Alkali metal deactivation of Mn–CeOx/Zr-delaminated-clay for the low-temperature selective catalytic reduction of NOx with NH3

• The effects of alkali metals on Mn–CeOx/Zr-delaminated-clay in the low temperature SCR of NOx.
• Characterization of Mn–CeOx/Zr-delaminated-clay deactivated by alkali metals.
• Regeneration of Mn–CeOx/Mn–CeOx/Zr-delaminated-clay by washing with water and acidic solution.

Mn–CeOx/Zr-delaminated-clay has proven to be a promising low-temperature selective catalytic reduction (SCR) catalyst. To investigate the effects of alkali metals (potassium and sodium) on Mn–CeOx/Zr-delaminated-clay for the low-temperature SCR of NOx by NH3, fresh and alkali-deactivated Mn–CeOx/Zr-delaminated-clays were prepared under laboratory conditions. The SCR activity of each catalyst was measured for the removal of NO with NH3 in a fixed-bed flow reactor. The properties of the catalysts were characterized by XRD, H2-TPR, NH3-TPD, BET and XPS analyses. These results indicate that alkali metals seriously reduced catalytic activity, with potassium having a stronger deactivation effect than sodium. The addition of alkali metals to the catalysts lowered manganese oxide reducibility, allowed decrease of specific surface areas, increased Mn binding energy and lowered the number of acidic sites on the surface. Dissolution of Na, K from the catalysts by washing with water was found to be the best method for regenerating catalysts that were not greatly deactivated by alkali metals.

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