Effect of Atomic Layer Deposition Support Thickness on Structural Properties and Oxidative Dehydrogenation of Propane on Alumina- and Titania-Supported Vanadia

Abstract  

Engineered solid supports for vanadium catalysts were prepared by atomic layer deposition (ALD) of alumina and titania layers on silica. The thickness of these layers was found to have a significant effect on the structure of the solid supports, their interaction with vanadia, and their catalytic performance with regard to oxidative dehydrogenation of propane. The catalytic performance of supported vanadia catalysts is reported for both ALD-engineered and conventional solid supports (γ-Al₂O₃ and TiO₂). The analysis results indicated that the engineered supports behave as a separate phase rather than a cross between the base silica and the deposited alumina or titania.     

Effect of Temperature and Water on the Selective Oxidation of H<Subscript>2</Subscript>S to Elemental Sulfur on a Macroscopic Carbon Nanofiber Based Catalyst

Abstract  

Carbon nanofibers were synthesized on graphite felt substrate by catalytic decomposition of ethane. The preshaped material was efficiently used as catalyst support for the active phase NiS₂ in the direct oxidation of H₂S into elemental sulfur. The catalyst was extremely active, selective, and stable at 60 °C in a fixed bed reactor due to the high resistance of carbon nanofiber based catalyst to the solid sulfur loading. This is explained by the specific mode of sulfur deposition, involving the role of water in the sulfur transport and the hydrophobic nature of the support.     

A Cyclic Catalyst Pretreatment in CO<Subscript>2</Subscript> for High Yield Production of Carbon Nanofibers with Narrow Diameter Distribution

Abstract  

This paper presents a cyclic catalyst pretreatment process to improve the CNF yield with narrow size distribution by sequentially feeding the CVD reactor with CH₄/CO₂ mixtures (carbon deposition) and CO₂ (carbon removal) prior to the actual growth process. A mechanism based on a break-up of large Ni particles tentatively explains the beneficial effect of the cyclic carbon deposition/removal CVD procedure.     

Role of CeO<Subscript>2</Subscript> in Rh/α-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Catalysts for CO<Subscript>2</Subscript> Reforming of Methane

Abstract  

The Rh/α-Al₂O₃ catalyst was modified by CeO₂ in order to improve the thermal stability and the carbon deposition resistance during the CO₂ reforming of methane The carbon formation was determined by TPO, TEM and Raman spectroscopy. Characterization results showed that the incorporation of Ce in the support inhibits the carbon deposition, increasing the useful life and the stability of the Rh base catalysts.     

Selective Allylic oxidation of Cyclohexene by a Magnetically Recoverable Cobalt Oxide Catalyst

Abstract  

In this work, we prepared a new magnetically recoverable CoO catalyst through the deposition of the catalytic active metal nanoparticles of 2–3 nm on silica-coated magnetite nanoparticles to facilitate the solid separation from liquid media. The catalyst was fully characterized and presented interesting properties in the oxidation of cyclohexene, as for example, selectivity to the allylic oxidation product. It was also observed that CoO is the most active species when compared to Co²⁺, Co₃O₄ and Fe₃O₄ in the catalytic conditions studied.     

MnCu Catalyst Deposited on Metallic Monoliths for Total Oxidation of Volatile Organic Compounds

Abstract  

The MnCu mixed catalyst with a Mn:Cu = 9:1 molar ratio prepared by coprecipitation method was deposited by washcoating on a FeCrAlloy monolith (FM-W). On the other hand, an anodized aluminum monolith was impregnated with an aqueous solution of manganese and copper acetates in Mn:Cu = 9:1 molar ratio (AM-2IS). The structured catalysts were evaluated in volatile organic compounds (VOCs) combustion. The effects of the deposition methods used and the nature of the structured supports on the catalytic activity were observed. The FM-W monolithic catalyst and the Mn9Cu1 powder catalyst showed the same catalytic behavior for the combustion of all VOCs tested. The influence of the nature of structured support was not observed. The AM-2IS monolithic catalyst showed a slightly higher catalytic activity in most of the tested molecules, than FM-W catalyst. The effect of the substitution of orbital stirring by recirculation during the impregnation process on the loading of the deposited phase, and its effect on the catalytic activity were observed.     

