Spherical alumina and method for producing and use thereof

Abstract

The application relates to the field of spherical alumina preparation, and discloses a kind of spherical alumina and its preparation method and application.A kind of spherical alumina, in the spherical alumina, the hole diameter 6-10nm hole accounts for 10-22% of total pore volume, the hole diameter 10-20nm hole accounts for 50-75% of total pore volume, the hole diameter 20-50nm hole accounts for 10-25% of total pore volume.The spherical alumina has suitable pore structure, and as catalyst carrier, the catalytic performance of catalyst can be significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of spherical alumina preparation, in particular to a kind of spherical alumina and its preparation method and application. BACKGROUND

[0002] Active alumina has suitable pore distribution, good adsorption, thermal stability, surface acidity and large specific surface area, and is one of the most widely used industrial catalyst carriers. In different industrial applications, according to the different processes adopted by the industrial process, the shape and requirements of the alumina carrier are also different. For the moving bed process of continuous reforming, the alumina carrier used by the catalyst needs to be prepared into regular spherical shape in order to reduce the mechanical wear caused by the continuous transportation and cyclic regeneration of the catalyst in the industrial production process. Since the 1990s, people have carried out a lot of research on the preparation method of spherical alumina. The relatively mature methods include rotary balling, spray granulation balling and oil column balling, among which oil column balling is divided into hot oil column forming and oil ammonia column forming.

[0003] Oil column forming is the main method for preparing spherical alumina carrier for moving bed catalyst. Compared with rotary balling and other methods, it has the characteristics of high sphericity of the prepared alumina pellets, uniform particle size, etc. For oil ammonia column forming, aluminum hydroxide (pseudo-boehmite or boehmite) is generally used as raw material, and a proper amount of acid is added to obtain alumina sol by stirring. The alumina sol is dropped into the oil ammonia column for forming. The upper layer of the oil ammonia column is oil layer, and the lower layer is ammonia water layer. The main function of the oil layer is to make the dropped alumina sol into spherical shape. The surface tension of the selected oil and the sol should be large enough to ensure that the sol droplet has good sphericity. The interfacial tension between the ammonia water layer and the oil layer should be small enough to make the sol sphere formed in the oil layer enter the ammonia water layer smoothly without deformation. After the alumina sol droplet is solidified into gel pellets in the ammonia water, the gel pellets are then washed with water, dried and calcined to obtain spherical alumina carrier products.

[0004] In the preparation of the moving bed catalyst for continuous reforming, the properties of the spherical alumina carrier directly determine the performance of the catalyst. The spherical alumina carrier needs to have a large specific surface area to allow the active metal Pt to be highly dispersed. Secondly, the spherical alumina also needs to have a large pore volume to increase the carbon capacity of the catalyst and reduce the deactivation rate of the catalyst. It needs to have sufficient strength and hydrothermal stability to resist mechanical impact and thermal impact during the reaction and regeneration processes, thereby prolonging the service life of the catalyst. In addition, the catalyst also needs to have a suitable bulk density. Suitable bulk density allows lower catalyst loading under the premise of achieving the effect of catalytic reaction and process requirements, thereby reducing the total amount of catalyst and the total platinum amount of the platinum-containing noble metal catalyst, and saving investment costs. In recent years, researchers have found that the pore structure, i.e., the pore size distribution of the spherical alumina carrier, also has a significant impact on the performance of the catalyst. A larger pore diameter is beneficial to improve the diffusion rate of the reactant and product molecules during the reaction process and improve the reaction efficiency. However, an excessively large pore diameter will result in a decrease in the strength of the catalyst. In order to maintain a large specific surface area and high strength, a certain proportion of small pores needs to be retained in the spherical alumina. Therefore, in recent years, more and more attention has been paid to the preparation of spherical alumina carriers with a large specific surface area and a suitable pore diameter distribution.

[0005] CN104148117A discloses a preparation method of an alumina carrier and a catalyst. Two boehmites with different crystal grain sizes are used as raw materials to prepare an alumina carrier. The specific surface area of the alumina carrier determined by nitrogen adsorption is 180-250 m 2 / g, and the pore volume is 0.40-0.8 mL / g. The pore distribution determined by nitrogen adsorption is as follows: the proportion of pores with a diameter of 4-6 nm accounts for 6.0-11.0% of the total pore volume, the proportion of pores with a diameter of 6-20 nm accounts for 88-92% of the total pore volume, and the proportion of pores with a diameter greater than 20 nm accounts for 0.2-2.0% of the total pore volume. The catalyst prepared from the carrier is used for catalytic reforming of naphtha, has a low carbon deposition amount, and has good strength.

[0006] CN107837797A discloses an alumina small ball with a bimodal pore distribution and a preparation method thereof. Pseudo-boehmite, aluminum sol, and water are mixed to obtain an aluminum hydroxide sol. The mass ratio of aluminum / chlorine of the aluminum sol is 1.0-1.4. The obtained aluminum hydroxide sol is mixed with a gelatinizing agent solution and then dropped into a hot oil column to form balls. The formed small balls are taken out, washed, dried, and calcined after aging to obtain alumina small balls. The pore diameter of the alumina small balls shows a clear bimodal distribution at 4-10 nm and 12-20 nm. When the alumina small balls are used for the preparation of a continuous reforming catalyst, the catalyst has a high aromatic yield.

[0007] CN115448338A discloses a macroporous spherical alumina and a preparation method thereof: taking pseudo-boehmite as a raw material, a gel ball is obtained by oil-ammonia column forming, then the gel ball is aged in a fatty alcohol, and then dried and calcined to obtain the macroporous spherical alumina. The spherical alumina carrier has a specific surface area of 200-240 m 2 / g, a pore volume of 0.7-0.9 cm 3 / g, wherein the pores with a pore diameter less than 6 nm account for 0-2% of the total pore volume, the pores with a pore diameter of 6-10 nm account for 4-12% of the total pore volume, the pores with a pore diameter of 10-20 nm account for 86-95% of the total pore volume, and the pores with a pore diameter greater than 20 nm account for 0.1-3% of the total pore volume. The macroporous spherical alumina has a large pore volume and a concentrated macropore distribution. The method uses the gel ball of aluminum hydroxide to expand the pores in an organic solvent, does not use a pore expander, reduces the discharge of three wastes in the production process, and reduces the production cost of the spherical alumina carrier.

[0008] The spherical alumina carrier prepared by the prior art has a pore diameter distribution mainly concentrated in 6-20 nm, which is narrow and limits the application range of some catalysts prepared by using the carrier as a carrier, and affects the catalytic performance of the catalyst. SUMMARY

[0009] The present application aims to overcome the problems of the prior art spherical alumina, and provides a spherical alumina, a preparation method and application thereof. The spherical alumina has a suitable pore structure, and can significantly improve the catalytic performance of a catalyst as a catalyst carrier.

[0010] To achieve the above-mentioned purpose, the first aspect of the present application provides a spherical alumina, wherein the pores with a pore diameter of 6-10 nm account for 10-22% of the total pore volume, the pores with a pore diameter of 10-20 nm account for 50-75% of the total pore volume, and the pores with a pore diameter of 20-50 nm account for 10-25% of the total pore volume.

[0011] Preferably, in the spherical alumina, there is no pore with a pore diameter less than 6 nm.

[0012] Preferably, in the spherical alumina, the pores with a pore diameter greater than 50 nm account for 5% or less of the total pore volume.

[0013] The second aspect of the present application provides a preparation method of a spherical alumina, which comprises the following steps:

[0014] (1) gelatinizing pseudo-boehmite and boehmite to obtain an aluminum hydroxide slurry;

[0015] (2) dropping the aluminum hydroxide slurry into the oil ammonia column to prepare wet aluminum hydroxide pellets, and then drying and calcining the wet aluminum hydroxide pellets;

[0016] wherein the boehmite has a grain size of D (200) / D (002) = 0.5-1.5, D (200) / D (020) = 0.7-1.5, wherein the D (020) , D (200) and D (002) are grain sizes calculated according to the half-peak width of diffraction peaks along the (020), (200) and (002) crystal planes in the X-ray diffraction curve of the boehmite by the Scherrer formula;

[0017] wherein the pseudoboehmite has a grain size of D (120) less than 10 nm, wherein the D (120) is a grain size calculated according to the half-peak width of a diffraction peak along the (120) crystal plane in the X-ray diffraction curve of the pseudoboehmite by the Scherrer formula;

[0018] wherein the total mass of the pseudoboehmite and the boehmite is taken as the basis, the mass content of the pseudoboehmite is 20-50% and the mass content of the boehmite is 50-80%.

[0019] Preferably, the boehmite has a particle size of 0.1-500 μm, preferably 0.1-400 μm.

[0020] Preferably, the boehmite has a D 50 of 40-200 μm, preferably 40-100 μm.

[0021] Preferably, the pseudoboehmite has a particle size of 0.1-300 μm, preferably 0.5-200 μm.

[0022] Preferably, the pseudoboehmite has a D 50 of 5-60 μm, preferably 30-60 μm.

