salt solution raw material tank 9, the alkaline solution is sent into the neutralization reactor 2 through the alkaline solution raw material tank 10, and the first mixed slurry is obtained by mixing and neutralization reaction in the neutralization reactor 2. The alkaline silicate solution is sent into the carbonation method reactor 1 through the alkaline silicate solution raw material tank 7, and the CO2-containing gas is introduced into the alkaline silicate solution through the raw material gas cylinder 8. The second mixed slurry is obtained by carbonation reaction in the carbonation method reactor 1. The first mixed slurry and the second mixed slurry are mixed in the intermediate reactor 3 to obtain the third mixed slurry, and the third mixed slurry is sent into the aging reactor 11 for aging reaction. The product of the aging reaction is sequentially subjected to phase separation, washing and drying in the phase separation and washing device 4 and the drying device 5 to obtain the silicon-containing aluminum hydroxide. The silicon-containing aluminum hydroxide is sent into the calcining device 6 for high-temperature calcination to obtain the silicon-containing alumina.

[0065] The present application provides a silicon-containing alumina prepared by the preparation method of the first aspect. The silicon-containing alumina prepared by the present application has less impurities, and has a larger pore volume and pore size while maintaining a high specific surface area.

[0066] According to the present application, preferably, the content of SiO2 is 5-50wt%, preferably 10-45wt%, the content of Al2O3 is 50-95wt%, preferably 55-90wt%, and the content of impurities is less than 0.5wt%, preferably less than 0.2wt%, based on the total weight of the silicon-containing alumina.

[0067] In the present application, the impurities in the silicon-containing alumina are substances other than Al2O3 and SiO2, mainly including at least one of Na2O, K2O and SO3. The specific determination method of the main components and impurities of the silicon-containing alumina is as follows: after the sample powder is pressed into a tablet, the characteristic spectral lines of each element are measured by using a 3271 type X-ray fluorescence spectrometer of Japan Rikagaku Denki Kogyo Co., Ltd., and the content of each element is semi-quantitatively analyzed by using an external standard method to obtain Al2O3, SiO2, Na2O, SO3 and other components in the sample.

[0068] According to the present application, preferably, the pore volume of the silicon-containing alumina is 1.2-2.5 mL / g, for example 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, 1.9 mL / g, 2.0 mL / g, 2.1 mL / g, 2.2 mL / g, 2.3 mL / g, 2.4 mL / g, 2.5 mL / g, or any range between any two of them, preferably 1.5-2.3 mL / g.

[0069] In the present application, the specific surface area and pore volume, average pore diameter of the silicon-containing alumina are measured by N2 adsorption-desorption characterization method, specifically: 0.3 g of the silicon-containing alumina powder is pretreated at 350℃ under vacuum for 10 h before testing on a Micromeritics ASAP 2420 adsorption instrument for N2 adsorption-desorption characterization. The specific surface area and pore volume, average pore diameter of the silicon-containing alumina are measured.

[0070] According to the present application, preferably, the specific surface area of the silicon-containing alumina is 350-600 m 2 / g, for example 350 m 2 / g, 360 m 2 / g, 380 m 2 / g, 400 m 2 / g, 420 m 2 / g, 440 m 2 / g, 460 m 2 / g, 480 m 2 / g, 500 m 2 / g, 520 m 2 / g, 540 m 2 / g, 560 m 2 / g, 580 m 2 / g, 600 m 2 / g, or any range between any two of them, preferably 360-560 m 2 / g.

[0071] According to the present application, preferably, the average pore diameter of the silicon-containing alumina 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 between any two of them, preferably 15-25 nm.

[0072] In the present application, the crystal structure of the silicon-containing aluminum hydroxide or the silicon-containing aluminum oxide is characterized by XRD. The XRD characterization method is as follows: a certain amount of silicon-containing aluminum hydroxide or silicon-containing aluminum oxide powder is pressed into a sheet shape, and a Philips XPERT series X-ray powder diffractometer is used to determine the crystal form of the sample. The test conditions are as follows: Cu Kα ray (Kα = 0.154 nm), working current 30 mA, working voltage 40 kV, Ni filter, and scanning range 2θ = 5°-70°.

[0073] The present application will be described in detail below through examples and comparative examples. In the following examples and comparative examples, unless otherwise specified, the reagents used in the present application are commercially available.

