Stable shaped alumina and method for producing the same

Abstract

The invention relates to calcined shaped alumina and a method of making calcined shaped alumina. The method includes hydrothermally aging alumina in an alumina suspension to have a specific crystal size. This in turn results in highly stable alumina in the form of calcined shaped alumina, particularly at temperatures of 1200°C and above.

Description

TECHNICAL FIELD

[0001] The present invention relates to calcined shaped alumina or synonymously used "calcined shaped alumina support", and to a process for preparing a calcined shaped alumina support / calcined shaped alumina. BACKGROUND

[0002] Activated alumina is widely used as a support for a variety of heterogeneous catalytic applications. On the one hand, these include fixed bed, also referred to as packed bed, while on the other hand, also moving bed or fluidized bed applications. For fixed bed applications, it is important that the prepared catalyst provides for a uniform packing of the bed to avoid channeling and temperature gradients, while for fluidized bed or moving bed applications, a key aspect is to prepare a stable and robust catalyst to avoid attrition or breakage of the catalyst particles due to impact with the reactor wall or with each other. For certain applications, it is advantageous to shape the alumina. Especially in fixed bed catalysis, a number of catalyst shapes have been proposed in the prior art to balance the difficulties experienced in terms of catalyst activity and pressure drop across the catalyst bed.

[0003] As used in the present specification, shaping refers to the process and method of agglomerating particulate matter into larger shapes, preferably shapes with a certain regularity, and shaped has the corresponding meaning. After such shaping, it is necessary to calcine the shape to provide strength and fix the shape. Thus, the skilled person in the field of the present invention will understand that calcined shaped alumina / calcined shaped alumina support refers to, for example, alumina spheres, alumina extrudates and alumina tablets, which are preferably shaped in a forming tower.

[0004] US 4542113 provides a process for preparing spherical alumina from boehmite alumina. The spheres obtained by the disclosed process are said to have a diameter of 2-3 mm, a compressive strength of up to 200 N / sphere, a pore volume of 0.45-0.75 mL / g and a surface area of 220-250 m 2 / g.

[0005] There is still a need for improved shaped catalyst supports having specific properties, in particular a combination of specific properties. SUMMARY

[0006] According to a first aspect of the present invention, there is provided a calcined shaped alumina / calcined shaped alumina support comprising the following features a) and b):

[0007] a) a compressive strength of 30-70 N, preferably 40-60 N; and

[0008] b) a monodisperse pore radius distribution with a median pore radius of 5-12 nm, preferably 7-10 nm.

[0009] Preferably the calcined shaped alumina further comprises one or more of the following features c) to f), and preferably all features c) to f):

[0010] c) 0.4 to 1.2 cm 3 / g, preferably 0.7 to 1.0 cm 3 / g total pore volume;

[0011] d) a BET surface area of 10 to 100 m 2 / g after calcination at 1200 °C for 3 hours, preferably a BET surface area of 40 to 80 m 2 / g after calcination at 1200 °C for 3 hours;

[0012] e) a Na, Fe and Si impurity content of the calcined shaped alumina of less than 100 ppm each, preferably less than 50 ppm each; and

[0013] f) an alpha transformation temperature of more than 1200 °C, preferably more than 1300 °C.

[0014] Preferably the calcined shaped alumina comprising features a) and b) further comprises at least feature c).

[0015] The calcined shaped alumina can be produced according to the following method.

[0016] According to a further aspect of the present application there is provided a method of producing a calcined shaped alumina, the method comprising the following steps:

[0017] i) producing an alumina suspension, the alumina suspension comprising alumina and at least water;

[0018] ii) hydrothermally ageing the alumina suspension until the alumina in the alumina suspension has a crystal size of each along the (120) and (020) axis to form a hydrothermally aged alumina suspension;

[0019] iii) optionally drying the hydrothermally aged alumina suspension to obtain an alumina powder;

[0020] iv) optionally producing an alumina paste from the alumina powder or an alumina dispersion from the alumina powder or the hydrothermally aged alumina suspension;

[0021] v) shaping the alumina powder or the alumina paste or the alumina dispersion or the hydrothermally aged alumina suspension or a mixture thereof to form a shaped alumina;

[0022] vi) drying the shaped alumina to form a dried shaped alumina; and

[0023] vii) calcining the dry shaped alumina to form a calcined shaped alumina.

