Supported Metal Pair-Site Catalysts

Guan, Erjia; Ciston, Jim; Bare, Simon R.; Runnebaum, Ron C.; Katz, Alexander; Kulkarni, Ambarish; Kronawitter, Coleman X.; Gates, Bruce C.

doi:10.1021/acscatal.0c02000

Cited by 77 publications

(78 citation statements)

References 134 publications

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“…For the foreseeable future, carbon-based fuels, such as natural gas, petroleum, and biomass, will continue to be a significant part of our energy infrastructure, and interfacially engineered heterogeneous catalytic materials relying on transition metal (TM) species will continue to play a critical role in meeting our daily energy needs. [1][2][3][4] It has been demonstrated that once supported or confined, TMs, their oxide, carbide and nitrides particles exhibit promising performance with high activity and selectivity in selective conversion of methane, [5][6][7][8] low-temperature CO conversion, 9,10 selective hydrogenation/dehydrogenation, [11][12][13][14] bio-oil conversion and upgrading, [15][16][17][18] and water-gas shift reaction 19,20 . Existing literature on heterogeneous catalytic materials primarily emphasize their outstanding performance and complexity in kinetics and reaction mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics of Molybdenum Trioxide (MoO3) Encapsulated in Zeolite Y

Zhang

Goncharov

et al. 2021

Preprint

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Zeolites with encapsulated transition metal species are extensively applied in the chemical industry as heterogenous catalysts for favorable kinetic pathways. To elucidate the energetic insights into formation of subnano-sized molybdenum trioxide (MoO3) encapsulated/confined in zeolite Y (FAU) from constituent oxides, we performed a systematic experimental thermodynamic study using high temperature oxide melt solution calorimetry as the major tool. Specifically, the formation enthalpy of each MoO3/FAU is less endothermic than corresponding zeolite Y, suggesting enhanced thermodynamic stability. As Si/Al ratio increases, the enthalpies of formation of MoO3/FAU with identical MoO3 loading tends to be less endothermic, ranging from 61.1 ± 1.8 (Si/Al = 2.9) to 32.8 ± 1.4 kJ/mol TO2 (Si/Al = 45.6). Coupled with spectroscopic, structural and morphological characterizations, and catalytic performance tests, we revealed intricate energetics of MoO3 – zeolite Y guest – host interactions and catalytic performance governed by the phase evolutions of encapsulated MoO3.

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Section: Introductionmentioning

confidence: 99%

Thermodynamics of Molybdenum Trioxide (MoO3) Encapsulated in Zeolite Y

Zhang

Goncharov

et al. 2021

Preprint

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“…Further work has been done to observe the formation of dimers. [ 60 ] Dimers which may have bond lengths not typically found in nanoparticles might be detected by EXAFS but this can be obscured through scattering paths with destructive interference or that have a weak signal due to long bond lengths. In addition, if the atoms are not directly bound but in close proximity due to the joint binding site or a bridging atom, it can be challenging to use EXAFS to detect the dimer.…”

Section: S/tem Imaging and Eds Analysis Of Sacsmentioning

confidence: 99%

Directly Probing the Local Coordination, Charge State, and Stability of Single Atom Catalysts by Advanced Electron Microscopy: A Review

