Effect of the redox properties of support oxide over cobalt-based catalysts in high temperature water-gas shift reaction

The present study focused on the effect of reducibility of support oxide (CeO2, ZrO2, TiO2, and Al2O3) over the activity of cobalt-based catalysts in high temperature water-gas shift (HT-WGS) reaction. The H-2 temperature programmed reduction (TPR) and CO chemisorption characterization results showed that dispersion of cobalt over the support was increased with the increase of the reducibility of the support oxide. The supported catalysts were characterized by X-ray diffraction (XRD) and N-2 adsorption-desorption. The results indicated that the Co/CeO2 catalyst possesses the highest surface area and metal dispersion in the series; Co/CeO2 > Co/ZrO2 > Co/Al2O3 > Co/TiO2. The activity results showed that Co/CeO2 was the highly active among the tested catalysts in the temperature range of 350-550 degrees C. Moreover, the time-on-stream study revealed that the Co/CeO2 catalyst was relatively more stable than cobalt supported on ZrO2 and Al2O3 oxides. The excellent activity and stability of the Co/CeO2 catalyst were attributed to its high metal dispersion, which is found strongly dependent on the reducible nature of the support. (C) 2017 Elsevier B.V. All rights reserved.