One-step purification of ethylene is an important research topic in the petrochemical field, as it directly influences the energy consumption and economic efficiency of olefin production processes. In recent years, multicomponent metal- organic frameworks (MOFs), owing to their structural tunability and functional diversity, have demonstrated significant potential in C₂ hydrocarbon gas separation and purification of products from methanol-to-olefins (MTO) processes. To address the limitations of conventional single-metal-center MOFs, which often suffer from structural simplicity and restricted functionality, this work proposes a controllable construction strategy for multicomponent MOFs based on the assembly of metal- ligand units. Specifically, 2,2′-biquinoline-4,4′-dicarboxylic acid (H₂BQDC) was employed as the organic ligand and coordinated with CuBr via an in situ reaction to form the metal-ligand unit Cu(BQDC)₂. Subsequently, solvothermal reactions with ZrOCl₂, Fe₃O(OAc)₆(H₂O)₃, and Bi(NO₃)₃•9H₂O successfully yielded three structurally well-defined multicomponent MOF materials: Zr-Cu-BQDC, Quat-Fe-Cu-BQDC, and Quat-Bi-Cu-BQDC. Comprehensive structural characterization and gas adsorption measurements reveal that the introduction of different metal centers leads to significant variations in pore size, coordination environment, and surface chemical properties, which in turn result in distinct adsorption and separation behaviors. Among them, Zr-Cu-BQDC and Quat-Fe-Cu-BQDC exhibit preferential adsorption toward C₂H₂ and C₂H₆, enabling one-step separation of high-purity C₂H₄ from ternary C₂H₂/C₂H₆/C₂H₄ mixtures. In contrast, Quat-Bi-Cu-BQDC shows stronger affinity for C₃H₆ and demonstrates effective separation performance for C₃H₆/C₂H₄ mixtures typically found in MTO products. The feasibility of achieving efficient one-step ethylene purification under ambient conditions was validated through single-component gas adsorption measurements, ideal adsorbed solution theory (IAST) predictions, and dynamic breakthrough experiments. This work not only develops an efficient synthesis strategy for multicomponent MOFs based on metal-ligand units and enriches the preparation pathways of multicomponent MOFs, but also provides new insights and theoreti- cal guidance for the rational design of olefin separation materials tailored for practical industrial applications, highlighting both significant academic value and promising industrial potential.

Key words: multicomponent metal-organic frameworks, C₂ gas separation, methanol-to-olefins (MTO) product separation, one-step purification, adsorptive separation