[0074] In the following examples and comparative examples, the relative washing speed refers to the washing speed of the filtered aged product using 50 L of deionized water. The relative value is based on Comparative Example 1.

[0075] Example 1

[0076] The diameter of the neutralization reactor 2 is 200 mm, and the height-diameter ratio is 2.5:1. The diameter of the carbonation reactor 1 is 100 mm, and the height-diameter ratio is 4.5:1. The diameter of the intermediate reactor 3 is 250 mm, and the height-diameter ratio is 2:1. The diameter of the aging reactor 11 is 300 mm, and the height-diameter ratio is 3:1.

[0077] (1) The aluminum sulfate solution with a concentration of 50 g / L in terms of aluminum oxide is sent to the neutralization reactor 2 through the acidic aluminum salt solution raw material tank 9, and the sodium aluminate solution with a concentration of 220 g / L in terms of aluminum oxide is sent to the neutralization reactor 2 through the alkaline solution raw material tank 10. 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.

[0078] (2) The sodium silicate solution with a concentration of 60 g / L in terms of silicon dioxide is sent to the carbonation reactor 1 through the alkaline silicate solution raw material tank 7, and the gas with a volume fraction of 99.9% containing CO2 is introduced through the raw gas cylinder 8. The carbonation reaction is carried out at 55°C for 0.5 h, and the gas-liquid volume ratio is 23:1. The pH value of the second mixed slurry is 10.0.

[0079] (3) The first mixed slurry of the neutralization reactor 2 and the second mixed slurry of the carbonation reactor 1 are added to the intermediate reactor 3 to obtain a third mixed slurry with a pH value of 8.6. After the third mixed slurry is sent to the aging reactor 11 and aged at 90°C for 4 hours, it is filtered through the phase separation and washing device 4, washed with 50 L of deionized water, and dried at 120°C for 6 hours through the drying device 5 to obtain the silicon-containing aluminum hydroxide. The relative washing speed of the washing is shown in Table 1.

[0080] (4) The silicon-containing aluminum hydroxide was calcined in the calcining device 6 at 600°C for 3 hours to obtain silicon-containing aluminum oxide.

[0081] The XRD of the silicon-containing aluminum hydroxide is shown in Figure 1, from which it can be seen that characteristic peaks appear at 2θ of 14°, 28°, 38° and 49° in the XRD spectrum, and the aluminum hydroxide in the silicon-containing aluminum hydroxide is pseudoboehmite, Figure 2 Figure 2 The XRD of the silicon-containing aluminum hydroxide is shown in Figure 1, from which it can be seen that characteristic peaks appear at 2θ of 14°, 28°, 38° and 49° in the XRD spectrum, and the aluminum hydroxide in the silicon-containing aluminum hydroxide is pseudoboehmite, Figure 3 Figure 3 The XRD of the silicon-containing aluminum hydroxide is shown in Figure 1, from which it can be seen that characteristic peaks appear at 2θ of 14°, 28°, 38° and 49° in the XRD spectrum, and the aluminum hydroxide in the silicon-containing aluminum hydroxide is pseudoboehmite,

[0082] The N2 adsorption pore properties of the silicon-containing aluminum oxide are shown in Table 1, and the main components are shown in Table 2.

[0083] Comparative Example 1

[0084] An aluminum sulfate solution with a concentration of 50 g / L in terms of aluminum oxide was mixed with a sodium metaaluminate solution with a concentration of 220 g / L in terms of aluminum oxide to obtain a mixed slurry with a pH value of 6.4. Then, a sodium silicate solution with a concentration of 60 g / L in terms of silicon dioxide was added to the mixed solution in the same amount as in Example 1, and the mixed solution was mixed and reacted at 60°C for 0.25 h to obtain a mixed solution. After the mixed solution was aged at 90°C for 4 h, the slurry was filtered and washed with 50 L of deionized water, and then dried at 120°C for 6 h to obtain silicon-containing aluminum hydroxide. The silicon-containing aluminum hydroxide was calcined at 600°C for 3 h to obtain silicon-containing aluminum oxide. The relative washing speed of the washing is shown in Table 1.

[0085] The N2 adsorption pore properties of the silicon-containing aluminum oxide are shown in Table 1, and the main components are shown in Table 2.

