Effects of alkali metal poisoning and cobalt modification on the NH3 adsorption behavior on the MnxOy/Ni (111) surface: A DFT-D study

The effects of alkali metal (potassium and sodium) poisoning and cobalt modification on the NH3 adsorption behavior on the MnxOy/Ni (1 1 1) surface were studied using a density functional theory. Alkali metals have strong inhibition on the activity of catalyst because they can cover the Mn sites to block the NH3 adsorption, which can also decrease the activity of the Mn sites on the catalyst surface. In addition, since potassium atom is easier to adsorb on the catalyst surface than sodium atom, the inhibitory effect of potassium is larger than that of sodium. After cobalt modification, the adsorption energies of potassium atom are decreased and activity of Mn sites on the poisoned catalyst surface is recovered. Cobalt can provide a number of strong acid sites for NH3 adsorption, which is favorable to promoting the NOx conversion of Co modified foam nickel supported manganese-based catalyst under alkali metal poisoning conditions. The calculated results are consistent with the experimental results.