Nanoscale tomography reveals the deactivation of automotive copper-exchanged zeolite catalysts

• Published in: Nature communications Vol. 8; no. 1; pp. 1666 - 8
• Main Authors: Schmidt, Joel E., Oord, Ramon, Guo, Wei, Poplawsky, Jonathan D., Weckhuysen, Bert M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21-11-2017; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/299; 639/301/930/12; 639/638/77/887; Aluminum; Ammonia; Automobile industry; Automotive engineering; Catalysis; Catalysts; Catalytic activity; Clustering; Commercialization; Copper; Deactivation; Humanities and Social Sciences; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; multidisciplinary; Science; Science (multidisciplinary); Selective catalytic reduction; Tomography; Vehicle emissions; Zeolites
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-017-01765-0

Copper-exchanged zeolite chabazite (Cu-SSZ-13) was recently commercialized for the selective catalytic reduction of NO
X
with ammonia in vehicle emissions as it exhibits superior reaction performance and stability compared to all other catalysts, notably Cu-ZSM-5. Herein, the 3D distributions of Cu as well as framework elements (Al, O, Si) in both fresh and aged Cu-SSZ-13 and Cu-ZSM-5 are determined with nanometer resolution using atom probe tomography (APT), and correlated with catalytic activity and other characterizations. Both fresh catalysts contain a heterogeneous Cu distribution, which is only identified due to the single atom sensitivity of APT. After the industry standard 135,000 mile simulation, Cu-SSZ-13 shows Cu and Al clustering, whereas Cu-ZSM-5 is characterized by severe Cu and Al aggregation into a copper aluminate phase (CuAl
2
O
4
spinel). The application of APT as a sensitive and local characterization method provides identification of nanometer scale heterogeneities that lead to catalytic activity and material deactivation.
Cu-exchanged zeolite chabazite has superior stability over other catalysts in automotive NO
x
reduction. Here, the authors use atom probe tomography to create 3D nanoscale reconstructions of two Cu-containing zeolite catalysts, providing a complete picture of their deactivation mechanisms during aging.