CATALYST FOR BREAKING DOWN HYDROCARBONS, AND FUEL CELL SYSTEM

An object of the present invention is to provide a nickel-containing catalyst having a strong correlation between a carrier and nickel, which is excellent in anti-coking property and is optimum for DSS operation, and a fuel cell system. The catalyst for decomposing hydrocarbons according to the present invention comprises a compound comprising at least nickel and aluminum, and metallic nickel having a particle diameter of 1 to 25 nm, in which bond energies between the metallic nickel and the compound comprising at least nickel and aluminum in the catalyst are 874.5 to 871.5 eV (Ni 2p), 857 to 853 eV (Ni 2p) and 73.5 to 70 eV (Al 2p), and an activation energy of the catalyst is 4 x 10to 5 x 10J/mol.