[0024] Step iv) is optional, as the alumina powder of step iii) can be directly shaped in step v). Step iii) is optional, as the hydrothermally aged alumina suspension of step ii) can be directly used in step iv) or v).

[0025] The calcined shaped alumina is a calcined shaped alumina support or can be used as a support for heterogeneous catalytic applications. BRIEF DESCRIPTION OF DRAWINGS

[0026] The present invention will now be described with reference to the non-limiting examples and the accompanying drawings, in which:

[0027] Figure 1 shows the pore radius distribution of comparative examples 1 and 2 (samples 1 and 2) and examples 1 and 6 (samples 3a and 7);

[0028] Figure 2 shows the pore radius distribution of examples 1 and 2 calcined at different temperatures;

[0029] Figure 3 shows the pore radius distribution of examples 4 and 5 (samples 5 and 6) comprising different dopants;

[0030] Figure 4 shows the DSC (differential scanning calorimetry) - TG (thermogravimetry) analysis of comparative example 1 and example 1 ; and

[0031] Figure 5 is the X-ray diffraction pattern of comparative example 2 and example 1 after calcination at 1200 °C for 3 hours;

[0032] Figure 6 shows the pore radius distribution of comparative example 3. DETAILED DESCRIPTION

[0033] The calcined shaped alumina can be in the form of spheres, extrudates, tablets or mixtures thereof, preferably shaped in a shaping tower. The calcined shaped alumina is preferably in the form of spheres, i.e. spherical alumina. In the present invention, spheres or spheroids refer to spheres having a sphericity preferably higher than 0.9.

[0034] The formation of the spheroidal alumina in the forming tower depends on the introduction of the alumina-containing sol, solution or other mixture as droplets into a liquid, which is then converted into spheroids. Many variations and improvements are known to the person skilled in the art, which are particularly suitable for the shaping of spheroidal alumina particles and are described, for example, in US 4542113 and the techniques cited therein. The disclosure of US 4542113 is incorporated herein by reference, in particular with regard to the shaping by use of a forming tower.

[0035] The longest dimension of the calcined shaped alumina is at least 0.5 mm (for spheroids, the longest dimension is, for example, the diameter). When the calcined shaped alumina is in the form of spheroidal alumina, it can comprise further features with a diameter of 0.5 mm to 3.0 mm.

[0036] The diameter of the spheroidal alumina is determined according to the ASTM D1155 standard.

[0037] According to one embodiment, the calcined shaped alumina comprises a monodisperse pore radius distribution. A monodisperse pore radius distribution means a pore radius distribution obtained by the mercury intrusion method (DIN 66133), in which for radii in the range from 1 to 100 nm only one global maximum is determined without local maxima (i.e. the pore radius distribution is unimodal). This is one of the advantages of the present application, since in the past two maxima were expected. The calcined shaped alumina of the present application comprises a median pore radius of 5 to 12 nm, preferably 7 to 10 nm.

[0038] The pore radius distribution, and thus the total pore volume, is measured using the standard DIN 66133 (determination of pore volume distribution and specific solid surface by mercury intrusion method).

[0039] It is known that the thermal conversion of the different phases of alumina ultimately leads to the formation of a-alumina when the temperature is increased. In general, the last step of the thermal conversion is the phase transition from the theta phase to the alpha phase. The transition to the alpha phase is accompanied by a loss of porosity and surface area, while a-alumina powders produced by high-temperature calcination are usually characterized by a low BET surface area of about 5 m 2 / g.

[0040] According to one embodiment, the calcined shaped alumina of the present application is characterized by an excellent thermal stability, i.e. wherein the alumina resists phase transformation to the alpha phase and remains in the theta phase. Even in case phase transformation to the alpha phase does occur, the calcined alumina of the present application is characterized by a larger surface area than expected for typical alpha aluminas. The term "thermal stability" as used herein refers to thermal stability to surface and / or crystal phase changes, which are caused by temperature changes, possibly together with other external influences such as water, chemicals, pressure and mechanical stress. For example, the thermal stability can be characterized by the surface area, as determined according to DIN ISO 9277 using the BET method with nitrogen, which is the surface area retained by the sample after calcination in a muffle furnace at 1200 °C for 3 hours or at 1300 °C for 3 hours (heating rate 1 K / min - 10 K / min).

