Methods and apparatuses for regenerating catalysts and methods of inhibiting corrosion in catalyst regenerating apparatuses are provided. An exemplary apparatus includes: a metal vessel configured to receive a spent catalyst stream and contact at least a portion of the spent catalyst stream with an oxygen containing environment at a sufficiently high temperature to burn coke present in the spent catalyst stream; a refractory material overlying at least a portion of an inner surface of the metal vessel; and a corrosion inhibiting material in contact with at least a portion of the inner surface of the metal vessel and disposed between the inner surface and at least a portion of the refractory material, wherein the corrosion inhibiting material is heat stable at a temperature of at least up to about 400° F. (about 204° C.) and inhibits contact of an acid environment with the inner surface of the metal vessel.