TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: In the method: the reforming of low-sulfur-content hydrocarbon fuel is performed after the reforming of high-sulfur content hydrocarbon fuel, where reforming of the low-sulfur-content hydrocarbon fuel is performed both before and after the reforming of the high-sulfur content hydrocarbon fuel. The method further comprises: providing a carrier for the catalyst; and activating the catalyst by heating the catalyst in hydrogen and/or another reducing gas. In the system, the catalyst is configured for steam reforming with the hydrocarbon fuel having a sulfur content of greater than 0.1 parts per million by volume for a period of not less than 30 hours, where the catalyst is configured for self cleaning of sulfur compounds when performing steam reforming using a hydrocarbon fuel having little or no sulfur content, and the little or no sulfur content is less than 0.05 parts per million by volume. The catalyst is configured for self cleaning within a period of less than or equal to 50 hours, preferably less than or equal to 25 hours to achieve a methane conversion of greater than 90% of the equilibrium conversion when using natural gas as a hydrocarbon feed stream. The catalytic reactor is configured to steam reform the hydrocarbon fuel with or without an oxidant. In the fuel cell system: the reformer is configured to reform a high-sulfur content hydrocarbon fuel with at least steam for a first period of time, and reform a low-sulfur-content hydrocarbon fuel with at least steam for a second period of time; and the catalytic reactor is configured to self-clean sulfur poisoning during the second period of time, where the second period of time is less than an amount of time required for a catalyst having a catalytically active material containing essentially of ruthenium to self-clean. Preferred Components: the platinum content is a minimum platinum content consistent with the desired level of sulfur resistance. The ruthenium content of the catalytically active materials is 75-99.99 wt.%; and the platinum content of the catalytically active materials is 0.01-25 wt.%. The carrier includes a refractory oxide including at least one of silica, alumina, zirconia or tungsten oxides, where the carrier includes mixed refractory oxides having at least two cations. The alumina oxide is stabilized by at least one of baria, ceria, lanthanum oxide or magnesia. The catalyst and the carrier do not include alkali metals or their oxides. In the system: the ruthenium content of the catalyst is greater than the platinum content of the catalyst; and the catalyst is supported on a carrier that includes alumina oxide. The sulfur content is greater than 0.1 ppm/volume, preferably greater than 0.5 ppm/volume.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The system further comprises a fuel cell in fluid communication with the catalytic reactor. The catalytic reactor includes a tube having an axis, and many channels extending parallel to the axis, where the catalyst is disposed in the surfaces of the channels, and the number of channels is 200-1200 channels per square inch when viewed in a direction along the axis. EXAMPLE - No suitable example given.