CHEMICAL-VAPOR-DEPOSITION OF HETEROCYCLIC-COMPOUNDS OVER ACTIVE-CARBON FIBER TO CONTROL ITS POROSITY AND SURFACE FUNCTION

The chemical vapor deposition (CVD) of some heterocyclic compounds was examined to control the porosity and surface functionality of the act ive carbon fiber (ACF). The deposition took place only on the pore wal l of the ACF, when the heterocyclic compound as the precursor and the deposition temperature were selected carefully to be thermally stable and around 700 degrees C, respectively. Moderately activated ACFs modi fied with pyridine, pyrrole, and thiophene demonstrated molecular siev ing activity for selective adsorptions of CO2/CH4 and O-2/N-2 through selective CVD. In contrast, furan decomposed at this temperature, fail ing to provide molecular sieving activity. The thermal stability of th e depositing molecules is a key factor to obtain the molecular sieving performance after CVD. Pyridine, pyrrole, and thiophene produced amor phous carbon within the pore which appears to implant the nitrogen and sulfur atoms over the surface of the ACF, respectively.