title: Effects of Coke Deposits on the Catalytic Performance of Large Zeolite H-ZSM-5 Crystals during Alcohol-to-Hydrocarbon Reactions as Investigated by a Combination of Optical Spectroscopy and Microscopy.
abstract: The catalytic activity of large zeolite H-ZSM-5 crystals in methanol (MTO) and ethanol-to-olefins (ETO) conversions was investigated and, using operando UV/Vis measurements, the catalytic activity and deactivation was correlated with the formation of coke. These findings were related to in situ single crystal UV/Vis and confocal fluorescence micro-spectroscopy, allowing the observation of the spatiotemporal formation of intermediates and coke species during the MTO and ETO conversions. It was observed that rapid deactivation at elevated temperatures was due to the fast formation of aromatics at the periphery of the H-ZSM-5 crystals, which are transformed into more poly-aromatic coke species at the external surface, preventing the diffusion of reactants and products into and out of the H-ZSM-5 crystal. Furthermore, we were able to correlate the operando UV/Vis spectroscopy results observed during catalytic testing with the single crystal in situ results.
authors.affiliation: Centre for Catalysis and Sustainable Chemistry, DTU Chemistry, B. 207, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark).
authors.forename: Emily C
authors.initials: EC
authors.lastname: Nordvang
authors.affiliation: Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht (The Netherlands).
authors.forename: Elena
authors.initials: E
authors.lastname: Borodina
authors.affiliation: Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht (The Netherlands).
authors.forename: Javier
authors.initials: J
authors.lastname: Ruiz-Martínez
authors.affiliation: Centre for Catalysis and Sustainable Chemistry, DTU Chemistry, B. 207, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark).
authors.forename: Rasmus
authors.initials: R
authors.lastname: Fehrmann
authors.affiliation: Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht (The Netherlands). b.m.weckhuysen@uu.nl.
authors.forename: Bert M
authors.initials: BM
authors.lastname: Weckhuysen
keywords: UV/Vis spectroscopy; fluorescence microscopy; heterogeneous catalysis; methanol-to-olefins; zeolites