Preparation of molecular sieving carbon from waste resin by chemical vapor deposition

Molecular sieving carbons (MSCs) were prepared from carbonized phenol-formaldehyde resin wastes by the chemical vapor deposition (CVD) of the pyrolyzed carbon from hydrocarbon species. The pore size of the MSCs could be controlled in the range 0.37-0.42 nm by changing the hydrocarbon species pyrolyzed, the pyrolyzing temperature, and the processing time. It is shown that some of the MSCs have an excellent selectivity for separating CO₂ and CH₄, and others for separating C₃H₈ and C₃H₆. As the mechanism for controlling the pore size during CVD processing, we elucidated that the adsorption of hydrocarbon molecules first takes place on the pore surface and then the adsorbed hydrocarbons pyrolyze into carbon. Therefore, the pore size of the MSC can be adjusted by controlling the amount hydrocarbon adsorbed on the phenol-formaldehyde resin char.