Optimized pore environment for efficient high selective C2H2/C2H4 and C2H2/CO2 separation in a metal-organic framework.

• Extremely simple and fast for the preparation of Ni 2 (BTEC)(bipy) 3 and highly yield. • Exhibits particular two-step adsorption of C 2 H 2 with enhanced adsorption sites. • Ni 2 (BTEC)(bipy) 3 has good regeneration properties and high air stability. • Exhibits very high C 2 H 2 /CO 2 and C 2 H 2 /C 2 H 4 uptake ratio and separation selectivity. Ethylene and acetylene are both important starting materials for the production of polyethylene, vinyl chloride, but-2-yne-1,4-diol, etc. To remove trace acetylene effectively from ethylene and the separation of acetylene from carbon dioxide are particularly challenging in the petrochemical industry. Although catalytic hydrogenation or cryogenic distillation for the separation of such light hydrocarbons is a very mature operation in the current petrochemical industry, it still requires huge capital and energy consumptions. Herein, a metal-organic framework (MOF), [Ni 2 (BTEC)(bipy) 3 ] (H 4 BTEC = 1,2,4,5-benzene tetracarboxylic acid, bipy = 4,4′-bipyridine), has been developed for efficient adsorptive separation of C 2 H 2 from C 2 H 2 /C 2 H 4 or C 2 H 2 /CO 2 mixtures. Ni 2 (BTEC)(bipy) 3 exhibited extraordinary two-step adsorption for C 2 H 2 with the adsorption capacity of 76.8 cm3/g at 298 K and 1 bar, significantly discriminating from C 2 H 4 (7.9 cm3/g) and CO 2 (13.0 cm3/g) in the same condition. The huge adsorption difference of Ni 2 (BTEC)(bipy) 3 between C 2 H 2 and C 2 H 4 /CO 2 resulted in the record high uptake ratio for C 2 H 2 /C 2 H 4 (9.7), C 2 H 2 /CO 2 (5.9) and very high ideal adsorption solution selectivity (104, 33.5) in robust MOFs at 298 K and 1 atm. The excellent separation performance was verified by breakthrough experiments; this material could effectively separate C 2 H 2 /C 2 H 4 or C 2 H 2 /CO 2 mixtures directly to obtain high purity of C 2 H 4 (>99.999%) and CO 2 (>99.99%) in one separation cycle. Furthermore, this material could be easily scaled up to be synthesized at room temperature under mild conditions, indicating the great potential in actual industrial applications. [ABSTRACT FROM AUTHOR]