Catalysis Letters, Vol.88, No.1-2, 23-30, 2003
Evolution of transition metal speciation in the preparation of supported catalysts: halogenoplatinate(IV) on silica
H2PtCl6 adsorption on silica and the evolution of the Pt(IV) speciation upon drying and rewetting were studied by Pt-195 NMR, UV-visible, and EXAFS spectroscopies. Upon drying at 40 degreesC, H2PtCl6 forms outer-sphere complexes with silica. At 90 degreesC, inner-sphere complexes are formed; this grafting is reversible upon rehydration. Each surface Pt(IV) species is characterized by a specific reduction temperature, as evidenced by TPR.