Reply to the comment submitted by L.F.C. de Oliveira, F.R.L. Faulstich, F.M.Z. Zotin on “Raman spectroscopy and X-ray diffraction study of the phase transformation of ZrO2–Al2O3 and CeO2–Al2O3 nanocomposites” by S. Boullosa-Eiras, E. Vanhaecke, T. Zhao, D. Chen, A. Holmen [Catal. Today, 166 (2011) 10–17]

Boullosa-Eiras, Sara; Vanhaecke, Estelle; Zhao, Tiejun; Chen, De; Holmén, Anders

doi:10.1016/j.cattod.2012.03.002

Cited by 12 publications

(19 citation statements)

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“…Thus, there is a great interest in designing catalysts that minimize the deleterious effect of coking. The presence of oxygen vacancies in supports that contain CeO 2 proved to be instrumental in keeping the metal particles free from coke deposition during the steam reforming, [3][4][5] partial oxidation, 6-9 CO 2 reforming and autothermal reforming of methane, [10][11][12] when using nickel or noble metals as catalysts. [13][14][15] Furthermore, ceria may also improve the catalytic performance by increasing the noble metal dispersion and stabilizing the support.…”

Section: Introductionmentioning

confidence: 99%

“…6,10 An increase in the activity of Rh/CeZrO 2, for the partial oxidation of methane as a result of a higher Rh dispersion has also been reported. 11,12 In this work, the effects of the support on the partial oxidation of methane were investigated further. Rh/g-Al 2 O 3 , Rh/CeO 2 , Rh/ZrO 2 and Rh/Ce-ZrO 2 catalysts were prepared and characterized by diffuse reflectance UV-Vis spectroscopy (DR-UV-Vis spectroscopy), temperature programmed reduction (TPR), X-ray diffractometry (XRD), CO and H 2 chemisorption and diffuse reflectance infrared spectroscopy (DRIFTS) of adsorbed CO.…”

Section: Introductionmentioning

confidence: 99%

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Partial oxidation of methane to syngas on Rh/Al2O3 and Rh/Ce-ZrO2 catalysts

Oliveira¹,

Bitencourt²,

Passos³

2013

J. Braz. Chem. Soc.

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A oxidação parcial do metano sobre catalisadores de ródio suportados em g-Al 2 O 3 , CeO 2 , ZrO 2 e Ce-ZrO 2 foi investigada. Medidas de DRIFTS (espectroscopia no infravermelho com reflectância difusa) de CO adsorvido mostraram que houve a formação de diferentes espécies de ródio nos diferentes suportes, o que por sua vez influenciou na dispersão do metal. Os efeitos da dispersão metálica e da capacidade de armazenamento de oxigênio sobre a atividade dos catalisadores na oxidação parcial foram discutidos.The partial oxidation of methane with g-Al 2 O 3 -, CeO 2 -, ZrO 2 -and Ce-ZrO 2 -supported rhodium catalysts was investigated. DRIFTS (diffuse reflectance infrared spectroscopy) measurements of adsorbed CO showed the formation of different rhodium species on different supports, which influenced the dispersion of the metal. The effects of the metal dispersion, oxygen storage capacity on the activity of these catalysts for the partial oxidation of methane are discussed.Keywords: methane partial oxidation, methane, ceria-zirconia, rhodium, DRIFTS IntroductionThe catalytic partial oxidation of methane is an alternative to steam reforming, the industrial process for the production of synthesis gas from methane. Partial oxidation is a more energy efficient and less expensive process than steam reforming. The partial oxidation of methane (POM) is a mildly exothermic reaction, in which methane reacts with a limited amount of oxygen to produce hydrogen and carbon monoxide:The POM process is capable of producing syngas with a H 2 /CO ratio of approximately 2, which makes it a favorable method for methanol and hydrocarbon synthesis. 1,2 Noble metal catalysts (Ir, Ru, Rh, Pt, Pd) exhibit high activity, along with long-term stability, while minimizing the levels of coking, particularly when compared to the non-noble metals (such as Fe, Co, Ni). 1,2 The lack of a hydrogen infrastructure, as well as disadvantages in hydrogen storage, has stimulated the development of compact fuel processors, which are able to produce a rich hydrogen gas mixture from hydrocarbons. Several studies have reported that Rh catalysts are especially appropriate for use in compact fuel processors because of their high activity, selectivity for syngas and resistance to carbon deposition. 2 One of the main disadvantages of methane conversion is the deactivation due to coke formation. Thus, there is a great interest in designing catalysts that minimize the deleterious effect of coking. The presence of oxygen vacancies in supports that contain CeO 2 proved to be instrumental in keeping the metal particles free from coke deposition during the steam reforming, 3-5 partial oxidation, 6-9 CO 2 reforming and autothermal reforming of methane, 10-12 when using nickel or noble metals as catalysts. [13][14][15] Furthermore, ceria may also improve the catalytic performance by increasing the noble metal dispersion and stabilizing the support. Both the metal dispersion and support reducibility of Pt/CeO 2 and Pt/Ce x Zr 1-x O 2 were found to influence the catalytic ...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Partial oxidation of methane to syngas on Rh/Al2O3 and Rh/Ce-ZrO2 catalysts

