ADSORPTION CHARACTERISTICS OF MOLECULAR-SIEVING CARBONS PRODUCED FROM COAL AND PHENOL-FORMALDEHYDE RESIN MODIFIED WITH VARIOUS ORGANIC-SUBSTANCES

Molecular sieving carbons (MSCs) were produced by simply carbonizing a mixture of coal-phenolformaldehyde (PF) resin which was modified by organic substances such as coal pitches, anthracene, dihydroanthracene and acenaphthylene. By changing the carbonization temperature as well as the mixing ratio of coal, PF - resin, and organic substances we could prepare MSCs with sharp pore distributions around 0.37 to 0.44 nm in pore diameter. The possibility of using the MSCs for separation of gaseous mixtures of (1) C3H8-C3H6, (2) 1-C4H8-i-C4HB, and (3) CO2-CH4 was examined from the viewpoint of adsorption isotherm and adsorption rate. We could successfully prepare MSCs that separate each gas mixture by the difference in adsorption amounts. We could also prepare MSC whose intraparticle diffusivity for CO2 is 40 times larger than that for CH4. The separation efficiencies of the MSCs for the above gas mixtures were well correlated with the size and shape of the gas molecules to be separated and the average size and the dispersion of pore distribution curves of the MSCs.