Preperation, characterization and utilization of palladium doped pan-based activated carbon fibers /
Baş, Serkan (2005) Preperation, characterization and utilization of palladium doped pan-based activated carbon fibers /. [Thesis]
Wet-spun poly (acrylonitrile) fibers were stabilized at 200 °C for 1, 2, 3, 4, 5 hours and 300 °C for 0.5, 1, 2 hours under an air atmosphere. Carbon fibers were investigated in terms of functional groups at the surface and surface area changes at different carbonization temperatures, 500°C, 600°C, 700°C, 800°C, 900 °C, 1000 °C. After this, all carbon fibers were chemically activated with aluminium chloride (AlCl₃) and carbon dioxide (CO₂). Fourier Transformation Infrared Spectra and Scanning Electron Microscopy images of the chemically activated carbon fibers were measured to highlight possible changes on the surface. The highest surface area was obtained for the carbon fibers that was stabilized at 300°C for and carbonized at 600°C as 135.68 m²/g. Activation of fibers increased the surface area of fibers activated at 800°C under a CO₂ atmosphere for 0.5 and 1 hour. After the activation of fiber at 800°C for 0.5 and 1 hour and at 900°C for 1 hour and with AlCl₃/Et₂O, the highest surface area was obtained for the carbon fiber stabilized at 300°C, carbonized at 800°C and activated for 1hour as 189.60 m²/g. Non-activated CFs had microporous surface which was converted to macroporous surface after activation by CO₂. However, longer activation times created more ordered graphitic layers. FT-IR spectra of almost all samples showed two major peaks near ̃1200cm-1 and ̃1600cm-1 that belonged to =C-H and -C=C-, respectively. Although some fibers contains -C-N groups these groups vanished after activation. After 5%Pd (by wt) was loaded by NaBH₄ reduction method onto carbon fibers carbonized at 800°C and stabilized at 300°C for 1 hour, cyclohexane was dehydrogenated in microautoclaves at 350°C in a differential scanning calorimeter system. Two main endothermic peaks were observed in DSC thermograms until 350°C. Chemical compounds produced after dehydrogenation experiments over 5%Pd/CF were analyzed in GC-MS. Cyclohexene, 1- methyl-cyclopentene, 1,3,5-trimethylbenzene, 3-methylcyclohexene, decanal, 1-hexanol were some of the compounds observed.
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