Proceso para la obtención de tamices moleculares de carbón

La presente invención describe un proceso en el que un precursor de carbón adecuado, como por ejemplo fibras de carbón, fibras de carbón activadas, carbones activos etc. se someten a un calentamiento en un horno microondas en condiciones de temperaturas elevadas y atmósfera inerte. Las particulares características de este calentamiento en microondas producen cambios en la textura porosa de los precursores en forma tal que los transforma en materiales que pueden ser denominados tamices moleculares de carbón. Los tamices moleculares así obtenidos presentan una selectividad para la separación de mezclas O2/N2, CO2/CH4, comparable a la de otros tamices moleculares de carbón obtenidos mediante otros métodos más complejos y costosos que el aquí descrito.Peer reviewe

New acrylic monolithic carbon molecular sieves for O2/N2 and CO2/CH4 separations

8 pages, 5 figures, 4 tables.-- Available online Dec 20, 2005.The modification of activated carbon fibres prepared from a commercial textile acrylic fibre into materials with monolithic shape using phenolic resin as binder was studied. The molecular sieving properties for the gas separations CO2/CH4 and O2/N2 were evaluated from the gas uptake volume and selectivity at 100 s contact time taken from the kinetic adsorption curves of the individual gases. The pseudo-first order rate constant was also determined by the application of the LDF model. The samples produced show high CO2 and O2 rates of adsorption, in the range 3–35 × 10−3 s−1, and in most cases null or very low adsorption of CH4 and N2 which make them very promising samples to use in PSA systems, or similar. Although the selectivity was very high, the adsorption capacity was low in certain cases. However, the gas uptake in two samples reached 23 cm3 g−1 for CO2 and 5 cm3 g−1 for O2, which can be considered very good. The materials were heat-treated using a microwave furnace, which is a novel and more economic method, when compared with conventional furnaces, to improve the molecular sieves properties.The authors are grateful to the Fundação para a Ciência e a Tecnologia (Portugal), the European Regional Development Fund (FEDER) and Scientific and Technological Cooperation Program GRICES/CSIC (2004/5_4.1.1) for financial support.Peer reviewe