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Abstract

Chemically and thermally stable monolithic catalysts are disclosed having platinum or alkali metal-vanadium active phases for use in the conversion of sulfur dioxide to sulfur trioxide. The platinum catalyst comprises a foraminous ceramic support which has at its wall surfaces a high surface area substrate for an active catalyst phase, and a combination of a platinum active phase and a promoter on the substrate. The substrate preferably comprises silica, provided, for example, by application of a silica washcoat. The promoter is selected from among compounds of zirconium, hafnium and titanium. The alkali-vanadium catalyst comprises a foraminous ceramic support having a porous silica substrate for the active phase at its foraminal wall surfaces. An alkali metal-vanadium active catalyst is in the pores of the porous silica. Methods for producing the catalysts of the invention are described, as is a method for producing sulfur trioxide with the platinum catalyst, in which the catalyst is regenerated with a mineral acid when activity has declined through aging or exposure to the conditions of the oxidation of sulfur dioxide.

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First Claim