Tieu

Yan

et al. 2021

Small

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of a heterogeneous catalyst. Any atom not at the catalyst surface is not directly used to drive chemical conversions, which is a critical consideration for the use of precious metal catalysts. To that end, the use of smaller particles with high surface/ volume ratios has been the preferred choice to maximize metal utilization. Recent advancements in the synthesis of nanomaterials with targeted shapes and sizes have resulted in the production of catalysts with designed catalytic properties. Single atom catalysts (SACs) have furthered the field of catalysis due to the potential for carefully controlled active site properties and distinct capabilities compared to bulk and nanoparticle catalysts. The reduction in size of the metal modifies the behavior through several mechanisms including: quantum size effect, [1][2][3][4] strong metal-support interactions (SMSI), [5][6][7] surface effects, [8][9][10][11] and varied oxidation states. [12] As a result of these influences, the coordination environment of single atoms on supports control their reactivity.Visualizing SACs is important to understand the formation, coordination environment, and stability of the catalyst. Oftentimes, bulk and nanoparticle catalysts release atoms during a catalytic process, which may contribute to the measured catalytic activity and changes in activity as a function of time. Recent work visualizing the release of Au single atoms, from nanoporous Au surfaces during methane pyrolysis, demonstrates the importance of visualizing catalysts at the atomic scaleThe drive for atom efficient catalysts with carefully controlled properties has motivated the development of single atom catalysts (SACs), aided by a variety of synthetic methods, characterization techniques, and computational modeling. The distinct capabilities of SACs for oxidation, hydrogenation, and electrocatalytic reactions have led to the optimization of activity and selectivity through composition variation. However, characterization methods such as infrared and X-ray spectroscopy are incapable of direct observations at atomic scale. Advances in transmission electron microscopy (TEM) including aberration correction, monochromators, environmental TEM, and microelectro-mechanical system based in situ holders have improved catalysis study, allowing researchers to peer into regimes previously unavailable, observing critical structural and chemical information at atomic scale. This review presents recent development and applications of TEM techniques to garner information about the location, bonding characteristics, homogeneity, and stability of SACs. Aberration corrected TEM imaging routinely achieves sub-Ångstrom resolution to reveal the atomic structure of materials. TEM spectroscopy provides complementary information about local composition, chemical bonding, electronic properties, and atomic/molecular vibration with superior spatial resolution. In situ/operando TEM directly observe the evolution of SACs under reaction conditions. This review concludes with remarks on the challenges an...

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“…And the formation of unsaturated sites offers opportunities to lower the reaction energy barrier by changing ligand environments around metal center. [ 120 ] Finally, apart from the interaction between metal atoms and supports, there is also a synergistic effect between metal atoms. The synergistic effect between metal atoms in DACs/SCCs can change the adsorption mode of the reactants and optimize the reaction pathway, thereby it can significantly improve the catalytic activity and selectivity.…”

Section: Bridging Remarks Between Sacs and Dacs/sccsmentioning

confidence: 99%

From double‐atom catalysts to single‐cluster catalysts: A new frontier in heterogeneous catalysis

Liu

Cao

et al. 2020

Nano Select

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In recent years, atomically dispersed metal catalysts with well‐defined structures have attracted great interest in heterogeneous catalysis due to their high atomic utilization efficiency, activity, stability, and selectivity. The rapid development of single‐atom catalysts (SACs) has simultaneously stimulated the emergence of diatomic catalysts (DACs) and single cluster catalysts (SCCs). Compared with SACs, DACs, and SCCs possess higher metal loading and more structurally flexible active sites, which provide great potential for achieving higher catalytic performance. DACs and SCCs have become a new field of heterogeneous catalysis. In this review, we first focus on the latest developments of DACs/SCCs, including synthesis methods and characterization approaches including experimental and theoretical tools. In addition, the relationship between structure and catalytic performance of DACs/SCCs are well discussed, including the effect of supports, synergistic metal atoms, and coordination environment. At last, the similarities and differences between SACs and DACs/SCCs are systematically summarized and analyzed.

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Supported Metal Pair-Site Catalysts

Cited by 77 publications

References 134 publications

Thermodynamics of Molybdenum Trioxide (MoO3) Encapsulated in Zeolite Y

Thermodynamics of Molybdenum Trioxide (MoO3) Encapsulated in Zeolite Y

Directly Probing the Local Coordination, Charge State, and Stability of Single Atom Catalysts by Advanced Electron Microscopy: A Review

From double‐atom catalysts to single‐cluster catalysts: A new frontier in heterogeneous catalysis

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