Nanosized gold catalysts supported on ceria and ceria-alumina for WGS reaction: Influence of the preparation method

Andreeva, D.; Ivanov, Ivan B.; Ilieva, L.; Sobczak, Janusz W.; Avdeev, G; Tabakova, T.

doi:10.1016/j.apcata.2007.04.011

Cited by 39 publications

(20 citation statements)

References 21 publications

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“…Again, Raman peak shift towards lower wavenumber indicates the generation of tensile stresses in the material by Eq. (11). This estimation of stress generation from Raman shift follows the same trend as revealed by the XRD results i.e., initial shift is towards lower value which subsequently starts to shift towards higher values.…”

Section: Raman Spectroscopysupporting

confidence: 50%

“…CeO 2 is one of the most important rare-earth oxides, having numerous applications, such as in catalysis [11], fuel cells [12], polishing materials [13], oxygen gas sensors [14], optical devices [15]. Thus, nanocrystalline ceria has an important role in enhancing macroscopic properties, using its aliovalent tendency, tailoring crystallite sizes, and manipulating the surface area for these applications [16,17].…”

Section: Introductionmentioning

confidence: 99%

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Non-monotonic lattice parameter variation in ball-milled ceria

2015

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High-energy ball milling is utilized in creating microstructural changes (such as change in lattice parameter, lattice strain) within micro-ceria, which were quantified using line profile analysis by X-ray diffraction. Crystallite size significantly decreased from 85 to 11 nm when subjected to 4 h of high-energy ball milling, and then remained same with increase in milling duration (up to 16 h of milling). Three different methods, namely NelsonRiley function, Cohen's method, and Pawley fitting, were used to calculate the lattice parameter and a lattice expansion from 5.4082 to 5.4147 Å was observed for a duration of 0 up to 12 h. The effect of milling on generation of residual strain and the probability of stacking fault in affecting the lattice parameter are delineated in the current work. Non-monotonic change of lattice parameter with saturation of crystallite size is attributed to the vacancy-induced stresses that generate at inter-crystallite regions and render excessive free volume during high-energy ball milling.

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Section: Raman Spectroscopysupporting

confidence: 50%

Section: Introductionmentioning

confidence: 99%

Non-monotonic lattice parameter variation in ball-milled ceria

2015

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“…This may be ascribed to the easier accessibility of reactants to the Ni sites. Finally, the CO 2 /CO ratio among the gaseous products is increased by the presence of CeO 2 , since it favors the water-gas shift reaction [33,34]. The results shown in Table 4 indicate that coke formation occurs at a much higher rate on Zr-modified catalysts, because, as explained above, the acid sites joined with the presence of Zr promote ethanol dehydration to ethylene, which acts as a hard precursor for carbon deposition [35].…”

Section: Characterization Of Ce-or Zr-modified Ni/sio 2 Catalystsmentioning

confidence: 49%

Effect of Ce and Zr Addition to Ni/SiO2 Catalysts for Hydrogen Production through Ethanol Steam Reforming

et al. 2015

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A series of Ni/Ce x Zr 1−x O 2 /SiO 2 catalysts with different Zr/Ce mass ratios were prepared by incipient wetness impregnation. Ni/SiO 2 , Ni/CeO 2 and Ni/ZrO 2 were also prepared as reference materials to compare. Catalysts' performances were tested in ethanol steam reforming for hydrogen production and characterized by XRD, H 2 -temperature programmed reduction (TPR), NH 3 -temperature programmed desorption (TPD), TEM, ICP-AES and N 2 -sorption measurements. The Ni/SiO 2 catalyst led to a higher hydrogen selectivity than Ni/CeO 2 and Ni/ZrO 2 , but it could not maintain complete ethanol conversion due to deactivation. The incorporation of Ce or Zr prior to Ni on the silica support resulted in catalysts with better performance for steam reforming, keeping complete ethanol conversion over time. When both Zr and Ce were incorporated into the catalyst, Ce x Zr 1−x O 2 solid solution was formed, as confirmed by XRD analyses. TPR results revealed stronger Ni-support interaction in the Ce x Zr 1−x O 2 -modified catalysts than in Ni/SiO 2 one, which can be attributed to an increase of the dispersion of Ni species. All of the Ni/Ce x Zr 1−x O 2 /SiO 2 catalysts exhibited good catalytic activity and stability after 8 h of time on stream at 600• C . The best catalytic performance in terms of hydrogen selectivity was achieved when the Zr/Ce mass ratio was three.

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“…However the low temperature reduction processes are shifted towards lower temperatures in all the cases. In fact, the presence of gold is often reported to facilitate the H2 mobility and also to weaken the Ce-O bond due to the electronic transfer between the oxide and the noble metal resulting in an overall improved reducibility [63,64]. Moreover, as stated by Jacobs et al [65] the enhanced support reduction in noble metal-ceria systems not only involves the shifting of the reduction processes to lower temperature, but also the extent of reduction.…”

Section: Uv-vismentioning

confidence: 86%

WGS and CO-PrOx reactions using gold promoted copper-ceria catalysts: “Bulk CuO CeO2 vs. CuO CeO2/Al2O3 with low mixed oxide content”

Reina

Ivanova

Laguna

et al. 2016

Applied Catalysis B: Environmental

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A copper-ceria bulk catalyst has been compared to a series of catalysts designed according to the as called "supported approach", corresponding to the dispersion of low content mixed copper-ceria oxide on alumina matrix. The principal characteristics of both types of catalysts are contemplated and the differences in their electronic and redox properties discussed in details. As a plus, the gold metal promotion of the catalysts is also envisaged. The advantages of the systems in the CO clean up reactions, WGS and CO-PrOx are commented. While the WGS activity appears to be ruled especially by the Cu/Ce surface to volume ratio, the CO-PrOx reaction is governed by the CuO loading. Gold addition provides benefits only at the low temperature WGS regime. Very importantly, the supported systems are always superior to the bulk configuration in terms of specific activity, a key factor from the catalyst's design perspective.

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Nanosized gold catalysts supported on ceria and ceria-alumina for WGS reaction: Influence of the preparation method

Cited by 39 publications

References 21 publications

Non-monotonic lattice parameter variation in ball-milled ceria

Non-monotonic lattice parameter variation in ball-milled ceria

Effect of Ce and Zr Addition to Ni/SiO2 Catalysts for Hydrogen Production through Ethanol Steam Reforming

WGS and CO-PrOx reactions using gold promoted copper-ceria catalysts: “Bulk CuO CeO2 vs. CuO CeO2/Al2O3 with low mixed oxide content”

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