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

- A series of asphalt-based activated carbons (A-ACs) are successfully synthesized.
- A-ACs exhibit ultra-high BET area of 3111 m2/g and pore volume of 1.92 cm3/g.
- A-ACs are ethane-selective adsorbents with super high ethane uptake of 7.2 mmol/g at 25 °C and 100 kPa.
- Ethane/ethylene adsorption selectivity of A-ACs is up to 16.3 for the cracked gas mixture.

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 °C and the KOH/asphalt ratio = 4 exhibited ultra-high BET area of 3111 m2/g and its pore volume reached 1.92 cm3/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 °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 π-complexation adsorbents. Therefore, these excellent adsorption properties would make A-ACs as a type of promising adsorbents for adsorption separation of C2H6/C2H4.

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