[0041] The calcined shaped alumina can further comprise a dopant. The dopant preferably comprises rare earth elements, transition elements (elements of group 3 to 11 of the periodic table, in particular elements of group 4 to 11, in particular elements of group 4 (old IUPAC numbering IVb) and group 5 (old IUPAC numbering Vb) of the periodic table) and tin and bismuth. The amount of dopant added is 0 to 1 wt% or more than 0 to 1 wt%, preferably 0 to 0.5 wt% or more than 0 to 0.5 wt%, the weight of the dopant being calculated as the element and the wt% being relative to the calcined shaped alumina. Preferably, the calcined shaped alumina is doped with organic and inorganic salts of transition elements, rare earth elements and elements of group 4 (old IUPAC numbering IVb) and group 5 (old IUPAC numbering Vb) of the periodic table (more preferably Sn and Bi). Most preferably, the calcined shaped alumina is doped with SnCI4or Bi(N03)3x 5H20.

[0042] The preferred embodiments of the process according to the present application are further defined as follows:

[0043] The calcined shaped alumina can be in the form of spheroids, extrudates, tablets, or mixtures thereof, which are preferably shaped in a shaping column. The maximum dimension of the calcined shaped alumina is at least 0.5 mm (for spheroids, the maximum dimension is for example the diameter). The calcined shaped alumina is preferably a spheroid, i.e. a spherical alumina.

[0044] The alumina suspension comprises alumina and at least water. The alumina content in the alumina suspension, calculated as AI2O3, is preferably in the range of 2 wt% to 20 wt%, more preferably in the range of 5 wt% to 10 wt%, of the alumina suspension. The alumina suspension is preferably obtained by hydrolysis of an alkoxide.

[0045] The alumina in the alumina suspension can comprise boehmite, gibbsite, bayerite, transition alumina (at least comprising gamma-alumina, delta-alumina and theta-alumina), and most preferably boehmite. The boehmite alumina can be obtained, for example, by hydrolysis of an aluminium alkoxide in water.

[0046] The desired crystal dimensions along the (120) and (020) axes are obtained by hydrothermally ageing the alumina suspension, wherein at least the hydrothermally aged alumina suspension comprises boehmite. The hydrothermal ageing reaction is typically carried out at a temperature of 60-300°C, preferably 80-180°C, for a period of 1-30 hours, preferably 15-30 hours, under stirring.

[0047] The temperature and time are independently selected. The boehmite after hydrothermal ageing preferably has a crystal dimension along the (120) axis and a crystal dimension along the (020) axis, each of which is More preferably, the boehmite after hydrothermal ageing has a ratio of the crystal dimension along the (120) axis to the crystal dimension along the (020) axis of 0.5:1 to 2.0:1, preferably 0.9:1 to 1.1:1.

[0048] The alumina dispersion comprises alumina and at least water. The alumina content in the alumina dispersion, measured as AI2O3, is 10wt% to 40wt%, preferably 25wt% to 35wt%.

[0049] The alumina dispersion preferably comprises an acid. The acid that can be used is an organic acid or an inorganic acid, preferably nitric acid, acetic acid, formic acid or a mixture thereof. The concentration of the acid in the alumina dispersion can be 0.1wt% to 1.5wt%, preferably 0.9wt% to 1.2wt%. The particle size of the alumina in the dispersion is preferably below 1 μm, preferably below 500 nm.

[0050] Furthermore, the alumina dispersion can comprise a hydrocarbon having a boiling point higher than 250°C, in particular kerosene. The amount of hydrocarbon, in particular kerosene, contained in the alumina dispersion can be greater than 0 to 10wt% of the alumina dispersion, preferably greater than 0 to 5wt% of the alumina dispersion. Kerosene refers to a liquid mixture of branched and unbranched alkanes. According to EINECS 232-384-2, typical kerosene has a specific gravity of 0.81 to 0.89 g / cm 3 , a boiling point higher than 250°C.

