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 degrees C, and its ethane/ethylene adsorption selectivity became higher compared to A-ACs, reaching as high as 3.0 approximate to 20.6 below 100 kPa, significantly superior to the reported ethane-selective adsorbents. Simulation results revealed the mechanism of enhanced selectivity toward C2H6/C2H4, and suggested that the surface oxygen functionalities of the composites play predominant role in enhancing ethane/ethylene adsorption selectivity. Fixed-bed experiments showed that C2H6/C2H4 mixtures can be well separated at room temperature, suggesting great potential for industrial C2H6/C2H4 separation. (c) 2018 American Institute of Chemical Engineers AIChE J, 64: 3390-3399, 2018