The characterization and chemical reactivity of powdered wool

Wool powders with various particle sizes have been produced using different milling techniques. Scanning electron microscopy (SEM) showed gradual breakdown of the fibre as it was progressively converted into powder form. Chlorination enhanced the effectiveness of subsequent air-jet milling. X-ray photoelectron spectroscopy (XPS) revealed an increase in the surface concentrations of oxygen and nitrogen, and a decrease in carbon and sulphur on conversion of the fibres into powders, as the cortex became exposed on the powder surface. An increased surface concentration of cysteic acid was observed for the chlorinated powder. Rapid uptake of dye by wool powders was observed in situations where there was virtually no uptake by the original fibre. Hydrophobic dyes were more readily sorbed than were hydrophilic dyes. The chlorination treatment led to a decrease in the sorption of acid dyes. Confocal microscopy, used in conjunction with a fluorescent stain, showed that chemicals were able to penetrate wool particles, even at room temperature. The rate and extent of uptake of dye by the finer powders were comparable to that obtained with activated charcoal, even though the surface area of the charcoal was 100 times greater.     

Phenyl methacrylate-glycidyl methacrylate copolymers: synthesis, characterization and reactivity ratios by spectroscopic methods

The free-radical polymerization of phenyl methacrylate and glycidyl methacrylate was carried out at 70°C in the presence of benzoyl peroxide using 2-butanone as the solvent. The copolymer compositions of seven copolymer samples with different feed compositions as well as the tacticities were determined by ¹H nuclear magnetic resonance spectroscopy. The results were used to calculate the reactivity ratios by the Kelen-Tudos method, which were found to be r₁ = 1.57 ± 0.56 and r₂ = 0.84 ± 0.51. The homo- and copolymers were also characterized by Fourier-transform infra-red and ¹³C nuclear magnetic resonance spectroscopic methods. , and polydispersity indices of the copolymers were determined using gel permeation chromatography.     

Synthesis,characterization and compared reactivity of asymmetrical ansa-metallocenes

Rac and meso ansa-zirconocenes [Zr{1-Me₂Si(3-R-(η⁵-C₉H₅))(3-R′-(η⁵-C₉H₅))}Cl₂] (R = Et, R′ = H; R = Pr, R′ = H; and R = Et, R′ = Pr) 4–9 have been prepared by the reaction of ZrCl₄ with the corresponding dilithiated derivatives from the ligands {1-Me₂Si(3-R-(η⁵-C₉H₅))(3-R′-(η⁵-C₉H₅))} (R = Et, R′ = H 1; R = Pr, R′ = H 2; and R = Et, R′ = Pr 3) in diethyl ether/toluene at ?78 °C. The molecular structure of rac [Zr{1-Me₂Si(3-Et-(η⁵-C₉H₅))(3-Pr-(η⁵-C₉H₅))}Cl₂] 8 has been determined by single crystal X-ray diffraction studies, which show a pseudotetrahedral environment formed by the two chlorine ligands and two η⁵-coordinated indenyl ligands. The activity in homogeneous and heterogeneous polymerization is compared and discussed.     

Structural characterization and chemical reactivity of dual doped graphene

Herein, we employed first-principle calculations to study the structure and reactivity of dual-doped graphene. The new materials were derived from graphene by replacing two carbon atoms with one 2p element (B, N or O), and one 3p element (Al, Si, P or S). A total of 12 dual-doped graphenes were used to perform a comparative study and identify the most promising materials for the development of new catalysts and anchoring nanoparticles. The structural analysis indicated that in all cases, except SiB, the dopants prefer to replace a CC bond. Yet, not always the dopants are bonded, presenting an edge-like bonding. As regards chemical reactivity, in general the introduction of two atoms remarkably increases reactivity as compared to graphene. The most prominent examples are Al–O, S–N, P–O and Si–B(para) codoped graphene which present reactivity higher than perfect and monodoped graphenes. This effect was attributed to the strong charge redistribution induced by the dopants. In most cases the heteroatoms are the most reactive sites, but in others the carbon atoms are more reactive, as in Al–O and Si–B codoped graphene. The combination of 2p and 3p dopants offers the possibility of adjusting over a wide range the reactivity of graphene.     

自动电位滴定法测定甲苯二异氰酸酯总酸度

利用氢氧化钾-甲醇溶液作标准溶液，非水中和滴定法，快速测定甲苯二异氰酸酯总酸度。     

Acidity Characterization of Catalyst Libraries by High-Throughput Testing

The development of acid and bi-functional catalysts with controlled properties is a matter of high interest for refinery applications. The issues of characterization and quantification of catalyst acidity in the frame of high throughput (HT) screening are outlined. The present study deals with the development of a HT method for the characterization of the Brønsted acidity of 80 bifunctional catalysts library by means of isomerization of 3,3-dimethylbutene testing. Catalytic results are validated with literature data. The choice of probe molecules, the operating conditions and deactivation issues upon testing are addressed. This method allows quantifying very accurately the acid strength. Catalyst ranking from large library can be achieved an acidity scale in conditions similar to the practical applications. The pros and cons of the use of model reactions for HT quantitative characterization are discussed.     