[0023] The third aspect of the present application provides the use of the spherical alumina of the first aspect or the spherical alumina prepared by the method of the second aspect in the preparation of a catalyst.

[0024] The beneficial effects of the present application include:

[0025] The spherical alumina has a suitable pore structure, is used for a catalyst carrier, can significantly improve the catalytic performance of the catalyst, and can improve the carbon capacity of the catalyst during a reaction process, delay the deactivation speed of the catalyst, and increase the service life of the catalyst. When the catalyst prepared by using the spherical alumina as the carrier is used in the field of continuous reforming, the reaction activity and product selectivity can be improved. DETAILED DESCRIPTION

[0026] The endpoints of the ranges and any values claimed herein are not to be understood as being limited to the exact values recited as implicitly included within the range. Ranges can be expressed as from about one particular value to about another particular value. When such a range is expressed, the range is intended to include all values and sub-ranges between the specific values stated.

[0027] The first aspect of the present application provides a spherical alumina, wherein the pores with a pore diameter of 6-10 nm account for 10-22% of the total pore volume, the pores with a pore diameter of 10-20 nm account for 50-75% of the total pore volume, and the pores with a pore diameter of 20-50 nm account for 10-25% of the total pore volume.

[0028] It should be noted that, in the spherical alumina of the present application, the pore diameter of 10 nm is included in the pores with a pore diameter of 10-20 nm, and the pore diameter of 20 nm is included in the pores with a pore diameter of 20-50 nm.

[0029] According to the present application, preferably, in the spherical alumina, the pores with a pore diameter of 6-10 nm account for 12-22% of the total pore volume, the pores with a pore diameter of 10-20 nm account for 55-75% of the total pore volume, and the pores with a pore diameter of 20-50 nm account for 10-20% of the total pore volume. By using this preferred embodiment as a carrier, the catalytic performance of the catalyst can be further improved. When it is applied to the field of continuous reforming, the aromatic yield can be improved.

[0030] According to the present application, preferably, in the spherical alumina, there is no pore with a pore diameter less than 6 nm. By using this preferred embodiment, the pore diameter of the spherical alumina is controlled at a relatively large level, which is beneficial to improving the utilization rate of active metals.

[0031] According to the present application, preferably, in the spherical alumina, the pores with a pore diameter greater than 50 nm account for 5% or less of the total pore volume. By using this preferred embodiment, the pore diameter of the spherical alumina is mainly distributed in the range of 10-50 nm, which is beneficial to ensuring that the spherical alumina carrier has high strength while maintaining a high pore volume.

[0032] The pore size distribution, specific surface area and pore volume of the spherical alumina are determined by an Autosorb-6B full-automatic specific surface area and porosity analyzer of Quantachrome Company of the United States. The determination method is as follows: the spherical alumina sample is vacuum degassed at 1.33 Pa and 300 DEG C for 4 h, and then isothermally adsorbed and desorbed at a liquid nitrogen temperature of 77.4 K (-196 DEG C) by using high-purity nitrogen as the adsorption medium to determine the isotherm; the specific surface area is calculated by using the BET (Brunauer-Emmett-Teller) equation, and the pore volume and pore size distribution are calculated from the desorption isotherm by using the BJH equivalent cylindrical model.

[0033] According to the present application, preferably, the spherical alumina is gamma-alumina. By using this preferred embodiment, it is more favorable to improve the aromatic yield when it is applied to the continuous reforming process.

[0034] The crystal structure of the spherical alumina is measured by X-ray diffraction (XRD).

[0035] According to the present application, preferably, the specific surface area of the spherical alumina is 190-230 m 2 / g.

[0036] According to the present application, preferably, the pore volume of the spherical alumina is 0.6-0.9 cm 3 / g.

[0037] According to the present application, preferably, the average particle size of the spherical alumina is 1.4-1.8 mm.

[0038] The spherical alumina has a suitable specific surface area, pore volume and average particle size, and the catalyst prepared by using the spherical alumina as the carrier and applied to the continuous reforming field is favorable to improve the reaction activity and product selectivity.

[0039] According to the present application, preferably, the sphericity of the spherical alumina is greater than 0.95.

[0040] According to the present application, preferably, the Q 0.95 of the spherical alumina is greater than 95 vol.%, wherein Q 0.95 is the volume ratio of the spherical alumina particles with a sphericity greater than 0.95 in all the spherical alumina particles.

[0041] The sphericity of the spherical alumina and the average particle size are measured by a CAMSIZER multifunctional particle size analyzer of RETSCH, Germany. The ideal sphericity of the alumina pellets is 1, and in general, the sphericity of the alumina pellets is less than 1. The sphericity of the spherical alumina is measured as follows: the average value of the sphericity of the pellets in 50 mL of the sample. The proportion (volume) of the pellets with a sphericity (SPHT) greater than 0.95 in the total pellets in the sample of the alumina pellets is represented by Q 0.95 .

[0042] According to the present application, preferably, the crushing strength of the spherical alumina is 45-80 N / pellet.

[0043] The crushing strength of the spherical alumina is measured by a DL4 type (produced by Dalian Penghui Science and Technology Development Co., Ltd.) particle strength tester. The measurement method is as follows: the alumina pellets are dried at 120℃ for 2 hours, cooled to 25℃ in a desiccator, and 50 pellet samples to be measured are taken out. The relevant measurement parameters of the particle strength tester are set, one pellet sample to be measured is placed on the sample table, the measurement button is clicked, the force rod slowly falls, the pressure is increased to the breaking of the measured pellet sample, and the pressure data is recorded. The pressure data of the 50 measured pellets is obtained, one maximum value and one minimum value are removed, and the average value of the other data is taken as the crushing strength of the test pellet sample.

[0044] The spherical alumina provided by the present application has high sphericity and strength, which can further improve the carbon capacity of the catalyst in the reaction process, reduce the crushing rate of the catalyst in the continuous reaction process, reduce the loss of the catalyst, and prolong the service life of the catalyst.

[0045] The second aspect of the present application provides a preparation method of the spherical alumina, which comprises the following steps:

[0046] (1) dissolving pseudoboehmite and boehmite to obtain an aluminum hydroxide slurry;

[0047] (2) dropping the aluminum hydroxide slurry into an oil-ammonia column to prepare wet aluminum hydroxide pellets, and then drying and calcining the wet aluminum hydroxide pellets;

[0048] wherein the crystal grain size of the boehmite meets: D (200) / D (002) = 0.5-1.5, D (200) / D (020) = 0.7-1.5, wherein D (020) , D (200) and D (002)The grain size calculated by Scherrer formula according to the half-peak width of diffraction peak along the (020) crystal face, (200) crystal face and (002) crystal face in the X-ray diffraction curve of the boehmite, respectively;

[0049] The D (120) is less than 10 nm, wherein the D (120) is the grain size calculated by Scherrer formula according to the half-peak width of diffraction peak along the (120) crystal face in the X-ray diffraction curve of the pseudoboehmite.

[0050] The dry mass content of the pseudoboehmite is 20-50% and the dry mass content of the boehmite is 50-80% based on the total mass of the pseudoboehmite and the boehmite.

[0051] The preparation method provided by the present application adopts the pseudoboehmite and the boehmite with specific grain sizes in specific proportions, and then the oil-ammonia column balling method is used to obtain the spherical alumina with suitable pore structure in the first aspect, which is used as a catalyst carrier and is beneficial to improving the catalytic performance of the catalyst. The catalyst prepared by using the spherical alumina as a carrier is used in the field of continuous reforming, which is beneficial to improving the aromatic yield.

[0052] In the present application, the specific definitions of the pseudoboehmite and the boehmite are well known to those skilled in the art, and will not be described in detail herein.

[0053] According to the present application, preferably, the grain size of the boehmite satisfies: D (200) / D (002) = 0.6-1.3, D (200) / D (020) = 0.8-1.5, wherein the D (020) , D (200) and D (002) are the grain sizes calculated by Scherrer formula according to the half-peak width of diffraction peak along the (020) crystal face, (200) crystal face and (002) crystal face in the X-ray diffraction curve of the boehmite. The boehmite with the above block structure is more beneficial to obtaining the spherical alumina with suitable pore structure in the present application.

[0054] According to the present application, preferably, the particle size of the boehmite is 0.1-500 μm, preferably 0.1-400 μm.

[0055] According to the present application, preferably, the D 5040-200 μm, preferably 40-100 μm, for example 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, and any value in the range between any two of these values.

[0056] Controlling the macro-particle size of the boehmite within the above range is advantageous for obtaining the spherical alumina of the pore structure according to the first aspect of the present application, while improving the pore volume of the spherical alumina.

[0057] According to the present application, preferably, the pseudo-boehmite has a D (120) less than 6 nm, for example 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, 5.5 nm, and any value in the range between any two of these values, wherein the D (120) is the grain size calculated from the half-peak width of the diffraction peak along the (120) crystal plane direction in the X-ray diffraction curve of the pseudo-boehmite. The use of the pseudo-boehmite with the above small grain size is advantageous for obtaining the spherical alumina of the pore structure according to the first aspect of the present application, while improving the strength of the spherical alumina.

