Characterization of copper-silica catalysts prepared by ion exchange

Shimokawabe, Masahide; Takezawa, Nobutsune; Kobayashi, Haruo

doi:10.1016/0166-9834(82)80156-5

Cited by 62 publications

(43 citation statements)

References 10 publications

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“…In fact, Gang et al [42] see this band clearly in unsupported CuO. The adsorption edge characteristic of bulk CuO particles is also clearly seen at wavelengths longer than 750-800 nm [44]. Therefore, the UV-vis DRS spectra are in perfect agreement with what is seen in the XRD and the TPR observations, which show the formation of bulk CuO in these catalysts regardless of the calcination temperature.…”

Section: Characterization Of the Catalystssupporting

confidence: 71%

THERMAL STABILITY OF THE Cu-CeO2 INTERFACE ON SILICA AND ALUMINA, AND ITS RELATION WITH ACTIVITY IN THE OXIDATION REACTION OF CO AND THE DECOMPOSITION OF N2O

Alvarez

Águila

Guerrero

et al. 2018

J. Chil. Chem. Soc.

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The effect of the support on the formation of the Cu-CeO 2 interface and its thermal stability after calcination at 500, 700 and 900 ºC is studied. The supports used are SiO 2 , because of its inert character, and Al 2 O 3 , because it can interact with the Cu and Ce species on the surface. The catalysts were characterized by BET, XRD, UV-vis DRS, and TPR with H 2 . The catalytic activity in the CO oxidation reactions with O 2 at low temperature and the decomposition of N 2 O were selected to visualize the effect of temperature on the concentration of Cu-CeO 2 interfacial sites. The results show that at a calcination temperature of 500 ºC the formation of the Cu-CeO 2 interface is favored over the SiO 2 support. However, the stability of the Cu-CeO 2 interface on SiO 2 is much lower than on Al 2 O 3 , causing a substantial decrease of the interfacial sites calcining at 700 ºC, and segregation of the Cu and Ce species on the surface of the silica, with complete loss of the catalytic activity in both reactions when calcining at 900 ºC. In contrast, on alumina the Cu-CeO 2 interface is more stable and presents a significant catalytic activity in both reactions, even when calcining at 900 ºC. The characterization results show that the sintering process of Cu species and CeO 2 particles is less on the alumina support due to the greater interaction of the Cu and Ce with this support.

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Section: Characterization Of the Catalystssupporting

confidence: 71%

THERMAL STABILITY OF THE Cu-CeO2 INTERFACE ON SILICA AND ALUMINA, AND ITS RELATION WITH ACTIVITY IN THE OXIDATION REACTION OF CO AND THE DECOMPOSITION OF N2O

Alvarez

Águila

Guerrero

et al. 2018

J. Chil. Chem. Soc.

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“…Multiple bands are observed in the 200-300 nm region, corresponding to O 2À to Cu 2 + CT of isolated copper oxide species. [31][32][33] The presence of such CuO species on both components (as shown by EDX) of the catalyst accounts for the multiple observed features. The position of these CT bands is known to depend on the type and morphology of the supports and the procedure employed to support CuO.…”

Section: Samplementioning

confidence: 88%

“…[37] The 260 nm band was assigned to an LMCT of isolated octahedral Cu 2 + ÀO 2À species, whereas the latter band was attributed to the presence of oligomers of the type CuÀ OÀCu. Derrien and co-workers [38] reported a band at 235 nm for CuO supported on mesoporous SiO 2 spheres, whereas Shimokawabe et al [32] reported the same band to be at 270 nm for CuO supported on SiO 2 , which illustrates the additional dependence on morphology.…”

