Browsing by Author "Moreira, Ivo"
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- Catalytic properties of carbon materials for wet oxidation of anilinePublication . Gomes, Helder; Machado, Bruno; Ribeiro, Andreia; Moreira, Ivo; Rosário, Márcio; Silva, Adrián; Figueiredo, José; Faria, JoaquimA mesoporous carbon xerogel with a significant amount of oxygen functional groups and a commercial activated carbon, were tested in the catalytic wet air oxidation of aniline at 200 ◦C and 6.9 bar of oxygen partial pressure. Both carbon materials showed high activity in aniline and total organic carbon removal, a clear increase in the removal efficiency relatively to non-catalytic wet air oxidation being observed. The best results in terms of aniline removal were obtained with carbon xerogel, an almost complete aniline conversion after 1 h oxidation with high selectivity to non-organic compounds being achieved. The materials were characterized by thermogravimetric analysis, temperature programmed desorption, N2 adsorption and scanning electron microscopy, in order to relate their performances to the chemical and textural characteristics. It was concluded that the removal efficiency, attributed to both adsorption and catalytic activity, is related to the mesoporous character of the materials and to the presence of specific oxygen containing functional groups at their surface. The effect of catalytic activity was found to be more important in the removal of aniline than the effect of adsorption at the materials surface. The results obtained indicate that mesoporous carbon xerogels are promising catalysts for CWAO processes.
- Catalytic properties of carbon xerogels for wet oxidation of anilinePublication . Machado, Bruno; Ribeiro, Andreia; Moreira, Ivo; Rosário, Márcio; Gomes, Helder; Figueiredo, José; Faria, JoaquimThe main objective of this work was to develop carbon materials suitable to be used efficiently in catalytic wet air oxidation (CWAO) processes. Accordingly, carbon xerogels with different mesoporous surface area and chemistry were prepared by the conventional sol-gel approach and tested in the CWAO of aniline at 200ºC and 6.9 bar of oxygen partial pressure. The developed materials showed high activity in aniline and total organic carbon removal, a clear increase in the removal efficiency relatively to non-CWAO being observed. At 200ºC, almost complete aniline conversions were obtained after one hour oxidation with high selectivity to non-organic compounds. The materials were characterized by thermogravimetric analysis, N2 adsorption and scanning electron microscopy, in order to relate their efficiency to the chemical and textural characteristics. It was concluded that the removal efficiency increases with the mesoporous character of the materials and with the concentration of oxygen containing functional groups at their surface. The results obtained indicate that mesoporous carbon xerogels are promising catalysts for CWAO processes.
- Textural and chemical properties of carbon xerogels for the catalytic wet air oxidation of anilinePublication . Machado, Bruno; Ribeiro, Andreia; Moreira, Ivo; Rosário, Márcio; Silva, Adrián; Gomes, Helder; Figueiredo, José; Faria, JoaquimPrevious works reporting the use of carbon materials in the oxidative treatment of aromatic compounds and of nitrogen containing compounds seem to indicate that their catalytic activity is intimately related to their surface chemistry and porous texture [1- 3]. In this work we prepared a mesoporous carbon xerogel (CX) material with a significant amount of oxygen functional groups and tested it in the Catalytic Wet Air Oxidation (CWAO) of aqueous aniline solutions. A commercial activated carbon (ROX, from Norit) was used as standard for comparison purposes. The results will have predictive value in establishing relationships between structure and catalyst efficiency in CWAO.