Ethane‐selective carbon composites CPDA@A‐ACs with high uptake and its enhanced ethane/ethylene adsorption selectivity

Novel composites (CPDA@A‐ACs) of carbonized polydopamine (CPDA) and asphalt‐based activated carbons (A‐ACs) were successfully synthesized, and characterized for adsorption separation of ethane/ethylene. The resulting CPDA@A‐ACs exhibited high Brunauer–Emmett–Teller surface area of 1971 m 2 /g. The O and N contents on CPDA@A‐ACs are higher than those on A‐ACs due to the introduction of CPDA. Interestingly, CPDA@A‐ACs exhibited great preferential adsorption of ethane over ethylene. Its ethane capacity reached as high as 7.12 mmol/g at 100 kPa and 25°C, and its ethane/ethylene adsorption selectivity became higher compared to A‐ACs, reaching as high as 3.0∼20.6 below 100 kPa, significantly superior to the reported ethane‐selective adsorbents. Simulation results revealed the mechanism of enhanced selectivity toward C 2 H 6 /C 2 H 4 , and suggested that the surface oxygen functionalities of the composites play predominant role in enhancing ethane/ethylene adsorption selectivity. Fixed‐bed experiments showed that C 2 H 6 /C 2 H 4 mixtures can be well separated at room temperature, suggesting great potential for industrial C 2 H 6 /C 2 H 4 separation. © 2018 American Institute of Chemical Engineers AIChE J , 64: 3390–3399, 2018