Effects of Mesopore Internal Surfaces on the Structure of Immobilized Pd-Bisphosphine Complexes Analyzed by Variable-Temperature XAFS and Their Catalytic Performances

Motokura, Ken; Fukuda, Takuma; Uemura, Yohei; Matsumura, Daiju; Ikeda, Marika; Nambo, Masayuki; Chun, Wang‐Jae

doi:10.3390/catal8030106

Cited by 4 publications

(3 citation statements)

References 15 publications

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“…In other words, the surface functionalities are located in close proximity and can interact with substrates together and activate them cooperatively. Similar DW value changing was also observed due to different morphologies of the silica support …”

Section: Concerted Effect On Surface For Enhanced Catalysissupporting

confidence: 76%

“…Similar DW value changing was also observed due to different morphologies of the silica support. 132 Cooperation between the immobilized Pd complex and support silica surface is another interesting effect that increases the Pd catalysis. In the field of supported organocatalysis, it is well-known that surface silanol groups can assist in catalytic reactions.…”

Section: Isolated Metal Complex For Enhanced Catalysismentioning

confidence: 99%

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Enhanced Catalysis Based on the Surface Environment of the Silica-Supported Metal Complex

et al. 2021

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Silica-supported metal complex catalysts have been developed and used for organic transformations. The surface environment around the supported metal complex enhances the catalysis based on a unique surface effect. The design of the linker ligand structure induces the formation of a highly reactive, coordinatively unsaturated metal complex on the silica surface because of the isolated environment. In contrast to the site-isolation effect, the accumulated metal complexes and cocatalysts on the same surface facilitate the acceleration of the catalytic reaction by concerted catalysis. The immobilization of multiactive sites also promotes the tandem catalysis and development of complex products from simple molecules through successive reactions. Surface silanol species originating from the silica support also participate in the catalysis. The control of the immobilization density/location of metal complex/coimmobilized functionality/surface silanol is a key factor for the achievement of site-isolation/concerted catalysis. The direct interaction between the metal complex and coimmobilized functionality facilitates the formation of unique reactive species. The confinement effect of the pore structure of the support enhances the accumulation of active species in mesopores, which boosts the reaction rate, and slightly changes the ligand conformation, which increases the enantioselectivity. The direct support electronic effect is also one of the key factors affecting the surface organometallic chemistry (SOMC) and photooxidation of linker metal complexes. These acceleration effects were detected in both supported homogeneous catalysis and SOMC. Not only the local structure of the metal complex and its ligand but also the surface environment play the most important roles in enhancing the catalysis. In this Review, representative examples of silica-supported metal complexes whose catalysis is significantly enhanced by their surface long-range environment are summarized. The contributions of recent developments of spectroscopic techniques, including DNP-enhanced solid-state NMR and XAFS, which support the evaluation of such long-range interactions, are also discussed. The surface design of the silica-supported metal complex facilitates highly active, selective, and durable catalysis.

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Section: Concerted Effect On Surface For Enhanced Catalysissupporting

confidence: 76%

Section: Isolated Metal Complex For Enhanced Catalysismentioning

confidence: 99%

Enhanced Catalysis Based on the Surface Environment of the Silica-Supported Metal Complex

et al. 2021

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“…With progressively hydrothermal aging, the XANES profile was closer to that of metallic Pd reference. The dramatical increase of the peak at ~2.5 Å (metal Pd-Pd) and decrease of the peak at ~1.5 Å (Pd-O) in EXAFS profiles also indicated the transformation from PdO into metallic Pd species during hydrothermal aging for Pd/Beta-Si [44][45][46].…”

Section: The Analysis Of Pd Species In Pd/beta Zeolitesmentioning

confidence: 90%

Effects of Si/Al Ratio on Passive NOx Adsorption Performance over Pd/Beta Zeolites

et al. 2023

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In the current article, the effect of Si/Al ratio on the NOx adsorption and storage capacity over Pd/Beta with 1 wt% Pd loading was investigated. The XRD, 27Al NMR and 29Si NMR measurements were used to determine the structure of Pd/Beta zeolites. XAFS, XPS, CO-DRIFT, TEM and H2-TPR were used to identify the Pd species. The results showed that the NOx adsorption and storage capacity on Pd/Beta zeolites gradually decreased with the increase of Si/Al ratio. Pd/Beta-Si (Si-rich, Si/Al~260) rarely has NOx adsorption and storage capacity, while Pd/Beta-Al (Al-rich, Si/Al~6) and Pd/Beta-C (Common, Si/Al~25) exhibit excellent NOx adsorption and storage capacity and suitable desorption temperature. Pd/Beta-C has slightly lower desorption temperature compared to Pd/Beta-Al. The NOx adsorption and storage capacity increased for Pd/Beta-Al and Pd/Beta-C by hydrothermal aging treatment, while the NOx adsorption and storage capacity on Pd/Beta-Si had no change.

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Unexpected Formation of Triphenylborane from Phenylboronic Acid and Its Use as an Intermediate in Palladium‐Catalyzed Cross Coupling Reaction

2019

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Triphenylborane was unexpectedly formed from phenylboronic acid in the presence of an inorganic base and a polar solvent. When K2CO3 was used as the base and DMF was used as the solvent, 0.22 mmol of triphenylborane was obtained from 1.5 mmol of phenylboronic acid after 1 h at 130 °C. The in‐situ formed triphenylborane reacted with chorobenzene over a supported Pd catalyst to afford biphenyl as the cross coupling product.

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Effects of Mesopore Internal Surfaces on the Structure of Immobilized Pd-Bisphosphine Complexes Analyzed by Variable-Temperature XAFS and Their Catalytic Performances

Cited by 4 publications

References 15 publications

Enhanced Catalysis Based on the Surface Environment of the Silica-Supported Metal Complex

Enhanced Catalysis Based on the Surface Environment of the Silica-Supported Metal Complex

Effects of Si/Al Ratio on Passive NOx Adsorption Performance over Pd/Beta Zeolites

Unexpected Formation of Triphenylborane from Phenylboronic Acid and Its Use as an Intermediate in Palladium‐Catalyzed Cross Coupling Reaction

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