II International Symposium on Carbon for Catalysis ABSTRACTS

OP-<strong>II</strong>-3
space velocities. The obtained coking rates are in good agreement with the values obtained
from the TEOM reactor, as shown in Fig. 1. In addition, the quality of the CNF (structure,
diameter and crystallinity) was found to be relatively independent of production scale. The
scale of the CNF production reactor is typically about 200-300 grams per batch in the fixed
bed, while it is about ten milligrams in the TEOM reactor. Thus, the present work has
demonstrated a successful up-scaling by a factor in the range 10000. In principle, a CNF
yield of 50 g/gcat can be obtained during a reaction time of 20 min at optimal conditions.
Figure 1. Coking rate as a function of
H 2 /CH 4 ratio at 580 ºC in TEOM (●) and
fixed bed reactor (×)
Figure 2: Coking rate as a function of time
at different space velocities in the fixed bed
reactor
The carbon nanofibre support used for CNF-synthesis was purified and oxidized in nitric
acid to introduce surface groups. Ni particles corresponding to 10-20% loading were
deposited on the carbon supports by employing both homogeneous deposition-precipitation
(HDP) and impregnation (incipient wetness). The catalysts are characterized by TPO, TPR
and XRD. Incipient wetness impregnation results in larger particles than HDP. The
preparation by homogeneous deposition-precipitation resulted in homogeneously distributed
Ni-particles. A mean particle size of 7 nm was found from XRD of the calcined catalyst.
Reduction is followed by synthesis in a fixed bed reactor at 650ºC using ethane or methane as
the carbon source. TEOM will be used to further reveal the kinetics of the carbon growth. The
difficulty in removing the ceramic support in the purification process has been avoided.
References
1 K.P. De Jong,, J.W. Geus, Catalysis Reviews - Science and Engineering , 42(4) (2000)
481-510
2 C. Pham-Huu, N.Keller, V.V. Roddatis, G.Mestl, R.Schlögl, M.J. Ledoux, Phys. Chem.
Chem. Phys., 4, (2002), 514-521
100