[0058] According to the present application, preferably, the pseudo-boehmite has a particle size of 0.1-300 μm, preferably 0.5-200 μm.

[0059] According to the present application, preferably, the pseudo-boehmite has a D 50 5-60 μm, preferably 30-60 μm, for example 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, and any value in the range between any two of these values.

[0060] Controlling the macro-particle size of the pseudo-boehmite within the above range is advantageous for obtaining the spherical alumina of the pore structure according to the first aspect of the present application, while improving the strength of the spherical alumina.

[0061] The present application does not have a particular limitation on the source of the pseudo-boehmite and the boehmite, which can be commercially available or can be prepared by conventional methods in the art.

[0062] In the present application, the dry mass content of pseudoboehmite is 20-50%, preferably 20-40%, for example 20%, 25%, 30%, 35%, 40%, 45%, 50%, and any value in the range between any two of these values; the dry mass content of boehmite is 50-80%, preferably 60-80%, for example 50%, 55%, 60%, 65%, 70%, 75%, 80%, and any value in the range between any two of these values. Using pseudoboehmite and boehmite in a specific ratio is advantageous for forming spherical alumina with the special pore structure described in the first aspect.

[0063] The acid used in the peptization of step (1) can be selected from a wide range of acids, and can be selected according to conventional methods in the art. Preferably, the acid used in the peptization of step (1) is an inorganic acid and / or an organic acid, wherein the inorganic acid is nitric acid and / or hydrochloric acid, and the organic acid is selected from at least one of trichloroacetic acid, formic acid and citric acid.

[0064] According to the present application, preferably, the ratio of the mass of the acid used in the peptization of step (1) to the total mass of pseudoboehmite and boehmite in terms of alumina is 0.01-0.1, preferably 0.01-0.08.

[0065] According to the present application, preferably, the acid used in the peptization of step (1) is provided in the form of an acid solution, and the concentration of the acid solution is 0.1-2 mol / L, preferably 0.1-1.5 mol / L.

[0066] The peptization process of step (1) is not particularly limited, and can be performed according to conventional methods in the art. Preferably, the peptization of step (1) is performed for 0.5-20 h.

[0067] Preferably, the peptization of step (1) is performed under stirring.

[0068] The stirring rate is not particularly limited, and can be appropriately selected according to the specific conditions, with the proviso that the stirring is uniform. Preferably, the stirring rate is 60-300 rpm.

[0069] Preferably, water is further added during the peptization of step (1).

[0070] The amount of water used is not particularly limited, and can be appropriately selected according to the solid content of the aluminum hydroxide slurry, with the proviso that the solid content of the aluminum hydroxide slurry is in the following range.

[0071] According to the present application, preferably, the solid content of the aluminum hydroxide slurry obtained in step (1) is 15-28 wt%, preferably 15-25 wt%, more preferably 18-22 wt%.

[0072] According to the present application, preferably, the oil-ammonia column comprises an organic phase and an aqueous ammonia phase, and the height ratio of the organic phase to the aqueous ammonia phase is 1:5-300, preferably 1:5-200.

[0073] Preferably, the height of the aqueous ammonia phase is 100-300 cm.

[0074] The present application does not have special limitations on the specific type of the organic phase, which can be a conventional selection in the art. Preferably, the organic phase is C5-C 20 alkane, preferably at least one selected from the group consisting of gasoline, kerosene, petroleum ether, n-pentane, n-hexane, n-heptane, n-octane, n-decane and undecane.

[0075] According to the present application, preferably, the concentration of the aqueous ammonia is 6-18 wt%, preferably 5-15 wt%.

[0076] The present application does not have special limitations on the process of making wet aluminum hydroxide pellets, which can be carried out according to conventional methods in the art. Preferably, the process of making wet aluminum hydroxide pellets by dropping the aluminum hydroxide slurry into the ball-forming column in step (1) comprises: dropping the aluminum hydroxide slurry into the organic phase of the ball-forming column to form a ball, and then solidifying in the aqueous ammonia phase for 1-10 h to become a wet aluminum hydroxide pellet.

[0077] Specifically, the process of making wet aluminum hydroxide pellets by dropping the aluminum hydroxide slurry into the ball-forming column in step (2) comprises: dropping the aluminum hydroxide slurry into the upper layer of the oil-ammonia column with a droplet former, and due to the effect of surface tension, the droplet shrinks into a spherical shape when passing through the upper layer of the organic phase, and then passes through the interface between the oil phase and the aqueous ammonia phase to gel in the aqueous ammonia. The gelled particles are solidified in the lower layer of the aqueous ammonia phase of the oil-ammonia column for 1-10 h to become wet aluminum hydroxide pellets (i.e. gel pellets in the examples), which are collected at the bottom of the oil-ammonia column.

[0078] The present application does not have special limitations on the drying in step (2), which can be carried out according to conventional methods in the art. Preferably, the drying conditions in step (2) comprise: a temperature of 50-150℃ and a time of 5-24 hours.

[0079] Further preferably, the drying conditions in step (2) comprise: first drying at 50-80℃ for 2-8 hours, and then drying at 90-150℃ for 6-12 hours.

[0080] According to the present application, preferably, the calcination conditions in step (2) comprise: a temperature of 450-800℃ and a time of 2-8 hours.

[0081] The third aspect of the present application provides the use of the spherical alumina of the first aspect or the spherical alumina prepared by the method of the second aspect in the preparation of a catalyst, preferably in the preparation of a continuous reforming catalyst.

[0082] The spherical alumina provided by the present application is suitable for use as a catalyst carrier, preferably as a carrier for a continuous reforming catalyst.

[0083] Preferably, the active component of the continuous reforming catalyst is selected from noble metals and / or Group VIII metals.

[0084] The present application will be described in detail below by way of examples.

[0085] In the following examples, the test methods for the pore size distribution, specific surface area, pore volume, sphericity, crushing strength and average particle size of the spherical alumina are as given above;

[0086] The test method for the grain size of boehmite and pseudoboehmite is as follows: the XRD diffraction curve is measured by a Philips X'pert X-ray diffractometer using a Cu target, Kα radiation, Ni filter, λ = 0.154056 nm. Solid detector, tube voltage 40 kV, tube current 40 mA, scanning range 5°-90°, and then calculated according to the Scherrer formula: D = Kλ / (Bcosθ) (D is the grain size, λ is the diffraction wavelength of the target material, B is the corrected half-peak width of the diffraction peak, and 2θ is the position of the diffraction peak);

[0087] The particle size distribution of pseudoboehmite and boehmite is measured by a BetterSize 2000 laser scattering instrument of Dandong Better Technology Co., Ltd. The measurement method is as follows: set the particle refractive index to 1.530; the particle absorption rate to 0.1; the dispersant to water; the dispersant refractive index to 1.330; the instrument range to 20 nm-2 mm. Click automatic calibration, after the instrument is calibrated, add the sample to be measured into the sample tank, stop adding when the concentration reaches the measurement requirement, and the instrument automatically detects; after the detection is completed, record the measured particle size distribution and D 50 value.

[0088] Example 1

[0089] (1) Preparation of pseudoboehmite and boehmite

[0090] In a three-necked flask with a reflux condenser, 54 grams of aluminum chips with a purity of 99.95 wt% were added, and 180 mL (1.4 mol) of n-hexanol with a purity of 99.8 wt% was added. The reaction was started after refluxing at 130°C for 20 min, and 724 mL (5.8 mol) of n-hexanol was slowly added to the three-necked flask. The temperature was maintained at 140°C, and the reaction was refluxed for 2 h to obtain a mixture of n-hexoxy aluminum and n-hexanol.

[0091] A mixture of n-hexyloxyaluminum and n-hexanol was cooled to 90°C, and 936 g of deionized water was added thereto at a stirring speed of 120 rpm to hydrolyze for 30 min, to obtain a two-phase system of n-hexanol phase as the upper layer and aluminum hydroxide slurry phase as the lower layer. The n-hexanol phase of the upper layer was separated by decantation to obtain the aluminum hydroxide slurry without alcohol. The aluminum hydroxide slurry was directly spray-dried at 180°C to obtain a boehmite powder. The characteristic parameters thereof are shown in Table 1.

[0092] The aluminum hydroxide slurry was prepared by the same method as described above, and a crystal grain structure regulator composed of 12 g of 2-hydroxypropionic acid and 28 g of n-hexanol was added thereto. After stirring, the aluminum hydroxide slurry was transferred to a stainless steel autoclave with an adjustable speed mechanical stirrer, and was aged at 120°C for 6 h at a stirring speed of 200 rpm. After aging, the slurry was washed with deionized water, and then was dried in an oven at 120°C for 12 h. The dried product was ground to obtain an alumina hydrate powder. The characteristic parameters thereof are shown in Table 1.

