Appeal No. 94-3243
Application 07/974,560
slurry of a precursor boehmite alumina prior to aging the
resulting mixture at a particular pH and a particular temperature
for the purposes of converting a substantial portion of the
alumina into a colloidal sol. See the specification, page 3.
According to examples I and II at pages 4 through 6 of the
specification, adding the particular stabilizer prior to, rather
than after, the formation of the colloidal sol allows retention
of a large surface area at high temperatures with a lesser amount
of the particular stabilizer.
Claim 1 is representative of the subject matter on appeal
and reads as follows:
1. A process for preparing a stabilized alumina comprising:
forming an aqueous slurry of a precursor boehmite alumina;
admixing said aqueous slurry with from about 0.5 to about
20% by weight calculated as metal oxide based on the Al O
2 3
content of said stabilized alumina of a stabilizer selected from
the group consisting of water-soluble salts of polyvalent metal
cations of Groups IIA and IIIB of the periodic table, oxides of
metals of Groups IIA and IIIB of the periodic table, compounds
containing metals from Groups IIA and IIIB of the periodic table
that hydrolyze in aqueous solutions of produce water-soluble
salts of polyvalent metal cations and/or oxides of metals in
Groups IIA and IIIB of the periodic table, and mixtures thereof;
aging said alumina slurry containing said stabilizer at a pH
of from about 3 to about 9 and at a temperature greater than
about 70 C for a period of time sufficient to convert the greater0
portion of said alumina to a colloidal sol of boehmite alumina
containing said stabilizer;
2
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