Materiales de carbono micro-mesoporosos obtenidos mediante nanomoldeo

Resumen

[EN] The main aim of the present work is to develop new synthetic methods that allow the preparation of carbon materials with an ordered structure and bimodal porosity in the micro-mesopore range. To this end, three different approaches, using nanocasting as pore control technique, have been followed: i) microporosity development, by physical or chemical activation, in ordered mesoporous carbons ii) replication of micro-mesoporous alumininosilicates by chemical vapor deposition and iii) "one-pot" synthesis of hierarchical carbons by co-assembly of silicates, block copolymers and carbon precursors derived from biomass. In the three mentioned methods it was performed a systematic study of the preparation variables and they have been related with the porosity and structure of the obtained carbons. Physical activation of ordered mesoporous carbons results in a considerable microporosity increase and a collateral mesoporosity widening. In the case of chemical activation, microporosity increases with increasing activation temperature and/or activating agent proportion; nevertheless, at strong activation conditions it causes great deterioration of the ordered mesoporous network. To solve this problem, a novel method involving the direct activation of the carbon/template composite was proposed. Thus, carbons with a hierarchical porosity and surface areas up to 1700 m2/g were achieved whilst the ordered mesostructure was preserved. The second route accomplishes a real control of both the porosity and the structure. Hierarchical aluminosilicates with microporous core and mesoporous shell were prepared. Optimum infiltration conditions were established in order to correctly infiltrate both micro and mesoporosity of the prepared templates. Using this strategy carbons with core/shell structure and surface areas from up to 1323 m2 /g were obtained. In the third route the interactions between the structure directing agent, the silica precursor and the carbon precursor were adjusted by varying synthesis conditions of a sol-gel process in order to obtain hierarchical carbons. The main advantage of this route is its simplicity since it is a “one-pot” process.