Metal–Organic Framework Supported Palladium Nanoparticles: Applications and Mechanisms

Abstract

Heterogeneous palladium (Pd)‐based catalysts are extensively applied to improve the catalytic performance and/or expand the reaction scope in many catalytic processes, involving the cross‐coupling, hydrogenation, reduction, and oxidation reactions. Among them, metal–organic framework (MOF)‐supported Pd nanoparticles (Pd NPs) are becoming the most popular one for their excellent catalytic performance and reusable property. To motivate the development of this technology, the applications of MOF‐supported Pd NPs (Pd NPs/MOFs) in heterogeneous catalysis are critically summarized herein, including the hydrogenation reduction of nitro‐ and polyunsaturated compounds, synthesis of carbon–carbon (CC) bonds compounds, chromium (Cr(VI)) reduction, dehalogenation, alcohol oxidation, CO2 conversion, and CO oxidation. The influences of base, solvents, electron character of substitutes, and type of halogen on the catalytic performance are comprehensively discussed. Finally, the application prospects of Pd NPs/MOFs and existing shortcomings in the catalytic field are proposed.

Supported Metal Nanoparticles Assisted Catalysis: A Broad Concept in Functionalization of Ubiquitous C−H Bonds

“…Metal‐organic framework (MOF) have attracted intense attraction in various catalytic applications like Heck‐, Suzuki‐, and Sonogashira‐type coupling reactions, oxidation of CO, hydrogenation reduction of organic compounds, etc [87] . MOFs are excellent support material for such reaction because they have a uniform structure, large surface area, high porosity for hosting metal NPs and presence of aromatic linkers promotes stabilization of metal NPs by electronic and π‐π interaction.…”

Recent progress in application of nanocatalysts for carbonylative Suzuki cross-coupling reactions

“… 41,42 In this new class of heterogeneous catalysts, metal–organic framework-supported Pd nanoparticles are becoming the most popular one for their excellent catalytic performance and reusable property. 43 In this part, attention focuses on use of MOF-supported Pd NPs as catalysts in Suzuki carbonylative reactions.…”

A Smart Route for Encapsulating Pd Nanoparticles into a ZIF-8 Hollow Microsphere and Their Superior Catalytic Properties

“…1,2 To this end, the hybridization of NM NPs with metal-organic frameworks (MOFs) has emerged as a rational route that has stimulated considerable research interest, because (1) the catalytic activity can be enhanced by the confinement effect of MOF cavity that builds up local concentrations of reactants, as well as the synergy of the MOF shell and incorporated NM NPs; (2) the catalytic selectivity can be achieved by the modulation of the diameter and surface properties (hydrophilic or hydrophobic) of pores in the shell of MOFs, that enables selective and fast diffusion of reaction reagents through the interior cavities, especially for reactions in liquid phase; (3) the stability can be improved due to the porous shell of MOFs, that can reduce undesirable aggregation and atomic leaching of NM NPs. [3][4][5][6][7][8][9] However, it is challenging to encapsulate well-dispersed NM NPs into MOFs, and the resultant structures tend to suffer from nonuniform morphologies with NM NP aggregates inside the MOFs or NM NPs exposed on the external surface of MOFs. 10 Up to now, there have been few reports on the confined incorporation of many NM NPs within one MOF hollow microsphere (NM@MOF hollow microsphere).…”

“…The development of noble metal nanoparticles (NM NPs) as catalyst has received increasing attention because of their unique catalytic functions in various chemical reactions, but the improvement of their catalytic performance (activity, stability, and selectivity) by a convenient and controllable method remains a great challenge. , To this end, the hybridization of NM NPs with metal–organic frameworks (MOFs) has emerged as a rational route that has stimulated considerable research interest, because (1) the catalytic activity can be enhanced by the confinement effect of the MOF cavity that builds up local concentrations of reactants, as well as the synergy of the MOF shell and incorporated NM NPs; (2) the catalytic selectivity can be achieved by the modulation of the diameter and surface properties (hydrophilic or hydrophobic) of pores in the shell of MOFs, which enables selective and fast diffusion of reaction reagents through the interior cavities, especially for reactions in liquid phase; (3) the stability can be improved because of the porous shell of MOFs, which can reduce undesirable aggregation and atomic leaching of NM NPs. − However, it is challenging to encapsulate well-dispersed NM NPs into MOFs, and the resultant structures tend to suffer from nonuniform morphologies with NM NP aggregates inside the MOFs or NM NPs exposed on the external surface of MOFs …”