Selective catalytic reduction

About: Selective catalytic reduction is a research topic. Over the lifetime, 10502 publications have been published within this topic receiving 226291 citations.

Porous metal–organic framework MIL-100(Fe) as an efficient catalyst for the selective catalytic reduction of NOx with NH3

Abstract: The development of an efficient catalyst with excellent catalytic activity and high SO2 resistance at low temperatures (<300 °C) remains a challenge for the selective catalytic reduction (SCR) reaction. In this study, we report that MIL-100(Fe) is an alternative catalyst for the SCR of NOx with NH3, and it exhibits higher NOx conversion than the conventional V2O5–WO3/TiO2 catalyst below 300 °C. In addition, the effect of H2O and SO2 on the catalytic activity is reversible, and NOx conversions are recovered after ceasing the flow of SO2 and H2O. In situ diffuse reflectance infrared Fourier transform spectroscopy results indicate that both ionic NH4+ and coordinated NH3 existed on MIL-100(Fe) and that the reaction primarily followed the Langmuir–Hinshelwood mechanism, in which NH4+ reacts with NO2 formed from NO oxidation over iron sites. Furthermore, the redox properties of the iron species (Fe3+ + e− ↔ Fe2+) could play a significant role in activating the reactants.

Selective catalytic reduction of nitrogen monoxide by decane on copper-exchanged beta zeolites

Abstract: The selective catalytic reduction (SCR) of NO by decane has been investigated on a series of copper exchanged beta zeolite (BEA), and the catalytic behaviour has been compared to Cu-MFI. The different solids were characterised by temperature programmed reduction by H2 and temperature programmed desorption of NO in order to determine the nature, reducibility and accessibility of copper species. Only CuO aggregates are formed on Cu/H-BEA whatever the Cu content. By contrast, isolated Cu2+ are the main species occurring on Cu/Na-BEA when Cu exchange level is lower than 120% and the accessibility to Cu sites is high (NO/Cu≥ 0.45). At higher content, CuO aggregates exists too, and the accessibility decreases to NO/Cu≈ 0.29. The activity in SCR of NO by decane of Cu/Na-BEA goes through a maximum for 113% Cu exchange. This sample is less active than Cu/MFI at high temperature, but much more active at low temperature. The intrinsic activity at 673 K per accessible Cu site remains very similar for the different Cu/Na-BEA samples. This is attributed to temperatures of the reduction step Cu2+ → Cu2+ very close whatever the copper content.