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The development of hydrogen sensors is of paramount importance for timely leak detection and remains a crucial unmet need. Palladium-based materials, well known as hydrogen sensors, still suffer from poisoning and deactivation. Here, a hybrid hydrogen sensor consisting of a Pd nanocluster (NC) film, a metal-organic framework (MOF), and a polymer, are proposed. The polymer coating, as a protection layer, endows the sensor with excellent H 2 selectivity and CO-poisoning resistance. The MOF serves as an interface layer between the Pd NC film and the polymer layer, which alters the nature of the interaction with hydrogen and leads to significant sensing performance improvements, owing to the interfacial electronic coupling between Pd NCs and the MOF. The strategy overcomes the shortcomings of retarded response speed and degraded sensitivity induced by the polymer coating of a Pd NC film-polymer hybrid system. This is the first exhibition of a hydrogen-sensing enhancement mechanism achieved by engineering the electronic coupling between Pd and a MOF. The work establishes a deep understanding of the hydrogen-sensing enhancement mechanism at the nanoscale and provides a feasible strategy to engineer next-generation gas-sensing nanodevices with superior sensing figures of merit via hybrid material systems., (© 2022 Wiley-VCH GmbH.)

Separation of hydrocarbon mixtures into single components is a very important industrial process because all represent very important energy resources/raw chemicals in the petrochemical industry. The well-established industrial separation technology highly relies on the energy-intensive cryogenic distillation processes. The discovery of new materials capable of separating hydrocarbon mixtures by adsorbent-based separation technologies has the potential to provide more energy-efficient industrial processes with remarkable energy savings. Porous metal-organic frameworks (MOFs), also known as porous coordination polymers, represent a new class of porous materials that offer tremendous promise for hydrocarbon separations because of their easy tunability, designability, and functionality. A number of MOFs have been designed and synthesized to show excellent separation performance on various hydrocarbon separations. Here, we summarize and highlight some recent significant advances in the development of microporous MOFs for hydrocarbon separation applications.

One‐step separation of C2H4 from ternary C2 mixtures by physisorbents remains a challenge to combine excellent separation performance with high stability, low cost, and easy scalability for industrial applications. Herein, we report a strategy of constructing negative electrostatic pore environments in a stable, low‐cost, and easily scaled‐up aluminum MOF (MOF‐303) for efficient one‐step C2H2/C2H6/C2H4 separation. This material exhibits not only record high C2H2 and C2H6 uptakes, but also top‐tier C2H2/C2H4 and C2H6/C2H4 selectivities at ambient conditions. Theoretical calculations combined with in situ infrared spectroscopy indicate that multiple N/O sites on pore channels can build a negative electro‐environment to provide stronger interactions with C2H2 and C2H6 over C2H4. Breakthrough experiments confirm its exceptional separation performance for ternary mixtures, affording one of the highest C2H4 productivity of 1.35 mmol g−1. This material is highly stable and can be easily synthesized at kilogram‐scale from cheap raw materials using a water‐based green synthesis. The benchmark combination of excellent separation properties with high stability and low cost in scalable MOF‐303 has unlocked its great potential in this challenging industrial separation. [ABSTRACT FROM AUTHOR]

Developing porous materials to overcome the trade‐off between adsorption capacity and selectivity for C2H2/CO2 separation remains a challenge. Herein, we report a stable HKUST‐1‐like MOF (ZJU‐50a), featuring large cages decorated with high density of supramolecular binding sites to achieve both high C2H2 storage and selectivity. ZJU‐50a exhibits one of the highest C2H2 storage capacity (192 cm3 g−1) and concurrently high C2H2/CO2 selectivity (12) at 298 K and 1 bar. Single‐crystal X‐ray diffraction studies on gas‐loaded ZJU‐50a crystal unveil that the incorporated supramolecular binding sites can selectively take up C2H2 molecule but not CO2 to result in both high C2H2 storage and selectivity. Breakthrough experiments validated its separation performance for C2H2/CO2 mixtures, providing a high C2H2 recovery capacity of 84.2 L kg−1 with 99.5 % purity. This study suggests a novel strategy of engineering supramolecular binding sites into MOFs to overcome the trade‐off for this separation. [ABSTRACT FROM AUTHOR]

