DE19843241A1 - Mesoporous aluminum oxide, useful as catalyst, catalyst support or adsorbent, obtained by hydrolysis of aluminum alkoxide in non-aqueous solvent in presence of carboxylic acid tert. amine pore regulator - Google Patents

Abstract

Mesoporous aluminum oxide with a BET surface of 500-900 m<2>/g, a pore volume of 0.4-1.0 cm<3>/g and high thermal stability in the sense that the X-ray diffraction spectrum (Guinier) shows no crystalline Al oxide phases at temperatures up to 1,000 deg C, containing only mesopores with minimum and average diameters of 1 nm and 2-5 nm respectively. Independent claims are also included for: (i) mesoporous Al oxides (MPAO) as defined above, obtained by a process as described below; and (ii) a process for the production of MPAO by the controlled addition of water to a monomeric Al alkoxide in presence of a pore-regulating additive selected from: (a) an equimolar mixture of optionally unsaturated 5-21C mono- or di-carboxylic acid(s) and tert. amine(s) of formula (I): or (b) alkylammonium salts of formula (II),in a non-aqueous solvent for 1-60 minutes at between room temperature and 100 deg C, followed by drying the precipitate and removing the regulator. NR<2>R<3>R<4> (I) R<1>COO<-> (HNR<2>R<3>R<4>)<+> (II) R<2>, R<3>, R<4> = 1-20C alkyl or 1-10C hydroxyalkyl; R<1> = 5-20C alkyl or optionally unsaturated carboxylic acid residue.

Description

The invention relates to mesoporous, surface-rich Aluminum oxides, which act as catalysts, as a support material for Catalysts and can be used as adsorbents and a process for their production.

Crystalline aluminum oxide / hydroxide phases (Table 1) have texture porosity, which is characterized by macropores (5-30 nm diameter) with a broad radius distribution. The BET surface areas are in the range of 200-300 m ² / g.

Table 1

The main structure types of crystalline aluminum oxides and hydroxides

Hydrargillite can be dehydrated to boehmite at 100 ° C and converts to anhydrous γ-Al ₂ O ₃ at 150 ° C, to α-Al ₂ O ₃ at temperatures above 800 ° C.

The aluminum compounds of the γ series are used after dehydration or per se (γ-Al ₂ O ₃ ) as a catalyst, as a support for catalysts and as adsorbents for chromatography, but also as a component of mineral fibers (e.g. product Saffil from ICI). Microcrystalline aluminum hydroxides are used in the cosmetic industry as an additive to toothpaste, as a filler and in the glass industry as an additive to the melt (2-4% by mass).

The synthesis of aluminum oxide aerogels with specific surfaces of approximately 500 m ² / g has been described in the open literature (C.-M. Chen et al. Stud. Surf. Sci. Catal. 1995, 91, 427). However, the pore structure of these materials also came about only through texture effects.

The synthesis of silicate, mesoporous materials is described in US-A-5,057,296 and 5,098,684. The oxides are characterized as follows:

• 1. they are inorganic,
• 2. they are porous with uniform pores in the range of 1.3- 20 nm. The pore size is between that of the zeolites and the amorphous oxides,
• 3. They are crystalline insofar as they are calcined Have an x-ray diffraction pattern with at least a peak, whose position at 2Θ approx. 4.9 grd (CuKα-Strah lung) corresponds to a d value <1.8 nm and thus the d (100) - Value of the electron diffraction diagram,
• 4. They do not have a layer structure, but a hexagonal one Arrangement of non-crossing, parallel pores,
• 5. they have a large surface area (500-1000 m ² / g), the main part of which is represented by the pore wall surfaces,
• 6. They have an adsorption capacity for benzene of at least at least 15% by mass (at 25 ° C and 50 Torr benzene vapor pressure),
• 7. They are synthesized with the aid of an organic pore-regulating additive (PRZ) (here: template R) of the general structure,
  where Q = N or P, R ₁ or R ₂ or R ₃ or R _{4 present} an aryl or alkyl radical of 6-36 carbon atoms or combinations thereof and the remaining 3 groups from R ₁ -R ₄ either hydrogen or Represent alkyl residues of 1-5 carbon atoms or combinations of both.