Development of robust YSZ thin-film electrolyte by RF sputtering and anode support design for stable IT-SOFC

Thin-film solid oxide fuel cells (TF-SOFCs) have attracted attention as a strategy for lowering the operating temperature of SOFCs. However, the porous and rough surface of the SOFC support and the shadowing effect have hindered the construction of pinhole-free thin-film electrolytes during sputtering. In this study, we report the deposition of a gas-tight YSZ thin-film electrolyte (approximately 0.8 μm) by RF sputtering on a Ni-YSZ anode support. To utilize a sputtered thin film as an electrolyte, we examined the relationship between the deposition pressure and thin-film properties and determined the optimal deposition conditions. By designing the anode functional layer (AFL) and annealing, a thin-film electrolyte is successfully deposited on the porous Ni-YSZ support without cracks and pinholes. The resulting thin-film electrolyte cell achieves a high open-circuit voltage (OCV) of approximately 1.09 V and a maximum power density of 0.446 W/cm² at 600 °C, which implies high ionic conductivity and gas tightness. Moreover, the single cell exhibited exceptional long-term stability (140 h) despite the extremely thin and vacuum-deposited electrolyte components. This study provides guidelines for the practical application of thin films as electrolytes to lower the operating temperature of SOFCs.     

Synthesis and Application of Polystyrene Nanospheres Supported Platinum Catalysts in Enantioselective Hydrogenations

Abstract  

Nearly monodisperse polystyrene nanospheres coated with platinum have been synthesized and applied successfully in the cinchona alkaloid-modified enantioselective hydrogenation of ethyl pyruvate. During the catalyst preparation broadly varied experimental conditions were used resulting in several catalysts with different properties. The effect of hydrogen pressure, solvent, modifier and polystyrene nanoparticle size on the enantioselectivity was also studied. Based on the results the effect of support on the mechanism of the enantiodifferentiation has been discussed.     

Variation in Catalytic Activity of Carbon Black during Methane Decomposition: Active Site Estimations from Surface Structural Characteristics

Abstract  

The variation in the catalytic activity of carbon black (CB) during methane decomposition was investigated by considering the number of active sites of CB. We demonstrated that the activity variation could be well estimated by assuming the edge length of graphitic sheets evolving from the CB surface. The results suggested that the activity variation originated from surface structural changes due to carbon deposition.     

Ca-Containing Mesoporous Silica as a Solid Base Catalyst for the Knoevenagel Condensation Reaction

Abstract  

We synthesized Ca-containing FSM-16 (Ca-FSM-16) for use as a solid base catalyst for the Knoevenagel condensation reaction. Extended X-ray absorption fine structure (EXAFS) results indicated that Ca species were introduced as a calcium silicate-like phase with distorted tetrahedral coordination into the pore walls of FSM-16. Compared with conventional aminopropyl-functionalized mesoporous silica, Ca-FSM-16 showed higher activity as a solid-base catalyst for the Knoevenagel condensation reaction.     

Gas-tight yttria-doped barium zirconate thin film electrolyte via chemical solution deposition technique

A 500 nm thick yttria-doped barium zirconate (BZY) proton conducting electrolyte film, fabricated via a low-cost and high-throughput chemical solution deposition (CSD) technique, was sintered at a remarkably low temperature of 1000 °C, which is much lower than the typical solid state sintering temperature of minimum 1300 °C. Therefore, the detrimental issues, commonly encountered in solid state sintering, such as barium evaporation and phase separation, were not observed. Gas-tightness of the BZY film was confirmed by 8 h of stable open circuit voltage (OCV) at 1.08 V from a button fuel cell with NiO-BZY anode substrate and LSCF cathode. The application of the film is aimed at the electrolytes of intermediate to low temperature solid oxide fuel cells (SOFCs).     

