Construction of synergistic binding sites in a robust MOF for excellent C2H4 purification and C3H6 recovery performance

Abstract

C₂H₄ purification and C₃H₆ recovery by physisorbents face a huge dilemma in simultaneously achieving good separation performance, easy scalability, economic feasibility, and great stability for industrial applications. Herein, we propose a strategy of building multiple affinities in robust Ni(bdc)(dabco)_0.5 for highly effective one-step C₂H₄ purification from a C₃H₆/C₂H₄ mixture in the products of the MTO process and steam cracking of naphtha. Due to its nonpolar pores containing available O binding sites with suitable pore restriction and high BET surface area, Ni(bdc)(dabco)_0.5 shows not only one of the highest C₃H₆ uptake (80.6 cm³(STP) g⁻¹) at 0.1 bar and excellent C₃H₆ uptake (148.8 cm³(STP) g⁻¹) at 1.0 bar but also top-level C₃H₆/C₂H₄ selectivity (10.7) and separation potential (115.3 cm³(STP) g⁻¹) at 298 K and 1.0 bar. Meanwhile, its C₃H₆/C₂H₄ uptake ratio (10.9) exhibits a record value at 0.1 bar with a lower (26.7 kJ mol⁻¹), breaking the trade-off with C₃H₆/C₂H₄ separation and setting a new benchmark. Theoretical simulation and in situ FT-IR unveiled that the nonpolar pores with rich O binding sites supplied stronger multiple supramolecular affinities for C₃H₆ over C₂H₄. Breakthrough tests proved its total separation performance for C₃H₆/C₂H₄ with good recyclability, offering one of the highest dynamic C₃H₆ uptake and C₂H₄ productivity (101.2 and 57.3 cm³ (STP) g⁻¹, respectively). Additionally, the MOF is easy to synthesize on a gram-scale using cheap reagents. Ni(bdc)(dabco)_0.5 fulfills the benchmark combination of good separation performance, great stability, good renewability, and easy scalability, which endows it with great prospect for industrial C₂H₄ purification.