The preparation of activated carbon discs from tar pitch and coal powder for adsorption of CO2, CH4 and N2

We used a pitch foaming process to prepare high surface area activated carbon discs (ACD) with a relatively high mechanical strength (4.3 MPa) from mixtures of tar pitch and coal powders, with potassium hydroxide as a chemical activator. The two primary parameters investigated in this study were the amount of nitric acid used in the pitch pre-treatment and the size of the coal particles (0-53 mu m,150 250 mu m, and 355-550 mu m). The pre-treatment of the pitch was observed to be critical in the production of the carbon discs and in this study the preferred ratio of 15 M nitric acid to pitch in weight was 17/100. The coal size of 0-53 mu m produced the activated carbon discs with the highest gas adsorption capacity, which we attribute to the stabilization of the pitch foaming process. Equilibrium adsorption capacities of CO2, N-2, and CH4 on the carbons were measured by a gravimetric sorption method at pressures up to 3500 kPa. At 298 K the adsorption capacities of carbon foam disc prepared with coal particle size of 0-53 mu m and pitch pre-treated with 18 mL HNO3 per 100 g pitch were 3.08 mol/kg N-2, 5.48 mol/kg CH4 and 8.88 mol/kg CO2 at about 3500 kPa. (C) 2016 Elsevier Inc. All rights reserved.