Reactions of carbon monoxide and nitric oxide over La2-xA'xCu1-yB'yO4. A potassium tetrafluoronickelate (K2NiF4)-type mixed oxide

Mizuno, Noritaka; Yamato, Mika; Tanaka, Mika; Misono, Makoto

doi:10.1021/cm00002a013

Cited by 35 publications

(21 citation statements)

References 4 publications

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“…54 The α of the present Sr 2 TiO 4 (α(Sr 2 TiO 4 ) = (2α a + α c )/3 = 12.39(2) × 10 −6 K −1 (298−1273 K)) is also higher than that of perovskite-type oxide with a similar composition SrTiO 3 (α(SrTiO 3 ) = α a = 10.80(8) × 10 −6 K −1 (300−1235 K)). 55 The same relation (α(A 2 BO 4 ) > α(ABO 3 )) is also valid for CaErAlO 4 28 and CaYAlO 4 . 29 This discrepancy between our results (α(A 2 BO 4 ) > α(ABO 3 )) in this work and in refs 28 and 29 and the previous work (α(A 2 BO 4 ) < α(ABO 3 )) 53 is attributable to the chemical expansion in perovskite-type transition metal oxides ABO 3 in the literature: 56 the change of transition-metal-cation B n+ valence n+ (e.g., B = Fe and Co) and oxygen content 3−δ in ABO 3−δ with temperature.…”

Section: Inorganic Chemistrysupporting

confidence: 54%

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Structural Origin of the Anisotropic and Isotropic Thermal Expansion of K₂NiF₄-Type LaSrAlO₄ and Sr₂TiO₄

Kawamura¹,

Yashima²,

Fujii³

et al. 2015

Inorg. Chem.

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K2NiF4-type LaSrAlO4 and Sr2TiO4 exhibit anisotropic and isotropic thermal expansion, respectively; however, their structural origin is unknown. To address this unresolved issue, the crystal structure and thermal expansion of LaSrAlO4 and Sr2TiO4 have been investigated through high-temperature neutron and synchrotron X-ray powder diffraction experiments and ab initio electronic calculations. The thermal expansion coefficient (TEC) along the c-axis (αc) being higher than that along the a-axis (αa) of LaSrAlO4 [αc = 1.882(4)αa] is mainly ascribed to the TEC of the interatomic distance between Al and apical oxygen O2 α(Al-O2) being higher than that between Al and equatorial oxygen O1 α(Al-O1) [α(Al-O2) = 2.41(18)α(Al-O1)]. The higher α(Al-O2) is attributed to the Al-O2 bond being longer and weaker than the Al-O1 bond. Thus, the minimum electron density and bond valence of the Al-O2 bond are lower than those of the Al-O1 bond. For Sr2TiO4, the Ti-O2 interatomic distance, d(Ti-O2), is equal to that of Ti-O1, d(Ti-O1) [d(Ti-O2) = 1.0194(15)d(Ti-O1)], relative to LaSrAlO4 [d(Al-O2) = 1.0932(9)d(Al-O1)]. Therefore, the bond valence and minimum electron density of the Ti-O2 bond are nearly equal to those of the Ti-O1 bond, leading to isotropic thermal expansion of Sr2TiO4 than LaSrAlO4. These results indicate that the anisotropic thermal expansion of K2NiF4-type oxides, A2BO4, is strongly influenced by the anisotropy of B-O chemical bonds. The present study suggests that due to the higher ratio of interatomic distance d(B-O2)/d(B-O1) of A2(2.5+)B(3+)O4 compared with A2(2+)B(4+)O4, A2(2.5+)B(3+)O4 compounds have higher α(B-O2), and A2(2+)B(4+)O4 materials exhibit smaller α(B-O2), leading to the anisotropic thermal expansion of A2(2.5+)B(3+)O4 and isotropic thermal expansion of A2(2+)B(4+)O4. The "true" thermal expansion without the chemical expansion of A2BO4 is higher than that of ABO3 with a similar composition.

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Section: Inorganic Chemistrysupporting

confidence: 54%

“…The crystal structure of a K 2 NiF 4 -type oxide A 2 BO 4 , such as LaSrAlO 4 and Sr 2 TiO 4 , consists of the alternate stacking of rocksalt AO-and perovskite ABO 3 -layers ( Figure 1). Here, A and B are larger and smaller cations, respectively.…”

Section: Introductionmentioning

confidence: 99%

Structural Origin of the Anisotropic and Isotropic Thermal Expansion of K₂NiF₄-Type LaSrAlO₄ and Sr₂TiO₄

Kawamura¹,

Yashima²,

Fujii³

et al. 2015

Inorg. Chem.

