IJUP08 - Universidade do Porto

Mesoporous Carbons: Synthesis and Functionalization
C.A. Orge 1 , J.P.S. Sousa 1 , F. Gonçalves 1 , C. Freire 2 ,
M.F.R. Pereira 1 and J.J.M. Órfão 1
1 Laboratório de Catálise e Materiais, Departamento de Engenharia Química, Faculdade de
Engenharia, Universidade do Porto, 4200-465 Porto, Portugal.
2 REQUIMTE, Departamento de Química, Faculdade de Ciências, Universidade do Porto,
Rua do Campo Alegre, 4169-007 Porto, Portugal.
Mesoporous carbons have received a great attention due to their potential use as advanced
adsorbents and catalytic supports. Comparatively to the traditional microporous activated
carbons, the use of these materials in the aforementioned applications presents several
advantages, mainly related to its large-pore network, which makes mass transfer
limitations less significant. This is of utmost importance when dealing with bulky
molecules, such as textile dyes. On the other hand, the surface chemistry of these carbons
can be tailored to specific needs, by appropriate chemical and thermal treatments. Several
methods can be followed for preparing these materials, such as catalytic activation of
carbon precursors, template-based methods, carbonization of polymer/polymer blends and
organic cryo-, xero- and aerogels.
The present work aimed on the preparation of mesoporous carbons with large surface area,
high porosity and a controlled, narrow pore size distribution. Two main series of materials
were produced: a) carbon xerogels (CX), prepared by sol-gel condensation of resorcinol
and formaldehyde [1]; and b) templated carbons
(CMK-3), using a previously synthesised silica
(SBA-15) as template [2]. After the synthesis step,
the surface chemistry of the carbons prepared was
modified by means of gas and liquid phase
treatments, with O2 and HNO3, respectively. The
nature and amount of the surface oxygen groups
introduced by the different treatments was then
analysed by temperature-programmed desorption
(TPD) and the textural characterization of all the
carbons prepared was based on the N2 adsorption
isotherms at -196 ºC. Figure 1 shows the TPD
profiles obtained for the CX samples.
In a second phase of the work, the synthesised
carbons will be used in adsorption processes and in
the preparation of oxidation catalysts (e.g. anchored
metalloporphyrins) for the treatment of textile
effluents.
Acknowledgements: This work was partially funded by the program Investigação Científica na Pré-Graduação 2007,
(Universidade do Porto and Caixa Geral de Depósitos - project IPG58) and by Fundação para a Ciência e a Tecnologia
(POCTI/1181). FG thanks Fundação para a Ciência e a Tecnologia for the project POCI/N001/2005.
References:
[1] Mahata, N., Silva, A.R., Pereira, M.F.R., Freire, C., Castro, B., Figueiredo, J.L. (2007),
Anchoring of a [Mn(salen)Cl] complex onto mesoporous carbon xerogels, J Colloid Interf Sci 311
152-158.
[2] Fuertes, A.B. (2004), Synthesis of ordered nanoporous carbons of tunable mesopore size by
templating SBA-15 silica materials, Micropor Mesopor Mat 67 273-281.
a)
CO 2 (μmol.s -1 .g -1 )
b)
CO (μmol.s -1 .g -1 )
0.15
0.10
0.05
0.00
0 250 500 750 1000
0.9
0.6
0.3
Temperaure (ºC)
0.0
0 250 500 750 1000
Temperaure (ºC)
CX
CX-HNO 3
CX-O 2
Figure 1 – TPD spectra for the CX.
a) CO2 evolution; b) CO evolution.
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