Unveiling the role of high-valent copper cations in the selective catalytic reduction of NOx with NH3 at low temperature

Abstract

Cu3+ cation is present in some particular materials, however, to the best of our knowledge, it remains unclear what role of Cu3+ plays during selective catalytic reduction of NOx by NH3 (NH3-SCR) to date yet. Herein, LaCuO3-x supported on mesoporous Al2O3 was designed and constructed via an incipient wetness method, and the effect of Cu3+ on the adsorption and activation of NOx and NH3 species in the NH3-SCR of NOx was systematically probed by experiment and in-situ DRIFTS for the first time. It unravels that LaCuO3-x/meso-Al2O3 with abundant Cu3+ species exhibits a remarkably higher catalytic activity for NH3-SCR of NOx at low temperature range (100 ∼ 280 °C) than CuO/meso-Al2O3 counterpart because of the unique nature of Cu3+ species, which endows the more acid sites and higher redox property, thereby promoting the adsorption and activation of ammonia and NOx, and thereafter accelerating the intrinsic reaction rate of LaCuO3-x/meso-Al2O3. It should be the root reason resulting in the perceptibly higher catalytic activity of LaCuO3-x/meso-Al2O3 compared with that of CuO/meso-Al2O3 at low temperature. Therefore, the finding here offers great promise for the preparation of highly-efficient NH3-SCR catalyst with excellent catalytic activity at low temperatures in future.