Construction of negative electrostatic sugared gourd pore within nickel-based metal-organic framework for one-step purification acetylene from ethylene and carbon dioxide mixture

The development of highly efficient adsorbents for purifying acetylene from multi-component mixtures is crucial in the chemical industry, yet the tradeoff between renewability and selectivity severely constrains practical industrial applications. This study introduces sugar gourd pore framework (SGPF-1), an innovative ultramicroporous framework synthesized using 1,2-di(4-pyridyl)ethylene (BPE), 4,4 ',4 ''-nitrilotribenzoic acid (NTA), and hexanitronickel under solvothermal conditions. The X-ray diffraction analysis has been used to prove the detailed structure and phase purity of SGPF-1. The structure of SGPF-1 was tailored for selectively adsorbing and separating the target compound, C2H2. The negative electrostatic effect, inspired by the natural sugared gourd structure, enhances the selectivity and adsorption capacity for C2H2, while minimizing the interaction with impurities like C2H4 and CO2. Experimental data show that SGPF-1 exhibits significantly higher adsorption of C2H2 compared to C2H4 and CO2 at 298 K and 100 kPa, demonstrating exceptional selectivity towards 50/50 C2H2/CO2 and 1/99 C2H2/C2H4 to be 7.33 and 15.46. Breakthrough experiments confirm its effectiveness in separating C2H2 from C2H4/CO2 mixtures, with C2H4 saturation reached within 5 to 15 min, while C2H2 retention time at 298 K was as long as 26 min. Theoretical calculations have revealed that SGPF-1 exhibits electrostatic compatibility with C2H2 while repelling C2H4 and CO2 through an electrostatic exclusion mechanism. This highlights the importance of rational pore engineering in optimizing the electrostatic properties of adsorbents for high-efficiency multi-component separations. The research aims to advance gas separation technologies and improve the purity of acetylene, a valuable industrial raw material.