Pore size control through benzene vapor deposition on activated carbon

Carbon adsorbents are considered as prime material to separate oxygen and nitrogen in PSA process. It is known that selectivity of carbon adsorbents can be added by adjusting pore size on the adsorbents. Among many treatment methods, chemical vapor deposition method was selected and benzene was used as a chemical agent. Activated carbons were heated at 5 °C/min and 10 °C/min in inert condition. The peak temperature at 700 °C and 800 °C was maintained while activated carbons were treated with benzene vapor. Inert condition was given as laminar and turbulent flow conditions. Pore size distribution results investigated by adsorption of various gases including CO₂ (3.3 Å), n-butane (4.3 Å) and iso-butane (5.0 Å), assured of the pore constriction or heightened energy barrier on the pore opening. The nitrogen diffusivity and the selectivity of treated samples are inversely proportioned. That means selectivity comes out, when pore mouth is well blocked, not to admit the nitrogen molecules.