New insights on the direct activation of isotropic petroleum pitch by alkaline hydroxides

The paper provides interesting evidences that a low softening point isotropic petroleum pitch can be used as a good carbon precursor for the preparation of activated carbons. The activation is carried out by KOH and/or NaOH and the resulting activated carbons present well developed porosity. Such hydroxide activations can be done directly on the pristine petroleum pitch (P) or on the pitch that has been submitted to an air stabilisation followed by a N2 heat treatment (TAN). In general, KOH activation produces better results than NaOH, both in terms of porosity and yield, the results obtained for the activation of TAN being impressive because of the good porosity developments and high yields reached. The different treatments carried out over the petroleum pitch precursor clearly show that they significantly influence the extent of microporosity development. This is due to different changes occurring in the porous structure of the precursor as a function of the treatment carried out. The efficiency of the activation process increases as the mesophase content of the precursor decreases, as well as the mesophase formation during the activation process is avoided.

Single-walled carbon nanotube buckypapers as electrocatalyst supports for methanol oxidation

This work studies the use of various single-walled carbon nanotube (SWCNT) buckypapers as catalyst supports for methanol electro-oxidation in acid media. Buckypapers were obtained by vacuum filtration from pristine and oxidized SWCNT suspensions in different liquid media. Pt–Ru catalysts supported on the buckypapers were prepared by multiple potentiostatic pulses using a diluted solution of Pt and Ru salts (2 mM H2PtCl6 + 2 mM RuCl3) in acid media. The resulting materials were characterized via SEM, TEM, EDX and ICP-OES analysis. Well dispersed rounded nanoparticles between 2 and 15 nm were successfully electrodeposited on the SWCNT buckypapers. The ruthenium content in the bimetallic deposits was between 32 and 48 at. %, while the specific surface areas of the catalysts were in the range of 72–113 m2 g−1. It was found that the solvent used to prepare the SWCNT buckypaper films has a strong influence on the catalyst dispersion, particle size and metal loading. Cyclic voltammetry and chronoamperometry experiments point out that the most active electrodes for methanol electro-oxidation were prepared with the buckypaper supports that were obtained from SWCNT dispersions in N-methyl-pyrrolidone.