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Activated carbon fibers originated from viscose was brominated in the dibromine solution. An active surface precursor with 1.0 mmol of bromine per gram of carbon fibers was obtained. The bromine groups are capable for a further replacement, e.g. for amines residues. The thermochemical properties of the synthesized samples were studied. The rules of the surface layer bromination were discussed within the results of the thermal and chemical analysis. Two types of bromine groups on the carbon fiber surface were determined by the thermal desorption. These groups were associated with different centers situated on the accessible surface or placed in tight nanoscale pores. The reason of such distribution was the bromination that producing groups which binding strength varies and the effect of configuration factor. This factor limits the thermal desorption of various gaseous molecules which were formed and released during the thermal decomposition of grafted functionalities and sorbed by the samples with small nanosized pores. The use of the precursor route shows that the interface covered with from 0.62 to 0.95 mmol/g of the residual amine functional groups can be prepared.

Activated carbon fibers (ACFs) made from polyacrylonitrile and viscose were treated with the sulfur vapor at the temperatures of 500–800 °C in an argon flow. Obtained materials were oxidized by 30% H 2 O 2 water solution in order to convert S-containing surface moieties into SO 3 H-groups. The samples were studied using Boehm titration, thermogravimetric analysis and temperature-programmed desorption with a mass spectrometric registration of gaseous desorption products. According to obtained data, the surface layer of synthesized samples contains grafted SO 3 H-groups and different functional groups formed at the carbon oxidation. The decomposition of SO 3 H-groups occurs in the temperature range of 75–590 °C. Two peak maxima at 200±30 °C and 300±30 °C were registered on all SO 2 desorption profiles. These maxima are assigned to two forms of surface SO 3 H groups having a different chemical environment. Testing of the catalytic activity shows that SO 3 H-functionalized carbon fibers are high active in the model reaction of propan-2-ol dehydration. The total conversion of propan-2-ol to propene is observed at 145–220 °C. The lowest temperature of total conversion was registered for the ACFs prepared from polyacrylonitrile being treated with the sulfur vapor at 500 °C. All SO 3 H-functionalized samples maintain their activity after repeated use.