Ni-Cu/samaria-doped ceria catalysts for steam reforming of methane in the presence of carbon dioxide

A series of samaria-doped ceria (SDC) supported Ni-Cu catalysts have been employed to carry out steam reforming of methane at 673–823 K without or in the presence of carbon dioxide. Results show that hydrogen can be produced from H 2O dissociation over SDC and SDC supported Ni and Cu catalysts. The activity of H 2O dissociation over Cu is higher than that over Ni. Carbon dioxide (CO 2) has the ability to oxidize various Ni-Cu/SDC catalysts. The order of CO 2 dissociation reactivity over various Ni-Cu/SDC catalysts is the same as that of steam reforming of methane with or without the presence of carbon dioxide. Ni–Cu interaction enhances the activity of steam reforming of methane. Cu enhances the water–gas shift activity in the presence of CO 2 and this enhancement effect may be quantitatively related to the amount of the Cu–Ni species. The methane conversion rate of steam reforming increases as the CO 2 content in the feed increases. With increasing CO 2 content, H 2O conversion rate decreases but hydrogen (H 2) production rate increases in CO 2-steam reforming; in addition, the net CO 2 production rate decreases but the carbon production rate increases quite extensively. The presence of CO 2 thus requires special attention to the problem of carbon deposition during internal reforming of methane.