[0086] Example 2

[0087] The preparation of the silicon-containing aluminum oxide was carried out in the preparation device of Example 1.

[0088] (1) An aluminum sulfate solution with a concentration of 30 g / L in terms of aluminum oxide was sent into the neutralization reactor 2 through the acidic aluminum salt solution raw material tank 9, and a sodium metaaluminate solution with a concentration of 150 g / L in terms of aluminum oxide was sent into the neutralization reactor 2 through the alkaline solution raw material tank 10, and the two solutions were mixed in the neutralization reactor 2, the reaction temperature was 50°C, and the neutralization reaction was carried out for 0.2 h to obtain a first mixed slurry, and the pH value of the first mixed slurry was 6.5.

[0089] ​​(2) The sodium silicate solution with a concentration of 20 g / L in terms of SiO2 was fed into the carbonation reactor 1 through the raw material tank 7 of the alkaline silicate solution, and the CO2-containing gas with a CO2 volume fraction of 90% was fed through the raw material gas cylinder 8, and the carbonation reaction was carried out at 50°C for 0.5 h, with a gas-to-liquid volume ratio of 9:1, to obtain the second mixed slurry with a pH value of 9.5.

[0090] (3) The first mixed slurry of the neutralization reactor 2 and the second mixed slurry of the carbonation reactor 1 were mixed in the intermediate reactor 3 to obtain the third mixed slurry with a pH value of 8.0. After being fed into the aging reactor 11 and aged at 150°C for 3 h, the aging reaction product was filtered through the phase separation and washing device 4, washed with 50 L of deionized water, and dried at 120°C for 6 h through the drying device 5 to obtain the silicon-containing aluminum hydroxide. The relative washing speed of the washing is shown in Table 1.

[0091] (4) The silicon-containing aluminum hydroxide was calcined at 600°C for 3 h in the calcining device 6 to obtain the silicon-containing aluminum oxide.

[0092] The N2 adsorption pore properties of the silicon-containing aluminum oxide are shown in Table 1, and the main components are shown in Table 2.

[0093] Example 3

[0094] The preparation of the aluminum oxide was carried out in the preparation device of Example 1.

[0095] (1) The aluminum sulfate solution with a concentration of 90 g / L in terms of Al2O3 was fed into the neutralization reactor 2 through the raw material tank 9 of the acidic aluminum salt solution, and the potassium aluminate solution with a concentration of 70 g / L in terms of Al2O3 was fed into the neutralization reactor 2 through the raw material tank 10 of the alkaline solution, and the neutralization reaction was carried out at 70°C for 0.5 h to obtain the first mixed slurry with a pH value of 5.7.

[0096] (2) The sodium silicate solution with a concentration of 10 g / L in terms of SiO2 was fed into the carbonation reactor 1 through the raw material tank 7 of the alkaline silicate solution, and the CO2-containing gas with a CO2 volume fraction of 50% was fed through the raw material gas cylinder 8, and the carbonation reaction was carried out for 0.8 h, with a gas-to-liquid volume ratio of 12.1:1, to obtain the second mixed slurry with a pH value of 8.0.

[0097] (3) The first mixed slurry of the neutralization reactor 2 and the second mixed slurry of the carbonation reactor 1 were fed into the intermediate reactor 3 to obtain the third mixed slurry with a pH value of 9.0. After being fed into the aging reactor 11 and aged at 85°C for 5 h, the third mixed slurry was filtered through the phase separation and washing device 4, washed with 50 L of water, and dried at 120°C for 6 h through the drying device 5 to obtain the silicon-containing aluminum hydroxide. The relative washing speed of the washing is shown in Table 1.

[0098] (4) The silicon-containing aluminum hydroxide was calcined in the calcining device 6 at 650°C for 2 hours to obtain silicon-containing aluminum oxide.

[0099] The N2 adsorption pore properties of the silicon-containing aluminum oxide are shown in Table 1, and the main components are shown in Table 2.

[0100] Example 4

[0101] The preparation of the aluminum oxide was carried out in the preparation device of Example 1.

