Abstract: Co²⁺ion has the adsorption rate smaller than that of molybdate ion on γ-Al₂O₃ butwith larger apparent diffution coefficient(D_Co=1.2×10^-5, DM.=4.4×10^-6cm²/s at 25℃).The adsorption curves of Co and Mo consist with Langmuir and Freundlich isotherm,respectively. Adsorption of Mo decreased by increasing the pH of impregnating solutionand adsorptions of Co and Mo were mutually enhanced due to coadsorption in a mixedsolution of cobalt nitrate and ammonium heptamolybdate at pH=5.3.Most of Mo wasdistributed in the outter shell of Al₂O₃ in the catalyst prepared by pore volume imrpeg-nating with Co-Mo mixed solution at low pH value owing to its large adsorytivity, buta more uniform distribution could be obtained at high pH solution. Adsorption of K₂CO₃ on Co-Mo catalyst can be described by Langmuir isotberm. An even distribution of K on Co-Mo/Al₂O₃ was obtained by pore volume impregnating with enough quantity of K₂CO₃ in the impregnating solution. An even distributed catalyst is more active than an unevendistributed one with the same composition for water gas shift reaction.

Key words: cobalt molybdenum catalyst, cobalt molybdenum potassium catalyst, water gas shift catalyst