Ethane selective adsorbent Ni(bdc)(ted)0.5 with high uptake and its significance in adsorption separation of ethane and ethylene

We reported a novel ethane selective metal–organic framework material Ni(bdc)(ted)0.5 with a high uptake of C2H6 and a decent selectivity towards C2H6/C2H4 separation. This material was synthesized with double ligands (bdc and ted) by a hydrothermal method. Its C2H6 and C2H4 isotherms were subsequently measured. The BET surface area of the synthesized Ni(bdc)(ted)0.5 reached 1701 m2/g. Successful assembling of the two organic ligands into Ni(bdc)(ted)0.5 was indicated by FT-IR. TGA indicated that Ni(bdc)(ted)0.5 was stable in the temperature region below 673 K. Ni(bdc)(ted)0.5 exhibited decent adsorption capacities of C2H6 and C2H4 with a superior high C2H6 adsorption capacity of 6.93 mmol/g at 100 kPa. More importantly, it exhibited preferential adsorption of C2H6 over C2H4. Its C2H6/C2H4 adsorption selectivity was in the range of 2–7.8 at pressure below 100 kPa, higher than the reported adsorbents possessing the characteristic of preferential adsorption of C2H6 over C2H4. In addition, the isosteric heat of C2H6 and C2H4 adsorption on Ni(bdc)(ted)0.5 were much lower compared to those π-complexation sorbents adsorbing olefin preferentially by binding with the π bond of olefin. The high ethane adsorption capacity, high ethane/ethylene selectivity and low isosteric heat of adsorption of Ni(bdc)(ted)0.5 would make it a promising adsorbent for the effective separation of ethane/ethylene.