[0093] (2) Preparation of an aluminum hydroxide sol

[0094] 30 g (dry basis of aluminum oxide) of the boehmite powder prepared above and 70 g (dry basis of aluminum oxide) of the alumina hydrate powder were taken, and were peptized by adding a 0.19 mol / L nitric acid solution having a volume of 265 mL, and then deionized water was added to a total mass of 396 g. The peptized product was dispersed for 3 h at a stirring speed of 300 r / min to obtain an aluminum hydroxide sol having a solid content of 20 wt%.

[0095] (3) Preparation of alumina pellets

[0096] The aluminum hydroxide sol prepared in step (2) was dropped into an oil-ammonia column by a dropping device. The oil-ammonia column had an upper oil phase and a lower aqueous ammonia phase. The upper oil phase was n-decane having a height of 1 cm, and the lower aqueous ammonia phase was aqueous ammonia having a concentration of 8 wt% and a height of 150 cm. The aluminum hydroxide sol dropped into the oil phase was shrunken into a spherical shape under the action of surface tension, passed through the interface between the oil phase and the aqueous ammonia phase, and was gelled in the aqueous ammonia. The gelled particles were further solidified in the lower aqueous ammonia phase of the oil-ammonia column for 2 h to form gel pellets, which were collected at the bottom of the oil-ammonia column. The gel pellets were taken out from the bottom of the oil-ammonia column, dried at 60°C for 3 h, at 120°C for 9 h, and then calcined at 600°C for 6 h to obtain γ-Al2O3 pellets A, which had a pelletization yield of 97.8 wt%.

[0097] The pore diameter distribution of the γ-Al2O3 pellets A is shown in Table 2, and the crushing strength and other physicochemical properties thereof are shown in Table 3.

[0098] Example 2

[0099] (1) Preparation of pseudoboehmite and boehmite

[0100] In a three-necked flask with reflux condenser, 54 g of aluminum chips with purity of 99.95 wt% were added, and 180 mL (1.4 mol) of n-hexanol with purity of 99.8 wt% was added. The reaction was started after refluxing at 130°C for 20 min, and 724 mL (5.8 mol) of n-hexanol was slowly added to the three-necked flask. The temperature was maintained at 140°C, and the reaction was refluxed for 2 h to obtain a mixture of aluminum n-hexoxide and n-hexanol.

[0101] The mixture of aluminum n-hexoxide and n-hexanol was cooled to 90°C, and 936 g of deionized water was added to the mixture under stirring at a speed of 120 rpm for hydrolysis. The hydrolysis time was 30 min to obtain a two-phase system with n-hexanol phase on the top and aluminum hydroxide slurry phase on the bottom. The n-hexanol phase on the top was separated by decantation to obtain aluminum hydroxide slurry without alcohol. The aluminum hydroxide slurry was directly spray-dried at 180°C to obtain pseudoboehmite powder. The characteristic parameters are shown in Table 1.

[0102] The aluminum hydroxide slurry was prepared by the same method as described above. The crystal grain structure regulator composed of 12 g of 2-hydroxypropionic acid and 28 g of n-hexanol was added to the aluminum hydroxide slurry, which was stirred uniformly. Then, the aluminum hydroxide slurry was transferred to a stainless steel autoclave with adjustable speed mechanical stirring. The slurry was aged at 120°C for 6 h under stirring at a speed of 200 rpm. After aging, the slurry was washed with deionized water, and then dried in an oven at 120°C for 12 h. The boehmite powder was obtained by grinding. The characteristic parameters are shown in Table 1.

[0103] (2) Preparation of aluminum hydroxide sol

[0104] The pseudoboehmite powder prepared above was taken as 20 g (dry basis of aluminum oxide), and the boehmite powder was taken as 80 g (dry basis of aluminum oxide). The two powders were added to 267 mL of nitric acid solution with a concentration of 0.19 mol / L for peptization. Then, deionized water was added to a total mass of 399 g. The peptization was dispersed under stirring at a speed of 100 r / min for 6 h to obtain an aluminum hydroxide sol with a solid content of 20 wt%.

[0105] (3) Preparation of aluminum oxide pellets

[0106] The aluminum hydroxide sol prepared in step (2) was dropped into an oil-ammonia column with a dropping device. The upper layer of the oil-ammonia column was an oil phase, and the lower layer was an ammonia water phase. The upper layer of the oil phase was n-octane with a height of 2 cm, and the lower layer of the ammonia water phase was ammonia water with a concentration of 8% by weight and a height of 200 cm. The aluminum hydroxide sol was dropped into the oil layer, and under the action of surface tension, it was contracted into a spherical shape, passed through the interface between the oil phase and the ammonia water phase, and was gelled in the ammonia water. The gelled particles were further solidified in the ammonia water phase of the lower layer of the oil-ammonia column for 2 hours to form gel beads, and the gel beads were collected at the bottom of the oil-ammonia column. The obtained gel beads were taken out from the bottom of the oil-ammonia column, dried at 60°C for 3 hours, dried at 120°C for 9 hours, and then calcined at 600°C for 6 hours to obtain γ-Al2O3 beads B, and the yield of the beads was 97% by weight.

[0107] The pore diameter distribution of the γ-Al2O3 beads B is shown in Table 2, and the crushing strength and other physicochemical properties are shown in Table 3.

[0108] Example 3

[0109] (1) Preparation of pseudoboehmite and boehmite

[0110] In a three-necked flask with a reflux condenser, 54 g of aluminum chips with a purity of 99.95% by weight were added, and 180 mL (1.4 mol) of n-hexanol with a purity of 99.8% by weight was added. The reaction was started after refluxing at 130°C for 20 min, and 724 mL (5.8 mol) of n-hexanol was slowly added to the three-necked flask. The temperature was maintained at 140°C, and the reaction was continued for 2 hr to obtain a mixture of aluminum hexyloxide and n-hexanol.

[0111] The mixture of aluminum hexyloxide and n-hexanol was cooled to 90°C, and 936 g of deionized water was added thereto under stirring at a speed of 120 rpm for hydrolysis. The hydrolysis time was 30 min to obtain a two-phase system with the upper layer being the n-hexanol phase and the lower layer being the aluminum hydroxide slurry phase. The n-hexanol phase in the upper layer was separated by decantation to obtain the aluminum hydroxide slurry without alcohol. The aluminum hydroxide slurry was directly spray-dried at 180°C to obtain pseudoboehmite powder. The characteristic parameters are shown in Table 1.

[0112] The aluminum hydroxide slurry was prepared by the same method as described above, and 6 g of 2-hydroxypropionic acid and 14 g of n-hexanol were added to the aluminum hydroxide slurry to form a crystal grain structure regulator. After stirring, the aluminum hydroxide slurry was transferred to a stainless steel pressure vessel with an adjustable speed mechanical stirrer. The slurry was aged at 120°C for 10 h under stirring at a speed of 200 rpm. After aging, the slurry was washed with deionized water, and then was dried in an oven at 120°C for 12 h. The boehmite powder was obtained after grinding. The characteristic parameters are shown in Table 1.

[0113] (2) Preparation of aluminum hydroxide sol

[0114] Take 40 g (alumina dry basis mass) of the pseudo-boehmite powder prepared above and 60 g (alumina dry basis mass) of boehmite powder, add 263 ml of nitric acid solution with a concentration of 0.19 mol / L for peptization, then add deionized water to a total mass of 393 g, disperse and peptize at a stirring rate of 300 r / min for 1 h, and obtain an aluminum hydroxide sol with a solid content of 20 wt%.

[0115] (3) Preparation of alumina pellets

[0116] The aluminum hydroxide sol prepared in step (2) is dropped into an oil-ammonia column using a dropping device, the upper layer of the oil-ammonia column is an oil phase, and the lower layer is an ammonia water phase, the upper layer of the oil phase is n-octane with a height of 1 cm, and the lower layer of the ammonia water phase is ammonia water with a concentration of 8 wt% and a height of 200 cm; the aluminum hydroxide sol is dropped into the oil layer, shrinks into a spherical shape under the action of surface tension, passes through the interface between the oil phase and the ammonia water phase, and is gelled in the ammonia water. The gelled particles continue to solidify in the ammonia water phase at the lower layer of the oil-ammonia column for 2 h to form gel pellets, and the gel pellets are collected at the bottom of the oil-ammonia column. The obtained gel pellets are taken out from the bottom of the oil-ammonia column, dried at 60°C for 3 h, dried at 120°C for 9 h, and then calcined at 600°C for 6 h to obtain γ-Al2O3 pellets C, with a pellet yield of 97.5 wt%.

[0117] The pore diameter distribution of the γ-Al2O3 pellets C is shown in Table 2, and the crushing strength and other physicochemical properties are shown in Table 3.

[0118] Example 4

[0119] (1) Preparation of pseudo-boehmite and boehmite

[0120] In a three-necked flask with a reflux condenser, 54 g of aluminum chips with a purity of 99.95 wt% are added, and 180 mL (1.4 mol) of n-hexanol with a purity of 99.8 wt% is added at the same time. The reaction is started after refluxing at 130°C for 20 min, and 724 mL (5.8 mol) of n-hexanol is slowly added to the three-necked flask while maintaining the temperature at 140°C. The reaction is continued for 2 h to obtain a mixture of aluminum n-hexoxide and n-hexanol.

