Preferential CO oxidation in hydrogen-rich stream over Pt catalysts modified with alkali metals Part I. Catalytic performance

Abstract In preferential CO oxidation in H 2 -rich stream (PROX), the additive effect of potassium on Pt catalysts was more remarkable over Al 2 O 3 than over SiO 2 , ZrO 2 , Nb 2 O 5 and TiO 2 . The additive effect of potassium to Pt/Al 2 O 3 was more effective than other alkali metals. Especially, the presence of H 2 drastically promoted CO oxidation over Pt/Al 2 O 3 modified with potassium. On the other hand, the suppressing effect of steam on the PROX was more significant over K-Pt/Al 2 O 3 than over Pt/Al 2 O 3 , although the PROX activity of K-Pt/Al 2 O 3 was much higher than that of Pt/Al 2 O 3 even under the presence of steam. The different effect of steam addition to the PROX over K-Pt/Al 2 O 3 suggests that the active site can be Pt surface modified with potassium ions.