The separation of ethane from ethylene is of prime importance in the purification of chemical feedstocks for industrial manufacturing. However, differentiating these compounds is notoriously difficult due to their similar physicochemical properties. High-performance porous adsorbents provide a solution. Conventional adsorbents trap ethylene in preference to ethane, but this incurs multiple steps in separation processes. Alternatively, high-purity ethylene can be obtained in a single step if the adsorbent preferentially adsorbs ethane over ethylene. We herein report a metal−organic framework, MUF-15 (MUF, Massey University Framework), constructed from inexpensive precursors that sequesters ethane from ethane/ethylene mixtures. The productivity of this material is exceptional: 1 kg of MOF produces 14 L of polymer-grade ethylene gas in a single adsorption step starting from an equimolar ethane/ethylene mixture. Computational simulations illustrate the underlying mechanism of guest adsorption. The separation performance was assessed by measuring multicomponent breakthrough curves, which illustrate that the separation performance is maintained over a wide range of feed compositions and operating pressures. MUF-15 is robust, maintains its performance in the presence of acetylene, and is easily regenerated by purging with inert gas or by placing under reduced pressure.

We present a general strategy for incorporating organocatalytic moieties into metal-organic frameworks (MOFs). The organocatalytic units are protected by a thermolabile protecting group during MOF synthesis and then unveiled by a simple postsynthetic heating step. The strategy is exemplified using a thermolabile tert-butoxycarbonyl (Boc) protecting group for a proline moiety, the removal of which endows the resulting cubic zinc(II) IRMOF with catalytic activity for asymmetric aldol reactions. The bulky Boc groups also prevent framework interpenetration, producing open MOFs that can admit relatively large substrates.

We report a new methodology for producing monometallic or bimetallic nanoparticles confined within hollow nitrogen-doped porous carbon capsules. The capsules are derived from metal-organic framework (MOF) crystals that are coated with a shell of a secondary material comprising either a metal-tannic acid coordination polymer or a resorcinol-formaldehyde polymer. Platinum nanoparticles are optionally sandwiched between the MOF core and the shell. Pyrolysis of the MOF-shell composites produces hollow capsules of porous nitrogen-doped carbon that bear either monometallic (Pt, Co, and Ni) or alloyed (PtCo and PtNi) metal nanoparticles. The Co and Ni components of the bimetallic nanoparticles are derived from the shell surrounding the MOF crystals. The hollow capsules prevent sintering and detachment of the nanoparticles, and their porous walls allow for efficient mass transport. Alloyed PtCo nanoparticles embedded in the capsule walls are highly active, selective, and recyclable catalysts for the hydrogenation of nitroarenes to anilines.

Efficient and sustainable methods for carbon dioxide capture are highly sought after. Mature technologies involve chemical reactions that absorb CO2, but they have many drawbacks. Energy-efficient alternatives may be realised by porous physisorbents with void spaces that are complementary in size and electrostatic potential to molecular CO2. Here, we present a robust, recyclable and inexpensive adsorbent termed MUF-16. This metal-organic framework captures CO2 with a high affinity in its one-dimensional channels, as determined by adsorption isotherms, X-ray crystallography and density-functional theory calculations. Its low affinity for other competing gases delivers high selectivity for the adsorption of CO2 over methane, acetylene, ethylene, ethane, propylene and propane. For equimolar mixtures of CO2/CH4 and CO2/C2H2, the selectivity is 6690 and 510, respectively. Breakthrough gas separations under dynamic conditions benefit from short time lags in the elution of the weakly-adsorbed component to deliver high-purity hydrocarbon products, including pure methane and acetylene.

Metal-organic frameworks (MOFs) are microporous materials with huge potential for chemical processes, including retention or separation of guest molecules. Structural collapse at high-pressure, and transitions to liquid states at high temperature, have recently been observed in this family. Here, we show that the effect of simultaneous high pressure and temperature application on ZIF-62 and ZIF-4 results in complex behaviour, with distinct high-and low-density amorphous phases occurring over different regions of the pressure-temperature phase diagram. In-situ powder X-ray diffraction, Raman spectroscopy and optical microscopy reveal that the stability of the liquid MOF-state expands significantly towards lower temperatures at intermediate, industrially achievable pressures. Furthermore, the MOF-glass formed by melt quenching the high temperature liquid is shown to demonstrate permanent, accessible porosity. Our results thus imply a novel route to the synthesis of functional MOF glasses at low temperatures, avoiding decomposition upon heating at ambient pressure.

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To date, only several microporous, and even fewer nanoporous, glasses have been produced, always via post synthesis acid treatment of phase separated dense materials, e.g. Vycor glass. In comparison, high internal surface areas are readily achieved in crystalline materials, such as metal-organic frameworks (MOFs). It has recently been discovered that a new family of melt quenched glasses can be produced from MOFs, though they have thus far have lacked the accessible and intrinsic porosity of their crystalline precursors. Here, we report the first glasses that are permanently, and reversibly porous toward incoming gases, without post synthetic treatment. We characterized the structure of these glasses using a range of experimental techniques, and demonstrate pores in the 4-8 angstrom range. The discovery of MOF-glasses with permanent accessible porosity reveals a new category of porous glass materials, that are potentially elevated beyond conventional inorganic and organic porous glasses, by their diversity and tunability.

To generate metal-organic frameworks (MOFs) that are complex and modular yet well ordered, we present a strategy employing a family of three topologically distinct linkers that codes for the assembly of a highly porous quaternary MOF. By introducing substituted analogues of the ligands, a set of eight isoreticular frameworks is delivered, with the MOF structure systematically varied while the topology is maintained. To combat randomness and disorder, the substitution patterns of the ligands are designed to be compatible with their crystallographic site symmetries. MOFs produced in this way feature "programmed pores"--multiple functional groups compartmentalized in a predetermined array within a periodic lattice--and are capable of complex functional behavior. In these examples unconventional CO2 sorption trends, including capacity enhancements close to 100%, emerge from synergistic effects. Future PP-MOFs may be capable of enzyme-like heterogeneous catalysis and ultraselective adsorption.