Asphalt-derived high surface area activated porous carbons for the effective adsorption separation of ethane and ethylene

Abstract We reported novel asphalt–based activated carbons (A-ACs) with high C 2 H 6 /C 2 H 4 adsorption capacity and selectivity. A series of A-ACs were prepared by a one-step preparation method and characterized. The adsorption performances of A-ACs for ethane/ethylene were examined. Results showed that the sample A-ACs prepared at 800 °C and the KOH/asphalt ratio = 4 exhibited ultra-high BET area of 3111 m 2 /g and its pore volume reached 1.92 cm 3 /g. Their surface O and N contents gradually decreased with activation temperature or KOH/asphalt ratio at which A-ACs were prepared. More interestingly, A-ACs showed significantly preferential adsorption of C 2 H 6 over C 2 H 4 . It could be ascribed to the stronger interaction of C 2 H 6 with the surfaces of A-ACs by hydrogen bonds compared to C 2 H 4 , which were revealed by Density functional theory calculation. Its C 2 H 6 adsorption capacity was up to 7.2 mmol/g at 100 kPa and 25 °C and its C 2 H 6 /C 2 H 4 adsorption selectivity for typical cracked gas mixture (15:1 ethylene/ethane) was in the range of 3.2–16.3 at the pressure below 100 kPa, higher than the most reported ethane-adsorbents. Additionally, the isosteric heat of ethane and ethylene adsorption on A-ACs were lower than those on π -complexation adsorbents. Therefore, these excellent adsorption properties would make A-ACs as a type of promising adsorbents for adsorption separation of C 2 H 6 /C 2 H 4 .