Supported Vanadium Oxide Catalysts: Quantitative Spectroscopy, Preferential Adsorption of V^4+/5+, and Al2O3 Coating of Zeolite Y

A series of supported vanadium oxide catalysts were prepared by the incipient wetness method as a function of the support composition (Al2O3, SiO2, and USY), the metal oxide loading (0-1 wt %), and the impregnation salt (vanadyl sulfate and ammonium vanadate). These catalysts have been studied by combined DRS-ESR spectroscopies in order to quantify the amount of V^4+ and V^5+ and to unravel their coordination geometries. These spectroscopic fingerprints have been used to study the preferential adsorption of V^4+/5+ ions on SiO2, Al2O3, and USY. Both V^4+ and V^5+ were preferentially adsorbed on Al2O3 and showed a much smaller pref-erence for USY and SiO2. The observed preference orders are discussed in relation with the properties of the support. In addition, a novel method is proposed to coat the external surface of USY with a thin film of Al2O3. The method is based on the deposition of USY with the so-called Keggin ion, [Al13O4(OH)24(H2O)12]7+ , which is too big to enter the USY channels or pores. The obtained Al2O3/USY material showed a preferential adsorption of V^4+ onto the Al2O3 film, suggesting that this method could be useful for vanadium passivation of FCC catalysts

Comparative Study on Quality Parameters of Royal Jelly, Apilarnil and Queen Bee Larvae Triturate

Given their beneficial effects in terms of health, the natural products, especially beehive products, have drawn the attention of consumers since long time ago. In order to guarantee the quality of these products on the market, their chemical composition needs to be analyzed. Thus, this current research had as objective the establishment of quality parameters for beehive brood food derived products: apilarnil and queen bee larvae triturate. These two products were compared with royal jelly which is the basis of brood food in the first 3 days of larval stage. The carbohydrates were determined by HPLC-IR and allowed the identification of seven carbohydrate compounds, predominantly glucose, fructose and sucrose. The lipid profile was analyzed by the Soxhlet method. The total protein content was determined by the Kjeldahl method. Free amino acids were analyzed by LC-MS. A total of 31 amino acids were identified of which nine are essential amino acids for humans.Â

Spectroscopic characterization of heterogeneous catalysts

Transition metal ions - elements with a partially filled d shell - on surfaces of inorganic oxides possess a wide variability in oxidation state, coordination number and molecular structure. This variability forms the basis for their diverse chemical behavior, which is especially important in the field of heterogeneous catalysis. The characterization of supported transition metal ions is a very demanding job, which requires the use of a battery of advanced preferably in situ spectroscopic techniques

Spectroscopy of Transition Metal Ions on Surfaces

Chemical industries are based on catalytic processes as both bulk and fine chemicals are often produced with heterogeneous catalysts. Transition metal ions dispersed on high-surface area inorganic solids are very important catalysts and a full characterization of these materials requires a profound knowledge of the oxidation state, coordination environment and dispersion of the metal ions on the catalyst surface. Such information can only be obtained by using a combination of complementary spectroscopic techniques. 'Spectroscopy of Transition metal ions on Surfaces' serves as an introduction to some of the most important spectroscopic techniques nowadays used for studying the chemistry and catalytic properties of transition metal ions on surfaces. The basic principles and the strengths and weaknesses of continuous wave electron spin resonance, pulsed electron spin resonance, solid state nuclear magnetic resonance, infrared spectroscopy, Raman spectroscopy, diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy are critically reviewed by internationally recognized experts. This gives the reader a solid background for judging literature results and for planning and conducting his/her own experiments. Each chapter closes with several relevant examples mainly from the recent literature. In addition, the use of in situ techniques and chemometrical techniques has been included because of its growing importance in catalyst characterization. As a consequence, the book has been written as a text not only for graduate students, but also for anyone else who is new in the field and wants a recent update. The following scientists have contributed to this textbook: B

Diagnostic challenge – West Nile encephalitis mimicking stroke – case report

West Nile virus (WNV) is widely distributed around the world. The WNV is maintained in nature by a cycle involving mosquitoes and birds, which are presumed to be the most important amplifying hosts. We present the case of a 75 years old male patient admitted to the neurology department for several symptoms that could be attributed to a stroke. The symptomatology had an acute onset. The computed tomography and the magnetic resonance imaging revealed lacunar stroke in right semioval center. The final diagnosis was established by the lumbar punction: West Nile virus was highlighted in the cerebrospinal fluid,clinical evolution was favorable, the patient was discharge with minimal neurologic deficits

AlOx Coating of Ultrastable Zeolite Y: A Possible Method for Vanadium Passivation of FCC Catalysts

AlOx coating is proposed as a possible method for vanadium passivation of the ultrastable zeolite Y (USY). Two coating methods are discussed: (i) the deposition of the [Al13O4(OH)24(H2O)12]7+ ([Al13]) complex from aqueous solutions and (ii) the anchoring of alumoxane by in situ triisobutylaluminum hydrolysis followed by calcination. The properties and the efficiency in vanadium passivation of the coated materials have been investigated with DRS, ESR, XPS, FTIR, and sorption measurements. XPS revealed for all the coated samples an enrichment in the Al content in the near-surface region and differences in Al coordination geometry. Vanadyl(IV) etioporphyrin, the major contaminant in crude oil, was used to probe the trapping efficiency of the external AlOx layer. The [Al13]-derived layer is homogeneously distributed and covers the external surface of the USY zeolite, following its topology, but without blocking its pores. About 80% of the offered vanadyl species have been preferentially trapped in this layer. The alumoxane-based method is less efficient in vanadium passivation, most probably because after calcination the aluminum species are heterogeneously distributed, both on the external surface and in the channels of USY zeolite

AlOx Coating of Ultrastable Zeolite Y: A Possible Method for Vanadium Passivation of FCC Catalysts

AlOx coating is proposed as a possible method for vanadium passivation of the ultrastable zeolite Y (USY). Two coating methods are discussed: (i) the deposition of the [Al13O4(OH)24(H2O)12]7+ ([Al13]) complex from aqueous solutions and (ii) the anchoring of alumoxane by in situ triisobutylaluminum hydrolysis followed by calcination. The properties and the efficiency in vanadium passivation of the coated materials have been investigated with DRS, ESR, XPS, FTIR, and sorption measurements. XPS revealed for all the coated samples an enrichment in the Al content in the near-surface region and differences in Al coordination geometry. Vanadyl(IV) etioporphyrin, the major contaminant in crude oil, was used to probe the trapping efficiency of the external AlOx layer. The [Al13]-derived layer is homogeneously distributed and covers the external surface of the USY zeolite, following its topology, but without blocking its pores. About 80% of the offered vanadyl species have been preferentially trapped in this layer. The alumoxane-based method is less efficient in vanadium passivation, most probably because after calcination the aluminum species are heterogeneously distributed, both on the external surface and in the channels of USY zeolite