Espumas de carbono: síntese, caracterização e aplicação
Carbon foams are materials with a porous structure mainly composed of macropores, which present high specific area, light weight, thermal and electrical conductivity, high thermal stability, being applied as adsorbents, electrodes, supports for catalysts, thermal insulation at high temperatures,...
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| Formaat: | doctoralThesis |
| Taal: | pt_BR |
| Gepubliceerd in: |
Brasil
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| Online toegang: | https://repositorio.ufrn.br/jspui/handle/123456789/27361 |
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| Samenvatting: | Carbon foams are materials with a porous structure mainly composed of macropores,
which present high specific area, light weight, thermal and electrical conductivity, high
thermal stability, being applied as adsorbents, electrodes, supports for catalysts,
thermal insulation at high temperatures, among others. Several methods and raw
materials have been used to synthesize carbon foams. These include petroleum
sources and derivatives, but the limit and scarcity of these materials makes it
necessary to search for raw materials from renewable sources or biomass. For this
reason, this research had the objective of synthesizing carbon foams using sucrose as
the carbon source and the aluminum, iron and silver nitrates as blowing agents. In
addition, carbon foams using montmorillonite as reinforcing agent were also produced.
Finally, we studied the substitution of the traditional sucrose carbon source for glycerol
(biomass) and the materials were applied to remove CO2. Therefore, a methodology
known for obtaining these materials called blowing of the carbon precursor through the
addition of chemical agents was adopted. Morphology, structure, texture properties,
mechanical strength and CO2 adsorption capacity at 35 °C were evaluated in the
obtained samples. It is observed that the iron, silver and aluminum nitrates were
efficient as blowing agents in the production of carbon foams with structure of
interconnected pores and high porosity in the 90% range, the samples have a good
BET specific surface, especially were synthesized with aluminum nitrate (EsAl) and
iron nitrate (EsFe) with values of 602 and 380 m2
/g, respectively. The addition of the
reinforcing agent (montmorillonite) in the production of carbon foams shows a trend in
improving the mechanical strength of the EsAlAr foams (2.28 MPa) attributed good
dispersion of the reinforcement on the surface of the samples. Efficient substitution of
up to 50% sucrose content by glycerol in the synthesis of carbon foams shows an
increase in the BET specific surface as the proportion of glycerol in the foams
increases. All samples synthesized with iron nitrate present a more ordered structure.
The capture of CO2 at 35°C is efficient in the foams obtained, highlighting in the
samples synthesized with aluminum nitrate (EsAl) and in samples with glycerol
proportions of 10 and 30% (EsGl10 and EsGl30) with CO2 capture value of 5.3 mmol.g1. |
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