Quasi free K cations confined in hollandite-type tunnels for catalytic solid (catalyst)-solid (reactant) oxidation reactions

Liu, Taizheng; Li, Qian; Xin, Ying; Zhang, Zhaoliang; Tang, Xingfu; Zheng, Lirong; Gao, Pu‐Xian

doi:10.1016/j.apcatb.2018.03.049

Cited by 97 publications

(57 citation statements)

References 67 publications

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“…As both soot and a catalyst are in a solid state, therefore the physical contact between them is key for a satisfactory catalytic activity in soot combustion. Regarding this particular aspect, it was confirmed that the activity of catalysts containing potassium was substantially improved due to the presence of mobile KO x species [7,8]. Other possible mechanisms is the formation of low-meltingpoint compounds, like KNO 3 , which also improve physical contact between soot and the catalyst [9].…”

Section: Introductionmentioning

confidence: 85%

Elucidation of Unexpectedly Weak Catalytic Effect of Doping with Cobalt of the Cryptomelane and Birnessite Systems Active in Soot Combustion

et al. 2019

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In this work the influence of cobalt doping on both properties and catalytic activity of cryptomelane and birnessite in soot combustion was investigated in detail. The investigated samples have been synthesized by a microwave-assisted hydrothermal method and cobalt was introduced in two ways-by impregnation or by addition to the precursor mixture before hydrothermal treatment. The obtained catalysts have been characterized by XRF, BET, XRD, RS, XPS and ATR-IR. Surprisingly, no distinct effect of cobalt presence on catalytic activity has been found. Most probably cobalt was localized in the position of manganese within the cryptomelane/birnessite structure or within segregated manganese-cobalt complex oxides, where its oxidation level was fixed. A series of reference manganese-cobalt mixed oxides (100-0% Mn) have been synthesized to elucidate this effect. These samples have been structurally characterized and thermal evolution of their structures was profoundly investigated. A high tendency of cobalt incorporation into the manganese oxide matrix and its subsequent stabilization in the spinel forms was proposed as an explanation of the observed lack of a promotional effect of this additive in soot combustion.

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Section: Introductionmentioning

confidence: 85%

Elucidation of Unexpectedly Weak Catalytic Effect of Doping with Cobalt of the Cryptomelane and Birnessite Systems Active in Soot Combustion

et al. 2019

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“…34 A study of the temperature-dependent ionic transport behavior of hollandite would be advantageous for the use of these materials in batteries, nuclear waste containment, catalysis, and other fields. 34 A study of the temperature-dependent ionic transport behavior of hollandite would be advantageous for the use of these materials in batteries, nuclear waste containment, catalysis, and other fields.…”

Section: Temperature-dependent Electrical Transport Propertiesmentioning

confidence: 99%

“…Potassium ions are located in the tunnel of hollanditetype titanium dioxide and behave like quasi-free cations for conduction. 34 A study of the temperature-dependent ionic transport behavior of hollandite would be advantageous for the use of these materials in batteries, nuclear waste containment, catalysis, and other fields. AC impedance is a good technique to evaluate and calculate the ionic conductivity in ionic conductors.…”

Section: Temperature-dependent Electrical Transport Propertiesmentioning

confidence: 99%

“…When Ba x Ti 8 O 16 was measured in the temperature range between −223 and 107°C, it showed a ground state that is dominated by the electron correlation effect and the coupling between the electronic structure and lattice distortion. 34 It appears that determining the electrical transport a narrow temperature range does not allow one to comprehend the relationship between the structure and carrier (ions or electrons) conduction and explore the potential applications of titanium-based hollandites. 34 It appears that determining the electrical transport a narrow temperature range does not allow one to comprehend the relationship between the structure and carrier (ions or electrons) conduction and explore the potential applications of titanium-based hollandites.…”

Section: Introductionmentioning

confidence: 99%

“…32,33 Recently, Liu et al found that K x Ti 8 O 16 combusted soot well in a temperature range from 100 to 700°C. 34 It appears that determining the electrical transport a narrow temperature range does not allow one to comprehend the relationship between the structure and carrier (ions or electrons) conduction and explore the potential applications of titanium-based hollandites. Therefore, examining the electrical transport property of titanium-based hollandites in a wider temperature range is required.…”