[0102] (1) The aluminum nitrate solution with a concentration of 60 g / L in terms of aluminum oxide was fed into the neutralization reactor 2 through the acidic aluminum salt solution raw material tank 9, and the ammonia water with a mass fraction of 25 wt% was fed into the neutralization reactor 2 through the alkaline solution raw material tank 10, the addition amount of the aluminum nitrate solution was adjusted, and the neutralization reaction was carried out by mixing, the reaction temperature was 45°C, the reaction time was 0.4 h, and the pH value of the first mixed slurry was 7.0.

[0103] (2) The sodium silicate solution with a concentration of 25 g / L in terms of silicon dioxide was fed into the carbonation method reactor 1 through the alkaline silicate solution raw material tank 7, and the carbonation reaction was carried out by introducing the CO2-containing gas with a volume concentration of 70% through the raw gas cylinder 8, the reaction was carried out at 60°C for 0.7 h, the gas to liquid volume ratio was 20.3:1, and the pH value of the second mixed slurry was 9.0.

[0104] (3) The first mixed slurry of the neutralization reactor 2 and the second mixed slurry of the carbonation method reactor 1 were mixed in the intermediate reactor 3 to obtain a third mixed slurry with a pH value of 8.1. After being fed into the aging reactor 11 and aged at 97°C for 4 hours, the third mixed slurry was filtered through the phase separation and washing device 4, washed with 50 L of water, and dried at 120°C for 6 hours through the drying device 5 to obtain the silicon-containing aluminum hydroxide. The relative washing speed of the washing is shown in Table 1.

[0105] (4) The silicon-containing aluminum oxide was obtained by calcining in the calcining device 6 at 550°C for 3 hours. The N2 adsorption pore properties of the silicon-containing aluminum oxide are shown in Table 1, and the main components are shown in Table 2.

[0106] Example 5

[0107] The silicon-containing aluminum oxide was prepared according to the method of Example 1, except that in step (3), the addition amount of the first mixed slurry was changed, and the pH value of the third mixed slurry obtained was 9.8, which was flowed into the aging reactor 11 for aging reaction, and the other conditions were the same as in Example 1 to obtain the aluminum oxide. The relative washing speed of the washing is shown in Table 1. The N2 adsorption pore properties of the silicon-containing aluminum oxide are shown in Table 1, and the main components are shown in Table 2.

[0108] Example 6

[0109] The silicon-containing alumina was prepared according to the method of Example 1, except that in step (1), the amount of the aluminum sulfate solution was adjusted to obtain a first mixed slurry having a pH of 7.5; and in step (3), the amount of the second mixed slurry was adjusted to obtain a third mixed slurry having a pH of 8.6. The other conditions were the same as in Example 1 to obtain the silicon-containing alumina. The relative washing speed of the washing is shown in Table 1. The N2 adsorption pore properties of the silicon-containing alumina are shown in Table 1, and the main components are shown in Table 2.

[0110] Comparative Example 2

[0111] The silicon-containing alumina was prepared according to the method of Example 1, except that step (1) was not performed, and the aluminum sulfate solution was directly added to the second mixed slurry of step (2) to obtain a third mixed slurry for the aging reaction, specifically:

[0112] (1) A sodium silicate solution having a concentration of 60 g / L of silica was carbonated by bubbling a CO2-containing gas having a volume fraction of 99.9% at 55°C for 0.5 h, with a gas-to-liquid volume ratio of 23:1 to obtain a second mixed slurry having a pH of 10.0.

[0113] (2) An aluminum sulfate solution having a concentration of 50 g / L of alumina was added to the second mixed slurry to obtain a third mixed slurry having a pH of 8.6. After aging at 90°C for 4 h, the aged product was filtered and washed with 50 L of deionized water, and then dried at 120°C for 6 h to obtain silicon-containing aluminum hydroxide. The relative washing speed of the washing is shown in Table 1.

[0114] (3) The silicon-containing aluminum hydroxide was calcined at 600°C for 3 h to obtain silicon-containing alumina. The N2 adsorption pore properties of the silicon-containing alumina are shown in Table 1, and the main components are shown in Table 2.

[0115] Test Example

[0116] The pore volume, specific surface area, and average pore diameter of the prepared silicon-containing alumina were measured by the N2 adsorption and desorption characterization method, and the test results are shown in Table 1.

[0117] During the preparation of the silicon-containing aluminum hydroxide, the relative washing speed (%) of the filtered and aged product was determined by washing the aged product with 50 L of deionized water, and the relative washing speed (%) was obtained by taking the washing speed of Comparative Example 1 as a standard.

