Catalytic properties of spinel-type complex oxides in oxidation reactions

Pirogova, G. N.; Panich, N. M.; Korosteleva, R. I.; Tyurkin, Yu. V.; Voronin, Yu. V.

doi:10.1007/bf00703476

Cited by 11 publications

(5 citation statements)

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“…Generally, a higher temperature leads to a better specific activity, with the best reaction rate of 9.32 × 10 –5 mol m –2 min –1 achieved by ZnMn 0.2 Co 1.8 O 4 ( x = 0.2) at 448 K. An increased availability of bulk oxygen at higher temperatures seems to be responsible for the variations at different temperatures. Furthermore, the stability test of ZnMn 0.2 Co 1.8 O 4 in Figure S3 indicates the superior stability of the oxide catalyst, which decreases only ∼8% after reaction for 24 h. Notably, this excellent activity is comparable to or better than those of most of the reported transition metal spinel oxides or mixed oxide catalysts such as spinel Co 3 O 4 powder, MnCuO x , CuCo 2 O x , MnCr 2 O 4 , Co 1– x Cu x Mn 2 O 4 , and La 1– x Ce x CoO 3 perovskite . It even approaches those of some spinel nanomaterials, for instance, the M x Co 3– x O 4 (M = Co, Ni, or Zn) nanoarrays that have been reported.…”

Section: Resultsmentioning

confidence: 76%

Identifying Influential Parameters of Octahedrally Coordinated Cations in Spinel ZnMn_xCo_2–xO₄ Oxides for the Oxidation Reaction

et al. 2018

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Transition metal oxides are of potential alternatives to precious metal catalysts for oxidation reactions. Among these earth abundant oxide catalysts, cobalt-or manganese-based spinel oxides have gained consistent interests due to their superior catalytic performances. It has been found that the octahedral sites in spinels are responsible for their catalytic activities. However, little is known to date about the parameters of the octahedrally coordinated cations that influence their activity. Herein, a series of ZnMnxCo2-xO4 (x=0~2.0) spinel oxides are investigated, employing CO oxidation as the model reaction, with the particular attention on the activity variation caused by tuning the ratio of octahedrally occupied Mn to Co. Both Mn and Co contribute to the activity with Mn cations as the primary active species when they co-exist, the intrinsic specific activity is found composition-dependence and the highest activity is given by the Mn/Co molar ratio of 0.11. The presence of Mn 4+ and Mn 3+ in a proper ratio is another key for achieving high oxidation activity and can be rationalized by the moderate oxygen adsorption during the CO oxidation, which facilitates the O vacancy refilling. This is also supported by the density function theory (DFT) calculation, showing that the high activity of ZnMn0.2Co1.8O4 originates from having the O p-band center neither too far nor too close to the Fermi level. The eg occupancy of Mn cations and the O p-band center relative to the Fermi level, which are the indexes of how the electronic structure influences the oxygen addition-and removal-related processes, are proposed to serve as the activity descriptors. This work may provide a different insight into the understanding of the activity of transition metal spinel oxides for oxidation reactions.

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Section: Resultsmentioning

confidence: 76%

Identifying Influential Parameters of Octahedrally Coordinated Cations in Spinel ZnMn_xCo_2–xO₄ Oxides for the Oxidation Reaction

et al. 2018

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“…It is reported that the better the adsorptive properties, the higher the catalytic activity in spinel-type oxide complexes in oxidation reactions. 42 Among VOCs, formaldehyde has a relatively high dipole moment compared to ethanol, acetone, and benzene. Therefore, ZnCo 2 O 4 can strongly chemisorb formaldehyde, resulting in high selectivity for formaldehyde against other VOCs.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…In comparison with Co 3 O 4 , an increase of the Zn content in ZnCo 2 O 4 largely increases the hole concentration, which may strongly adsorb gas molecules with high dipole moments. It is reported that the better the adsorptive properties, the higher the catalytic activity in spinel-type oxide complexes in oxidation reactions . Among VOCs, formaldehyde has a relatively high dipole moment compared to ethanol, acetone, and benzene.…”

Section: Resultsmentioning

confidence: 99%

Nonstoichiometric Co-rich ZnCo₂O₄ Hollow Nanospheres for High Performance Formaldehyde Detection at ppb Levels

Park

Kim

Choi

et al. 2016

ACS Appl. Mater. Interfaces

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Since metal oxide semiconductors were investigated as chemiresistors, rapid advances have been reported in this field. However, better performance metrics are still required, such as higher sensitivity and selectivity levels for practical applications. To improve the sensing performance, we discuss an optimal composition of the active sensing material, nonstoichiometric Co-rich ZnCo2O4, prepared by the partial substitution of Co(2+) into Zn(2+) in Co3O4 without altering a hollow sphere morphology. Remarkably, this Co-rich ZnCo2O4 phase achieved detection limits for formaldehyde as low as 13 ppb in experimental measurements and 2 ppb in theory, which were the lowest values ever reported from actual measurements at a working temperature of 225 °C. It was also unprecedented that the selectivity for formaldehyde was greatly enhanced with respect to the selectivity levels against other volatile organic compounds (VOCs). These excellent sensing performances are due to the optimal composition of the Co-rich ZnCo2O4 material with a proper hole concentration and well-organized conductive network.

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“…The most active catalysts are those containing ions of Co, Cu, Mn, Ni or Cr [2]. Table 1 presents systems in which we applied SHS and shows principal phases which emerged during the synthesis.…”

Section: Resultsmentioning

confidence: 99%

Self-propagating high-temperature synthesis in the production of catalysts and supports

Tyurkin

Chesalov

Luzhkova

1997

React Kinet Catal Lett

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Catalytic properties of spinel-type complex oxides in oxidation reactions

Cited by 11 publications

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Identifying Influential Parameters of Octahedrally Coordinated Cations in Spinel ZnMn_xCo_2–xO₄ Oxides for the Oxidation Reaction

Identifying Influential Parameters of Octahedrally Coordinated Cations in Spinel ZnMn_xCo_2–xO₄ Oxides for the Oxidation Reaction

Nonstoichiometric Co-rich ZnCo₂O₄ Hollow Nanospheres for High Performance Formaldehyde Detection at ppb Levels

Self-propagating high-temperature synthesis in the production of catalysts and supports

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Catalytic properties of spinel-type complex oxides in oxidation reactions

Cited by 11 publications

References 0 publications

Identifying Influential Parameters of Octahedrally Coordinated Cations in Spinel ZnMnxCo2–xO4 Oxides for the Oxidation Reaction

Identifying Influential Parameters of Octahedrally Coordinated Cations in Spinel ZnMnxCo2–xO4 Oxides for the Oxidation Reaction

Nonstoichiometric Co-rich ZnCo2O4 Hollow Nanospheres for High Performance Formaldehyde Detection at ppb Levels

Self-propagating high-temperature synthesis in the production of catalysts and supports

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Identifying Influential Parameters of Octahedrally Coordinated Cations in Spinel ZnMn_xCo_2–xO₄ Oxides for the Oxidation Reaction

Identifying Influential Parameters of Octahedrally Coordinated Cations in Spinel ZnMn_xCo_2–xO₄ Oxides for the Oxidation Reaction

Nonstoichiometric Co-rich ZnCo₂O₄ Hollow Nanospheres for High Performance Formaldehyde Detection at ppb Levels