On the stability of mixed M2+/M3+ oxides

Olsbye, Unni; Akporiaye, Duncan; Rytter, Erling; Rønnekleiv, Morten; Tangstad, Elisabeth

doi:10.1016/s0926-860x(01)00740-2

Cited by 41 publications

(18 citation statements)

References 4 publications

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“…65-0476) at 2θ of 36.94°, 42.92°, and 62.30°, corresponding to crystal lattice indices of (111), (200), and (220), respectively. No peaks indicative of Al2O3 species was detected in either MgAl-LDO or VMT-LDO, these observations suggested that Al2O3 was in an amorphous state or that Al 3+ ions became incorporated into MgO to form spinel phases, such as MgAl2O4 [28][29][30]. The SEM and TEM images of the as-obtained LDOs are displayed in Figure 2.…”

Section: Xrdsem and Tem Characterization Of Ldhs And Ldosmentioning

confidence: 95%

“…The diffraction peaks indicated that the LDH was successfully synthesized by using the spent liquor after mixed dilute aqua regia solution etching of vermiculite. After calcining at 550 • C for 5 h in a muffle furnace, the as-obtained MgAl-LDO and VMT-LDO (Figure 1b) [28][29][30]. The SEM and TEM images of the as-obtained LDOs are displayed in Figure 2.…”

Section: Xrd Sem and Tem Characterization Of Ldhs And Ldosmentioning

confidence: 99%

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Two-Dimensional Layered Double Hydroxide Derived from Vermiculite Waste Water Supported Highly Dispersed Ni Nanoparticles for CO Methanation

Zhu

Tian

et al. 2017

Catalysts

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Expanded multilayered vermiculite (VMT) was successfully used as catalyst support and Ni/VMT synthesized by microwave irradiation assisted synthesis (MIAS) exhibited excellent performance in our previous work. We also developed a two-dimensional porous SiO 2 nanomesh (2D VMT-SiO 2 ) by mixed-acid etching of VMT. Compared with three-dimensional (3D) MCM-41, 2D VMT-SiO 2 as a catalyst support provided a superior position for implantation of NiO species and the as-obtained catalyst exhibited excellent performance. In this paper, we successfully synthesized a layered double hydroxide (LDH) using the spent liquor after mixed-acid etching of VMT, which mainly contained Mg 2+ and Al 3+ . The as-calcined layered double oxide (LDO) was used as a catalyst support for CO methanation. Compared with Ni/MgAl-LDO, Ni/VMT-LDO had smaller active component particles; therefore, in this study, it exhibited excellent catalytic performance over the whole temperature range of 250-500 • C. Ni/VMT-LDO achieved the best activity with 87.88% CO conversion, 89.97% CH 4 selectivity, and 12.47 × 10 −2 ·s −1 turn over frequency (TOF) at 400 • C under a gas hourly space velocity of 20,000 mL/g/h. This study demonstrated that VMT-LDO as a catalyst support provided an efficient way to develop high-performance catalysts for synthetic natural gas (SNG) from syngas.

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Section: Xrdsem and Tem Characterization Of Ldhs And Ldosmentioning

confidence: 95%

Section: Xrd Sem and Tem Characterization Of Ldhs And Ldosmentioning

confidence: 99%

Two-Dimensional Layered Double Hydroxide Derived from Vermiculite Waste Water Supported Highly Dispersed Ni Nanoparticles for CO Methanation

Zhu

Tian

et al. 2017

Catalysts

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“…The stabilizing effect is helpful to resist sintering of the catalysts under the severe combustion conditions. Olsbye [41] and Pérez-Ramírez [34] …”

Section: Tpr Analysis Of Xcomao-800 Catalystsmentioning

confidence: 99%

Catalytic combustion of methane over mixed oxides derived from Co–Mg/Al ternary hydrotalcites

