Process of preparing high purity alumina bodies
AssigneeUnion Carbide Corporation
InventorsWillis W. Weber, Joseph A. Herbst
Life of this patent
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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.
Claims23
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;
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- (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.
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.
Dependencies are inferred from the claim text.