Origin of the Improved Performance in Lanthanum-doped Silica-supported Ni Catalysts

Dry-reforming catalysts were prepared by supporting Ni nanoparticles (2-3nm) on La-doped silica. These materials display higher activity and stability in low-temperature dry reforming (773K) than Ni/SiO2 or Ni/La2O3. The La-doped silica-supported catalysts were found to have exclusively lanthanum silicate at their surface rather than La2O3 and/or SiO2. While an increasing amount of La was found to favor both CO2 adsorption capacity and strength, it also influenced the hydrogen adsorption strength on nickel particles significantly, as evidenced by H-2 temperature-programmed desorption analysis. Finally, CH4 temperature-programmed reduction analysis revealed that the CH4 cracking threshold temperature varies in the order: Ni-bulk<Ni/La-34@SiO2<Ni/La-2.1@SiO2<<Ni/SiO2<Ni/La2O3, which parallels the catalytic performance. Balancing the adsorption of CH4, H-2, and CO2 on supported Ni nanoparticles (2-3nm) on La-doped silica improves the catalytic performance of this low-temperature dry-reforming catalyst.