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A laboratory investigation of NO x reduction by NH 3 over sulfated and unsulfated CuO/γ-Al 2 O 3 was carried out. The rate of the selective catalytic reduction (SCR) reaction with excess O 2 over presulfated sorbent between 325 and 425°C in the absence of H 2 O and HCl was quantified by a first-order expression with a pre-exponential factor of 3.5 × 10 9 cm 3 gm -1 s -1 and an activation energy of 84.5 kJ/mol. HCl and H 2 O were shown to be detrimental to the SCR process. The behavior of NO and NH 3 over the fresh sorbent has an important bearing on reactor design. When NO is not present, NH 3 is rapidly oxidized to NO and N 2 O above 250°C. When both NO and NH 3 are present, the SCR reaction still occurs, but the catalyst activity is much lower. However, above 425°C the selectivity of fresh sorbent is poor with a significant amount of NH 3 being oxidized. Some NH 3 is also reduced to N 2 .

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