[0121] The mixture of aluminum n-hexoxide and n-hexanol is cooled to 80°C, and 936 g of deionized water is added to it at a stirring speed of 120 rpm for hydrolysis. The hydrolysis time is 10 min, and a two-phase system with the upper layer being the n-hexanol phase and the lower layer being the aluminum hydroxide slurry phase is obtained. The n-hexanol phase in the upper layer is separated by decantation to obtain an alcohol-free aluminum hydroxide slurry. The aluminum hydroxide slurry is directly spray dried at 200°C to obtain a pseudo-boehmite powder. The characteristic parameters are shown in Table 1.

[0122] The same method as described above was used to prepare the aluminum hydroxide slurry, and 6 g of 2-hydroxypropionic acid and 14 g of n-hexanol were added to the aluminum hydroxide slurry as a crystal grain structure regulator. After stirring, the aluminum hydroxide slurry was transferred to a stainless steel autoclave with adjustable speed mechanical stirring, and was aged at 120°C and a stirring speed of 200 rpm for 10 h. After aging, the slurry was washed with deionized water, and then was dried in an oven at 120°C for 12 h. The boehmite powder was obtained after grinding. The characteristic parameters are shown in Table 1.

[0123] (2) Preparation of aluminum hydroxide sol

[0124] The pseudo-boehmite powder prepared above and 75 g (alumina dry basis mass) of boehmite powder were taken, and 266 mL of a 0.19 mol / L nitric acid solution was added for peptization. Then deionized water was added to a total mass of 397.5 g, and the mixture was dispersed and peptized at a stirring speed of 300 r / min for 3 h to obtain an aluminum hydroxide sol with a solid content of 20 wt%.

[0125] (3) Preparation of alumina pellets

[0126] The aluminum hydroxide sol prepared in step (2) was dropped into an oil-ammonia column using a dropping device. The upper layer of the oil-ammonia column was an oil phase, and the lower layer was an aqueous ammonia phase. The upper oil phase was n-decane with a height of 1 cm, and the lower aqueous ammonia phase was aqueous ammonia with a concentration of 8 wt% and a height of 300 cm. The aluminum hydroxide sol was dropped into the oil layer, and under the action of surface tension, the sol shrank into spherical shape, passed through the interface between the oil phase and the aqueous ammonia phase, and was gelled in the aqueous ammonia. The gelled particles were further solidified in the aqueous ammonia phase of the lower layer of the oil-ammonia column for 6 h to form gel pellets, which were collected at the bottom of the oil-ammonia column. The obtained gel pellets were taken out from the bottom of the oil-ammonia column, dried at 60°C for 3 h, at 120°C for 9 h, and then calcined at 600°C for 6 h to obtain γ-Al2O3 pellets D, with a pellet yield of 97.8 wt%.

[0127] The pore diameter distribution of the γ-Al2O3 pellets D is shown in Table 1, and other physicochemical properties and crushing strength are shown in Table 2.

[0128] Example 5

[0129] (1) Preparation of pseudo-boehmite and boehmite

[0130] In a three-necked flask with a reflux condenser, 54 g of aluminum chips with a purity of 99.95 wt% were added, and 180 mL (1.4 mol) of n-hexanol with a purity of 99.8 wt% was added. The reaction was started after refluxing at 130°C for 20 min, and 724 mL (5.8 mol) of n-hexanol was slowly added to the three-necked flask. The temperature was maintained at 140°C, and the reaction was continued for 2 h to obtain a mixture of aluminum n-hexoxide and n-hexanol.

[0131] A mixture of aluminum n-hexylate and n-hexanol was cooled to 80°C, and 936 g of deionized water was added thereto under stirring at a speed of 120 rpm to hydrolyze the mixture for 10 min, to obtain a two-phase system of an upper n-hexanol phase and a lower aluminum hydroxide slurry phase. The n-hexanol phase was separated by decantation to obtain an aluminum hydroxide slurry free of alcohol. The aluminum hydroxide slurry was directly spray-dried at 200°C to obtain a pseudoboehmite powder. The characteristic parameters of the powder are shown in Table 1.

[0132] An aluminum hydroxide slurry was prepared by the same method as described above, and a crystal grain structure regulator composed of 8 g of 2-hydroxypropionic acid and 28 g of n-hexanol was added to the aluminum hydroxide slurry. After stirring, the aluminum hydroxide slurry was transferred to a stainless steel autoclave with an adjustable speed mechanical stirrer, and was aged at 120°C for 8 h under stirring at a speed of 200 rpm. After aging, the slurry was washed with deionized water, and then was dried in an oven at 120°C for 12 h. The dried slurry was ground to obtain a boehmite powder. The characteristic parameters of the boehmite powder are shown in Table 1.

[0133] (2) Preparation of an aluminum hydroxide sol

[0134] An aluminum hydroxide sol was prepared by adding 264 ml of a 0.19 mol / L nitric acid solution to 35 g (dry basis) of the pseudoboehmite powder prepared in the above step (1) and 65 g (dry basis) of the boehmite powder, and then adding deionized water to a total mass of 394.5 g, and dispersing and peptizing the mixture for 3 h under stirring at a speed of 300 r / min, to obtain an aluminum hydroxide sol having a solid content of 20 wt%.

[0135] (3) Preparation of an aluminum oxide pellet

[0136] The aluminum hydroxide sol prepared in step (2) was dropped into an oil-ammonia column by a dropping device. The oil-ammonia column had an upper oil phase and a lower aqueous ammonia phase. The upper oil phase was n-decane having a height of 2 cm, and the lower aqueous ammonia phase was aqueous ammonia having a concentration of 8 wt% and a height of 150 cm. The aluminum hydroxide sol dropped into the oil phase was shrunken into a spherical shape under the action of surface tension, passed through the interface between the oil phase and the aqueous ammonia phase, and was gelled in the aqueous ammonia. The gelled particles were further solidified in the aqueous ammonia phase for 4 h to form gel pellets, which were collected at the bottom of the oil-ammonia column. The gel pellets were taken out from the bottom of the oil-ammonia column, dried at 60°C for 3 h, at 120°C for 9 h, and then calcined at 600°C for 6 h to obtain γ-Al2O3 pellets E, which had a pellet yield of 97.8 wt%.

[0137] The pore diameter distribution of the γ-Al2O3 pellets E is shown in Table 2, and the crushing strength and other physical and chemical properties are shown in Table 3.

[0138] Example 6

[0139] (1) Preparation of pseudoboehmite and boehmite

[0140] In a three-necked flask with reflux condenser, 54 g of aluminum chips with purity of 99.95% by weight were added, and 180 mL (1.4 mol) of n-hexanol with purity of 99.8% by weight was added. The reaction was started after 20 min of reflux at 130°C, and 724 mL (5.8 mol) of n-hexanol was slowly added to the three-necked flask. The temperature was maintained at 140°C, and the reaction was continued for 2 h of reflux to obtain a mixture of aluminum n-hexoxide and n-hexanol.

[0141] The mixture of aluminum n-hexoxide and n-hexanol was cooled to 90°C, and 936 g of deionized water was added to the mixture under stirring at a speed of 120 rpm for 30 min of hydrolysis to obtain a two-phase system with the upper layer being the n-hexanol phase and the lower layer being the aluminum hydroxide slurry phase. The n-hexanol phase was separated by decantation to obtain the aluminum hydroxide slurry without alcohol. The aluminum hydroxide slurry was directly spray-dried at 180°C to obtain the pseudoboehmite powder. The characteristic parameters are shown in Table 1.

[0142] The aluminum hydroxide slurry was prepared by the same method as described above, and 16 g of malic acid and 20 g of isopropyl alcohol were added to the aluminum hydroxide slurry as the crystal grain structure regulator. After stirring, the aluminum hydroxide slurry was transferred to a stainless steel autoclave with adjustable speed mechanical stirring, and was aged at 120°C for 6 h under stirring at a speed of 200 rpm. After aging, the slurry was washed with deionized water, and was dried in an oven at 120°C for 12 h. The dried slurry was ground to obtain the boehmite powder. The characteristic parameters are shown in Table 1.

[0143] (2) Preparation of aluminum hydroxide sol

[0144] 30 g (dry basis of aluminum oxide) of the pseudoboehmite powder prepared above and 70 g (dry basis of aluminum oxide) of the boehmite powder were taken, and 261 mL of a nitric acid solution with a concentration of 0.19 mol / L was added for peptization. Then, deionized water was added to a total mass of 391 g, and the mixture was dispersed and peptized for 3 h under stirring at a speed of 300 r / min to obtain an aluminum hydroxide sol with a solid content of 20% by weight.

