Water gas shift reaction for the reformed fuels over Cu/MnO catalysts prepared via spinel-type oxide

Cu/MnO catalysts prepared via reduction of Cu-Mn spinel oxide were investigated for development of active Cu catalysts for the water gas shift reaction (WGSR). A Cu-Mn catalyst active for the WGSR was obtained after high temperature calcination at 900°C and subsequent reduction. The optimum Cu/ Mn ratio for catalytic activity of the Cu-Mn oxide system was 1/2. Nonstoichiometric Cu_1.5Mn_1.5O₄ phase existed stably when copper manganese oxide was calcined above 700°C. The optimized Cu-Mn spinel showed excellent WGSR activity when a larger percentage of CO was used, as in hydrocarbon reforming. Cu-Mn spinel oxides calcined above 900°C were easily reduced. This may be responsible for the high activity of the Cu/ MnO catalyst. Carbon dioxide in the reformed gas significantly depressed WGSR activity below 200°C, while CO conversion reached equilibrium at 200°C in the absence of CO₂.