Weighting Variation of Water-Gas Shift in Steam Reforming of Methane over Supported Ni and Ni-Cu Catalysts

In this work, catalysts of 2 wt % Ni supported on samaria-doped ceria (SDC), gadolinia-doped ceria, and -Al2O3, as well as SDCsupported Ni-Cu catalysts with 0.5 wt % Ni or Cu and addition of 0.01-0.1 wt % Cu or Ni were prepared. Activity tests for steam reforming of methane over these catalysts were carried out at temperatures of 673-823 K. A method for analyzing the weighting of the water-gas shift (WGS) activity in steam reforming is proposed. The effects of temperature, support, and Ni-Cu ratio on the WGS weighting variations were studied. The results indicate that the weighting of the WGS activity decreases with increasing temperature. The extent of the variation of the WGS weighting is larger with doped ceria as the support than with -Al2O3. The addition of Cu into a Ni catalyst enhances the WGS activity, and this enhancement effect can be quantitatively related to the amount of the bimetallic Cu-Ni species. The simple analysis of WGS weighting is able to give some ideas on the operation and catalyst design for achieving a good WGS activity.