Selective Oxidation of Glycerol Catalyzed by Rh/Activated Carbon: Importance of Support Surface Chemistry

Abstract  

Noble metal catalysts (Pt, Ir, Pd, Rh, Au) supported on activated carbon were assessed for glycerol oxidation. Rhodium is a highly efficient catalyst when the support has neutral or basic properties. The surface chemistry of activated carbon plays a key role in the performance.     

Carbon black nanoparticles induce type II epithelial cells to release chemotaxins for alveolar macrophages

Background  

Alveolar macrophages are a key cell in dealing with particles deposited in the lungs and in determining the subsequent response to that particle exposure. Nanoparticles are considered a potential threat to the lungs and the mechanism of pulmonary response to nanoparticles is currently under intense scrutiny. The type II alveolar epithelial cell has previously been shown to release chemoattractants which can recruit alveolar macrophages to sites of particle deposition. The aim of this study was to assess the responses of a type II epithelial cell line (L-2) to both fine and nanoparticle exposure in terms of secretion of chemotactic substances capable of inducing macrophage migration.     

Single-Walled Carbon Nanotube (SWCNT)-induced interstitial fibrosis in the lungs of rats is associated with increased levels of PDGF mRNA and the formation of unique intercellular carbon structures that bridge alveolar macrophages In Situ

Background  

Nanotechnology is a rapidly advancing industry with many new products already available to the public. Therefore, it is essential to gain an understanding of the possible health risks associated with exposure to nanomaterials and to identify biomarkers of exposure. In this study, we investigated the fibrogenic potential of SWCNT synthesized by chemical vapor deposition using cobalt (Co) and molybdenum (Mo) as catalysts. Following a single oropharyngeal aspiration of SWCNT in rats, we evaluated lung histopathology, cell proliferation, and growth factor mRNAs at 1 and 21 days post-exposure. Comparisons were made to vehicle alone (saline containing a biocompatible nonionic surfactant), inert carbon black (CB) nanoparticles, or vanadium pentoxide (V₂O₅) as a known inducer of fibrosis.     

Mono and Bifunctional Catalysts for Styrene Oxide Isomerization or Hydrogenation

Abstract  

Styrene oxide can be effectively isomerized to phenyl-acetaldehyde (98%) over amorphous silica alumina catalysts under very mild liquid phase conditions. On the other hand, a copper catalyst prepared using a silica zirconia support gave up to 80% yield in the hydrogenation of styrene oxide to 2-phenyl-ethanol.     

Experimental determination of the respiratory tract deposition of diesel combustion particles in patients with chronic obstructive pulmonary disease

Background

Air pollution, mainly from combustion, is one of the leading global health risk factors. A susceptible group is the more than 200 million people worldwide suffering from chronic obstructive pulmonary disease (COPD). There are few data on lung deposition of airborne particles in patients with COPD and none for combustion particles.

Objectives

To determine respiratory tract deposition of diesel combustion particles in patients with COPD during spontaneous breathing.

Methods

Ten COPD patients and seven healthy subjects inhaled diesel exhaust particles generated during idling and transient driving in an exposure chamber. The respiratory tract deposition of the particles was measured in the size range 10?C500?nm during spontaneous breathing.

Results

The deposited dose rate increased with increasing severity of the disease. However, the deposition probability of the ultrafine combustion particles (< 100?nm) was decreased in COPD patients. The deposition probability was associated with both breathing parameters and lung function, but could be predicted only based on lung function.

Conclusions

The higher deposited dose rate of inhaled air pollution particles in COPD patients may be one of the factors contributing to their increased vulnerability. The strong correlations between lung function and particle deposition, especially in the size range of 20?C30?nm, suggest that altered particle deposition could be used as an indicator respiratory disease.     

