Microkinetics of Water−Gas Shift over Sulfided Mo/Al2O3Catalysts

A microkinetic model was developed to explain the catalysis of the water−gas shift reaction by sulfided, alumina-supported molybdenum. In this model, the reaction takes place through a regenerative (reduction−oxidation) scheme wherein the catalyst surface is alternately oxidized by water and then reduced by carbon monoxide. The surface of the catalyst is equilibrated with gas-phase H 2 S under all reaction conditions studied. Coverages predicted by the model are consistent with the adsorption behavior of molybdenum sulfide catalysts. Simulations indicate that the effects of steam and H 2 S levels are closely related. A maximum in CO conversion with increasing steam level may only occur at certain H 2 S levels, and the ordering of CO conversion with increasing H 2 S levels may invert as the steam level is changed.