In an improved method (US Pat. No. 5,108,725), the additional use of a further PRZ is described, selected from the group (1) of aromatic KW substances and amines of C ₅ -C ₂₀ and halogen and C ₁ -C ₁₄ - alkyl-substituted derivatives thereof, (2) cyclic, aliphatic KW substances and amines from C ₅ -C ₂₀ , including halogen and C ₁ -C ₁₄ substituted derivatives thereof, (3) polycyclic, aliphatic KW substances and amines from C ₆ -C ₂₀ including halogen and C ₁ -C ₁₄ alkyl substituted derivatives thereof, (4) straight-chain and branched KW substances and amines C ₃ -C ₁₆ , including halogen and C ₁ -C ₁₄ alkyl substituted derivatives thereof and (5) Combinations of (1) - (4). C ₁ -C ₆ alcohols, C ₁ -C ₆ diols and / or water, preferably water, are used as solvents for the organic PRZ.

No mesoporous aluminum oxides can be produced by the described processes, because in contrast to the silicic acid esters, which are used for the synthesis of silicate mesoporous materials and allow condensation in aqueous solution, aluminum alkoxides are hydrolyzed in water and as Al (OH) ₃ - Precipitation fail.

The syntheses of mesoporous aluminum oxide in aqueous phase carried out by Bagshaw and Pinnavaia (Angew. Chem. 1996, 108, 1180) were obtained in the presence of nonionic, polymeric compounds as PRZ, a high proportion of 25% by weight PRZ being necessary. After removal of the PRZ, the aluminum oxides obtained had pore diameters in the range of 2-8 nm, BET surface areas of 420-535 m ² / g and mesopore volumes of 0.21-0.68 cm ³ / g, but had a "worm-like" Channel structure that showed no periodic order of the material.

The method described by Vaudry et al. (F. Vaudry et al., Chem. Mater. 1996, 8, 1451-1464) the synthetic route followed uses carboxylic acids from C ₃ to C ₁₈ as PRZ and alcohols from C ₁ -C ₉ as solvent. According to the authors, the synthesis can also be carried out in formamide or hydrocarbons (e.g. pentane). All of Vaudry et al. The syntheses described have in common that mesoporous products with thermal stability up to 600 ° C can only be achieved after a 1-2 day synthesis time at a temperature of 100-110 ° C and prior aging of the synthesis mixture from 5 min to 24 h. The sub-steps of the synthesis are

• 1. hydrolysis of the Al alkoxide compound with 3 times molar amount of water,
• 2. stirring the suspension for a period of 1 h,
• 3. addition of the PRZ,
• 4. Aging,
• 5. Synthesis for 2-11 days at 80-200 ° C,
• 6. Filtering, washing and drying the product and
• 7. Calcining the product for thermal decomposition of the PRZ.

It is known that the hydrolysis products of aluminum Monomers in water their properties depending on the age of the never change and depending on the hydrolysis conditions Alumi nium oxides with different textural and morphological properties are formed.

The previously known and described methods are time and energy consuming, require a high Proportion of PRZ (up to 30 mol.%) And lead in the course the first, sensitive sub-step of the process, namely hydrolysis of aluminum alkoxide, too bad character precipitated products, which are extraordinary in further synthesis difference in quality of the mesoporous oxides to have.

The task of the invention was to be more structured and to develop uniformly mesoporous aluminum oxides as well an improved, less expensive method of synthesizing mesoporous alumina.

It has surprisingly been found that when used of carboxylic acid-amine mixtures as PRZ by controlled Hydrolysis of a monomeric aluminum compound already at Room temperature within a few minutes of mesoporous aluminum forms minium oxide. The "salts" used as a PRZ Carboxylic acid and an amine obviously have structure directing properties by both the acid outgoing micelle formation as well as through the tertiary or quaternary amine structure, so that the coordination of monomeric or  oligomeric hydrolysis products of aluminum do not directly the carboxylate residues take place. There is a slight ent PRZ can be removed by calcining the dried mesopo products at a maximum of 550 ° C. The procedure is in white called MESOX process (Mesoporous Oxide).

