Carbon molecular sieve adsorbents prepared from activated carbon and useful for propylene-propane separation

A process to prepare a carbon molecular sieve adsorbent composition comprising:

• depositing polymer on an activated carbon, the activated carbon comprising micropores having, as a whole, an effective micropore size greater than 6 Angstroms, wherein the polymer is deposited in or around the micropores, the deposition being performed by either:
• (1) impregnating the activated carbon with at least one monomer and then polymerizing the at least one monomer such that the polymer is formed;
• or
• (2) impregnating the activated carbon with at least one partially polymerized monomer and allowing or facilitating completion of polymerization of the at least one partially polymerized monomer after impregnation such that the polymer is formed;
• carbonizing the activated carbon and the deposited polymer together at a temperature of from 400° C. to 1000° C. to form a modified activated carbon having, as a whole, micropores that have an effective micropore size ranging from greater than 4.3 Angstroms to 6 Angstroms;
• and
• annealing the modified activated carbon under an inert atmosphere and at a temperature ranging from 1000° C. to 1500° C. to form the carbon molecular sieve adsorbent composition having:
• an effective micropore size of from 4.0 Angstroms to 4.3 Angstroms.