Porosity development during steam activation of carbon foams from chemically modified pitch
[EN] The steam activation of carbon foams obtained after thermo-oxidation treatment of coal tar pitch using inorganic acids (H2SO4 and HNO3), and subsequent low pressure foaming process without stabilization step, was investigated. The characterization of the activated carbon foams showed a strong dependence of the final structure of these materials from the chemical composition of the pitch precursor. This was related to the conditions of thermo-oxidation pre-treatment with inorganic acids, used to modify the composition of the initial pitch. In both cases carbon foams with uniform open cell structures were obtained, although they showed very different properties. When nitric acid was used in the initial thermo-oxidative treatment, the steam activation process of the carbon foam proceeded to a larger extent; the porosity parameters of this sample are twice higher than those obtained when using sulfuric acid. This was attributed to the catalytic effect of H2SO4 during the foaming step, which leads to the formation of dense carbon foams with highly ordered structure as inferred from XRD. At converse, densification of the carbon foam did not occur when using nitric acid in the initial thermo-oxidative treatment; the resulting material displayed labile surface groups decomposing at moderate temperatures, as well as an incipient microporosity, which further increased during the steam activation.
| Main Authors: | , , , , , , |
|---|---|
| Format: | artículo biblioteca |
| Language: | English |
| Published: |
Elsevier
2012-05
|
| Subjects: | Carbon foams, Pore structure, Thermo-oxidation treatment, Water steam activation, |
| Online Access: | http://hdl.handle.net/10261/98828 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|