A chlorine-rich Zn-based metal-organic framework for efficient separation of C3H6/C2H4 and C2H6/C2H4

Abstract

In the petrochemical industry, efficiently achieving one-step purification of ethylene (C₂H₄) from propylene (C₃H₆) or ethane (C₂H₆) is a highly sought-after yet challenging task. Herein, we present a chlorine-rich Zn-based metal-organic framework (DMOF-1-Cl₂) that retains the essential topology of the parent DMOF-1 through the incorporation of 2,5-dichloroterephthalate linkers. The chlorine atoms within the square pores of DMOF-1-Cl₂, due to their high electronegativity, serve as potential adsorption sites. Gas adsorptive experiments revealed its preferential adsorption of C₃H₆ and C₂H₆ over C₂H₄ at different temperatures. Ideal adsorption solution theory calculation revealed that the selectivity of DMOF-1-Cl₂ for C₃H₆/C₂H₄ and C₂H₆/C₂H₄ reaches 20.8 and 2.2 at 313 K, respectively, outperforming its counterpart (DMOF-1-Br₂) and most previously reported adsorbents. Theoretical calculations indicated that the gas molecules are primarily distributed around the chlorine atoms with multiple interactions. Furthermore, dynamic breakthrough experiments fully demonstrated the actual potential for achieving one-step purification of polymer-grade C₂H₄, in which DMOF-1-Cl₂ displayed high productivity of 206.1 and 31.6 L kg⁻¹ from C₃H₆/C₂H₄ (2/5, v/v) and C₂H₆/C₂H₄ (1/9, v/v), respectively. Despite the fact that the yield of C₂H₄ separation from C₂H₆/C₂H₄ mixtures is not extremely high, it still remains at a satisfactory level, demonstrating the practical value and potential of DMOF-1-Cl₂ for industrial applications.