Surface and bulk properties of Cu–ZSM-5 and Cu/Al2O3 solids during redox treatments. Correlation with the selective reduction of nitric oxide by hydrocarbons

Praliaud, H.; Mikhailenko, Serguei D.; Chajar, Zakaria; Primet, Michel

doi:10.1016/s0926-3373(97)00093-3

Cited by 316 publications

(126 citation statements)

References 84 publications

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“…The large [3], as well as transitions characteristic of the copper-free zeolite H/SSZ-13. Between 550 and 1350 nm, another broad band is observed, which is characteristic of the copper sites, because it is not observed in the spectrum of H/SSZ-13 and has been assigned to the d-d transitions of isolated Cu 2+ [9][10][11][12] or copper hydroxyl species [13]. Bands in the range 350 and 650 nm are typically assigned to transitions in oxidic copper species, such as charge transfer transitions in O-Cu-O and Cu-O-Cu and Cu + in 3d clusters in CuO [3,12,14].…”

Section: Uv-vis Spectroscopy and H 2 -Tprmentioning

confidence: 99%

Ammonia Desorption Peaks Can Be Assigned to Different Copper Sites in Cu/SSZ-13

et al. 2017

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Section: Uv-vis Spectroscopy and H 2 -Tprmentioning

confidence: 99%

Ammonia Desorption Peaks Can Be Assigned to Different Copper Sites in Cu/SSZ-13

et al. 2017

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“…Eight coordinated tetravalent zirconium species are also responsible for the absorption in the range of 200-220 nm (Postole et al, 2010). The band at 550-1000 nm corresponds to the CuO phase, due to the Cu 2+ transition in octahedral oxygen configuration (Praliaud et al, 1998). After the cerium addition, the band at 270 nm is overlapped by the characteristic absorption of CeO 2 at 285 nm, assigned to O 2-→ Ce 4+ charge transfer transitions (Sinha and Suzuki, 2005), and this absorption strengthens with cerium content.…”

Section: Resultsmentioning

confidence: 99%

Influence of Ce/Zr Ratio on the Synergistic Effect over CuCe_1–xZr_xO_y/ZSM-5 Catalysts for the Self-Sustained Combustion of Carbon Monoxide

Zhao

Hao

Bin

et al. 2017

Combustion Science and Technology

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The self-sustained combustion of CO was studied over a series of CuCe 1-x Zr x O y /ZSM-5 catalysts with different Ce/Zr molar ratios to evaluate the correlation of their structural characteristics with catalytic performance. The obtained results demonstrated that the activity of the cerium-containing catalysts was much higher than that of the CuZr 1 /Z, with the activity of CO combustion following the order: CuZr 1 /Z < CuCe 0.25 Zr 0.75 /Z < CuCe 0.5 Zr 0.5 /Z < CuCe 1 /Z < CuCe 0.75 Zr 0.25 Z. After cerium addition, the cerium-zirconium mixed oxides formed promoted the copper species well dispersed on the catalyst surface. The high activities of cerium-containing catalysts were closely related to the synergetic effects among the copper, cerium, and zirconium species, as the surface copper species provided sites for CO adsorption and the cerium-zirconium mixed oxides promote the activation of oxygen. The activities were probably also attributed to some copper species present as substitutional defects in the ceria lattice, which were more reducible than the copper clusters, minicrystals, and bulk CuO particles. The CuCe 0.75 Zr 0.25 /Z possessed excellent redox capacity, adsorption/activation properties for O and CO species, and therefore induced a self-sustained combustion of CO at the lowest temperature than that of other CuCe 1-x Zr x O y /ZSM-5 catalysts.ARTICLE HISTORY

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“…As noticed in Figure 2, both copper loaded silica samples demonstrate comparable UV-vis spectra. The two bands spotted around 260 nm and 340-360 nm can be ascribed to charge transfer between mononuclear Cu 2+ ion and oxygen and between Cu 2+ and oxygen in oligonuclear [Cu-O-Cu] n surface species [34,35]. However, the broadness and the intensity of these two bands vary depending on the metal content, revealing a greater contribution of oligomeric copper oxide clusters in the case of the silica sample with the higher copper loading.…”

Section: Synthesis In Phosphate Buffer (Pb)mentioning

confidence: 97%

A Green Route to Copper Loaded Silica Nanoparticles Using Hyperbranched Poly(Ethylene Imine) as a Biomimetic Template: Application in Heterogeneous Catalysis

et al. 2017

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Abstract:Copper containing silica nanostructures are easily produced through a low cost versatile approach by means of hyperbranched polyethyleneimine (PEI), a water soluble dendritic polymer. This dendritic molecule enables the formation of hybrid organic/inorganic silica nanoparticles in buffered aqueous media, at room temperature and neutral pH, through a biomimetic silicification process. Furthermore, the derived hybrid organic/inorganic materials dispersed in water can be easily loaded with various copper amounts, due to the presence of PEI, which, despite having been integrated in the silica network, retains its strong copper chelating ability. Following calcination, the obtained copper loaded nanopowders are characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), N 2 adsorption, Temperature programmed reduction (TPR) and UV-Vis diffuse reflectance (UV-Vis-DR) techniques and evaluated for automotive exhaust purification under simulated conditions at the stoichiometric point. Effective control over final materials' pore structural and morphological characteristics is provided by employing different buffer solutions, i.e., tris(hydroxymethyl)aminomethane (Tris) or phosphate buffer. It was found that the enhancement of the nanopowders textural features, obtained in the presence of Tris buffer, had a great impact on the material's catalytic behavior, improving significantly its activity towards pollutants oxidation.

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Surface and bulk properties of Cu–ZSM-5 and Cu/Al2O3 solids during redox treatments. Correlation with the selective reduction of nitric oxide by hydrocarbons

Cited by 316 publications

References 84 publications

Ammonia Desorption Peaks Can Be Assigned to Different Copper Sites in Cu/SSZ-13

Ammonia Desorption Peaks Can Be Assigned to Different Copper Sites in Cu/SSZ-13

Influence of Ce/Zr Ratio on the Synergistic Effect over CuCe_1–xZr_xO_y/ZSM-5 Catalysts for the Self-Sustained Combustion of Carbon Monoxide

A Green Route to Copper Loaded Silica Nanoparticles Using Hyperbranched Poly(Ethylene Imine) as a Biomimetic Template: Application in Heterogeneous Catalysis

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Surface and bulk properties of Cu–ZSM-5 and Cu/Al2O3 solids during redox treatments. Correlation with the selective reduction of nitric oxide by hydrocarbons

Cited by 316 publications

References 84 publications

Ammonia Desorption Peaks Can Be Assigned to Different Copper Sites in Cu/SSZ-13

Ammonia Desorption Peaks Can Be Assigned to Different Copper Sites in Cu/SSZ-13

Influence of Ce/Zr Ratio on the Synergistic Effect over CuCe1–xZrxOy/ZSM-5 Catalysts for the Self-Sustained Combustion of Carbon Monoxide

A Green Route to Copper Loaded Silica Nanoparticles Using Hyperbranched Poly(Ethylene Imine) as a Biomimetic Template: Application in Heterogeneous Catalysis

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Influence of Ce/Zr Ratio on the Synergistic Effect over CuCe_1–xZr_xO_y/ZSM-5 Catalysts for the Self-Sustained Combustion of Carbon Monoxide