# US 4,379,134 A · Process of preparing high purity alumina bodies

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- Number: US 4,379,134 A
- Document ID: US4379134A
- Status: Granted
- Kind: A
- Application number: 06/347,336
- Filed: 1982-02-11
- Granted: 1983-04-05
- Earliest claimed: 1981-02-13
- Assignees: Union Carbide Corporation
- Inventors: Willis W. Weber; Joseph A. Herbst
- Web page: https://patentgrep.com/patent/US4379134A

## CPC

- B01J 21/04: Alumina
- C01F 7/021: After-treatment of oxides or hydroxides
- C01P 2006/12: Surface area
- C01P 2006/16: Pore diameter
- C01P 2006/17: Pore diameter distribution
- C01P 2006/80: Compositional purity
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00})
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

High purity alpha-alumina bodies useful as catalyst supports are made by peptizing boehmite alumina in an acidic mixture containing fluoride anions, extruding the peptized alumina into shaped bodies and drying and calcining the bodies. The alpha-alumina bodies are characterized by a narrow pore-size distribution, having 85 percent of the total pore volume comprising pores of a diameter of from 10,000 to 200,000 Angstroms and by a surface area of less than one square meter per gram.

## Claims

### Claim 1

A process for the production of alpha-alumina bodies which comprises:
(i) blending a peptizing acid, water and fluoride anions with alumina, said peptizing acid and water being of a sufficient amount to form an extrudable mixture, and said extrudable mixture containing an effective amount of fluoride anions to form the alpha-alumina bodies;
(ii) extruding said extrudable mixture to form shaped bodies;
(iii) calcining said bodies at a temperature from about 400.degree. C. to about 700.degree. C. for a sufficient duration to convert the alumina of said bodies to a gamma-alumina phase; and
(iv) calcining said bodies in the gamma-alumina phase at a temperature from about 1200.degree. C. to about 1700.degree. C. for a sufficient duration to convert essentially all the gamma-alumina of said bodies to an alpha-alumina phase, said alpha-alumina bodies characterized by having at least 85 percent of the pore volume being represented by pores having a diameter of form 10,000 to 200,000 Angstroms and having a square area less than one square meter per gram.

### Claim 2 (depends on 1)

The process of claim 1 wherein the source of said fluoride anions is one or more from the group consisting of NaF, LiF, CsF, PbF.sub.2, KF, (NH.sub.4)HF.sub.2, MgF.sub.2, BaF.sub.2, CrF.sub.2, TiF.sub.3, (NH.sub.4)F, FeF.sub.2, ZnF.sub.2, CuF.sub.2 and HF.

### Claim 3 (depends on 2)

The process of claim 2 wherein the source of said fluoride anions is hydrogen fluoride.

### Claim 4 (depends on 2, 3)

The process of claim 2 or claim 3 wherein the alumina is of the boehmite type.

### Claim 5 (depends on 4)

The process of claim 4 wherein said extrudable mixture contains from about 0.005 to about 0.50 grams of fluoride on a 100% HF basis per gram of anhydrous Al.sub.2 O.sub.3.

### Claim 6 (depends on 1)

The process of claim 1 further comprising drying the shaped bodies of step (ii) at a temperature from about 100.degree. C. to about 300.degree. C. to reduce the moisture content of the bodies to less than about 30 weight percent before step (iii).

### Claim 7 (depends on 5)

The process of claim 5 wherein the peptizing acid is a monofunctional aliphatic carboxylic acid containing from 1 to about 5 carbon atoms or a halogenated derivative thereof.

### Claim 8 (depends on 7)

The process of claim 7 wherein the peptizing acid is acetic acid.

### Claim 9 (depends on 6)

The process of claim 6 wherein the peptizing acid is nitric acid.

### Claim 10 (depends on 1)

The process of claim 1 wherein the calcining temperature of step (iv) is about 1200.degree. C. to about 1500.degree. C.