[0051] The dopant can be added to the alumina paste, or the alumina dispersion, or the hydrothermally aged alumina suspension or mixtures thereof prior to shaping to form the shaped alumina. The dopant preferably comprises rare earth elements, transition elements (elements of groups 3 to 11 of the periodic table, preferably groups 4 to 11, in particular elements of group 4 (old IUPAC numbering IVb) and group 5 (old IUPAC numbering Vb) of the periodic table) and tin and bismuth. When adding the dopant to the alumina dispersion, the alumina dispersion preferably comprises 0 to 1 wt% or more than 0 to 1 wt%, preferably 0 to 0.5 wt% or more than 0 to 0.5 wt% of the dopant, the weight of the dopant being calculated as element and relative to the weight of the calcined shaped alumina.

[0052] Preferably the alumina dispersion comprises organic and inorganic salts of rare earth elements and transition elements, in particular elements of group 4 (old IUPAC numbering IVb) and group 5 (old IUPAC numbering Vb) of the periodic table, more preferably Sn and Bi. Most preferably the alumina dispersion comprises SnCI4or Bi(N03)3x 5H20. Tin and bismuth are generally included for their catalytic effect.

[0053] The alumina paste preferably comprises alumina and an acid. The alumina content in the alumina paste, measured as AI2O3, can be in the range of 20 wt% to 65 wt%, preferably 40 wt% to 60 wt%. The acid that can be used is an organic acid or an inorganic acid, preferably nitric acid, acetic acid, formic acid or mixtures thereof. The concentration of the acid in the alumina paste can be in the range of 0.1 wt% to 4.0 wt%, preferably 1.0 wt% to 2.5 wt%.

[0054] Preferably the alumina dispersion is prepared from an alumina powder.

[0055] The calcined shaped alumina of the present invention is obtained by shaping the alumina powder, or the alumina paste, or the alumina dispersion or the hydrothermally aged alumina suspension or mixtures thereof using various techniques known in the art. For example, to prepare spheroids, the alumina dispersion is dropped in the form of droplets into a forming tower. To form extrudates or tablets, the alumina powder or the alumina paste is extruded or pressed using techniques known in the art.

[0056] According to one embodiment of the present invention, the shaped alumina is preferably dried at a temperature in the range of 90 to 150°C, more preferably in the range of 110 to 130°C, and preferably independently thereof by using a static oven or a belt dryer with a residence time in the range of 2 to 24 hours. Such drying techniques are known to the person skilled in the art.

[0057] According to one embodiment of the invention, calcination is carried out at a temperature of 450-1100°C, preferably 550-750°C, typically in a muffle furnace or kiln, with a residence time of 10 minutes to 10 hours, preferably 2-4 hours. The temperature and time are selected independently.

[0058] Example

[0059] Analytical methods and definitions

[0060] The crystal size of boehmite according to the invention is determined using the general Scherrer formula along the (120) and (020) axes:

[0061] Crystal size = (K × λ × 57.3) / (β × cosθ)

[0062] in:

[0063] K (shape factor): 0.992

[0064] λ (X-ray wavelength): 0.154 nm

[0065] β (instrument calibration line broadening): Reflex dependent

[0066] θ: Reflection dependency

[0067] Using Bruker CubiX 3 The instrument performs these measurements. The measurement parameters for boehmite are θ = 14° for reflection along the (120) axis and θ = 7° for reflection along the (020) axis, with β = 0.919 for both reflections.

[0068] The specific surface area provided in this article is measured according to DIN-ISO 9277 using the BET method with nitrogen.

[0069] According to DIN 66133, the orifice volume is measured using the mercury immersion method (for orifice radii ranging up to...). (The situation) and pore radius distribution. The mesopore radius is the radius corresponding to the 50th percentile of the pore volume, that is, the radius at which half of the pore volume is found in the larger pores and half in the smaller pores.

[0070] The diameter of the spherical alumina was determined according to ASTM D1155.

[0071] The crushing strength of extruded materials is determined according to ASTM D6175, while the crushing strength of other shapes is determined according to ASTM D4179.

[0072] DSC is determined according to DIN 51007.