Section: Introductionmentioning

confidence: 99%

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Temperature‐dependent electrical transport behavior and structural evolution in hollandite‐type titanium‐based oxide

Feng

et al. 2019

J Am Ceram Soc

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Electrical transport behavior and structural characteristics directly determine the use of functional ceramic materials in electronic information storage, catalytic conversion, and energy field applications. However, these properties are poorly understood because most of the relevant experiments were performed in a rather narrow temperature range. Herein, we used hollandite‐type KxTi8O16 as an example to systematically study the temperature‐dependent structure and electrical transport properties in a wide temperature range from 25 to 900°C. The electrical transport involves both potassium ionic conduction and electronic conduction. With increasing temperature, the ionic conductivity increases below 800°C and decreases above 800°C. The electronic conductivity displays two maxima at 0.15 S/cm at 400°C and 5.2 × 10−4 S/cm at 800°C. These interesting variations in the conductivities are related to the presence of Ti3+ and the structural transformation from hollandite to a mixture of rutile and jeppeite. The findings reported herein support the potential application of titanium‐based hollandites and provide an understanding of the electrical transport properties of functional ceramic materials.

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Supported Metal Single‐Atom Thermocatalysts for Oxidation Reactions

Piccolo

Loridant

Christopher

2022

Supported Metal Single Atom Catalysis

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The interest in single-metal-atom dispersion in heterogeneous catalysis has existed since the 1950s with spectroscopic investigations of rhodium "single-site" catalysts supported on alumina, and more recently with oxometallate monomers for selective oxidation reactions. A decade ago, advances in electron microscopy intensified the interest of the catalysis community in controlling the dispersion of supported metals down to the single-atom active site level and revealing their intrinsic catalytic properties. Pioneering works in the ever-growing field of single-atom catalysis investigated late transition metals (group 8 to 11) supported on transition metal oxides for the CO oxidation and water-gas shift reactions. Since then, various single-atom catalysts, most often supported on oxides, have been evaluated in a broad panel of thermal oxidation reactions, and have often shown remarkable performances. Besides CO oxidation over oxidesupported noble metals, which represents the major part of the literature, this chapter reviews the main classes of oxidation reactions, including total and selective oxidations of hydrocarbons and oxygenates, on 2 oxide-or carbon-supported catalysts. Throughout the chapter, we emphasize several aspects that we consider important, such as the coordination environment and stability of single metal atoms, as well as their compared performance with supported nanoparticles. Figure 3. a) Aberration-corrected STEM image of Pt atoms (identified by yellow circles) on ca. 5 nm diameter anatase TiO2 particles. Adapted with permission from [72], Copyright 2017 ACS. b) CO probemolecule FTIR spectra of a Pt/TiO2 SAC as a function of temperature during a TPD measurement. c) DFT-calculated structure of CO bound to PtO2 adsorbed at a TiO2(145) step edge. b and c adapted with permission from [73], Copyright 2018 Elsevier. d) Schematic showing the structural transformation of isolated Pt species as a function of environmental conditions. Adapted with permission from [74],Copyright 2019 Springer Nature. e) DFT-calculated reaction pathway for CO oxidation on a Pd/TiO2 SAC that was supported by spectroscopic and kinetic analyses. Adapted with permission from [75],

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Quasi free K cations confined in hollandite-type tunnels for catalytic solid (catalyst)-solid (reactant) oxidation reactions

Cited by 97 publications

References 67 publications

Elucidation of Unexpectedly Weak Catalytic Effect of Doping with Cobalt of the Cryptomelane and Birnessite Systems Active in Soot Combustion

Elucidation of Unexpectedly Weak Catalytic Effect of Doping with Cobalt of the Cryptomelane and Birnessite Systems Active in Soot Combustion

Temperature‐dependent electrical transport behavior and structural evolution in hollandite‐type titanium‐based oxide

Supported Metal Single‐Atom Thermocatalysts for Oxidation Reactions

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