Insight into hydrothermal aging effect on Pd sites over Pd/LTA and Pd/SSZ-13 as PNA and CO oxidation monolith catalysts

Aiyong Wang; Kristina Lindgren; Mengqiao Di; Diana Bernin; Per-Anders Carlsson; Mattias Thuvander; Louise Olsson

doi:10.1016/j.apcatb.2020.119315

Insight into hydrothermal aging effect on Pd sites over Pd/LTA and Pd/SSZ-13 as PNA and CO oxidation monolith catalysts
Journal article, 2020

In this study, Pd/LTA and Pd/SSZ-13 were prepared and then hydrothermally aged at the temperature of 750, 800, 850, and 900 °C. Multiple Pd species, including isolated Pd ions (Pd2+ and [Pd(OH)]+) and 1∼2 nm PdOx nanoparticles, were presented in two fresh samples. The Pd/LTA sample showed remarkable hydrothermal stability, but the Pd/SSZ-13 sample experienced severe damage after aging at 900 °C. The destruction of the aged Pd/SSZ-13 sample led to the migration and sintering of PdOx nanoparticles, which formed bulk PdOx particles on the surface of the zeolite crystallite. A large number of PdOx nanoparticles were retained after aging of the Pd/LTA sample. Pd/LTA contained a higher concentration of Pd2+ sites, while Pd/SSZ-13 had more [Pd(OH)]+ sites. It is found that the improvement of NO adsorption ability with CO addition onto Pd2+ was more significant than onto [Pd(OH)]+.

PNA

Hydrothermal aging

LTA

SSZ-13