Granular carbon molecular sieves

• Published in: Carbon (New York) Vol. 32; no. 3; pp. 445 - 452
• Main Authors: Braymer, T.A., Coe, C.G., Farris, T.S., Gaffney, T.R., Schork, J.M., Armor, J.N.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1994; Elsevier Science
• Subjects: Adsorbent; Adsorbents; air separation; carbon molecular sieves; Chemistry; coconuts; Exact sciences and technology; General and physical chemistry; granules; pyrolysis; Surface physical chemistry; air separation; coconuts; pyrolysis; carbon molecular sieves; Adsorbent; granules; Characterization; Pyrolysis; Pore size; Preparation; Coconut; Experimental study; Carbon; Molecular sieve
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/0008-6223(94)90165-1

Any future carbon molecular sieve (CMS) for use in the commercial production of N 2 should have a high volumetric O 2 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°C per minute to a peak temperature of 775° to 900°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 CO 2, H 2O, or O 2 at 650° to 900°C increases the O 2 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.