Oliveira¹,

Bitencourt²,

Passos³

2013

J. Braz. Chem. Soc.

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“…Particles deposited on aluminium exhibit two main bands of Fe 2 O 3 at 211 and 270 cm -1 , whereas stainless steel and titanium have approximately the same bands at 215 and 278 cm -1 , followed by Cu x O y /Cu foil and finally graphite foil at 224 and 290 cm -1 . This shift to higher Raman wave numbers can be explained by the different particle sizes [48][49][50] on the foils with the following evolution to the particle size: aluminium \ stainless steel, titanium \ Cu x O y /Cu \ graphite. Figure 3 shows SEM images of the foils after catalyst deposition at 750°C.…”

Section: In Situ Deposition Of Fe Catalysts By Ferrocene Decompositionmentioning

confidence: 94%

Catalytic Consequence of the Interface Between Iron Catalysts and Foils in Synthesis of Aligned Nanocarbons on Foils

Vanhaecke

Huang

et al. 2011

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Growth of aligned carbon nanotubes on different substrates such as titanium, copper, stainless steel and graphite foils has been investigated by different characterization techniques such as SEM, TEM, contact angle measurements and Raman spectroscopy. The study aims at gaining a better understanding of the effects of the surface properties of the foils on the alignment, diameter distribution, structure and the yield of nanocarbons. The results revealed that the surface tension of the foils has a significant influence on the size of the Fe catalyst particles on the foil surfaces obtained by ferrocene decomposition. The size of the Fe particles directly determined the structure and alignment of the nanocarbons on the foils. Small sized (about 10 nm) and highly crystalline carbon nanotubes were produced on foils such as Al and Ti with the low surface tension, while it is hard to grow any nanocarbon on the Cu foils due to too high surface tension. Lowering the surface tension of the Cu foils by surface oxidation made it possible to grow carbon nanofibers.

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“…A similar procedure is carried out to prepare the multi-component complex solution, 5 wt% Zr x Ce 1-x O 2 /Al 2 O 3 (x = 0, 0.25, 0.5, 0.75.1), using ZrO(NO 3 ) 2 ÁxH 2 O, Ce(NO 3 ) 3 Á6H 2 O, CA (C 6 H 8 O 7 ). More details can be found elsewhere [27,33]. Nanocomposites are produced after these dried solids are calcined in air at 1,173 K for 5 h or 1,373 K for 24 h.…”

Section: Al 2 O 3 Based Nanocompositesmentioning

confidence: 99%

“…Recently, a series of Zr x Ce 1-x O 2 /Al 2 O 3 nanocomposites have been prepared by impregnation of these metal-CA-PEG complexes. High thermal stability of these composites is illustrated by X-ray diffraction (XRD) and Raman spectroscopy, and an oxide-coated nanostructure of these composites is found by combining visible and UV Raman spectroscopy [27].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Supported Catalysts by Impregnation and Calcination of Low-Temperature Polymerizable Metal-Complexes

Zhao

Boullosa-Eiras

et al. 2011

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The low-temperature polymerizable metal complex solution has been used as an active component precursor to prepare supported (structured) catalysts by a straight-forward sequence of impregnation, drying and calcination. Two typical samples, 5 wt% Zr x Ce 1-x O 2 / Al 2 O 3 nanocomposite and structured carbon nanofiber supported Cu-CeO 2 catalyst, are prepared to explore the potential of this method in the controlled synthesis of catalysts and catalyst supports. The interaction between the active component precursor and the surface of the solid matrices during impregnation and drying is investigated by infrared spectroscopy (IR) and transmission electron microscopy (TEM), demonstrating that the in situ polymerization process is crucial for the deposition of the active component on the surface of solid matrices. The evolution of the phase transformation and the structure of the produced materials during the calcination step is studied by coupling thermal gravimetric analysis-differential thermal analysis-mass spectroscopy (TGA-DTA-MS), TEM and X-ray diffraction (XRD) measurements, indicating that higher thermal stable particles or smaller particles can be obtained with the presence of the Al 2 O 3 or structured carbon nanofibers (SCNF), respectively, after calcination. This method combines the advantages of sol-gel and impregnation, representing a promising route for preparing supported catalysts and catalyst supports. The limitations of the method are also discussed.

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Cited by 12 publications

References 1 publication

Partial oxidation of methane to syngas on Rh/Al2O3 and Rh/Ce-ZrO2 catalysts

Partial oxidation of methane to syngas on Rh/Al2O3 and Rh/Ce-ZrO2 catalysts

Catalytic Consequence of the Interface Between Iron Catalysts and Foils in Synthesis of Aligned Nanocarbons on Foils

Synthesis of Supported Catalysts by Impregnation and Calcination of Low-Temperature Polymerizable Metal-Complexes

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