DE2826095C2 - Process for the production of granulated active clay - Google Patents

Description

The invention relates to a method for Production of granulated active alumina in which aluminum trihydroxide is heated, rehydrated with water. Shaped into granules, dried at a temperature of 20 to 150'C and then heated is annealed at a temperature of 400 to 600 ° C.

If the aluminum trihydroxide is heated at temperatures of 1300 to 1400 "C according to the process known for example from DE-AS 12 80 231 or US Pat. ρ "AI2O) is, as is clear from the X-ray structure analysis such 95%." χ "-" ρ "AIjOj containing product has after rehydration of 8 hours at a temperature of 60 to 8O ⁰ C still 46 to 76%" χ «- » ρ «AIjOi on.

The invention has for its object a process for the production of granulated active To indicate alumina, which makes it possible, when heated, to obtain a completely X-ray amorphous product, which when interacting with water practically completely in the desired modification of the aluminum hydroxide passes and is obtained in the granulated active clay which is in the phase composition is completely homogeneous.

This is achieved according to the invention in a method of the type mentioned at the outset by adding the aluminum trihydroxide by contact in the fluidized bed of a solid heat transfer medium which has a temperature of 350 to 600 ^° C. for a contact time of 0.05 to 0.5 s Amorphous aluminum oxide converts that the amorphous product obtained is mixed with water up to a concentration of 100 to 500 g / l, converted to aluminum oxide and the hydration at a temperature of 20 to 100 ° C and a pH of 5 to 12 for 0.5 to 10 hours, a rehydrated product containing pseudo-boehmite, bayerite or north strandite is obtained .-%, converted to Na ₃ O, washes that the product is then washed at a temperature of 20 to 150 ^° C. with an acid, the water-soluble base able to form aluminum salts, treated.

The process according to the invention for the production of granulated active alumina thus consists in Decomposition of the aluminum trihydroxide when it comes into contact with the layer of a solid heat carrier, which has a temperature of 350 to 600 ° C, with a contact time of 0.05 to Op s.

For example, metallic ceramic particles of any shape are used as solid heat transfer media. Such a decomposition of the aluminum trihydroxide gives an X-ray amorphous decomposition product with losses on ignition of 10 to 16 percent by weight, which belongs to the amorphous aluminum trihydroxide, which in its composition is close to the monohydrate of aluminum oxide. The term "ignition losses" means a standard weight loss obtained when the product is heated at a temperature of 800 ^° C. for 2 hours. The sedimentation analysis of amorphous aluminum trihydroxide, which is a decomposition product of aluminum trihydroxide, and the starting aluminum trihydroxide showed that the particle size distribution is the same. This means that the decomposition does not result in any destruction of the particles of the starting aluminum trihydroxide, but rather only their bursting with precipitation / white water molecules. As a result, the specific surface area of the decomposition product increases significantly. which in some cases reaches a size of 400 m-Vg.

The product obtained from the decomposition of the aluminum trihydroxide is mixed with water until a suspension with a concentration of 100 to 500 g / l is obtained. converted to AI ₂ Oi, and hydrated. Depending on the hydration conditions (the temperature and pH of the medium), the amorphous aluminum oxide is the product of the decomposition of the aluminum trihydroxide. capable of various modifications of aluminum trihydroxide. namely to convert into pseudoboehmite aluminum trihydroxide, bayerite aluminum trihydroxide and north strandite aluminum trihydroxide or a mixture thereof. In order to obtain pseudo-boehmite, aluminum trihydroxide, passing the hydration of the decomposition product in the aqueous medium with a pH value of 5 to 10 at a temperature of 20 to 8O ⁰ C. It should be noted that upon mixing and further hydration of the amorphous alumina that is a product of the decomposition of the aluminum trihydroxide. with water there is a pin increase in the pH of the medium to 10.5 to 11 due to the precipitation of the sodium iodine from the particles of the decomposition product into the water. Therefore, to achieve a pH value of less than 11, acid is added to the mixture of the decomposition product and the water in an amount of from 1 to 8 g of acid per 1 kg of aluminum oxide.

