II International Symposium on Carbon for Catalysis ABSTRACTS

PP-<strong>II</strong>-11
CARBON FIBROUS SORBENTS WITH CATION-EXCHANGE PROPERTIES
Khokhlova G.P., Kryazhev Yu.G. 1 , Senkevich S.I. 1
Institute of Coal and Coal Chemistry, SB RAS, Omsk, Russia
1 Institute of Hydrocarbons Processing, SB RAS, Omsk, Russia
e-mail: gkhokhlova@yandex.ru
The weak cation-exchange properties of many carbon sorbents are explained by the
presence of a certain amount of acid groups on the surface of the carbon material because of
the oxidizing reactions proceeding in the formation of the carbon structure at high
temperatures. The content of the acid groups can be increased by oxidizing modification of the
carbon material. In this case the method used determines the chemical behavior and stability of
polar groups introduced.
The purpose of the given research is comparison of various ways of the foregoing
modification of carbon sorbents. The basic criterion of an estimation of efficiency of the
process is stability of acid groups introduced at a typical ion-exchange and regeneration
treatments. In our opinion, oxidizing modification of carbon surface can give the greatest
effect in case of fibrous materials because the advanced external surface of fibers allows to
reach of the most content of polar groups. On the other hand, heat-and-mass transfer at the
carbon surface creation is facilitated by the fibrous form of carbon.
As suitable object of the research the carbon fiber based on hydrated cellulose has been
chosen. Cellulose is one of the main raw material for producing of activated carbon fibrous
materials.
In this work carbon fibrous sorbents (CFS) having cation-exchange properties were obtained
by the various ways: (i) by the low-temperature treating it with a strong oxidizing agent -
hydrogen peroxide, (ii) by carbonization of the initial cellulose material in the presence of a
modifying additives - Mo, Cr, V or W oxides (see recent communication [1]), and (iii) by
oxidation of carbon fibers with air or ozone in the absence or presence of the additives aforesaid.
For comparison, carbonization of the hydrated cellulose fiber (rayon) was performed in the
presence of ammonium chloride (the analog of serial CFS, produced at industrial conditions).
It has been shown that transitional metals compounds can catalyze activation of carbon
both with H 2 O and CO 2 , and increase the concentration of acidic groups on carbon surface.
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