Carbon 38 (2000) 1965–1976
Comparative adsorption study on carbons from polymer
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Krisztina Laszlo , Attila Bota, Lajos Gyorgy Nagy
Department of Physical Chemistry
Budapest University of Technology and Economics
Received 4 November 1998; accepted 10 February 2000
The effect of the precursor polymer on nitrogen adsorption properties, pore size distribution and the hydrophilic/
hydrophobic character of both the pyrolyzed char and the activated carbon was studied in the case of three basically different
polymers, i.e. polyacrylonitrile, polyethyleneterephthalate and cellulose. Pyrolyzed samples were produced from these
polymers and activated by steam at 9008C. After a 50% burn-off, the pore volume and the speciﬁc surface area increase
signiﬁcantly and the pore size distribution is determined by that of the pyrolyzed char, i.e. the starting polymer. The activated
sample derived from polyacrylonitrile is microporous, while the other two carbons contain both micro- and mesopores.
Activation creates pores which are equally available for methanol and benzene and the heterogeneous surfaces become more
benzophilic in all three polymers. The N-content has limited effect on the surface properties studied. 2000 Elsevier
Science Ltd. All rights reserved.
A. Porous carbon; B. Pyrolysis, Activation; C. Adsorption; D. Surface properties
1. Introduction structure spectroscopy (XANES)  studies. The trans-
formation of nitrogen functionalities in gasiﬁcation pro-
Activated carbons with high surface area and pore cesses were recently studied in model chars [15–17].
volumes can be produced from a variety of carbonaceous Cellulose is most often applied in the form of various
materials. Polymer precursors are especially preferred lignocellulosic materials, such as coconut shells, olive
when carbon with low inorganic impurities is needed. stones, cherry stone, apricot pit, wood, etc. [18–23]. In this
Specially developed polymers are used for the fabrication paper, the pore structures and the surface properties of
of monolithic carbon, or for carbon ﬁbers [1–5]. The most pyrolyzed chars and activated carbons from three different
well studied polymer representatives are the polyacryloni- polymer precursors, i.e. the already mentioned polyacryl-
trile and the derivatives of cellulose. Polyacrylonitrile- onitrile, cellulose, and polyethyleneterephthalate are com-
based activated carbons have attracted increasing attention pared. Polyethyleneterephthalate (PET) might be a promis-
because of their excellent surface properties and adsorption ing precursor. For its wide commercial application, its
capacity, due to the nitrogen atoms contained in the basal conversion to activated carbon also offers a way of
plane structure [6–10]. The distribution of pyridinic, recycling. Polyacrylonitrile (PAN) and cellulose (CEL)
pyrrolic and quaternary nitrogen in carbons has been were studied for comparison.
studied in detail. The inclusion of nitrogen within the
graphene layers in quaternary form was originally pro-
posed on the basis of temperature controlled combustion
studies  and conﬁrmed by X-ray photoelectron spec-
troscopy (XPS) [12,13] and X-ray absorption near edge
Precursors and sample preparation
Cellulose sheets prepared from pine (Pinus silveris)
*Corresponding author. Tel.: 136-1463-1893; fax: 136-
were obtained from the Paper Research Institute, Hungary
(a-cellulose 88.3% w/w, hemicellulose 9.6% w/w,
firstname.lastname@example.org (K. Laszlo).
ash 0.5% w/w). Granulated polyethyleneterephthalate
0008-6223/00/$ – see front matter 2000 Elsevier Science Ltd. All rights reserved.