XAFS Characterization of Platinum Clusters Synthesized in the Channel of a Mesoporous Zeolite

[Pt15(CO)30]2was synthesized by reductive carbonylation of HzPtCls in the channels of FSM-16 modified with NEt4CI. The platinum clusters in the channels whose diameter was 28 A were characterized by Pt edge EXAFS as well as FT-IR. UV-vis spectroscopy, and TEM measurements. After exposure of H2PtCldNEt&VFSM-16 to CO + H20 at 323 K, Pt carbonyl clusters were selectively produced. The Pt Lm edge EXAFS spectrum of this sample was exactly the same as that of [NE~]2[PtlS(C0)30]. and gave Pt-Pt distances typical of these types of platinum clusters at 2.68 and 3.08 A. Uniform platinum "particles" (15 A diameter) were observed in the channels of FSM-16 by a ?EM measurement; this suggests that [Ptls(CO)30]z was synthesized in the channel of FSM-16. The platinum clusters in the channel were converted to platinum metal particles by evacuation above 363 K. Pt Lrrr EXAFS spectra of these samples revealed that the bridge CO of the clusters were desorbed by the evacuation at 343 K while retaining their cluster framework the clusters were converted to PtSO-60 panicles by evacuation above 363 K.