During the hydration of the decomposition product of the aluminum trihydroxide to form the bayerite or of north strafidite aluminum trihydroxide

it is not necessary to adjust the pH value with acid. In this case, passing the hydration of amorphous alumina, which is a decomposition product of aluminum trihydroxide, at a temperature of 90 to 100 ⁰ C and a pH of from 10.5 to 11 for the preparation of bayerite AIuminiumtrihydroxid or at a temperature of 80 to 90 ° C and a pH value of 11 to 12 in the medium of 5% ethylenediamine for the production of Nordstrandit aluminum trioxide.

In order to obtain active alumina free from nairium admixtures, the hydrated decomposition product of aluminum trihydroxide is filtered and washed with water before the acid treatment is carried out, the remaining sodium admixture content of the precipitate being converted to 0.05 to 0.17 percent by weight after the filtration before purification Na ₂ O is. In order to obtain a purer active clay, converted to sodium, the hydrated decomposition product, the aluminum trihydroxide, is washed. with distilled water with a total consumption of 7 to 9 liters of water per 1 kg of aluminum oxide in the precipitate.

The hydrated decomposition products of the aluminum trihydroxide are also treated an acid, the water-soluble basic aluminum salts able to form, for example with nitric acid, up to the achievement of plastic masses of aluminum trihydroxide, which can be shaped into granules in a manner known per se.

The formed granules are dried at a temperature of 20 to 150 ⁰ C and annealed at a temperature of 400 to 600'C in the flow of dry air or inert gas, with a consumption of air of at least 1000 St 'from.

This gives granulated active alumina with a specific surface area of 200 to 400 m ² / g, a total pore volume of 0.45 to 0.90 cmVg and a different porous structure.

Compared to the above-mentioned known method, the method according to the invention has for Production of granulated active alumina has a number of significant advantages.

Carrying out the process of decomposition of the aluminum trihydroxide upon contact of the same with the Fluidized bed of a solid heat carrier makes it possible to heat and mass transfer in the To intensify the decomposition zone, which in turn makes it possible to lower the decomposition temperature below markedly shortening the residence time of the aluminum trihydroxide particles in the high temperature zone.

It is not absolutely necessary to carry out the decomposition of the aluminum trihydroxide up to the formation of transition aluminum oxides of the 2-Al ₂ Oj and Q-Al ₂ Oj types with losses on ignition of 5 to 10 percent by weight. The process according to the invention gives an X-ray amorphous decomposition product with losses on ignition of 10 to 16 percent by weight, that is to say amorphous aluminum trihydroxide, the composition of which is close to aluminum monohydroxide. The properties of such a decomposition product practically do not differ from the properties of the transition aluminum oxides of the type X ^ Al ₂ O ₃ and O'Ai ₂ O ₃ . Carrying out the decomposition of the aluminum trihydroxide by the process according to the invention makes it possible to retain a water molecule in the structure of the decomposition product, which leads to a significant reduction in the heat required for the decomposition, because the heat required for the removal of the last, the third water molecule (35, 3 kcal / mol) the sum of the heat for the removal of the first two water molecules (363 kcal / mol) is practically the same.

In addition, it makes the change in the conditions of hydration (temperature, pH of the medium and duration) of the decomposition product of aluminum trihydroxide in water in the form of a suspension with a -T concentration of 100 to 500 g / l, converted to Al ₂ Oj, or Changing the acid treatment conditions of the hydrated decomposition product makes it possible to make a broad modification of the porous structure of the end product, the granulated active clay.

The acid treatment of the hydrated decomposition products makes it possible to produce plastic masses of To obtain aluminum trihydroxides which are formed into granules by any known method can.

