Catalyst support coating slurry and coatings

Claim 1

A ceramic support coating slurry resistant to gel formation and adapted to form a porous, substantially uniform, thermally durable and adherent coating on a refractory ceramic substrate, consisting essentially of very fine grained gamma alumina having a size not larger than about 200 A in the amount of about 5 to 70 weight percent of the solids and one of the active alumina precursors consisting of alpha alumina monohydrate and pseudoboehmite in the amount of about 30 to 95 weight percent of the solids, said alumina and precursor being suspended in sufficient deionized water to form a slurry having the desired application characteristics, said solids being present in an amount of about 30-36% by weight of said slurry, said gamma alumina serving to disperse said precursor without the need for peptizing agents and functioning as a binder to give coherence within the coating and adherence to the substrate.

Claim 11

A method for applying a porous, substantially uniform, thermally durable and adherent coating to a refractory ceramic or metallized ceramic support comprising the steps of making an aqueous, non-thixotropic homogeneous suspension consisting essentially of from about 5 to 70 weight percent of the solids of a very fine grained gamma alumina having a size not larger than about 200 A and from about 30 to 95 weight percent of one of the active alumina precursors consisting of alpha alumina monohydrate and pseudoboehmite in sufficient deionized water to form the desired application characteristics, applying said suspension to the surfaces of said support, drying said coated support followed by calcining at a temperature of from about 500° to 800° C. so as to drive off structural water of hydration and thus activate the precursor material by forming the gamma or eta alumina, said very fine grained gamma alumina serving to disperse said precursor without the need for peptizing agents and functioning as a binder to give coherence within the coating and adherence to the support, and said solids comprising about 30-36% by weight of said suspension.

Claim 12

A method for applying a porous, substantially uniform, thermally durable and adherent coating to a refractory ceramic or metallized ceramic support comprising the steps of making an aqueous, non-thixotropic homogeneous suspension consisting essentially of from about 5 to 70 weight percent of the solids of a very fine grained gamma alumina having a size not larger than about 200 A and from about 30 to 95 weight percent of one of the active alumina precursors consisting of alpha alumina monohydrate and pseudoboehmite in sufficient deionized water to form the desired application characteristics, applying said suspension to the surfaces of said support, drying said coated support followed by calcining at a temperature of from about 500° to 800° C. so as to drive off structural water of hydration and thus activate the precursor material by forming the gamma or eta alumina, said very fine grained gamma alumina serving to disperse said precursor without the need for peptizing agents and functioning as a binder to give coherence within the coating and adherence to the support, and said solids comprising about 30-36% by weight of said suspension.