(696d) Isolating the Effect of Metal Composition on Bi-Functional Pt/Ceria-Zirconia Low Temperature Reforming Catalysts

The harmful impact of greenhouse gas emissions and the need to protect the environment from these impacts has geared research on renewable energy sources. Following this trend, the focus of our research has been on the synthesis of improved catalytic materials for the conversion of biogas sourced methane and carbon dioxide to syngas using low-temperature reforming materials. Catalyst materials consisting of ceria-zirconia (CZO) support, Pt (0.16wt%), Ni (0.67-2.68 wt%) and/or Mg (0.5-2.0 wt%) were prepared using the incipient wetness method. Powder X-ray diffraction was used to identify crystal structures of the materials and the diffraction patterns representing the cubic-fluorite phase of ceria-zirconia was observed. The presence of the cubic-fluorite phase was supported by the Raman spectroscopy, which showed bands belonging to the F2g vibration bands of fluorite ceria. CO₂ desorption studies showed an increase in the amount of CO₂ desorbed from 21 to 30 µmol of CO₂/g_cat in the 0.16wt%Pt-2.7wt%Ni-CZO upon the addition of Mg. The reducibility of the Pt-Ni-CZO samples increased with increasing Ni content and CH₄ conversion correlated to sample reducibility. Increasing Mg amount resulted in a decrease in CH₄ conversion but helped improve H₂:CO. The increase in basicity with Mg addition was confirmed by CO₂-TPD FTIR studies which showed the Pt-Mg-CZO sample having stronger carbonates bands at higher temperatures in comparison to the Pt-Ni-CZO sample. The detection of coke (5.5 X 10^-4 g/g_cat.h) over the 0.16wt%Pt-2.7wt%Ni-CZO and its absence with the addition of Mg reveal that both Ni and Mg need to be incorporated into the catalyst formulation to obtain a balance between catalyst activity, selectivity, and stability. Our study on the effects of the metal contents provide key insights into optimal catalyst design and indicate the possibility of designing catalyst materials for intensified processes, due to the low-temperature activity and stability and reasonable selectivity.