[0118] Table 1

[0119]

[0120] The elemental composition and content of the silicon-containing alumina were determined by an X-ray fluorescence spectrometer, and the test results are shown in Table 2.

[0121] Table 2

[0122]

[0123]

[0124] It can be seen from the results in Table 1 and Table 2 that the alumina prepared by using the preparation device and the preparation method provided in the embodiments of the present application has the advantages of simple preparation method, faster washing speed, short washing time, less impurities, high specific surface area, pore volume and pore size, and obviously better effect.

[0125] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and belong to the protection scope of the present application.

Claims

1. A method for preparing silicon-containing alumina, characterized in that, The preparation method includes the following steps: (1) Mix the acidic aluminum salt solution and the alkaline solution to carry out a neutralization reaction to obtain the first mixed slurry; (2) CO2 gas is passed into an alkaline silicate solution to carry out a carbonization reaction to obtain a second mixed slurry; (3) The first mixed slurry and the second mixed slurry are mixed to obtain the third mixed slurry, and then aged to obtain silicon-containing aluminum hydroxide; (4) The silicon-containing aluminum hydroxide from step (3) is calcined at high temperature to obtain silicon-containing aluminum oxide.

2. The preparation method according to claim 1, wherein, 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; Preferably, the concentration of the acidic aluminum salt solution, calculated as alumina, is 20-200 g / L, more preferably 30-120 g / L; Preferably, the alkaline solution is an alkaline aluminate solution and / or an alkaline precipitant solution; Preferably, the alkaline precipitant is selected from at least one of sodium hydroxide, potassium hydroxide, and ammonia water.

3. The preparation method according to claim 1 or 2, wherein, The conditions for the neutralization reaction in step (1) include: a reaction temperature of 40-90℃, preferably 45-70℃; and a reaction time of 0.1-1h, preferably 0.15-0.6h. Preferably, the pH value of the first mixed slurry is 5-7.5, more preferably 5.5-7.

4. The preparation method according to any one of claims 1-3, wherein, The concentration of the alkaline silicate solution, based on silicon dioxide, is 10-80 g / L, preferably 20-70 g / L; Preferably, the alkaline silicate in the alkaline silicate solution is sodium silicate and / or potassium silicate.

5. The preparation method according to any one of claims 1-4, wherein, The CO2-containing gas has a volume fraction of 50-100%, preferably 60-100%. Preferably, in step (2), the volume ratio of the CO2-containing gas to the alkaline silicate solution is 2-50:1, more preferably 5-40:

1.

6. The preparation method according to any one of claims 1-5, wherein, The conditions for the carbonization reaction in step (2) include: a reaction temperature of 40-90℃, preferably 50-80℃; and a reaction time of 0.1-1h, preferably 0.15-0.8h. Preferably, the pH value of the second mixed slurry is 8-12, more preferably 9-11.

7. The preparation method according to any one of claims 1-6, wherein the amount of the first mixed slurry and the second mixed slurry used in step (3) is such that the pH value of the third mixed slurry is 7.5-10, preferably 8-9.

5.

8. The preparation method according to any one of claims 1-7, wherein, The conditions for the aging reaction in step (3) include: an aging temperature of 60-200℃, preferably 80-150℃; and an aging time of 0.5-12h, preferably 1-7h. Preferably, the roasting conditions in step (4) include: a roasting temperature of 400-800℃, preferably 450-700℃; and a roasting time of 0.5-12h, preferably 1-5h.

9. The silicon-containing alumina prepared by the method according to any one of claims 1-8; Preferably, based on the total weight of the silicon-containing alumina, the SiO2 content is 5-50 wt%, preferably 10-45 wt%, the Al2O3 content is 50-95 wt%, preferably 55-90 wt%, and the impurity content is less than 0.5%, preferably less than 0.2%.

10. The silicon-containing alumina according to claim 9, wherein, The pore volume of the silicon-containing alumina is 1.2-2.5 mL / g, preferably 1.5-2.3 mL / g; Preferably, the specific surface area of ​​the silicon-containing alumina is 350-600 m² / g. 2 / g, preferably 360-560m 2 / g; Preferably, the average pore size of the silicon-containing alumina is 12-30 nm, and more preferably 15-25 nm.

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