Platinum(VI) dihydroxo tetramesitylporphyrin; characterization and chemical reactivity

Tetramesitylporphyrin platinum(VI) dihydroxo complex, TMPPt(OH)₂ · 2 benzoate was synthesized by addition of two equivalent of meta-chloroperbenzoic acid molecules to the tetramesitylporphyrin platinum(II). This complex was characterized by X-ray diffraction and spectroscopic methods, and is capable to convert two molecules of triphenylphosphine to triphenylphosphine oxide.     

Determination of heats of adsorption on activated carbons by flow microcalorimetry

Heats of adsorption of different adsorbates on base and impregnated carbons were measured with a flow microcalorimeter using a pulse injection technique. Water, methanol, freon 22, n-hexane and n-heptane were utilized as adsorbates. BPL carbon, ASC carbon and TEDA-ASC carbon were used as adsorbents. The heats of adsorption of each adsorbate were measured on each carbon at two different relative humidities (0 and 70%) to determine the effect of moisture. Methanol adsorbed on silica gel was chosen as a reference system to establish the accuracy and reproducibility of the technique.     

Synthesis, characterization and photocatalytic reactivity of Ti-containing micro- and mesoporous materials

Ti-oxides incorporated within the framework of microporous zeolites and mesoporous molecular sieves were found to exhibit high and unique photocatalytic activity for the decomposition of NO into N₂ and O₂ as well as the reduction of CO₂ with H₂O to produce CH₄ and CH₃OH. Spectroscopic investigations of these catalytic systems using photoluminescence, UV-vis, XAFS (XANES and FT-EXAFS) and IR analyses revealed that the charge transfer excited state of the isolated tetra-coordinated Ti-oxides plays a vital role in these photocatalytic reactions. The reactivity of such Ti-oxides was found to depend strongly on their local structures which were controlled by the unique framework structures of the micro- and mesoporous material supports.     

Characterization of acidic property of sulfo-group functionalized microporous and mesoporous silica by adsorption microcalorimetry

Sulfo-group functionalized microporous and mesoporous silica based-on a MCM-41 framework which showed solid acid property were synthesized and characterized by adsorption microcalorimetry. Both the sulfo-functionalized microporous and mesoporous silica (Micro-SO₃H and Meso-SO₃H) were prepared by the oxidation of thiol group (–SH) included mesoporous silica which was obtained through the hydrolysis and co-condensation of tetramethoxysilane (TMOS) and mercaptopropyl trimethoxysilane (MPTMS). The samples have an ordered two-dimensional hexagonal pore array similar to that of MCM-41 as depicted from the XRD patterns. Nitrogen adsorption also shows that both microporous and mesoporous silica have pore characteristics similar to MCM-41, i.e. high surface area and high pore volume. However, pore regularity, surface area and pore volume decreased as the MPTMS loading increased. Solid-state ²⁹Si NMR indicated that the sulfo groups were successfully incorporated into both microporous and mesoporous silica frameworks. This sulfo-functionalized porous silica have high NH₃ uptakes and high differential heats of NH₃ adsorption, suggesting the presence of strong acidic sulfo groups on the silica surface. Acid catalyses of the samples were characterized by the isomerization reaction of but-1-ene to cis, trans-but-2-ene.     

Synthesis, characterization and photocatalytic reactivity of Ti-containing micro- and mesoporous materials

Ti-oxides incorporated within the framework of microporous zeolites and mesoporous molecular sieves were found to exhibit high and unique photocatalytic activity for the decomposition of NO into N₂ and O₂ as well as the reduction of CO₂ with H₂O to produce CH₄ and CH₃OH. Spectroscopic investigations of these catalytic systems using photoluminescence, UV-vis, XAFS (XANES and FT-EXAFS) and IR analyses revealed that the charge transfer excited state of the isolated tetra-coordinated Ti-oxides plays a vital role in these photocatalytic reactions. The reactivity of such Ti-oxides was found to depend strongly on their local structures which were controlled by the unique framework structures of the micro- and mesoporous material supports.     

