A Cadmium Metal-Organic Framework with Negative Electrostatic Potentials for Efficient Separation of C2H2/CO2 and C2H2/C2H4.

Abstract

Given the high similarity in physical and chemical properties, especially in terms of molecular size and boiling point, of acetylene (C₂H₂), carbon dioxide (CO₂), and ethylene (C₂H₄) molecules, traditional separation techniques encounter great challenges. Fortunately, metal organic framework (MOF) materials have demonstrated significant potential for efficient separation of these gases at the molecular level due to their finely tunable pore structure and surface functional properties. In this paper, we have successfully synthesized a cadmium-based MOF (FJI-W-708), which exhibits negative electrostatic potential pores and exceptional thermal stability. It is worth noting that FJI-W-708 exhibits high C₂H₂ capacity (61 cm³/g), as well as appropriate selectivity towards C₂H₂/CO₂ (3.39) and C₂H₂/C₂H₄ (3.47). The dynamic breakthrough experiments of C₂H₂/CO₂ (50/50) mixture and C₂H₂/C₂H₄ (1/99) mixture clearly demonstrated the actual separation performance. The breakthrough time for C₂H₂/CO₂ (50/50) was observed to be 23 min/g, while for a C₂H₂/C₂H₄ (1/99) mixture it could reach up 46 min/g, demonstrating excellent recyclability and achieving a benchmark productivity of C₂H₄ at 4.12 mmol/g.