Activity and characterization of Rh/Al 2O 3 and Rh–Na/Al 2O 3 catalysts for the SCR of NO with CO in the presence of SO 2 and HCl

Abstract

SO 2 and HCl are major pollutants emitted from waste incineration processes. Both pollutants are difficult to remove completely and can enter the catalytic reactor. In this work, the effects of SO 2 and HCl on the performance of Rh/Al 2O 3 and Rh–Na/Al 2O 3 catalysts for NO removal were investigated in simulated waste incineration conditions. The characterizations of the catalysts were analyzed by BET, SEM/EDS, XRD, and ESCA. Experimental results indicated the 1%Rh/Al 2O 3 catalyst was significantly deactivated for NO and CO conversions when SO 2 and HCl coexisted in the flue gas. The addition of between 2 and 10 wt.% Na promoted the activity of the 1%Rh/Al 2O 3 catalyst for NO removal, but decreased the CO oxidation and BET surface area. The catalytic activity for NO removal was inhibited by HCl as a result of the formation of RhCl 3. Adding Na to the Rh/Al 2O 3 catalyst decreased the inhibition of SO 2 because of the formation of Na 2SO 4, which was observed in the XRD and ESCA analyses. SEM mapping/EDS showed that more S was residual on the surface of the Rh–Na/Al 2O 3 catalyst than Cl.