The following examples serve to provide a better understanding of the present invention.

B e i s ρ i e 1 1

A mixture consisting of aluminum trihydroxide with a particle size of at most 200 μίτι and air is passed through a Rt iktor with a fluidized bed of a solid heat carrier in the form of cylindrical aluminum granules 4 mm in diameter and 4 mm in length. The fluidized bed of the solid heat transfer medium has a temperature of 500 ^° C. and a height in the steady state of 60 mm. The mean contact time of the aluminum trihydroxide particles with the hot solid heat carrier is 0.1 second. During this time, the aluminum trihydroxide decomposes with the formation of amorphous aluminum oxide with a specific surface area of 250 mVg and losses on ignition of 14 percent by weight. The X-ray phase analysis of this decomposition product shows that the Ze is ^r reduction product X-ray amorphous.

1 kg of the decomposition product is mixed with 3 liters of distilled water by making a suspension with a concentration of 215 g / l. converted to Al ₂ Oj. receives. In order to adjust the pH to 8, 4.3 g of nitric acid are added to the suspension. The decomposition product is hydrated at a temperature of 70 ° C. for 6 hours with constant stirring. This gives you a

decomposition product thus hydrated with a moisture wedge in the pressed state of 60%. The specific surface area of the hydrated product dried at a temperature of 110 ^ C is! 240 m ² / g. The X-ray phase analysis gives the following composition: 75 percent by weight pseudoboehmite aluminum trihydroxide, 30 percent by weight bayerite aluminum trihydroxide.

After hydration, the hydrated decomposition product is filtered off and washed with 7 liters of distilled H ₂ O per 1 kg of Al ₂ Oj in the precipitate, a residual Na content in the precipitate of 0.02 percent by weight, converted to Na ₂ O, being achieved.

2j1 kg of the hydrated decomposition product mixed with 2.2 liters of distilled water until a suspension with a concentration of 250 g / l is obtained, converted to Al ₂ O ₃ , and treated with nitric acid in an amount of 0.15 mol of HNO ₃ 1 mole of Al ₂ O ₃ each. The treatment is at one temperature

carried out at 130 ¹¹ C for 4 hours with constant stirring, with πνη a plastic, non-segregating mass of aluminum trihydroxide obtained.

The mass obtained by the acid treatment of aluminum trihydroxide is formed into spherical granules, which can then anneal at a temperature of 1C5 ° C dried and in an oven at a temperature of 550 ⁰ C during 4 hours at an air flow rate of 1000 St '.

The end product, the granulated active clay, is spherical granules with a diameter of 2.5 ± 0.5 mm with the following characteristics: specific surface 35Om-Vg, total volume 0.71 cmVg, predominant pore radius 60 Å, compressive strength 95 kp / cm ² .

Example 2

A mixture consisting of aluminum trihydroxide with a particle size of at most 200 μm and air is passed through a reactor with a fluidized bed of a solid heat carrier in the form of ceramic balls 2 to 3 mm in diameter. The fluidized bed of the solid heat transfer medium has a temperature of 350 ^° C. and a height in the steady state of 100 mm. The mean contact time of the aluminum trihydroxide particles with the hot solid heat carrier is 0.2 seconds. During this time, the aluminum trihydroxide decomposes with the formation of amorphous aluminine oxide with a specific surface area of 200 m ² / g and ignition losses of 16 percent by weight. The X-ray phase analysis of this decomposition product shows that the decomposition product is X-ray amorphous with traces of residual aluminum trihydroxide.

1 kg of the decomposition product is mixed with 1.4 liters of distilled water by making a suspension with a concentration of 350 g / l. converted to AIjOj. In order to maintain a pH value of 9.5, 2.5 g of nitric acid are added to the suspension. The decomposition product is hydrated at a temperature of 80.degree. C. for 5 hours with constant stirring, a hydrated decomposition product having a compressed moisture of 48 percent by weight being obtained. The specific surface area of the ^{hydrated product dried at a temperature of 110 °} C. is 220 m −1 / g. The X-ray phase analysis gives the following composition; 60 percent by weight pscdoboehmite aluminum trihydroxide and 40 percent by weight bayerite aluminum trihydroxide.

