SHAPED POROUS BODIES OF ALPHA-ALUMINA AND METHODS FOR THE PREPARATION THEREOF
First Claim
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1. A method for making a shaped porous body comprising interlocking alpha-alumina platelets, the method comprising:
- a. providing a vessel in which a total pressure can be varied and controlled;
b. introducing into the vessel a shaped precursor body which comprises at least one alpha-alumina precursor;
c. introducing into the vessel, as a fluorine-containing gas at the conditions of introduction, a fluorine-containing compound;
d. establishing a total pressure within the vessel of between about 1 torr and 100,000 torr; and
e. contacting the introduced fluorine-containing compound with at least a portion of the shaped precursor body, at one or more temperatures, for one or more pressures, for one or more time periods, sufficient to convert at least 50% of the alpha-alumina precursor to alpha-alumina platelets.
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Abstract
This invention relates to shaped porous bodies of alpha-alumina platelets which are useful as catalyst carriers, filters, membrane reactors, and preformed bodies for composites. This invention also relates to processes of making such shaped bodies and processes for modifying the surface composition of alpha-alumina.
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Citations
51 Claims
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1. A method for making a shaped porous body comprising interlocking alpha-alumina platelets, the method comprising:
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a. providing a vessel in which a total pressure can be varied and controlled; b. introducing into the vessel a shaped precursor body which comprises at least one alpha-alumina precursor; c. introducing into the vessel, as a fluorine-containing gas at the conditions of introduction, a fluorine-containing compound; d. establishing a total pressure within the vessel of between about 1 torr and 100,000 torr; and e. contacting the introduced fluorine-containing compound with at least a portion of the shaped precursor body, at one or more temperatures, for one or more pressures, for one or more time periods, sufficient to convert at least 50% of the alpha-alumina precursor to alpha-alumina platelets. - View Dependent Claims (5, 14, 15, 17, 45, 48, 49, 50)
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2. A method for making a shaped porous body comprising interlocking alpha-alumina platelets, the method comprising:
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a. providing a vessel; b. introducing into the vessel a shaped precursor body which comprises at least one alpha-alumina precursor; c. heating the vessel to a temperature above 700°
C.;d. introducing into the heated vessel, as a fluorine-containing gas at the conditions of introduction, a fluorine-containing compound; and e. contacting the introduced fluorine-containing compound with at least a portion of the shaped precursor body, at least one temperature above 700°
C., for one or more time periods, sufficient to convert at least 50% of the alpha-alumina precursor to alpha-alumina platelets.
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3. A method for making a shaped porous body comprising interlocking alpha-alumina platelets, the method comprising:
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a. providing a vessel; b. introducing into the vessel a shaped precursor body which comprises at least one alpha-alumina precursor; c. introducing into the vessel, as a fluorine-containing gas at the conditions of introduction, a fluorine-containing compound not consisting essentially of hydrogen fluoride, selected from the group consisting of (1) fluororocarbons, SiF4, BF3, NF3, F2, XeF2, SF6, PF5, CF4, CHF3, C2H2F4, and AlF3, (2) mixtures of two or more of these gases, and (3) mixtures of HF and one or more of fluororocarbons, SiF4, BF3, NF3, F2, XeF2, SF6, PF5, CF4, CHF3, C2H2F4, and AlF3; and d. contacting the introduced fluorine-containing compound with at least a portion of the shaped precursor body, at one or more temperatures, and for one or more time periods, sufficient to convert at least 50% of the alpha-alumina precursor to alpha-alumina platelets. - View Dependent Claims (16)
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4. A method for modifying the surface composition of alpha-alumina comprising:
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a. providing a vessel; b. introducing into the vessel alpha-alumina having a surface composition; c. introducing into the vessel, as a fluorine-containing gas at the conditions of introduction, a fluorine-containing compound; and d. contacting the introduced fluorine-containing compound with at least a portion of the alpha-alumina for one or more periods of time, and at one or more temperatures sufficient to modify the surface composition of the alpha-alumina. - View Dependent Claims (43, 44)
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6. A carrier for a catalyst for the epoxidation of an olefin wherein the carrier:
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(a) comprises at least 80 percent by weight alumina, and of that alumina, at least 90 percent is alpha-alumina, exclusive of modifier; (b) has a surface area of at least 1.0 m2/g; (c) has a porosity of at least 75 percent; and
an average flat plate crush strength of at least 1 lb/mm (0.45 kg/mm), measured as a hollow cylinder having an axial cylindrical opening the length of the cylinder, an O.D. of 0.26 inches (6.60 mm) and an I.D. of the opening of 0.1 inches (2.54 mm) and a length of 0.25 inches (6.35 mm).
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7. A carrier for a catalyst for the epoxidation of an olefin wherein the carrier:
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(a) comprises at least 80 percent by weight alumina, and of that alumina, at least 90 percent is alpha-alumina, exclusive of modifier; (b) has a surface area of at least 1.0 m2/g; (c) has a porosity of at least 70 percent and an average flat plate crush strength of at least 3.5 lb/mm (1.6 kg/mm), measured as a hollow cylinder having an axial cylindrical opening the length of the cylinder, an O.D. of 0.26 inches and an I.D. of the opening of 0.1 inches and a length of 0.25 inches.
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8. Interlocking alpha-alumina platelets comprising a surface composition comprising silicon-containing species with a concentration of about 1 to about 20 atom percent silicon as measured by x-ray photo-electron spectroscopy.
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9. Interlocking alpha-alumina platelets comprising a surface composition comprising boron-containing species with a concentration of about 1 to about 20 atom percent boron as measured by x-ray photo-electron spectroscopy.
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10-13. -13. (canceled)
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18-42. -42. (canceled)
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46-47. -47. (canceled)
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51-52. -52. (canceled)
Specification