Abstract
Ceria promoted phosphate-zirconia supported nickel catalyst (10Ni1Ce/PZr; x = 0, 1, 1.5, 2, 2.5, 3, 5 wt%) are prepared and characterized by XRD, SEM, SEM-EDX, CH4-TPSR, NH3-TPD, cyclic H2TPR-CO2TPD-H2TPR, and TPH. Ceria addition induces surface reducibility, exposes reduced phases of NiO and Ni2P2O7 as CH4 decomposition sites, and persuades additional CO2 adsorbed species as formate species over the catalyst surface. It also switches mobile oxygen in the lattice and thereafter oxide vacancy is replenished by oxygen from CO2 to a great extent. Altogether, 1 wt% ceria loading (10Ni1Ce/PZr) ensures more than 90% H-2 yield (H-2/CO = 0.96) whereas 2 wt% ceria loading inputs constancy in catalytic performance up to 440 min TOS. Up to 3 wt% ceria loading, 97% hydrogen yield (H-2/CO similar to 1) is observed. Catalytic performance deteriorated above that 3 wt% ceria loading due to shading the catalytic active site or reoxidation of metallic nickel by excess ceria.