### Claim 11 (depends on 7)

The process of claim 7 further comprising blending carbonaceous burn out masses in step (i) to obtain alpha-alumina bodies in step (iv) characterized by having not greater than 10 percent of the pore volume being represented by pores having a diameter of from 200,000 to 1,000,000 Angstroms.

### Claim 12

A process for the production of alpha-alumina bodies which comprises:
(i) blending a peptizing acid, fluoride anions and water with alumina, said water and peptizing acid being of a sufficient amount to form a first extrudable mixture;
(ii) extruding said first extrudable mixture to form shaped bodies;
(iii) drying said bodies at a temperature from about 100.degree. C. to about 300.degree. C. to reduce the moisture content of said bodies to below 10 weight percent;
(iv) granulating and sizing said bodies to form a grain of from about 20 to 40 mesh U.S. Standard Sieve Screen;
(v) calcining the grain at a temperature from about 400.degree. C. to about 700.degree. C. for a sufficient duration to convert the alumina of said grain to a gamma-alumina phase;
(vi) blending said grain with a mixture comprising alumina, a peptizing acid and water, said water and peptizing acid being of a sufficient amount to form a second extrudable mixture, and said second extrudable mixture containing an effective amount of fluoride anions to form the alpha-alumina bodies;
(vii) extruding said second extrudable mixture to form shaped bodies;
(viii) drying said shaped bodies at a temperature from about 100.degree. l C. to about 300.degree. C. to reduce the moisture content to less than about 10 weight percent; and
(ix) calcining said shaped bodies at a temperature from about 1200.degree. C. to about 1700.degree. C. for a sufficient duration to convert essentially all the alumina of said bodies to an alpha-alumina phase, said alpha-alumina bodies characterized by having at least 85 percent of the pore volume being represented by pores having a diameter of from 10,000 to 200,000 Angstroms and having a surface area less than one square meter per gram.

### Claim 13 (depends on 12)

The process of claim 12 wherein the source of said flouride anions is one or more from the group consisting of NaF, LiF, CsF, PbF.sub.2, KF, (NH.sub.4)HF.sub.2, MgF.sub.2, BaF.sub.2, CrF.sub.2, TiF.sub.3, (NH.sub.4)F, FeF.sub.2, ZnF.sub.2, CuF.sub.2 and HF.

### Claim 14 (depends on 13)

The process of claim 13 wherein the source of said fluoride anions is hydrogen fluoride.

### Claim 15 (depends on 13, 14)

The process of claim 13 or claim 14 wherein the alumina is of the boehmite type.

### Claim 16 (depends on 15)

The process of claim 15 wherein the peptizing acid is nitric acid.

### Claim 17 (depends on 16)

The process of claim 16 wherein said second extrudable mixture contains from about 0.005 to about 0.50 grams of fluoride on a 100% HF basis per gram of anhydrous Al.sub.2 O.sub.3.

### Claim 18 (depends on 17)

The process of claim 17 further comprising blending carbonaceous burn-out masses in step (vi) to obtain alpha-alumina bodies in step (ix) characterized by having not greater than 10 percent of the pore volume being represented by pores having a diameter of from 200,000 to 1,000,000 Angstroms.

### Claim 19 (depends on 15)

The process of claim 15 wherein the peptizing acid is a monofunctional aliphatic carboxylic acid containing from 1 to about 5 carbon atoms or a halogenated derivative thereof.

### Claim 20 (depends on 19)

The process of claim 19 wherein the peptizing acid is acetic acid.

### Claim 21 (depends on 12)

The process of claim 12 further comprising calcining the shaped bodies of step (viii) at a temperature from about 400.degree. C. to about 700.degree. C. for a sufficient duration to convert the alumina of said bodies to a gamma-alumina phase before step (ix).

### Claim 22 (depends on 12)

The process of claim 12 wherein the calcining temperature of step (ix) is about 1200.degree. C. to about 1500.degree. C.

### Claim 23 (depends on 12)

The process of claim 12 wherein fluoride anions are added to step (vi).