According to the invention, mesoporous aluminum oxides, characterized by

• A) uniform mesopores with a minimum diameter of 1 nm and an average diameter of 2-5 nm
• B) BET surface areas of 500-900 m ² / g
• C) pore volumes of 0.4 to 1.0 cm ³ / g
• D) thermal stability in the sense that X-ray Guinier recordings up to 1000 ° C no diffraction reflexes Have stable aluminum oxide phases detected.

The new mesoporous aluminum oxides with a high degree Structuredness can be used as catalysts, catalyst carriers ger or adsorbents are used.

The MESOX process according to the invention for the manufacture of Position of the new aluminum oxides is based on the structure a hydrolyzed by controlled water addition, monomeric aluminum compound with the addition of a PRZ in one non-aqueous solvents. The structuring is done by Condensation reactions caused by the PRZ to become non-lamellar Guide alumina with uniform mesopores.

In particular, the MESOX process according to the invention for the production of mesoporous aluminum oxides is characterized in that a monomeric aluminum alkoxide is produced by controlled addition of water in the presence of a pore-regulating additive (PRZ)

• a) an equimolar mixture of one or more saturated or unsaturated mono- or dicarboxylic acids having 5 to 21 carbon atoms and one or more tertiary amines of the formula (I)
  NR ² R ³ R ⁴ (I)
  wherein R ² , R ³ and R ^{4 may be the} same or different and are C ₁ -C ₂₀ alkyl and C ₁ -C ₁₀ hydroxyalkyl, or
• b) of alkylammonium salts of the general formula (II)
  R ¹ COO ^- [HNR ² R ³ R ⁴ ] ⁺ (II)
  wherein R ^{1 is} an alkyl radical or a saturated or unsaturated carboxylic acid radical each having 5 to 21 carbon atoms, and R ² , R ³ and R ⁴ have the meaning given above,
  in a non-aqueous solvent at temperatures from room temperature to 100 ° C for a period of 1 to 60 minutes, the precipitated and separated product is dried and the pore-regulating additive is removed.

Under the term "controlled water addition" is ver stood that for the hydrolysis of the monomeric aluminum compound the necessary amount in succession without substantial excess to dissolve the PRZ before the subsequent addition of the monomers Aluminum compound is given, or the synthesis mixture (Solution of the PRZ + monomeric aluminum compound) via the ge entire precipitation and structuring period with a water vapor-saturated atmosphere is brought into contact.

Alkoxides are used as monomers of aluminum. For the complete hydrolysis of the monomeric aluminum alkoxide, three times the molar amount of water is required in accordance with equation (I)

Al (OR) ₃ + 3 H ₂ O → Al (OH) ₃ + 3 ROH (1)

(R = -CH ₃ CH ₂ CH (CH ₃ ), -C (CH ₃ ) ₃ or -CH (CH ₃ ) ₂ ).

Since water is formed during the condensation of the aluminum hydroxide, e.g. B. according to equations (2) and (3)

Al (OH) ₃ → AlOOH + H ₂ O (2)

2Al (OH) ₃ → Al ₂ O ₃ + 3H ₂ O (3)

is the minimum amount of water required for condensation at only 1.5-2.0 moles of water / mole of aluminum alkoxide.

Polar aprotic compounds such as z. B. dimethyl sulfoxide (DMSo) and N, N-dimethylformamide (DMF). The PRZ consists of the above components, the alkyl radical R ² , R ³ or R ⁴ z. B. -C ₂ H ₅ or z. B. -C ₂ H ₄ OH can be. The PRZ solution can also be prepared in situ by adding the two individual components.

The share of the PRZ in the synthesis mixture is 1-10  Mol.%, Based on the aluminum alkoxide, preferably 2-3 mol.%. The molar ratio of the amount of water added to the aluminum niumalkoxide is 1-10, preferably 3-6. The cheapest the hydrolysis proceeds at a molar ratio of 5. The Precipitation and structuring takes place under normal pressure in the room temperature.

Further advantageous embodiments are in the claims Chen 4 to 13 listed.