The relationship between chemical structure and reactivity of alberta bitumens and heavy oils

Long residues (424°C +) from Athabasca, Cold Lake, Lloydminster, and Peace River were hydrocracked over a commercial NilMo on y-alumina catalyst at 430°C, 13.9 MPa (2000 psia). The conversion of residue fraction ranged from 55 to 68%, and was correlated with the concentration of carbon bound to aromatic rings in the feeds. Conversions of sulfur, Micro-Carbon Residue, and metals were all highest for Peace River feed, following the same ranking as residue conversion. Estimates for the breakage of carbon-carbon bonds and the uptake of hydrogen were diagnostic in interpreting the reactor performance.     

三塔精馏精甲醇的酸度控制

分析了三塔精馏过程中精甲醇酸值高的原因,提出了精甲醇酸度的控制方法:预精馏塔pH值的控制、预精馏塔不凝气温度的控制、甲醇合成反应的控制、常压塔侧线采出量的控制以及控制加压塔和常压塔的操作等,通过优化控制,精甲醇优等品率可达到90%以上。     

Individual Particle Morphology and Acidity

The morphological characterization of particles during the Pittsburgh Air Quality Study (PAQS) suggests that particle shape and physical state depends on their acidity. The aerosol shape parameters measured by Computer-Controlled Scanning Electron Microscopy (CCSEM) are statistically different in periods when atmospheric particles are neutral and when they are acidic. High concentrations of particles smaller than 500 nm with high sulfur content and liquid appearance or signs of a previous liquid state before partial or total recrystallization are present on filters collected in days with high aerosol acidity. By contrast, in winter and summer periods in which the aerosol was neutral, the shape parameter values are similar and suggest that the particles have been dried out. These direct observations support the hypothesis that during summer acidic periods in the Eastern United States the particles may contain some water even at low relative humidity both in the atmosphere and on filters.     

A preliminary investigation of PAN based carbon fibre surfaces by flow microcalorimetry

The adsorption of n-butylamine, n-butyric acid, n-butanol and 1.2 epoxy propane from n-heptane solutions onto carbon fibres (PAN) has been investigated by flow microcalorimetry. No adsorption of n-butyric acid could be detected, but the adsorption of n-butanol and 1.2 epoxy propane was reversible and relatively unaffected by surface treatments. In contrast, the adsorption of n-butylamine was very strong, partially irreversible in character and was increased markedly by surface treatment. The areas of the exothermic peaks of irreversibly and reversibly adsorbed n-butylamine were measured, and the former is considered to be a semi-quantitative estimate of the surface acidity. The surface acidity, estimated in this way, is increased by the manufacturer's surface treatment, but the external area of the fibres is relatively unchanged suggesting an increase in the fraction of acid groups at the surface. HM fibres oxidised in nitric acid show an increase in both peak areas and in the external area. When the peak areas are related to the active surface areas of the fibres, however, it is clear that the fraction of the active, or edge, surface occupied by acid groups is greater on fibres oxidised in nitric acid than on those surface treated by the supplier.     

磷化镍的制备、表征及其催化性能研究进展

原油的劣质化和环保法规的日益严格使馏分油的加氢精制技术面临严峻挑战,近年来,磷化镍（Ni2P）由于具有优异的加氢脱硫和加氢脱氮性能已成为新型催化加氢材料研究的焦点。本文综述了Ni2P的制备、表征和催化性能方面的研究进展。磷化氢还原法、次磷酸盐还原法和氢气等离子体还原法可在较低温度下制备高活性Ni2P催化剂。扫描透射电镜表明Ni2P（0001）表面有Ni3P和Ni3P2两种可能的终端结构。Ni3P终端的Ni是四方锥型结构,有解离H吸附;而Ni3P2终端的Ni是四面体型结构,无解离H吸附,这表明四方锥型的Ni活性点具有高反应活性。从目前的研究看,Ni2P是具有潜在应用前景的一种新型加氢精制催化材料。     

Electrochemical characterization and reactivity of Pt nanoparticles supported on single-walled carbon nanotubes

Carbon nanotubes have been proposed as advanced metal catalyst support for electrocatalysis. In this paper, Pt nanoparticles supported on single-walled carbon nanotubes (SWCNTs)-Pt, were prepared using a solid-state reaction between the SWCNTs and two different Pt precursors, bis(dibenzylideneacetone)platinum [Pt(DBA)₂] or tri(dibenzylideneacetone)platinum [Pt(DBA)₃]. TEM images of the samples show Pt nanoparticles with a particle size around 2.5 nm with a high degree of dispersion on the SWCNTs. A detailed electrochemical characterization of the surface of the samples including irreversibly adsorbed adatoms of Bi and Ge as probe reactions has been carried out. It has been stated that SWCNTs-Pt samples subjected to the classical electrochemical activation induce a serious sintering of the Pt nanoparticles.