Water–gas shift reactions on potassium- and zirconium-promoted cobalt molybdenum carbide catalysts Original Research Article

The preparation of carburized CoMo with alumina, potassium or zirconium added and their activity for the water–gas shift reaction at 453 K were investigated on the basis of XRD, temperature-programmed desorption (TPD) after H218O adsorption, transmission electron microscopy, and X-ray photoelectron spectroscopy. The carburized 5 wt% Al2O3/Co46.5Mo46.5K2Zr5 catalyst exhibited the highest CO conversion and TOF. The TPD experiment after H218O adsorption showed that the Zr-containing catalysts produced Co6Mo6C1 from β-Mo2C and Co metal, but the catalyst without zirconium produced MoO2 and Co3Mo. The presence of potassium significantly promotes water dissociation while zirconia prevented the oxidation of β-Mo2C. The Al2O3KZr-promoted CoMo catalyst exhibited a higher distribution of Co0 and Co2+ than the catalysts containing either zirconium or potassium in the presence of the Co3+ ions. The Al2O3KZr-promoted CoMo catalyst contained β-Mo2C, small Co metal particles and Co6Mo6C1 along with zirconia, potassium and alumina.