The MESOX method according to the invention already takes place when stirring the Al alcoholate into the solution of the PRZ The precipitation and structuring of the aluminum at room temperature oxides with the mesoporosity detectable in the product. It has proved to be cheap, the amount of water needed already before adding the Al alkoxide to the solution of the PRZ. After finally stirring in the solution of the monomeric aluminum niumalkoxids hydrolysis and condensation run off Formation of Al-O-Al bonds simultaneously.

After stirring for 30 minutes at room temperature, the reaction is practically complete. A hydrothermal synthesis step at higher temperatures is not necessary and rather harmful. The MESOX process according to the invention thus has the advantage over the previously known processes that the production of a mesoporous aluminum oxide is possible with little expenditure of time and energy. The products are characterized by the following properties

• - The carboxylic acid / amine mixture used as PRZ can by calcining in air at 550 ° C within 2 h remove completely,
• - The mesoporous aluminum oxides show after drying and Calcine uniform mesopores with a medium Diameter of 2-5 nm,
• - they have BET surface areas of 500-900 m ² / g,
• - They show no reflections of crystalline Al ₂ O ₃ phases in X-ray Guinier images up to a temperature of 1000 ° C, neither intermediate nor at 1000 ° C. Diffraction reflections of α-Al ₂ O ₃ can only be recognized after cooling to room temperature.

The characterization of the textural properties was carried out by nitrogen adsorption, by measuring the adsorbed N ₂ volume V _ads as a function of the partial pressure of nitrogen in equilibrium with the sample kept at 77 K.

The surface can be obtained from the straight line obtained by plotting the measured values V _ads against the relative pressure p / p ₀

(C is a specific constant and V _{m is} the volume of the monolayer coverage by the adsorbate) according to the BET theory (Brunauer, S., Emmett, PH, Teller, EJ Am. Chem. Soc. 60 (1938) 309) .

Materials are classified as microporous, meso porous and macroporous according to the IUPAC standard according to the following diameters:
microporous: pore diameter <2.0 nm
mesoporous: 2.0 ≦ d ≦ 50 nm
macroporous <50 nm

Pore distribution and sizes are determined from the adsorption or desorption isotherms using a pore model calculated.

An analytical relationship between the pore radius (or diameter) and the adsorbed amount of V _{ads is} necessary for the calculation, a _distinction having to be made between micro and mesopores.

Due to the type of adsorption, there are different filling mechanisms for the pores. When a certain pressure is exceeded, micropores fill up spontaneously (capillary condensation). An adsorbate layer initially builds up in mesopores, the thickness of which depends on the pressure. Only when a critical free core diameter (a pore assumed to be cylindrical) has been reached does capillary condensation occur at the next pressure increment. A distinction must be made between the actual pore radius R and the meniscus radius r _k . The difference corresponds to the adsorbate thickness. In the mesopore range, the free core radius r _{k is represented} as a function of the relative pressure by the Kelvin equation:

RT ln (p / p ₀ ) = - 2 γ V _mol cos Θ / r _k ,

where γ corresponds to the surface tension of the adsorbate, V _mol , which represents the molar volume and Θ is the contact angle (for practical reasons, the latter is mainly assumed to be zero). The concept of capillary condensation was confirmed up to r _k = 2.0 nm; for radii in the order of 1.5 nm, the uncorrected Kelvin equation gives a value that is about 30% too low. At r _k = 1.0 (d _k = 2.0 nm) the absolute lower validity limit is reached. Theoretically, there is no upper validity limit. However, since for a capillary condensation in pores with radii around 80 nm the absolute pressure must already be approx. 99% of the saturation vapor pressure, an upper limit is reached from a technical point of view at approx. 40 nm radius (80 nm diameter). This is followed by methodical high-pressure mercury porosimetry for pore characterization in the macroporous range.

From the adsorption data, the Kel vin equation to calculate pore distributions. The individual ver driving differ essentially only in terms of Assumption of a specific pore model for calculating the ver division and in the prescribed use of the Adsorption or desorption branch of the isotherm for the Be bills.

