Low-Temperature SCR of NO with NH3 over USY-Supported Manganese Oxide-Based Catalysts
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A series of catalysts of manganese oxide, manganese–cerium and iron–manganese oxide supported on USY (ultra-stable Y zeolite) were studied for the low-temperature selective catalytic reduction (SCR) of NO with ammonia in the presence of excess oxygen. It was found that MnOx/USY have high activity and high selectivity to N2 in the temperature range 80-180 °C. The addition of iron and cerium oxide increased NO conversion significantly although the single-component Fe/USY and Ce/USY catalysts had low activities. Among the catalysts studied in this work, the 14% Ce-6% Mn/USY showed the highest activity. The results showed that this catalyst yielded nearly 100% NO conversion at 180 °C at a space velocity of 30 000 cm3 g-1 h-1. The only product is N2 (with no N2O) below 150 °C. The effects of the concentration of oxygen, NO and NH3 were studied and the steady-state kinetics were also investigated. The reaction order is 1 with respect to NO and zero with respect to NH3 on the 14% Ce-6% Mn/USY catalyst at 150 °C.
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