Trace mono-atomically dispersed rhodium on zeolite-supported cobalt catalyst for the efficient methane oxidation

Hou, Yuhui; Nagamatsu, Shin‐ichi; Asakura, Kiyotaka; Fukuoka, Atsushi; Kobayashi, Hirokazu

doi:10.1038/s42004-018-0044-9

Cited by 26 publications

(23 citation statements)

References 31 publications

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“…[69] In addition to 5d transition metal based catalysts, XAS has been used to determine the structure of SACs containing 4d noble metals such as Ru, Rh, and Pd atomically dispersed onto zeolites and MOFs. [70][71][72] Sun et al [70] studied Rh-based SACs and used Rh K-edge EXAFS measurements to determine the structural information of single Rh atoms encapsulated within S-1 zeolites (Rh@S-1-H and Rh@S-1-C). As shown in Figure 7A, upon comparison with Rh 2 O 3 and Rh foil references, Rh@S-1-C showed two major peaks corresponding to RhO and RhRh shells.…”

Section: Structural Characterizationmentioning

confidence: 99%

Single‐Atom Catalysts Supported by Crystalline Porous Materials: Views from the Inside

et al. 2020

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Reducing the size of nanoparticle catalysts is one desirable method that can improve their catalytic activity. Single-atom catalysts (SACs) represent the smallest possible size a catalyst can achieve with maximum atomic efficiency. [6] Moreover, recent studies have shown that the use of single-atom catalytic sites, rather than ensembles of atoms, is crucial in many catalytic reactions. [7] Without proper protection, however, single-atom sites in these catalysts are not stable since they tend to aggregate and form larger particles. [8-10] To solve this problem, many different protecting supports have been developed such as polymers and porous organic cages. [11,12] Crystalline porous materials, such as zeolites and metal-organic frameworks (MOFs), have been widely used to stabilize small metal species in catalytic reactions due to the controllable size, shape, and dimensions of their pores and channels. [13-15] Therefore, they are highly desirable in supporting SACs. [13] Despite the promising aspects of zeolite and MOF-supported SACs, their characterization remains challenging due to the single-atomic nature of their bonding environments; atomic-level resolution is needed for the structural characterization of these catalysts. X-ray absorption spectroscopy (XAS) is a powerful tool in studying the structure and properties of atoms in their coordination environments with subatomic resolution, [16,17] and thus is considered particularly suitable for the study of SACs. [16,17] In this contribution, a comprehensive review of representative works on zeolite-and MOF-protected SACs will be presented from the XAS perspective. The subatomic resolution (0.01 Å level) of synchrotron-based XAS technique allows for views from "inside" the SACs regarding their structure, electronic properties, and catalytic activities. The processed data from extended X-ray absorption fine structure (EXAFS) will be shown as a powerful tool to probe the atomic structure of SACs in zeolites and MOFs. Through the standard fitting analysis of EXAFS, together with the assistance of advanced analysis tools, detailed information concerning the local structure of SACs can be obtained. Additionally, it will be demonstrated that the X-ray absorption near-edge structure (XANES) can provide insight into the unique electronic properties of SACs. Furthermore, in situ/operando XAS techniques, coupled with state-of-the-art Single-atom catalysts (SACs) have recently emerged as an exciting system in heterogeneous catalysis showing outstanding performance in many catalytic reactions. Single-atom catalytic sites alone are not stable and thus require stabilization from substrates. Crystalline porous materials such as zeolites and metal-organic frameworks (MOFs) are excellent substrates for SACs, offering high stability with the potential to further enhance their performance due to synergistic effects. This review features recent work on the structure, electronic, and catalytic properties of zeolite and MOF-protected SACs, offering atomic-scale views from the "insid...

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Section: Structural Characterizationmentioning

confidence: 99%

Single‐Atom Catalysts Supported by Crystalline Porous Materials: Views from the Inside

et al. 2020

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“…Recently, various catalysts with precious and/or nonprecious metals for selective oxidation of CH 4 to CO and H 2 productions have been proposed [12][13][14][15][16][17][18][19][20][21] . In previous work, Kobayashi et al have reported a high performance using Rh/zeolite catalyst 18 ; Rh subnano clusters are formed on the MOR-type zeolite and this Rh/ MOR catalyst gave 84% CH 4 conversion and 91% selectivity for CO with H 2 /CO ratio of 2.0 at 873 K 18 .…”

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confidence: 99%

Zeolite-supported ultra-small nickel as catalyst for selective oxidation of methane to syngas

et al. 2020

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The development of simple catalysts with high performance in the selective oxidation of methane to syngas at low temperature has attracted much attention. Here we report a nickel-based solid catalyst for the oxidation of methane, synthesised by a facile impregnation method. Highly dispersed ultra-small NiO particles of 1.6 nm in size are successfully formed on the MOR-type zeolite. The zeolite–supported nickel catalyst gives continuously 97–98% methane conversion, 91–92% of CO yield with a H2/CO ratio of 2.0, and high durability without serious carbon deposition onto the catalyst at 973 K. DFT calculations demonstrate the effect of NiO particle size on the C-H dissociation process of CH4. A decrease in the NiO particle size enhances the production of oxygen originating from the NiO nanoparticles, which contributes to the oxidation of methane under a reductive environment, effectively producing syngas.