The Bestim measurement of the pore size distribution according to the Barrett Joyner-Halenda (BJH) (Barrett, E.P., Joyner, L. S. and Halenda, P.P., J. Am. Chem. Soc. 73 (1951) 373-380).  

The results are shown in the coordinates dV / dR and R. The size dV / dR is the derivation of the normalized N ₂ volume according to the pore radius of the adsorbent.

The invention is illustrated by the examples below explained in more detail. Show in the accompanying drawings

Fig. 1 diagram for the textural characterization by N ₂ adsorption: (device ASAP 2000 from Micromeritics).

Fig. 2 diagram of the pore radius distribution, derived from the N ₂ adsorption isotherms by the method of Barrett-Joy ner-Halenda (BJH).

Fig. 3 TEM image of the aluminum oxide synthesized according to Example 1.

Fig. 4 solid-state NMR spectrum of the product according to Example 1, annealed at 550 ° C.

example 1

1.0 g of surfactant (2.3 mmol, equimolar mixture of oleic acid [cis-octa-dec-9-ene acid, C ₁₇ H ₃₃ COOH] and triethanolamine) are added as PRZ at room temperature with stirring (2000 min ^-1 ) 100 ml of DMSO dissolved and stirred for 10 min. 24.6 g of aluminum tri-sec-butoxide, Al (OC ₄ H ₉ ) ₃ (100 mmol) are also added to this solution at room temperature and with stirring (500-1000 min ^-1 ). After 5 min, 9.0 g of water (500 mmol) are added dropwise with stirring (500-1000 min ^-1 ). A colorless, coarse precipitate is formed. The solution is heated to 80 ° C. with stirring (500-1000 min ^-1 ) for 30 min. After the solution has cooled, the precipitate is filtered off with suction and washed three times with 50 ml of ethanol each (technical, approx. 5% water content). Drying takes place first at room temperature in an air stream, then in a drying cabinet at 130 ° C. The dry precipitate (approx. 11.0 g coarse powder) can easily be crushed in the grater. Remnants of the PRZ are removed by baking in an air stream (at 5 K / min to 550 ° C, then 1 h 550 ° C). After this treatment, the product is pure white.

The shape of the adsorption isotherms corresponds to type IV according to the Brunauer classification and is characteristic of mesoporous solids. The BET surface area, derived from the N ₂ adsorption isotherm shown in Figure 1, has a value of 701 m ² / g. The Al ₂ O ₃ according to the invention has a mean pore diameter of 2.4 nm (2.4 nm = 24 angstroms) ( Figure 2), and the pore volume of the material is 0.53 cm ³ / g, derived from the cumulative pore volumes of the Pores between 0.45 and 150 nm radius according to the BJH approach.

After the thermal removal of the PRZ (this is done by heating in an air stream at 550 ° C.), the regular structure shown in FIG. 3 is present in the product according to the invention. The ²⁷ Al solid = NMR reveals aluminum with coordination 4 (chemical shift 64.672 ppm), 5 (33.601 ppm) and 6 (9.795 ppm) ( Fig. 4). The mesoporous material has a high proportion of octadedrally coordinated aluminum, as is characteristic of amorphous Al ₂ O ₃ phases.

Example 2

The synthesis is carried out analogously to Example 1. In contrast to Example 1 is not the condensation by dropping reached by water but in a modified way. The Lö solution that already contains surfactant and aluminum tri-sec-butoxide holds, is in a closable bowl made of glass or poly propylene (about 10-15 cm in diameter). In this bowl becomes a smaller bowl (approx. 3-5 cm in diameter) with approx. 20 g water and closed the arrangement. The condens sation takes place through the water vapor present in the gas space, approx. 1-2 vol.% at room temperature. The insertion of the condensate tion with the formation of a fine precipitate is on the cloudiness of the solution can be seen. The condensation is finished when the entire solution has become opaque. The Wei The processing is carried out analogously to example 1.

The BET surface area of the product obtained is 933 m ² / g. The average pore diameter is 2.4 nm, the pore volume is 0.51 cm ³ / g.