The suspension of the hydrated decomposition product is then treated with a concentration of 350 g / l. converted to AbOj, with hydrochloric acid in an amount of 0.20 mol HCl per 1 mol AbOj. The treatment is carried out at a temperature of 150 ^° C. for 6 hours with constant stirring, a plastic mass of aluminum trihydroxide being obtained. The resulting mass action by the Säurebe is formed into cylindrical granules, dried at a temperature of 20 ° C for 24 hours and then at a temperature of 150 "C" for 1 hour and annealed in an oven at a temperature of 400 ⁰ C while 6 hours in the air stream.

The end product, the granulated active clay, is cylindrical granules with a diameter of 4 mm and a length of 4 to 6 mm with the following characteristics; specific surface 300 cm, total pore volume 0.45 cm, predominant pore radius 50 Å, face compressive strength 140 kp / cm ² ,

Example 3

A mixture consisting of aluminum hydroxide with a particle size of at most 200 μm and air is passed through a reactor with a fluidized bed of a solid heat transfer medium in the form of copper cylinders 2 mm in diameter and 2 mm in length. The fluidized bed of the solid heat carrier has a temperature of 600 ° C and a height in the steady state of 40 mm. The mean contact time of the particles of aluminum trihydroxide with the hot heat transfer medium is 0.05 seconds, during which the trihydroxide decomposes until an X-ray amorphous decomposition product is formed with a specific surface area of 380 m ² / g and ignition losses of 15 percent by weight.

1 kg of the decomposition product of the aluminum trihydroxide is mixed with 7.5 liters of distilled water, a suspension with a concentration of 100 g / l, converted to AI., Oj, being obtained. To .inzuhalten a pH of 10, are added to the suspension 0.85 g of nitric acid zv The hydration of the decomposition product is carried out at a temperature of 50 ⁰ C for 8 hours under constant stirring by, wherein one solid hydrated decomposition product having a moisture obtained in the pressed state of 55 percent by weight. The specific surface area of the hydrated product dried at a temperature of 110 ° C. is 300 m ² / g. The X-ray phase analyst; results in d .; the following composition: 60 percent by weight of pseudoboehmite aluminum trihydroxide. 40 weight percent bayerite aluminum trihydroxide.

The suspension of the hydrated decomposition product is then treated with a concentration of 100 g / l, converted to AIjOj, with nitric acid in an amount of 0.1 mol of HNO ₁ per 1 mol of AIjO ₁ . The treatment is carried out at a temperature of 110 ^° C. for 6 hours with constant stirring. The mass of the aluminum trihydroxide obtained by the acid treatment formed jn π into granules, dried at a temperature of 100 ° C and annealed at a temperature of 400 ° C for 4 hours in an air stream ^r a ..

The granulated active clay obtained is spherical granules 0.1 to 2 mm in diameter with the following characteristics: specific surface area 380 m ² lg, total pore volume 0.65 cm / g. predominant pore radii between 150 Å and 1000 Å.

Example 4

F.in mixture consisting of Alumini'imtrihydroxid μίτι having a particle size of at most 200 and air, guide 'it through a reactor with a fluidized bed with a solid heat carrier consisting of ring-shaped granules of' consists mm inner diameter and i mm outside diameter. The layer of solid heat carrier has a temperature of 450 "C and a height of 300 mm. The residence time of the

ho aluminum trihydric oxide particles in the layer of the hot Heat transfer medium is 0.5 seconds. During this time the aluminum hydride decomposes xids up to the formation of a x-ray amöff> heh product with a specific surface of 400 mVg and

b5 glow losses of 10 percent by weight,

1 kg of the decomposition product is mixed with 0.8 liters of distilled water, a suspension with a concentration of 500 c / \, tim <

