2001, Volume 4, Issue 7+8
Synthesis of Carbon Molecular Sieves by Benzene Pyrolysis Over Microporous Carbon Materials
1 National R&D Institute for Cryogenics and Isotopic Technologies, Ramnicu Valcea
2 University of Sydney, Department of Chemical Engineering, Australia
*Corresponding author: Elena David, e-mail: email@example.comPublished: October 2001
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 650-750oC for about 60 minutes.
In order to narrow down the pore mouth sizes, benzene were cracked at 650- 800oC, 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 800oC. 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.
Carbon molecular sieves, coal, benzene, Ar/O2 separation.
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