| Resumo: |
In this project, in order to overcome the problems related to the high mass transfer resistances associated to microporous activated carbons, we intend to prepare mesoporous carbons by the template technique, using nanostructured silica samples (e.g. SBA-15) as starting material. According to the literature, carbon materials with surface areas identical to those of activated carbons may be obtained. On the other hand, the surface chemistry of these materials can be modified by appropriate chemical and thermal treatments, similarly to activated carbons, which is important in order to optimize its performance as adsorbents or catalysts. Additionally, other types of mesoporous carbons will be prepared (e.g. xerogels, commercial activated carbons subjected to controlled gasification). On the other hand, metals like Mn and Fe can be introduced in the catalyst by anchorage of suitable metal complexes on carbon by covalent bonding with the surface oxygenated groups, expecting to have some advantages in terms of catalyst stability, relatively to the conventional processes. In this context, metalloporphyrin complexes, which have well known catalytic properties for oxidation in homogeneous systems, are promising species. The utilization of mesoporous carbons is also advantageous in this catalysts preparation stage, since the mentioned complexes are large molecules. Moreover, an appropriate carbon surface chemistry is decisive for an efficient anchorage of the metalloporphyrins selected. Therefore, this aspect will be also studied.
Summarizing, the main objectives of this project are:
1) Preparation, functionalization and characterization of mesoporous carbons, mainly those obtained by the silica template technique.
2) Anchorage of Fe and Mn porphyrin complexes on the surface of the various carbon materials in order to evaluate the influence of the surface chemistry.
3) Evaluation of the carbon and hybrid materials as adsorbents and ozonation catalysts of selected organ  |
Resumo
In this project, in order to overcome the problems related to the high mass transfer resistances associated to microporous activated carbons, we intend to prepare mesoporous carbons by the template technique, using nanostructured silica samples (e.g. SBA-15) as starting material. According to the literature, carbon materials with surface areas identical to those of activated carbons may be obtained. On the other hand, the surface chemistry of these materials can be modified by appropriate chemical and thermal treatments, similarly to activated carbons, which is important in order to optimize its performance as adsorbents or catalysts. Additionally, other types of mesoporous carbons will be prepared (e.g. xerogels, commercial activated carbons subjected to controlled gasification). On the other hand, metals like Mn and Fe can be introduced in the catalyst by anchorage of suitable metal complexes on carbon by covalent bonding with the surface oxygenated groups, expecting to have some advantages in terms of catalyst stability, relatively to the conventional processes. In this context, metalloporphyrin complexes, which have well known catalytic properties for oxidation in homogeneous systems, are promising species. The utilization of mesoporous carbons is also advantageous in this catalysts preparation stage, since the mentioned complexes are large molecules. Moreover, an appropriate carbon surface chemistry is decisive for an efficient anchorage of the metalloporphyrins selected. Therefore, this aspect will be also studied.
Summarizing, the main objectives of this project are:
1) Preparation, functionalization and characterization of mesoporous carbons, mainly those obtained by the silica template technique.
2) Anchorage of Fe and Mn porphyrin complexes on the surface of the various carbon materials in order to evaluate the influence of the surface chemistry.
3) Evaluation of the carbon and hybrid materials as adsorbents and ozonation catalysts of selected organic compounds (e.g. dyes, aniline, oxalic acid). |