关键词: adsorption, methane, carbon dioxide, reforming, nickel catalyst, pulse reaction, carbon species

Abstract: The adsorption and dissociation of methane and carbon dioxide for reforming on nickel catalysts were extensively investigated by TPSR, TPD, XPS and pulse reaction methods. These studies showed that the decomposition of methane results in the formation of at least three kinds of surface carbon species on supported nickel catalysts. Carbidic Ca, carbonaceous Cb and carbidic clusters Cr surface carbon species formed by the decomposition of methane demonstrated dierent surface mobility, thermal stability and reactivity. Carbidic Ca is a very active and important intermediate in carbon dioxide reforming with methane, and the carbidic clusters Cr species might be the precursor of surface carbon deposition. The partially dehydrogenated Cb species can react with H2 or CO2 to form CH4 or CO. On the other hand, it was proven that CO2 can be weakly adsorbed on supported nickel catalysts, and only one kind of CO2 adsorption state is formed. The interaction mechanism between the species dissociated from CH4 and CO2 during reforming was then hypothesized.

Key words: adsorption, methane, carbon dioxide, reforming, nickel catalyst, pulse reaction, carbon species