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“…With the substitutions at 'A' and/or 'B' site with different valence elements creates valences and vacancies, which helps in controlling the mechanism of a reaction. This tailoring possibility with perovskite structure has been used and several compositions have been reported for NO reduction using hydrocarbons or CO as reducing agent [16][17][18][19][20][21][22]. Particularly in the case of three-way catalysis for auto-exhaust emission reduction, perovskite shows activity by participation of lattice oxygen for oxidation and selectively taking oxygen from NO x for filling back the oxygen vacancy formed.…”

Section: Introductionmentioning

confidence: 99%

Nitric Oxide Reduction Using Hydrogen Over Perovskite Catalysts with Promotional Effect of Platinum on Catalytic Activity

et al. 2008

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The catalytic activities of strontium substituted La 0.7 Sr 0.3 MnO 3 type perovskite catalysts for NO reduction using H 2 as reducing agent has been studied, which is further improved by incorporation of Pt outside (0.1 wt.%Pt/ La 0.7 Sr 0.3 MnO 3 ) and inside (La 0.7 Sr 0.3 Mn 0.97 Pt 0.03 O 3 ) the perovskite lattice structure. Pt shows excellent enhancement in catalytic selectivity towards N 2 when supported on the perovskite. The catalysts were characterized using thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and specific surface area. Catalysts evaluations were carried out using thermo-gravimetric analysis coupled with mass spectra (TG-MS).

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“…A seguir serão apresentados os resultados obtidos durante a preparação, caracterização e ensaios catalíticos. A Tabela apresenta os resultados da área superficial específica dos catalisadores preparados neste trabalho, pelo método da coprecipitação, e os resultados de áreas superficiais obtidas por outros autores utilizando-se diferentes métodos [16,43,44,54].…”

Section: Capítulo V -Resultados E Discussõesunclassified

“…Outro fator importante é o tempo e a temperatura de calcinação. Dai et al [39], utilizaram 10 a 12 horas de calcinação, porém, de acordo com Mizuno et al [43], e Liu et al [51], sob condições mais brandas como neste trabalho, 800 o C durante 4 horas, foi possível obter óxidos puros e cristalinos.…”

Section: -Preparação Dos Catalisadoresunclassified

"Óxidos do tipo Perovskitas para reações de decomposição direta de NO e redução de NO com CO"

Tanabe¹

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À Professora Elisabete Assaf, pela orientação, ensinamento e incentivo à pesquisa, e ao professor Mansur Assaf, pelo auxílio e oportunidade de desenvolver trabalhos no Departamento de Engenharia Química da UFSCar. À Alessandra por estar sempre bem humorada e disposta a ajudar, com opiniões e discussões. Ao Jorge pelo happy-hour e pela grande amizade. Ao quarteto fantástico Rudge, Jorge, Bambi e Letícia pela conquista do título de vôlei Intra-Lab. À Letícia por acalmar o grupo ouvindo música "Country" no laboratório. À Thaísa pela diversão e ótima companhia de viagem em congressos. À Lidiane pela calma, e por sempre aceitar os convites "para a próxima". Ao Boiadeiro pelas trapalhadas e diversões, "faça o que eu digo e não faça o que eu faço".

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Reactions of carbon monoxide and nitric oxide over La2-xA'xCu1-yB'yO4. A potassium tetrafluoronickelate (K2NiF4)-type mixed oxide

Cited by 35 publications

References 4 publications

Structural Origin of the Anisotropic and Isotropic Thermal Expansion of K₂NiF₄-Type LaSrAlO₄ and Sr₂TiO₄

Structural Origin of the Anisotropic and Isotropic Thermal Expansion of K₂NiF₄-Type LaSrAlO₄ and Sr₂TiO₄

Nitric Oxide Reduction Using Hydrogen Over Perovskite Catalysts with Promotional Effect of Platinum on Catalytic Activity

"Óxidos do tipo Perovskitas para reações de decomposição direta de NO e redução de NO com CO"

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Reactions of carbon monoxide and nitric oxide over La2-xA'xCu1-yB'yO4. A potassium tetrafluoronickelate (K2NiF4)-type mixed oxide

Cited by 35 publications

References 4 publications

Structural Origin of the Anisotropic and Isotropic Thermal Expansion of K2NiF4-Type LaSrAlO4 and Sr2TiO4

Structural Origin of the Anisotropic and Isotropic Thermal Expansion of K2NiF4-Type LaSrAlO4 and Sr2TiO4

Nitric Oxide Reduction Using Hydrogen Over Perovskite Catalysts with Promotional Effect of Platinum on Catalytic Activity

"Óxidos do tipo Perovskitas para reações de decomposição direta de NO e redução de NO com CO"

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Product

Resources

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Structural Origin of the Anisotropic and Isotropic Thermal Expansion of K₂NiF₄-Type LaSrAlO₄ and Sr₂TiO₄

Structural Origin of the Anisotropic and Isotropic Thermal Expansion of K₂NiF₄-Type LaSrAlO₄ and Sr₂TiO₄