Example 3

At room temperature, with stirring (2000 min ^-1 ), 0.67 g of surfactant (2.3 mmol, equimolar mixture of caprylic acid [octanoic acid, C ₇ H ₁₅ COOH] and triethanolamine) as PRZ are dissolved in 100 ml of DMSO and stirred for a further 10 min . 24.6 g of aluminum tri-sec-butoxide, Al (OC ₄ H ₉ ) ₃ , (100 mmol) are also added to this solution at room temperature and with stirring (500-1000 min ^-1 ). After 5 min, 9.0 g of water (500 mmol), dissolved in 9 g of DMSO, are added dropwise with stirring (500-1000 min ^-1 ). A colorless, coarse precipitate is formed. The solution is heated to 80 ° C. with stirring (500-1000 min ^-1 ) for 30 min. After the solution has cooled, the precipitate is filtered off and washed three times with 50 ml of ethanol (technical, approx. 5% water content). Drying takes place first at room temperature in an air stream, then in a drying cabinet at 130 ° C. The dry precipitate (approx. 11.0 g coarse powder) can be easily crushed in the grater. The PRZ is removed by baking in an air stream (at 5 K / min to 550 ° C, then 1 h 550 ° C). After this treatment, the product is pure white.

The BET surface area is 755 m ² / g. The mean pore diameter is 1.8 nm, the pore volume is 0.42 cm ³ / g.

Example 4

At room temperature, while stirring (2000 min ^-1 ), 1.0 g of surfactant (2.3 mmol, equimolar mixture of behenic acid [docosanic acid, C ₂₁ H ₄₃ COOH] and triethanolamine) is dissolved in 100 ml of DMSO as a PRZ and stirred for a further 10 min . 24.6 g of aluminum tri-sec-butoxide, Al (OC ₄ H ₉ ) ₃ , (100 mmol) are also added to this solution at room temperature and with stirring (500-1000 min ^-1 ). After 5 min, 9.0 g of water (500 mmol) are added dropwise with stirring (500-1000 min ^-1 ). A colorless, coarse precipitate is formed. The solution is heated to 80 ° C. with stirring (500-1000 min ^-1 ) for 30 min. After the solution has cooled, the precipitate is filtered off with suction and washed 3 times with 50 ml of ethanol each (technical, approx. 5% water content). Drying takes place first at room temperature in an air stream, then in a drying cabinet at 130 ° C. The dry precipitate (approx. 11.0 g coarse powder) can be easily crushed in the grater. Remnants of the PRZ are removed by heating in an air stream (at 5 K / min to 550 ° C, then 1 h 550 ° C). After this treatment, the mesoporous aluminum oxide is pure white.

The BET surface area is 821 m ² / g. The mean pore diameter is 3.8 nm, the pore volume is 0.55 cm ³ / g.

Claims (14)

1. Mesoporous aluminum oxides, characterized by

• 1. uniform mesopores with a minimum diameter of 1 nm and an average diameter of 2-5 nm
• 2. BET surface areas of 500-900 m ² / g
• 3. Pore volumes of 0.4 to 1.0 cm ³ / g
• 4. Thermal stability in the sense that no diffraction reflections of crystalline aluminum oxide phases can be detected in X-ray Guinier recordings up to 1000 ° C.

2. Mesoporous aluminum oxides, characterized by

• 1. uniform mesopores with a minimum diameter of 1 nm and an average diameter of 2-5 nm
• 2. BET surface areas of 500-900 m ² / g
• 3. Pore volumes from 0.4 to 1.0 cm '/ g
• 4. thermal stability in the sense that no diffraction reflections of crystalline aluminum oxide phases can be detected in Roentgen Guinier recordings up to 1000 ° C. and produced by controlled addition of water to a monomeric aluminum alkoxide in the presence of a pore-regulating additive
  • a) an equimolar mixture of one or more, saturated or unsaturated mono- or dicarboxylic acids having 5 to 21 carbon atoms and one or more tertiary amines of the formula
    NR ² R ³ R ⁴ (I)
    wherein R ² , R ³ and R ^{4 may be the} same or different and are C ₁ -C ₂₀ alkyl and C ₁ -C ₁₀ hydroxyalkyl, or
  • b) of alkylammonium salts of the general formula
    R ¹ COO ^- [HNR ² R ³ R ⁴ ] ⁺ (II)
    wherein R ^{1 is} an alkyl radical or a saturated or unsaturated carboxylic acid radical each having 5 to 20 carbon atoms, and R ² , R ³ and R ^{4 have} the meaning given above,
  in a non-aqueous solvent at temperatures from room temperature to 100 ° C for a period of 1 to 60 minutes, drying the precipitated and separated product and removing the pore-regulating additive.

