The gold-ruthenium-iron oxide catalytic system for the low temperature water-gas-shift reaction - The examination of gold-ruthenium interactions

The water-gas-shift reaction has been carried out over Au-Ru supported on alpha-Fe2O3 catalyst at various reaction temperatures ranging from 373 to 513 K at atmospheric pressure. Activity of the bimetallic Au-Ru/iron oxide compared with Au/iron oxide and Ru/iron oxide catalysts has been found to be higher over all the reaction temperatures studied. All the fresh and spent samples were characterised by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), BET-surface area (S-BET), temperature programmed reduction (TPR) and carbon estimations were carried out for the spent catalysts. XRD analysis revealed the presence of An metallic particles on supported gold and alpha-Fe2O3 compound in all the fresh catalysts and Fe3O4 phases along with metallic Au in spent catalysts. However, no reflections due to Ru or RuO2 species were found either fresh or in spent catalysts. TPR analysis indicated the shift in reduction temperature due to An and/or Ru over Au-Ru/iron oxide compared to individual Au/iron oxide and Ru/iron oxide catalysts. Increase in particles sizes are observed by TEM analysis of the spent forms compared to fresh, which is accompanied by a significant reduction in BET-surface areas of fresh catalysts. (C) 2002 Elsevier Science B.V. All rights reserved.