₁ , get. To adjust the pH to 8, 4.5 g of nitric acid are added to the suspension. The hydration of the Zerselzungsproduktes is carried out at a temperature of 6O ⁰ C for 8 hours under constant stirring, yielding a decomposition product having a moisture hydratisierles in the pressed condition of 43 weight percent. The specific surface area of the dried at a temperature of 11O ⁰ C the hydrated product is 230 MVG. The X-ray phase analysis shows the following composition: 80 percent by weight of pseudoboehmil aluminum irhydroxide. 20 weight percent bayerite aluminum trihydroxide.

After hydration, the suspension is filtered and the precipitate obtained is washed with 7 liters of HjO per 1 kg of Al ₂ Oj in the precipitate, with a residual sodium content in the precipitate of 0.015 percent by weight, converted to Na2O.

1.6 kg of the washed precipitate is mixed with 2 liters of distilled water until a suspension with a concentration of 350 g / l is obtained. converted to AbOj and treated analogously to Example 2 with acid. The mass of the aluminum hydroxide obtained by the acid treatment, formed into ring-shaped granules, dried at a temperature of 100 "C and annealed at a temperature of 550 ⁰ C for 4 hours in an air stream, with a consumption of 1000 St. from ^1.

The granulated active clay obtained is annular granules of 4 mm in outer diameter.

2 mm inside diameter and 4 to 8 mm length with the following parameters: specific surface 270 m ² / g, total pore volume 0.5 cmVg, predominant pore radius 100 Å. Front compressive strength 40 kp / cm- '.

Example 5

An an.iio. / u Seispiel 3 obtained plastic mass of the MIM u.jmtrihydroxids be formed after the acid treatment to microspheroidal granules, dried at a temperature of 100 ⁰ C and annealed at a temperature of 400 ^r C for 4 hours in an air stream.

The granulated active clay obtained is spherical granules from 20 to 100 μm in diameter with the following characteristics: specific surface area 330 m ² / g. Total pore volume 0.6 mVg, predominantly pore radii between 100 Å and 700 to 1000 Å.

Example 6

2.1 kg of washed hydrated decomposition product, obtained analogously to Example 1. mixed with

03 liters of distilled water and treated with nitric acid in an amount of 0.08 mol of HNO ₃ per 1 mol of Al ₂ Oj. The treatment is carried out at a temperature of 20 ^° C. for 3.5 hours with constant stirring ° C and anneals at a temperature of 550 ⁰ C for 5 hours in a stream of air at a flow rate of 1000 St ^-1 .

The granulated active alumina obtained has the following characteristics: specific surface area 350 m ² / g, total ^{pore volume 0.75 cm 3} / g, predominant pore radii between 100 Å and 10,000 Å, face compressive strength 80 kp / cm ² .

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Example 7

I kg of the decomposition product of aluminum trihydroxide, obtained analogously to Example 1, are mixed with 7.6 liters of distilled water and hyclralisiert at a temperature of 90 ° C for 10 hours constant stirring. It becomes a medium with a pH value of 11 due to the excretion of sodium ions from the particles of the decomposition product into the water

to generated. This gives a hydrated decomposition product with a moisture content in the pressed state of 45 percent by weight. The specific The surface of the hydrated product dried at a temperature of 110 ° C is 60 m 2 / g.

The X-ray phase analysis gives the following composition: 90 percent by weight of bayerite aluminum trihydroxide and 10 weight percent pseudoboehmite aluminum trihydroxide.

The hydrated decomposition product is then filtered off and washes with 9 liters per I kg of AbOi im Precipitation, with a residual sodium content in the precipitate of 0.02 percent by weight, converted on NajO, receives.

