TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The catalyst support comprises the alkaline-earth metal hexaaluminate in an amount of greater than or equal to 98 vol.%. The alkaline-earth metal hexaaluminate comprises at least one alkaline-earth metal selected from calcium (Ca), strontium (Sr) and barium (Ba); or BaO6Al2O3. The inert gas is helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) or N2. The atmosphere contains at least 50 vol.% of N2. The at least one precursor oxide comprises a member selected from alkaline-earth metal oxides. Preferred Method: The heating is performed at a total pressure of 1 atm or at a total pressure of less than 1 atm or at a total pressure of greater than 1 atm. The precursor oxides are heated in an atmosphere containing a partial pressure of O2 of less than or equal to 0.10 atm. The heating is at a temperature of not greater than 1100 (preferably not greater than 950, especially not greater than 800) degrees C. The method further involves heating the at least one precursor oxide in another atmosphere having a partial pressure of O2 greater than 0.20 atm. The other atmosphere is air; and the total pressure in the other atmosphere is 1 atm. The heating in the atmosphere having a partial pressure of O2 of less than or equal to 0.20 atm and the heating in the other atmosphere having a partial pressure of O2 greater than 0.20 atm are each repeated more than once. EXAMPLE - A catalyst was prepared by impregnating about 1 wt.% iridium (Ir) onto a mixed calcium aluminate/alumina support. The metal was deposited from an aqueous solution of hexachloroiridic acid onto a commercially available calcium aluminate/alumina support. After the support was impregnated with the metal-containing solution, the catalyst was dried at 110 degrees C for 24 hours and then calcined in air at about 500 degrees C. The catalyst was divided into two approximately equal portions. The first portion of the catalyst was placed in a reactor that operated continuously at about 750 degrees C for over 500 hours on a hydrocarbon feed that contained sulfur and O2. The second portion of the catalyst was placed in a reactor that was started up and allowed to run at 750 degrees C for about 24 hours on the same hydrocarbon/sulfur/O2 feed as was used for the first portion. The reactor was shut down and purged with air. The reactor was then reheated to 750 degrees C and purged with steam prior to the next 24 hour feedstock-charged cycle. These steps were repeated for over 500 hours of total operating time. The cycling conditions were representative of the environments to which the catalyst was exposed with normal reactor start-ups and shut-downs. The catalyst exhibited acceptable catalytic activity both in a reactor operated with air cycling and in a reactor operated without air cycling.