Effect of Ceria Doping in Different Impregnation Steps on Ni-Based Catalysts Loading on TiO2-SiC for CO Methanation

A series of TiO2-SiC supported Ni-based catalysts with and without ceria doping were prepared by a traditional impregnation method. CeO2 was introduced into the catalyst in different steps of the impregnation process. All the samples were characterized by N-2 physisorption, XRD, TPR, and TGA, and were tested for the performance of CO methanation in a fixed-bed reactor under atmospheric conditions through the steam of H-2/CO = 3 without diluent gas. All the Ni-based catalysts supported by TiO2-SiC exhibited the property of anti-sintering and could efficiently avoid carbon deposition occurring on catalysts. The experimental results show that the performance of all CeO2 doping samples (more than 80% of CO conversion) was better than the sample without CeO2 (around 20% of CO conversion). Introducing CeO2 after the dry step of impregnation achieved complete CO conversion at a lower temperature compared with its introduction through doping at the co-impregnation and step-impregnation methods. The results of further characterization indicate that the addition of CeO2 in different impregnation steps affected the dispersion of nickel on support, made the size of metal particles smaller, and changed the reducibility of catalysts.