[0145] (3) Preparation of aluminum oxide pellets

[0146] The aluminum hydroxide sol prepared in step (2) was dropped into an oil-ammonia column by a dropping device. The upper layer of the oil-ammonia column was an oil phase, and the lower layer was an ammonia water phase. The upper layer of the oil phase was n-decane with a height of 1 cm, and the lower layer of the ammonia water phase was ammonia water with a concentration of 8% by weight and a height of 150 cm. The aluminum hydroxide sol was dropped into the oil layer, and under the action of surface tension, it was contracted into a spherical shape, passed through the interface between the oil phase and the ammonia water phase, and was gelled in the ammonia water. The gelled particles were further solidified in the ammonia water phase of the lower layer of the oil-ammonia column for 2 h to form gel beads, and the gel beads were collected at the bottom of the oil-ammonia column. The obtained gel beads were taken out from the bottom of the oil-ammonia column, dried at 60°C for 3 h, dried at 120°C for 9 h, and then calcined at 550°C for 6 h to obtain γ-Al2O3 beads F, and the yield of the beads was 96.9% by weight.

[0147] The pore diameter distribution of the γ-Al2O3 beads F is shown in Table 2, and the crushing strength and other physicochemical properties are shown in Table 3.

[0148] Example 7

[0149] (1) Preparation of pseudoboehmite and boehmite

[0150] In a three-necked flask with a reflux condenser, 54 g of aluminum chips with a purity of 99.95% by weight were added, and 180 mL (1.4 mol) of n-hexanol with a purity of 99.8% by weight was added. The reaction was started after refluxing at 130°C for 20 min, and 724 mL (5.8 mol) of n-hexanol was slowly added to the three-necked flask. The temperature was maintained at 140°C, and the reaction was refluxed for 2 h to obtain a mixture of aluminum n-hexoxide and n-hexanol.

[0151] The mixture of aluminum n-hexoxide and n-hexanol was cooled to 90°C, and 936 g of deionized water was added thereto under stirring at a speed of 120 rpm for hydrolysis. The hydrolysis time was 30 min to obtain a two-phase system with the upper layer being the n-hexanol phase and the lower layer being the aluminum hydroxide slurry phase. The n-hexanol phase in the upper layer was separated by decantation to obtain the aluminum hydroxide slurry without alcohol. The aluminum hydroxide slurry was directly spray dried at 180°C to obtain pseudoboehmite powder. The characteristic parameters are shown in Table 1.

[0152] The aluminum hydroxide slurry was prepared by the same method as described above, and a crystal grain structure regulator composed of 16 g of malic acid and 20 g of isopropyl alcohol was added to the aluminum hydroxide slurry. After stirring uniformly, the aluminum hydroxide slurry was transferred to a stainless steel pressure tank with an adjustable speed mechanical stirrer. The slurry was aged at 120°C for 8 h under stirring at a speed of 200 rpm. After aging, the slurry was washed with deionized water, and then was dried in an oven at 120°C for 12 h. The boehmite powder was obtained after grinding. The characteristic parameters are shown in Table 1.

[0153] (2) Preparation of aluminum hydroxide sol

[0154] Take 35 g (alumina dry basis mass) of the pseudo-boehmite powder prepared above and 65 g (alumina dry basis mass) of boehmite powder, add 259 ml of nitric acid solution with a concentration of 0.19 mol / L for peptization, then add deionized water to a total mass of 388 g, disperse and peptize for 3 hours at a stirring rate of 200 r / min, and obtain an aluminum hydroxide sol with a solid content of 20 wt%.

[0155] (3) Preparation of alumina pellets

[0156] The aluminum hydroxide sol prepared in step (2) is dropped into an oil-ammonia column using a dropping device, the upper layer of the oil-ammonia column is an oil phase, and the lower layer is an ammonia water phase, the upper layer of the oil phase is n-decane with a height of 2 cm, and the lower layer of the ammonia water phase is ammonia water with a concentration of 8 wt% and a height of 150 cm; the aluminum hydroxide sol is dropped into the oil layer, shrinks into a spherical shape under the action of surface tension, passes through the interface between the oil phase and the ammonia water phase, and is gelled in the ammonia water. The gelled particles continue to solidify in the ammonia water phase at the lower layer of the oil-ammonia column for 2 hours to form gel pellets, and the gel pellets are collected at the bottom of the oil-ammonia column. The obtained gel pellets are taken out from the bottom of the oil-ammonia column, dried at 60°C for 3 hours, dried at 120°C for 9 hours, and then calcined at 550°C for 6 hours to obtain γ-Al2O3 pellets G, with a pellet yield of 97.7 wt%.

[0157] The pore diameter distribution of the γ-Al2O3 pellets G is shown in Table 2, and the crushing strength and other physicochemical properties are shown in Table 3.

[0158] Example 8

[0159] (1) Preparation of pseudo-boehmite and boehmite

[0160] In a three-necked flask with a reflux condenser, 54 g of aluminum chips with a purity of 99.95 wt% are added, and 180 mL (1.4 mol) of n-hexanol with a purity of 99.8 wt% is added at the same time. The reaction is started after refluxing at 130°C for 20 min, and 724 mL (5.8 mol) of n-hexanol is slowly added to the three-necked flask while maintaining the temperature at 140°C. The reaction is continued for 2 h to obtain a mixture of aluminum n-hexoxide and n-hexanol.

[0161] The mixture of aluminum n-hexoxide and n-hexanol is cooled to 80°C, and 936 g of deionized water is added to it at a stirring speed of 120 rpm for hydrolysis. The hydrolysis time is 10 min, and a two-phase system with the upper layer being the n-hexanol phase and the lower layer being the aluminum hydroxide slurry phase is obtained. The n-hexanol phase in the upper layer is separated by decantation to obtain an aluminum hydroxide slurry without alcohol. The aluminum hydroxide slurry is directly spray dried at 200°C to obtain a pseudo-boehmite powder. The characteristic parameters are shown in Table 1.

[0162] The same method as described above was used to prepare the aluminum hydroxide slurry, and 12 g of malic acid and 20 g of isopropyl alcohol were added to the aluminum hydroxide slurry as a crystal grain structure regulator. After stirring, the aluminum hydroxide slurry was transferred to a stainless steel autoclave with adjustable speed mechanical stirring, and was aged at 120°C and a stirring speed of 200 rpm for 10 h. After aging, the slurry was washed with deionized water, then dried in an oven at 120°C for 12 h, and then ground to obtain boehmite powder. The characteristic parameters are shown in Table 1.

[0163] (2) Preparation of aluminum hydroxide sol

[0164] The same method as described above was used to prepare the aluminum hydroxide slurry, and 12 g of malic acid and 20 g of isopropyl alcohol were added to the aluminum hydroxide slurry as a crystal grain structure regulator. After stirring, the aluminum hydroxide slurry was transferred to a stainless steel autoclave with adjustable speed mechanical stirring, and was aged at 120°C and a stirring speed of 200 rpm for 10 h. After aging, the slurry was washed with deionized water, then dried in an oven at 120°C for 12 h, and then ground to obtain boehmite powder. The characteristic parameters are shown in Table 1.

[0165] (3) Preparation of aluminum oxide pellets

[0166] The aluminum hydroxide sol prepared in step (2) was dropped into an oil-ammonia column using a dropping device. The upper layer of the oil-ammonia column was an oil phase, and the lower layer was an aqueous ammonia phase. The upper layer of oil was n-octane with a height of 4 cm, and the lower layer of aqueous ammonia was aqueous ammonia with a concentration of 8 wt% and a height of 200 cm. The aluminum hydroxide sol was dropped into the oil layer, and under the action of surface tension, the sol shrank into spherical shape, passed through the interface between the oil phase and the aqueous ammonia phase, and gelled in the aqueous ammonia. The gelled particles were further solidified in the aqueous ammonia phase of the lower layer of the oil-ammonia column for 2 h to form gel pellets, which were collected at the bottom of the oil-ammonia column. The obtained gel pellets were taken out from the bottom of the oil-ammonia column, dried at 60°C for 3 h, at 120°C for 9 h, and then calcined at 550°C for 6 h to obtain γ-Al2O3 pellets H, with a pellet yield of 96.6 wt%.

[0167] The pore diameter distribution of the γ-Al2O3 pellets H is shown in Table 2, and the crushing strength and other physicochemical properties are shown in Table 3.

[0168] Example 9

[0169] (1) Preparation of pseudoboehmite and boehmite

[0170] In a three-necked flask with a reflux condenser, 54 g of aluminum chips with a purity of 99.95 wt% were added, and 180 mL (1.4 mol) of n-hexanol with a purity of 99.8 wt% was added. The reaction was started after refluxing at 130°C for 20 min, and 724 mL (5.8 mol) of n-hexanol was slowly added to the three-necked flask while maintaining the temperature at 140°C. The reaction was continued for 2 h to obtain a mixture of aluminum n-hexoxide and n-hexanol.

[0171] A mixture of aluminum n-hexoxide and n-hexanol was cooled to 90°C, and 936 g of deionized water was added thereto under stirring at a speed of 120 rpm to hydrolyze the mixture for 30 min, to obtain a two-phase system of n-hexanol phase on the top and aluminum hydroxide slurry phase on the bottom. The n-hexanol phase on the top was separated by decantation to obtain the aluminum hydroxide slurry without alcohol. The aluminum hydroxide slurry was directly spray-dried at 180°C to obtain a boehmite powder. The characteristic parameters of the boehmite powder are shown in Table 1.

