GRANULAR CARBON MOLECULAR-SIEVES

Any future carbon molecular sieve (CMS) for use in the commercial production of N2 should have a high volumetric O2 equilibrium capacity. We developed a procedure for producing a high capacity coconut shell char that can be converted into a high capacity CMS for air separation. Granules of coconut shell char are heated in flowing inert gas at about 2 to 12-degrees-C per minute to a peak temperature of 775-degrees to 900-degrees-C. After holding from 1 to 8 hours, the char is cooled in an inert gas atmosphere. The granular char thus produced has an oxygen capacity in excess of 8.0 cc/cc. Contacting the char with an oxidizing atmosphere containing CO2, H2O, or O2 at 650-degrees to 900-degrees-C increases the O2 capacity to greater than 9.0 cc/cc. The coconut shell char can be converted to a CMS by treatment with a volatile carbon-containing organic compound that, when pyrolyzed, deposits carbon within the interior of the carbon granules. The granular CMS thus produced can be used in a nitrogen pressure swing adsorption column without the need for pelletization.