The functions of Pt located at different positions of HZSM-5 in H2-SCR

Abstract Series of Pt/HZSM-5 catalysts ( x  = 0.1–0.5) were prepared by impregnating H 2 PtCl 6 or Pt(NO 3 ) 2 on HZSM-5 and characterized by FTIR and XPS. It was found that Pt is predominantly located on the zeolite outside surface for the catalysts prepared from H 2 PtCl 6 , whereas large portion of Pt existed in the zeolite channels for the catalysts prepared from Pt(NO 3 ) 2 . In the H 2 -SCR, the Pt on the zeolite outside surface plays the role of activating H 2 , while that in the zeolite channels merely adsorbs NO x species for the reaction. For the catalysts, proper NO x adsorption capacity matching the property activating H 2 is indispensable for increasing the H 2 efficiency and the N 2 selectivity. Some cations such as Al 3+ capable of accepting more NO x species in the zeolite channels effectively improved the catalytic performance.