Effect of sonication and hydrogen peroxide oxidation of carbon nanotube modifiers on the microstructure of pitch-derived activated carbon foam discs

We used carbon nanotubes (CNTs) as modifying particles and potassium hydroxide as a porogen to prepare mesoporous pitch-derived activated carbon discs (ACD) with high surface areas. The parameters investigated in this study included the concentration of CNTs (1%, 2%, 3.5% and 5%), the dispersion of the CNTs in the pitch using a 750 W sonic probe, the oxidation of the CNTs with H2O2, and the aspect ratio of the CNTs. The highest surface area ACD was obtained with 2% oxidized CNTs dispersed in the pitch with the ultrasonic probe (ACD-2%-SO, SBET = 2089 m2 g−1). The ACDs prepared with the sonic probe and with 2 wt% or more of raw and oxidized CNTs exhibited larger mesopore volumes than those ACDs prepared with 1 wt% CNTs. A series of quench tests performed during the foaming process by withdrawal of the carbon from the tube furnace at 673 K, 773 K and 873 K revealed that mesopores in ACD develop at temperatures ranging from 773 K to 873 K, whereas micropores formed between 873 K and 1073 K. The adsorption capacities of N2 and CO2 on ACD-2%-SO were measured with a gravimetric apparatus at 298 K and 303 K at pressures up to 4000 kPa. The uptake of CO2 on ACD-2%-SO at a temperature of 298 K was 3.33 mol/kg at 100 kPa and 11.51 mol/kg at 3496 kPa.

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