Surface structure change of a [Pt4(µ-CH3COO)8]/SiO2 catalyst active for the decomposition of formic acid

Abstract

Pt₄-cluster/SiO₂catalyst, prepared from the [Pt₄(µ-CH₃COO)₈] cluster, has shown remarkably high catalytic activity with 100% selectivity to CO₂ and H₂ for the decomposition of formic acid as compared with the Pt-particle/SiO₂ catalyst. In order to elucidate the genesis and the mechanism for catalysis by Pt₄-cluster/SiO₂, the samples were characterized by kinetics, Pt L_III-edge extended X-ray absorption fine structure (EXAFS), and FTIR spectroscopy. EXAFS and IR data revealed that the surface structure of the catalyst changed from the tetramer to dimers during an induction period, then to monomers which were active for the catalysis. Eventually Pt particles were formed which were of much lower catalytic activity. The structural transformations of the Pt₄-cluster/SiO₂ catalyst are discussed in relation to the catalytic reaction profiles.