Abstract

SILVA, Camila Ramos da; WALLAU, Martin  and  URQUIETA-GONZALEZ, Ernesto A.. Mesoporous carbons prepared by nano-casting with meso- or non-porous silica nanoparticles. J. Braz. Chem. Soc. [online]. 2006, vol.17, n.6, pp. 1170-1180. ISSN 0103-5053.  http://dx.doi.org/10.1590/S0103-50532006000600015.

Mesoporous carbons were obtained by sequential nano-casting using the following hard templates: (i) mesoporous silica nanospheres with MCM-41 or MCM-48 analogous structure; (ii) non-porous silica nanospheres and (iii) pyrogenic silica (Aerosil 200). These silica templates (patrix) were impregnated with sucrose, carbonized at 800 ºC under nitrogen atmosphere and finally the silica dissolved with hydrofluoric acid. It was observed that the specific surface area of the carbon matrixes can be enhanced reducing the diameter of the silica nanospheres or the distance between them by agglomeration prior to the impregnation of the silica patrix with sucrose. Mesoporous carbons with specific surface areas higher than 500 m² g^-1 were obtained using mesoporous silica spheres. In this case, the carbon matrixes contain mesopores with a narrow pore size distribution and with diameters in the order of the wall thickness of the mesoporous silica used as hard template.

Keywords : nano-casting; porous carbon; non-porous silica; mesoporous silica; MCM-41; MCM-48; nanospheres.