[0073] Sphericity was determined by dynamic imaging analysis using a Retsch Camsizer P4 as described in ISO 13322-2 (2006). Sphericity (SPHT3) was calculated using the following formula according to the measured perimeter P and the projected area A of the particle

[0074]

[0075] The determined values are dimensionless and 1 for an ideal sphere, while for spheroidal particles of non-ideal spheres, it is usually lower than 1. In the case of the present application, the sphericity is higher than 0.9.

[0076] These procedures were performed exactly as specified.

[0077] Particle size was determined by laser diffraction (Malvern Mastersizer 2000) using Mie theory.

[0078] Preparation of the hydrothermally aged samples:

[0079] Sample A

[0080] The hydrolysis of aluminum hexanolate was performed in a 2% ammonium bicarbonate aqueous solution at 98°C. The obtained alumina suspension (= boehmite suspension) with 7.5 wt% AI2O3 was stirred at 100°C with a stirring speed of 3.2 m / s for 16 hours. The aged alumina suspension was dried in a spray dryer (inlet temperature: 120°C). A boehmite powder with a crystal size of The crystal size along the (020) axis was

[0081] Sample B The hydrolysis of aluminum hexanolate was performed in a 2% ammonium bicarbonate aqueous solution at 98°C. The obtained alumina suspension (= boehmite suspension) with 7.5 wt% AI2O3 calculated as AI2O3 was stirred at 100°C with a stirring speed of 3.2 m / s for 16 hours. The aged alumina suspension was dried in a spray dryer (inlet temperature: 120°C). A boehmite powder with a crystal size of

[0082] The crystal size along the (020) axis was

[0083] Example 1 = Sample 3a

[0084] Experiment

[0085]

[0086] ​​​An alumina dispersion was prepared by dispersing boehmite according to sample A in acidic water. The dispersion contained 32.5 wt% boehmite (calculated as AI2O3) and 0.03 g nitric acid per g boehmite. After stirring for 10 minutes, the sol was added in the form of droplets to a forming column at a temperature of 20-25°C, which was filled with 8 wt% ammonia solution. The green pellets discharged from the forming column were dried at 120°C until constant weight was obtained. The dried pellets were calcined at 650°C for 3 hours.

[0087] Example 2 = sample 3b

[0088] Example 2 was carried out as example 1, but the dried pellets were calcined at 950°C for 3 hours.

[0089] Example 3 = sample 4

[0090] Example 3 was carried out as example 1, but the boehmite starting alumina was sample B.

[0091] Example 4 = sample 5

[0092] Example 4 was carried out as example 3, but in addition to boehmite, water and acid, the dispersion contained the dopant SnCI4x 2H2O, which corresponds to 0.4 wt% Sn, calculated as SnO2and based on the calcined alumina pellets.

[0093] Example 5 = sample 6

[0094] Example 5 was carried out as example 3, but in addition to boehmite, water and acid, the dispersion contained the dopant Bi(NO3)3x 5H2O, which corresponds to 0.1 wt% Bi, calculated as Bi2O3and based on the calcined alumina pellets.

[0095] Example 6 = sample 7

[0096] Example 6 was carried out as example 3, but in addition to boehmite, water and acid, the dispersion contained 0.1 g kerosene per g boehmite.

[0097] Example 7 = sample 8 (extrudates)

[0098] An alumina paste was made by mixing 1500 g sample B with 1250 g 4 wt% acetic acid in a high shear mixer for 15 minutes. The paste was pressed through a hole disc to obtain extrudates with a diameter of 1.69 mm. The green bodies were dried at 120°C until constant weight was obtained. The dried extrudates were calcined at 650°C for 3 hours.

[0099] Example 8 = sample 9 (tablets)

[0100] Boehmite powder of sample B was pressed into a tablet (5.1 x 5.2 mm) by methods known in the art and calcined at 650°C for 3 hours.

[0101] Comparative Example 1 = Sample 1 (no kerosene)

[0102] An alumina dispersion was prepared by mixing boehmite powder having a crystal size of along the (120) axis and along the (020) axis in acidic water without an aging step. The dispersion contained 32.5 wt% solids and 0.03 g nitric acid per g boehmite. After stirring for 10 minutes, the sol was fed as droplets into a forming column at a temperature of 20-25°C, which was filled with 8 wt% ammonia solution. The green pellets discharged from the forming column were dried at 120°C until constant weight. The dried pellets were calcined at 650°C for 3 hours.