3. Process for the preparation of mesoporous aluminum oxides, characterized in that a monomeric aluminum alkoxide by controlled addition of water in the presence of a pore regulating the addition

• a) an equimolar mixture of one or more saturated or unsaturated mono- or dicarboxylic acids having 5 to 21 carbon atoms and one or more tertiary amines of the formula (I)
  NR ² R ³ R ⁴ (I)
  wherein R ² , R ³ and R ^{4 may be the} same or different and are C ₁ -C ₂₀ alkyl and C ₁ -C ₁₀ hydroxyalkyl, or
• b) of alkylammonium salts of the general formula (II)
  R ¹ COO ^- [HNR ² R ³ R ⁴ ] ⁺ (II)
  wherein R ^{1 is} an alkyl radical or a saturated or unsaturated carboxylic acid radical each having 5 to 21 carbon atoms, and R ² , R ³ and R ⁴ have the meaning given above,

is precipitated in a non-aqueous solvent at temperatures from room temperature to 100 ° C. for a period of 1 to 60 minutes, the precipitated and separated product is dried and the pore-regulating additive is removed. 4. The method according to claim 3, characterized in that R ² , R ³ and R ^{4 are} each an alkyl radical having 1 to 10 carbon atoms, preferably an ethyl radical (-C ₂ H ₅ ). 5. The method according to claim 3, characterized in that the hydroxyalkyl radical is hydroxyethyl (-C ₂ H ₄ OH). 6. The method according to claim 3, characterized in that as monomeric aluminum compound used an aluminum alkoxide  is selected from aluminum-tri-sec-butoxide, aluminum tri-tert-butoxide or aluminum iso-propoxide, preferably aluminum nium-tri-sec-butoxide. 7. The method according to claim 3 (a) or 3 (b), characterized in that as the carboxylic acid cis-octadec-9-ene acid (C ₁₇ H ₃₃ COOH), octanoic acid (C ₇ H ₁₅ COOH) or docosanoic acid (C ₂₁ H ₄₃ COOH) and as amine triethanolamine is used in equimolar amounts as a pore-regulating additive or the respective compound of formula (II) with the corresponding radicals. 8. The method according to claim 3, characterized in that a technical mixture of decanoic acid (C ₁₀ ), lauric acid (C ₁₂ ), myristic acid (C ₁₄ ), palmitic acid (C ₁₆ ), oleic acid (C ₁₈ ), stearic acid (C) as the carboxylic acid ₁₈ ) and arachidic acid (C ₂₀ ) and as amine triethanolamine in equimolar amounts as pore regulating the additive is used. 9. The method according to any one of claims 3-8, characterized records that as a non-aqueous solvent dimethyl sulfoxide is used. 10. The method according to any one of claims 3-9, characterized records that as a non-aqueous solvent N, N-dimethylfor mamid is used. 11. The method according to any one of claims 3-10, characterized records that a proportion of pore-regulating addition of 1-10 Mol.%, Preferably 2-3 mol.%, Based on the aluminum alkoxide, is added. 12. The method according to any one of claims 3-11, characterized records that the for the hydrolysis of the monomeric aluminum alk amount of water required before the Alumi is added nium alkoxide to the solution of the pore-regulating additive is set and this amount 1-10 mol%, preferably 3-6 mol%,  and most preferably 5 mol%, based on the aluminum alkoxide. 13. The method according to any one of claims 1-12, characterized records that the precipitation and structuring of the mesoporous Alumina only through contact with the water free synthesis mixture with water vapor in the closed or open system by passing a water vapor saturated Air flow takes place over the liquid synthesis mixture. 14. The method according to claim 3, characterized in that controlled water addition at room temperature he follows.