1.6 kg of the washed, hydrated decomposition product is mixed with 1.4 liters of distilled water and treated with nitric acid in an amount of 0.05 Mtfl HNOi per 1 mol Al ₂ O ₁ . The treatment is carried out at a temperature of 90.degree. C. for 4 hours with constant rippling. The durcn the acid treatment obtained plastic mass of aluminum trihydroxide is formed into cylindrical granules of 5 mm in diameter and 4 to 5 mm in length, dried at a temperature of 100 ⁰ C and annealed at a temperature of 450 ° C during

Ji 5 hours in a stream of air at one flow rate from 1000 pcs.

The granulated active clay obtained has the following characteristics: specific surface area 330 m ² / g. Total pore: iv volume 0.90 cm Vg. Predominant pore

• »n radii between less than 40 Ä and 300 A. Face compressive strength 50 kp / cm- '.

Example 8

1 kg of the decomposition obtained analogously to Example 4

4Ί product of aluminum trihydroxide is mixed with 8 liters of distilled water and hydrated at a temperature of 100 ° C for 10 hours constant stirring. The pH value is determined by the excretion of sodium ions from the decomposition

> o product into the water on 10.5. This gives a hydrated decomposition product with a moisture content in the pressed state of 40 percent by weight. The specific surface area of the dried at a temperature of 110 ⁰ C hydrated Prcluktes is 90 m ² / g.

The X-ray phase analysis shows the following composition: 70 percent by weight of bayerite aluminum trihydroxide and 20 percent by weight of nordstrandite aluminum hydroxide and 10 percent by weight of pseudoböh-

so with aluminum trihydroxide.

The hydrated decomposition product is washed free of the sodium additions analogously to Example 7.

1.5 kg of the washed hydrated decomposition product of aluminum trihydroxide is mixed with 1.2 liters of distilled water and treated with Nitric acid in an amount of 0.1 MoI HNO3 per 1 MoI A12O3- The treatment is carried out at one temperature

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carried out from 110 ⁰ C for 6 hours with constant stirring. The further processing of the plastic mass obtained by the acid treatment is carried out analogously to Example 7.

This gives granulated active alumina with the following characteristics: specific surface area 390 m ² / g, total pore volume 0.8 cm-Vg, predominant pore radii between 50 Å and 10,000 Å, face pressure 50 kp / cm ² .

Example 9

1 kg of the decomposition product of aluminum trihydroxide obtained analogously to Example 3 is mixed with 7.5 liters of 5% aqueous ethylenediamine solution. the pH of the mixture reaching 12. The hydration ion of the decomposition product is at a Temperature of 90 'C "carried out for 8 hours with constant stirring, one hydrated decomposition product with a moist

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receives. The specific surface area of the hydrated product, dried at a temperature of 110 ° C., is 60 m ² / g. The X-ray phase analysis gives the following composition: 90 percent by weight of Nordstrandite aluminum trihydroxide and 10 percent by weight of pseudoboehmite aluminum trihydroxide. The further treatment of the hydrated decomposition product obtained is analogous to Example 7. This gives granulated active alumina with the following characteristics: specific surface area 350 m ² / g, total pore volume 0.75 cmVg, predominant pore radii between 50 A and 5000 A, face compressive strength 60 kp / cm ² .

Example 10

A mixture consisting of aluminum trihydroxide with a particle size of at most 200 μm and air is passed through a reactor with a fluidized bed of a solid heat carrier made of annular granules of 2 mm inside diameter and 4 mm outside diameter. The layer of the solid heat carrier has a temperature of 550 ^° C. and a height of 200 mm. The residence time of the aluminum trihydroxide particles in the layer of the hot heat transfer medium is 035 seconds. During this time, the aluminum trihydroxide decomposes until an X-ray amorphous product is formed with a specific surface area of 300 m ² / g and ignition losses of 12 percent by weight.

