Synthesis and Characterization of Stable and Crystalline Ce1-xZrxO2 Nanoparticle Sols

Deshpande, Atul Suresh; Pinna, Nicola; Beato, Pablo; Antonietti, Markus; Niederberger, Markus

doi:10.1021/cm040155w

Cited by 121 publications

(90 citation statements)

References 41 publications

(71 reference statements)

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“…CuO/ZrO 2 /CeO 2 (CZC) catalysts were investigated in one of our previous kinetic studies. Preparation and characterization of these materials is given in detail in the literature [5,29]. The CZC15 sample containing about 15 mol-% CuO was showing the best selectivity for SRM against CO formation and was therefore chosen for this study.…”

Section: Catalysts Samplesmentioning

confidence: 99%

Steam reforming of methanol over copper-containing catalysts: Influence of support material on microkinetics

Frank

Jentoft

Soerijanto

et al. 2007

Journal of Catalysis

181

135

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Steam reforming of methanol (SRM) was investigated over copper-containing catalysts supported on four different oxides and mixed oxides: Cu/ZnO/Al 2 O 3 , Cu/ZrO 2 /CeO 2 , Cu/SiO 2 and Cu/Cr 2 O 3 /Fe 2 O 3 . After observing slight differences in the way of catalyst aging and experimental exclusion of mass transport limitation effects, a detailed kinetic study was carried out at 493 K. The dependence of the reaction rate on the molar ratio of methanol and water was determined as well as the influence of addition of inert nitrogen and the main reaction products hydrogen and carbon dioxide to the reactant mixture. Although there were remarkable differences in the catalytic activity of the samples, the main mechanistic steps reflected in the rate law appeared to be similar for all catalysts. The reaction rate is mainly determined by the methanol partial pressure, whereas water is not involved in the rate determining step, except over Cu/Cr 2 O 3 /Fe 2 O 3 , where several differences in the chemistry were observed. Hydrogen and carbon dioxide were found to inhibit the reaction. These results were confirmed by a DRIFTS study at 493 K using an equimolar reactant mixture and an excess of 4:1 of water and methanol, respectively. The same surface species could be identified on each catalyst but neither kinetic modelling nor the DRIFTS spectra could give a clear answer if the reaction pathway occurs via a dioxomethylene or a methyl formate species as intermediate. Similar activation energies of SRM confirm the assumption, that the surface chemistry of SRM over copper-based systems is independent of the catalyst support material.

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Section: Catalysts Samplesmentioning

confidence: 99%

Steam reforming of methanol over copper-containing catalysts: Influence of support material on microkinetics

Frank

Jentoft

Soerijanto

et al. 2007

Journal of Catalysis

181

135

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“…Depending on the sample composition, the HNO 3 :metal molar ratio was varied between 1:1 and 1.5:1. Ultrasonic treatment of the suspension for 45-60 min resulted in the formation of a transparent sol [35]. Templating was carried out by using XAD-16 nonfunctionalized polystyrene beads (a Sigma product), with a specific surface area of 800 m 2 g -1 and an average pore diameter of 10 nm.…”

Section: 1catalyst Preparationmentioning

confidence: 99%

Steam reforming of methanol over Cu/ZrO/CeO catalysts: a kinetic study

Mastalir

Frank

Szizybalski

et al. 2005

Journal of Catalysis

135

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Steam reforming of methanol (SRM) was investigated over Cu/ZrO 2 /CeO 2 (CZC) catalysts prepared via a novel synthetic method based on coprecipitation and polymer templating. Structural characterization of the samples was performed by N 2 adsorption-desorption, N 2 O decomposition, and X-ray diffraction. The variation of the Cu loading resulted in an increased Cu crystallite size and a decreased specific surface area of the active particles. Catalytic investigations were carried out in a fixed bed reactor at 10 5 Pa, by applying a CH 3 OH:H 2 O = 1:1 ratio. The samples with Cu contents higher than 5 % exhibited good long-term stabilities and low CO levels during continuous operation. The kinetic model suggested for the transformation involved the reverse water-gas shift (RWGS) and methanol decomposition (MD), in addition to the SRM reaction. Kinetic measurements were accomplished in the temperature range 503-573 K and the experimental results could be well simulated. The highest methanol conversions and the lowest CO levels were observed in the temperature range 523-543 K. The apparent activation energies for the individual reactions were found to depend on the Cu content of the catalyst. Since the influence of mass transport limitations on the kinetic data could be excluded, it was established that the variation of the Cu concentration in the precursor material altered the microstructure of the Cu particles and, accordingly, the active Cu surface, which resulted in the formation of significantly different catalysts.Keywords: steam reforming of methanol, copper, zirconia, ceria, N 2 O chemisorption, long term stability, CO formation, kinetic model, reverse water-gas shift reaction, methanol decomposition, activation energy 1.IntroductionIn the past decade, considerable attention has been focused on the reduction of the significant emissions originating from mobile sources, such as internal combustion engines [1][2][3][4]. For environmental reasons, the development of proton-exchange membrane fuel cells (PEMFCs) has gained in increasing importance [5,6]. As compared with conventional heat engines, several advantages of fuel cell application have been established, including a higher efficiency and a more convenient operation, the absence of moving parts and the low emission of hazardous compounds [1,5]. The combustion of hydrogen in a fuel cell is regarded as a clean process, releasing energy and providing only water as an exhaust material [4,7,8]. However, hydrogen is not a natural energy source and must be generated by consuming a large amount of energy, either from natural gas or via the electrolysis of water [4]. Furthermore, for a fuel cell vehicle, the storage and the supply of hydrogen, a volatile and explosive gas, imposes mechanical problems and safety hazards on a commercial level [1,4,8].Several liquid fuel candidates have been discussed for on-board reforming, including methanol, ethanol, gasoline and diesel [1], of which methanol is considered the most favourable alternative [1,9]. Although mo...

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“…For example, Li et al prepared nanocrystalline Ce IV 1Àx Y III x O 2Àx/2 (x 0.35) by coprecipitation. [8] Deshpande et al also used coprecipitation to form nanoparticles of ceria-zirconia (Ce IV 1Àx Zr IV x O 2 ) with a small particle size distribution, [9] and Inomata and co-workers used hydrothermal synthesis to dope Fe III ions into nanoscale ceria. [10] Hydrothermal synthesis is perhaps best known for its use in the preparation of zeolites and other nanoporous solids.…”

Section: Oxides Containing Cementioning

confidence: 99%

“…Powder X-ray diffraction (XRD) reveals that (Na 1/3 -Ce 2/3 ) 2 Ti 2 O 7 crystallizes in the space group Fd3 m with a = 10.120 (9) and is isostructural with the cubic pyrochlore Y 2 Ti 2 O 7 .…”

Section: Oxides Containing Cementioning

confidence: 99%

Hydrothermal Synthesis of a Cerium(IV) Pyrochlore with Low‐Temperature Redox Properties

et al. 2006

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Synthesis and Characterization of Stable and Crystalline Ce_1-xZr_xO₂ Nanoparticle Sols

Cited by 121 publications

References 41 publications

Steam reforming of methanol over copper-containing catalysts: Influence of support material on microkinetics

Steam reforming of methanol over copper-containing catalysts: Influence of support material on microkinetics

Steam reforming of methanol over Cu/ZrO/CeO catalysts: a kinetic study

Hydrothermal Synthesis of a Cerium(IV) Pyrochlore with Low‐Temperature Redox Properties

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