II International Symposium on Carbon for Catalysis ABSTRACTS

PP-<strong>II</strong>-4
ON THE PREPARATION OF HIGH-DENSITY AND STRONG CARBON
NANOFIBER SUPPORT BODIES
Bitter J.H., van der Lee M.K., van Dillen A.J., Geus J.W., de Jong K.P.
Utrecht University, Debye Institute, Inorganic Chemistry and Catalysis, Utrecht, The Netherlands
e-mail: J.H.Bitter@chem.uu.nl
Introduction
Two important pre-requisites have to be balanced for a given catalyst support material: a
high bulk density and a high porosity. High bulk density, i.e, mass per reactor volume, results
in a more efficient use of the reactor volume and is therefore economically favorable above
low density supports. On the other hand, the porosity i.e., accessibility is important in order to
avoid mass transport limitations.
Nowadays, new support materials, such as carbon nanofibers (CNF) are available. The
properties of CNF potentially surpass those of conventional oxidic supports such as silica and
alumina [1,2]. Carbon nanofibers are chemically inert, pure and mechanically strong and thus
suitable as catalytic support material. The CNF-bodies consist of entangled individual carbon
nanofibers, which are formed during the catalytic growth via decomposition of CO and H 2 on
Ni/SiO 2 growth catalysts. An ongoing discussion on the suitability of CNF as catalyst support
relates to their claimed low bulk-density.
In this contribution, we show that for CNF supports the density and the porosity can be
tuned. The metal loading of the growth catalyst and the growth time of the CNF-bodies are
key factors in that respect. Moreover it is shown that these materials hold great potential as
catalyst support in slurry, fixed and fluid bed applications.
Results and Discussion
CNF were grown from 5 wt% Ni/SiO 2 and 20 wt% Ni/SiO 2 . SEM investigations showed
that after CNF growth the formed CNF bodies were enlarged replicates of the original
macroscopic Ni/SiO 2 particles. Both CNF bodies showed well defined individual fibers on the
outside of the bodies. However the CNF bodies grown from 20 wt% Ni are densely packed on
the inside and the fibers are highly entangled; individual fibers were difficult to observe. The
bodies grown from the 5 wt% Ni on the other hand are more open on the inside and the
straight individual fibers are clearly visible. This can be explained by the growth mode of the
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