Hydrogen and syngas production from two-step steam reforming of methane using CeO2 as oxygen carrier

CeO2 oxygen carrier was prepared by precipitation method and tested by two-step steam reforming of methane (SRM). Two-step SRM for hydrogen and syngas generation is investigated in a fixed-bed reactor. Methane is directly converted to syngas at a H-2/CO ratio close to 2 : 1 at a high temperature (above 750 degrees C) by the lattice oxygen of CeO2; methane cracking is found when the reduction degree of CeO2 was above 5.0% at 850 degrees C in methane isothermal reaction. CeO2-delta obtained from methane isothermal reaction can split water to generate CO-free hydrogen and renew its lattice oxygen at 700 degrees C; simultaneously, deposited carbon is selectively oxidized to CO2 by steam following the reaction (C+2H(2)O -> CO2+2H(2)). Slight deactivation in terms of amounts of desired products (syngas and hydrogen) is observed in ten repetitive two-step SRM process due to the carbon deposition on CeO2 surface as well as sintering of CeO2.