January 11, 2019
Journal Article

Achieving Atomic Dispersion of Highly Loaded Transition Metals in Small-pore Zeolite SSZ-13: High-capacity and High-efficiency Low Temperature CO and Passive NOx Adsorbers

Yu Tang
Hristiyan Aleksandrov
Georgi Vayssilov
Yong Wang
Feng Gao
Janos Szanyi
Konstantin Khivantsev
Nicholas Jaegers
Libor Kovarik
Jonathan Hanson
Xiaoyan Zhang
Franklin Tao
Iskra Koleva
Synthesis of small-pore zeolitic materials with realistic loadings of transition metals atomically dispersed in the micropores has been a formidable challenge. Herein, we demonstrate a new simple and scalable route to high Pd and Pt loadings (>1 wt%) atomically dispersed in the micropores of a small-pore zeolite, 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 proce-dures. We determine the factors that govern the stabilization of M(II) species in the micropores of SSZ-13. Using a combined spectroscopic and DFT approach, we offer a unifying explana-tion for the discrepancies existing in available M-zeolite litera-ture. Moreover, we highlight the difference between the behav-ior of Pt and Pd during synthesis, and demonstrate that ionically dispersed Pd/SSZ-13 shows superior performance as a new class of environmentally important passive NOx Adsorber (PNA) material under practically relevant conditions. It thus represents the 2nd known metal-small pore zeolite material that has immediate industrial application, and the only known met-al-small pore zeolite material in which metal is close to 100 % uti-lized. In addition to NOx, the material performs remarkably for CO removal during cold start as well due to the formation of a mixed carbonyl-nitrosyl complex Pd(II)(CO)(NO).

Revised: January 11, 2019 | Published: December 17, 2018

Khivantsev K., N.R. Jaegers, L. Kovarik, J.c. Hanson, F. Tao, Y. Tang, and X. Zhang, et al. 2018. "Achieving Atomic Dispersion of Highly Loaded Transition Metals in Small-pore Zeolite SSZ-13: High-capacity and High-efficiency Low Temperature CO and Passive NOx Adsorbers." Angewandte Chemie International Edition 57, no. 51:16672-16677. PNNL-SA-136340. doi:10.1002/anie.201809343