[0172] The aluminum hydroxide slurry was prepared by the same method as described above, and 12 g of malic acid and 20 g of isopropyl alcohol were added to the aluminum hydroxide slurry as a crystal grain structure regulator. After stirring, the aluminum hydroxide slurry was transferred to a stainless steel autoclave with adjustable speed mechanical stirring, and was aged at 120°C for 10 h with a stirring speed of 200 rpm. After aging, the slurry was washed with deionized water, and then was dried in an oven at 120°C for 12 h. The dried slurry was ground to obtain a boehmite powder. The characteristic parameters of the boehmite powder are shown in Table 1.

[0173] (2) Preparation of aluminum hydroxide sol

[0174] Forty grams (dry basis of aluminum oxide) of the boehmite powder prepared above and 60 g (dry basis of aluminum oxide) of the boehmite powder were added to 259 ml of a 0.19 mol / L nitric acid solution for peptization, and then deionized water was added to a total mass of 387 g. The mixture was dispersed and peptized for 3 h at a stirring speed of 300 r / min to obtain an aluminum hydroxide sol with a solid content of 20 wt%.

[0175] (3) Preparation of aluminum oxide pellets

[0176] The aluminum hydroxide sol prepared in step (2) was dropped into an oil-ammonia column by a dropping device. The upper layer of the oil-ammonia column was an oil phase, and the lower layer was an ammonia water phase. The upper oil phase was n-decane with a height of 4 cm, and the lower ammonia water phase was ammonia water with a concentration of 8 wt% and a height of 300 cm. The aluminum hydroxide sol was dropped into the oil layer, and was contracted into spherical shape under the action of surface tension, and then passed through the interface of the oil phase and the ammonia water phase to be gelled in the ammonia water. The gelled particles were further solidified in the ammonia water phase of the lower layer of the oil-ammonia column for 2 h to form gel pellets, which were collected at the bottom of the oil-ammonia column. The obtained gel pellets were taken out from the bottom of the oil-ammonia column, and were dried at 60°C for 3 h, at 120°C for 9 h, and then were calcined at 550°C for 6 h to obtain γ-Al2O3 pellets I, with a pellet yield of 98.3 wt%.

[0177] The pore diameter distribution of the γ-Al2O3 pellets I is shown in Table 2, and the crushing strength and other physicochemical properties are shown in Table 3.

[0178] Example 10

[0179] (1) Preparation of boehmite and boehmite

[0180] In a three-necked flask with reflux condenser, 54 g of aluminum chips with purity of 99.95% by weight were added, and 180 mL (1.4 mol) of n-hexanol with purity of 99.8% by weight was added. The reaction was started after 20 min of reflux at 130°C, and 724 mL (5.8 mol) of n-hexanol was slowly added to the three-necked flask. The temperature was maintained at 140°C, and the reaction was continued for 2 h of reflux to obtain a mixture of aluminum n-hexoxide and n-hexanol.

[0181] The mixture of aluminum n-hexoxide and n-hexanol was cooled to 90°C, and 936 g of deionized water was added to the mixture under stirring at a speed of 120 rpm for 30 min of hydrolysis to obtain a two-phase system with the upper layer being the n-hexanol phase and the lower layer being the aluminum hydroxide slurry phase. The n-hexanol phase was separated by decantation to obtain the aluminum hydroxide slurry without alcohol. The aluminum hydroxide slurry was directly spray-dried at 180°C to obtain the pseudoboehmite powder. The characteristic parameters are shown in Table 1.

[0182] The aluminum hydroxide slurry was prepared by the same method as described above, and 8 g of malic acid and 20 g of isopropyl alcohol were added to the aluminum hydroxide slurry as the crystal grain structure regulator. After stirring, the aluminum hydroxide slurry was transferred to a stainless steel autoclave with adjustable speed mechanical stirring, and was aged at 120°C for 12 h under stirring at a speed of 200 rpm. After aging, the slurry was washed with deionized water, and was dried in an oven at 120°C for 12 h. The dried slurry was ground to obtain the boehmite powder. The characteristic parameters are shown in Table 1.

[0183] (2) Preparation of aluminum hydroxide sol

[0184] 25 g (dry basis of aluminum oxide) of the pseudoboehmite powder prepared above and 75 g (dry basis of aluminum oxide) of the boehmite powder were taken, and 261 mL of a nitric acid solution with a concentration of 0.19 mol / L was added for peptization. Then, deionized water was added to a total mass of 390 g, and the mixture was dispersed and peptized for 3 h under stirring at a speed of 300 r / min to obtain an aluminum hydroxide sol with a solid content of 20% by weight.

[0185] (3) Preparation of aluminum oxide pellets

[0186] The aluminum hydroxide sol prepared in step (2) was dropped into the oil-ammonia column by a dropping device. The upper layer of the oil-ammonia column was an oil phase, and the lower layer was an ammonia water phase. The upper oil phase was n-decane with a height of 10 cm, and the lower ammonia water phase was ammonia water with a concentration of 8% by weight and a height of 150 cm. The aluminum hydroxide sol was dropped into the oil layer, and under the action of surface tension, it was contracted into spherical shape, passed through the interface between the oil phase and the ammonia water phase, and was gelled in the ammonia water. The gelled particles were further solidified in the ammonia water phase of the lower layer of the oil-ammonia column for 6 hours to form gel beads, which were collected at the bottom of the oil-ammonia column. The obtained gel beads were taken out from the bottom of the oil-ammonia column, dried at 60°C for 3 hours, at 120°C for 9 hours, and then calcined at 550°C for 6 hours to obtain γ-Al2O3 beads J, with a bead yield of 97.2% by weight.

[0187] The pore diameter distribution of the γ-Al2O3 beads J is shown in Table 2, and the crushing strength and other physicochemical properties are shown in Table 3.

[0188] Comparative Example 1

[0189] The method of Example 1 was followed, except that in the preparation of the aluminum hydroxide sol, no boehmite was added, and only pseudo-boehmite was used as the raw material. Specifically, 100 g (alumina dry basis mass) of pseudo-boehmite was added to 251 ml of a nitric acid solution with a concentration of 0.19 mol / L for peptization, and then deionized water was added to a total mass of 375 g to obtain an aluminum hydroxide sol with an alumina content of 20% by weight. Finally, γ-Al2O3 beads K were obtained, with a bead yield of 98.9% by weight.

[0190] The pore diameter distribution of the γ-Al2O3 beads K is shown in Table 2, and the crushing strength and other physicochemical properties are shown in Table 3.

[0191] Comparative Example 2

[0192] The method of Example 1 was followed, except that in the preparation of the aluminum hydroxide sol, the mass of pseudo-boehmite was 10 g (alumina dry basis mass), and the mass of boehmite was 90 g (alumina dry basis mass). A 269 ml nitric acid solution with a concentration of 0.19 mol / L was added for peptization, and then deionized water was added to a total mass of 402 g to obtain an aluminum hydroxide sol with a solid content of 20% by weight. Finally, γ-Al2O3 beads L were obtained, with a bead yield of 94.3% by weight.

[0193] The pore diameter distribution of the γ-Al2O3 beads L is shown in Table 2, and the crushing strength and other physicochemical properties are shown in Table 3.

[0194] Comparative Example 3

[0195] The method of Example 1 was followed, except that during the preparation of the aluminum hydroxide sol, no pseudoboehmite was added, and only boehmite was used as the raw material, specifically: 100 g (alumina dry basis mass) of boehmite was added to 271 ml of a 0.19 mol / L concentration nitric acid solution for peptization, then deionized water was added to a total mass of 405 grams, to obtain an aluminum hydroxide sol with a solid content of 20% by weight. Finally, γ-Al2O3 pellets M were obtained, with a pelletization yield of 89.1% by weight.

[0196] The pore diameter distribution of the γ-Al2O3 pellets M is shown in Table 2, and the crushing strength and other physicochemical properties are shown in Table 3.

[0197] Comparative Example 4

[0198] The method of Example 1 was followed, except that during the preparation of the boehmite, no grain structure regulator was added to the aluminum hydroxide slurry, and after stirring uniformly, the aluminum hydroxide slurry was transferred to a stainless steel pressure kettle, and aged at 120°C for 12 h without stirring. After aging, the slurry was washed with deionized water, then placed in an oven and dried at 120°C for 12 h, and then ground to obtain boehmite powder. Finally, γ-Al2O3 pellets N were obtained, with a pelletization yield of 94.6% by weight.

[0199] The pore diameter distribution of the γ-Al2O3 pellets N is shown in Table 2, and the crushing strength and other physicochemical properties are shown in Table 3.

[0200] Table 1

[0201]

[0202] Table 2

[0203]

[0204]

[0205] As can be seen from Table 2, compared with the γ-Al2O3 pellets prepared in the comparative examples, in the γ-Al2O3 pellets provided by the present application, the proportion of pores with a pore diameter of 10-50 nm is more than 80%, and the proportion of pores with a pore diameter of 10-20 nm is >60%, and the proportion of pores with a pore diameter of 20-50 nm is >10%.

