HIERARCHICAL POROUS CARBON AS SUPPORT FOR PTRU CATALYSTS

RUSBEL CONEO R.; BAENA MONCADA, A. M.; ACEVEDO D. F.; PLANES G. A.; BARBERO C. A.; SOLDERA F.; MÜCKLICH F.

Campinas

Congreso; 6th International Workshop on Hydrogen and Fuel Cells – WICaC 2012.; 2012

Brazilian Reference Center for Hydrogen Energy

Hierarchical porous carbon (HPC) are very interesting carbon-based porous materials (PC). The materials are hierarchical because they have a multimodal porous size distribution, with each pore size contributting to the desired properties. Such materials could be obtained by the combination of different templates[ , ]. After impregnation with a carbon source (precursor) and solidification of the composite material, a heat treatment (pyrolysis) at high temperature (above 800 ºC) in the absence of oxygen turns the precursor into carbon. Since precursor materiales are organic polymers, containing hydrogen and oxygen besides carbon, the pyrolysis involve mass loss and volume contraction. Soft templates like polymers and surfactants are spontaneously eliminated during the burning of the material, and no post treatments are necessary for the pore voiding. On the other hand, hard templates like silica and metal oxides survive to high temperatures, and must be removed after pyrolysis by chemical etching. In this process, the space initially occupied by the templates is transformed into the pores in the resulting carbon materials. The whole process result in a reverse copy of the template[ ]. The different behaviour of those templates have been assigned to the soft or hard nature of the template. However, we will show that a key factor is the fact that hard templates obstruct contraction while soft templates allow contraction.