1 kg of the decomposition product is mixed with 7.8 liters of distilled water to obtain a suspension with a concentration of 100 g / l, converted to Al2O3. To adjust the pH to 5, 7 g of nitric acid are added to the suspension. The hydration of the Zersetzüngsproduktes one leads through at a temperature of 20 ⁰ C for 8 hours under constant stirring to obtain a hydrated decomposition product having a moisture in the compressed state of 55 weight percent. The specific surface area of the hydrated product dried ^{at a temperature of ItO 0 C is}

ί 210m ² / g. The X-ray phase analysis gives the following composition: 70 percent by weight psudoboehmite aluminum trihydroxide, 30 percent by weight Bayefil aluminum irihydroxide and 18 percent by weight hydrargillite.

in the hamlet processing of the hydrated decomposition product takes place according to Example 3. The properties of the end product correspond to those of the Example 3.

Example 11

1 kg of the decomposition product, obtained analogously to Example 1. is mixed with 2.5 liters of distilled water by adding a suspension with a concentration of 240 g / l. converted to AI2O). In order to set a value of 5.8 to <? Inpn, 6.5 g of nitric acid are added to the suspension. The hydration of the Zerselzungsproduktes is carried out at a temperature of 2O ⁰ C for 0.5 hours under continuous intensive stirring. Thereby, a hydrated decomposition product having a compressed moisture content of 60% is obtained. The specific surface area of the hydrated decomposition product, dried at a temperature of 110 ° C., is 320 m ² / g. The X-ray phase analysis shows

jo following composition: 70% pseudoboehmite aluminum trihydroxide and 30% by weight of amorphous aluminum trihydroxide (decomposition product of aluminum trihydroxide).

After hydration, the hydrated decomposition product is filtered off and washed with 7.5 liters per 1 kg AI2O3 in the precipitate, with a residual content of Sodium in the precipitate of 0.02 percent by weight, converted to NajO, is obtained.

2.1 kg of the hydrated decomposition product are mixed with 2 liters of distilled water until a suspension with a concentration of 260 g / l is obtained. converted to AI2O3, and treated unit nitric acid in an amount of 0.1 mol HNO3 per 1 mol AI2O3. The treatment is carried out at a temperature of 130 ^° C. for 4 hours with constant stirring, a plastic mass of aluminum trihydroxide being obtained as a result.

The mass obtained by the acid treatment of aluminum trihydroxide is formed into spherical granules, which are then annealed at 100 ⁰ C and dried at 500 ⁰ C for 4 hours at e.ner air flow rate of 1000 St ".

The end product, granulated active clay, is spherical granules 2.5 ± 0.5 mm in diameter

55, with the following characteristics ^; Specific surface area 320 mVg, total pore volume Ö £ 5 criP / g, predominant pore radii 50 A, compressive strength 100 kp / cm ² .

Claims (1)

Claim: Process for the production of granulated active alumina, in which aluminum trihydroicide is heated, rehydratisierl with water, shaped into granules, ^{dried at a temperature of 20 to 150 3} C and then calcined by heating at a temperature of 400 to 600 ° C, characterized that the aluminum trihydroxide is converted into amorphous aluminum oxide by contact in the fluidized bed of a solid heat transfer medium which has a temperature of 350 to 600 ^° C. for a contact time of 0.05 to 0.5 s, that the amorphous product obtained is reacted with water up to a concentration of 100 to 500 g / l, converted to aluminum oxide, mixed and the hydration is carried out at a temperature of 20 to 100 ⁰ C and a pH of 5 to 12 for 0.5 to 10 h, one Rehydrated product with a content of pseudoboehmite, bayerite or nordstrandite is obtained that, if necessary, the rehydrated product after separating off the water with water up to Achievement of a sodium content in this of at most 0.02 wt .-%, converted to Na.jO, ^ ₅ washes, that the product is then vt to form the water-soluble basic aluminum salts ^{at a temperature of 20 to 150 0 C with an acid} rmag, treated. 30th