Methane combustion activity of alumina supported Pt, Pd, and Rh catalysts modified by high-energy ion beam irradiation

Abstract

100 keV O⁺ or N⁺ ion implantation was used to study the irradiation effect on the methane combustion activity of 1 mass%Pd, Pt, and Rh supported on γ-Al₂O₃ . The catalytic activity of both Pt/Al₂O₃ and Rh/Al₂O₃ was enhanced by the implantation, probably due to the improved dispersion of noble metals. On the other hand, the activity of Pd/Al₂O₃ decreased substantially with an increased dose amount of O⁺ or N⁺ . The Pd 3d_5/2 XPS measurement demonstrated that the as-prepared catalyst contains PdO, which is reduced to Pd metal with increasing ion implantation. This irradiation-induced reaction process also resulted in not only a significant increase of the Pd particle size from 3 to 20 nm, but also a phase transformation of γ- to α-Al₂O₃ after implanting O⁺ of 7.5×10¹⁸ ion g^–1 .