CuI-Y and CuII-Y zeolites: a XANES, EXAFS and visible-NIR study

Lamberti, Carlo; Spoto, G.; Scarano, Domenica; Pazé, C.; Salvalaggio, Mario; Bordiga, Silvia; Zecchina, Adriano; Palomino, Gemma Turnes; d’Acapito, Francesco

doi:10.1016/s0009-2614(97)00297-2

Cited by 82 publications

(74 citation statements)

References 33 publications

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“…Recent studies by Fowkes et al (2002) have shown that, upon reduction of Cu(II)-Y, there was a redistribution of cation positions and most of the reduced species (Cu ϩ ) occupied sites I* and II. Lamberti et al (1997) showed similar results for both reduced Cu(II)-Y and Cu(I)-Y prepared, respectively, by ion exchange and gas-phase reaction with CuCl vapor. In addition, some Cu ϩ ions could be induced to migrate to more exposed sites in the presence of guest molecules.…”

Section: Adsorbent Activation Copper Autoreduction and Migrationsupporting

confidence: 54%

New sorbents for desulfurization of diesel fuels via π‐complexation

2004

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Desulfurization of a commercial diesel fuel by different adsorbents was studied in a fixed-bed adsorber operated at ambient temperature and pressure. In general, the adsorbents tested for total sulfur adsorption capacity at breakthrough followed the order: AC/Cu(I)-Y Ͼ Cu(I)-Y Ͼ Selexsorb CDX (alumina) Ͼ CuCl/␥-Al 2 O 3 Ͼ activated carbon Ͼ Cu(I)-ZSM-5. The best adsorbent, AC/Cu(I)-Y (layered bed of 15 wt % activated carbon followed by Cu(I)Y), is capable of producing 30 cm 3 of diesel fuel per gram of adsorbent with a weighted average content of 0.15 ppmw-S, and about 20 cm 3 of diesel fuel per gram of adsorbent with a weighted average content of 0.06 ppmw-S. These low-sulfur fuels are suitable for fuel cell applications. The added layer of carbon not only delayed the sulfur breakthrough significantly but also sharpened the sulfur wavefronts. GC-FPD results showed that the -complexation sorbents selectively adsorbed highly substituted thiophenes, benzothiophenes, and dibenzothiophenes from diesel, which is not possible with conventional hydrodesulfurization (HDS) reactors. The high sulfur selectivity and high sulfur capacity of Cu(I)Y were because of -complexation. © 2004 AmericanInstitute of Chemical Engineers AIChE J, 50: [791][792][793][794][795][796][797][798][799][800][801] 2004 Keywords: desulfurization of liquid fuels, -complexation sorbent, desulfurization by adsorption, desulfurization of diesel, 4-methyl-dibenzothiophene adsorption, 4, 6-dimethyl- dibenzothiophene adsorption IntroductionThe federal government mandates a reduction in gasoline and diesel sulfur levels to 30 and 15 ppm, respectively, from the current levels of 300 -500 ppmw, to be implemented by 2006(Krause, 2000. This makes refiners consider eliminating production of onboard transportation fuels because of the high costs that will arise from compliance with such regulations (Parkinson, 2001). For fuel cell applications with gasoline as the feed, the sulfur content should be below 1 ppmw. For automotive fuel cells, liquid hydrocarbons are ideal fuels because of their higher energy density, availability, and safety for transportation and storage. However, the water-gas shift catalysts as well as fuel-cell electrode catalysts are poisoned by sulfur, and the sulfur content in the liquid fuel needs to be preferably less than 0.1 ppmw.Hydrodesulfurization (HDS) is very effective in removing thiols and sulfides, but it is not effective for the removal of thiophenic compounds. For example, the H 2 S produced during reaction of some thiophene derivatives is one of the main inhibitors for deep HDS of unreactive species (Ma et al., 1994;Knudsen et al., 1999). Among the unreacted refractory species are 4-methyl-dibenzothiophene (4-MDBT) and 4,6-dimethyldibenzothiophene (4, 6-DMDBT). These molecules are common in diesel fuels. The methyl groups in these species create a steric effect that hinders the capacity of HDS catalysts to chemisorb the sulfur atoms as depicted in Figure 1a. Such steric hindrance is not present for adsorption by -complexatio...

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Section: Adsorbent Activation Copper Autoreduction and Migrationsupporting

confidence: 54%

New sorbents for desulfurization of diesel fuels via π‐complexation

2004

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“…64 The peak at 1.5 Å in the FT of k 3 -weighted Cu K-edge EXAFS was assignable to a Cu-O moiety. 65 The results of the curve-fitting analysis are summarized in Table 6 and the pores of zeolite-X. 68 …”

Section: Preparation and Characterization Of Montmorillonite-enwrappementioning

confidence: 99%

Design of High-Performance Heterogeneous Metal Catalysts for Green and Sustainable Chemistry

