Dual‐Ligand‐Engineered Ultramicroporous Porphyrinic MOF for Efficient C ₂ H ₆ /C ₂ H ₄ and C ₂ H ₂ /CO ₂ Separations

ABSTRACT Ultramicroporous MOFs capable of simultaneously separating C ₂ H ₆ /C ₂ H ₄ and C ₂ H ₂ /CO ₂ mixtures remain rare due to the stringent requirements on pore confinement and adsorption‐site distribution. Here, we report a dual‐ligand engineered porphyrin‐based framework, Zn‐TCPP‐mtz, constructed from Zn ²⁺ nodes, tetrakis(4‐carboxyphenyl)porphyrin (TCPP), and 5‐methyl‐1H‐tetrazole (mtz). The incorporated mtz ligands bridge adjacent porphyrin layers and, together with interlayer hydrogen‐bonding interactions, result in a compact stacking arrangement featuring 1D ultramicropores (7.2 × 4.8 Å ² ) decorated with N/O functional sites and hydrophobic methyl groups. This tailored pore environment enables Zn‐TCPP‐mtz to adsorb 2.63 and 2.56 mmol g ⁻¹ of C ₂ H ₆ and C ₂ H ₄ , respectively, as well as 3.14 and 1.89 mmol g ⁻¹ of C ₂ H ₂ and CO ₂ at 298 K and 1 bar, achieving selectivities of 1.5 for C ₂ H ₆ /C ₂ H ₄ and 3.1 for C ₂ H ₂ /CO ₂ . Dynamic breakthrough experiments confirm one‐step production of high‐purity C ₂ H ₄ (>99.9%) and C ₂ H ₂ (>99.5%) with productivities of 3.0 and 16.3 L kg ⁻¹ , respectively. DFT calculations reveal that the ultramicroporous channels provide well‐defined interaction sites that stabilize C ₂ H ₆ over C ₂ H ₄ and C ₂ H ₂ over CO ₂ through multiple dispersion‐dominated contacts. This study demonstrates that the dual‐ligand strategy can be extended to construct porphyrin‐based frameworks with controlled pore architectures and stable adsorption environments, enabling the integration of multiple C ₂ gas separations within a single material platform.