Preparation of Ni-based catalysts by one step of calcination and reduction and its application in CH₄-CO₂ reforming reaction

The Ni/C-SiO₂ series catalysts were prepared by the method of soybean oil grinding, and were applied in the CH₄-CO₂ reforming reactions. These catalysts were characterized by the XRD, TG-DTG, BET, H₂-TPR, CO₂-TPD and chemical properties of the catalysts were measured by the fixed bed continuous reactions. The results showed that the nickel elements in the catalyst were fully transformed into Ni⁰ after calcining in inert atmosphere N₂ for catalyst precursor prepared by grinding method, thus realizing the preparation of the mesoporous Ni-based catalysts by one-step of the calcination and the reduction. There were two types of carbon on the catalyst after the CH₄-CO₂ reforming reactions, one was the residual carbon source in the prepared catalyst, and another causing catalyst deactivation was the carbon deposition produced in the process of the reforming reaction. The influences of the promoters, such as CeO₂, ZrO₂ and La₂O₃ on the catalyst properties were investigated. The results indicated that the particle diameter of the Ni⁰ in the Ni-CeO₂/C-SiO₂, Ni-ZrO₂/C-SiO₂ and Ni-La₂O₃/C-SiO₂ catalysts was decreased, the reaction activity of the Ni-CeO₂/C-SiO₂ and Ni-La₂O₃/C-SiO₂ catalysts was enhanced, and the carbon deposition on the Ni-ZrO₂/C-SiO₂ and Ni-La₂O₃/C-SiO₂ was reduced after the reaction compared to these of the Ni/C-SiO₂ catalyst. The promoter La₂O₃ not only improved the activity of the catalyst, but also reduced the amount of the carbon deposition on the catalyst. The total carbon conversion reached 52% for the CH₄-CO₂ reforming reaction using the Ni-La₂O₃/C-SiO₂ catalyst.