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The effect of potassium additive on the catalytic activity of nickelmolybdenum alumina-supported systems has been studied by varying the molybdenum content within 5-18 mass% MoO 3 , reaction temperature from 180 to 400 (500)°C, and steam to gas ratio of 0.3, 0.7, and 1. It has been established that potassium reduces the activity of one-component Mo-containing samples, while, independent of molybdenum loading, nickel promotes activity within the whole temperature range studied and extends the temperature range of catalytic activity by about 70°C to lower reaction temperatures. A symbatic or additive, or antibatic catalytic behavior was observed with NiMo-containing samples depending on the atomic Ni/Mo ratio and temperature range. Potassium, being a third component in tri-component KNiMo-containing samples, enhances the water-gas shift (WGS) activity depending on the atomic K/(Ni ? Mo) ratio. The activity approaches the equilibrium conversion degree in the interval of 320-500°C. A decrease in the specific surface area of calcined and tested samples relative to the bare support shows close values indicating that the overall dispersion of the species is not changed during the catalytic test. Close examination indicated that the sample containing K 2 O, NiO, and MoO 3 of 4.9, 2.5, and 12.7 mass%, respectively, was found to be the most suitable catalyst for water-gas shift reaction with sulfur containing feed since it attains equilibrium conversion even at 300°C, and at a low steam to gas ratio of 0.3 atm. This catalyst demonstrates a stable and reproducible catalytic activity as inlet gas loading is increased.

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