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  Directional freeze-cast hybrid-backbone meso-macroporous bodies as micromonolith catalysts for gas-to-liquid processes

Kim, J., Nese, V., Joos, J., Jeske, K., Duyckaerts, N., Pfänder, N., et al. (2018). Directional freeze-cast hybrid-backbone meso-macroporous bodies as micromonolith catalysts for gas-to-liquid processes. Journal of Materials Chemistry A, 2018(44), 21978-21989. doi:10.1039/C8TA07512C.

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 Creators:
Kim, Jonglack1, Author              
Nese, Valentina2, Author              
Joos, Jochen3, Author
Jeske, Kai1, Author              
Duyckaerts, Nicolas2, Author              
Pfänder, Norbert4, Author              
Prieto, Gonzalo1, Author              
Affiliations:
1Research Group Prieto, Max-Planck-Institut für Kohlenforschung, Max Planck Society, ou_2243639              
2Research Department Schüth, Max-Planck-Institut für Kohlenforschung, Max Planck Society, ou_1445589              
3Institute for Applied Materials (IAM-WET), Karlsruhe Institute of Technology (KIT), Adenauerring 20b, Karlsruhe, Germany , ou_persistent22              
4Max Planck Institute for Chemical Energy Conversion, Mülheim an der Ruhr, Germany, ou_persistent22              

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 Abstract: Materials with spatially organized and multimodal porosities are very attractive in catalysis, as they can reconcile nano-confinement effects in micro- and mesopores with fast molecular transport in wide macropores. However, the associated large pore volumes often result in low overall thermal conductivities, and thus suboptimal heat management in reactions with a high thermal signature, usually with a deleterious impact on the catalytic performance. Here we report the directional freeze-casting assembly of bimodally meso-macroporous micromonolithic bodies with a hybrid backbone composed of intimately bound carbon nanotubes (CNTs) and ZrOx–Al2O3 nanocrystals. A honeycomb-shaped and axially oriented macroporous architecture is achieved through the use of zirconium acetate as an ice growth modulator. (S)TEM and EDX nanospectroscopy show that the nanoscale intimacy between the CNT and oxide backbone components depends on the synthesis route of the mother slurry. As revealed by X-ray tomography, coupled to quantitative image analysis, not only the macrochannel size and wall thickness, but also the extent of axial heterogeneities in macropore diameter and spatial orientation depend on the axial temperature gradient rate during casting. The structured bodies are explored as carriers for cobalt-based catalysts for the Fischer–Tropsch production of synthetic hydrocarbons from syngas, of central significance in intensified X-to-liquid processes. Hybrid CNT-Al2O3 backbone micromonolith catalysts show a high selectivity to C3–8 olefins, owing to the fast evacuation of these primary reaction products from the metal active sites through the directional macropore system. Remarkably, the high olefin selectivity is maintained up to higher operating temperatures compared to reference catalysts based on all-oxide supports, due to a higher effective thermal conductivity which inhibits the development of hotspots under industrially relevant operating conditions.

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Language(s): eng - English
 Dates: 2018-08-022018-08-202018-09-112018-11-28
 Publication Status: Published in print
 Pages: 12
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1039/C8TA07512C
 Degree: -

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Title: Journal of Materials Chemistry A
  Abbreviation : J. Mater. Chem. A
Source Genre: Journal
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Publ. Info: Cambridge, UK : Royal Society of Chemistry
Pages: - Volume / Issue: 2018 (44) Sequence Number: - Start / End Page: 21978 - 21989 Identifier: ISSN: 2050-7488
CoNE: https://pure.mpg.de/cone/journals/resource/2050-7488