Kaneda¹,

Ebitani²,

Mizugaki³

et al. 2006

Bulletin of the Chemical Society of Japan

143

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This account reviews a novel approach to designing high-performance heterogeneous metal catalysts using hydroxyapatites, montmorillonites, and hydrotalcites as macroligands of active metal species for aerobic alcohol oxidations, carbon-carbon bond formations, and one-pot syntheses. The catalytic systems using the above heterogeneous catalysts offer significant benefits in achieving environmentally friendly organic syntheses aiming towards Green and Sustainable Chemistry. Furthermore, the present preparation method for the immobilization of metal species is strikingly simple and allows a strong protocol for creating various nanostructured and functionalized heterogeneous catalysts.Green and Sustainable Chemistry (GSC) is a revolutionary philosophy that aims to bring about a sustainable society by improvement of the safety and environmental aspects of chemical processes and reduction of the risks of chemical products to people and the environment.1 The emphasis is on eliminating waste at the source-primary pollution prevention-rather than finding incremental end-of-pipe solutions. This concept aims to solve the societal problems of the last century associated with the mass production and consumption of materials, and plays a prime role in providing a venous function in society, encouraging reuse and circulation of resources.One of the powerful solutions in the move toward GSC is the replacement of traditional synthetic methods using harmful stoichiometric reagents that produce vast amounts of waste with cleaner and simple catalytic alternatives with high atom efficiency 1a and low E-factors. 1b Catalytic chemistry, therefore, is of ever-increasing importance because catalysis is a key element in material transformations at atomic and molecular levels, which are an essential realm of chemistry and chemical processes.Our approach to GSC is to develop a highly functionalized heterogeneous metal catalyst based on the unique characteristics of natural layered inorganic materials such as hydroxyapatite, montmorillonite, and hydrotalcite, by using them as macroligands for metal species.2 We consider the above inorganic materials to be advanced nano-scaled catalyst supports allowing for the control of the location of catalytically active metal species, which can be found, for example, on the surface, among the layers, or in the interlayer space. Furthermore, these materials are capable of creating catalytically active metal species responsible for targeted organic transformations involving monomers, chain-like species or giant clusters. The creation of well-defined active metal sites on a solid surface, as characterized by X-ray absorption spectroscopy, not only opens up an avenue to materials that boost catalytic performance, but also aids in the understanding of the molecular basis of heterogeneous catalysis. Another advantage of these catalysts is the possibility of a one-pot synthesis based on a cooperative action by several immobilized active species on the solid surface as multifunctional catalysts. The target react...

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“…[79,80] Determination of the Cu oxidation state, coordination number and CuϪO bond lengths can be achieved by X-ray absorption fine structure (XAFS) techniques. [81,82] However, for isolated Cu II sites the EXAFS (extended X-ray absorption fine structure) spectrum only yields average CuϪO bond lengths and coordination numbers. Hence, this technique is not well suited to offer detailed information on the different Cu II sites and is more often used to distinguish between isolated versus clustered Cu ions in over-exchanged zeolites.…”

Section: Additional Observationsmentioning

confidence: 99%

The Coordination of CuII in Zeolites − Structure and Spectroscopic Properties

Delabie

Pierloot

Groothaert

et al. 2002

Eur. J. Inorg. Chem.

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Keywords: Zeolites / Copper / Ab initio calculations / Density functional calculations / ESR spectroscopy / UV/Vis spectroscopy / Heterogeneous catalysis Zeolites loaded with transition metal ions are promising heterogeneous catalysts. Knowledge about the location and structure of the metal centers is of paramount importance for the understanding of the catalytic potential of these materials. In this work, the spectroscopic studies of the coordination of Cu II in zeolite A, ZK4, X, Y and mordenite are reviewed. Experimentally, diffuse reflectance spectroscopy [a] teaches general chemistry and computational chemistry. Her main research interest is the application of ab initio methods for the study of spectroscopic and magnetic properties of systems containing transition metals. Marijke H. Groothaert (left center) was born in Neerpelt, Belgium in 1975. In 1998 she received her M. S. degree from the . Since 1998 she is a PhD student at the Center for Surface Chemistry and Catalysis under the supervision of Professor Robert A. Schoonheydt. Her research is concentrated on the coordination of transition metal ions in zeolites and combines spectroscopic techniques with computational methods. Robert A. Schoonheydt (left bottom) received his M. S. degree in 1966 and . Hab. in Leuven, where he teaches quantum chemistry, computational chemistry, and inorganic chemistry. His main research interests are in the application of computational methods in different areas of chemistry.MICROREVIEWS: This feature introduces the readers to the authors' research through a concise overview of the selected topic. Reference to important work from others in the field is included. 515(DRS) and electron spin resonance (ESR) spectroscopy have been applied to study the coordination of Cu II in zeolites. Ab initio calculations on model clusters, representing the Cu II sites in zeolites, are used for the interpretation of the experimental data. The combination of experimental spectroscopic information with theoretical results leads to a new and profound insight into the Cu II −zeolite interaction.

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CuI-Y and CuII-Y zeolites: a XANES, EXAFS and visible-NIR study

Cited by 82 publications

References 33 publications

New sorbents for desulfurization of diesel fuels via π‐complexation

New sorbents for desulfurization of diesel fuels via π‐complexation

Design of High-Performance Heterogeneous Metal Catalysts for Green and Sustainable Chemistry

The Coordination of CuII in Zeolites − Structure and Spectroscopic Properties

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