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

We reported novel asphalt-based activated carbons (A-ACs) with high C2H6/C2H4 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 degrees 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 C2H6 over C2H4. It could be ascribed to the stronger interaction of C2H6 with the surfaces of A-ACs by hydrogen bonds compared to C2H4, which were revealed by Density functional theory calculation. Its C2H6 adsorption capacity was up to 7.2 mmol/g at 100 kPa and 25 degrees C and its C2H6/C2H4 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 n-complexation adsorbents. Therefore, these excellent adsorption properties would make A-ACs as a type of promising adsorbents for adsorption separation of C2H6/C2H4. (C) 2017 Elsevier Ltd. All rights reserved.