Process for producing porous spinel materials

Claim 1

A method for preparing porous bodies consisting essentially of spinel and/or crystals isostructural with spinel having an average pore size between about 450-700 A, about 80% of said pores being within about ±25% of the average pore size, and having a surface area between about 10-75 meters 2 /gram, said crystals having the general formula AO.B 2 O 3 wherein A represents a divalent metal ion and B represents a trivalent metal ion, which comprises the steps of: (a) impregnating a porous, trivalent metal ion-containing material having a surface area between about 50-500 meters 2 /gram, said trivalent metal ion being selected from the group of Al +3 , Fe +3 , and Cr +3 , with a solution of a divalent metal ion-containing compound, said divalent metal ion being selected from the group of Mg +2 , Fe +2 , Mn +2 , and Zn +2 , which compound, upon pyrolysis, will be converted to the respective oxide or other compound capable of reacting with said trivalent metal ion-containing material, said divalent metal ion-containing compound being present in a quantity sufficient to produce an amount of the corresponding divalent metal oxide or other compound ranging from about, by weight, 5% below to about 10% above that required to stoichiometrically react with said trivalent metal ion-containing material; (b) drying the impregnated material; and (c) firing the dried material at a temperature of at least 800° C., but not higher than about 1250° C., for a period of time sufficient to cause essentially complete reaction between said trivalent metal ion-containing material and said divalent metal ion-containing material to form spinel and/or crystals isostructural with spinel.

Claim 2

A method for preparing porous bodies consisting essentially of spinel and/or crystals isostructural with spinel having an average pore size between about 450-700 A, about 80% of said pores being within about ±25% of the average pore size, and having a surface area between about 10-75 meters 2 /gram, said crystals having the general formula AO.B 2 O 3 wherein A represents a divalent metal ion and B represents a trivalent metal ion, which comprises the steps of: (a) impregnating a porous, trivalent metal ion-containing material having a surface area between about 50-500 meters 2 /gram, said trivalent metal ion being selected from the group of Al +3 , Fe +3 , and Cr +3 , with a solution of a divalent metal ion-containing compound, said divalent metal ion being selected from the group of Mg +2 , Fe +2 , Mn +2 , and Zn +2 , which compound, upon pyrolysis, will be converted to the respective oxide or other compound capable of reacting with said trivalent metal ion-containing material, said divalent metal ion-containing compound being present in a quantity sufficient to produce an amount of the corresponding divalent metal oxide or other compound ranging from about, by weight, 5% below to about 10% above that required to stoichiometrically react with said trivalent metal ion-containing material; (b) drying the impregnated material; and (c) firing the dried material at a temperature of at least 800° C., but not higher than about 1250° C., for a period of time sufficient to cause essentially complete reaction between said trivalent metal ion-containing material and said divalent metal ion-containing material to form spinel and/or crystals isostructural with spinel.