First Detection and Characterization of Super-Electrophilic Metal (Pt+2, Pd+2, Ag+) Cations in Zeolite SSZ-13: Novel Chemistry for Adsorption and Catalysis Applications

We provide the first observation and characterization of super-electrophilic metal cations. To identify and characterize them, we synthesized high loadings (1 wt%) of uniform atomically dispersed Pd⁺² cations in a small-pore zeolite SSZ-13 [1,2]. Because of the uniformity and selective formation of the Pd⁺²//2Al species for this material, we were able to unravel their unique chemistry. Previously, their spectroscopic signatures have been assigned to Pd⁺³ and Pd⁺⁴ species [3,4]. However, herein we show that in fact [Pd⁺²//2Al] ions form selectively. We demonstrate that these Pd⁺²ions are super-electrophilic in nature and quantify super-electrophilicity of a metal (ion) for the first time with the aid of high-resolution in-situ XPS studies (combined with FTIR spectroscopy and DFT calculations).

With aid of FTIR and DFT, we unravel the novel chemistry of Pd⁺²/SSZ-13 and its complexes with CO, NO, C₂H₄. We also show the first example of comprehensive modeling of a Pd(Pt)/zeolite system including the interaction with the small molecules (CO,NO,ethylene) – these interactions are of great importance for adsorption (e.g., PNA) and catalysis (ethylene transformations) [1,2].

References

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2. Khivantsev, N. R. Jaegers, I. Z. Koleva, H. A. Aleksandrov, L. Kovarik, M. Engelhard, F. Gao, Y. Wang, G. Vayssilov, J. Szanyi, Stabilization of Super Electrophilic Pd⁺² Cations in Small-Pore SSZ-13 Zeolite, Chemrxiv 2019
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