Transparent activated nonparticulate alumina and method of preparing same
AssigneeOwens-Illinois, Inc.
InventorBulent E. Yoldas
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Abstract
A transparent, activated, nonparticulate alumina with a total porosity of about 63% which consists of a unique pore morphology and size distribution and is thermally stable up to about 1,200.degree.C. at which temperature it can be nondestructively converted to alpha alumina is disclosed as well as a method of preparing said alumina by hydrolyzing aluminum alkoxides to form a particular sol which is essentially clear to the naked eye and the gel of which retains its integrity during drying and pyrolysis. The alumina thus produced is useful as a catalyst, absorbent and desiccant. In addition, a method of preparing the intermediate clear colloidal sol or gel consisting essentially of aluminum monohydrate is disclosed. This intermediate can be used to coat various substrates.
Claims18
A method for preparing a transparent, monolithic, nonparticulate, porous product consisting essentially of alumina with a total porosity of at least 50% which comprises the steps of:
- a. providing an acid peptized, clear colloidal solution by hydrolyzing an aluminum alkoxide of the formula Al(OR).sub.3, wherein R is an alkyl of 1-24 carbon atoms, with water, wherein the mole ratio of water to said alkoxide is at least 8:1 and wherein said acid peptization is effected with about 0.03 to about 0.250 moles of acid per mole of said alkoxide, said acid having an ionization constant of at least 1 .times. 10.sup..sup.-5 and having a noncomplexing anion with aluminum,
- b. gelling said clear solution, and
- c. drying said gel and pyrolyzing same by heating at a rate sufficiently slow to preclude cracking at a temperature in excess of about 500.degree. C. and for a time insufficient to form alpha Al.sub.2 O.sub.3 but sufficient to form said transparent, monolithic, porous, nonparticulate Al.sub.2 O.sub.3 product.
A method for preparing a transparent, monolithic, nonparticulate, porous product consisting essentially of Al.sub.2 O.sub.3 which comprises the steps of:
- a. providing a gel of the hydrolysis product obtained by hydrolyzing an aluminum alkoxide of the formula Al(OR).sub.3, wherein R is an alkyl of 1-24 carbon atoms, with water and an acid wherein the mole ratio of water to said alkoxide is in the range of 8:1 to 20:1 and wherein said acid is employed in an amount of about .03 to about .250 moles of acid per mole of said alkoxide, said acid having an ionization constant of at least 1 .times. 10.sup..sup.-5 and having a noncomplexing anion with aluminum,
- b. drying said gel, and
- c. pyrolyzing said gel by heating at a rate sufficiently slow to preclude cracking at a temperature in excess of about 500.degree. C. so as to form said transparent, monolithic, porous, nonparticulate Al.sub.2 O.sub.3 product, said heating being insufficient to form alpha alumina.
Dependencies are inferred from the claim text.