Thermodynamic‐kinetic synergistic separation of CH₄/N₂ on a robust aluminum‐based metal‐organic framework

Abstract

A robust aluminum-based metal-organic framework (Al-MOF) MIL-120Al with 1D rhombic ultra-microporous was reported. The nonpolar porous walls composed of para-benzene rings with a comparable pore size to the kinetic diameter of methane allow it to exhibit a novel thermodynamic-kinetic synergistic separation of CH 4 /N 2 mixtures. The CH 4 adsorption capacity was as high as 33.7 cm 3 /g (298 K, 1 bar), which is the highest uptake value among the Al-MOFs reported to date. The diffusion rates of CH 4 were faster than N 2 in this structure as confirmed by timedependent kinetic adsorption profiles. Breakthrough experiments confirm that this MOF can completely separate the CH 4 /N 2 mixture and the separation performance is not affected in the presence of H 2 O. Theoretical calculations reveal that pore centers with more energetically-favorable binding sites for CH 4 than N 2 . The results of pressure swing adsorption (PSA) simulations indicate that MIL-120Al is a potential candidate for selective capture coal-mine methane.

Porous Metal–Organic Frameworks for Light Hydrocarbon Separation

“…The separation of CH 4 /N 2 can be achieved more efficiently based on a thermodynamickinetic synergistic separation mechanism than on a single thermodynamic or kinetic separation mechanism. In 2022, Zhang et al [37] chose aluminum nitrate and 1,2,4,5benzenetetracarboxylic acid (BTEC) as the main raw materials for the synthesis of MIL-120Al. MIL-120Al has rhombic 1D nonpolar pores formed by benzene rings (parallel to the channel direction), and its pore size (0.54 × 0.47 nm) is comparable to the kinetic diameter of methane molecules, which is capable of the synergistic thermodynamic-kinetic separation of the CH 4 /N 2 mixture.…”

Tailoring a MOF‐based adsorbent with partitioned aliphatic pore spaces for efficient CH4 purification from natural gas

“…3,4 It is increasingly seen as a low-cost and cleaner alternative to coal and oil worldwide. [5][6][7][8][9] CH 4 is primarily produced from natural gas, shale gas, and biogas. 10 Of these, natural gas is notable for its high CH 4 content (70%-90%) and is recognized as the predominant source of CH 4 currently.…”

“…At present, CH 4 is widely used as a green fuel and raw material in both daily life and modern industry, especially with broad applications in new energy vehicles and power generation 3,4 . It is increasingly seen as a low‐cost and cleaner alternative to coal and oil worldwide 5–9 . CH 4 is primarily produced from natural gas, shale gas, and biogas 10 .…”