Preparation and characterization of Ce-Zr and Ce-Mn based oxides for n-hexane combustion: Application to catalytic membrane reactors

Picasso, Gino; Gutiérrez, M.; Pina, M.P.; Herguido, J.

doi:10.1016/j.cej.2006.09.005

Cited by 112 publications

(57 citation statements)

References 42 publications

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“…Enhanced reducibility of the mixed oxides is key in each of these applications and has indeed been inferred from temperature-programmed reduction (TPR) measurements [6,[16][17][18][19]. However, while TPR measurements can be used to quantify the reduction extent of a material, the characteristic temperature at which reduction occurs is only a qualitative measure of the ease with which a material reduces [20].…”

Section: Introductionmentioning

confidence: 99%

A Study of Cerium–Manganese Mixed Oxides for Oxidation Catalysis

2007

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Cerium-manganese mixed oxides with compositions of Ce 0.5 Mn 0.5 O 1.75 and Ce 0.8 Mn 0.2 O 1.9 were prepared by the citric-acid (Pechini) method and their catalytic properties were compared to CeO 2 and Mn 2 O 3 . The mixed oxides exhibited higher specific rates than either CeO 2 or Mn 2 O 3 for oxidation of both methane and n-butane. While XRD measurements of the mixed oxides suggested that the materials had primarily the fluorite structure, oxygen isotherms, measured by coulometric titration at 973 K, exhibited steps associated with MnO-Mn 3 O 4 and Mn 3 O 4 -Mn 2 O 3 equilibria, implying that manganese oxide must exist as separate phases in the solids. The P(O 2 ) for the MnO-Mn 3 O 4 equilibrium is shifted to lower values in the mixed oxides, indicating that the manganese-oxide phase is affected by interactions with ceria.

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Section: Introductionmentioning

confidence: 99%

A Study of Cerium–Manganese Mixed Oxides for Oxidation Catalysis

2007

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“…The combination and interaction between two metal elements significantly influence its bulk and surface physiochemical structure [15,16]. Ceria has been employed as a promoter for metal-containing ZSM-5 catalysts and its wide application is attributed to some special properties, such as: (1) the redox couple between the trivalent and tetravalent oxidation states of the ceria ions that allow easy oxygen exchange with the medium; (2) formation of labile oxygen vacancies and oxide ion storage; (3) to increase the dispersion and stability of the active form of the metal by strong metal-support interaction [17,18].…”

Section: Introductionmentioning

confidence: 99%

Cerium doped copper/ZSM-5 catalysts used for the selective catalytic reduction of nitrogen oxide with ammonia

Dou

Wang

et al. 2015

Chemical Engineering Journal

129

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Abstract:The CuCe/ZSM-5 catalysts with different cerium loadings (0, 0.5, 1.0, 1.5 and 2.0 wt.%) was investigated to evaluate the correlation between structural characteristics and catalytic performance for the selective catalytic reduction (SCR) of NO by NH3. It was found that the addition of cerium increased copper dispersion and prevented its crystallization. According to the results of X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction by hydrogen (H2-TPR), copper species were enriched on the ZSM-5 grain surfaces and part of copper ions was incorporated into the cerium lattice. Addition of cerium improved the redox properties of the CuCe/ZSM-5 catalysts, owing to the higher valence of copper and mobility of lattice oxygen than those of Cu/ZSM-5 catalyst. Hence the introduction of * Corresponding author. Tel.: +86-22-60601278; Fax.: +86-22-60600320 E-mail address: haoqinglan@tust.edu.cn ** Corresponding author. Tel.: +822 2220 0441; fax: +822 2220 2299 (K. Hui)E -mail address: kshui@hanyang.ac.kr (K. Hui) 2 cerium in Cu/ZSM-5 improved significantly NO conversion. On the one hand, the cerium introduction into Cu-Z enhances their low-temperature activities. 95% NO conversion is reached around 197 ºC for Cu-Z while the corresponding temperature value decreases to 148 ºC for CuCe4-Z. On the other hand, the temperature range of efficient NO reduction (95%) also extends to higher temperature when the cerium are added to Cu/ZSM-5. Among the Cu-Ce/ZSM-5 catalysts tested, the CuCe4-Z sample exhibits the highest catalytic activity with the temperature range for 90% NO removal of 148-427 ºC.

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“…Focusing on the Ce-rich composition (x up to 0.25) where manganese ions are incorporated into the ceria lattice forming a solid solution [8,27,28], it is evident that the addition of Mn ions leads to doubling of the TOF, but also to halving of the concentration of the active sites. At the same time, the SSA of Ce-rich mixed oxides is almost one order of magnitude higher than the one of pure CeO 2 , indicating that the presence of manganese ions is beneficial for the containment of crystal growth during catalyst synthesis and preservation of the nanostructure [8,28,29]. "Dilution" of manganese oxide with ceria, on the other hand, leads to a decrease of intrinsic activity by 50% as well as to a decrease of the concentration of active sites, but again to an increase of SSA.…”

Section: Discussionmentioning

confidence: 88%

Intrinsic Activity of MnOx-CeO2 Catalysts in Ethanol Oxidation

Delimaris

Ioannides

2017

Catalysts

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MnO x -CeO 2 mixed oxides are considered efficient oxidation catalysts superior to the corresponding single oxides. Although these oxides have been the subject of numerous studies, their fundamental performance indicators, such as turnover frequency (TOF) or specific activity, are scarcely reported. The purpose of the present work is to investigate the effect of catalyst composition on the concentration of active sites and intrinsic activity in ethanol oxidation by the employment of temperature-programmed desorption and oxidation of isotopically-labelled ethanol, 12 CH 3 13 CH 2 OH.The transformation pathways of preadsorbed ethanol in the absence of gaseous oxygen refer to dehydrogenation to acetaldehyde followed by its dissociation combined with oxidation by lattice oxygen. In the presence of gaseous oxygen, lattice oxygen is rapidly restored and the main products are acetaldehyde, CO 2 , and water. CO 2 forms less easily on mixed oxides than on pure MnO x . The TOF of ethanol oxidation has been calculated assuming that the amount of adsorbed ethanol and CO 2 produced during temperature-programmed oxidation (TPO) is a reliable indicator of the concentration of the active sites.

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Preparation and characterization of Ce-Zr and Ce-Mn based oxides for n-hexane combustion: Application to catalytic membrane reactors

Cited by 112 publications

References 42 publications

A Study of Cerium–Manganese Mixed Oxides for Oxidation Catalysis

A Study of Cerium–Manganese Mixed Oxides for Oxidation Catalysis

Cerium doped copper/ZSM-5 catalysts used for the selective catalytic reduction of nitrogen oxide with ammonia

Intrinsic Activity of MnOx-CeO2 Catalysts in Ethanol Oxidation

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