Open AccessPd/SAPO-34 passive NO x adsorbers: Stable Pd ion adsorption sites in six-member rings
Author(s) -
Nana Zhang,
Xin Yin,
Ruirui Li,
Dongxu Han,
Junxiu Jia,
Qian Li,
Jin Wang,
Zhaoliang Zhang
Publication year - 2021
Publication title -
materials research express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.383
H-Index - 35
ISSN - 2053-1591
DOI - 10.1088/2053-1591/abeb86
Subject(s) - chabazite , adsorption , zeolite , ion , desorption , chemistry , diesel fuel , topology (electrical circuits) , materials science , inorganic chemistry , organic chemistry , catalysis , mathematics , combinatorics
Pd/zeolites with chabazite (CHA) topology are effective passive NO x adsorbers (PNAs), which are promising for the removal of NO x from diesel exhausts during cold start to meet increasingly stringent emission regulations. In this work, Pd/SAPO-34 zeolites with different preparation methods and Pd contents were developed and exhibited high NO adsorption performance. Three Pd species in Pd/SAPO-34, including well-dispersed PdO x clusters, Pd ions in the eight- and six-member rings (8MRs and 6MRs) of zeolites, are NO adsorption sites in the absence of H 2 O in the feed, demonstrated by a good linear relationship between the total Pd contents and NO x desorption amounts. However, in the presence of H 2 O, only Pd ions in 6MRs are stable NO adsorption sites and provide the continuous NO adsorption, due to the limited mobility of the Pd ions in 6 MRs with small pore size. This new finding points out a definite direction for the rational design of high-performance PNAs to eliminate NO x during the cold start of diesel vehicles.