Abstract
Within a restricted range of metal loadings, the presence of small Pt particles on a hydroxylated fully oxidized TiO2 surface leads to the appearance of unusual chemical behavior. The chemisorption strength of styrene is markedly increased and the partial oxidation activity intrinsic to the hydroxylated titania is replaced by partial hydrogenation activity: styrene is converted to ethylbenzene instead of acetophenone. UPS and X-ray photoelectron spectroscopy data indicate that in this regime of platinum loading the Pt particles are subject to the so-called quantum size effect (QSE) and must therefore be of nanoscopic dimensions. The appearance of hydrogenation activity in the presence of these very small platinum particles may be rationalized in terms of a QSE/bifunctional catalysis mechanism involving water dissociation on the Pt followed by Ha spill-over over at the Pt/titania boundary where captured, strongly bound, styrene molecules undergo hydrogenation.
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Sykes, E.C.H., Tikhov, M.S. & Lambert, R.M. Quantum Size Effects in Catalysis by TiO2/Platinum: The Switch from Partial Oxidation to Partial Hydrogenation of Styrene. Catalysis Letters 82, 169–173 (2002). https://doi.org/10.1023/A:1020558726477
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DOI: https://doi.org/10.1023/A:1020558726477