Additive effect of alkali metal ions on preferential CO oxidation over Pt/Al2O3

In the preferential CO oxidation under H2-rich gas, CO conversion and selectivity of CO oxidation were enhanced by the addition of alkali metal ions (M = Li, Na, K, Rb, Cs) to Pt/Al2O3 in the range of the molar ratio (M/Pt) lower than 3, and TOFs monotonously increased along with the basicity strength of added alkali metal ions. In contrast, in the range of M/Pt ⩾ 5, the order of additive effect was K > Na > Rb > Cs. This can be related to a moderate strength of basicity of potassium. In addition, the promoting effect of the presence of H2 on CO oxidation was also clearly observed on K–Pt/Al2O3.