Nanotubes are made exclusively of covalently bonded carbon atoms and could therefore be, in theory, the most resistant fibers obtainable with a Young modulus of the order of the tera-Pascal [32] and a resistance to traction of 250GPa [33] which would be one hundred times higher than the one displayed by steel while weighting six time less. In addition to these amazing resistance properties, it has been shown that CNT are flexible and can be bent several times at 90◦ without undergoing structural changes. Obviously, these values are theoretical and the presence of defects will reduce them, but their resistance will still be very high. The structure is not easily changed with the effects of pressure, and it has been demonstrated [34] that CNT are only undergoing permanent structure changing at very high pressures (over 1.5GPa) and that below that value the deformations are totally elastic. We have also conducted some experiments to evaluate the behavior of MWNT under the effect of pressure and temperature (5.5GPa, 800◦C) and our results show that, under these conditions, some structural modifications occur [35]. Interesting mechanical properties have also been reported for GNF and GNF granules [13]. Thus, we believe that such a support will display as good or even better properties than an activated carbon. Another important feature that has to be taken into consideration is the thermal stability under reaction conditions. The most common and simple way to study the resistance of the carbonaceous material towards