II International Symposium on Carbon for Catalysis ABSTRACTS

PP-<strong>II</strong>-4
CNF from both catalysts. The
1.0
fibers grown from 20 wt% Ni have
0.8
a large diameter compared to those
grown from 5 wt% Ni. This is a
0.6
result of the more significant
0.4
sintering of the Ni particles in the
20 wt% growth catalyst as result of
0.2
0 5 10 15 20 25 30 35 40
Carbon per gram nickel
Figure 1: Schematic representation of macroscopic
bodies consisting of dense CNF growth from left to
right: Ni/SiO 2 body with cracks – growing CNF
fragmentize the body – start of large diameter
growth CNF in interior – further expansion of CNF
body.
the higher metal loading. Thicker
fibers grow in a more irregular
way, the so called rice shell
mechanism [3], resulting in a high
entanglement and high bulk density
(0.9 g/ml). Note that in the initial
stage of growth the starting
Ni/SiO 2 catalyst breaks in smaller particles as seen in SEM. Next the CNF grow in a highly
entangled way resulting in filling up the open space, i.e, forming a high density and strong
bodies. This is schematically shown in Figure 1. The thin fibers on the other hand grow in a
more straight manner resulting in an open, less entangled structure, with a low bulk density
(0.4 g/ml).
CNF-body diameter [mm]
Concluding Remarks
CNF can be prepared in high-dense bodies (bulk density 0.9 ml/g). These bodies have a
bulk crushing strength of 1.25 MPa. which gives them a great potential as a catalyst support
[4]. Both the bulk density and strength of the CNF bodies relates to the metal loading in the
Ni/SiO2 growth catalyst.
References
[1] K. P. de Jong and J. W. Geus, Catal. Rev.- Sci Eng 42, 481 (2002)
[2] P. Serp, M. Corrias, P. Kalck, Appl. Catal A: Gen, 2003;253:337-58
[3] M.S. Hoogenraad, Ph.D. thesis, Utrecht University, Utrecht, The Netherlands, (1995)
[4] M.K. van der Lee, A.J. van Dillen, K.P. de Jong and J.H. Bitter, World patent application
PCT/2005/000274
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