Ag/bauxite catalysts: Improved low-temperature activity and SO2 tolerance for H-2-promoted NH3-SCR of NOx

摘要

A series of Ag/bauxite catalysts were applied in H-2-promoted selective catalytic reduction (SCR) of NOx. In comparison with 3Ag/Al2O3, 3Ag/bauxite exhibits higher catalytic activity at low temperature, stronger resistance to SO2 poisoning and better regenerability in SCR of NOx. NOx conversion of 3Ag/bauxite at 100-200 degrees C is more than 60%, which is much higher than less than 7% in 3Ag/Al2O3. NH3-TPD and in situ DRIFTS studies confirm the presence of Lewis and Bronsted acid sites in Ag/bauxite, and Lewis acid sites are the major acid sites. H-2-TPR, UV-vis, in situ DRIFTS and DFT calculation show that FeOx and metallic Ag clusters are main active species in SCR of NOx at low temperature. (C) 2014 Elsevier B.V. All rights reserved.