Zeolites are a critically important class of heterogeneous catalysts that are used commercially in large quantities for applications such as hydrocarbon catalysis and emissions reduction. Understanding how zeolites activate and degrade from macroscopic to atomic length scales is important for developing better, longer lasting zeolites. Unfortunately, nano-scale characterization is difficult due to the instability of zeolites under electron beam irradiation and the lack of high angle annular dark field (HAADF) z-contrast from the similar z framework elements (Si, Al, O, P). Atom probe tomography (APT), as it is a time-of-flight mass spectroscopy-based technique, is not restricted in this way.
Within the last decade, APT has proven to be a useful technique for zeolite analysis, and several studies have shed light upon their atomistic activation and degradation mechanisms [1-11]. For example, coke molecules in ZSM-5, SSZ-13, and SAPO-34 have been spatially linked to active catalysis lattice sites which degrades the catalytic performance [2, 3, 5, 7, 9]. In addition, APT data revealed why Cu-exchanged SSZ-13 outperforms Cu-exchanged ZSM-5 for NOx diesel exhaust reduction in both conversion rate and longevity [10]. Although most of the experiments were run at ORNL with a LEAP 4000XHR (3.4 eV laser), fresh and methanol reacted ZSM-5 zeolites were recently run in a LEAP 6000XR at CAMECA with a 4.7 eV laser, which has shown promising yield results.
Overall, APT has many advantages for characterizing zeolites. The successes and challenges associated with APT zeolite analysis using the aforementioned examples as well as a data comparison from identical samples run using a LEAP 4000XHR and LEAP6000XR will be presented.
The LEAP 4000XR research was supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. The LEAP 6000XR experiments were run at CAMECA Instruments in Madison, WI. The authors would like to thank James Burns for assistance in performing APT sample preparation and running the APT experiments.
10AM Tuesday June 13 CST: CLICK HERE
About the presenter:
Jon Poplawsky
Senior Research Staff
Oak Ridge National Laboratory
Jon received his bachelor’s degree from The University of Scranton in 2007 before receiving his Ph.D in Physics at Lehigh University in 2012 where he started his microscopy journey. Following his graduate studies, Jonathan worked as a post-doctoral research associate in the Scanning Transmission Electron Microscopy (STEM) group at Oak Ridge National Laboratory (ORNL) under Stephen J. Pennycook. Following his postdoctoral studies, Jon was hired to be in charge of the APT laboratory at ORNL. His main research interests are focused on determining interfacial solute segregation at the atomic level with the end goal of improving energy materials using microscopy.
[1] D.E. Perea, I. Arslan, J. Liu, Z. Ristanović, L. Kovarik, B.W. Arey, J.A. Lercher, S.R. Bare, B.M. Weckhuysen, Determining the location and nearest neighbours of aluminium in zeolites with atom probe tomography, Nat. Commun. 6(1) (2015) 7589.
[2] J. Schmidt, L. Peng, J. Poplawsky, B.M. Weckhuysen, Nanoscale Chemical Imaging of Zeolites Using Atom Probe Tomography, Angew. Chem. Int. Ed. 57(33) (2018) 10422-10435.
[3] J.E. Schmidt, J.D. Poplawsky, B. Mazumder, Ö. Attila, D. Fu, D.A.M. de Winter, F. Meirer, S.R. Bare, B.M. Weckhuysen, Coke Formation in a Zeolite Crystal During the Methanol-to-Hydrocarbons Reaction as Studied with Atom Probe Tomography, Angew. Chem. Int. Ed. 128(37) (2016) 11339-11343.
[4] S.H. van Vreeswijk, M. Monai, R. Oord, J.E. Schmidt, E.T.C. Vogt, J.D. Poplawsky, B.M. Weckhuysen, Nano-scale insights regarding coke formation in zeolite SSZ-13 subject to the methanol-to-hydrocarbons reaction, Catalysis Science & Technology (2022).
[5] J.E. Schmidt, X. Ye, I.K. van Ravenhorst, R. Oord, D.A. Shapiro, Y.-S. Yu, S.R. Bare, F. Meirer, J.D. Poplawsky, B.M. Weckhuysen, Probing the Location and Speciation of Elements in Zeolites with Correlated Atom Probe Tomography and Scanning Transmission X-Ray Microscopy, ChemCatChem 11(1) (2018) 488-494.
[6] S.H. van Vreeswijk, M. Monai, R. Oord, J.E. Schmidt, A.N. Parvulescu, I. Yarulina, L. Karwacki, J.D. Poplawsky, B.M. Weckhuysen, Detecting Cage Crossing and Filling Clusters of Magnesium and Carbon Atoms in Zeolite SSZ-13 with Atom Probe Tomography, JACS Au 2(11) (2022) 2501-2513.
[7] J.E. Schmidt, L. Peng, A.L. Paioni, H.L. Ehren, W. Guo, B. Mazumder, D.A.M. de Winter, Ö. Attila, D. Fu, A.D. Chowdhury, K. Houben, M. Baldus, J.D. Poplawsky, B.M. Weckhuysen, Isolating Clusters of Light Elements in Molecular Sieves with Atom Probe Tomography, Journal of the American Chemical Society 140(29) (2018) 9154-9158.
[8] J. Poplawsky, S.V. Vreeswijk, J. Schmidt, M. Monai, F. Zand, B. Weckhuysen, Nanoscale Chemical Imaging in Zeolite Catalysts by Atom Probe Tomography, Microsc. Microanal. 27(S1) (2021) 984-985.
[9] J.D. Poplawsky, J.E. Schmidt, B. Mazumder, W. Guo, Ö. Attila, D. Fu, D.A.M. de Winter, F. Meirer, S.R. Bare, B.M. Weckhuysen, Nanoscale Chemical Imaging of Coking Mechanisms in a Zeolite ZSM-5 Crystal by Atom Probe Tomography, Microsc. Microanal. 23(S1) (2017) 674-675.
[10] J.E. Schmidt, R. Oord, W. Guo, J.D. Poplawsky, B.M. Weckhuysen, Nanoscale tomography reveals the deactivation of automotive copper-exchanged zeolite catalysts, Nat. Commun. 8(1) (2017) 1666.
[11] R.M. Danisi, A. Lucini Paioni, J.E. Schmidt, K. Houben, J.D. Poplawsky, M. Baldus, B. Weckhuysen, E.T.C. Vogt, Revealing Long- and Short-range Structural Modifications within Phosphorus-treated HZSM-5 Zeolites by Atom Probe Tomography, Nuclear Magnetic Resonance and Powder X-Ray Diffraction, Phys. Chem. Chem. Phys. (2018) 1-15.