Effect of zeolite protons on Pd particle size and H2 chemisorption
- 1 January 1992
- journal article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions
- Vol. 88 (15) , 2291-2295
- https://doi.org/10.1039/ft9928802291
Abstract
Zeolite protons enhance metal dispersion by chemically anchoring small reduced Pd particles; they also markedly reduce the propensity of Pd to chemisorb H2. Whereas the true metal dispersion, derived from Pd–Pd coordination numbers determined by EXAFS is higher for Pd/HY than for Pd/NaHY or Pd/NaNH4Y, conventional H2 chemisorption gives lower H : Pd ratios for the samples with higher dispersion. This apparent discrepancy is confirmed by static and dynamic adsorption measurements and by rapid isotope exchange between gaseous D2 and zeolite protons. Remarkably, the mononuclear Pd proton adduct [Pd1—Hx]x+ does not catalyse D–H isotope exchange at 300 K, because it apparently does not chemisorb D2 or H2.Keywords
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