Oriented Decoration in Metal-Functionalized Ordered Mesoporous Silicas and Their Catalytic Applications in the Oxidation of Aromatic Compounds

Abstract

Ordered mesoporous silicas (OMSs) attract considerable attention due to their advanced structural properties. However, for the pristine silica materials, the inert property greatly inhibits their catalytic applications. Thus, to contribute to the versatile surface of OMSs, different metal active sites, including acidic/basic sites and redox sites, have been introduced into specific locations (mesoporous channels and framework) of OMSs and the metal-functionalized ordered mesoporous silicas (MOMSs) show great potential in the catalytic applications. In this review, we first present the categories of metal active sites. Then, the synthesized processes of MOMSs are thoroughly discussed, in which the metal active sites would be introduced with the assistance of organic groups into the specific locations of OMSs. In addition, the structural morphologies of OMSs are elaborated and the catalytic applications of MOMSs in the oxidation of aromatic compounds are illustrated in detail. Finally, the prospects for the future development in this field are proposed.

Catalytic Behavior of Metal Active Sites From Modified Mesoporous Silicas in Oxidation of Organic Compounds

“…The imobilization of active metals in the specific locations of ordered mesoporous silicas by direct synthesis routes with the help of organic groups of surfactants brought a new aspect of creating metal-functionalized OMSs [51]. Although the strong interactions between active metals and support were obtained, the controllable morphology and structure of OMSs synthesized by these direct synthesis routes have not been well developed.…”

Synthesis, Characterization and Catalytic application of Mn-MFI prepared by Different Methods

“…Zhou hypothesized that manganese (II and III) coexisted in the Mn-MCM-41 samples made using different techniques and that a significant portion of Mn species may be integrated to the MCM-41 framework made using the direct hydrothermal technique. The coexistence of manganese cations was examined using electron spin resonance (ESR) and X-ray absorption near edge structure (XANES) 21 . Mn-MCM-41 produced by the DHT technique under mildly alkaline circumstances, framework Mn 2+ was found 21 .…”

“…The coexistence of manganese cations was examined using electron spin resonance (ESR) and X-ray absorption near edge structure (XANES) 21 . Mn-MCM-41 produced by the DHT technique under mildly alkaline circumstances, framework Mn 2+ was found 21 . The authors hypothesized that, in addition to the existence of extra-framework Mn 2+ , thermal treatment in air might cause the convert (oxidation) of Mn 2+ to Mn 3+ in the framework structure.…”

“…The authors hypothesized that, in addition to the existence of extra-framework Mn 2+ , thermal treatment in air might cause the convert (oxidation) of Mn 2+ to Mn 3+ in the framework structure. Furthermore, It was predicted to result in extra-framework-framework interactions with manganese 21 .…”

Diphosphine ligand‐containing model complex of [Fe]‐H2ase active site as direct phenol hydroxylation catalyst in the aqueous phase

“…In comparison to homogeneous catalysts, heterogeneous catalysts have garnered increased attention due to their low solubility and good recoverability. [9][10][11] Various heterogeneous catalysts have been developed previously, including mixed-oxide CuO@CeO 2 , 2 iron-based catalysts, [12][13][14][15] titanium-silicon molecular sieve (TS-1), 16 copper-based catalysts including copper-modified molecular sieves (Cu/MCM-41), 17 copper-containing metal-organic frameworks, 18 ordered mesoporous silicas, 19 etc. Among these, TS-1, the most utilized and investigated, was discovered in the early 1980s by Enichem and exhibits a phenol conversion of 25%.…”