title: Stability of a Bifunctional Cu-Based Core@Zeolite Shell Catalyst for Dimethyl Ether Synthesis Under Redox Conditions Studied by Environmental Transmission Electron Microscopy and In Situ X-Ray Ptychography.
abstract: When using bifunctional core@shell catalysts, the stability of both the shell and core-shell interface is crucial for catalytic applications. In the present study, we elucidate the stability of a CuO/ZnO/Al2O3@ZSM-5 core@shell material, used for one-stage synthesis of dimethyl ether from synthesis gas. The catalyst stability was studied in a hierarchical manner by complementary environmental transmission electron microscopy (ETEM), scanning electron microscopy (SEM) and in situ hard X-ray ptychography with a specially designed in situ cell. Both reductive activation and reoxidation were applied. The core-shell interface was found to be stable during reducing and oxidizing treatment at 250°C as observed by ETEM and in situ X-ray ptychography, although strong changes occurred in the core on a 10 nm scale due to the reduction of copper oxide to metallic copper particles. At 350°C, in situ X-ray ptychography indicated the occurrence of structural changes also on the µm scale, i.e. the core material and parts of the shell undergo restructuring. Nevertheless, the crucial core-shell interface required for full bifunctionality appeared to remain stable. This study demonstrates the potential of these correlative in situ microscopy techniques for hierarchically designed catalysts.
authors.affiliation: 1Institute for Chemical Technology and Polymer Chemistry,Karlsruhe Institute of Technology,76131 Karlsruhe,Germany.
authors.forename: Sina
authors.initials: S
authors.lastname: Baier
authors.affiliation: 2Center for Electron Nanoscopy,Technical University of Denmark,2800 Kgs. Lyngby,Denmark.
authors.forename: Christian D
authors.initials: CD
authors.lastname: Damsgaard
authors.affiliation: 4Institute of Chemical Reaction Engineering,Friedrich-Alexander University Erlangen-Nürnberg (FAU),91058 Erlangen,Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Klumpp
authors.affiliation: 5Deutsches Elektronen-Synchrotron DESY,Notkestr. 85,22607 Hamburg,Germany.
authors.forename: Juliane
authors.initials: J
authors.lastname: Reinhardt
authors.affiliation: 1Institute for Chemical Technology and Polymer Chemistry,Karlsruhe Institute of Technology,76131 Karlsruhe,Germany.
authors.forename: Thomas
authors.identifier: 0000-0002-8891-985X
authors.initials: T
authors.lastname: Sheppard
authors.affiliation: 2Center for Electron Nanoscopy,Technical University of Denmark,2800 Kgs. Lyngby,Denmark.
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Balogh
authors.affiliation: 2Center for Electron Nanoscopy,Technical University of Denmark,2800 Kgs. Lyngby,Denmark.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kasama
authors.affiliation: 1Institute for Chemical Technology and Polymer Chemistry,Karlsruhe Institute of Technology,76131 Karlsruhe,Germany.
authors.forename: Federico
authors.initials: F
authors.lastname: Benzi
authors.affiliation: 2Center for Electron Nanoscopy,Technical University of Denmark,2800 Kgs. Lyngby,Denmark.
authors.forename: Jakob B
authors.initials: JB
authors.lastname: Wagner
authors.affiliation: 4Institute of Chemical Reaction Engineering,Friedrich-Alexander University Erlangen-Nürnberg (FAU),91058 Erlangen,Germany.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Schwieger
authors.affiliation: 5Deutsches Elektronen-Synchrotron DESY,Notkestr. 85,22607 Hamburg,Germany.
authors.forename: Christian G
authors.initials: CG
authors.lastname: Schroer
authors.affiliation: 1Institute for Chemical Technology and Polymer Chemistry,Karlsruhe Institute of Technology,76131 Karlsruhe,Germany.
authors.forename: Jan-Dierk
authors.initials: JD
authors.lastname: Grunwaldt
keywords: ETEM; X-ray microscopy; core–shell catalyst; correlative imaging; dimethyl ether