Metal–Organic Frameworks as Catalysts for Oxidation Reactions

Abstract

This Concept is aimed at describing the current state of the art in metal-organic frameworks (MOFs) as heterogeneous catalysts for liquid-phase oxidations, focusing on three important substrates, namely, alkenes, alkanes and alcohols. Emphases are on the nature of active sites that have been incorporated within MOFs and on future targets to be set in this area. Thus, selective alkene epoxidation with peroxides or oxygen catalyzed by constitutional metal nodes of MOFs as active sites are still to be developed. Moreover, no noble metal-free MOF has been reported to date that can act as a general catalyst for the aerobic oxidation of primary and secondary aliphatic alcohols. In contrast, in the case of alkanes, a target should be to tune the polarity of MOF internal pores to control the outcome of the autooxidation process, resulting in the selective formation of alcohol/ketone mixtures at high conversion.

Metal–Organic Frameworks Encapsulating Active Nanoparticles as Emerging Composites for Catalysis: Recent Progress and Perspectives

“…As for metal nodes, they are commonly associated with transition metals that likely introduce Lewis acidity, since several coordination positions of the metal centers are often occupied by solvent molecules that can be removed by heating or evacuation while keeping their frameworks. Furthermore, these metal nodes can undergo redox catalysis or promote coupling reactions . It should be pointed out that the metal sites are highly ordered in MOFs and exhibit the identical catalytic activity, which cannot be achieved by conventional heterogeneous catalysts.…”

Catalytic Transfer Hydrogenation of Biomass‐Derived Carbonyls over Hafnium‐Based Metal–Organic Frameworks

“…MOFs have been explored for a broad range of catalytic transformations. Reported examples are condensation, ring opening, cycloaddition, N ‐alkylation, isomerization, hydrogenation, oxidation, and carbene reactions. MOF‐based materials are suitable catalysts for the production of certain fine chemicals .…”

Catalytic Aerobic Oxidation of C(sp3)−H Bonds

“…[73] Alarge advantage of MOFs is their easy preparation and the ease of modification of the organic fragment, allowing fine-tuning of the catalyst structure and its activity.F urthermore they are excellent supports for metal nanoparticles due to their high surface area and porosity.L ie ta l. illustrated that Au-Pd bimetallic alloy nanoparticles deposited on MIL-101, comprising Cr salts and TA as the organic linker, acted as ahighly active and selective catalyst in the oxidation of cyclohexane (cyHex) (Scheme 13), ag ood model compound for alkane oxidation. [73] Alarge advantage of MOFs is their easy preparation and the ease of modification of the organic fragment, allowing fine-tuning of the catalyst structure and its activity.F urthermore they are excellent supports for metal nanoparticles due to their high surface area and porosity.L ie ta l. illustrated that Au-Pd bimetallic alloy nanoparticles deposited on MIL-101, comprising Cr salts and TA as the organic linker, acted as ahighly active and selective catalyst in the oxidation of cyclohexane (cyHex) (Scheme 13), ag ood model compound for alkane oxidation.…”