Porous materials for C2H2/CO2 separation mostly suffer from high regeneration energy, poor stability, or high cost that largely dampen their industrial implementation. A desired adsorbent should have an optimal balance between excellent separation performance, high stability, and low cost. We herein report a stable, low‐cost, and easily scaled‐up aluminum MOF (CAU‐10‐H) for highly efficient C2H2/CO2 separation. The suitable pore confinement in CAU‐10‐H can not only provide multipoint binding interactions with C2H2 but also enable the dense packing of C2H2 inside the pores. This material exhibits one of the highest C2H2 storage densities of 392 g L−1 and highly selective adsorption of C2H2 over CO2 at ambient conditions, achieved by a low C2H2 adsorption enthalpy (27 kJ mol−1). Breakthrough experiments confirm its exceptional separation performance for C2H2/CO2 mixtures, affording both large C2H2 uptake of 3.3 mmol g−1 and high separation factor of 3.4. CAU‐10‐H achieves the benchmark balance between separation performance, stability, and cost for C2H2/CO2 separation. [ABSTRACT FROM AUTHOR]

Separation of acetylene (C2H2) and carbon dioxide (CO2) is of prime importance in the petrochemical industry, but their similarities in molecular size and volatility make it particularly difficult. A desired adsorbent for highly efficient C2H2/CO2 separation should have high selectivity and C2H2 uptake simultaneously, and the introduction of functional groups into MOFs is an effective strategy to achieve this purpose. Herein, we report a titanium‐based MOF material (MIL‐125‐NH2), featuring the suitable pore sizes and amino‐functionalized pore surfaces to show the preferential adsorption of C2H2 over CO2 with both high C2H2 uptake and C2H2/CO2 selectivity. Theoretical simulation results indicate that the preferential C2H2 adsorption is mainly attributed to multiple hydrogen bonding interactions between C2H2 molecule and amino functional groups. [ABSTRACT FROM AUTHOR]

A novel expanded metal–organic framework (UTSA-111a) with functional pyrimidine sites exhibits simultaneously high gravimetric and volumetric methane storage working capacities of 309 cm3 (STP) g−1 and 183 cm3 (STP) cm−3 at 298 K and 5.8–65 bar. [ABSTRACT FROM AUTHOR]

Separation of propyne/propylene (C3H4/C3H6) is more difficult and challenging than that of acetylene/ethylene (C2H2/C2H4) because of their closer molecular sizes. A comprehensive screening of a series of metal–organic frameworks with broad types of structures, pore sizes, and functionalities was carried out. UTSA‐200 was identified as the best separating material for the removal of trace C3H4 from C3H4/C3H6 mixtures. Gas sorption isotherms reveal that UTSA‐200 exhibits by far the highest C3H4 adsorption capacity (95 cm3 cm−3 at 0.01 bar and 298 K) and record C3H4/C3H6 selectivity, which was mainly attributed to the suitable dynamic pore size to efficiently block the larger C3H6 molecule whilst the strong binding sites and pore flexibility capture smaller C3H4. This material thus provides record purification capacity for the removal of C3H4 from a 1:99 (or 0.1:99.9, v/v) C3H4/C3H6 mixture to produce 99.9999 % pure C3H6 with a productivity of 62.0 (or 142.8) mmol g−1. [ABSTRACT FROM AUTHOR]

A new lvt-type metal–organic framework UTSA-60a with suitable pore channels and open metal sites has been developed for highly selective separation of C2H2/C2H4 at room temperature. [ABSTRACT FROM AUTHOR]

Review: 439 refs. [ABSTRACT FROM AUTHOR]

• Unique pore structure enables the dense packing of Xe inside the pores. • Both high Xe sorption capacity and Xe/Kr selectivity are achieved. • The highest Xe storage density at ambient conditions. For adsorptive separation of xenon/krypton mixture, it still remains a daunting challenge to target both high Xe adsorption and selectivity in a single adsorbent because of their close size and inert nature. Herein, we report an ultra-microporous alkyl Cu-based MOF-11 with suitable pore architecture for benchmark Xe capture and separation. MOF-11 features small pore channels (4.4 Å) close to the kinetic diameter of Xe, in which a large number of alkyl cavities and oppositely adjacent open Cu-metal sites are densely arranged along the pore channels in staggered mode. Such unique pore system can not only introduce strong binding affinity with Xe, but also enable the dense packing of Xe inside the pores. This material shows the highest Xe storage density of 2826 g/L at ambient conditions, record-high Xe uptake (4.0 mmol g−1at 0.2 bar and 298 K) and one of the highest Xe/Kr selectivity (19.1). The Xe locations within MOF-11 were visually identified by single-crystal X-ray diffraction experiment, which unveils the dense packing mechanism of Xe within the pores accountable for the record Xe capture capacity. The breakthrough experiments confirm that MOF-11 exhibits the exceptional separation performance for 20/80Xe/Kr mixture with both record-high Xe uptake capacity (3.46 mmol g−1) and Kr productivity (350 cm3 g−1). [ABSTRACT FROM AUTHOR]