Synthesis of small-pore zeolitic materials with realistic loadings of (transition) metals ionically dispersed in the micropore has been a challenge in the field of catalysis. Herein, we demonstrate a new simple and scalable route to 1 and higher wt% of Pd and Pt ionically dispersed in the micropore of small-pore H-SSZ-13. Unlike all previous methods that require addition of expensive transition metal precursor complexes into the synthesis gel and produce low loading of atomically dispersed species, this method does not require any complicated synthetic procedures. We determine the factors that govern the stabilization of M(II) species in micropores of SSZ-13, and offer a unifying explanation for discrepancies found in available literature regarding synthesis of well-defined M-small pore zeolite materials. Moreover, we highlight the differences between the behavior of Pt and Pd during synthesis, and demonstrate that well-dispersed Pd/SSZ-13 species show record-breaking performance as Passive NOx Adsorber (PNA) materials for which atomically dispersed Pd sites are the active sites and thus have great industrial potential.
The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. The research described in this paper was performed in the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOEâs Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.