Preparation of Metal Clusters in Zeolites

Gallezot, P.

doi:10.1007/3-540-69750-0_4

Cited by 27 publications

(39 citation statements)

References 221 publications

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“…The specific distribution of Si(OH)Al groups in noble metal-containing zeolites Y is caused by the migration of a large content of metal atoms into the sodalite cages, already upon calcination of their metal complexes. 9 The comparison of the number of Si(OH)Al groups generated per noble metal species in the bifunctional zeolites Y under study (acOH/NM ratio in Figure 3) and the acid strength of these hydroxyl groups (Δδ 1H values in Table 2, column 5) hints at a relationship between these two parameters (Topic (iii)). Low acOH/NM ratios are caused by incompletely reduced metal species corresponding to a high content of cationic metal species.…”

Section: Resultsmentioning

confidence: 98%

Generation and Properties of Brønsted Acid Sites in Bifunctional Rh-, Ir-, Pd-, and Pt-Containing Zeolites Y Investigated by Solid-State NMR Spectroscopy

et al. 2015

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In the present work, the generation and properties of Brønsted acidic bridging OH groups (Si(OH)Al) in Rh-, Ir-, Pd-, and Ptcontaining zeolites Y were quantitatively investigated by multinuclear solidstate NMR spectroscopy. The number of Si(OH)Al groups formed per noble metal atom upon their reduction was found to be 0.3 to 1.3 instead of the theoretically expected values of 2 (Pd 2+ , Pt 2+ ) or 3 (Rh 3+ , Ir 3+ ). For zeolites Y with low noble metal loadings, a significantly lower acid strength of Si(OH)Al groups in comparison with those of H,Na−Y zeolites occurred. Interestingly, noble metal-containing zeolites Y with lower acid strength have a significant content of not completely reduced noble metal atoms with partially cationic character. The spatial distribution of Si(OH)Al groups in noble metal-containing zeolites Y was found to differ significantly from that in H,Na−Y zeolites. This effect is explained by the migration of a significant content of noble metal atoms into the sodalite cages of zeolites Y already upon calcination of their noble metal complexes. Therefore, a much higher content of Si(OH)Al groups generated by the reduction of noble metal species in zeolites Y are located in sodalite cages compared to those in H,Na−Y zeolites.

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Section: Resultsmentioning

confidence: 98%

Generation and Properties of Brønsted Acid Sites in Bifunctional Rh-, Ir-, Pd-, and Pt-Containing Zeolites Y Investigated by Solid-State NMR Spectroscopy

et al. 2015

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“…2/a. The acidic OH band near 3600 cm -1 indicates the formation of Broensted acidity during the oxidative pre-treatment by the decomposition of the Pt(NH 3 ) 4 2+ complex which is well-known in the literature [8]. During the reduction in H 2 metallic Pt is formed.…”

Section: Experimental Methodsmentioning

confidence: 97%

IR spectroscopic study of the hydrodechlorination of 2-chlorophenol over nobel metal containing zeolites

Hannus

Mészáros

Búza

et al. 2009

React Kinet Catal Lett

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Some of the chlorinated organic compounds are widely used commercially because of their advantageous chemical/physical properties or having toxicity for pestiferous living substances. Platinum and palladium supported on different carriers play very important role in catalytic hydrodechlorination of these compounds. We have prepared and applied Pt-and Pd-containing zeolite catalysts for hydrotreating of 2-chlorophenol using IR spectroscopic self-supporting wafer technique.

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“…This is followed by reduction with hydrogen to form metal clusters or nanoparticles,a sw ell as sometimes oxidation for formation of fragmented species (so called mononuclear species). [29] This oxidation way has been successfully used to obtain site-isolated mononuclear noble metal catalysts. [54,55] Note that the exact nature of the formed species is often difficult to define.F or example,e xtended Xray absorption fine structure (EXAFS) results indicate the existence of aPt-N,Pt-O,and Pt-Al coordination shell, which Figure 2.…”

Section: Host-guest Assemblymentioning

confidence: 99%

“…[21,22] Zeolites,a sp romising porous supports,s hare core features as follows:1 )high surface area and strong interaction for stable dispersion of nanometals;2 )high physicochemical host stability for the structural integrity of the catalysts;3)highly ordered structure for high catalytic selectivity;a nd 4) high feasibility to various metals for practical applications. [29][30][31] Note that the specific adsorption sites in zeolites allow for the generation of nanoclusters of noble metals, creating ap artition between the exterior surface and the interior pores. [7] Furthermore,t he supercages in zeolites allow for the stabilization of unstable metal clusters,a nd offer an adjusting structure and volume to change the electronic configuration of nanometals, [32] whereby noble metals show very high catalytic activity and turnover frequency (TOF).…”

Section: Introductionmentioning

confidence: 99%

Confinement Effects in Zeolite‐Confined Noble Metals

2019

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Confinement of noble nanometals in a zeolite matrix is a promising way to special types of catalysts that show significant advantages in size control, site adjustment, and nano‐architecture design. The beauty of zeolite‐confined noble metals lies in their unique confinement effects on a molecular scale, and thus enables spatially confined catalysis akin to enzyme catalysis. In this Minireview, the confined synthesis strategies of zeolite‐confined noble metals will be briefly discussed, showing the processes, advantages, features, and mechanisms. The confined catalysis carried on zeolite‐confined noble metals will be summarized, and great emphasis will be paid to the confinement effects involving size, encapsulation, recognition, and synergy. Great progress of atomic sites in the size effect, supercage stabilization in the encapsulation effect, site adsorption in the recognition effect, and cascade reaction in the synergy effect are highlighted. This Minireview is concluded with challenges and opportunities in terms of the synthesis of zeolite‐confined noble metals and their applications to design multifunctional catalysts with high catalytic activity, selectivity, and stability.

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Preparation of Metal Clusters in Zeolites

Cited by 27 publications

References 221 publications

Generation and Properties of Brønsted Acid Sites in Bifunctional Rh-, Ir-, Pd-, and Pt-Containing Zeolites Y Investigated by Solid-State NMR Spectroscopy

Generation and Properties of Brønsted Acid Sites in Bifunctional Rh-, Ir-, Pd-, and Pt-Containing Zeolites Y Investigated by Solid-State NMR Spectroscopy

IR spectroscopic study of the hydrodechlorination of 2-chlorophenol over nobel metal containing zeolites

Confinement Effects in Zeolite‐Confined Noble Metals

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