Progress of Cryogenics and Isotopes Separation , ISSN: 1582-2575
2001, Volume 4, Issue 7+8

Synthesis of Carbon Molecular Sieves by Benzene Pyrolysis Over Microporous Carbon Materials

Abstract

In the present work an effort has been made to develop suitable process conditions for synthesis carbon molecular sieves (CMS) from the locally available bituminous and walnut shell char (CH, CW). The process involves modifying a carbon support having a majority of micropores with an effective pore size of about 4 to 25 Å. The sieves are contacted with different concentration of a volatile carbon containing organic compound. The char was crushed, milled and agglomerated with starch and pitch as the binders, and then carbonized in nitrogen atmosphere at 650-750^oC for about 60 minutes.

In order to narrow down the pore mouth sizes, benzene were cracked at 650- 800^oC, for 10 to 60 minutes to facilitate then deposition of coke on the carbon support. All the products were characterized by analysis of pore size distribution, volume of pores, surface area and adsorption data. The best carbon molecular sieve was obtained for feed benzene entrance in N₂ of 3,5×10^-4 g/ml, cracking time of 30 minutes and pyrolysis temperature of 800^oC. These carbon molecular sieves are suitable for gas separations. Their performance was judged by the kinetic separation of Ar-O₂ mixture. Besides their application to gas separation, these CMS materials are receiving increased attention as catalysts.