[0103] Comparative Example 2 = Sample 2 (with kerosene)

[0104] Comparative Example 2 was performed as Comparative Example 1 except that the dispersion contained 0.1 g kerosene per g boehmite in addition to the boehmite, water and acid.

[0105] A summary of Examples and Comparative Examples 1 and 2, including results, is included in Table 1 below.

[0106] Figure 1 The pore radius distribution of Comparative Example 1 (Sample 1), Comparative Example 2 (Sample 2) and Example 1 (Sample 3a), Example 6 (Sample 7) were compared. According to Figure 1 It is clear that the mesopore radius of Comparative Example 1 is lower than the mesopore radius of the inventive examples. Figure 2 The pore radius distribution of Examples 1 and 2, which have the same starting material but are calcined at different temperatures, are shown. Figure 3 The pore radius distribution of Examples 4 and 5 (Samples 5 and 6), which have different dopants, are shown. Figure 4 is a DSC (differential scanning calorimetry) curve showing the phase transformation of alumina according to Comparative Example 1 (Sample 1) and Example 1 (Sample 3a). As shown, Comparative Example 1 (Sample 1) is characterized by a phase transformation to the alpha phase at 1188.6°C, while Example 1 (Sample 3a), prepared according to the invention, shows a phase transformation to the alpha phase at 1314°C. The phase transformation to the alpha phase is accompanied by a decrease in surface area. Figure 5 A comparison of Comparative Example 2 (Sample 2) and Example 1 (Sample 3a) after calcination at 1200°C for 3 hours is shown. Comparative Example 2 shows the alpha phase, while Example 2 shows only the theta phase.

[0107]

[0108] Comparative Example 3 (Example 5 of US 4542113)

[0109] Comparative Example 3 was performed by modifying Example 5 of US 4542113. The exact same experimental procedure was used. The starting material was a mixture of two boehmites having the following properties:

[0110] Table 2

[0111]

[0112] The properties of the resulting material were compared to those reported in Example 5 of US 4542113 and the conclusion was that the modification was representative (see Table 3).

[0113] Table 3:

[0114]

[0115] Figure 6 The pore radius distribution of Comparative Example 3 is shown. The measured mesopore size was 4.9 nm, while the pore radius distribution was bimodal.

Claims

1. A calcined shaped alumina comprising features a), b), c), and f): a) a crush strength of 30-70 N; b) a monodisperse pore radius distribution with a median pore radius of 5-12 nm; c) 0.4 - 1.2 cm 3 total pore volume of 0.1 to 1.5 cm3 / g, and f) an alpha phase transition temperature higher than 1200°C, wherein the calcined shaped alumina is in the form of spheroids, extrudates, tablets, or mixtures thereof having a sphericity higher than 0.

9.

2. The calcined shaped alumina of claim 1, wherein the crush strength is 40-60 N.

3. The calcined shaped alumina of claim 1 or claim 2, wherein the median pore radius is 7-10 nm.

4. The calcined shaped alumina of claim 1, further comprising one or more of features c)-e): c) 0.7 - 1.0 cm 3 total pore volume of 0.1 to 1.0 cm3 / g; d) after calcination at 1200 °C for 3 hours, a BET surface area of 10-100 m 2 / g; and e) the calcined shaped alumina has a Na, Fe, and Si impurity content each lower than 100 ppm.

5. The calcined shaped alumina of claim 4, comprising all features c)-e).

6. The calcined shaped alumina of claim 4 or claim 5, having a BET surface area of 40-80 m2 / g after calcination at 1200°C for 3 hours. 2 / g after calcination at 1200°C for 3 hours.

7. The calcined shaped alumina of claim 4 or claim 5, wherein the calcined shaped alumina has a Na, Fe, and Si impurity content each lower than 50 ppm.

8. The calcined shaped alumina of claim 4 or claim 5, having an alpha phase transition temperature higher than 1300°C.

9. The calcined shaped alumina of claim 1 or claim 2, wherein the calcined shaped alumina is in the form of spheroids having a sphericity higher than 0.

