The preparation of activated carbon discs from tar pitch and coal powder for adsorption of CO 2, CH 4 and N 2

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 μm, 150–250 μm, and 355–550 μm). 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 μm 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, N2, 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 μm and pitch pre-treated with 18 mL HNO3 per 100 g pitch were 3.08 mol/kg N2, 5.48 mol/kg CH4 and 8.88 mol/kg CO2 at about 3500 kPa