Activated carbons derived from petroleum coke (petcoke) have the potential to (a) help reduce sulfur dioxide emissions through desulfurization, (b) help reduce carbon dioxide and (c) utilize a common waste product. Herein we present results for the selective adsorption of H2S and CO2 from a synthetic sour gas mixture using 7 activated carbons, four derived from petcoke and three obtained commercially. The petcoke activated with sodium hydroxide (P_Na) showed an H2S/CH4 selectivity up to SH₂S/CH₄ = 152 in temperature swing adsorption experiments. The H2S/CH4 selectivity was observed to be inversely proportional to the BET apparent surface area and directly proportional to the oxygen content of the activated carbons. H2S/CH4 and H2S/CO2 selectivity for P_Na was found to increase with increasing temperature. The P_Na activated carbon maintained a high H2S selectivity (SH₂S/CH₄ > 50 and SH₂S/CO₂ > 20) after regeneration at temperatures of T = 423 – 723 K. Pure component CH4, CO2, and H2S adsorption isotherms at T = 288.15 K, 298.15 K and 308.15 K were collected and used to estimate the multi-component adsorption. The results of these studies indicate that the petcoke activated carbons are viable materials for separating H2S and CO2 from sour natural gas streams or biogas.