Section: Samplementioning

confidence: 94%

Effect of Preparation Method and CuO Promotion in the Conversion of Ethanol into 1,3‐Butadiene over SiO₂–MgO Catalysts

et al. 2014

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Silica-magnesia (Si/Mg=1:1) catalysts were studied in the one-pot conversion of ethanol to butadiene. The catalyst synthesis method was found to greatly influence morphology and performance, with materials prepared through wet-kneading performing best both in terms of ethanol conversion and butadiene yield. Detailed characterization of the catalysts synthesized through co-precipitation or wet-kneading allowed correlation of activity and selectivity with morphology, textural properties, crystallinity, and acidity/basicity. The higher yields achieved with the wet-kneaded catalysts were attributed to a morphology consisting of SiO2 spheres embedded in a thin layer of MgO. The particle size of the SiO2 catalysts also influenced performance, with catalysts with smaller SiO2 spheres showing higher activity. Temperature-programmed desorption (TPD) measurements showed that best butadiene yields were obtained with SiO2-MgO catalysts characterized by an intermediate amount of acidic and basic sites. A Hammett indicator study showed the catalysts' pK(a) value to be inversely correlated with the amount of dehydration by-products formed. Butadiene yields could be further improved by the addition of 1 wt% of CuO as promoter to give butadiene yields and selectivities as high as 40% and 53%, respectively. The copper promoter boosts the production of the acetaldehyde intermediate changing the rate-determining step of the process. TEM-energy-dispersive X-ray (EDX) analyses showed CuO to be present on both the SiO2 and MgO components. UV/Vis spectra of promoted catalysts in turn pointed at the presence of cluster-like CuO species, which are proposed to be responsible for the increased butadiene production.

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“…3 Several authors have reported studies of sol-gel prepared SiO 2 samples containing copper. According to our results, the copper silicate formed is probably the dioptase, which is a metasilicate with the chemical formula Cu 6 [Si 6 O 18 ] и 6H 2 O. [9][10][11] In the present work, we prepared sol-gel SiO 2 glasses containing copper, and the structural evolutions, due to heat treatments in air, have been analyzed using Raman spectroscopy, infrared (IR) absorption, and x-ray diffraction.…”

Section: Introductionmentioning

confidence: 98%

Formation of silicate structures in Cu-containing silica xerogels

2000

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Using infrared absorption and Raman spectroscopy, the structure of SiO 2 sol-gel samples containing copper were analyzed as a function of air heat treatments. The weight composition of the samples was 70(SiO 2 )-30(CuO) and the thermal treatments were carried out in air at various temperatures in the range of 100-600°C. It was found that the Cu might be incorporated into the SiO 2 matrix at least in two ways: forming oxide particles and forming metasilicatelike structures. The copper metasilicate found had the chemical formula, Cu 6 [Si 6 O 18 ] и 6H 2 O, which is known as dioptase with a thermal stability at temperatures up to 600°C.

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Characterization of copper-silica catalysts prepared by ion exchange

Cited by 62 publications

References 10 publications

THERMAL STABILITY OF THE Cu-CeO2 INTERFACE ON SILICA AND ALUMINA, AND ITS RELATION WITH ACTIVITY IN THE OXIDATION REACTION OF CO AND THE DECOMPOSITION OF N2O

THERMAL STABILITY OF THE Cu-CeO2 INTERFACE ON SILICA AND ALUMINA, AND ITS RELATION WITH ACTIVITY IN THE OXIDATION REACTION OF CO AND THE DECOMPOSITION OF N2O

Effect of Preparation Method and CuO Promotion in the Conversion of Ethanol into 1,3‐Butadiene over SiO₂–MgO Catalysts

Formation of silicate structures in Cu-containing silica xerogels

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Characterization of copper-silica catalysts prepared by ion exchange

Cited by 62 publications

References 10 publications

THERMAL STABILITY OF THE Cu-CeO2 INTERFACE ON SILICA AND ALUMINA, AND ITS RELATION WITH ACTIVITY IN THE OXIDATION REACTION OF CO AND THE DECOMPOSITION OF N2O

THERMAL STABILITY OF THE Cu-CeO2 INTERFACE ON SILICA AND ALUMINA, AND ITS RELATION WITH ACTIVITY IN THE OXIDATION REACTION OF CO AND THE DECOMPOSITION OF N2O

Effect of Preparation Method and CuO Promotion in the Conversion of Ethanol into 1,3‐Butadiene over SiO2–MgO Catalysts

Formation of silicate structures in Cu-containing silica xerogels

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Effect of Preparation Method and CuO Promotion in the Conversion of Ethanol into 1,3‐Butadiene over SiO₂–MgO Catalysts