Jorge Gascon

An Amine-Functionalized MIL-53 Metal−Organic Framework with Large Separation Power for CO2 and CH4

Functionalizing the well-known MIL-53(Al) metal-organic framework with amino groups increases its selectivity in CO(2)/CH(4) separations by orders of magnitude while maintaining a very high capacity for CO(2) capture.

Metal–organic framework nanosheets in polymer composite materials for gas separation

Composites incorporating two-dimensional nanostructures within polymeric matrices hold potential as functional components for several technologies, including gas separation. Prospectively, employing metal-organic-frameworks (MOFs) as versatile nanofillers would notably broaden the scope of functionalities. However, synthesizing MOFs in the form of free standing nanosheets has proven challenging. We present a bottom-up synthesis strategy for dispersible copper 1,4-benzenedicarboxylate MOF lamellae of micrometer lateral dimensions and nanometer thickness. Incorporating MOF nanosheets into polymer matrices endows the resultant composites with outstanding CO2 separation performance from CO2/CH4 gas mixtures, together with an unusual and highly desired increment in the separation selectivity with pressure. As revealed by tomographic focused-ion-beam scanning-electron-microscopy, the unique separation behaviour stems from a superior occupation of the membrane cross-section by the MOF nanosheets as compared to isotropic crystals, which improves the efficiency of molecular discrimination and eliminates unselective permeation pathways. This approach opens the door to ultrathin MOF-polymer composites for various applications.

Ethane/Ethene Separation Turned on Its Head: Selective Ethane Adsorption on the Metal−Organic Framework ZIF-7 through a Gate-Opening Mechanism

Ethane is selectively adsorbed over ethylene in their mixtures on the zeolite imidazolate framework ZIF-7. In packed columns, this results in the direct production of pure ethylene. This gas-phase separation is attributed to a gate-opening effect in which specific threshold pressures control the uptake and release of individual molecules. These threshold pressures differ for the different molecules, leaving a window of selective uptake operation. This phenomenon makes ZIF-7 a perfect candidate for the separation of olefins from paraffins, since in contrast to most microporous materials, the paraffin is selectively adsorbed. Mixture adsorption, as studied by breakthrough experiments, demonstrates that gate-opening effects can be effectively used to separate molecules of very similar size.

Metal–organic frameworks as scaffolds for the encapsulation of active species: state of the art and future perspectives

The use of metal–organic frameworks (MOFs) for the encapsulation of different active entities is thoroughly reviewed. Either by following ship in a bottle or bottle around a ship approaches, active species can be encapsulated in the porous framework of different MOFs. Encapsulated species vary from polymers to organometallics and from polyoxometalates to metal nanoparticles and metal oxides. The main advantages and limitations of the use of MOFs together with the synthetic approaches followed are evaluated.

Understanding the anomalous alkane selectivity of ZIF-7 in the separation of light alkane/alkene mixtures.

C2 and C3 alkanes are selectively adsorbed from mixtures over the corresponding alkenes on the zeolite imidazolate framework ZIF-7 through a gate-opening mechanism. As a result, the direct production of the pure alkene upon adsorption and the pure alkane upon desorption in packed columns is possible. Herein, a detailed investigation of the step-wise adsorption and separation of alkanes and alkenes is presented, together with a rigorous performance assessment. A molecular picture of the gate-opening mechanism underlying the unprecedented selectivity towards alkane adsorption is proposed based on DFT calculations and a thermodynamic analysis of the adsorption-desorption isotherms.

Metal–organic frameworks as heterogeneous photocatalysts: advantages and challenges

The use of metal organic frameworks (MOFs) as heterogeneous photocatalysts is critically reviewed. First we revisit the general assumption of MOFs behaving truly as semiconductors, demonstrating that such semiconducting behaviour only occurs in a very limited subset of materials. Further, the main approaches for efficient light harvesting and active site engineering in MOF-based photocatalysts are discussed. Finally, the main advantages of MOFs as photocatalysts and the challenges that need to be addressed in order to improve catalytic performance are evaluated.

Isoreticular MOFs as Efficient Photocatalysts with Tunable Band Gap: An Operando FTIR Study of the Photoinduced Oxidation of Propylene

Photo frame(work): The first spectroscopic evidence of metal-organic frameworks (MOFs) acting as photocatalysts has been obtained. Isoreticular MOFs act as efficient photocatalysts in the photooxidation of propylene. The band gap energy can be tuned by changing the organic linker. Among the MOFs tested, the 2,6-naphthalenedicarboxylic acid based IRMOF was the most active, showing a higher activity than ZnO.

Co@NH2-MIL-125(Ti): cobaloxime-derived metal–organic framework-based composite for light-driven H2 production

We present a synthetic strategy for the efficient encapsulation of a derivative of a well-defined cobaloxime proton reduction catalyst within a photoresponsive metal–organic framework (NH2-MIL-125(Ti)). The resulting hybrid system Co@MOF is demonstrated to be a robust heterogeneous composite material. Furthermore, Co@MOF is an efficient and fully recyclable noble metal-free catalyst system for light-driven hydrogen evolution from water under visible light illumination.

Kinetic Control of Metal–Organic Framework Crystallization Investigated by Time‐Resolved In Situ X‐Ray Scattering

Metal–organic frameworks (MOFs) are among the most sophisticated nanostructured solids: they often possess high surface areas and pore volumes, with the possibility of finetuning their chemical environment by either selecting the appropriate building blocks or by postsynthetic functionalization. For many frameworks, flexibility of the lattice allows them to undergo a significant transformation in solid state.[1] All these features make MOFs a special class of solids with the potential of transcending many common limitations in different technological disciplines, such as ferromagnetism,[2] semiconductivity, gas separation,[3] storage,[4] sensing,[5] catalysis,[ 6] drug delivery,[7] or proton conductivity.[8] However, the crystallization mechanism of these complex structures is far from understood. Notwithstanding the plethora of publications that present new MOFs,[9] and the effectiveness of the high-throughput approach,[10] serendipity still governs the synthesis of new structures.

Metal organic framework-mediated synthesis of highly active and stable Fischer-Tropsch catalysts

Depletion of crude oil resources and environmental concerns have driven a worldwide research on alternative processes for the production of commodity chemicals. Fischer-Tropsch synthesis is a process for flexible production of key chemicals from synthesis gas originating from non-petroleum-based sources. Although the use of iron-based catalysts would be preferred over the widely used cobalt, manufacturing methods that prevent their fast deactivation because of sintering, carbon deposition and phase changes have proven challenging. Here we present a strategy to produce highly dispersed iron carbides embedded in a matrix of porous carbon. Very high iron loadings (>40 wt %) are achieved while maintaining an optimal dispersion of the active iron carbide phase when a metal organic framework is used as catalyst precursor. The unique iron spatial confinement and the absence of large iron particles in the obtained solids minimize catalyst deactivation, resulting in high active and stable operation.