[0206] Table 3

[0207]

[0208] As can be seen from Table 3, the γ-Al2O3 pellets provided by the present application have a high degree of sphericity and crushing strength, and the continuous reforming catalyst using the spheroidal alumina as the carrier is less likely to break during use, reduces the abrasion rate, and prolongs the operating cycle of the catalyst.

[0209] Test Example 1

[0210] 50 g of the γ-Al2O3spheres (A, C, H, K-N) prepared in the examples and comparative examples (calculated on the basis of the alumina dry basis) were taken as the carrier, and 90 g of a solution containing chloroplatinic acid, SnCl2and hydrochloric acid was taken as the impregnation liquid, the impregnation liquid containing 0.29 wt% of Pt, 0.3 wt% of Sn and 1.2 wt% of chlorine (all relative to the mass of the alumina carrier dry basis). The γ-Al2O3spheres A were impregnated with the impregnation liquid at 25°C for 4 hours, the impregnated solid was dried at 120°C for 10 hours, and then water-chlorine activation treatment was carried out at 510°C for 8 hours using air containing hydrogen chloride and water, the molar ratio of water / HCl in the air being 50:1, and then hydrogen reduction was carried out at this temperature for 4 hours, to obtain a catalyst CatA, wherein the Pt content was 0.29 wt% and the Sn content was 0.3 wt% and the Cl content was 1.1 wt% based on the carrier.

[0211] The catalyst was packed in a 100 ml medium evaluation device, and the refined straight-run naphtha with the composition described in Table 4 was used as the raw material to evaluate the reaction performance of the catalyst. The evaluation conditions were: 530°C, 0.7 MPa, hydrogen / hydrocarbon volume ratio 800 / 1, naphtha feed volume space velocity 2 h-1, cumulative reaction time 120 hours, and the evaluation results of each catalyst are shown in Table 5. -1 The product liquid yield and the aromatic content are the average results of 120 hours of reaction, and the carbon deposition amount is the carbon deposition amount of the catalyst after 120 hours of reaction. 5+

[0212] Table 4

[0213]

[0214] Table 5

[0215]

[0216]

[0217] As can be seen from the results in Table 5, compared with the comparative examples, the continuous reforming catalyst obtained by using the spherical alumina provided in the examples as the carrier has higher aromatic yield and relatively low carbon deposition amount when applied to the naphtha continuous reforming process, and is suitable for use in the aromatic continuous reforming device.

[0218] 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 fall within the protection scope of the present application.​

Claims

1. A spherical alumina, characterized in that, In the spherical alumina, pores with a diameter of 6-10 nm account for 10-22% of the total pore volume, pores with a diameter of 10-20 nm account for 50-75% of the total pore volume, and pores with a diameter of 20-50 nm account for 10-25% of the total pore volume. The 10nm diameter endpoint is contained within a 10-20nm diameter pore, and the 20nm diameter endpoint is contained within a 20-50nm diameter pore. The method for preparing the spherical alumina includes the following steps: (1) Boehmite and boehmite are soluble to obtain aluminum hydroxide slurry; (2) Aluminum hydroxide slurry is dripped into an oil-ammonia column to form wet aluminum hydroxide pellets, and then the wet aluminum hydroxide pellets are dried and calcined; The grain size of the boehmite conforms to: D (200) / D (002) =0.5-1.5, D (200) / D (020) = 0.7-1.5, where D (020) D (200) and D (002) The grain size is calculated by the Scherrer formula based on the half-peak width of the diffraction peaks along the (020), (200), and (002) crystal planes in the X-ray diffraction curves of boehmite. In the pseudoboehmite, D (120) Less than 10nm, wherein the D (120) The grain size is calculated using the Scherrer formula based on the half-width of the diffraction peak along the (120) crystal plane in the X-ray diffraction curve of boehmite. Based on the total dry basis mass of boehmite and boehmite, the dry basis mass content of boehmite is 20-50%, and the dry basis mass content of boehmite is 50-80%.

2. The spherical alumina according to claim 1, wherein, In the spherical alumina, pores with a diameter of 6-10 nm account for 12-22% of the total pore volume, pores with a diameter of 10-20 nm account for 55-75% of the total pore volume, and pores with a diameter of 20-50 nm account for 10-20% of the total pore volume.

3. The spherical alumina according to claim 1, wherein, The spherical alumina does not contain pores with a diameter less than 6 nm.

4. The spherical alumina according to claim 1, wherein, In the spherical alumina, pores with a diameter greater than 50 nm account for less than 5% of the total pore volume.

5. The spherical alumina according to claim 1, wherein, The spherical alumina is γ-alumina.

6. The spherical alumina according to claim 1, wherein, The specific surface area of ​​the spherical alumina is 190-230 m². 2 / g; The pore volume of the spherical alumina is 0.6-0.9 cm³. 3 / g; The average particle size of the spherical alumina is 1.4-1.8 mm.

7. The spherical alumina according to any one of claims 1-6, wherein, The sphericity of the spherical alumina is greater than 0.95; The Q of the spherical alumina 0.95 Greater than 95% by volume, of which Q 0.95 This represents the volume percentage of spherical alumina particles with a sphericity greater than 0.95 among all spherical alumina particles.

8. The spherical alumina according to any one of claims 1-6, wherein, The crushing strength of the spherical alumina is 45-80 N / particle.

9. A method for preparing spherical alumina, the method comprising the following steps: (1) Boehmite and boehmite are soluble to obtain aluminum hydroxide slurry; (2) Aluminum hydroxide slurry is dripped into an oil-ammonia column to form wet aluminum hydroxide pellets, and then the wet aluminum hydroxide pellets are dried and calcined; The grain size of the boehmite conforms to: D (200) / D (002) =0.5-1.5, D (200) / D (020) = 0.7-1.5, where D (020) D (200) and D (002) The grain size is calculated by the Scherrer formula based on the half-peak width of the diffraction peaks along the (020), (200), and (002) crystal planes in the X-ray diffraction curves of boehmite. In the pseudoboehmite, D (120) Less than 10nm, wherein the D (120) The grain size is calculated using the Scherrer formula based on the half-width of the diffraction peak along the (120) crystal plane in the X-ray diffraction curve of boehmite. Based on the total dry basis mass of boehmite and boehmite, the dry basis mass content of boehmite is 20-50%, and the dry basis mass content of boehmite is 50-80%.

10. The method according to claim 9, wherein, The grain size of the boehmite conforms to: D (200) / D (002) =0.6-1.3, D (200) / D (020) =0.8-1.

5.

11. The method according to claim 9, wherein, The boehmite has a particle size of 0.1-500 μm; The D of the boehmite 50 It ranges from 40 to 200 μm.

12. The method according to claim 11, wherein, The boehmite has a particle size of 0.1-400 μm; The D of the boehmite 50 It is 40-100μm.

13. The method according to claim 9, wherein, In the pseudoboehmite, D (120) Less than 6nm.

14. The method according to claim 9, wherein, The particle size of the pseudoboehmite is 0.1-300 μm; The pseudoboehmite D 50 It is 5-60μm.

15. The method according to claim 14, wherein, The particle size of the pseudoboehmite is 0.5-200 μm; The pseudoboehmite D 50 It is 30-60μm.

16. The method according to any one of claims 9-15, wherein, Based on the total dry basis mass of boehmite and boehmite, the dry basis mass content of boehmite is 20-40%, and the dry basis mass content of boehmite is 60-80%.

17. The method according to any one of claims 9-15, wherein, The acid used in the colloid in step (1) is an inorganic acid and / or an organic acid, wherein the inorganic acid is nitric acid and / or hydrochloric acid, and the organic acid is selected from at least one of trichloroacetic acid, formic acid and citric acid; The ratio of the mass of acid used in the sol-gel process in step (1) to the total mass of boehmite and boehmite (calculated as alumina) is 0.01-0.

1. The acid used in step (1) is provided in the form of an acid solution with a concentration of 0.1-2 mol / L.

18. The method according to any one of claims 9-15, wherein, The solid content of the aluminum hydroxide slurry obtained in step (1) is 15-28% by weight.

19. The method according to any one of claims 9-15, wherein, The oil-ammonia column comprises an organic phase and an ammonia-water phase, wherein the height ratio of the organic phase to the ammonia-water phase is 1:5-300. The organic phase is C5-C. 20 Alkanes.

20. The method according to claim 19, wherein, The organic phase is selected from at least one of gasoline, kerosene, petroleum ether, n-pentane, n-hexane, n-heptane, n-octane, n-decane, and undecane.

21. The method according to claim 19, wherein, The concentration of the ammonia phase is 6-18 by weight.

22. The method according to any one of claims 9-15, wherein, The roasting conditions in step (2) include: a temperature of 450-800℃ and a time of 2-8 hours.

23. The use of a spherical alumina according to any one of claims 1-8 or a spherical alumina prepared by any one of claims 9-22 in catalyst preparation.

24. The application according to claim 23, wherein, The catalyst is a continuous reforming catalyst.

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