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“…Kobayashi et al reported that mono-atomically dispersed Rh atoms on Co atoms played supportive roles that maintained an active Co 0 state for efficient methane oxidation. 15 (iv) Electronic interactions between isolated atoms and the surrounding atoms induce high activity. Sykes et al reported the selective hydrogenation of butadiene to butene over an isolated Ptatom-containing Pt−Cu alloy.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Alloy catalysts are well known to exhibit unique catalytic behavior that is different from that of their monometallic counterparts, as a result of the “ligand effect” and the “ensemble effect”; however, the reaction mechanisms of alloy catalysts have not been fully elucidated yet. − In particular, isolated atoms surrounded by the atoms of another element in the alloy, which are referred to as “single atom alloys (SAAs)”, have received significant attention. − Although incipient reports of single-crystal SAA substrates have appeared in the surface science field, − more practical nanoparticle catalysts have been reported in recent years. − The electronic interactions and geometric positional relationships between single element “guest” atoms and the surrounding atoms of the “host” element are expected to induce unique catalytic behavior for the following four reasons. (i) Isolated atoms are active sites.…”

Section: Introductionmentioning

confidence: 99%

“…(iii) Both isolated atoms and their surroundings play cooperative roles. Kobayashi et al reported that mono-atomically dispersed Rh atoms on Co atoms played supportive roles that maintained an active Co 0 state for efficient methane oxidation . (iv) Electronic interactions between isolated atoms and the surrounding atoms induce high activity.…”

Section: Introductionmentioning

confidence: 99%

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Isolated Platinum Atoms in Ni/γ-Al₂O₃ for Selective Hydrogenation of CO₂ toward CH₄

et al. 2019

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We introduce a catalyst composed of isolated Pt atoms surrounded by Ni atoms in a Ni−Pt alloy (iso-Pt), which was prepared on aluminum oxide (Al 2 O 3 ) obtained by a simple impregnation method with typical hydrogen reduction pretreatment. This catalyst exhibited a relatively high CH 4 -formation rate while maintaining excellent selectivity for CH 4 evolution, when compared to bulk Ni atoms (bulk-Ni), although bulk Pt atoms (bulk-Pt) produced CO rather than CH 4 . Kinetic studies revealed that one of the two roles of the iso-Pt species in the Ni−Pt alloy is to provide H 2 dissociation sites at low temperature, resulting in high CO 2 methanation activity. Fourier transform infrared spectroscopy clarified the second role of the iso-Pt species; tuning of the d-electronic state by alloying to surrounding Ni atoms leads to CO molecules that are strongly anchored to the iso-Pt atoms, which weakens the C−O bond of the CO species attached to the Pt atoms and improves the abilities of the surrounding Ni atoms to promote further methanation with hydrogen.

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Trace mono-atomically dispersed rhodium on zeolite-supported cobalt catalyst for the efficient methane oxidation

Cited by 26 publications

References 31 publications

Single‐Atom Catalysts Supported by Crystalline Porous Materials: Views from the Inside

Single‐Atom Catalysts Supported by Crystalline Porous Materials: Views from the Inside

Zeolite-supported ultra-small nickel as catalyst for selective oxidation of methane to syngas

Isolated Platinum Atoms in Ni/γ-Al₂O₃ for Selective Hydrogenation of CO₂ toward CH₄

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Trace mono-atomically dispersed rhodium on zeolite-supported cobalt catalyst for the efficient methane oxidation

Cited by 26 publications

References 31 publications

Single‐Atom Catalysts Supported by Crystalline Porous Materials: Views from the Inside

Single‐Atom Catalysts Supported by Crystalline Porous Materials: Views from the Inside

Zeolite-supported ultra-small nickel as catalyst for selective oxidation of methane to syngas

Isolated Platinum Atoms in Ni/γ-Al2O3 for Selective Hydrogenation of CO2 toward CH4

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Isolated Platinum Atoms in Ni/γ-Al₂O₃ for Selective Hydrogenation of CO₂ toward CH₄