Ni/SiO2 promoted growth of carbon nanofibers from chlorobenzene: Characterization of the active metal sites

Mark A. Keane, Gary Jacobs, Patricia M. Patterson

Research output: Contribution to journalArticle

Abstract

The temporal changes to supported Ni sites during the growth of graphitic carbon nanofibers (GCNs) via the decomposition of chlorobenzene over Ni/SiO2 at 873 K have been investigated. The reaction of chlorobenzene with hydrogen also generated benzene, via catalytic hydrodechlorination, as the principal competing reaction. Reaction selectivity was found to be time dependent with a switch from a preferential hydrodechlorination to a predominant decomposition that generated an increasingly more structured carbon product over prolonged time-on-stream. These findings are discussed in terms of Cl/catalyst interaction(s) leading to metal site restructuring, the latter manifest in a sintering and faceting of the Ni metal particles. The pressure exerted on the metal/support interface due to fiber formation was of sufficient magnitude to extract the Ni particle from the support; the occurrence of an entrapped Ni particle at the fiber tip is a feature common to the majority of GCNs with the incorporation of Ni fragments along the length of the GCN. Metal site restructuring has been probed by temperature-programmed reduction of the passivated samples, H2 chemisorption/temperature-programmed desorption (TPD) and XANES/EXAFS analyses. This restructuring serves to enhance destructive chemisorption and/or facilitate carbon diffusion to generate the resultant GCN. The nature of the carbonaceous product has been characterized by a combination of TEM-EDX, SEM, XRD and temperature-programmed oxidation (TPO). © 2006 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)576-588
Number of pages13
JournalJournal of Colloid and Interface Science
Volume302
Issue number2
DOIs
Publication statusPublished - 15 Oct 2006

Keywords

  • Carbon nanofibers
  • Chlorobenzene decomposition
  • H 2 chemisorption/TPD
  • Ni/SiO 2
  • SEM
  • TEM-EDX
  • Temperature-programmed reduction
  • XANES/EXAFS
  • XRD

Fingerprint Dive into the research topics of 'Ni/SiO<sub>2</sub> promoted growth of carbon nanofibers from chlorobenzene: Characterization of the active metal sites'. Together they form a unique fingerprint.

  • Cite this