Effect of support composition and metal loading on Au catalyst activity in steam reforming of methanol

Pojanavaraphan, Chinchanop; Luengnaruemitchai, Apanee; Gülari, Erdogan

doi:10.1016/j.ijhydene.2012.06.107

Cited by 37 publications

(18 citation statements)

References 64 publications

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“…This is not surprising since the expected oxidation state of Fe 3+ also should enhance oxygen vacancy formation according to Equation (3), assuming that Fe 3+ (crystal radius VIII = 0.092 nm [16]) substitutes for Ce 4+ (crystal radius VIII = 0.111 nm [16]). Although the mismatch is~17%, which is slightly higher than that suggested for extensive solid solubility (15%) [17], the formation of Ce y Fe 1−y O 2−x solid solution has been reported previously [33,34]. However, the substitution of Ce 3+ by Fe 3+ is much less likely owing to the large size of the former (crystal radius VIII = 0.1283 nm [16]) and the associated~28% mismatch.…”

Section: Water Absorptionmentioning

confidence: 78%

Aqueous and Surface Chemistries of Photocatalytic Fe-Doped CeO2 Nanoparticles

et al. 2017

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Abstract:The present work describes the effects of water on Fe-doped nanoparticulate CeO 2 , produced by flame spray pyrolysis, which represent a critical environmental issue because CeO 2 is not stable in typical atmospheric conditions. It is hygroscopic and absorbs~29 wt % water in the bulk when exposed to water vapor but, more importantly, it forms a hydrated and passivating surface layer when immersed in liquid water. In the latter case, CeO 2 initially undergoes direct and/or reductive dissolution, followed by the establishment of a passivating layer calculated to consist of~69 mol % solid CeO 2 ·2H 2 O and~30 mol % gelled Ce(OH) 4 . Under static flow conditions, a saturated boundary layer also forms but, under turbulent flow conditions, this is removed. While the passivating hydrated surface layer, which is coherent probably owing to the continuous Ce(OH) 4 gel, would be expected to eliminate the photoactivity, this does not occur. This apparent anomaly is explained by the calculation of (a) the thermodynamic stability diagrams for Ce and Fe; (b) the speciation diagrams for the Ce 4+ -H 2 O, Ce 3+ -H 2 O, Fe 3+ -H 2 O, and Fe 2+ -H 2 O systems; and (c) the Pourbaix diagrams for the Ce-H 2 O and Fe-H 2 O systems. Furthermore, consideration of the probable effects of the localized chemical and redox equilibria owing to the establishment of a very low pH (<0) at the liquid-solid interface also is important to the interpretation of the phenomena. These factors highlight the critical importance of the establishment of the passivating surface layer and its role in photocatalysis. A model for the mechanism of photocatalysis by the CeO 2 component of the hydrated phase CeO 2 ·2H 2 O is proposed, explaining the observation of the retention of photocatalysis following the apparent alteration of the surface of CeO 2 upon hydration. The model involves the generation of charge carriers at the outer surface of the hydrated surface layer, followed by the formation of radicals, which decompose organic species that have diffused through the boundary layer, if present.

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Section: Water Absorptionmentioning

confidence: 78%

Aqueous and Surface Chemistries of Photocatalytic Fe-Doped CeO2 Nanoparticles

et al. 2017

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“…Hence, the reactions taking place during the steam reforming process of bio-oil can be described by Eq. (1), similar to the description of the industrial process of methanol reforming for hydrogen production [41].…”

Section: Calculation Methodsmentioning

confidence: 99%

Hydrogen production from catalytic reforming of the aqueous fraction of pyrolysis bio-oil with modified Ni–Al catalysts

Yao

Yang

et al. 2014

International Journal of Hydrogen Energy

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“…550 • C) [63,64]. In CeFe, reduction of iron species overlap with the reduction features of ceria and four peaks are distinguished: the first one at around 350 • C was related to the reduction of hematite to magnetite state; the second and third peaks at around 450 • C and 600 • C can be attributed to the surface reduction of Ce 4+ and the reduction of Fe 2+ to Fe, while the last signal at 825 • C can be associated with the reduction of bulk ceria [65,66].…”

Section: Reduction Behaviourmentioning

confidence: 99%

The Effect of Sr Addition in Cu- and Fe-Modified CeO2 and ZrO2 Soot Combustion Catalysts

Rico-Pérez¹,

Aneggi²,

Trovarelli³

2017

Catalysts

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This study investigates the activity of transition and alkaline-earth metal-doped catalysts supported on ceria or zirconia for the NO x -assisted oxidation of diesel particulate. A series of Cu-and Fe-impregnated catalysts over CeO 2 and ZrO 2 supports were prepared by incipient wetness impregnation and characterized by BET, X-ray diffraction (XRD), and temperature-programmed reduction (TPR) experiments while their catalytic activity was investigated in NO x -assisted reaction by means of temperature programmed oxidation experiments (TPO). Higher activity was achieved by copper modified catalysts; the addition of Sr positively affected the performance of the materials, suggesting a synergic effect between transition metals and alkaline-earth metal. The role of copper is correlated to the oxidation of NO to NO 2 , while strontium seems to be mainly involved in the storage of NO x species.

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Effect of support composition and metal loading on Au catalyst activity in steam reforming of methanol

Cited by 37 publications

References 64 publications

Aqueous and Surface Chemistries of Photocatalytic Fe-Doped CeO2 Nanoparticles

Aqueous and Surface Chemistries of Photocatalytic Fe-Doped CeO2 Nanoparticles

Hydrogen production from catalytic reforming of the aqueous fraction of pyrolysis bio-oil with modified Ni–Al catalysts

The Effect of Sr Addition in Cu- and Fe-Modified CeO2 and ZrO2 Soot Combustion Catalysts

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