Jiang

Cheng

et al. 2010

Fuel Processing Technology

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Co x Mg 3 − x /Al composite oxides (xCoMAO-800) were prepared by calcination of Co x Mg 3 − x /Al hydrotalcites (x = 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, respectively) at 800°C. The materials were characterized using XRD, TG-DSC, N 2 adsorption-desorption and TPR. The methane catalytic combustion over the xCoMAO-800 was assessed in a fixed bed micro-reactor. The results revealed that cobalt can be homogenously dispersed into the matrices of the hydrotalcites and determines the structure, specific surface areas and porosity of the derived xCoMAO-800 oxide catalysts. The thermal stability and homogeneity of the hydrotalcites markedly depends on the cobalt concentration in the hydrotalcites. The Co-based hydrotalcite-derived oxides exhibit good activity in the catalytic combustion of methane. The catalytic activity over the xCoMAO-800 oxides enhances with increasing x up to 1.5, but subsequently decreases dramatically as cobalt loadings are further increased. The 1.5CoMAO-800 catalyst shows the best methane combustion activity, igniting methane at 450°C and completing methane combustion around 600°C. The catalytic combustion activity over the xCoMAO-800 oxides are closely related to the strong Co-Mg/Al interaction within the mixed oxides according to the TG-DSC, TPR and activity characteristics.© 2009 Elsevier B.V. All rights reserved.The catalytic combustion of methane has attracted intensive interests in the past few decades, due to its higher energy conversion efficiency and ultra-low emissions of environmental pollutants, such as NO x , CO, and unburned hydrocarbons [1][2][3][4][5][6]. In addition, catalytic combustion of lean methane gas to abate methane emission also has wide-ranging applications [5,7]. For the effective and stable catalytic combustion process, suitable catalysts play a crucial role. Generally, supported noble metal oxides, particularly palladium oxide, are excellent catalysts for lower temperature combustion, but noble metals are expensive and prone to deactivation owing to sintering, decomposition and undesirable interaction with supports under hydrothermal situations encountered in combustion [3,6,[8][9][10]. A variety of inexpensive transition metal oxide catalysts, such as solid solution oxides [11][12][13], perovskites [14][15][16], pyrochlores [17][18][19] and hexaaluminates [7,[20][21][22] have been explored for catalytic combustion of methane. Unfortunately, no single catalyst, so far, can tolerate the stringent hydrothermal conditions existing in methane combustion. Obviously, the further development of new combustion catalysts is indispensable. Currently, multi-staged combustion methodology are used to overcome the drawbacks of the current catalysts for catalytic combustion [2,3], in which the catalysts of high surface area and activity are highly desired to ignite methane at lower temperatures and sustain stable combustion at high temperatures.Among the transition metal oxide catalysts, cobalt-based oxides are ones of the most active catalysts in catalytic methane combustion, and Co...

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“…Mg(Al)O, prepared via the corresponding hydrotalcite phase, possesses excellent properties as support material for metal-based catalysts [5,[6][7][8][9][10]. The support material is particularly suited for applications in an intermediate temperature range (≤ 600°C), where it has been shown to maintain a high surface area (above 100 m 2 /g) even after 14 days in a steam-rich atmosphere [11]. Propane dehydrogenation to propene is one reaction for which the intermediate temperature range is particularly suited, and Pt,Sn/Mg(Al)O has been shown to possess superior activity and stability for this reaction compared to conventional Pt,Sn/Al 2 O 3 catalysts [7].…”

Section: Introductionmentioning

confidence: 99%

In situ XPS investigation of Pt(Sn)/Mg(Al)O catalysts during ethane dehydrogenation experiments

et al. 2007

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Calcined hydrotalcite with or without added metal (Mg(Al)O, Pt/Mg(Al)O and Pt,Sn/Mg(Al)O) have been investigated with in situ X-ray Photoelectron Spectroscopy (XPS) during ethane dehydrogenation experiments. The temperature in the analysis chamber was 450ºC and the gas pressure was in the range 0.3 -1 mbar. Depth profiling of calcined hydrotalcite and platinum catalysts under reaction, oxidation and in hydrogenwater mixture was performed by varying the photon energy, covering an analysis depth of 10-21 Å. It was observed that the Mg/Al ratio in the Mg(Al)O crystallites does not vary significantly in the analysis depth range studied. This result indicates that Mg and Al are homogeneously distributed in the Mg(Al)O crystallites. Catalytic tests have shown that the initial activity of a Pt,Sn/Mg(Al)O catalyst increases during an activation period consisting of several cycles of reduction -dehydrogenation -oxidation. The Sn/Mg ratio in a Pt,Sn/Mg(Al)O catalyst was followed during several such cycles, and was found to increase during the activation period, probably due to a process where tin spreads over the carrier material and covers an increasing fraction of the Mg(Al)O surface. The results further indicate that spreading of tin occurs under reduction conditions. A PtSn 2 alloy was studied separately. The surface of the alloy was enriched in Sn during reduction and reaction conditions at 450°C. Binding energies were determined and indicated that Sn on the particle surface is predominantly in an oxidized state under reaction conditions, while Pt and a fraction of Sn is present as a reduced Pt-Sn alloy.

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On the stability of mixed M2+/M3+ oxides

Cited by 41 publications

References 4 publications

Two-Dimensional Layered Double Hydroxide Derived from Vermiculite Waste Water Supported Highly Dispersed Ni Nanoparticles for CO Methanation

Two-Dimensional Layered Double Hydroxide Derived from Vermiculite Waste Water Supported Highly Dispersed Ni Nanoparticles for CO Methanation

Catalytic combustion of methane over mixed oxides derived from Co–Mg/Al ternary hydrotalcites

In situ XPS investigation of Pt(Sn)/Mg(Al)O catalysts during ethane dehydrogenation experiments

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