Al. Cabrera et al., PREPARATION OF CARBON MOLECULAR-SIEVES .1. 2-STEP HYDROCARBON DEPOSITION WITH A SINGLE HYDROCARBON, Carbon, 31(6), 1993, pp. 969-976
A process is described for preparing a carbon molecular sieve that is
suitable for the kinetic separation of gases, such as oxygen from nitr
ogen. The process involves modifying a carbon support, having a majori
ty of micropores with an effective pore size of about 4.5 to 20 angstr
om, using a two-step process in which the sieve is contacted with two
different concentrations of a volatile carbon-containing organic compo
und. The concentration of the carbon-containing compound used in the f
irst step is larger than that in the second step, so that the pore ope
nings of the micropores of the support are narrowed successively in tw
o distinct steps without excessively filling the micropores themselves
.