Systems and methods for steam reforming

1. A method for operating a fuel cell system, comprising:

providing a catalyst consisting essentially of platinum and ruthenium as catalytically active materials, wherein the platinum content by weight is selected based on a desired level of sulfur resistance and is less than the ruthenium content of the catalyst; and wherein the catalyst is configured for self cleaning of sulfur compounds when performing steam reforming using a low-sulfur content hydrocarbon fuel;

providing a catalytic reactor having surfaces having the catalyst disposed thereon and configured to expose the catalyst to at least a hydrocarbon fuel and steam;

reforming with the catalyst a high-sulfur-content hydrocarbon fuel with at least steam for a first period of time;

reforming with the catalyst a low-sulfur-content hydrocarbon fuel with at least steam for a second period of time whereby the catalyst, using the low-sulfur content hydrocarbon fuel, self-cleans of sulfur compounds that may be present from poisoning by sulfur exposure during the reforming of the high-sulfur-content hydrocarbon fuel; and

providing reformed hydrocarbon fuel to a fuel cell stack.

2. The method of claim 1 , wherein the reforming of the low-sulfur-content hydrocarbon fuel is performed after the reforming of the high-sulfur content hydrocarbon fuel.

3. The method of claim 2 , further comprising reforming the low-sulfur-content hydrocarbon fuel before the reforming of the high-sulfur content hydrocarbon fuel.

4. The method of claim 1 , wherein the platinum content is a minimum platinum content consistent with the desired level of sulfur resistance.

5. The method of claim 4 , wherein the ruthenium content of the catalytically active materials is selected to be approximately 75% to 99.99% by weight; and wherein the platinum content of the catalytically active materials is selected to be approximately 0.01% to 25% by weight.

6. The method of claim 1 , further comprising providing a carrier for the catalyst.

7. The method of claim 6 , wherein the carrier includes a refractory oxide, including at least one of silica, alumina, zirconia and tungsten oxides.

8. The method of claim 7 , wherein the carrier includes mixed refractory oxides having at least two cations.

9. The method of claim 7 , wherein the alumina oxide is stabilized by at least one of baria, ceria, lanthana and magnesia oxides.

10. The method of claim 1 , further comprising activating the catalyst by heating the catalyst in hydrogen and/or another reducing gas.

11. The method of claim 1 , wherein the providing of the catalyst includes providing at least some of the platinum and the ruthenium in the form of a platinum-ruthenium alloy.

12. A method for reforming a fuel, comprising:

providing a catalyst comprising platinum and ruthenium as catalytically active materials wherein the platinum content by weight is less than the ruthenium content; and wherein the catalyst is configured to desorb sulfur compounds when reforming a low-sulfur content fuel;

reforming with the catalyst a high-sulfur-content hydrocarbon fuel with at least steam;

reforming a low-sulfur-content fuel with the catalyst such that the catalyst, using the low-sulfur content fuel, desorbs sulfur compounds which may be bound to the catalyst that may be present from poisoning by sulfur exposure during the reforming of the high-sulfur-content hydrocarbon fuel.

13. The method of claim 12 , wherein the ruthenium content is approximately at least three times greater by weight than the platinum content.

14. The method of claim 13 , wherein the ruthenium content is approximately five times greater by weight than the platinum content.