9.

10. The calcined shaped alumina of claim 9, wherein the spheroids comprise a diameter of 0.5 mm-3.0 mm.

11. The calcined shaped alumina of claim 1 or claim 2, comprising one or more dopants selected from the group consisting of tin, bismuth, and transition elements.

12. The calcined shaped alumina of claim 11, wherein the one or more dopants are selected from the group consisting of Group IVb elements, Group Vb elements, and rare earth elements.

13. A method of making a calcined shaped alumina, the method comprising the steps of: i) preparing an alumina suspension comprising alumina and at least water, the alumina comprising boehmite; ii) hydrothermally aging the alumina suspension until the boehmite in the alumina suspension has a crystal size along the (120) and (020) axes each of 70-110 A, thereby forming a hydrothermally aged alumina suspension, iii) shaping to form a shaped alumina; vi) drying the shaped alumina to form a dried shaped alumina; and vii) calcining the dried shaped alumina at a temperature of 450°C-1100°C for 10 minutes to 10 hours to form a calcined shaped alumina; wherein the calcined shaped alumina is in the form of spheroids, extrudates, tablets, or mixtures thereof having a sphericity higher than 0.

9.

14. The method of claim 13, wherein the calcined shaped alumina is in the form of spheroids having a sphericity higher than 0.

9.

15. The method of claim 13 or claim 14, comprising an intermediate step of drying the hydrothermally aged alumina suspension to obtain an alumina powder prior to shaping to form shaped alumina.

16. The method of claim 15, comprising an intermediate step of preparing an alumina paste from the alumina powder prior to shaping to form shaped alumina.

17. The method of claim 15, comprising an intermediate step of preparing an alumina dispersion from the alumina powder prior to shaping to form shaped alumina.

18. The method of claim 13, comprising an intermediate step of preparing an alumina dispersion from the hydrothermally aged alumina suspension prior to shaping to form shaped alumina.

19. The method of claim 13 or claim 14, wherein the alumina content of the alumina suspension, calculated as AI2O3, is 2-20 wt%.

20. The method of claim 19, wherein the alumina content is 5-10 wt% of the alumina suspension.

21. The method of claim 17 or claim 18, wherein the alumina content of the alumina dispersion, calculated as AI2O3, is 10-40 wt%.

22. The method of claim 21, wherein the alumina content is 25-35 wt% of the alumina dispersion.

23. The method of claim 17 or claim 18, wherein the alumina dispersion comprises an acid.

24. The method of claim 17 or claim 18, wherein the alumina dispersion comprises kerosene, wherein the amount of kerosene in the alumina dispersion is between greater than 0 and 10 wt% of the alumina dispersion.

25. The method of claim 24, wherein the amount of kerosene is between greater than 0 and 5 wt% of the alumina dispersion.

26. The method of claim 13 or claim 14, wherein one or more dopants are added prior to shaping to form the shaped alumina, the one or more dopants selected from the group consisting of tin, bismuth, and transition elements.

27. The method of claim 26, wherein the one or more dopants are selected from the group consisting of Group IVb elements, Group Vb elements, and rare earth elements.

28. The method of claim 13 or claim 14, wherein the boehmite has a ratio of crystal size along the (120) axis to crystal size along the (020) axis of 0.5: 1 to 2.0: 1 after hydrothermal aging.

29. The method of claim 28, wherein the boehmite has a ratio of crystal size along the (120) axis to crystal size along the (020) axis of 0.9: 1 to 1.1: 1 after hydrothermal aging.

30. The method of claim 13 or claim 14, wherein the hydrothermal aging reaction is carried out at a temperature of 60 °C to 300 °C for 1 to 30 hours.

31. The method of claim 30, wherein the hydrothermal aging reaction is conducted at a temperature of 80 °C to 180 °C for 15 to 30 hours.

32. The method of claim 13 or claim 14, wherein the shaped alumina is dried at a temperature of 90 °C to 150 °C for 2 to 24 hours.

33. The method of claim 32, wherein the shaped alumina is dried at a temperature of 110 °C to 130 °C.

34. The method of claim 13 or claim 14, wherein calcination is conducted at a temperature of 550 °C to 750 °C for 2 to 4 hours.

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