(758e) 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

1. Khivantsev, N. R. Jaegers, L. Kovarik, J. C. Hanson, F. F. Tao, Y. Tang, X. Zhang, I. Z. Koleva, H. A. Aleksandrov, G. N. Vayssilov, Y. Wang, F. Gao, J. Szanyi, Angew. Chem. Int. Ed., 2018, 57, 16672-16677.
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
3. Aylor, L, J. Lobree, J. Reimer, A. Bell, J. Catal. 1997, 172, 453-462.
4. Chakarova, E. Ivanova, K. Hadjiivanov, D. Klissurski, H. Knozinger, Phys. Chem. Chem. Phys. 2004, 6, 3702–3709.