English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
  Methanol synthesis over Cu–ZnO aggregates supported on carbon nanotubes

Großmann, D., Dreier, A., Lehmann, C. W., & Grünert, W. (2015). Methanol synthesis over Cu–ZnO aggregates supported on carbon nanotubes. Applied Catalysis A, 504, 351-360. doi:10.1016/j.apcata.2015.02.031.

Item is

Files

show Files

Locators

show

Creators

show
hide
 Creators:
Großmann, Dennis1, Author
Dreier, Axel2, Author           
Lehmann, Christian W.2, Author           
Grünert, Wolfgang1, Author           
Affiliations:
1Lehrstuhl für Technische Chemie, Ruhr-Universität Bochum, Postfach 102148, 44780 Bochum, Germany, ou_persistent22              
2Service Department Lehmann (EMR), Max-Planck-Institut für Kohlenforschung, Max Planck Society, ou_1445625              

Content

show
hide
Free keywords: Methanol synthesis; Cu/ZnO; Carbon nanotubes; Metal–substrate interaction; Alloying; SMSI model
 Abstract: Methanol synthesis was studied with catalysts containing Cu and ZnO in the interior space or on the exterior surface of multi-walled carbon nanotubes (CNTs) and were activated by different procedures – reduction in dilute H2 at 513 K with or without subsequent exposure to 10% CO/H2 at 673 K for 30 min. Characterization of the transition-metal species after these treatments by XRD and XAFS revealed striking differences. After mild reduction, XRD reflections related to Cu were missing or were of weak intensity, which could be assigned to very low primary particle sizes as detected by EXAFS. After treatment in CO/H2, reflections arising from alloy phases were obtained for all samples while non-alloyed Cu, although observed by EXAFS, escaped detection by XRD due to small primary particle sizes. Reduction of Zn2+ to Zn(0) was revealed by ZnK XANES only for some samples, which qualifies Zn(0) as a minority oxidation state for the remaining ones. Based on the XANES evidence, a new feature in ZnK EXAFS developing after CO/H2 treatment was interpreted as arising from either alloying or from an SMSI-type interaction of ZnO1−x entities with Cu nanoparticle surfaces. The catalysts exhibited very different productivities and responses to the CO/H2 treatment. In terms of specific activity (related to m2 Cu), the better samples achieved a multiple of the performance shown by a commercial reference, but suffered from insufficient stability. By contrast, such stability was demonstrated for a catalyst containing Cu/ZnO hosted in SBA-15. A catalyst series based on narrow CNTs previously functionalized by thermal shocks in flowing air stood out due to poor performance for unknown reasons. Due to these uncertainties, the data does not permit clear conclusions on the oxidation state of Zn in the promoting interaction with Cu although the general trends favor Zn2+ over Zn(0).

Details

show
hide
Language(s): eng - English
 Dates: 2015-02-162014-10-102015-02-182015-02-262015-09-05
 Publication Status: Published in print
 Pages: 10
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1016/j.apcata.2015.02.031
 Degree: -

Event

show

Legal Case

show

Project information

show

Source 1

show
hide
Title: Applied Catalysis A
  Other : Appl. Catal. A
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: Amsterdam : Elsevier
Pages: - Volume / Issue: 504 Sequence Number: - Start / End Page: 351 - 360 Identifier: ISSN: 0926-860X
CoNE: https://pure.mpg.de/cone/journals/resource/954925567761