Modification of activated carbon fiber pore structure by coke deposition

The pore structure of activated carbons can be tailored to produce carbon m olecular sieves (CMS), by vapour phase thermal decomposition of hydrocarbon s. Thermal cracking of propylene at 700 degreesC was used to deposit coke o n activated carbon fibers. Pore structure development was studied by determ ining the adsorption isotherms of N-2 at 77 K and CO2 at 298 K, while the m olecular sieving properties were investigated by the kinetic uptake curves of CO2 and CH4 at room temperature. Coke deposition resulted in the decreas e of surface area and the enhancement of molecular sieving properties durin g the early stages of hydrocarbon decomposition.