Catalytic Steam Methane Reforming Over Ir/Ce0.9Gd0.1O2-x: Resistance to Coke Formation and Sulfur Poisoning
Résumé
This work investigates the catalytic properties of Ir/Ce0.9Gd0.1O2x (Ir/CGO) catalyst and CGO support in steam reforming of methane in the absence or presence of H2S (50?ppm) for further application in a solid oxide fuel cell (SOFC) working under methane at intermediate temperatures and integrating a gradual internal reforming concept. The catalytic activity was measured at 750 degrees C by using a 50?mol.% CH4/5?mol.% H2O/45?mol.% N2 mixture and a 10?mol.% CH4/90?mol.% N2 mixture. The addition of Ir to CGO improves the catalytic activity in hydrogen production by two orders of magnitude with respect to that of CGO alone. Temperature programmed oxidation experiments were performed after reaction in both types of mixtures to study the eventual formation of carbon deposits. Over Ir/CGO, carbon formed in little amounts (even in the absence of H2O in the feed), being highly reactive toward O2. Upon H2S addition, the CGO support exhibited surprisingly an improved catalytic activity on the contrary to Ir/CGO which partly deactivated. Upon suppression of H2S in the feed the initial catalytic activity was fully restored for both catalysts. The catalytic behavior of CGO in the presence of H2S was discussed, based upon temperature programmed reaction of CH4.