Effect of preparation methods on structure and performance of Ni/Ce_(0.75)Zr_(0.25)O_2 catalysts for CH_4-CO_2 reforming

摘要

The impregnated Ni/Ce_(0.75)Zr_(0.25)O_2 catalysts were prepared with the supports synthesized by the co-precipitation involving the surfactant or not, and the co-precipitated Ni/Ce_(0.75)Zr_(0.25)O_2 catalysts were also prepared with or without the surfactant assistance. In the co-precipitated catalysts, Ni~(2+) entered the lattice of Ce_(0.75)Zr_(0.25)O_2 solid solution, which led to a better nickel dispersion and a stronger interaction between nickel species and the solid solution in comparison with the impregnated catalysts. With the surfactant assistance, the catalysts had larger surface area and pore volume than the ones without the surfactant. Among the prepared catalysts, the co-precipitated one with the surfactant assistance showed the highest activity in CH_4-CO_2 reforming. Under the conditions of 0.1 MPa, 1123 K, n_(CH_4)_(CO_2) = 1 and space velocity of 1.2 × 10~4 h~(-1) the CH_4 and CO_2 conversions were about 92% and 94% over the catalyst, respectively. It is revealed that the catalysts performance is related to the textural properties, the support activity, and the nickel dispersion and the interaction between nickel species and the support.