Herringbone-type carbon nanofibers

The multiwalled nanotubes as well as the herringbone type carbon nanofibers were synthesized in-house in a quartz glass fluidized bed reactor via chemical vapor deposition (CVD). The method is described in detail elsewhere.19 The platelet nanofibers, in contrast, were purchased from the company FutureCarbon GmbH (Bayreuth, Germany). 

FIGURE 2.1 Cobalt functionalized (a) platelet type carbon nanofibers, (b) herringbone type carbon nanofibers, and (c) carbon multiwalled nanotubes. 

Harutyunyan et al. reported for tubular and herringbone type carbon nanofibers... 

There are mainly three types of carbon nanofibers the herringbone in which the graphene layers are stacked obliquely with respect to the fiber axis the platelet in which the graphene layers are perpendicular to the fiber axis and the tubular in which the graphene layers are parallel to the growth axis [55],... 

The potential of carbon nanomaterials for the Fischer-Tropsch synthesis was investigated by employing three different nanomaterials as catalyst supports. Herringbone (HB) and platelet (PL) type nanofibers as well as multiwalled (MW) nanotubes were examined in terms of stability, activity, and selectivity for Fischer-Tropsch synthesis (FTS). 

Concerning the Fischer-Tropsch synthesis, carbon nanomaterials have already been successfully employed as catalyst support media on a laboratory scale. The main attention in literature has been paid so far to subjects such as the comparison of functionalization techniques,9-11 the influence of promoters on the catalytic performance,1 12 and the investigations of metal particle size effects7,8 as well as of metal-support interactions.14,15 However, research was focused on one nanomaterial type only in each of these studies. Yu et al.16 compared the performance of two different kinds of nanofibers (herringbones and platelets) in the Fischer-Tropsch synthesis. A direct comparison between nanotubes and nanofibers as catalyst support media has not yet been an issue of discussion in Fischer-Tropsch investigations. In addition, a comparison with commercially used FT catalysts has up to now not been published. 

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