Electrochemical behavior of AZ91D magnesium alloy in phosphate medium: Part II. Induced passivation

Induced passivation of AZ91D magnesium alloy in phosphate solution was carried out both chemically, using various inorganic oxidants, namely, molybdate, vanadate and iodate, as well as electrochemically by anodizing the alloy under various controlled overpotentials within the range 0.1–3.4 V. In acidic phosphate (pH 4.5), molybdate and vanadate anions exhibit similar behavior, as they show a dissolution effect at lower concentrations and passivation at higher concentrations. On the other hand, iodate anions shows critical behavior with a passivation effect up to 0.1 mM and depassivation for higher concentrations. Generally, over the concentration domain (0.01–1.0 mM) the results reveal small inhibitive effects with maximum values of 19.7% for and 24–25% for and manifesting weak propensities for these inorganic species to enhance the corrosion resistance of AZ91D alloy in acidic phosphate medium. The effect of anodic potential on the characteristics of surface films formed on the alloy in alkaline phosphate solution (pH 11.9) indicates that higher forming overpotential induces better passivation due to the formation of rather thicker and more resistive anodic films. The stability of the films is greater in alkaline as compared to acidic phosphate solutions.     

High cocoa polyphenol rich chocolate may reduce the burden of the symptoms in chronic fatigue syndrome

Background  

Chocolate is rich in flavonoids that have been shown to be of benefit in disparate conditions including cardiovascular disease and cancer. The effect of polyphenol rich chocolate in subjects with chronic fatigue syndrome (CFS) has not been studied previously.     

In-doped LiCa2.98MgV3O12 rare-earth-free phosphor with a high photoluminescence quantum yield of 67.4%

Rare earth resources applied in numerous novel materials, are increasingly scarce in worldwide. Meanwhile, great attention has been focused on the blue rare-earth-free fluorescent phosphors as an excitation source of near-ultraviolet (NUV) chips, which are available in white-light-emitting diodes (WLEDs) that combined with yellow commercial phosphors. Many solutions have been found to improve the photoluminescence quantum yield (PLQY) of phosphor. In this study, we effectively increased PLQY by introducing indium ion to vanadate garnet phosphor forming a series of LiCa_3−XMgV₃O₁₂: xIn³⁺ (x = 0.01, 0.02, 0.04, 0.06, 0.08, and 0.10). The resultant In-doped vanadate garnet phosphors exhibit a relative increase in PLQY, and the optimal phosphors is LiCa_2.98MgV₃O₁₂: 0.02In³⁺ with a PLQY as high as 67.4%. These In-doped vanadate garnet phosphors have a broad emission at 480 under 320 nm where near UV-light excitation. It is revealed that the distortion of V-V and V-O bond length in [VO₄] crystal structure and unit cell volume data of phosphors have an extensive influence on PLQY. Therefore, these novel vanadate garnet phosphors can be the essential blue color choice for WLED devices application in illumination.     

Synthesis of Sulfonated Carbon Nanocage and Its Performance as Solid Acid Catalyst

Abstract  

A carbon nanocage material (CKT) was first successfully sulfonated by introducing sulfophenyl groups on the surface of pore channels through benzenesulfonic acid-containing aryl radical in situ generated from the reaction of 4-aminobenzenesulfonic acid and isoamyl nitrite in water. The sulfonated carbon nanocage material (S-CKT) was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, powder small-angle X-ray diffraction and nitrogen sorption measurements. The results showed that the S-CKT still possess the high specific surface area (787 m²/g) and uniform mesoporous (pore diameter 4.7 nm) structures, although the structure of S-CKT is slightly disorder, compared with its unsulfonated precursor. S-CKT, as a carbon-based solid acid catalyst, showed good catalytic performance and reusability in the cross-Aldol condensation of ketones with aromatic aldehydes under solvent-free condition.