Carbon molecular sieves from hardwood carbon pellets.: The influence of carbonization temperature in gas separation properties

The influence of carbonization temperature in the preparation of hardwood carbon molecular sieves (CMS) has been studied. The textural characterization of the obtained materials included adsorption isotherms of CO(2), C(2)H(6) and n-C(4)H(10) to obtain the micropore size distribution. Adsorption kinetics of CH(4), CO(2), C(3)H(6) and C(3)H(8) were measured in all materials to determine their behavior as molecular sieves. Results confirm that the carbonization temperature of this hardwood has a very significant effect on the resulting CMS separation properties. The increase in the wood's carbonization temperature reduced the CMS micropore size distribution. Consequently, high carbonization temperatures (1000 degrees C) are required to obtain good CH(4)/CO(2) separation, while a low carbonization temperature (700 degrees C) is best for C(3)H(6)/C(3)H(8) separation. The differences in separation properties of these materials could be explained by a partial blocking of the micropore entrance produced by disorganized carbon migrating from the internal structure (chars) and by the additional binder used to prepare the CMS. (c) 2005 Elsevier Inc. All rights reserved.